研究者業績
基本情報
研究キーワード
5経歴
5-
2017年5月
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2013年4月 - 2017年4月
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2008年4月 - 2013年3月
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2007年4月 - 2008年3月
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1995年4月 - 1998年3月
学歴
2-
1998年4月 - 2002年3月
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1989年4月 - 1995年3月
論文
132-
Journal of the American Society of Nephrology 27(9) 2685-2700 2016年9月 査読有り
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PLOS ONE 11(6) e0157497 2016年6月 査読有りNephrin is a critical component of glomerular filtration barrier, which is important to maintain glomerular structure and avoid proteinuria. Downregulation of nephrin expression is commonly observed at early stage of glomerular disorders, suggesting that methods to increase nephrin expression in podocytes may have therapeutic utility. Here, we generated a knockin mouse line carrying single copy of 5.5 kb nephrin promoter controlling expression of enhanced green fluorescent protein (EGFP) at Rosa26 genomic locus (Nephrin-EGFP mouse). In these mice, EGFP was specifically expressed in podocytes. Next, we isolated and cultivated glomeruli from these mice, and developed a protocol to automatically quantitate EGFP expression in cultured glomeruli. EGFP signal was markedly reduced after 5 days of culture but reduction was inhibited by vitamin D treatment. We confirmed that vitamin D increased mRNA and protein expression of endogenous nephrin in cultivated glomeruli. Thus, we generated a mouse line converting nephrin promoter activity into fluorescence, which can be used to screen compounds having activity to enhance nephrin gene expression.
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Pathogenesis and Treatment in IgA Nephropathy: An International Comparison 89-96 2016年3月10日 査読有りTwo evidence-based histological classifications, the Oxford and Japanese histological grade classification (JHGC), have been recently developed. However, they differ on a number of points both in the methodological approach to developing the classification schemes, classification system (split or lumped), and in the predictive pathological parameters. As these two classification systems coexist in Japan, there has been a great deal of motivation to compare the two in order to try and determine which approach may produce the most informative information for the sake of clinicians and ultimately for the benefit of the patients. Even though JHGC was not produced with the same rigor as the Oxford classification, its utility can be evaluated by the clinical information that it provides. For the aim to overcome the task of histological classification, JHGC may not be inferior to Oxford classification.
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DIABETES 65(3) 755-767 2016年3月 査読有りOvercoming refractory massive proteinuria remains a clinical and research issue in diabetic nephropathy. This study was designed to investigate the pathogenesis of massive proteinuria in diabetic nephropathy, with a special focus on podocyte autophagy, a system of intracellular degradation that maintains cell and organelle homeostasis, using human tissue samples and animal models. Insufficient podocyte autophagy was observed histologically in patients and rats with diabetes and massive proteinuria accompanied by podocyte loss, but not in those with no or minimal proteinuria. Podocyte-specific autophagy-deficient mice developed podocyte loss and massive proteinuria in a high-fat diet (HFD)-induced diabetic model for inducing minimal proteinuria. Interestingly, huge damaged lysosomes were found in the podocytes of diabetic rats with massive proteinuria and HFD-fed, podocyte-specific autophagy-deficient mice. Furthermore, stimulation of cultured podocytes with sera from patients and rats with diabetes and massive proteinuria impaired autophagy, resulting in lysosome dysfunction and apoptosis. These results suggest that autophagy plays a pivotal role in maintaining lysosome homeostasis in podocytes under diabetic conditions, and that its impairment is involved in the pathogenesis of podocyte loss, leading to massive proteinuria in diabetic nephropathy. These results may contribute to the development of a new therapeutic strategy for advanced diabetic nephropathy.
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Diabetes 65(3) 755-67 2016年3月 査読有りOvercoming refractory massive proteinuria remains a clinical and research issue in diabetic nephropathy. This study was designed to investigate the pathogenesis of massive proteinuria in diabetic nephropathy, with a special focus on podocyte autophagy, a system of intracellular degradation that maintains cell and organelle homeostasis, using human tissue samples and animal models. Insufficient podocyte autophagy was observed histologically in patients and rats with diabetes and massive proteinuria accompanied by podocyte loss, but not in those with no or minimal proteinuria. Podocyte-specific autophagy-deficient mice developed podocyte loss and massive proteinuria in a high-fat diet (HFD)-induced diabetic model for inducing minimal proteinuria. Interestingly, huge damaged lysosomes were found in the podocytes of diabetic rats with massive proteinuria and HFD-fed, podocyte-specific autophagy-deficient mice. Furthermore, stimulation of cultured podocytes with sera from patients and rats with diabetes and massive proteinuria impaired autophagy, resulting in lysosome dysfunction and apoptosis. These results suggest that autophagy plays a pivotal role in maintaining lysosome homeostasis in podocytes under diabetic conditions, and that its impairment is involved in the pathogenesis of podocyte loss, leading to massive proteinuria in diabetic nephropathy. These results may contribute to the development of a new therapeutic strategy for advanced diabetic nephropathy.
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Autophagy 12(1) 1-222 2016年1月2日
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Journal of the American Society of Nephrology 27(9) 2685-2700 2016年 査読有りStudies have revealed many analogies between podocytes and neurons, and these analogies may be key to elucidating the pathogenesis of podocyte injury. Cathepsin D (CD) is a representative aspartic proteinase in lysosomes. Central nervous system neurons in CD-deficientmice exhibit a formof lysosomal storage disease with a phenotype resembling neuronal ceroid lipofuscinoses. In the kidney, the role of CD in podocytes has not been fully explored. Herein, we generated podocyte-specific CD-knockout mice that developed proteinuria at 5 months of age and ESRD by 20-22 months of age. Immunohistochemical analysis of these mice showed apoptotic podocyte death followed by proteinuria and glomerulosclerosis with aging. Using electron microscopy, we identified, in podocytes, granular osmiophilic deposits (GRODs), autophagosome/autolysosome-like bodies, and fingerprint profiles, typical hallmarks of CDdeficient neurons. CD deficiency in podocytes also led to the cessation of autolysosomal degradation and accumulation of proteins indicative of autophagy impairment and the mitochondrial ATP synthase subunit c accumulation in the GRODs, again similar to changes reported in CD-deficient neurons. Furthermore, both podocin and nephrin, two essential components of the slit diaphragm, translocated to Rab7-andlysosome-associatedmembraneglycoprotein1-positive amphisomes/autolysosomes that accumulated in podocyte cell bodies in podocyte-specific CD-knockout mice. We hypothesize that defective lysosomal activity resulting in foot process effacement caused this accumulation of podocin and nephrin. Overall, our results suggest that loss ofCDinpodocytes causes autophagy impairment, triggering the accumulationof toxic subunit c-positive lipofuscins as well as slit diaphragm proteins followed by apoptotic cell death.
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日本生化学会大会・日本分子生物学会年会合同大会講演要旨集 88回・38回 [4T8L-05(3P0494)] 2015年12月
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Scientific reports 5 18575 2015年12月 査読有り
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Podocyte-specific deletion of Rac1 leads to aggravation of renal injury in STZ-induced diabetic miceBiochemical and Biophysical Research Communications 467(3) 549-555 2015年11月20日 査読有りRac1, a GTPase of the Rho subfamily, has a crucial role in cytoskeletal architecture, as well as the regulation of cell migration and growth. However, renal injury in mice with podocyte-specific deletion of Rac1 has yet to be elucidated fully due to conflicting findings. Herein, we identified a possible role for Rac1 in podocytes of streptozotocin- (STZ) induced diabetic mice. The urinary albumin/creatinine ratio (ACR) in the knockout (KO) group was significantly higher than that in the wild type (WT) group at any week of age. A more marked ACR increase was observed in STZ/KO group than STZ/WT group, although ACR did increase with weeks of age in both diabetic groups. The kidney sections from diabetic mice revealed a glomerular hypertrophy with mesangial expansion, but there was no appreciable difference in glomerular findings under a light microscope between STZ/WT and STZ/KO mice. However, an electron microscopy analysis revealed that regardless of the presence or absence of diabetes, both KO (KO and STZ/KO) groups had a higher rate of foot process effacement compared with both WT (WT and STZ/WT) groups. The expression levels of the slit diaphragm protein, podocin, was reduced with the induction of diabetes, and the levels in the STZ/KO group experienced a further reduction compared with the STZ/WT group. The number of WT1-positive cells in the STZ/KO group was more significantly decreased than that in the other three groups. In contrast, the numbers of cleaved caspase 3- and TUNEL-positive cells in the glomeruli of the STZ/KO group were more increased than those in the STZ/WT group. Thus, this study provides evidence that podocyte-specific deletion of Rac1 results in morphological alteration in podocytes, and that the induction of apoptosis or decreased expression of the slit diaphragm proteins by hyperglycemic stimuli are associated with the progression of diabetic nephropathy.
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Biochemical and biophysical research communications 467(3) 549-555 2015年11月 査読有り
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Free radical biology & medicine 87 181-92 2015年10月 査読有りThe contribution of endothelial nitric oxide synthase (eNOS) to podocyte integrity remains unclear. This study therefore examined podocytes and mitochondrial abnormalities in eNOS deficient mice. Absence of eNOS caused glomerular hypertrophy, along with occasional glomerular sclerosis and mesangiolysis. While many glomeruli did not have such advanced lesions, ultrastructural analysis showed cellular hypertrophy, vacuolization, lysosomal enlargement, and microvillus formation in podocytes of eNOS knockout (KO) mice. Increased oxidative stress was associated with mitochondrial abnormalities, including an increase in number, coupled with a reduction in size, of mitochondria in podocytes of eNOS-KO mice. While the levels of expression of several mitochondrial proteins were not altered, the d-17 mutation in mitochondrial DNA was significantly associated with the eNOS deficiency. Renal ATP level in the renal cortex and mitochondrial respiration in the primary podocytes were significantly lower in eNOS-KO mice, suggesting that renal mitochondria may be functionally impaired. Podocytes cultured with endothelial conditioned medium lacking NO consistently showed a greater degree of mitochondrial fragmentation and an increase in mitochondrial oxidative stress, with these mitochondrial alterations rescued by an NO donor. In conclusion, eNOS may be necessary to maintain podocyte integrity, especially mitochondrial function.
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Free radical biology & medicine 2015年6月 査読有り
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Cell and tissue research 360(2) 391-400 2015年5月 査読有り
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Cell and Tissue Research 360(2) 391-400 2015年5月1日 査読有りPodocytes serve as the final barrier to urinary protein loss through a highly specialized structure called a slit membrane and maintain foot process and glomerular basement membranes. Podocyte injury results in progressive glomerular damage and accelerates sclerotic changes, although the exact mechanism of podocyte injury is still obscure. We focus on the staining gap (podocin gap) defined as the staining difference between podocin and synaptopodin, which are normally located in the foot process. In puromycin aminonucleoside nephrosis rats, the podocin gap is significantly increased (p < 0.05) and podocin is translocated to the cytoplasm on days 7 and 14 but not on day 28. Surprisingly, the gap is also significantly increased (p < 0.05) in human kidney biopsy specimens of poor-prognosis IgA nephropathy patients. This suggests that the podocin gap could be a useful marker for classifying the prognosis of IgA nephropathy and indicating the translocation of podocin to the cytoplasm. Next, we find more evidence of podocin trafficking in podocytes where podocin merges with Rab5 in puromycin aminonucleoside nephrosis rats at day 14. In immunoelectron microscopy, the podocin positive area was significantly translocated from the foot process areas to the cytoplasm (p< 0.05) on days 7 and 14 in puromycin aminonucleoside nephrosis rats. Interestingly, podocin is also translocated to the cytoplasm in poor-prognosis human IgA nephropathy. In this paper, we demonstrate that the translocation of podocin by endocytosis could be a key traffic event of critical podocyte injury and that the podocin gap could indicate the prognosis of IgA nephropathy.
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順天堂醫事雑誌 61(1) 34-40 2015年Objective: Podocytes play an important role in maintaining the structural integrity and function of the glomerular filtration barrier. Adriamycin (ADR) -induced podocyte injury has been extensively studied, however, its mechanism remains unclear. In the present study, we aimed to explore novel genes associated with podocyte injury induced by ADR.Methods: A microarray assay was carried out on isolated podocytes with and without ADR treatment and analyzed using Genespring GX software. Two genes, Fos-like antigen 1 (FOSL1) and Regulator of G-protein signaling 2 (RGS2) were selected as candidate genes because their levels showed the most significant changes after ADR-induced podocyte injury. To confirm the changes in mRNA levels and their protein expression, ADR was added to cultured mouse podocytes and analyzed at 1, 2, 6, and 24 hours using real-time PCR and immunofluorescence. Finally, we also confirmed the expression of both proteins in vivo, by staining mouse kidney tissue at 0, 3, and 15 days after ADR injection.Results: Microarray data showed that after ADR treatment, FOSL1 was up-regulated, while RGS2 was down-regulated. Real-time PCR analysis confirmed that ADR induced a significant increase of FOSL1 at 24 hours (p < 0.001, 24 h vs. control), and a marked down-regulation of RGS2 (p < 0.001, at each time point vs. control). Immunofluorescence analysis of podocytes treated with ADR for 24 hours showed an up-regulation tendency for FOSL1 protein and a down-regulation tendency for RGS2. On ADR-induced injury mice specimens, the expression of FOSL1 was increased in a time dependent manner after the injection; on the other hand, RGS2 was down-regulated, especially 15 days after injection.Conclusion: FOSL1 and RGS2 were both expressed in podocytes, and were significantly regulated after ADR treatment, revealing a possible role in podocyte injury induced by ADR. These results could help guide research further to finally elucidate the underlying mechanisms in podocyte injury.
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NEPHRON 129(2) 143-154 2015年 査読有りBackground: Blockade of the renin-angiotensin system plays a key role in suppressing the progression of renal diseases. It has not been well established whether this therapy provides additional effects when combined with vitamin D or its analog in a model of adriamycin (ADR)-induced nephropathy. Methods: We evaluated the effect of an angiotensin II subtype 1 receptor blocker (telmisartan) combined with a vitamin D analog (oxacalcitriol) on mice ADR-induced nephropathy (9.5 mg/kg single intravenous injection). We also tested immortalized murine podocytes to examine the effects on podocyte apoptosis. Results: Mice with ADR-induced nephropathy developed progressive albuminuria and glomerulosclerosis within 30 days accompanied by decreased expression of slit diaphragm (SD)-associated proteins (nephrin and podocin), reduced numbers of podocytes, and increased systolic blood pressure. Treatment with telmisartan or oxacalcitriol alone moderately ameliorated kidney injury. The combined treatment most effectively reduced the albuminuria and glomerulosclerosis. These effects were accompanied by the restoration of SD-associated proteins, reduction of podocyte apoptosis, and prevention of podocyte depletion in the glomeruli. Treatment with telmisartan, oxacalcitriol, and the combination therapy resulted in similar reductions in systolic blood pressure. In cultured murine podocytes, ADR stimulated the expression of Bax/Bcl-2 and apoptosis as determined by Hoechst 33342 staining. These changes were effectively inhibited by telmisartan or oxacalcitriol, but the combination treatment most effectively reduced these effects. Conclusions: These data demonstrated that application of a renin-angiotensin system blocker plus a vitamin D analog effectively prevented renal injury in ADR-induced nephropathy. The observed amelioration of renal injury may be partly attributable to antiapoptotic effects in podocytes. (C) 2015 S. Karger AG, Basel
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Japanese Journal of Clinical Immunology 38(1) 26-36 2015年It has recently become clear that initial glomerular injury affects glomerular visceral epithelial cells (also called as podocytes) as important target cells for progression of chronic kidney disease (CKD) and end-stage kidney disease. Podocytes are injured in many human kidney diseases including minimal change disease, focal segmental glomerulosclerosis, diabetic nephropathy, membranous nephropathy and lupus nephritis. Podocytes are highly specialized epithelial cells that cover the outer layer of the glomerular basement membrane (GBM). Podocytes serve as the final barrier to urinary protein loss through the special formation and maintenance of foot-processes and an interposed slit-diaphragm. Chronic podocyte injury may cause podocyte detachment from the GBM, which leads to glomerulosclerosis. The elucidation of podocyte biology during the last 15 years has significantly improved our understanding of the pathophysiologic processes of proteinuria and glomerulosclerosis. In this review, we highlight some of new data including our recent findings for translating podocyte biology into new examinations and therapies for podocyte injury.
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Nephron 129(2) 143-54 2015年1月 査読有り
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PLOS ONE 9(12) e114400 2014年12月 査読有りBackground and Objectives: Megalin is highly expressed at the apical membranes of proximal tubular epithelial cells. A urinary full-length megalin (C-megalin) assay is linked to the severity of diabetic nephropathy in type 2 diabetes. This study examined the relationship between levels of urinary C-megalin and histological findings in adult patients with IgA nephropathy (IgAN). Design, Setting, Participants, & Measurements: Urine samples voided in the morning on the day of renal biopsy were obtained from 73 patients with IgAN (29 men and 44 women; mean age, 33 years) and 5 patients with membranous nephropathy (MN). Renal pathologic variables were analyzed using the Oxford classification of IgAN, the Shigematsu classification and the Clinical Guidelines of IgAN in Japan. The levels of urinary C-megalin were measured by sandwich ELISA. Results: Histological analysis based on the Oxford classification revealed that the levels of urinary C-megalin were correlated with mesangial hypercellularity in IgAN patients (OR=1.76, 95% CI: 1.04-3.27, P<0.05). There was a significant correlation between the levels of urinary C-megalin and the severity of chronic extracapillary abnormalities according to the Shigematsu classification in IgAN patients (beta=0.33, P=0.008). The levels of urinary C-megalin were significantly higher in all risk levels of IgAN patients requiring dialysis using the Clinical Guidelines of IgAN in Japan than in the control group. The levels of urinary C-megalin were significantly higher in the high risk and very high risk grades than in the low risk grade (P<0.05). The levels of urinary C-megalin were significantly higher in MN patients compared to the control group. Conclusions: The levels of urinary C-megalin are associated with histological abnormalities in adult IgAN patients. There is a possibility that urinary C-megalin is
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AMERICAN JOURNAL OF PATHOLOGY 184(10) 2699-2708 2014年10月 査読有りMembrane-associated guanylate kinase inverted 2 (MAGI-2) is a tight junction protein in epithelial tissues. We previously reported the detailed expression patterns of MAGI-2 in mouse tissues, including kidney podocytes, based on results obtained from Venus knock-in mice for Magi2 Locus. In the present study, homozygous deletion of the Magi2 gene in mice caused neonatal lethality, which was explained by podocyte morphological abnormalities and anuria. Immunohistological analysis showed that Loss of MAGI-2 function induced a significant decrease in nephrin and dendrin at the slit diaphragm of the kidney, although other components of the slit diaphragm were unchanged. Furthermore, nuclear translocation of dendrin was observed in the podocytes of the MAGI-2 null mutants, along with enhanced expression of cathepsin L, which is reported to be critical for rearrangement of the actin cytoskeleton in podocytes. Expression analysis of the null mutants showed that Loss of MAGI-2 function induces abnormal expression of various types of adhesion-related molecules. The present study is the first to demonstrate that MAGI-2 has a critical role in maintaining the functional structure of the slit diaphragm and that this molecule has an essential role in the functioning of the kidney filtration barrier.
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Biochemical and biophysical research communications 454(4) 531-536 2014年10月 査読有り
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CLINICAL NEPHROLOGY 81(6) 445-450 2014年6月 査読有りCastleman's disease (CD) is a lymphoproliferative disorder of uncertain etiology. It can be classified histopathologically as hyaline vascular (HV) or plasma cell (PC) type; and clinically as unicentric or multicentric. Multicentric CD mostly manifests as the PC type and is often associated with a variety of systemic complications, although renal complications are uncommon. We present here a case of HV type, unicentric CD with a variety of systemic and renal complications, including the proliferation of glomerular endothelial cells. Various cytokines are thought to be involved in the etiology of this disease, especially interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF), which are the main cytokines inducing systemic complications. It has been reported that most PC types and/or multicentric types of CD show increasing levels of serum IL-6 and VEGF, as well as systemic symptoms. Although the current case showed high serum IL-6 and VEGF levels as well as systemic symptoms, the pathological and clinical type were of the HV type and unicentric type, respectively. After immunosuppressive therapy, the serum levels of IL-6 and VEGF returned to the normal range, and systemic complications, including renal involvement, also improved. We report the possibility of pathogenesis via the serum and the pathology of this rare case.
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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 446(4) 1190-1196 2014年4月18日 査読有り
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Biochemical and biophysical research communications 446(4) 1190-1196 2014年4月18日 査読有り
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NATURE COMMUNICATIONS 5 3296 2014年2月 査読有りActivation of Notch1 and Notch2 has been recently implicated in human glomerular diseases. Here we show that Notch2 prevents podocyte loss and nephrosis. Administration of a Notch2 agonistic monoclonal antibody ameliorates proteinuria and glomerulosclerosis in a mouse model of nephrosis and focal segmental glomerulosclerosis. In vitro, the specific knockdown of Notch2 increases apoptosis in damaged podocytes, while Notch2 agonistic antibodies enhance activation of Akt and protect damaged podocytes from apoptosis. Treatment with triciribine, an inhibitor of Akt pathway, abolishes the protective effect of the Notch2 agonistic antibody. We find a positive linear correlation between the number of podocytes expressing activated Notch2 and the number of residual podocytes in human nephrotic specimens. Hence, specific activation of Notch2 rescues damaged podocytes and activating Notch2 may represent a novel clinical strategy for the amelioration of nephrosis and glomerulosclerosis.
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Nihon yakurigaku zasshi. Folia pharmacologica Japonica 143(1) 27-33 2014年1月
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American Journal of Pathology 184(10) 2699-2708 2014年 査読有りMembrane-associated guanylate kinase inverted 2 (MAGI-2) is a tight junction protein in epithelial tissues. We previously reported the detailed expression patterns of MAGI-2 in mouse tissues, including kidney podocytes, based on results obtained from Venus knock-in mice for Magi2 locus. In the present study, homozygous deletion of the Magi2 gene in mice caused neonatal lethality, which was explained by podocyte morphological abnormalities and anuria. Immunohistological analysis showed that loss of MAGI-2 function induced a significant decrease in nephrin and dendrin at the slit diaphragm of the kidney, although other components of the slit diaphragm were unchanged. Furthermore, nuclear translocation of dendrin was observed in the podocytes of the MAGI-2enull mutants, along with enhanced expression of cathepsin L, which is reported to be critical for rearrangement of the actin cytoskeleton in podocytes. Expression analysis of the null mutants showed that loss of MAGI-2 function induces abnormal expression of various types of adhesion-related molecules. The present study is the first to demonstrate that MAGI-2 has a critical role in maintaining the functional structure of the slit diaphragm and that this molecule has an essential role in the functioning of the kidney filtration barrier.
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Microvascular research 88 79-83 2013年7月 査読有り
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Nephrology Dialysis Transplantation 28(7) 1762-1772 2013年7月 査読有りBackground. It has been reported that podocytopenia has been occurring with increasing disease severity in patients with IgA nephropathy (IgAN). Dendrin is localized at the slit diaphragm (SD) in podocytes. We showed that dendrin translocates to the nucleus of injured podocytes in experimental nephritis and the nuclear dendrin promotes podocyte apoptosis. It is still unknown whether dendrin translocates from the SD to podocyte nucleus in IgAN. We investigated the presence of nuclear dendrin in patients with IgAN and the association between the translocated dendrin to the podocyte nucleus and disease activity. Methods. Fourteen adult patients with IgAN were enrolled. The pathological parameters were analyzed. Immunostaining of renal biopsy specimens and urinary sediments from IgAN or minimal change nephrotic syndrome (MCNS) as the control was performed. Results. A positive correlation was observed between an acute extracapillary change and the number of dendrin-positive nuclei. The location of dendrin in the nuclei was found in urinary podocytes of IgAN. The number of dendrin-positive nuclei in urinary podocytes of IgAN was significantly higher than that of MCNS. Urinary podocytes, which expressed the apoptosis marker annexin V, were also detected in IgAN. The translocation of dendrin to the podocyte nucleus as well as strong cathepsin L staining were detected in the glomeruli of IgAN. Conclusion. An increasing number of dendrin-positive nuclei in the glomeruli suggest acute glomerular injury in IgAN. Apoptotic podocytes were detectable in the urine of IgAN. It appears that the translocation of dendrin to the podocyte nuclei enhances podocyte apoptosis in acute glomerular injury and leads to podocytopenia in patients with IgAN. © The Author 2013.
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Microvascular research 88 79-83 2013年7月 査読有り
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Journal of Biological Chemistry 288(24) 17057-17062 2013年6月14日 査読有りKidney podocytes are highly specialized terminally differentiated cells that form the final barrier to urinary protein loss. Podocytes are a target for injury by metabolic, autoimmune, hereditary, inflammatory, and other stressors. Persistence of podocyte injury leads to podocyte death and loss, which results in progressive kidney damage and ultimately kidney failure. Dendrin is a dual compartment protein with proapoptotic signaling properties. Nuclear relocation of dendrin in response to glomerular injury promotes podocyte apoptosis. Here we show that Yes-associated protein (YAP), a downstream target of Hippo kinases and an inhibitor of apoptosis, is expressed in the nucleus of podocytes. The WW domains of YAP mediate the interaction with the PPXY motifs of dendrin. This interaction is functionally relevant because YAP binding to dendrin reduces dendrin-dependent, staurosporine-induced apoptosis in co-transfected HEK293 cells. Moreover gene silencing of YAP in podocytes increases adriamycin-induced podocyte apoptosis. It also increases staurosporine-induced caspase-3/7 activity, which is rescued by dendrin depletion in YAP knockdown cells. Our findings elucidate YAP binding to dendrin as a prosurvival mechanism. The antiapoptotic signaling properties of YAP in podocytes could hold significance in the quest for targeted therapeutics aimed at preventing podocyte loss. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.
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Microvascular Research 110 65 2013年3月1日 査読有りThe authors regret the right photo in Fig. 1: Should be the photo below. The authors would like to apologize for any inconvenience caused.
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順天堂醫事雑誌 59(5) 398-406 2013年Glomerular visceral epithelial cells, also known as podocytes, are highly specialized epithelial cells that cover the outer layer of the glomerular basement membrane (GBM). Podocytes serve as the final barrier to urinary protein loss through the special formation and maintenance of foot processes (FPs) and an interposed slit diaphragm (SD). Chronic podocyte injury may cause podocyte detachment from the GBM, which leads to glomerulosclerosis. The elucidation of podocyte biology during the last decade has significantly improved our understanding of the pathophysiologic processes of proteinuria and glomerulosclerosis. This review highlights some of the recent findings for translating podocyte biology into new therapies and examinations for podocyte injury.
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Microvascular Research 87 100 2013年 査読有り
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Microvascular research 85 54-58 2013年1月 査読有り
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Microvascular Research 85(1) 54-58 2013年1月 査読有りAdvanced glycation end products (AGEs) formed at an accelerated rate under diabetes, elicit oxidative and pro-apoptotic reactions in various types of cells, including podocytes, thus being involved in the development and progression of diabetic nephropathy. Recently, we, along with others, have found that pigment epithelium-derived factor (PEDF), a glycoprotein with potent neuronal differentiating activity, inhibits AGE-elicited mesangial and tubular cell damage through its anti-oxidative properties. However, the effects of PEDF on podocyte loss, one of the characteristic features of diabetic nephropathy remain unknown. In this study, we investigated whether and how PEDF could protect against AGE-elicited podocyte apoptosis in vitro. AGEs decreased PEDF mRNA level in podocytes, which was blocked by neutralizing antibody raised against receptor for AGEs (RAGE-Ab). PEDF or RAGE-Ab was found to inhibit the AGE-induced up-regulation of RAGE mRNA level, oxidative stress generation and resultant apoptosis in podocytes. All of the beneficial effects of PEDF on AGE-exposed podocytes were blocked by the treatment of GW9662, an inhibitor of peroxisome proliferator-activated receptor-γ (PPARγ). Further, although PEDF did not affect protein expression levels of PPARγ, it significantly restored the PPARγ transcriptional activity in AGE-exposed podocytes. The present results demonstrated for the first time that PEDF could block the AGE-induced apoptotic cell death of podocytes by suppressing RAGE expression and subsequent ROS generation partly via PPARγ activation. Our present study suggests that substitution of PEDF proteins may be a promising strategy for preventing the podocyte loss in diabetic nephropathy. © 2012 Elsevier Inc.
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Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association 2012年11月 査読有り
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Clinical journal of the American Society of Nephrology : CJASN 7 1385-1393 2012年9月 査読有り
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Clinical journal of the American Society of Nephrology : CJASN 7(9) 1385-1393 2012年9月1日 査読有りOwner : NLM<br /> Status : MEDLINE<br /> PubModel : Print-Electronic<br /> Language : eng<br /> Pagination : 1385-93
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Journal of clinical laboratory analysis 26 248-253 2012年7月 査読有り
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Journal of Clinical Laboratory Analysis 26(4) 248-253 2012年7月 査読有りBackground: Accurate estimation of the glomerular filtration rate (GFR) is very important in clinical practice. Although renal inulin clearance (Cin) is the gold standard for measuring GFR, the procedure for Cin measurement is complicated. Use of GFR-estimating equations has been increasing recently due to their simplicity. The objectives of the present study are to analyze the correlation between Cin and other GFR-estimating parameters and to investigate their clinical usefulness and limitation. Methods: Seventy-two Japanese patients were enrolled in this study. Cin was measured by the continuous infusion method. Serum creatinine (s-Cr), cystatin C, uric acid (UA), and hemoglobin (Hb) were measured. The Japanese formula of estimated GFR (eGFR) was as follows: eGFR (ml/min/1.73m2) = 194 × s-Cr-1.094 × Age-0.287 × 0.739 (if female). The endogenous creatinine clearance test was also performed. Results: Levels of Cin were highly correlated with those of endogenous creatinine clearance (Ccr) (R2 = 0.7585) and eGFR (R2 = 0.5659). However, patients with lower Cin showed unexpectedly elevated levels of endogenous Ccr and eGFR. Moreover, the levels of eGFR tended to be unexpectedly increased in patients with low body surface area. Conclusion: Although GFR-estimating equations are useful for estimating GFR accurately, they pose a risk of overestimation of kidney function in patients with decreased GFRor a poor physique. © 2012 Wiley Periodicals, Inc.
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日本内科学会雑誌 101(4) 1092-1101 2012年4月10日臨床の現場では，原因疾患を問わず腎障害の重要なマーカーとして蛋白尿が使用されている．正常人では高度な蛋白尿は認められないが，何らかの原因により血液の濾過装置である糸球体が障害を受けると，糸球体構成細胞の一つである糸球体足細胞（ポドサイト）が障害を受け，著明な蛋白尿が生じる．ポドサイトは高度に分化した細胞であり，糸球体内皮細胞と糸球体基底膜を外側から覆い，血中蛋白質の最終的な濾過障壁としての機能を果たしている．ポドサイト障害の早期には，まずスリット膜の分子構造の変化と足突起の細胞骨格であるアクチン骨格の分布が変化し，足突起は消失してその噛み合わせを失う．ポドサイト障害が長く持続すると糸球体基底膜上からポドサイトは脱落し，糸球体硬化・慢性腎不全へと進行して行く．最近，ポドサイト障害から糸球体硬化にいたるメカニズムが，分子生物学的手法を用い急速に解明されつつあり，ポドサイトのアクチン骨格再構成・細胞死・オートファジーなどが関係することがわかってきた．ポドサイトにおけるこれらの機序の解明とともに，ポドサイトにターゲットを絞った新規治療薬が検索されつつある．<br>
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Nihon Naika Gakkai zasshi. The Journal of the Japanese Society of Internal Medicine 101(4) 1092-101 2012年4月
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AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY 302(3) F380-F389 2012年2月 査読有り
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American Journal of Physiology - Renal Physiology 302(3) F380-F389 2012年2月 査読有りAutophagy is a process of cellular degradation, and its dysfunction elicits many pathological symptoms. However, the contribution of autophagy to kidney glomerular function has not been fully clarified. We previously reported that LC3, a promising executor of autophagy, played an important role in recovery from podocyte damage in an experimental nephrosis model (Asanuma K, Tanida I, Shirato I, Ueno T, Takahara H, Nishitani T, Kominami E, Tomino Y. FASEB J 17: 1165-1167, 2003). γ-Aminobutyric acid A receptor-associated protein (GABARAP), has recently been characterized as another homolog of LC3, although its precise role in autophagy remains unclear. We recently generated green fluorescent protein (GFP)-GABARAP transgenic mice, in which GFP-GABARAP is abundantly expressed in glomerular podocytes. We found that the transgenic mice showed no obvious phenotype, and podocytes isolated from these mice manifested autophagic activity almost equivalent to that of wild-type mice when measured in vitro. Surprisingly, a single injection of doxorubicin caused a greater increase in proteinuria and sclerotic glomeruli in transgenic mice compared with wild-type mice. Under these conditions, neither GFP-GABARAP nor endogenous GABARAP appeared to be recruited to autophagosomes, and both remained in the cytosol. Moreover, the cytosolic GFP-GABARAP was significantly colocalized with p62 to form aggregates. These results indicate that the GFP-GABARAP/p62 complex is responsible for impairment of glomerular function and that it retards recovery from the effects of doxorubicin. © 2012 the American Physiological Society.
MISC
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NEPHROLOGY DIALYSIS TRANSPLANTATION 33 55-55 2018年5月
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MICROVASCULAR RESEARCH 110 65-65 2017年3月
講演・口頭発表等
10担当経験のある科目(授業)
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腎臓内科学 (千葉大学)
共同研究・競争的資金等の研究課題
18-
日本学術振興会 科学研究費助成事業 基盤研究(B) 2023年4月 - 2026年3月
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2020年4月 - 2023年3月
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日本学術振興会 科学研究費助成事業 2018年4月 - 2021年3月
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科学研究費補助金(挑戦的萌芽研究) 2017年 - 2018年
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科学研究費補助金(挑戦的萌芽研究) 2014年 - 2016年