Kyushu University Academic Staff Educational and Research Activities Database
List of Reports
Motoko Unoki Last modified date:2019.09.09

Associate Professor / Division of Epigenomics and Development / Department of Molecular and Structural Biology / Medical Institute of Bioregulation

1. Mori T, Ikeda DD, Yamaguchi Y, Unoki M, NIRF Project. , NIRF/UHRF2 occupies a central position in the cell cycle network and allows coupling with the epigenetic landscape. , FEBS Lett., 2012.05, [URL], As predicted by systems biology, a paradigm shift will emerge through the integration of information about different layers of cellular processes. The cell cycle network is at the heart of the cellular computing system, and orchestrates versatile cellular functions. The NIRF/UHRF2 ubiquitin ligase is an “intermodular hub” that occupies a central position in the network, and facilitates coordination among the cell cycle machinery, the ubiquitin-proteasome system, and the epigenetic system. NIRF interacts with cyclins, CDKs, p53, pRB, PCNA, HDAC1, DNMTs, G9a, methylated histone H3 lysine 9, and methylated DNA. NIRF ubiquitinates cyclins D1 and E1, and induces G1 arrest. The NIRF gene is frequently lost in tumors and is a candidate tumor suppressor, while its paralog, the UHRF1 gene, is hardly altered. Thus, investigations of NIRF are essential to understand the entire biological systems. Through integration of the enormous information flows, NIRF may contribute to the coupling between the cell cycle network and the epigenetic landscape. We propose the new paradigm that NIRF produces the extreme diversity in the network wiring that helps the diversity of Waddington’s canals..
2. Unoki M, Kumamoto K, Takenoshita S, Harris CC., Reviewing the current classification of inhibitor of growth family proteins., Cancer Sci., 2009.07, [URL].
3. Unoki M, Kumamoto K, Harris CC., ING proteins as potential anticancer drug targets., Curr Drug Targets., 2009.05, [URL], Recent emerging evidence suggests that ING family proteins play roles in carcinogenesis both as oncogenes and tumor suppressor genes depending on the family members and on cell status. Previous results from non-physiologic overexpression experiments showed that all five family members induce apoptosis or cell cycle arrest, thus it had been thought until very recently that all of the family members function as tumor suppressor genes. Therefore restoration of ING family proteins in cancer cells has been proposed as a treatment for cancers. However, ING2 knockdown experiments showed unexpected results: ING2 knockdown led to senescence in normal human fibroblast cells and suppressed cancer cell growth. ING2 is also overexpressed in colorectal cancer, and promotes cancer cell invasion through an MMP13 dependent pathway. Additionally, it was reported that ING2 has two isoforms, ING2a and ING2b. Although expression of ING2a predominates compared with ING2b, both isoforms confer resistance against cell cycle arrest or apoptosis to cancer cells, thus knockdown of both isoforms is critical to remove this resistance. Taken together, these results suggest that ING2 can function as an oncogene in some specific types of cancer cells, indicating restoration of this gene in cancer cells could cause cancer progression. Because knockdown of ING2 suppresses cancer cell invasion and induces apoptosis or cell cycle arrest, ING2 may be an anticancer drug target. In this brief review, we discuss possible clinical applications of ING2 with the latest knowledge of molecular targeted therapies..
4. Unoki M, Brunet J, Mousli M., Drug discovery targeting epigenetic codes: the great potential of UHRF1, which links DNA methylation and histone modifications, as a drug target in cancers and toxoplasmosis., Biochem Pharmacol., 2009.11, [URL], UHRF1 plays a central role in transferring methylation status from mother cells to daughter cells. Its SRA domain recognizes hemi-methylated DNA that appears in daughter DNA strands during duplication of DNA. UHRF1 recruits DNMT1 to the site and methylates both strands. UHRF1 also binds to HDAC1 and di- and tri-methyl K9 histone H3, ubiquitinates histone H3, and associates with heterochromatin formation, indicating that UHRF1 links histone modifications, DNA methylation, and chromatin structure. UHRF1 is a direct target of E2F1 and promotes G1/S transition. The tumor suppressor p53, which is deficient in 50% of cancers, down-regulates UHRF1 through up-regulation of p21/WAF1 and subsequent deactivation of E2F1. The expression levels of UHRF1 are up-regulated in many cancers, probably partially because of the absence of wild type p53, but it is probably regulated by several other factors. Knockdown of UHRF1 expression in cancer cells suppressed cell growth, suggesting that UHRF1 can be a useful anticancer drug target. Recently, it was revealed that UHRF1 plays important roles not only in carcinogenesis, but also in toxoplasmosis, which is occasionally fatal to people with a weakened immune system, and can cause blindness in the major pathology of ocular toxoplasmosis. Toxoplasma gondii, which causes toxoplasmosis, utilizes UHRF1 to control the cell cycle phase and enhance its proliferation. Thus, knockdown of UHRF1 can be effective at stopping the proliferation of the parasites in infected cells. In this review, we discuss several possible methods that can inhibit the multiple unique functions of UHRF1, which can be utilized for treating cancers and toxoplasmosis..
5. Motoko Unoki, Current and potential anticancer drugs targeting members of the UHRF1 complex including epigenetic modifiers., Recent Pat Anticancer Drug Discov., 2011.01, [URL], Epigenetic modulators play significant roles in carcinogenesis. DNA methylation and histone modifications are the two major epigenetic modifications involved in transcriptional regulation. Many histone modification enzymes and DNMTs are up-regulated in cancer cells, and contribute to malignant transformation. The majority of the current "new generation" of anticancer drugs target abnormally overexpressed oncogenic proteins such as kinases or receptors which mediate oncogenic signal transmission. Overexpression or accumulation of these oncoproteins in cancer is caused directly or indirectly by genetic or epigenetic abnormalities in tumor-associated genes. Among these changes, epigenetic changes in DNA and histones can be caused by aberrant expression of epigenetic modulator proteins in cells. Recently, it has been revealed that UHRF1, which is up-regulated in various cancers, links DNA methylation and histone modifications through binding to hemi-methylated DNA, and also to trimethylated histone H3K9. The UHRF1 complex includes HDAC1, Tip60, G9a, and maintenance and de novo DNMTs. Many of these are reported to be involved in carcinogenesis. Several anticancer drugs targeting epigenetic-machinery such as HDAC inhibitors, and DNMT inhibitors have been developed. Even though these drugs showed some effect on several types of cancer, mild to severe adverse reactions have been observed. In this article, the relevant patents on the strategies to develop safer anticancer drugs targeting epigenetic modulators, focusing on members and modifiers of the UHRF1 complex, are discussed..