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Osteocalcin (OC) is a bone-derived hormone that regulates energy metabolism. OC exists in two forms, carboxylated (GlaOC) and uncaboxylated (GluOC), but only the latter appears to have an endocrine function. In this study, we prepared an extract containing both Gla- and GluOC from boiled pork bone using 0.2 M carbonate buffer at pH 9.5, and tested whether the extract had beneficial effects on improving metabolic parameters in obese mice. The extract equivalent of 1.2 μg of GluOC/mouse was orally administrated to C57BL/6 female mice fed a high-fat, high-sucrose diet. Daily oral administration of the extract for four weeks decreased blood glucose levels and promoted glucose tolerance as well as insulin sensitivity. Our study shows for the first time that boiled pork bones are a source material for osteocalcin in the large-scale production of supplements designed to improve glucose metabolism.

DOI： 10.1080/09168451.2016.1214530

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Uncarboxylated osteocalcin (GluOC), a bone-derived hormone, regulates energy metabolism by stimulating insulin secretion, pancreatic β-cell proliferation, and adiponectin expression in adipocytes. Previously, we showed that long-term intermittent or daily oral administration of GluOC reduced the fasting blood glucose level, improved glucose tolerance, and increased the fasting serum insulin concentration as well as pancreatic β-cell area in female mice fed a normal or high-fat, high-sucrose diet. We have now performed similar experiments with male mice and found that such GluOC administration induced glucose intolerance, insulin resistance, and adipocyte hypertrophy in those fed a high-fat, high-sucrose diet. In addition, GluOC increased the circulating concentration of testosterone and reduced that of adiponectin in such mice. These phenotypes were not observed in male mice fed a high-fat, high-sucrose diet after orchidectomy, but they were apparent in orchidectomized male mice or intact female mice that were fed such a diet and subjected to continuous testosterone supplementation. Our results thus reveal a sex difference in the effects of GluOC on glucose homeostasis. Given that oral administration of GluOC has been considered a potentially safe and convenient option for the treatment or prevention of metabolic disorders, this sex difference will need to be taken into account in further investigations.

DOI： 10.1152/ajpendo.00334.2015

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Uncarboxylated osteocalcin (GluOC), a bone-derived hormone, regulates energy metabolism by stimulating insulin secretion and pancreatic β-cell proliferation. We previously showed that the effect of GluOC on insulin secretion is mediated largely by glucagon-like peptide-1 (GLP-1) secreted from the intestine in response to GluOC exposure. We have now examined the effect of oral administration of GluOC on glucose utilization as well as the fate of such administered GluOC in mice. Long-term intermittent or daily oral administration of GluOC reduced the fasting blood glucose level and improved glucose tolerance in mice without affecting insulin sensitivity. It also increased the fasting serum insulin concentration as well as the β-cell area in the pancreas. A small proportion of orally administered GluOC reached the small intestine and remained there for at least 24. h. GluOC also entered the general circulation, and the serum GLP-1 concentration was increased in association with the presence of GluOC in the intestine and systemic circulation. The putative GluOC receptor, GPRC6A was detected in intestinal cells, and was colocalized with GLP-1 in some of these cells. Our results suggest that orally administered GluOC improved glucose handling likely by acting from both the intestinal lumen and the general circulation, with this effect being mediated in part by stimulation of GLP-1 secretion. Oral administration of GluOC warrants further study as a safe and convenient option for the treatment or prevention of metabolic disorders.

DOI： 10.1016/j.bone.2014.09.006

Language：English  

The uncarboxylated form (ucOC), but not the γ-carboxylated form (GlaOC), of the bone-derived protein osteocalcin stimulates insulin secretion and regulates energy metabolism in insulin target tissues. Glucagon-like peptide-1 (GLP-1) is an insulin secretagogue that is released from the gut in response to food intake. We have now found that Gprc6a, a putative ucOC receptor, is expressed in epithelial cells of the mouse small intestine as well as in STC-1 enteroendocrine cells. Secretion of GLP-1 by STC-1 cells was stimulated by ucOC but not by GlaOC. The serum GLP-1 concentration in mice was increased by intraperitoneal or oral administration of ucOC, whereas GlaOC was effective in this regard only after oral application. Serum insulin levels were also increased by ucOC, and this effect was potentiated by an inhibitor of dipeptidyl peptidase IV and blocked by a GLP-1 receptor antagonist. Intravenous injection of ucOC in mice increased the serum GLP-1 concentration, and also increased the serum level of insulin. Our results suggest that ucOC acts via Gprc6a to induce GLP-1 release from the gut, and that the stimulatory effect of ucOC on insulin secretion is largely mediated by GLP-1.

DOI： 10.1371/journal.pone.0057375

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The subunit composition of GABA_A receptors is known to be associated with distinct physiological and pharmacological properties. Previous studies that used phospholipase C-related inactive protein type 1 knock-out (PRIP-1 KO) mice revealed that PRIP-1 is involved in the assembly and/or the trafficking of γ2 subunit-containing GABA_A receptors. There are two PRIP genes in mammals; thus the roles of PRIP-1 might be compensated partly by those of PRIP-2 in PRIP-1 KO mice. Here we used PRIP-1 and PRIP-2 double knock-out (PRIP-DKO) mice and examined the roles for PRIP in regulating the trafficking of GABA_A receptors. Consistent with previous results, sensitivity to diazepam was reduced in electrophysiological and behavioral analyses of PRIP-DKO mice, suggesting an alteration of γ2 subunit-containing GABA_A receptors. The surface numbers of diazepam binding sites (α/γ2 subunits) assessed by [³H]flumazenil binding were reduced in the PRIP-DKO mice as compared with those of wild-type mice, whereas the cell surface GABA binding sites (α/β subunits, assessed by [³H]muscimol binding) were increased in PRIP-DKO mice. The association between GABA_A receptors and GABA_A receptor-associated protein (GABARAP) was reduced significantly in PRIP-DKO neurons. Disruption of the direct interaction between PRIP and GABA_A receptor β subunits via the use of a peptide corresponding to the PRIP-1 binding site reduced the cell surface expression of γ2 subunit-containing GABA_A receptors in cultured cell lines and neurons. These results suggest that PRIP is implicated in the trafficking of γ2 subunit-containing GABA_A receptors to the cell surface, probably by acting as a bridging molecule between GABARAP and the receptors.

DOI： 10.1523/JNEUROSCI.3155-06.2007

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Adipocyte  

Obesity is characterized by macrophage infiltration into adipose tissue. White adipose tissue remodelling under inflammatory conditions involves both hypertrophy and adipogenesis and is regulated by transcription factors, which are influenced by bone morphogenetic protein (BMP) signalling. MicroRNAs (miRNAs) regulate gene expression and are involved in obesity-related processes such as adipogenesis. Therefore, we identified differentially expressed miRNAs in the epididymal white adipose tissue (eWAT) of mice fed a normal diet (ND) and those fed a high-fat diet (HFD). The expression of miR-6402 was significantly suppressed in the inflamed eWAT of HFD-fed mice than in ND-fed mice. Furthermore, Bmpr2, the receptor for BMP4, was identified as a target gene of miR-6402. Consistently, miR-6402 was downregulated in the inflamed eWAT of HFD-fed mice and in 3T3-L1 cells (preadipocytes) and differentiated 3T3-L1 cells (mature adipocytes) , and BMPR2 expression in these cells was upregulated. Adipogenesis was induced in WAT by BMP4 injection (in vivo) and in 3T3-L1 cells by BMP4 stimulation (in vitro), both of which were inhibited by miR-6402 transfection. Inflamed eWAT showed higher expression of BMPR2 and the adipogenesis markers C/EBPβ and PPARγ, which was suppressed by miR-6402 transfection. Our findings suggest that miR-6402 is a novel anti-adipogenic miRNA that combats obesity by inhibiting the BMP4/BMPR2 signalling pathway and subsequently reducing adipose tissue expansion.

DOI： 10.1080/21623945.2025.2474114

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Alzheimer's disease (AD) is less prevalent in men than in women, although mechanisms remain unclear. Microglia degrade aggregated amyloid β (Aβ) through the lysosomal system, including autophagy. G protein-coupled receptor family C group 6 member A (GPRC6A), predominantly expressed in mouse microglial MG6 cells, is a primary mediator of testosterone signaling. This study examines testosterone's role in modulating Aβ-induced autophagy in microglia. Testosterone promotes Aβ-induced autophagy leading to Aβ clearance in MG6 cells by suppressing extracellular signal-regulated kinase (ERK) phosphorylation and subsequently inhibiting mammalian target of rapamycin (mTOR) activation, which is abrogated by shRNA knockdown of GPRC6A. In in vivo experiments with male 5xFAD AD model mice, Aβ clearance activity is associated with autophagy in microglia and is reduced by orchiectomy, but restored by testosterone supplementation. ERK phosphorylation in the brains of male AD model mice is upregulated by orchiectomy. Therefore, testosterone is involved in autophagy-mediated Aβ clearance in microglia. Aβ accumulation in human brain samples from patients with AD is significantly lower in men than in women, with less pronounced colocalization of Aβ with p62 aggregates, suggesting enhanced autophagic activity in men. In conclusion, testosterone enhances Aβ-induced autophagy in microglia, possibly contributing to lower susceptibility to AD in men.

DOI： 10.1002/advs.202413375

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Periodontitis is a prevalent chronic inflammatory disease requiring the development of drug-based therapies. Epicatechin is a major polyphenol in cocoa extract and possesses numerous pharmacological properties. This study aimed to investigate the suppressive effect of epicatechin on C-C motif chemokine ligand 19 (CCL19)-mediated periodontitis using a mouse model. CCL19 expression was high in mouse gingiva with ligature-induced periodontitis. CCL19 expression was increased by lipopolysaccharide stimulation in murine gingival fibroblasts ESK-1 cells, and CCL19 induced the production of tumor necrosis factor alpha and interleukin-1 beta in mouse macrophage-like RAW264.7 cells. Importantly, lipopolysaccharide-enhanced CCL19 expression in ESK-1 cells was significantly suppressed by pretreatment with epicatechin. In addition, epicatechin administration significantly reduced alveolar bone resorption, and expression of Ccl19 and proinflammatory cytokines in the inflamed gingiva in high-fat diet-fed mice. These results demonstrate that epicatechin protects against periodontitis by reducing CCL19 levels, which may be a promising countermeasure for periodontitis in clinical practice.

DOI： 10.1016/j.jff.2024.106512

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Biochimica et Biophysica Acta - Molecular Basis of Disease  

Postmenopausal women experience bone loss and weight gain. To date, crosstalk between estrogen receptor signals and nuclear factor-κB (NF-κB) has been reported, and estrogen depletion enhances bone resorption by osteoclasts via NF-κB activation. However, it is unclear when and in which tissues NF-κB is activated after menopause, and how NF-κB acts as a common signaling molecule for postmenopausal weight gain and bone loss. Therefore, we examined the role of NF-κB in bone and energy metabolism following menopause. NF-κB reporter mice, which can be used to measure NF-κB activation in vivo, were ovariectomized (OVX) and the luminescence intensity after OVX increased in the metaphyses of the long bones and perigonadal white adipose tissue, but not in the other tissues. OVX was performed on wild-type (WT) and p65 mutant knock-in (S534A) mice, whose mutation enhances the transcriptional activity of NF-κB. Weight gain with worsening glucose tolerance was significant in S534A mice after OVX compared with those of WT mice. The bone density of the sham group in WT or S534A mice did not change, whereas in the S534A-OVX group it significantly decreased due to the suppression of bone formation and increase in bone marrow adipocytes. Disulfiram, an anti-alcoholic drug, suppressed OVX-induced activation of NF-κB in the metaphyses of long bones and white adipose tissue (WAT), as well as weight gain and bone loss. Overall, the activation of NF-κB in the metaphyses of long bones and WAT after OVX regulates post-OVX weight gain and bone loss.

DOI： 10.1016/j.bbadis.2024.167320

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DOI： 10.1016/j.nbd.2024.106605

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Recent findings suggest that uncarboxylated osteocalcin (GluOC) promotes glucose and lipid metabolism via its putative receptor GPRC6A; however, its direct effect on adipocytes remains elusive. In this study, we elucidated the effects of GluOC on adipocytes, with an emphasis on the role of cell adhesion molecules. We determined that GluOC promoted the expression of adipocyte adhesion molecule (ACAM) and its transcription factor Krüppel-like factor 4 and enhanced the cortical actin filament assembly, which ameliorated lipid droplet hypertrophy. Additionally, GluOC upregulated the expression of integrin αVβ3 and activation of focal adhesion kinase (FAK) and prevented insulin receptor substrate 1 (IRS1) degradation by inhibiting the ubiquitin–proteasome system via the FAK–PLC–PKC axis, which activated IRS1–Akt-mediated glucose transporter 4 (GLUT4) transport. Furthermore, we showed that GluOC elevated the expression of the insulin-independent glucose transporters GLUT1 and GLUT8, which facilitated insulin stimulation-independent glucose transport. The GluOC-induced activation of integrin αVβ3 signaling promoted microtubule assembly, which improved glucose and lipid metabolism via its involvement in intracellular vesicular transport. GluOC treatment also suppressed collagen type 1 formation, which might prevent adipose tissue fibrosis in obese individuals. Overall, our results imply that GluOC promotes glucose and lipid metabolism via ACAM, integrin αVβ3, and GLUT1 and 8 expression, directly affecting adipocytes.

DOI： 10.1016/j.bbamcr.2024.119701

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DOI： https://doi.org/10.1016/j.bbamcr.2024.119701

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Alzheimer's disease (AD)—a neurodegenerative disease mainly affecting older patients—is characterized by cognitive deterioration, memory loss, and progressive incapacitation in daily activities. While AD affects almost twice as many females as males, and cognitive deterioration and brain atrophy develop more rapidly in females, the biological causes of these differences remain poorly understood. MicroRNAs (miRNAs) regulate gene expression and impact a wide variety of biological processes; therefore, studying the differential expression of miRNAs in female and male AD patients could contribute to a better understanding of the disease. We reviewed studies of miRNA expression in female and male AD patients and integrated results using a meta-analysis methodology and then identified those genes regulated by the altered miRNAs to establish an association with biological processes. We found 16 (females) and 22 (males) miRNAs altered in the blood of AD patients. Functional enrichment revealed sex-based differences in the affected altered biological processes—protein modification and degradation and cell death in male AD patients and RNA processing in female AD patients. A similar analysis in the brains of AD patients revealed six (females) and four (males) miRNAs with altered expression; however, our analysis failed to highlight any specifically altered biological processes. Overall, we highlight the sex-based differential expression of miRNAs (and biological processes affected) in the blood and brain of AD patients.

DOI： https://doi.org/10.1186/s13293-024-00588-1

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Archives of Biochemistry and Biophysics  

A well-tuned inflammatory response is crucial for an effective immune process. Nuclear factor-kappa B (NF-κB) is a key mediator of inflammatory and innate immunity responses, and its dysregulation is closely associated with immune-related diseases. MicroRNAs (miRNAs) are important inflammation modulators. However, miRNA-regulated mechanisms that implicate NF-κB activity are not fully understood. This study aimed to identify a potential miRNA that could modulate the dysregulated NF-κB signaling during inflammation. We identified miR-582-5p that was significantly downregulated in inflamed murine adipose tissues and RAW264.7 cells. S-phase kinase-associated protein 1 (SKP1), a core component of an E3 ubiquitin ligase that regulates the NF-κB pathway, was proposed as a biological target of miR-582-5p by using TargetScan. The binding of miR-582-5p to a 3'-untranslated region site on Skp1 was confirmed using a dual-luciferase reporter assay; in addition, transfection with a miR-582-5p mimic suppressed SKP1 expression in RAW264.7 cells. Importantly, exogenous miR-582-5p attenuated the production of pro-inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 through suppressing the degradation of the NF-κB inhibitor alpha, followed by the nuclear translocation of NF-κB. Therefore, exogenously applied miR-582-5p can attenuate the NF-κB signaling pathway via targeting Skp1; this provides a prospective therapeutic strategy for treating inflammatory and immune diseases.

DOI： 10.1016/j.abb.2022.109501

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Biochemical and Biophysical Research Communications  

Autophagy is a non-selective action in which cells degrade parts of themselves, reusing degraded cellular components. Among autophagy-related gene (ATG) family members, ATG4 proteins play crucial roles in the microtubule-associated protein 1 light chain 3 (LC3) phosphatidylethanolamine (PE) system which is essential for autophagosome maturation. Although autophagy has been shown to be involved in osteoclastic bone resorption, the role of ATG4/LC3 in bone resorption remains unclear. When mouse bone marrow cells were treated with various concentrations of NSC185058 (NSC), a specific inhibitor of ATG4B, 1 h prior to treatment with receptor activator of NF-κB ligand (RANKL) in the presence of macrophage colony stimulating factor (M-CSF), NSC inhibited osteoclastogenesis in a dose-dependent manner. Addition of NSC in the late stages of osteoclast differentiation suppressed multinucleation and reduced the expression of markers for mature osteoclasts such as Dc-stamp, Mmp9, and Ctsk. NSC also suppressed actin ring formation and pit formation in mature osteoclasts. When a periodontitis model involving eight-week-old male mice in which the right maxillary second molar had been ligated with silk thread was injected with or without NSC, alveolar bone resorption was suppressed by a decrease in the number of osteoclasts in the NSC-treated group. These results suggest that LC3 is important for the maturation of osteoclasts and that LC3 inhibition is a new therapeutic strategy for periodontal disease.

DOI： 10.1016/j.bbrc.2022.09.065

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Insulin signalling is tightly controlled by various factors, but the exact molecular mechanism remains incompletely understood. We have previously reported that phospholipase C-related but catalytically inactive protein (PRIP; used here to refer to both PRIP-1 and PRIP-2, also known as PLCL1 and PLCL2, respectively) interacts with Akt1, the central molecule in insulin signalling. Here, we investigated whether PRIP is involved in the regulation of insulin signalling in adipocytes. We found that insulin signalling, including insulin-stimulated phosphorylation of the insulin receptor (IR), insulin receptor substrate-1 (IRS-1) and Akt, and glucose uptake were impaired in adipocytes from PRIP double-knockout (PRIP-KO) mice compared with those from wild-type (WT) mice. The amount of IR expressed on the cell surface was decreased in PRIP-KO adipocytes. Immunoprecipitation assays showed that PRIP interacted with IR. The reduced cell surface IR in PRIP-KO adipocytes was comparable with that in WT cells when Rab5 (Rab5a, -5b and -5c) expression was silenced using specific siRNA. In contrast, the dephosphorylation of IRS-1 at serine residues, some of which have been reported to be involved in the internalisation of IR, was impaired in cells from PRIP-KO mice. These results suggest that PRIP facilitates insulin signalling by modulating the internalisation of IR in adipocytes.

DOI： 10.1242/jcs.258584

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DOI： 10.1242/jcs.258584

Language：Japanese   Publisher：Japan Society for Developmental Origins of Health and Disease  

DOI： 10.51067/dohad.10.2_42

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DOI： doi: 10.1016/j.molmet.2021.101360.

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Involvement of the bone matrix protein osteocalcin (OC) in the development of learning and memory, and the prevention of anxiety-like behaviors in mice. However, the direct effects of OC on neurons are still unknown comparing to the mechanism how OC affects systemic energy expenditure and glucose homeostasis. In this study, we investigated the effect of OC on proliferation, differentiation, and survival of neurons using the rat pheochromocytoma cell line PC12. RT-PCR analysis for OC receptor candidates revealed that Gpr158, but not Gprc6a, mRNA was expressed in PC12 cells. The growth of PC12 cells cultured in the presence of 5–50 ng/mL of either uncarboxylated (GluOC) or carboxylated (GlaOC) OC was increased compared to cells cultured in the absence of OC. In addition, NGF-induced neurite outgrowth was enhanced by OC, and H O -induced cell death was suppressed by pretreatment with OC. All of these results were observed for both GluOC and GlaOC at comparable levels, suggesting that OC may directly affect cell proliferation, differentiation, and survival by binding to its candidate receptor, GPR158. 2 2

DOI： 10.1016/j.bbrc.2021.03.146

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Cancer is characterized by uncontrolled proliferation resulting from aberrant cell cycle progression. The activation of phosphatidylinositol 3-kinase (PI3K)/AKT signaling, a regulatory pathway for the cell cycle, stabilizes cyclin D1 in the G1 phase by inhibiting the activity of glycogen synthase kinase 3β (GSK3β) via phosphorylation. We previously reported that phospholipase C-related catalytically inactive protein (PRIP), a phosphatidylinositol 4,5-bisphosphate [PI(4,5)P ] binding protein, regulates PI3K/AKT signaling by competitively inhibiting substrate recognition by PI3K. Therefore, in this study, we investigated whether PRIP is involved in cell cycle progression. PRIP silencing in MCF-7 cells, a human breast cancer cell line, demonstrated PI(3,4,5)P signals accumulated at the cell periphery compared to that of the control. This suggests that PRIP reduction enhances PI(3,4,5)P -mediated signaling. Consistently, PRIP silencing in MCF-7 cells exhibited increased phosphorylation of AKT and GSK3β which resulted in cyclin D1 accumulation. In contrast, the exogenous expression of PRIP in MCF-7 cells evidenced stronger downregulation of AKT and GSK3β phosphorylation, reduced accumulation of cyclin D1, and diminished cell proliferation in comparison to control cells. Flow cytometry analysis indicated that MCF-7 cells stably expressing PRIP attenuate cell cycle progression. Importantly, tumor growth of MCF-7 cells stably expressing PRIP was considerably prevented in an in vivo xenograft mouse model. In conclusion, PRIP expression downregulates PI3K/AKT/GSK3β-mediated cell cycle progression and suppresses tumor growth. Therefore, we propose that PRIP is a new therapeutic target for anticancer therapy. 2 3 3

DOI： 10.1016/j.bbrc.2021.03.045

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Bone provides skeletal support and functions as an endocrine organ by producing osteocalcin, whose uncarboxylated form (GluOC) increases the metabolism of glucose and lipid by activating its putative G protein-coupled receptor (family C group 6 subtype A). Low doses (≤10 ng/ml) of GluOC induce the expression of adiponectin, adipose triglyceride lipase and peroxisome proliferator-activated receptor γ, and promote active phosphorylation of lipolytic enzymes such as perilipin and hormone-sensitive lipase via the cAMP-PKA-Src-Rap1-ERK-CREB signaling axis in 3T3-L1 adipocytes. Administration of high-dose (≥20 ng/ml) GluOC induces programmed necrosis (necroptosis) through a juxtacrine mechanism triggered by the binding of Fas ligand, whose expression is induced by forkhead box O1, to Fas that is expressed in adjacent adipocytes. Furthermore, expression of adiponectin and adipose triglyceride lipase in adipocytes is triggered in the same manner as following low-dose GluOC stimulation; these effects protect mice from diet-induced accumulation of triglycerides in hepatocytes and consequent liver injury through the upregulation of nuclear translocation of nuclear factor-E2-related factor-2, expression of antioxidant enzymes, and inhibition of the c-Jun N-terminal kinase pathway. Evaluation of these molecular mechanisms leads us to consider that GluOC might have potential as a treatment for lipid metabolism disorders. Indeed, there have been many reports demonstrating the negative correlation between serum osteocalcin levels and obesity or non-alcoholic fatty liver disease, a common risk factor for which is dyslipidemia in humans. The present review summarizes the effects of GluOC on lipid metabolism as well as its possible therapeutic application for metabolic diseases including obesity and dyslipidemia.

DOI： 10.1016/j.jbior.2020.100752

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DOI： 10.1002/cbf.3476

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Peripheral lipopolysaccharide (LPS) injection induces systemic inflammation through the activation of the inhibitor of nuclear factor kappa B (NF-κB) kinase (IKK)/NF-κB signaling pathway, which promotes brain dysfunction resulting in conditions including anorexia. LPS-mediated reduction of food intake is associated with activation of NF-κB signaling and phosphorylation of the transcription factor signal transducer and activator of transcription 3 (STAT3) in the hypothalamus. We recently reported phospholipase C-related catalytically inactive protein (PRIP) as a new negative regulator of phosphatidylinositol 3-kinase/AKT signaling. AKT regulates the IKK/NF-κB signaling pathway; therefore, this study aimed to investigate the role of PRIP/AKT signaling in LPS-mediated neuroinflammation-induced anorexia. PRIP gene (Prip1 and Prip2) knockout (Prip-KO) mice intraperitoneally (ip) administered with LPS exhibited increased anorexia responses compared with wild-type (WT) controls. Although few differences were observed between WT and Prip-KO mice in LPS-elicited plasma pro-inflammatory cytokine elevation, hypothalamic pro-inflammatory cytokines were significantly upregulated in Prip-KO rather than WT mice. Hypothalamic AKT and IKK phosphorylation and IκB degradation were significantly increased in Prip-KO rather than WT mice, indicating further promotion of AKT-mediated NF-κB signaling. Consistently, hypothalamic STAT3 was further phosphorylated in Prip-KO rather than WT mice. Furthermore, suppressor of cytokine signaling 3 (Socs3), a negative feedback regulator for STAT3 signaling, and cyclooxogenase-2 (Cox2), a candidate molecule in LPS-induced anorexigenic responses, were upregulated in the hypothalamus in Prip-KO rather than WT mice. Pro-inflammatory cytokines were upregulated in hypothalamic microglia isolated from Prip-KO rather than WT mice. Together, these findings indicate that PRIP negatively regulates LPS-induced anorexia caused by pro-inflammatory cytokine expression in the hypothalamus, which is mediated by AKT-activated NF-κB signaling. Importantly, hypothalamic microglia participate in this PRIP-mediated process. Elucidation of PRIP-mediated neuroinflammatory responses may provide novel insights into the pathophysiology of many brain dysfunctions.

DOI： 10.1016/j.neuint.2019.104563

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The uncarboxylated form of osteocalcin (GluOC) regulates glucose and lipid metabolism in mice. We previously showed that low-dose (≤10 ng/ml) GluOC induces the expression of adiponectin and peroxisome proliferator-activated receptor γ (PPARγ) via a cAMP–PKA–ERK–CREB signaling pathway in 3T3-L1 adipocytes. We also noticed that high-dose (≥20 ng/ml) GluOC inhibits the expression of adiponectin and PPARγ in these cells. We have here explored the mechanism underlying these effects of high-dose GluOC. High-dose GluOC triggered morphological changes in 3T3-L1 adipocytes suggestive of the induction of cell death. It activated the putative GluOC receptor GPRC6A and thereby induced the production of cAMP and activation of protein kinase A (PKA), similar to signaling by low-dose GluOC with the exception that the catalytic subunit of PKA also entered the nucleus. Cytosolic PKA induced phosphorylation of cAMP response element-binding protein (CREB) at serine-133 via extracellular signal-regulated kinase (ERK). Nuclear PKA appeared to mediate the inhibitory phosphorylation of salt-inducible kinase 2 (SIK2) at serine-358 and thereby to alleviate the inhibitory phosphorylation of the CREB co-activator p300 at serine-89. The activation of CREB and p300 resulted in increased expression of the transcription factor FoxO1 and consequent upregulation of Fas ligand (FasL) at the plasma membrane. The interaction of FasL with Fas on neighboring adipocytes triggered the phosphorylation at threonine-357/serine-358 and homotrimerization of mixed-lineage kinase domain-like protein (MLKL), a key regulator of necroptosis, as well as Ca
²⁺
influx via transient receptor potential melastatin 7 (TRPM7), the generation of reactive oxygen species and lipid peroxides, and dephosphorylation of dynamin-related protein 1 (DRP1) at serine-637, resulting in mitochondrial fragmentation. Together, our results indicate that high-dose GluOC triggers necroptosis through upregulation of FasL at the plasma membrane in a manner dependent of activation of CREB-p300, followed by the activation of Fas signaling in neighboring adipocytes.

DOI： 10.1038/s41419-018-1257-7

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Objectives We have previously demonstrated that phospholipase C-related catalytically inactive protein (PRIP) is involved in fat metabolism and energy consumption. However, whether PRIP participates in body energy metabolism in vivo remains to be determined. Therefore, we examined whether PRIP deficiency affects whole-body energy homeostasis, which is modulated by non-shivering thermogenesis in brown adipose tissue, using a cold exposure animal model. Methods Fasting plasma triacylglycerol levels were measured to evaluate fat metabolism in wild-type and Prip-KO mice. In addition, a glucose tolerance test (GTT) and insulin tolerance test (ITT) were performed. To determine changes in energy consumption, mice were exposed to a cold environment for 7 days, and expression of uncoupling protein 1 (UCP1) in brown adipose tissue was analyzed via western blotting. Results Fasting plasma levels of triacylglycerols were significantly higher in Prip-KO mice than in wild-type mice. However, Prip-KO mice showed a healthy phenotype based on GTT and ITT. UCP1 expression was significantly upregulated in the brown and white adipose tissues of Prip-KO mice exposed to cold conditions. Conclusion Prip-KO mice exhibit greater ability to consume lipids as an energy source, indicating that PRIP modulates of systemic energy expenditure. Our findings provide increased understanding of PRIP-mediated non-shivering thermogenic mechanisms and offers important insights for the treatment and control of obesity.

DOI： 10.1016/j.job.2017.04.001

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Because of the poor response to chemotherapy and radiation therapy, new treatment approaches by immune-based therapy involving activated T cells are required for melanoma. We previously reported that the uncarboxylated form of osteocalcin (GluOC), derived from osteoblasts, potentially suppresses human prostate cancer cell proliferation by direct suppression of cell growth. However, the mechanisms in vivo have not been elucidated. In this study, we found that GluOC suppressed tumor growth of B16 mouse melanoma transplants in C57Bl/6N wild-type mice. Our data demonstrated that GluOC suppressed cell growth by downregulating phosphorylation levels of receptor tyrosine kinases and inducing apoptosis in vitro. Additionally, stimulation of primary mouse splenocytes with concanavalin A, a polyclonal T-cell mitogen, in the presence of GluOC increased T cell proliferation and their interferon-γ production. Taken together, we demonstrate that GluOC exerts multiple antitumor effects not only in vitro, but also in vivo through cellular immunostimulatory effects against B16 mouse melanoma cells.

DOI： 10.7150/jca.18648

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The final step of regulated exocytosis, membrane fusion, is mediated by formation of the SNARE complex by syntaxin, SNAP-25 (synaptosomal-associated protein of 25 kDa), and VAMP (vesicle-associated membrane protein). Phosphorylation of SNARE and accessory proteins contributes to regulation of exocytosis. We previously identified residues of SNAP-25 phosphorylated by protein kinase A (PKA) and PKC. However, the physiological role of SNAP-25 phosphorylation in exocytosis, in particular with regard to SNARE complex formation, has remained elusive. SNARE complex formation by purified recombinant SNAP-25, syntaxin-1, and VAMP-in vitro was inhibited or promoted as a result of the phosphorylation at Thr¹³⁸ by PKA or at Ser¹⁸⁷ by PKC, respectively. SNARE complex formation in intact PC12 cells was similarly inhibited by forskolin (activator of PKA) and promoted by phorbol 12-myristate 13-acetate (PMA, activator of PKC). Noradrenaline secretion from PC12 cells induced by a high K⁺ concentration was enhanced by forskolin or PMA. Stable depletion of SNAP-25 inhibited high-K⁺-induced noradrenaline secretion. Forced expression of WT SNAP-25 restored the secretory response of the SNAP-25-depleted cells to high-K⁺, and this response was enhanced by forskolin or PMA. Expression of the nonphosphorylatable T138A or S187A mutants of SNAP-25 similarly rescued the secretory response to high-K⁺, but the augmentation of this response by forskolin was more pronounced in the cells expressing SNAP-25 (T138A) than in those expressing SNAP-25 (WT), whereas that by PMA was less pronounced in those expressing SNAP-25 (S187A). Our results thus suggest that SNAP-25 phosphorylation by PKA or PKC contributes differentially to the control of exocytosis in PC12 cells by regulating SNARE complex formation.

DOI： 10.1016/j.cellsig.2015.12.014

Language：English  

Objective Maternal diet during pregnancy has been found to influence the health of offspring. However, strategies for modulation of maternal energy metabolism without an adverse effect on the fetus have remained limited. It was recently shown that oral administration of uncarboxylated osteocalcin (GluOC) improves metabolic status in adult female mice. Whether maternal GluOC administration during gestation might improve the metabolic status of offspring was investigated. Methods Female C57BL/6 mice were fed a normal diet (ND) or high-fat, high-sucrose diet (HFS) and were given saline or GluOC by oral administration during pregnancy. The resulting offspring were in turn assigned to ND- or HFS-fed groups immediately after weaning, and their body weight, glucose metabolism, serum lipid parameters, and level of adipose tissue inflammation were subsequently assessed. Results Maternal HFS feeding during gestation had adverse effects on glucose and lipid parameters, body weight, and adipose tissue inflammation in female offspring fed the same diet, and these effects were attenuated by maternal oral GluOC administration. Conclusions Maternal oral administration of GluOC protects HFS-fed female offspring from metabolic disorders induced by maternal obesity.

DOI： 10.1002/oby.21447

Language：English  

Serum levels of osteocalcin (OC), a bone matrix non-collagenous protein secreted by osteoblasts, are correlated with pathological bone remodeling such as the bone metastasis of cancer, as well as physiological bone turnover. The pathological roles in prostate cancer growth of the two existing types of serum OC, γ-carboxylated (GlaOC) and lower- (or un-) carboxylated (GluOC), have not yet been discriminatively examined. In the present study, we demonstrate that normal prostate epithelial cell growth was promoted by both types of OC, while growth of cancer cells in the prostate was accelerated by GlaOC but suppressed by GluOC. We suggest that OC regulates prostate cancer growth depending on the γ-carboxylation, in part by triggering reduced phosphorylation of receptor tyrosine kinases.

DOI： 10.7150/jca.15523

Language：English  

A close relationship between the bone and systemic glucose metabolism has recently been the center of attention, since the uncarboxylated form of osteocalcin (GluOC), a bone-derived protein, but not the γ-carboxylated form, is involved in glucose metabolism. However, the analysis of GluOC effect using isolated organs and related cell lines are required to understand its roles in a whole systemic metabolic status. In the present study, we examined the effect of GluOC on cell lines derived from skeletal muscle to explore the mechanisms by which GluOC regulates glucose uptake. In the differentiated C2C12 myotubes, GluOC dose-dependently induced the phosphorylation of ERK without affecting intracellular cAMP and Ca²⁺ levels. This effect was inhibited by U0126, an inhibitor of ERK kinase (MEK). Additionally, U73122, an inhibitor of phospholipase C tended to inhibit it as well. Furthermore, cell treatment with GluOC for a long period promoted insulin-induced Akt phosphorylation and glucose uptake in the myotubes, which was abolished by ERK signaling inhibition. These results indicate that GluOC does not triggered Akt phosphorylation and glucose uptake by itself but promotes insulin-induced glucose uptake in myotubes, probably by up-regulating Akt signaling through ERK activation.

DOI： 10.1016/j.bbrc.2015.02.123

Language：English  

In addition to providing skeletal support, the bone is an endocrine organ that produces osteocalcin, whose uncarboxylated form (GluOC) increases insulin secretion either directly or indirectly by promoting incretin secretion. We have now investigated the signaling pathway by which GluOC increases expression of adiponectin in adipocytes. Activation of its putative receptor GPRC6A by GluOC induced the intracellular accumulation of cAMP and consequent activation of protein kinase A (PKA) in differentiated 3T3-L1 adipocytes. It also induced phosphorylation of CREB (cAMP response element binding protein), but this effect appeared to be mediated indirectly by extracellular signal-regulated kinase (ERK) rather than directly by PKA, given that it was attenuated by the ERK signaling inhibitor U0126. Activated PKA also induced activation of the tyrosine kinase Src, the small GTPase Rap1, an upstream of ERK and CREB phosphorylation. Activated CREB up-regulated the expression of peroxisome proliferator-activated receptor γ (PPARγ), which in turn led to induction of adiponectin expression. Finally, intermittent oral administration of GluOC in mice reduced the size of gonadal white adipocytes as well as increased the expression of PPARγ and adiponectin in these cells. Our results have thus revealed the signaling pathway by which GluOC induces adiponectin expression in adipocytes.

DOI： 10.1016/j.cellsig.2014.12.018

Language：English  

Phosphorylation of hormone-sensitive lipase (HSL) and perilipin by protein kinase A (PKA) promotes the hydrolysis of lipids in adipocytes. Although activation of lipolysis by PKA has been well studied, inactivation via protein phosphatases is poorly understood. Here, we investigated whether phospholipase C-related catalytically inactive protein (PRIP), a binding partner for protein phosphatase 1 and protein phosphatase 2A (PP2A), is involved in lipolysis by regulating phosphatase activity. PRIP knockout (PRIP-KO) mice displayed reduced body-fat mass as compared with wild-type mice fed with standard chow ad libitum. Most other organs appeared normal, suggesting that mutant mice had aberrant fat metabolism in adipocytes. HSL in PRIP-KO adipose tissue was highly phosphorylated compared to that in wild-type mice. Starvation of wild-type mice or stimulation of adipose tissue explants with the catabolic hormone, adrenaline, translocated both PRIP and PP2A from the cytosol to lipid droplets, but the translocation of PP2A was significantly reduced in PRIP-KO adipocytes. Consistently, the phosphatase activity associated with lipid droplet fraction in PRIP -KO adipocytes was significantly reduced and was independent of adrenaline stimulation. Lipolysis activity, as assessed by measurement of non-esterified fatty acids and glycerol, was higher in PRIP-KO adipocytes. When wild-type adipocytes were treated with a phosphatase inhibitor, they showed a high lipolysis activity at the similar level to PRIP-KO adipocytes. Collectively, these results suggest that PRIP promotes the translocation of phosphatases to lipid droplets to trigger the dephosphorylation of HSL and perilipin A, thus reducing PKA-mediated lipolysis. Copyright:

DOI： 10.1371/journal.pone.0100559

Language：English  

Upon starvation, cells undergo autophagy, an intracellular bulk-degradation process, to provide the required nutrients. Here, we observed that phospholipase C-related catalytically inactive protein (PRIP) binds to microtubule-associated protein 1 light chain 3 (LC3), a mammalian autophagy-related initiator that regulates the autophagy pathway. Then, we examined the involvement of PRIP in the nutrient depletion-induced autophagy pathway. Enhanced colocalization of PRIP with LC3 was clearly seen in nutrient-starved mouse embryonic fibroblasts under a fluorescent microscope, and interaction of the proteins was revealed by immunoprecipitation experiments with an anti-LC3 antibody. Under starvation conditions, there were more green fluorescent protein fused-LC3 dots in mouse embryonic fibroblasts from PRIP-deficient mice than in fibroblasts from wild type cells. The formation of new dots in a single cell increased, as assessed by time-lapse microscopy. Furthermore, the increase in autophagosome formation in PRIP-deficient cells was notably inhibited by exogenously overexpressed PRIP. Taken together, PRIP is a novel LC3-binding protein that acts as a negative modulator of autophagosome formation.

DOI： 10.1016/j.bbrc.2013.01.119

Language：English  

PRIP (phospholipase C-related, but catalytically inactive protein) is a novel protein isolated in this laboratory. PRIP-deficient mice showed increased serum gonadotropins, but decreased gonadal steroid hormones. This imbalance was similar to that for the cause of bone disease, such as osteoporosis. In the present study, therefore, we analyzed mutant mice with special reference to the bone property. We first performed three-dimensional analysis of the femur of female mice. The bone mineral density and trabecular bone volume were higher in mutant mice. We further performed histomorphometrical assay of bone formation parameters: bone formation rate, mineral apposition rate, osteoid thickness, and osteoblast number were up-regulated in the mutant, indicating that increased bone mass is caused by the enhancement of bone formation ability. We then cultured primary cells isolated from calvaria prepared from both genotypes. In mutant mice, osteoblast differentiation, as assessed by alkaline phosphatase activity and the expression of osteoblast differentiation marker genes, was enhanced. Moreover, we analyzed the phosphorylation of Smad1/5/8 in response to bone morphogenetic protein, with longer phosphorylation in the mutant. These results indicate that PRIP is implicated in the negative regulation of bone formation.

DOI： 10.1074/jbc.M111.235903

Language：English  

The GABA_A receptor, a pentamer composed predominantly of α, β, and γ subunits, mediates fast inhibitory synaptic transmission. We have previously reported that phospholipase C-related inactive protein (PRIP) is a modulator of GABA_A receptor trafficking and that knockout (KO) mice exhibit a diazepam-insensitive phenotype in the hippocampus. The α subunit affects diazepam sensitivity; α1, 2, 3, and 5 subunits assemble with any form of β and the γ2 subunits to produce diazepam-sensitive receptors, whereas α4 or α6/β/γ2 receptors are diazepam-insensitive. Here, we investigated how PRIP is implicated in the diazepam-insensitive phenotype using cerebellar granule cells in animals expressing predominantly the α6 subunit. The expression of α1/β/γ2 diazepam-sensitive receptors was decreased in the PRIP-1 and 2 double KO cerebellum without any change in the total number of benzodiazepine-binding sites as assessed by radioligand-binding assay. Since levels of the α6 subunit were increased, the α1/β/γ2 receptors might be replaced with α6 subunit-containing receptors. Then, we further performed autoradiographic and electrophysiologic analyses. These results suggest that the expression of α6/δ receptors was decreased in cerebellar granule neurons, while that of α6/γ2 receptors was increased. PRIP-1 and 2 double KO mice exhibit a diazepam-insensitive phenotype because of a decrease in diazepam-sensitive (α1/γ2) and increase in diazepam-insensitive (α6/γ2) GABA_A receptors in the cerebellar granule cells.

DOI： 10.1111/j.1471-4159.2010.06754.x

Language：English  

GABA_A receptors are heteropentameric ligand-gated chloride channels composed of a variety of subunits, including α1 - 6, β1 - 3, γ1 - 3, δ, ε, θ, and π, and play a key role in controlling inhibitory neuronal activity. Modification of the efficacy of the synaptic strength is produced by changes in both the number of neuronal surface receptors and pentameric molecular assembly, leading to differences of sensitivity to neurotransmitters and neuromimetic drugs. Therefore, it is important to understand the molecular mechanisms regulating the so-called "life cycle of GABA_A receptors" including sequential pentameric assembly at the site synthesized, intracellular transport through the Golgi apparatus and the cytoplasm, insertion into the cell membrane, functional modulation at the cell surface, and finally internalization, followed by either recycling back to the surface membrane or lysosomal degradation. This review is focused on events related to the surface expression of the receptor containing the γ2 subunit and clathrin /AP2 complex-mediated phospho-regulated endocytosis of the receptor, with special reference to the function of novel GABA_A receptor modulators, GABARAP (GABA_A receptor-associated protein) and PRIP (phospholipase C-related, but catalytically inactive protein).

DOI： 10.1254/jphs.CP0070063

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A mechanism for regulating the strength of synaptic inhibition is enabled by altering the number of GABA_A receptors available at the cell surface. Clathrin and adaptor protein 2 (AP2) complex-mediated endocytosis is known to play a fundamental role in regulating cell surface GABA_A receptor numbers. Very recently, we have elucidated that phospholipase C-related catalytically inactive protein (PRIP) molecules are involved in the phosphorylation-dependent regulation of the internalization of GABA_A receptors through association with receptor β subunits and protein phosphatases. In this study, we examined the implications of PRIP molecules in clathrin-mediated constitutive GABA_A receptor endocytosis, independent of phospho-regulation. We performed a constitutive receptor internalization assay using human embryonic kidney 293 (HEK293) cells transiently expressed with GABA_A receptor α/β/γ subunits and PRIP. PRIP was internalized together with GABA_A receptors, and the process was inhibited by PRIP-binding peptide which blocks PRIP binding to β subunits. The clathrin heavy chain, μ2 and β2 subunits of AP2 and PRIP-1, were complexed with GABA_A receptor in brain extract as analyzed by co-immunoprecipitation assay using anti-PRIP-1 and anti-β2/3 GABA_A receptor antibody or by pull-down assay using β subunits of GABA_A receptor. These results indicate that PRIP is primarily implicated in the constitutive internalization of GABA_A receptor that requires clathrin and AP2 protein complex.

DOI： 10.1111/j.1471-4159.2006.04399.x

Language：English  

The investigation of chemically synthesized inositol 1,4,5-trisphosphate [Ins(1,4,5)P₃] analogs has led to the isolation of a novel protein with a molecular size of 130 kDa, characterized as a molecule with a domain organization similar to phospholipase C (PLC)-δ1 but lacking enzymatic activity. Two isoforms of the molecule were subsequently identified, the molecule has been named PRIP (PLC-related, but catalytically inactive protein), with the two isoforms named PRIP-1 and-2. Regarding its ability to bind Ins (1,4,5)-P₃ via the pleckstrin homology domain, the involvement of PRIP-1 in Ins(1,4,5)P₃-mediated Ca²⁺ signaling was first examined. Yeast two-hybrid screening of a brain cDNA library identified GABARAP (GABA_A receptor-associated protein) and PP1 (protein phosphatase 1), which led us to examine the possible neurological involvement of PRIP, particularly in GABA_A receptor signaling. PRIP-1 and-2 double knock-out (DKO) mice were analyzed for GABA_A receptor function with special reference to the action of benzodiazepines whose target is the γ subunit of the receptors; sensitivity to benzodiazepine was reduced, as assessed by biochemical, electrophysiological, and behavioral analyses of DKO mice, suggesting the dysfunction of γ2 subunit-containing GABA_A receptors. The mesencephalic trigeminal nucleus, which mediates perceptions from periodontal mechanoreceptors and jaw-closer muscle spindles, receives many synaptic inputs, including those from GABA_A receptors, indicating that PRIP might indirectly be involved in rhythmical jaw movement. In the present article, we summarize our current research and the functional significance of PRIP.

DOI： 10.2330/joralbiosci.49.244

Language：English  

GABA_A receptors are a family of ligand-gated ion channels that are pentamer composed pre-dominantly of α, β and γ subunits. They are the major target of the endogenous inhibitory neurotransmitter (GABA, γ-aminobutyric acid) and maintain the majority of fast inhibitory ion currents in the central nervous system, in addition to being drug targets for benzodiazepines, barbiturates, alcohols, neurosteroids, and some anesthetics. Moreover, modifications in GABA_A receptor function are crucial in central nervous system diseases such as anxiety disorders, sleep disturbances, and seizure disorders. Therefore it is very important to understand the molecular mechanisms underlying the maintenance of functional inhibitory synapses including GABA_A receptors. We have first isolated PRIP (phospholipase C-related, but catalytically inactive protein) as a novel inositol 1,4,5-trisphosphate binding protein, and subsequently found GABARAP (GABA_A receptor associated protein) as one of binding partners that binds to γ2 subunit of the receptor and thus is implicated in the clustering and trafficking of the receptor to synaptic membrane. Further studies revealed that PRIP binds β subunit of the receptors and PP1c (catalytic subunit of protein phosphatase 1). These findings have prompted us to explore the possible involvement of PRIP in modulation of GABA_A receptor signaling. Here we summarize our current understanding regarding how PRIP is involved in the modification of GABA_A receptor signaling on the basis of the characteristics of these interacting molecules.

DOI： 10.2330/joralbiosci.49.105

Event date： 2023.12

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Event date： 2021.10

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Venue：Web開催   Country：Japan  

GPRC6A, a member of family C of G protein-coupled receptors, has been proposed to be a master regulator of metabolic processes. It has been reported that global deletion of GPRC6A increases susceptibility to develop diet-induced obesity and metabolic related disorders. However, due to its broad tissue distribution and its ability to respond to a variety of hormonal and nutritional signals, the underlying cellular and molecular mechanisms of the metabolic disorders are still unclear. We previously reported that long-term oral administration of osteocalcin, one of the GPRC6A ligands, markedly reduced adipocyte size and improved glucose tolerance in wild type mice. Thus, we generated adipocyte-specific GPRC6A knockout mice (adG6AKO) and found that these animals manifested increased adipose tissue weight, adipocyte hypertrophy, and adipose tissue inflammation under obesogenic environment. These effects were associated with reduced lipolytic activity due to down-regulation of lipolytic enzymes in adipose tissue of adG6AKO mice. Our results suggest that the constitutive activation of GPRC6A signaling in adipocytes plays a key role in adipose lipid handling and the prevention of obesity and related metabolic disorders.

Event date： 2021.10

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Venue：Web開催   Country：Japan  

Event date： 2020.10

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Venue：Online   Country：Japan  

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Venue：Online   Country：Japan  

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Venue：Online   Country：Japan  

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Venue：Online   Country：Japan  

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Venue：Merbourne   Country：Australia  

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Venue：東京都千代田区   Country：Japan  

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Venue：Seoul   Country：Korea, Republic of  

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Venue：福岡市   Country：Japan  

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Venue：長野県松本市   Country：Japan  

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Venue：Seoul   Country：Korea, Republic of  

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Venue：Ewha Womans University, Seoul   Country：Korea, Republic of  

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Venue：Ewha Womans University, Seoul   Country：Korea, Republic of  

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Venue：Ewha Womans University, Seoul   Country：Korea, Republic of  

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Venue：Ewha Womans University, Seoul   Country：Korea, Republic of  

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Venue：Kyushu University, Fukuoka   Country：Japan  

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Venue：Bangkok   Country：Thailand  

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Venue：名古屋   Country：Japan  

Oral administration of osteocalcin improves glucose utilization by stimulating glucgon-like peptide-1 secretion

Event date： 2014.10

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Venue：福岡市   Country：Japan  

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Venue：Bologna   Country：Italy  

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Venue：仙台市   Country：Japan  

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Venue：岡山県岡山市   Country：Japan  

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Venue：Galveston, TX, USA   Country：Japan  

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Venue：福岡市   Country：Japan  

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Language：Japanese   Publisher：FoodSTYLE21  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publisher：(有)科学評論社  

Language：Japanese   Publisher：糖尿病・内分泌代謝科  

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Bone provides skeletal support and functions as an endocrine organ by producing osteocalcin, whose uncarboxylated form (GluOC) increases the metabolism of glucose and lipid by activating its putative G protein-coupled receptor (family C group 6 subtype A). Low doses (≤10 ng/ml) of GluOC induce the expression of adiponectin, adipose triglyceride lipase and peroxisome proliferator-activated receptor γ, and promote active phosphorylation of lipolytic enzymes such as perilipin and hormone-sensitive lipase via the cAMP-PKA-Src-Rap1-ERK-CREB signaling axis in 3T3-L1 adipocytes. Administration of high-dose (≥20 ng/ml) GluOC induces programmed necrosis (necroptosis) through a juxtacrine mechanism triggered by the binding of Fas ligand, whose expression is induced by forkhead box O1, to Fas that is expressed in adjacent adipocytes. Furthermore, expression of adiponectin and adipose triglyceride lipase in adipocytes is triggered in the same manner as following low-dose GluOC stimulation; these effects protect mice from diet-induced accumulation of triglycerides in hepatocytes and consequent liver injury through the upregulation of nuclear translocation of nuclear factor-E2-related factor-2, expression of antioxidant enzymes, and inhibition of the c-Jun N-terminal kinase pathway. Evaluation of these molecular mechanisms leads us to consider that GluOC might have potential as a treatment for lipid metabolism disorders. Indeed, there have been many reports demonstrating the negative correlation between serum osteocalcin levels and obesity or non-alcoholic fatty liver disease, a common risk factor for which is dyslipidemia in humans. The present review summarizes the effects of GluOC on lipid metabolism as well as its possible therapeutic application for metabolic diseases including obesity and dyslipidemia.

DOI： 10.1016/j.jbior.2020.100752

Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Background: Overweight and obesity are defined as excessive or abnormal fat accumulation in adipose tissues, and increase the risk of morbidity in many diseases, including hypertension, dyslipidemia, type 2 diabetes, coronary heart disease, and stroke, through pathophysiological mechanisms. There is strong evidence that weight loss reduces the risk of metabolic syndrome by limiting blood pressure and improving the levels of serum triglycerides, total cholesterol, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol. To date, several attempts have been made to develop effective anti-obesity medication or weight-loss drugs; however, satisfactory drugs for clinical use have not yet been developed. Therefore, elucidation of the molecular mechanisms driving fat metabolism (adipogenesis and lipolysis) represents the first step in developing clinically useful drugs and/or therapeutic treatments to control obesity. Highlight: In our previous study on intracellular signaling of phospholipase C-related catalytically inactive protein (PRIP), we generated and analyzed Prip-double knockout (Prip-DKO) mice. Prip-DKO mice showed tolerance against insulin resistance and a lean phenotype with low fat mass. Here, we therefore reviewed the involvement of PRIP in fat metabolism and energy expenditure. We conclude that PRIP, a protein phosphatase-binding protein, can modulate fat metabolism via phosphoregulation of adipose lipolysis-related molecules, and regulates non-shivering heat generation in brown adipocytes. Conclusion: We propose PRIP as a new therapeutic target for controlling obesity or developing novel anti-obesity drugs.

DOI： 10.1016/j.job.2019.04.002

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：150

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：6

Type：Competition, symposium, etc. 

Number of participants：50

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Type：Competition, symposium, etc. 

Number of participants：50

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：2

Type：Competition, symposium, etc. 

Number of participants：100

Type：Research consultation

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科学の常識、女性が再定義 医療やAI革新生む
国際女性デーに際し、医学研究分野におけるジェンダード・イノベーションについて、オステオカルシンの代謝改善効果が雌雄で異なることを発見した経緯と現在行なっているアルツハイマー型認知症における性差に関する研究について概説した。また、近年の医学分野の研究において、動物実験における性別考慮の重要性や、研究者のジェンダーが及ぼすインパクトについて概説した。

クインテッセンス出版によるダイアリーに、ジェンダード・イノベーションにまつわるコラムを執筆した。

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"「口腔から考える健康戦略」の確立と普及に向けて"と題して、口腔機能分子科学分野の兼松隆教授、クラウンブリッジ補綴学分野の荻野洋一郎准教授と対談した。そこで、「ジェンダード・イノベーション」性差を考慮することで新たなイノベーションを創出しよう、という考え方を紹介し、歯科診療の現場においてもより効果的で個別性の高い治療・予防計画を立てられる可能性について議論した。

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ジェンダード・イノベーション〜性差観点の抜け漏れは人命にも影響〜
ジェンダードイノベーションの医学分野の事例として、骨由来ホルモン、オステオカルシンの作用が雌雄で異なることを明らかにした研究成果について掲載された。

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インスリン分泌を促して血糖値の調節ならびに糖・脂質代謝の制御に重要な役割を果たしていることが報告され、注目されるようになった骨ホルモン「オステオカルシン」。糖尿病治療などの創薬に期待が高まっているが、骨の健康に関わる栄養指導にも影響を及ぼすのだろうか？糖・エネルギー代謝の視点で研究に取り組む専門家としてその動向を解説した。

研究開発の現場では、動物実験を行う際にオスのみを使って実験を行うことが多い。しかし、単に体格の差だけでなく、体内での機能における男女差が薬の効きの違いや疾患の感受性の違いを生む可能性があることが明らかにされつつある。
我々は、骨基質タンパク質であるオステオカルシンを長期間経口投与すると全身の代謝が活性化することをマウスの実験で明らかにしたが、オス・メス両性のマウスを用いて実験した結果、代謝改善効果はメスでしかみられないことがわかった。
それだけでなく、オスではむしろ糖代謝が悪化し、悪い影響を及ぼすことも明らかになった。もし慣例に従ってオスのみを用いて実験していたら、オステオカルシンの有用性が見逃されていた。
こうした性差を意識した動きは、「『ジェンダード・イノベーションズ＝性差研究に基づく技術革新』と呼ばれ、世界的に注目されている。

研究開発の現場では、動物実験を行う際にオスのみを使って実験を行うことが多い。しかし、単に体格の差だけでなく、体内での機能における男女差が薬の効きの違いや疾患の感受性の違いを生む可能性があることが明らかにされつつある。
我々は、骨基質タンパク質であるオステオカルシンを長期間経口投与すると全身の代謝が活性化することをマウスの実験で明らかにしたが、オス・メス両性のマウスを用いて実験した結果、代謝改善効果はメスでしかみられないことがわかった。
それだけでなく、オスではむしろ糖代謝が悪化し、悪い影響を及ぼすことも明らかになった。もし慣例に従ってオスのみを用いて実験していたら、オステオカルシンの有用性が見逃されていた。
こうした性差を意識した動きは、「『ジェンダード・イノベーションズ＝性差研究に基づく技術革新』と呼ばれ、世界的に注目されている。

骨基質タンパク質であるオステオカルシンが、経口投与でマウスの代謝活性化を促進するという研究成果について。
また、オステオカルシンが豚骨スープを抽出した後の廃棄豚骨からも抽出できる可能性があることについて。

骨基質タンパク質であるオステオカルシンを長期間経口投与すると全身の代謝が活性化することをマウスの実験で明らかにした。
また、経口投与したオステオカルシンはわずかではあるが有効な量が小腸に達し、少なくとも２４時間はそこに留まって作用を及ぼし続けることも明らかにした。