Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
KA FAI WILLIAM TSE Last modified date:2021.10.25

Associate Professor / Attached Promotive Center for International Education and Research of Agriculture / Faculty of Agriculture

1. Zhu, P.; Wong, M. K. -S; Lin, X.; Chan, T. F.; Wong, C. K. C.; Lai, K. P.; Tse, W. K. F., Changes of the intestinal microbiota along the gut of Japanese Eel (Anguilla japonica), LETTERS IN APPLIED MICROBIOLOGY, 10.1111/lam.13539, 73, 4, 529-541, 2021.10.
2. Lai, Keng Po; Tam, Nathan; Wang, Simon Yuan; Tse, William Ka Fai; Lin, Xiao; Chan, Ting Fung; Tong, Yin; Zhang, Jianwen; Au, Doris Wai Ting; Sun, Rudolf Shiu; Kong, Richard Yuen Chong, Proteomic Response of the Brain to Hypoxic Stress in Marine Medaka Fish (Oryzias melastigma), FRONTIERS IN MARINE SCIENCE, 10.3389/fmars.2021.618489, 8, 2021.05.
3. Lai, Keng Po; Gong, Zhiyuan; Tse, William Ka Fai, Zebrafish as the toxicant screening model: Transgenic and omics approaches, AQUATIC TOXICOLOGY, 10.1016/j.aquatox.2021.105813, 234, 2021.05.
4. Lo, Hoi Shing; Po, Beverly Hoi Ki; Li, Laam; Wong, Aman Yi Man; Kong, Richard Yuen Chong; Li, Lei; Tse, William Ka Fai; Wong, Chris Kong Chu; Cheung, Siu Gin; Lai, Keng Po, Bisphenol A and its analogues in sedimentary microplastics of Hong Kong, MARINE POLLUTION BULLETIN, 10.1016/j.marpolbul.2021.112090, 164, 2021.03.
5. Li, Rong; Huang, Chen; Ho, Jeff Cheuk Hin; Leung, Cherry Chi Tim; Kong, Richard Yuen Chong; Li, Yu; Liang, Xiao; Lai, Keng Po; Tse, William Ka Fai, The use of glutathione to reduce oxidative stress status and its potential for modifying the extracellular matrix organization in cleft lip, FREE RADICAL BIOLOGY AND MEDICINE, 10.1016/j.freeradbiomed.2020.12.455, 164, 130-138, 2021.02, OBJECTIVE:
Cleft lip (CL) is a common congenital anomaly that can be syndromic or non-syndromic. It can be triggered by the mutation of gene or environmental factors. The incidence of CL is about 1 out of 700 live births. Facial development is a complex process, and there is no existing therapy to prevent the disease development. One of the characteristics in this facial malformation is the increased presence of reactive oxygen species (ROS). In this study, we hypothesize that the antioxidant glutathione (GSH) could help to attenuate the oxidative stress in this disease.
Bioinformatics network pharmacology was applied to determine pharmacological targets and molecular mechanisms of GSH treatment for CL. Moreover, RNA-sequencing of the POLR1C knockdown osteoblast CL model was applied to validate the in silico data of using GSH in CL.
Twenty-two core targets of GSH and CL were identified via various bioinformatics tools. The GO and KEGG analysis indicated that GSH could modulate two major families (matrix metalloproteinase and integrins), which are related to extracellular matrix modification and composition for facial development in CL. The findings from POLR1C knockdown model further supported the rescue response of GSH in CL.
The study uncovered the possible pharmacological mechanism of GSH for treating CL. The data helps research group to focus on the specific pathways for understanding the biological action of GSH for treating the CL in the future..
6. Lai, Keng Po; Lin, Xiao; Tam, Nathan; Ho, Jeff Cheuk Hin; Wong, Marty Kwok-Shing; Gu, Jie; Chan, Ting Fung; Tse, William Ka Fai, Osmotic stress induces gut microbiota community shift in fish, ENVIRONMENTAL MICROBIOLOGY, 10.1111/1462-2920.15150, 22, 9, 3784-3802, 2020.09, Alteration of the gut microbiota plays an important role in animal health and metabolic diseases. However, little is known with respect to the influence of environmental osmolality on the gut microbial community. The aim of the current study was to determine whether the reduction in salinity affects the gut microbiota and identify its potential role in salinity acclimation. Using Oryzias melastigma as a model organism to perform progressive hypotonic transfer experiments, we evaluated three conditions: seawater control (SW), SW to 50% sea water transfer (SFW) and SW to SFW to freshwater transfer (FW). Our results showed that the SFW and FW transfer groups contained higher operational taxonomic unit microbiota diversities. The dominant bacteria in all conditions constituted the phylum Proteobacteria, with the majority in the SW and SFW transfer gut comprising Vibrio at the genus level, whereas this population was replaced by Pseudomonas in the FW transfer gut. Furthermore, our data revealed that the FW transfer gut microbiota exhibited a reduced renin–angiotensin system, which is important in SW acclimation. In addition, induced detoxification and immune mechanisms were found in the FW transfer gut microbiota. The shift of the bacteria community in different osmolality environments indicated possible roles of bacteria in facilitating host acclimation..
7. Li, Rong; Wu, Ka; Li, Yu; Liang, Xiao; Tse, William Ka Fai; Yang, Lu; Lai, Keng Po, Revealing the targets and mechanisms of vitamin A in the treatment of COVID-19, AGING-US, 12, 15, 15784-15796, 2020.08.
8. Dahlem, Charlotte; Siow, Wei Xiong; Lopatniuk, Maria; Tse, William K. F.; Kessler, Sonja M.; Kirsch, Susanne H.; Hoppstaedter, Jessica; Vollmar, Angelika M.; Mueller, Rolf; Luzhetskyy, Andriy; Bartel, Karin; Kiemer, Alexandra K, Thioholgamide A, a New Anti-Proliferative Anti-Tumor Agent, Modulates Macrophage Polarization and Metabolism, CANCERS, 10.3390/cancers12051288, 12, 5, 2020.05.
9. Keng Po Lai, Jian Chen, William Ka Fai Tse, Role of deubiquitinases in human cancers
Potential targeted therapy, International journal of molecular sciences, 10.3390/ijms21072548, 21, 7, 2020.04, Deubiquitinases (DUBs) are involved in various cellular functions. They deconjugate ubiquitin (UBQ) from ubiquitylated substrates to regulate their activity and stability. Studies on the roles of deubiquitylation have been conducted in various cancers to identify the carcinogenic roles of DUBs. In this review, we evaluate the biological roles of DUBs in cancer, including proliferation, cell cycle control, apoptosis, the DNA damage response, tumor suppression, oncogenesis, and metastasis. This review mainly focuses on the regulation of different downstream effectors and pathways via biochemical regulation and posttranslational modifications. We summarize the relationship between DUBs and human cancers and discuss the potential of DUBs as therapeutic targets for cancer treatment. This review also provides basic knowledge of DUBs in the development of cancers and highlights the importance of DUBs in cancer biology..
10. Jessica Hoppstädter, Jenny Vanessa Valbuena Perez, Rebecca Linnenberger, Charlotte Dahlem, Thierry M. Legroux, Anne Hecksteden, William K.F. Tse, Sara Flamini, Anastasia Andreas, Jennifer Herrmann, Christian Herr, Rolf Müller, Tim Meyer, Robert Bals, Carlo Riccardi, Stefano Bruscoli, Alexandra K. Kiemer, The glucocorticoid-induced leucine zipper mediates statin-induced muscle damage, FASEB Journal, 10.1096/fj.201902557RRR, 2020.01, Statins, the most prescribed class of drugs for the treatment of hypercholesterolemia, can cause muscle-related adverse effects. It has been shown that the glucocorticoid-induced leucine zipper (GILZ) plays a key role in the anti-myogenic action of dexamethasone. In the present study, we aimed to evaluate the role of GILZ in statin-induced myopathy. Statins induced GILZ expression in C2C12 cells, primary murine myoblasts/myotubes, primary human myoblasts, and in vivo in zebrafish embryos and human quadriceps femoris muscle. Gilz induction was mediated by FOXO3 activation and binding to the Gilz promoter, and could be reversed by the addition of geranylgeranyl, but not farnesyl, pyrophosphate. Atorvastatin decreased Akt phosphorylation and increased cleaved caspase-3 levels in myoblasts. This effect was reversed in myoblasts from GILZ knockout mice. Similarly, myofibers isolated from knockout animals were more resistant toward statin-induced cell death than their wild-type counterparts. Statins also impaired myoblast differentiation, and this effect was accompanied by GILZ induction. The in vivo relevance of our findings was supported by the observation that gilz overexpression in zebrafish embryos led to impaired embryonic muscle development. Taken together, our data point toward GILZ as an essential mediator of the molecular mechanisms leading to statin-induced muscle damage..
11. Rong Li, Chao Guo, Ka Fai William Tse, Min Su, Xiaoxi Zhang, Keng Po Lai, Metabolomic analysis reveals metabolic alterations of human peripheral blood lymphocytes by perfluorooctanoic acid, Chemosphere, 10.1016/j.chemosphere.2019.124810, 239, 2020.01, Perfluorooctanoic acid (PFOA) is a dispersive persistent organic pollutant in the environment. Accumulating reports suggest that PFOA is toxic to human lymphocytes; however, the toxicological effects of PFOA on these cells remain largely unclear. In this study, ultra-performance liquid chromatography (UPLC)-based metabolomic analysis was employed to identify metabolites in human peripheral blood lymphocytes and to assess the metabolic alterations caused by PFOA exposure. Our comparative metabolomic analysis results demonstrated that PFOA treatment could increase the level of organic acids and reduce the level of lipid molecules. Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation further highlighted the fact that the PFOA treatment interfered with the metabolism of amino acids, carbohydrates and lipids, which may lead to disruption of the immune system..
12. Perez, J. V. Valbuena; Hoppstaedter, J.; Tse, W. K. F.; Bruscoli, S.; Flamini, S.; Andreas, A.; Herrmann, J.; Mueller, R.; Riccardi, C.; Kiemer, A. K., The Glucocorticoid-Induced Leucine Zipper (GILZ) mediates statin-induced muscle damage, NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY, 392, S7-S8, 2019.02.
13. Ernest Man Lok Kwong, Jeff Cheuk Hin Ho, Marco Chi Chung Lau, May Su You, Yun Jin Jiang, Ka Fai William Tse, Restoration of polr1c in Early Embryogenesis Rescues the Type 3 Treacher Collins Syndrome Facial Malformation Phenotype in Zebrafish, American Journal of Pathology, 10.1016/j.ajpath.2017.10.004, 188, 2, 336-342, 2018.02, Treacher Collins syndrome (TCS) is a rare congenital birth disorder (1 in 50,000 live births) characterized by severe craniofacial defects. Recently, the authors' group unfolded the pathogenesis of polr1c Type 3 TCS by using the zebrafish model. Facial development depends on the neural crest cells, in which polr1c plays a role in regulating their expression. In this study, the authors aimed to identify the functional time window of polr1c in TCS by the use of photo-morpholino to restore the polr1c expression at different time points. Results suggested that the restoration of polr1c at 8 hours after fertilization could rescue the TCS facial malformation phenotype by correcting the neural crest cell expression, reducing the cell death, and normalizing the p53 mRNA expression level in the rescued morphants. However, such recovery could not be reproduced if the polr1c is restored after 30 hours after fertilization..
14. Keng Po Lai, Jing Woei Li, Chia Hao Hsu, May Su You, Ting Fung Chan, Ka Fai William Tse, Yun Jin Jiang, Comparative transcriptomic characterization of a new mib mutant allele, mibnn2002, in zebrafish, Gene, 10.1016/j.gene.2017.11.016, 642, 51-57, 2018.02, mibnn2002, identified from an allele screen, shows early segmentation defect and severe cell death phenotypes, which are different from those of other described mib mutant alleles. We have previously reported its defects in somitogenesis and identified its origin of mutation, a large deletion in LG2. The report here is a continuous study, where we applied the bioinformatics analysis to profile the genetic background of mibnn2002 mutants. By comparing the transcriptomic data of mibnn2002 mutants with those of AB wild-type, a total of 1945 differentially expressed genes were identified, including 685 up- and 1260 down-regulated genes. The Database for Annotation, Visualization and Integrated Discovery (DAVID) analysis and Ingenuity Pathway Analysis (IPA) identified the enriched pathways and their related biological functions. Our data further demonstrated that the defects in the somitogenesis were related to the down-regulated segmentation genes, such as foxc1a, smyhc1, myod1 and mylpfa..
15. Jie Gu, Shuya Dai, Haitao Liu, Quanquan Cao, Shaowu Yin, Keng Po Lai, Ka Fai William Tse, Chris Kong Chu Wong, Haifeng Shi, Identification of immune-related genes in gill cells of Japanese eels (Anguilla japonica) in adaptation to water salinity changes, Fish and Shellfish Immunology, 10.1016/j.fsi.2017.12.026, 73, 288-296, 2018.02, The changes in ambient salinity influence ion and water homeostasis, hormones secretion, and immune response in fish gills. The physiological functions of hormones and ion transporters in the regulation of gill-osmoregulation have been widely studied, however the modulation of immune response under salinity changes is not determined. Using transcriptome sequencing, we obtained a comprehensive profile of osmo-responsive genes in gill cells of Japanese eel (Anguilla japonica). Herein, we applied bioinformatics analysis to identify the immune-related genes that were significantly higher expressed in gill pavement cells (PVCs) and mitochondrial-rich cells (MRCs) in freshwater (FW) than seawater (SW) adapted fish. We validated the data using the real-time qPCR, which showed a high correlation between the RNA-seq and real-time qPCR data. In addition, the immunohistochemistry results confirmed the changes of the expression of selected immune-related genes, including C-reactive protein (CRP) in PVCs, toll-like receptor 2 (TLR2) in MRCs and interleukin-1 receptor type 2 (IL-1R2) in both PVCs and MRCs. Collectively our results demonstrated that those immune-related genes respond to salinity changes, and might trigger related special signaling pathways and network. This study provides new insights into the impacts of ambient salinity changes on adaptive immune response in fish gill cells..
16. Jie Gu, Shuya Dai, Yanmin Liu, Haitao Liu, Yao Zhang, Xingqi Ji, Feng Yu, Yang Zhou, Liang Chen, Ka Fai William Tse, Chris Kong Chu Wong, Binghai Chen, Haifeng Shi, Activation of Ca2+-sensing receptor as a protective pathway to reduce Cadmium-induced cytotoxicity in renal proximal tubular cells, Scientific Reports, 10.1038/s41598-018-19327-9, 8, 1, 2017.12, Cadmium (Cd), as an extremely toxic metal could accumulate in kidney and induce renal injury. Previous studies have proved that Cd impact on renal cell proliferation, autophagy and apoptosis, but the detoxification drugs and the functional mechanism are still in study. In this study, we used mouse renal tubular epithelial cells (mRTECs) to clarify Cd-induced toxicity and signaling pathways. Moreover, we proposed to elucidate the prevent effect of activation of Ca2+ sensing receptor (CaSR) by Calcimimetic (R-467) on Cd-induced cytotoxicity and underlying mechanisms. Cd induced intracellular Ca2+ elevation through phospholipase C-inositol 1, 4, 5-trisphosphate (PLC) followed stimulating p38 mitogen-activated protein kinases (MAPK) activation and suppressing extracellular signal-regulated kinase (ERK) activation, which leaded to increase apoptotic cell death and inhibit cell proliferation. Cd induced p38 activation also contribute to autophagic flux inhibition that aggravated Cd induced apoptosis. R-467 reinstated Cd-induced elevation of intracellular Ca2+ and apoptosis, and it also increased cell proliferation and restored autophagic flux by switching p38 to ERK pathway. The identification of the activation of CaSR-mediated protective pathway in renal cells sheds light on a possible cellular protective mechanism against Cd-induced kidney injury..
17. Keng Po Lai, Angela Hoi Yan Cheung, Ka Fai William Tse, Deubiquitinase Usp18 prevents cellular apoptosis from oxidative stress in liver cells, Cell Biology International, 10.1002/cbin.10799, 41, 8, 914-921, 2017.08, Deubiquitinases (DUBs) deconjugate ubiquitin (UBQ) from ubiquitylated substrates to regulate their activity and stability. They play different cellular functions such as cell cycle regulation, DNA repair, and early embryogenesis. Additionally, studies have demonstrated that some DUBs are the signaling targets of cellular stress such as oxidative stress. Reactive oxygen species are generated during normal mitochondrial oxidative metabolism and proper cellular mechanism could protect the cell from the oxidative stress. However, there are limited studies that specifically focus on the role of DUBs in oxidative stress, and thus the underlying protective mechanism by DUBs is not yet known. The report here, for the first time, applied the mouse-specific DUB RT2 Profiler PCR array to identify DUBs that are responsive to oxidative stress. Out of the tested 83 DUBs, 15 of them were found to be differentially expressed. Among them, Usp18 was found to be induced with a dose- and time-dependent manner of oxidative stress. In functional studies, depletion of Usp18 could stimulate the p53 and caspase 3 protein levels. In addition, knockdown of Usp18 could lead to the reduced cell viability and increased in apoptotic cell death under oxidative stress. Collectively, Usp18 protects the cells from oxidative stress-induced apoptosis which may be through the regulation of p53 and caspase 3..
18. Ka Fai William Tse, Importance of deubiquitinases in zebrafish craniofacial development, Biochemical and Biophysical Research Communications, 10.1016/j.bbrc.2017.04.132, 487, 4, 813-819, 2017.06, Deconjugation of ubiquitin and/or ubiqutin-like modified substrates is essential to maintain a sufficient free ubiquitin within the cell. Deubiquitinases (DUBs) play a key role in the process. Besides, DUBs also play several important regulatory roles in cellular processes. However, our knowledge of their developmental roles are limited. The report here aims to study their potential roles in craniofacial development. Based on the previous genome-wide study in 2009, we selected 36 DUBs to perform the morpholino (MO) knockdown in this study, followed by the Alcian blue cartilage staining at 5 days post-fertilization (dpf) larvae to investigate the facial development. Results classified the tested DUBs into three groups, in which 28% showed unchanged phenotype (Class 1); 22% showed mild changes on the branchial arches (Class 2A); 31% had malformation on branchial arches and ethmoid plate (Class 2B); and 19% had severe changes in most of the facial structures (Class 3). Lastly, we used uchl3 morphant as an example to show that our screening data could be useful for further functional studies. To summarize, we identified new craniofacial developmental role of 26 DUBs in the zebrafish..
19. Henry C.H. Fong, Jeff C.H. Ho, Angela H.Y. Cheung, K. P. Lai, Ka Fai William Tse, Developmental toxicity of the common UV filter, benophenone-2, in zebrafish embryos, Chemosphere, 10.1016/j.chemosphere.2016.08.073, 164, 413-420, 2016.12, Benozophenone (BP) type UV filters are extensively used in the personal care products to provide protection against the harmful effects of UV radiation. BPs are one of the primary components in the UV filter family, in which benophenone-2 (BP2) is widely used as a UV filter reagent in the sunscreen. Humans used these personal care products directly on skin and the chemicals will be washed away to the water system. BP2 has been identified as one of the endocrine disruptor chemicals, which can inference the synthesis, metabolism, and action of endogenous hormones. Environmentally, it has been found to contaminate water worldwide. In this study, we aimed to unfold the possible developmental toxicology of this chemical. Zebrafish are used as the screening model to perform in situ hybridization staining to investigate the effects of BP2 on segmentation, brain regionalization, and facial formation at four developmental stages (10–12 somite, prim-5, 2 and 5 days post-fertilization). Results showed 40 μM (9.85 mg L<sup>−1</sup>) or above BP2 exposure in zebrafish embryos for 5 days resulted in lipid accumulation in the yolk sac and facial malformation via affecting the lipid processing and the expression of cranial neural crest cells respectively. To conclude, the study alarmed its potential developmental toxicities at high dosage exposure..
20. Ka Fai William Tse, Treacher Collins syndrome
New insights from animal models, International Journal of Biochemistry and Cell Biology, 10.1016/j.biocel.2016.10.016, 81, 44-47, 2016.12, Treacher Collins syndrome (TCS, OMIM: 154500), an autosomal-dominant craniofacial developmental syndrome that occurs in 1 out of every 50,000 live births, is characterized by craniofacial malformation. Mutations in TCOF1, POLR1C, or POLR1D have been identified in affected individuals. In addition to established mouse models, zebrafish models have recently emerged as an valuable method to study facial disease. In this report, we summarized the two updated articles working on the pathogenesis of the newly identified polr1c and polr1d TCS mutations (Lau et al., 2016; Noack Watt et al., 2016) and discussed the possibility of using the anti-oxidants to prevent or rescue the TCS facial phenotype (Sakai et al., 2016). Taken together, this article provides an update on the disease from basic information to pathogenesis, and further summarizes the suggested therapies from recent laboratory research..
21. Ka Fai William Tse, Jing Woei Li, Anna Chung Kwan Tse, Ting Fung Chan, Jeff Cheuk Hin Ho, Rudolf Shiu Sun Wu, Chris Kong Chu Wong, Keng Po Lai, Fatty liver disease induced by perfluorooctane sulfonate
Novel insight from transcriptome analysis, Chemosphere, 10.1016/j.chemosphere.2016.05.060, 159, 166-177, 2016.09, Perfluorooctane sulfonate (PFOS), a hepato-toxicant and potential non-genotoxic carcinogen, was widely used in industrial and commercial products. Recent studies have revealed the ubiquitous occurrence of PFOS in the environment and in humans worldwide. The widespread contamination of PFOS in human serum raised concerns about its long-term toxic effects and its potential risks to human health. Using fatty liver mutant foie gras (fgr<sup>-/-</sup>)/transport protein particle complex 11 (trappc11<sup>-/-</sup>) and PFOS-exposed wild-type zebrafish embryos as the study model, together with RNA sequencing and comparative transcriptomic analysis, we identified 499 and 1414 differential expressed genes (DEGs) in PFOS-exposed wild-type and trappc11 mutant zebrafish, respectively. Also, the gene ontology analysis on common deregulated genes was found to be associated with different metabolic processes such as the carbohydrate metabolic process, glycerol ether metabolic process, mannose biosynthetic process, de novo' (Guanosine diphosphate) GDP-l-fucose biosynthetic process, GDP-mannose metabolic process and galactose metabolic process. Ingenuity Pathway Analysis further highlighted that these deregulated gene clusters are closely related to hepatitis, inflammation, fibrosis and cirrhosis of liver cells, suggesting that PFOS can cause liver pathogenesis and non-alcoholic fatty liver disease in zebrafish. The transcriptomic alterations revealed may serve as biomarkers for the hepatotoxic effect of PFOS..
22. Marco Chi Chung Lau, Ernest Man Lok Kwong, Keng Po Lai, Jing Woei Li, Jeff Cheuk Hin Ho, Ting Fung Chan, Chris Kong Chu Wong, Yun Jin Jiang, Ka Fai William Tse, Pathogenesis of POLR1C-dependent Type 3 Treacher Collins Syndrome revealed by a zebrafish model, Biochimica et Biophysica Acta - Molecular Basis of Disease, 10.1016/j.bbadis.2016.03.005, 1862, 6, 1147-1158, 2016.06, Treacher Collins Syndrome (TCS) is a rare congenital birth disorder (1 in 50,000 live births) characterized by severe craniofacial defects, including the downward slanting palpebral fissures, hypoplasia of the facial bones, and cleft palate (CP). Over 90% of patients with TCS have a mutation in the TCOF1 gene. However, some patients exhibit mutations in two new causative genes, POLR1C and POLR1D, which encode subunits of RNA polymerases I and III, that affect ribosome biogenesis. In this study, we examine the role of POLR1C in TCS using zebrafish as a model system. Our data confirmed that polr1c is highly expressed in the facial region, and dysfunction of this gene by knockdown or knock-out resulted in mis-expression of neural crest cells during early development that leads to TCS phenotype. Next generation sequencing and bioinformatics analysis of the polr1c mutants further demonstrated the up-regulated p53 pathway and predicted skeletal disorders. Lastly, we partially rescued the TCS facial phenotype in the background of p53 mutants, which supported the hypothesis that POLR1C-dependent type 3 TCS is associated with the p53 pathway..
23. Jeff C.H. Ho, C. D. Hsiao, K. Kawakami, Ka Fai William Tse, Triclosan (TCS) exposure impairs lipid metabolism in zebrafish embryos, Aquatic Toxicology, 10.1016/j.aquatox.2016.01.001, 173, 29-35, 2016.04, Triclosan (TCS) is an active antimicrobial ingredient used in many household products, such as skin creams and toothpaste. It is produced in high volumes, and humans are directly exposed to it and dispose it on a daily basis. TCS has been found to contaminate water worldwide. This study aimed to understand the potential developmental and metabolic abnormalities caused by TCS exposure by using zebrafish as the experimental model. Four developmental stages (70-85% epiboly, 10-12 somite, prim-5, and 5dpf) were selected to perform in situ hybridization staining to investigate the effects of TCS on dorsal ventral patterning, segmentation, brain development, and organ formation. Results showed, in terms of developmental toxicology, that neither phenotypic nor molecular changes were found after 5 days of 250. μg/L TCS exposure. However, such dosage of TCS exposure resulted in lipid droplet accumulation in the yolk sac, which might due to the deregulated mRNA expression level of beta-oxidation transcripts. This study showed that 250. μg/L TCS exposure does not affect normal embryogenesis or organogenesis; however, there are concerns regarding possible impairment of lipid metabolism..
24. Keng Po Lai, Jing Woei Li, Je Gu, Ting Fung Chan, Ka Fai William Tse, Chris Kong Chu Wong, Transcriptomic analysis reveals specific osmoregulatory adaptive responses in gill mitochondria-rich cells and pavement cells of the Japanese eel, BMC Genomics, 10.1186/s12864-015-2271-0, 16, 1, 2015.12, Background: Homeostasis of ions and water is important for the maintenance of cellular functions. The regulation of the homeostasis is particularly important in euryhaline fish that migrate between freshwater (FW) and seawater (SW) environments. The fish gill, the major tissue that forms an interface separating the extracellular fluids and external water environment, has an effective transport system to maintain and regulate a constant body osmolality. In fish gills, the two major epithelial cells, pavement cells (PVCs) and mitochondria-rich cells (MRCs), are known to play key and complementary roles in ion transport at the interface. Discovering the robust mechanisms underlying the two cell types' response to osmotic stress would benefit our understanding of the fundamental mechanism allowing PVCs and MRCs to handle osmotic stress. Owing to the limited genomic data available on estuarine species, existing knowledge in this area is slim. In this study, transcriptome analyses were conducted using PVCs and MRCs isolated from Japanese eels adapted to FW or SW environments to provide a genome-wide molecular study to unravel the fundamental processes at work. Results: The study identified more than 12,000 transcripts in the gill cells. Interestingly, remarkable differential expressed genes (DEGs) were identified in PVCs (970 transcripts) instead of MRCs (400 transcripts) in gills of fish adapted to FW or SW. Since PVCs cover more than 90% of the gill epithelial surface, the greater change in gene expression patterns in PVCs in response to external osmolality is anticipated. In the integrity pathway analysis, 19 common biological functions were identified in PVCs and MRCs. In the enriched signaling pathways analysis, most pathways differed between PVCs and MRCs; 14 enriched pathways were identified in PVCs and 12 in MRCs. The results suggest that the osmoregulatory responses in PVCs and MRCs are cell-type specific, which supports the complementary functions of the cells in osmoregulation. Conclusions: This is the first study to provide transcriptomic analysis of PVCs and MRCs in gills of eels adapted to FW or SW environments. It describes the cell-type specific transcriptomic network in different tonicity. The findings consolidate the known osmoregulatory pathways and provide molecular insight in osmoregulation. The presented data will be useful for researchers to select their targets for further studies..
25. Chia Hao Hsu, Ji Sheng Lin, Keng Po Lai, Jing Woei Li, Ting Fung Chan, May Su You, Ka Fai William Tse, Yun Jin Jiang, A new mib allele with a chromosomal deletion covering foxc1a exhibits anterior somite specification defect, Scientific Reports, 10.1038/srep10673, 5, 2015.06, mib nn2002, found from an allele screen, showed early segmentation defect and severe cell death phenotypes, which are different from previously known mib mutants. Despite distinct morphological phenotypes, the typical mib molecular phenotypes: her4 down-regulation, neurogenic phenotype and cold sensitive dlc expression pattern, still remained. The linkage analysis also indicated that mib nn2002 is a new mib allele. Failure of specification in anterior 7-10 somites is likely due to lack of foxc1a expression in mib nn2002 homozygotes. Somites and somite markers gradually appeared after 7-10 somite stage, suggesting that foxc1a is only essential for the formation of anterior 7-10 somites. Apoptosis began around 16-somite stage with p53 up-regulation. To find the possible links of mib, foxc1a and apoptosis, transcriptome analysis was employed. About 140 genes, including wnt3a, foxc1a and mib, were not detected in the homozygotes. Overexpression of foxc1a mRNA in mib nn2002 homozygotes partially rescued the anterior somite specification. In the process of characterizing mib nn2002 mutation, we integrated the scaffolds containing mib locus into chromosome 2 (or linkage group 2, LG2) based on synteny comparison and transcriptome results. Genomic PCR analysis further supported the conclusion and showed that mib nn2002 has a chromosomal deletion with the size of about 9.6 Mbp..
26. Ka Fai William Tse, Jin Sun, Huoming Zhang, Keng Po Lai, Jie Gu, Alice Yu Sheung Law, Bonnie Ho Yee Yeung, Sheung Ching Chow, Jian Wen Qiu, Chris Kong Chu Wong, Data for transcriptomic and iTRAQ proteomic analysis of Anguilla japonica gills in response to osmotic stress, Data in Brief, 10.1016/j.dib.2015.02.012, 3, 120-125, 2015.06, This article contains data related to the two research articles titled Transcriptomic and iTRAQ proteomic approaches reveal novel short-term hyperosmotic stress responsive proteins in the gill of the Japanese eel (Anguilla japonica) (Tse et al. [1]) and iTRAQ-based quantitative proteomic analysis reveals acute hypo-osmotic responsive proteins in the gills of the Japanese eel (Anguilla japonica) (Tse et al. [2]). The two research articles show the usefulness of combining transcriptomic and proteomic approaches to provide molecular insights of osmoregulation mechanism in a non-model organism, the Japanese eel. The information presented here combines the raw data from the two studies and provides an overview on the physiological functions of fish gills..
27. Jie Gu, Jing Woei Li, Ka Fai William Tse, Ting Fung Chan, Keng Po Lai, Chris Kong Chu Wong, Transcriptomic responses of corpuscle of Stannius gland of Japanese eels (Anguilla japonica) to Changes in Water Salinity, Scientific Reports, 10.1038/srep09836, 5, 2015.04, Physiological studies of a unique endocrine gland in fish, named corpuscles of Stannius (CS), described a Ca2 + -regulatory function for this gland mediated by stanniocalcin-1, a hypocalcemic polypeptide hormone. However, to date, the endocrine functions of the glands have not been completely elucidated.We hypothesized that other unidentified active principles in the glands are involved in the regulation of plasma ion (Na +, Ca2 +) and/or blood pressure. In this study, transcriptome sequencing of CS glands was performed using Japanese eels (Anguilla japonica) adapted to freshwater (FW) or seawater (SW) to reveal the presence and differential expression of genes encoding proteins related to the ion-osmoregulatory and pressor functions. We acquired a total of 14.1 Mb and 12.1 Mb quality-trimmed reads from the CS glands collected from FW and SW adapted eels, respectively. The de novo assembly resulted in 9254 annotated genes. Among them, 475 genes were differentially expressed with 357 up- and 118 down-regulated in the SW group. Gene ontology analysis further demonstrated the presence of natriuresis and pressor related genes. In summary, ours is the first study using high-throughput sequencing to identify gene targets that could explain the physiological importance of the CS glands..
28. Keng P.o. Lai, Jing Woei Li, Simon Y.uan Wang, Jill Ying Chiu, Anna Tse, Karen Lau, Si Lok, Doris Ting Au, Ka Fai William Tse, Chris Chu Wong, Ting Fung Chan, Richard Y.uen Chong Kong, Rudolf S.hiu Sun Wu, Tissue-specific transcriptome assemblies of the marine medaka Oryzias melastigma and comparative analysis with the freshwater medaka Oryzias latipes, BMC Genomics, 10.1186/s12864-015-1325-7, 16, 2015.01, BACKGROUND: The marine medaka Oryzias melastigma has been demonstrated as a novel model for marine ecotoxicological studies. However, the lack of genome and transcriptome reference has largely restricted the use of O. melastigma in the assessment of in vivo molecular responses to environmental stresses and the analysis of biological toxicity in the marine environment. Although O. melastigma is believed to be phylogenetically closely related to Oryzias latipes, the divergence between these two species is still largely unknown. Using Illumina high-throughput RNA sequencing followed by de novo assembly and comprehensive gene annotation, we provided transcriptomic resources for the brain, liver, ovary and testis of O. melastigma. We also investigated the possible extent of divergence between O. melastigma and O. latipes at the transcriptome level.
RESULTS: More than 14,000 transcripts across brain, liver, ovary and testis in marine medaka were annotated, of which 5880 transcripts were orthologous between O. melastigma and O. latipes. Tissue-enriched genes were identified in O. melastigma, and Gene Ontology analysis demonstrated the functional specificity of the annotated genes in respective tissue. Lastly, the identification of marine medaka-enriched transcripts suggested the necessity of generating transcriptome dataset of O. melastigma.
CONCLUSIONS: Orthologous transcripts between O. melastigma and O. latipes, tissue-enriched genes and O. melastigma-enriched transcripts were identified. Genome-wide expression studies of marine medaka require an assembled transcriptome, and this sequencing effort has generated a valuable resource of coding DNA for a non-model species. This transcriptome resource will aid future studies assessing in vivo molecular responses to environmental stresses and those analyzing biological toxicity in the marine environment..
29. Ka Fai William Tse, Jin Sun, Huoming Zhang, Keng Po Lai, Jie Gu, Jian Wen Qiu, Chris Kong Chu Wong, ITRAQ-based quantitative proteomic analysis reveals acute hypo-osmotic responsive proteins in the gills of the Japanese eel (Anguilla japonica), Journal of Proteomics, 10.1016/j.jprot.2014.01.025, 105, 133-143, 2014.06, Osmoregulation in fish has been a classical research topic for several decades. Salmon and eels are the widely used model animals because of their wide distribution in different geographical locations and spawning migration between fresh- and salt-water habitats. Numerous fish osmoregulatory hormones and ion transporters were identified for their essential roles in acclimation and adaptation to waters of different salinities. Because of the lack of a genomic database, the scope of most studies, however, is very limited. Recently, our group reported the first high-throughput transcriptomic and proteomic studies to identify hyperosmotic-responsive genes/proteins in gills of Japanese eels. In this study, we aimed to decipher changes in hypo-osmotic-responsive proteins in fish acclimating from seawater (SW) to freshwater (FW) conditions. We collected gill samples from SW-adapted and SW-to-FW-acclimating fish. The respective gill proteins were extracted and labeled using isobaric tags for relative and absolute quantitation (iTRAQ) and analyzed using a high-resolution mass spectrometer. In the short-term transfer from SW to FW, 51 hypo-responsive proteins were detected, and 24 unique hypo-osmotic-responsive proteins were identified (15 up-regulated and nine down-regulated proteins). Our data support the use of an omics approach to facilitate the application of functional genomics in non-model organisms. Biological significance: By combining transcriptomic and proteomic approaches, the study has provided the most comprehensive, targeted investigation of eel gill hypo-osmotic responsive proteins that provides molecular insights of osmoregulation mechanisms in a non-model organism, eel. This article is part of a Special Issue entitled: Proteomics of non-model organisms..
30. Ka Fai William Tse, The use of whole mount in situ hybridization screening to understand the developmental toxicology of environmental pollutants in zebrafish embryos, Zebrafish: Topics in Reproduction, Toxicology and Development, 215-224, 2014.04, Zebrafish have been widely used in developmental studies as an excellent in vivo, high-throughput and scalable system for decades, due to the following advantages. Its small size (< 5mm at 7 days post-fertilization (dpf)) and large number of rapidly developing transparent embryos (most organs are developed within 5dpf) enable researchers to undergo whole mount in situ hybridization studies, real-time fate-mapping experiments, and visualizing developing organ morphology. Furthermore, the zebrafish has a well-established genome database that provides information for genomic studies, ranging from microarrays to more advance deep-sequencing studies. Moreover, its highly conserved developmental signalling pathways position it as a good model to correlate with other mammalian studies. In the field of environmental toxicology, zebrafish is used to understand the common and standard toxicology end point, such as phenotypic changes and lethal concentrations (LC50). However, these studies do not fully utilize the features of zebrafish. This chapter aims to provide our experiences and opinion on using zebrafish to understand early developmental defects caused by toxicant exposures. A standard whole-mount in situ hybridization screening protocol was used to monitor three critical early developmental stages (60-75% epiboly, 8-10 somite, and prim-5). The screening provided first-hand information of whether the toxicant affects the dorsoventral (DV) patterning, segmentation, and brain development in zebrafish embryos within 24 hours exposure of toxicants. Since tracing the continuous developmental changes at different stages of mammalian embryos is not easy due to in utero development; the zebrafish provides an excellent alternative way to understand the developmental toxicology of different toxicants..
31. Ka Fai William Tse, The role of osmotic stress transcription factor 1 in fishes, Frontiers in Zoology, 10.1186/s12983-014-0086-5, 11, 1, 2014, Osmotic stress transcription factor 1 (Ostf1) was first discovered by subtractive hybridization in the gills of Mozambique tilapia (Oreochromis mossambicus) transferred from fresh water (FW) to seawater (SW). It is a putative transcriptional regulator and the "early hyperosmotic regulated protein". In the 2 hours after FW to SW transfer, ostf1 mRNA levels increase six fold. It is believed that, as a fast-response gene, Ostf1 plays a critical role in fish osmoregulation. Since its discovery, numerous studies have been performed to understand the nature and osmoregulatory mechanism of Ostf1. A decade has passed since the discovery of Ostf1, and it is a good time to summarize our current understanding of this gene. Different fish models have been used to study Ostf1, which is not limited to the traditional euryhaline fishes, such as eels and tilapia. Ostf1 can be found in modern fish models such as medaka and zebrafish. This review covers and summarizes the findings from different fishes, and provides a perspective for future Ostf1 studies..
32. George Kamel, Tatiana Hoyos, Lucie Rochard, Max Dougherty, Yawei Kong, Ka Fai William Tse, Valeriy Shubinets, Michael Grimaldi, Eric C. Liao, Requirement for frzb and fzd7a in cranial neural crest convergence and extension mechanisms during zebrafish palate and jaw morphogenesis, Developmental Biology, 10.1016/j.ydbio.2013.06.012, 381, 2, 423-433, 2013.09, Regulation of convergence and extension by wnt-frizzled signaling is a common theme in embryogenesis. This study examines the functional requirements of frzb and fzd7a in convergence and extension mechanisms during craniofacial development. Using a morpholino knockdown approach, we found that frzb and fzd7a are dispensable for directed migration of the bilateral trabeculae, but necessary for the convergence and extension of the palatal elements, where the extension process is mediated by chondrocyte proliferation, morphologic change and intercalation. In contrast, frzb and fzd7a are required for convergence of the mandibular prominences, where knockdown of either frzb or fzd7a resulted in complete loss of lower jaw structures. Further, we found that bapx1 was specifically downregulated in the wnt9a/. frzb/. fzd7a morphants, while general neural crest markers were unaffected. In addition, expression of wnt9a and frzb was also absent in the edn-/- mutant. Notably, over-expression of bapx1 was sufficient to partially rescue mandibular elements in the wnt9a/. frzb/. fzd7a morphants, demonstrating genetic epistasis of bapx1 acting downstream of edn1 and wnt9a/. frzb/. fzd7a in lower jaw development. This study underscores the important role of wnt-frizzled signaling in convergence and extension in palate and craniofacial morphogenesis, distinct regulation of upper vs. lower jaw structures, and integration of wnt-frizzled with endothelin signaling to coordinate shaping of the facial form..
33. Ka Fai William Tse, Jin Sun, Huoming Zhang, Alice Yu Sheung Law, Bonnie Ho Yee Yeung, Sheung Ching Chow, Jian Wen Qiu, Chris Kong Chu Wong, Transcriptomic and iTRAQ proteomic approaches reveal novel short-term hyperosmotic stress responsive proteins in the gill of the Japanese eel (Anguilla japonica), Journal of Proteomics, 10.1016/j.jprot.2013.05.026, 89, 81-94, 2013.08, Osmoregulation is critical for the survival of fishes that migrate between freshwater (FW) and seawater (SW). The eel, as a catadromous fish, has been studied for decades to reveal the mechanisms of osmoregulation. These studies, however, have been limited by the lack of a genomic database to decipher the mechanism of osmoregulation at a molecular level. In this study, using high-throughput transcriptomic and proteomic technologies, we have provided the first genome-wide study to identify hyperosmotic responsive proteins in the gills of the Japanese eel. Deep sequencing using the 454 platform produced over 660,000 reads with a mean length of 385. bp. For the proteomic study, we collected gill samples from three different treatment groups of fish that had fully adapted to FW/SW or were transferred from FW to SW for 6. h. The respective group of gill proteins were extracted and labeled using an isobaric tag for relative and absolute quantitation (iTRAQ) using LTQ-Orbitrap, a high resolution mass spectrometer. Among the 1519 proteins identified from the gill samples, 96 proteins were differentially expressed between FW and SW adapted fish. Nineteen hyperosmotic responsive proteins were detected (10 up-regulated and 9 down-regulated proteins) after 6. h post FW to SW transfer. Biological significance: The study has provided the most comprehensive, targeted investigation of eel gill proteins to date, and shown the powerfulness of combining transcriptomic and proteomic approaches to provide molecular insights of osmoregulation mechanisms in a non-model organism, eel..
34. Ka Fai William Tse, Yun Jin Jiang, Chris Kong Chu Wong, Zebrafish transforming growth factor-β-stimulated clone 22 domain 3 (TSC22D3) plays critical roles in Bmp-dependent dorsoventral patterning via two deubiquitylating enzymes Usp15 and Otud4, Biochimica et Biophysica Acta - General Subjects, 10.1016/j.bbagen.2013.05.006, 1830, 10, 4584-4593, 2013.07, Background Osmotic stress transcription factor 1/transforming growth factor-β-stimulated clone 22 domain 3 (Ostf1/Tsc22d3) is a transcription factor that plays an osmoregulatory role in euryhaline fishes. Its mRNA and protein levels are up-regulated under hyperosmotic stress. However, its osmoregulatory and developmental functions have not been studied in any stenohaline freshwater fishes. Zebrafish is an excellent model to perform such study to unfold the functional role of Tsc22d3. Methods We identified the zebrafish Tsc22d3 and performed knockdown studies using morpholino antisense oligonucleotide (MO). Results Zebrafish Tsc22d3 did not response to hypertonic stress and ts22d3 knockdown or overexpression by injecting MO or capped RNA did not change the transcriptional levels of any of the known ionocyte markers. To reveal the unknown function of zebrafish Tsc22d3, we performed several in situ molecular marker studies on tsc22d3 morphants and found that Tsc22d3 plays multi-functional roles in dorsoventral (DV) patterning, segmentation, and brain development. We then aimed to identify the mechanism of Tsc22d3 in the earliest stages of DV patterning. Our results demonstrated that tsc22d3 is a ventralizing gene that can stimulate the transcription of bone morphogenetic protein 4 (bmp4) and, thus, has a positive effect on the Bmp signaling pathway. Furthermore, we showed that Tsc22d3 interacts with deubiquitylating enzymes, ubiquitin-specific protease 15 (Usp15) and ovarian tumor domain containing protein 4 (Otud4). In addition, the interruption of Bmp4 signaling by double knockdown of usp15 and otud4 reduced the ventralized effects in tsc22d3-overexpressing embryos. Conclusions This is the first study to identify new developmental functions of Tsc22d3 in zebrafish. General significance Zebrafish tsc22d3 is a ventralizing gene and plays a role in early embryogenesis..
35. S. C. Chow, Ka Fai William Tse, Chris K C Wong, Dexamethasone (DEX) induces osmotic stress transcription factor 1 (Ostf1) through the Akt-GSK3β pathway in freshwater Japanese eel gill cell cultures, Biology Open, 10.1242/bio.20134135, 2, 5, 487-491, 2013.05, Osmosensing and osmoregulatory processes undertaken in gills of euryhaline fish are coordinated by integrative actions of various signaling molecules/transcriptional factors. Considerable numbers of studies report the hyper- and hypoosmoregulatory functions of fish gills, by illustrating the process of gill cell remodeling and the modulation of the expression of ion channels/transporters. Comparatively mechanistic information relayed from signal integration to transcriptional regulation in mediating gill cell functions has not yet been elucidated. In this study we demonstrate the functional links from cortisol stimulation, to Akt activation, to the expression of the transcriptional factor, Ostf1. Using the synthetic glucocorticoid receptor agonist, dexamethasone (DEX), Ostf1 expression is found to be activated via glucocorticoid receptor (GR) and mediated by the Akt-GSK3β signaling pathway. Pharmacological experiments using kinase inhibitors reveal that the expression of Ostf1 is negatively regulated by Akt activation. The inhibition of PI3K or Akt activities, by the specific kinase inhibitors (wortmannin, LY294002 or SH6), stimulates Ostf1 expression, while a reduction of GSK3β activity by LiCl reduces Ostf1 expression. Collectively, our report for the first time indicates that DEX can induce Ostf1 via GR, with the involvement of the Akt-GSK3β signaling pathway in primary eel gill cell cultures. The data also suggest that Ostf1 may play different roles in gill cell survival during seawater acclimation..
36. Ka Fai William Tse, Bonnie H.Y. Yeung, H. T. Wan, Chris K.C. Wong, Early embryogenesis in zebrafish is affected by bisphenol A exposure, Biology Open, 10.1242/bio.20134283, 2, 5, 466-471, 2013.05, Exposure of a developing embryo or fetus to endocrine disrupting chemicals (EDCs) has been hypothesized to increase the propensity of an individual to develop a disease or dysfunction in his/her later life. Although it is important to understand the effects of EDCs on early development in animals, sufficient information about these effects is not available thus far. This is probably because of the technical difficulties in tracing the continuous developmental changes at different stages of mammalian embryos. The zebrafish, an excellent model currently used in developmental biology, provides new insights to the field of toxicological studies. We used the standard whole-mount in situ hybridization screening protocol to determine the early developmental defects in zebrafish embryos exposed to the ubiquitous pollutant, bisphenol A (BPA). Three stages (60-75% epiboly, 8-10 somite, and prim-5) were selected for in situ screening of different molecular markers, whereas BPA exposure altered early dorsoventral (DV) patterning, segmentation, and brain development in zebrafish embryos within 24 hours of exposure..
37. K. P. Lai, Alice Y.S. Law, Marco C.C. Lau, Y. Takei, Ka Fai William Tse, Chris K.C. Wong, Osmotic stress transcription factor 1b (Ostf1b) promotes migration properties with the modulation of epithelial mesenchymal transition (EMT) phenotype in human embryonic kidney cell, International Journal of Biochemistry and Cell Biology, 10.1016/j.biocel.2013.05.023, 45, 8, 1921-1926, 2013.01, Osmoregulation is an essential mechanism for euryhaline fish. Gill cells undergo rapid mechanism to maintain the cellular homeostasis during osmotic stress. Reports have suggested that gill cells may be able to migrate between primary filament and secondary lamella during seawater acclimination. However, the factor that can trigger such process is not well-known. Previously, we identified the osmotic stress transcription factor 1b (Ostf1b) in medaka and found that it is an early hypertonic responsive gene and can activate the c-Jun N-terminal kinase (JNK) pathway. In this report, we aim to know if Ostf1b plays the role in the migration. Ostf1b was ectopic expressed in the human embryonic kidney cell line (HEK293) to understand the Ostf1b function. Results clearly demonstrated that Ostf1b could constitutively activate the Rho kinase 1 (ROCK1) and myosin light chain 2 (MLC2) signalling pathway that promotes cell migration, epithelial mesenchymal transition (EMT) and cytoskeletal dynamics through stress fibre formation. The study supports the notion of cell migration and cytoskeleton rearrangement theories in osmoregulation..
38. Ka Fai William Tse, Sheung C. Chow, Chris K C Wong, Eel osmotic stress transcriptional factor 1 (Ostf1) is highly expressed in gill mitochondria-rich cells, where ERK phosphorylated, Frontiers in Zoology, 10.1186/1742-9994-9-3, 9, 2012.03, Background: Osmotic stress transcriptional factor 1 (Ostf1) was firstly identified in tilapia in 2005. Then numerous studies have investigated its regulation and expression profile in fish gill tissues in related to osmoregulation. Generally, hyperosmotic stress induced ostf1 mRNA expression level, however there is no report studying the cellular localization of Ostf1 expression in any osmoregulatory tissue. In this study immunohistochemical (IHC) approach was used to study the cellular localization of Ostf1 in gill cells of Japanese eels.Findings: Ostf1 protein was found to be localized in branchial mitochondria-rich/chloride cell (MRC/CC) as revealed by Naα5 and CFTR co-localization. The protein was detectable at day 3 after fresh water to seawater transfer and was mainly localized in MRCs. Moreover, elevated levels of extracellular signal regulated kinase (ERK) phosphorylation was observed at day 3 of the transfer and was co-localized with MRCs.Conclusions: Our data identified Ostf1 expression in gill MRCs. The observation supports the role of Ostf1 in osmosensing and/or osmoregulation in fish gills, particularly its functional relationship with MRCs. The observation of the co-expression of pERK and Ostf1 in MRCs suggests a cross-talk mechanism between the mitogen-activated protein kinases (MAPKs) and Ostf1 in response to hyperosmotic challenge. To summarize, this report has addressed the cellular localization of Ostf1 and provides evidence to illustrate the involvement of Ostf1 and ERK on osmosensing and osmoregulatory function of gill MRCs..
39. Ka Fai William Tse, Yun Jin Jiang, Functional screen of zebrafish deubiquitylating enzymes by morpholino knockdown and in situ hybridization, Functional Genomics Methods and Protocols, 10.1007/978-1-61779-424-7_24, 815, 321-331, 2012.01, In order to unfold the function of genes, solely performing mRNA over-expression is not enough nowadays. Traditional protein expression experiments, such as Western blotting and immunohistochemical staining, could only provide researchers the changes of expression levels and/or location of their targets. To make a more strong and convincing statement about gene function, it is necessary to perform both "gain-of-function" and "loss-of-function" studies. Both assays can be performed easily by transfecting DNA plasmid and siRNA in cell culture system; while in zebrafish, mRNA and morpholino (MO) microinjection can serve similar purposes. It is common for the zebrafish community to carry out microinjection experiments to explore a gene function. Instead of making a single knockdown/over-expression of a gene, we foresee that more and more large-scale screens on certain protein families will be performed in the future. Here, based on our previous experience in zebrafish "loss-of-function" screening on deubiquitylating enzymes, we describe a general work flow, from morpholino designation, in situ hybridization, to data analysis, as a reference for researchers who may be interested in a similar screen..
40. Ka Fai William Tse, Chris Kong Chu Wong, Modulation of gene transcriptional level of different ion transporters in eel gill mitochondria-rich cells upon osmotic stress, Eels: Physiology, Habitat and Conservation, 133-148, 2012, Eels are euryhaline fishes that their life cycles involve the stay in fresh water and seawater. In order to compensate the osmotic challenges in fresh water (ion loss and water gain) and in seawater habitat (ion gain and water loss), eels have developed specific osmoregulatory mechanisms to acclimate rapidly and effectively in such two extreme aquatic environments. Fish gill is the outermost tissue that is in direct contact with the external media. In the gill tissue, two specific osmoregulatory cell types (pavement cells (PVCs) and mitochondria-rich/chloride cells (MRCs/CCs)) have been identified and characterized. It is generally believed that MRCs, which we will focus on, are the essential ion-regulatory cell type in the eel gill. With the recent advances in molecular biology, together with the immunohistochemical staining and electrophysiology studies, more transcriptional and translational profiling data are generated to unfold the molecular nature of the branchial osmoregulatory mechanisms. In this review, we will begin with the general description of eel gill structure and cell types (PVCs and MRCs), followed by the discussion on the differential mRNA expressions of different ion transporters in MRCs under hyper/ hypo- tonic stress conditions. Lastly, we will provide an opinion on the use of recent advanced genomic transcriptome data to form a public accessible database. To summarize, this chapter provides essential updated information on the expressions of ion channels/ transporters in eel gills acclimated in waters of different salinities, providing new in-sight on the future direction of eel gill studies in modern molecular perspectives..
41. Ka Fai William Tse, K. P. Lai, Y. Takei, Medaka osmotic stress transcription factor 1b (Ostf1b/TSC22D3-2) triggers hyperosmotic responses of different ion transporters in medaka gill and human embryonic kidney cells via the JNK signalling pathway, International Journal of Biochemistry and Cell Biology, 10.1016/j.biocel.2011.08.013, 43, 12, 1764-1775, 2011.12, Eukaryotic cells undergo rapid regulatory processes to maintain cellular homeostasis upon osmotic stress. In fishes, gill epithelial cells play main roles in these processes. Although osmoregulatory functions of fish gills have been well studied, little is known about the underlying mechanisms, particularly the hypertonic-induced signalling pathways during osmotic stress. This study reports for the first time on the osmo-sensing signal cascade that related to the medaka osmotic stress transcription factor 1 (Ostf1), a hypertonic induced immediate early gene, under hypertonic stress. Quantitative real-time PCR showed the rapid increase of Ostf1 in gill after transfer of medaka from fresh water to 50% seawater; particularly Ostf1b whose mRNA expression increased to 4 folds at 0.5 h and reached to 10 folds at 6 h after the transfer. The in vivo knockdown of Ostf1b profoundly inhibited SEK and JNK phosphorylation, but not p38 and ERK phosphorylation in the medaka gill tissue. To further investigate the possible role of Ostf1b in the JNK pathway, Ostf1b was ectopically expressed in HEK293 cells. Results indicated that Ostf1b is a downstream target of SEK and JNK and exerts a positive feedback loop on the JNK signalling pathway via activation of GCK and/or MLK3 proteins. Additionally, MAPK inhibitors experiments suggested that activation of the JNK pathway by hypertonicity is involved in the maintenance of Ostf1b stability, which in turn provides continuous stimulation of GCK for JNK phosphorylation. Lastly, changes in transcription levels of different water/ion transporters were found in knockdown or ecoptic over-expression of Ostf1b in medaka gills and human embryonic kidney cells, suggesting the role of Ostf1b in modulation of critical water channel/ion transporters during osmotic stress..
42. Ka Fai William Tse, S. C. Chow, K. P. Lai, D. W T Au, Chris K C Wong, Modulation of ion transporter expression in gill mitochondrion-rich cells of eels acclimated to low-Na+ or-Cl- freshwater, Journal of Experimental Zoology Part A: Ecological Genetics and Physiology, 10.1002/jez.681, 315 A, 7, 385-393, 2011.08, In this study, we aimed to establish an experimental model to study the role of the gill mitochondrion-rich cells (MRCs) of freshwater fish in Na+ uptake and to examine the effect of adjusting external Na+ and Cl- ions on selected ion transporters in gill MRCs. Japanese eels (Anguilla japonica) acclimated to deionized (DI) water for 2 weeks were transferred directly to (a) ion-supplemented artificial freshwater (AF), (b) Na+-deficient AF, or (c) Cl--deficient AF for 2 days. The effects of the transfer on the expression levels of ion transporters in isolated gill cells were investigated. Our data demonstrated that the 2-day acclimation in ion-supplemented AF, Na+-deficient AF, or Cl--deficient AF led to a significant increase in serum osmolarity attributed mainly to an increase in serum Na+ and/or Cl- levels when compared with DI-acclimated eel. Significant inductions of V-type H+-ATPase (V-H+-ATPase) and cotransporter (NBC1) mRNA expression in gill MRCs were detected in AF-acclimated fish. In fish acclimated to Na+-deficient AF, mRNA expression levels of V-H+-ATPase, NBC1, and Na+/H+-exchanger-3 (NHE3) were significantly increased in MRCs. Fish acclimated to Cl--deficient AF showed no observable change in expression levels of ion transporters in gill MRCs. In addition, expression levels of ion transporters in pavement cells were stable throughout the 2-day experiments. These data indicate that the level of Na+ in freshwater is important for altering the mRNA expression of ion transporters in gill MRCs, which supports the notion that gill MRCs play important roles in freshwater Na+ uptake..
43. Ka Fai William Tse, Chris Kong Chu Wong, Nbce1 and H+-atpase mRNA expression are stimulated in the mitochondria-rich cells of freshwater-acclimating Japanese eels (Anguilla japonica), Canadian Journal of Zoology, 10.1139/z11-009, 89, 4, 348-355, 2011.04, Mitochondria-rich cells (MRCs) of fish gills are well known for their roles in Na+ and Cl- excretion in seawater environment. However, the level of understanding of their roles in fresh water is limited. In this study, we used the Percoll gradient technique to isolate gill MRCs from Japanese eels (Anguilla japonica Temminck and Schlegel, 1846) and measured the mRNA expression of two selected ion transporters, which were partially cloned in our laboratory: sodium bicarbonate co-transporter 1 (nbce1) and vacuolar proton pumps (H+-atpase). In addition, protein expressions of H+-ATPase and NBCe1 in whole gill were studied using Western blotting. The data indicated that both NBCe1 and H+-ATPase mRNA and protein expressions increased after seawater to freshwater transfer. This is the first report of changes in mRNA expression for these two ion transporters in MRCs of Japanese eels during seawater to freshwater transfer, confirming the roles of MRCs in osmoregulation in fresh water..
44. Ka Fai William Tse, May Su You, Steven Hao Kee Ho, Yun Jin Jiang, The deubiquitylating enzyme, Cops6, regulates different developmental processes during early zebrafish embryogenesis, International Journal of Developmental Biology, 10.1387/ijdb.103089wt, 55, 1, 19-24, 2011, Zebrafish cops6 encodes a putative deubiquitylating enzyme (DUB) that belongs to the JAMM family. It consists of 297 amino acids and includes the Mov34/MPN/PAD-1 (PF01398) domain. Ubiquitylation is involved in many cellular processes and deconjugation of ubiquitinmodified substrates is important to maintain a sufficient amount of free ubiquitin in the cell. Here, we report our findings regarding the general function of the cops6 gene, as a continuation of our previous studies involving DUB knockdown screening. We have found that cops6 plays different roles in early embryonic development in the zebrafish, including dorsoventral patterning, convergent extension movement and brain formation. In addition, our findings indicate that cops6 plays an anti-apoptotic role during segmentation. Overall, the present study that consolidates our previous work on zebrafish DUB genes, corroborates the hypothesis of multi-functional roles for DUB genes during development..
45. Ka Fai William Tse, Birgit Eisenhaber, Steven H K Ho, Qimei Ng, Frank Eisenhaber, Yun Jin Jiang, Genome-wide loss-of-function analysis of deubiquitylating enzymes for zebrafish development, BMC Genomics, 10.1186/1471-2164-10-637, 10, 2009.12, Background: Deconjugation of ubiquitin and/or ubiquitin-like modified protein substrates is essential to modulate protein-protein interactions and, thus, signaling processes in cells. Although deubiquitylating (deubiquitinating) enzymes (DUBs) play a key role in this process, however, their function and regulation remain insufficiently understood. The "loss-of-function" phenotype studies can provide important information to elucidate the gene function, and zebrafish is an excellent model for this goal.Results: From an in silico genome-wide search, we found more than 90 putative DUBs encoded in the zebrafish genome belonging to six different subclasses. Out of them, 85 from five classical subclasses have been tested with morpholino (MO) knockdown experiments and 57 of them were found to be important in early development of zebrafish. These DUB morphants resulted in a complex and pleiotropic phenotype that, regardless of gene target, always affected the notochord. Based on the huC neuronal marker expression, we grouped them into five sets (groups I to V). Group I DUBs (otud7b, uchl3 and bap1) appear to be involved in the Notch signaling pathway based on the neuronal hyperplasia, while group IV DUBs (otud4, usp5, usp15 and usp25) play a critical role in dorsoventral patterning through the BMP pathway.Conclusion: We have identified an exhaustive list of genes in the zebrafish genome belonging to the five established classes of DUBs. Additionally, we performed the corresponding MO knockdown experiments in zebrafish as well as functional studies for a subset of the predicted DUB genes. The screen results in this work will stimulate functional follow-up studies of potential DUB genes using the zebrafish model system..
46. Ka Fai William Tse, S. C. Chow, C. K C Wong, The cloning of eel osmotic stress transcription factor and the regulation of its expression in primary gill cell culture, Journal of Experimental Biology, 10.1242/jeb.017368, 211, 12, 1964-1968, 2008.06, In the present study, we aimed to clone an osmotic stress transcriptional factor (Ostf) from gill cells of Japanese eels. In addition, we measured its expression in Percoll™-gradient-isolated gill chloride (CC) and pavement (PVC) cells and determined the regulation of its expression in primary gill cell culture. Using degenerative primers and RACE techniques, we cloned a cDNA of 615 bp, encompassing the coding sequence of Ostf (204 amino acids). The cloned Ostf1 DNA sequence shared 84% DNA homology with the Ostf1 of tilapia. In general, the basal Ostf expression level was found to be significantly higher in CCs than in PVCs. In the direct transfer of fish from freshwater to seawater, a significant but transient induction of Ostf mRNA in CCs and PVCs was measured after 6 h of acclimation. Compared with gill CCs, the level of induction measured at PVCs was lower. In the seawater-to-freshwater transfer, no significant change in Ostf transcript levels was detected in either CCs or PVCs. To decipher the regulatory mechanism of Ostf expression, we conducted experiments using primary gill cell culture to specifically address the involvement of two putative osmosensors (i.e. intracellular ion strength/macromolecular crowding and cytoskeleton) in the regulation of Ostf expression. Hypertonic treatment using impermeable solutes (i.e. NaCl, 500 mOsmol l-1) induced Ostf mRNA expression in 6 h, but no noticeable effect was measured using permeable solute (i.e. urea, 500 mOsmol l -1). The induction was transcriptionally regulated and was abolished by the addition of organic osmolytes (i.e. betaine, inositol or taurine) into the culture media. Addition of colchicine (an inhibitor of microtubule polymerization) to hypertonic (with added NaCl, 500 mOsmol l-1) cells reduced Ostf mRNA expression, suggesting that an increase in intracellular ionic strength and the integrity of the cytoskeleton are involved in the activation of Ostf mRNA expression in the cells. Collectively, the results of this study reveal, for the first time, the differential expression of Ostf in isolated CCs and PVCs. The resulting knowledge can shed light on how Ostf participates in hyperosmotic adaptation in fish gills..
47. Ka Fai William Tse, Doris W T Au, Chris K C Wong, Effect of osmotic shrinkage and hormones on the expression of Na +/H+ exchanger-1, Na+/K+/2C1 - cotransporter and Na+/K+-ATPase in gill pavement cells of freshwater adapted Japanese eel, Anguilla japonica, Journal of Experimental Biology, 10.1242/jeb.004101, 210, 12, 2113-2120, 2007.06, It is well-known that gill epithelial cells are important in fish osmoregulation. However, studies on the effect of osmotic stress on the direct cellular responses of the gill epithelial cells are limited. In this paper, we aimed to determine the effects of osmotic hypertonicity, hormones and cellular signaling molecules on the expression of ion transporters in the cultured primary freshwater pavement cells (PVCs), prepared from freshwater-adapted eels (Anguilla japonica). Our data demonstrated that the hypertonic (500 mOsmol l-1) treatment of the isolated PVCs induced cell shrinkage, followed by regulatory volume increase (RVI). Application of blockers (i.e. ouabain, bumetanide and EIPA) demonstrated that Na+/K+-ATPase, Na+/K+/2Cl- cotransporter (NKCC) and Na +/H+ exchanger-1 (NHE-1) were involved in RVI. Western blot analysis of the hypertonic-treated cells revealed a significant induction of NHE-1, NKCC and, a and β subunits of Na+/K +-ATPase. In nonshrunken cultured PVCs, we found that dexamethasone and dibutyryl cAMP treatments significantly stimulated the expression levels of the three ion transporters. Both prolactin and insulin-like growth factor-1, can only induce the expression of NKCC. The effect of thyroid hormone (T 3) and dibutyryl cGMP was negligible. In this study, the induction of ion transporter expression was found to be post-transcriptionally regulated as no significant change in mRNA levels was detected. This observation implies that the regulation is rapid and is probably induced via nongenomic actions..
48. Ka Fai William Tse, Doris W T Au, Chris K C Wong, Characterization of ion channel and transporter mRNA expressions in isolated gill chloride and pavement cells of seawater acclimating eels, Biochemical and Biophysical Research Communications, 10.1016/j.bbrc.2006.06.028, 346, 4, 1181-1190, 2006.08, Ion channels and transporters (i.e. cystic fibrosis transmembrane regulator (CFTR), inward rectifier potassium channel (eKir), Na/K-ATPase, Na/K/Cl2 co-transporter (NKCC), aquaporin-3 (AQP-3), and Na/H exchanger-1 (NHE-1)) are known to be expressed in gill epithelia of teleost fish. Owing to the anatomical complexity of gill structures, their temporal expression profile in seawater acclimating gill pavement (PVCs) and chloride cells (CCs) are limited. In this study, we isolated the gill PVCs and CCs from seawater acclimating Japanese eels to address the issue. In the gill epithelia of freshwater adapted eels, CCs expressed the highest mRNA and/or protein levels of Na/K-ATPase, NKCC, and eKir as demonstrated by real-time PCR and/or immunohistochemical staining. AQP-3 mRNA was highly expressed in freshwater PVCs and its protein was in general expressed in all gill cells. The NHE-1 transcripts were expressed in similar levels in both PVCs and CCs. CFTR mRNA transcript was almost undetectable in all the freshwater gill cell samples. Seawater acclimation induced the transcript and/or protein levels of Na/K-ATPase, NKCC, CFTR, and eKir in CCs. The upregulation and the coexpression of these transporters in CCs suggested their cohort function in mediating Na+, K+, and Cl- transport. The expression of CFTR was found to be tightly regulated as its expression was restricted only in "seawater CCs". AQP-3 transcript and protein levels in PVCs reduced significantly during the acclimation. Interestingly immunocytochemical (ICC) staining of seawater gill epithelia revealed that AQP-3 immunoreactivities were mainly localized in seawater CCs. In the acclimation, there was no significant reduction of NHE-1 mRNA in both PVCs and CCs, however its protein level dropped significantly in the seawater condition. The present study is the first to demonstrate the activation of the mRNA transcripts for the ion channels and transporters in isolated gill CCs during seawater acclimation. The activating mechanism is found to be confined primarily in CCs. These results indicated that in addition to the increase in size and number of CCs, the molecular remodeling and the functional plasticity of CCs were essential in the ion transport process during seawater acclimation..
49. M. S. Yang, Ka Fai William Tse, L. C. Yu, K. M. Li, N. K. Mak, R. C. Gupta, Energy and redox states in the C6 glioma cells following acute exposure to Zn, Se+4, and Se+6 and the correlation with apoptosis, Toxicology Mechanisms and Methods, 10.1080/15376520500194692, 16, 1, 13-19, 2006.01, Changes in cellular energy and redox states in the C6 glioma cells exposed to increasing concentrations of either Zn or Se were studied to examine whether different elements cause different patterns of changes in cellular metabolism. Following a 3-h exposure, both Zn and Se+4 caused dose-dependent decreases in cell viability and total adenosine nucleotides (TAN = ATP + ADP + AMP). In addition, Zn caused a dose-dependent increase in cellular ATP/TAN and a decrease in the ADP/TAN and AMP/TAN. These changes resulted in a significant increase in energy charge potential (ECP = [ATP + 0.5ADP]/TAN). Se+4, on the other hand, caused a dose-dependent decrease in ATP/TAN but an increase in both ADP/TAN and AMP/TAN, resulting in a dose-dependent decrease in ECP. Both Zn and Se+4 caused a dose-dependent decrease in GSH/GSSG and an increase in GSH + GSSG when compared to TAN. In contrast to Zn and Se +4, the nontoxic Se+6 caused no significant changes in cellular energy states but reduced the GSH/GSSG ratio from 3.14 ± 0.49 to 2.05 ± 0.29, which could be explained by the effect of Se on enzymes responsible for GSH metabolism. As the cellular ATP level has been considered an important element that mediates the mode of cell death, it was suggested that a significant increase in ATP/TAN upon exposure to Zn would indicate that cell death occurred via apoptosis, while Se+4 caused a different pattern of cell death. This was confirmed by the appearance of cells with fragmented nucleus in cells treated with Zn, but not Se+4 and Se+6. The results demonstrated that different chemicals caused different patterns of metabolic changes. The correlation between metabolic changes and the mode of cell death was discussed..