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Li F, Fang Y, Zhuang Q, Cheng M, Moronge D, Jue H, Meyuhas O, Ding X, Zhang Z, Chen JK, Wu H. Blocking ribosomal protein S6 phosphorylation inhibits podocyte hypertrophy and focal segmental glomerulosclerosis. Kidney Int 2022; 102:121-135. [PMID: 35483522 PMCID: PMC10711420 DOI: 10.1016/j.kint.2022.02.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 02/01/2022] [Accepted: 02/17/2022] [Indexed: 10/18/2022]
Abstract
Ribosomal protein S6 (rpS6) phosphorylation mediates the hypertrophic growth of kidney proximal tubule cells. However, the role of rpS6 phosphorylation in podocyte hypertrophy and podocyte loss during the pathogenesis of focal segmental glomerulosclerosis (FSGS) remains undefined. Here, we examined rpS6 phosphorylation levels in kidney biopsy specimens from patients with FSGS and in podocytes from mouse kidneys with Adriamycin-induced FSGS. Using genetic and pharmacologic approaches in the mouse model of FSGS, we investigated the role of rpS6 phosphorylation in podocyte hypertrophy and loss during development and progression of FSGS. Phosphorylated rpS6 was found to be markedly increased in the podocytes of patients with FSGS and Adriamycin-induced FSGS mice. Genetic deletion of the Tuberous sclerosis 1 gene in kidney glomerular podocytes activated mammalian target of rapamycin complex 1 signaling to rpS6 phosphorylation, resulting in podocyte hypertrophy and pathologic features similar to those of patients with FSGS including podocyte loss, leading to segmental glomerulosclerosis. Since protein phosphatase 1 is known to negatively regulate rpS6 phosphorylation, treatment with an inhibitor increased phospho-rpS6 levels, promoted podocyte hypertrophy and exacerbated formation of FSGS lesions. Importantly, blocking rpS6 phosphorylation (either by generating congenic rpS6 knock-in mice expressing non-phosphorylatable rpS6 or by inhibiting ribosomal protein S6 kinase 1-mediated rpS6 phosphorylation with an inhibitor) significantly blunted podocyte hypertrophy, inhibited podocyte loss, and attenuated formation of FSGS lesions. Thus, our study provides genetic and pharmacologic evidence indicating that specifically targeting rpS6 phosphorylation can attenuate the development of FSGS lesions by inhibiting podocyte hypertrophy and associated podocyte depletion.
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Affiliation(s)
- Fang Li
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China; Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Yili Fang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Department of Nephrology, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Qiyuan Zhuang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Meichu Cheng
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Nephrology, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Desmond Moronge
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Hao Jue
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Xiaoqiang Ding
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhigang Zhang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Jian-Kang Chen
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Huijuan Wu
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
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Zhang Y, Zhao J, Zhou BH, Tian EJ, Tian WS, Wang HW. iTRAQ-based quantitative proteomic analysis of low molybdenum inducing thymus atrophy and participating in immune deficiency-related diseases. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 216:112200. [PMID: 33862434 DOI: 10.1016/j.ecoenv.2021.112200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/10/2021] [Accepted: 03/25/2021] [Indexed: 06/12/2023]
Abstract
Molybdenum is a trace element with extremely uneven distribution in the environment. It constitutes the active sites of molybdenum enzymes that can catalyze redox reactions in almost all organisms. In this study, a mouse model with a low molybdenum diet was established to investigate the differential protein expressions in the thymus and the mechanism of molybdenum regulating thymocyte development. Results showed that the thymus evidently atrophied, and the weight and organ index of the thymus substantially decreased under the condition of low molybdenum (P < 0.01). A total of 274 differentially expressed proteins (DEPs) were screened through isobaric tag for relative and absolute quantification; amongst them, ribosomal proteins (38) were the most abundant. Bioinformatics analysis revealed that DEPs were mainly involved in protein metabolism (18%), nucleus (15%) and nucleic acid binding activity (17%), corresponding to biological process, cellular component and molecular function, respectively. Moreover, DEPs induced by low molybdenum were enriched in 94 pathways, of which typical maps including ribosome, oxidative phosphorylation and systemic lupus erythematosus. Flow cytometry analysis indicated the prominent imbalances of CD4+ and CD8+ cell ratios (P < 0.05, P < 0.01), suggesting the disordered development of T cell subsets. Overall, low molybdenum resulted in thymus atrophy by interfering with ribosomal protein expression and protein metabolism. This study provides a data platform for revealing the linkage between molybdenum and thymus-dependent immunity.
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Affiliation(s)
- Yan Zhang
- Henan Key Laboratory of Environmental and Animal Product Safety Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Jing Zhao
- Henan Key Laboratory of Environmental and Animal Product Safety Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Bian-Hua Zhou
- Henan Key Laboratory of Environmental and Animal Product Safety Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Er-Jie Tian
- Henan Key Laboratory of Environmental and Animal Product Safety Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Wei-Shun Tian
- College of Veterinary Medicine and Bio-safety Research Institute, Jeonbuk National University, Iksan 54596, South Korea
| | - Hong-Wei Wang
- Henan Key Laboratory of Environmental and Animal Product Safety Henan University of Science and Technology, Luoyang 471003, Henan, China.
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Zhuang Q, Li F, Liu J, Wang H, Tian Y, Zhang Z, Wang F, Zhao Z, Chen J, Wu H. Nuclear exclusion of YAP exacerbates podocyte apoptosis and disease progression in Adriamycin-induced focal segmental glomerulosclerosis. J Transl Med 2021; 101:258-270. [PMID: 33203894 PMCID: PMC7815513 DOI: 10.1038/s41374-020-00503-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 10/09/2020] [Accepted: 10/16/2020] [Indexed: 01/19/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a chronic glomerular disease with poor clinical outcomes. Podocyte loss via apoptosis is one important mechanism underlying the pathogenesis of FSGS. Recently, Yes-associated-protein (YAP), a key downstream protein in the Hippo pathway, was identified as an activator for multiple gene transcriptional factors in the nucleus to control cell proliferation and apoptosis. To investigate the potential role of YAP in the progression of FSGS, we examined kidney samples from patients with minimal change disease or FSGS and found that increases in podocyte apoptosis is positively correlated with the cytoplasmic distribution of YAP in human FSGS. Utilizing an established mT/mG transgenic mouse model and primary cultured podocytes, we found that YAP was distributed uniformly in nucleus and cytoplasm in the podocytes of control animals. Adriamycin treatment induced gradual nuclear exclusion of YAP with enhanced phospho-YAP/YAP ratio, accompanied by the induction of podocyte apoptosis both in vivo and in vitro. Moreover, we used verteporfin to treat an Adriamycin-induced FSGS mouse model, and found YAP inhibition by verteporfin induced nuclear exclusion of YAP, thus increasing podocyte apoptosis and accelerating disease progression. Therefore, our findings suggest that YAP nuclear distribution and activation in podocytes is an important endogenous anti-apoptotic mechanism during the progression of FSGS.
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Affiliation(s)
- Qiyuan Zhuang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Fang Li
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jun Liu
- Department of Nephrology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hongyu Wang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yuchen Tian
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Zhigang Zhang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Feng Wang
- Department of Nephrology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Zhonghua Zhao
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Jianchun Chen
- Division of Nephrology in Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - Huijuan Wu
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
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Nechama M, Makayes Y, Resnick E, Meir K, Volovelsky O. Rapamycin and dexamethasone during pregnancy prevent tuberous sclerosis complex-associated cystic kidney disease. JCI Insight 2020; 5:136857. [PMID: 32484794 DOI: 10.1172/jci.insight.136857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/27/2020] [Indexed: 12/20/2022] Open
Abstract
Chronic kidney disease is the main cause of mortality in patients with tuberous sclerosis complex (TSC) disease. The mechanisms underlying TSC cystic kidney disease remain unclear, with no available interventions to prevent cyst formation. Using targeted deletion of TSC1 in nephron progenitor cells, we showed that cysts in TSC1-null embryonic kidneys originate from injured proximal tubular cells with high mTOR complex 1 activity. Injection of rapamycin to pregnant mice inhibited the mTOR pathway and tubular cell proliferation in kidneys of TSC1-null offspring. Rapamycin also prevented renal cystogenesis and prolonged the life span of TSC newborns. Gene expression analysis of proximal tubule cells identified sets of genes and pathways that were modified secondary to TSC1 deletion and rescued by rapamycin administration during nephrogenesis. Inflammation with mononuclear infiltration was observed in the cystic areas of TSC1-null kidneys. Dexamethasone administration during pregnancy decreased cyst formation by not only inhibiting the inflammatory response, but also interfering with the mTORC1 pathway. These results reveal mechanisms of cystogenesis in TSC disease and suggest interventions before birth to ameliorate cystic disease in offspring.
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Affiliation(s)
| | | | | | - Karen Meir
- Department of Pathology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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Fang Y, Li F, Qi C, Mao X, Wang F, Zhao Z, Chen JK, Zhang Z, Wu H. Metformin effectively treats Tsc1 deletion-caused kidney pathology by upregulating AMPK phosphorylation. Cell Death Discov 2020; 6:52. [PMID: 32566257 PMCID: PMC7295815 DOI: 10.1038/s41420-020-0285-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/18/2020] [Accepted: 05/28/2020] [Indexed: 12/25/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is characterized by hamartomatous lesions in multiple organs, with most patients developing polycystic kidney disease and leading to a decline of renal function. TSC is caused by loss-of-function mutations in either Tsc1 or Tsc2 gene, but currently, there is no effective treatment for aberrant kidney growth in TSC patients. By generating a renal proximal tubule-specific Tsc1 gene-knockout (Tsc1 ptKO) mouse model, we observed that Tsc1 ptKO mice developed aberrantly enlarged kidneys primarily due to hypertrophy and proliferation of proximal tubule cells, along with some cystogenesis, interstitial inflammation, and fibrosis. Mechanistic studies revealed inhibition of AMP-activated protein kinase (AMPK) phosphorylation at Thr-172 and activation of Akt phosphorylation at Ser-473 and Thr-308. We therefore treated Tsc1 ptKO mice with the AMPK activator, metformin, by daily intraperitoneal injection. Our results indicated that metformin increased the AMPK phosphorylation, but decreased the Akt phosphorylation. These signaling modulations resulted in inhibition of proliferation and induction of apoptosis in the renal proximal tubule cells of Tsc1 ptKO mice. Importantly, metformin treatment effectively prevented aberrant kidney enlargement and cyst growth, inhibited inflammatory response, attenuated interstitial fibrosis, and protected renal function. The effects of metformin were further confirmed by in vitro experiments. In conclusion, this study indicates a potential therapeutic effect of metformin on Tsc1 deletion-induced kidney pathology, although currently metformin is primarily prescribed to treat patients with type 2 diabetes.
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Affiliation(s)
- Yili Fang
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Fang Li
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Chenyang Qi
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Xing Mao
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Feng Wang
- Department of Nephrology, Shanghai 6th People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200032 PR China
| | - Zhonghua Zhao
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Jian-Kang Chen
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912 USA
| | - Zhigang Zhang
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Huijuan Wu
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
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Wang F, Yin J, Lin Y, Zhang F, Liu X, Zhang G, Kong Y, Lu Z, Wu R, Wang N, Xing T, Qian Y. IL-17C has a pathogenic role in kidney ischemia/reperfusion injury. Kidney Int 2020; 97:1219-1229. [DOI: 10.1016/j.kint.2020.01.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/18/2019] [Accepted: 01/03/2020] [Indexed: 01/14/2023]
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Liu T, Yuan J, Dai C, Xu J, Li S, Humphreys BD, Kleven DT, Chen JK. Cre/loxP approach-mediated downregulation of Pik3c3 inhibits the hypertrophic growth of renal proximal tubule cells. J Cell Physiol 2020; 235:9958-9973. [PMID: 32474911 DOI: 10.1002/jcp.29811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/21/2020] [Accepted: 05/13/2020] [Indexed: 11/08/2022]
Abstract
Nephron loss stimulates residual functioning nephrons to undergo compensatory growth. Excessive nephron growth may be a maladaptive response that sets the stage for progressive nephron damage, leading to kidney failure. To date, however, the mechanism of nephron growth remains incompletely understood. Our previous study revealed that class III phosphatidylinositol-3-kinase (Pik3c3) is activated in the remaining kidney after unilateral nephrectomy (UNX)-induced nephron loss, but previous studies failed to generate a Pik3c3 gene knockout animal model. Global Pik3c3 deletion results in embryonic lethality. Given that renal proximal tubule cells make up the bulk of the kidney and undergo the most prominent hypertrophic growth after UNX, in this study we used Cre-loxP-based approaches to demonstrate for the first time that tamoxifen-inducible SLC34a1 promoter-driven CreERT2 recombinase-mediated downregulation of Pik3c3 expression in renal proximal tubule cells alone is sufficient to inhibit UNX- or amino acid-induced hypertrophic nephron growth. Furthermore, our mechanistic studies unveiled that the SLC34a1-CreERT2 recombinase-mediated Pik3c3 downregulation inhibited UNX- or amino acid-stimulated lysosomal localization and signaling activation of mechanistic target of rapamycin complex 1 (mTORC1) in the renal proximal tubules. Moreover, our additional cell culture experiments using RNAi confirmed that knocking down Pik3c3 expression inhibited amino acid-stimulated mTORC1 signaling and blunted cellular growth in primary cultures of renal proximal tubule cells. Together, both our in vivo and in vitro experimental results indicate that Pik3c3 is a major mechanistic mediator responsible for sensing amino acid availability and initiating hypertrophic growth of renal proximal tubule cells by activation of the mTORC1-S6K1-rpS6 signaling pathway.
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Affiliation(s)
- Ting Liu
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Jialing Yuan
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Caihong Dai
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Jinxian Xu
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Shude Li
- Department of Biochemistry & Molecular Biology, School of Basic Medical Sciences, Kunming Medical University, Kunming, Yunnan, China
| | - Benjamin D Humphreys
- Division of Nephrology, Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Daniel T Kleven
- Department of Pathology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Jian-Kang Chen
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
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Cao H, Luo J, Zhang Y, Mao X, Wen P, Ding H, Xu J, Sun Q, He W, Dai C, Zen K, Zhou Y, Yang J, Jiang L. Tuberous sclerosis 1 (Tsc1) mediated mTORC1 activation promotes glycolysis in tubular epithelial cells in kidney fibrosis. Kidney Int 2020; 98:686-698. [PMID: 32739207 DOI: 10.1016/j.kint.2020.03.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 03/12/2020] [Accepted: 03/19/2020] [Indexed: 10/24/2022]
Abstract
Energy reprogramming to glycolysis is closely associated with the development of chronic kidney disease. As an important negative regulatory factor of the mammalian target of rapamycin complex 1 (mTORC1) signal, tuberous sclerosis complex 1 (Tsc1) is also a key regulatory point of glycolysis. Here, we investigated whether Tsc1 could mediate the progression of kidney interstitial fibrosis by regulating glycolysis in proximal tubular epithelial cells. We induced mTORC1 signal activation in tubular epithelial cells in kidneys with fibrosis via unilateral ureteral occlusion. This resulted in increased tubular epithelial cell proliferation and glycolytic enzyme upregulation. Prior incubation with rapamycin inhibited mTORC1 activation and abolished the enhanced glycolysis and tubular epithelial cell proliferation. Furthermore, knockdown of Tsc1 expression promoted glycolysis in the rat kidney epithelial cell line NRK-52E. Specific deletion of Tsc1 in the proximal tubules of mice resulted in enlarged kidneys characterized by a high proportion of proliferative tubular epithelial cells, dilated tubules with cyst formation, and a large area of interstitial fibrosis in conjunction with elevated glycolysis. Treatment of the mice with the glycolysis inhibitor 2-deoxyglucose notably ameliorated tubular epithelial cell proliferation, cystogenesis, and kidney fibrosis. Thus, our findings suggest that Tsc1-associated mTORC1 signaling mediates the progression of kidney interstitial fibrosis by regulating glycolysis in proximal tubular epithelial cells.
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Affiliation(s)
- Hongdi Cao
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Jing Luo
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yu Zhang
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaoming Mao
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ping Wen
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Hao Ding
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Jing Xu
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Qi Sun
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Weichun He
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chunsun Dai
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ke Zen
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University Advanced Institute of Life Sciences, Nanjing, Jiangsu, China
| | - Yang Zhou
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China.
| | - Junwei Yang
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China.
| | - Lei Jiang
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China.
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Liu T, Dai C, Xu J, Li S, Chen JK. The expression level of class III phosphatidylinositol-3 kinase controls the degree of compensatory nephron hypertrophy. Am J Physiol Renal Physiol 2020; 318:F628-F638. [PMID: 31904289 DOI: 10.1152/ajprenal.00381.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Excessive compensatory nephron hypertrophy (CNH) has been implicated in setting the stage for progressive nephron damage. Lack of a class III phosphatidylinositol 3-kinase (Pik3c3) inhibitor suitable for using in animals and lack of a Pik3c3-deficient animal model preclude the possibility of conclusively defining a role for Pik3c3 in CNH in previous studies. Here, we report that insertion of an Frt-flanked PGK-Neo cassette into intron 19 of the mouse Pik3c3 gene resulted in a hypomorphic allele. This allowed us to create a unique mouse model and provide the first definitive genetic evidence demonstrating whether Pik3c3 is essential for the regulation of CNH. Our results indicate that homozygous Pik3c3 hypomorphic (Pik3c3Hypo/Hypo) mice express significantly low levels of Pik3c3 than heterozygous Pik3c3 hypomorphic (Pik3c3Hypo/WT) littermates, which already express a lower level of Pik3c3 than wild-type (Pik3c3WT/WT) littermates. Interestingly, after unilateral nephrectomy (UNX), Pik3c3Hypo/Hypo mice develop a significantly lower degree of CNH than Pik3c3WT/WT mice and Pik3c3Hypo/WT mice, as revealed by measurement of kidney weight, kidney-to-body weight ratio, renal protein-to-DNA ratio, and morphometric analysis of proximal tubular and glomerular size. Mechanistically, UNX-induced mammalian target of rapamycin complex 1 (mTORC1) signaling to phosphorylation of ribosomal protein S6 (rpS6) in the remaining kidney was markedly inhibited in Pik3c3 hypomorphic mice. In conclusion, the present study reports a Pik3c3 hypomorphic mouse model and provides the first definitive evidence that Pik3c3 controls the degree of compensatory nephron hypertrophy. In addition, our signaling data provide the first definitive in vivo proof that Pik3c3 functions upstream of the mTORC1-S6 kinase 1-rpS6 pathway in the regulation of compensatory nephron hypertrophy.
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Affiliation(s)
- Ting Liu
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
| | - Caihong Dai
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
| | - Jinxian Xu
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
| | - Shude Li
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Kunming Medical University, Kunming, Yunnan, China
| | - Jian-Kang Chen
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
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10
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Maity S, Bera A, Ghosh-Choudhury N, Das F, Kasinath BS, Choudhury GG. microRNA-181a downregulates deptor for TGFβ-induced glomerular mesangial cell hypertrophy and matrix protein expression. Exp Cell Res 2018; 364:5-15. [PMID: 29397070 DOI: 10.1016/j.yexcr.2018.01.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 01/16/2018] [Indexed: 02/06/2023]
Abstract
TGFβ contributes to mesangial cell hypertrophy and matrix protein increase in various kidney diseases including diabetic nephropathy. Deptor is an mTOR-interacting protein and suppresses mTORC1 and mTORC2 activities. We have recently shown that TGFβ-induced inhibition of deptor increases the mTOR activity. The mechanism by which TGFβ regulates deptor expression is not known. Here we identify deptor as a target of the microRNA-181a. We show that in mesangial cells, TGFβ increases the expression of miR-181a to downregulate deptor. Decrease in deptor augments mTORC2 activity, resulting in phosphorylation/activation of Akt kinase. Akt promotes inactivating phosphorylation of PRAS40 and tuberin, leading to stimulation of mTORC1. miR-181a-mimic increased mTORC1 and C2 activities, while anti-miR-181a inhibited them. mTORC1 controls protein synthesis via phosphorylation of translation initiation and elongation suppressors 4EBP-1 and eEF2 kinase. TGFβ-stimulated miR-181a increased the phosphorylation of 4EBP-1 and eEF2 kinase, resulting in their inactivation. miR-181a-dependent inactivation of eEF2 kinase caused dephosphorylation of eEF2. Consequently, miR-181a-mimic increased protein synthesis and hypertrophy of mesangial cells similar to TGFβ. Anti-miR-181a blocked these events in a deptor-dependent manner. Finally, TGFβ-miR-181a-driven deptor downregulation increased the expression of fibronectin. Our results identify a novel mechanism involving miR-181a-driven deptor downregulation, which contributes to mesangial cell pathologies in renal complications.
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Affiliation(s)
- Soumya Maity
- Department of Medicine, UT Health San Antonio, TX, United States
| | - Amit Bera
- Department of Medicine, UT Health San Antonio, TX, United States
| | - Nandini Ghosh-Choudhury
- VA Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, TX, United States; Department of Pathology, UT Health San Antonio, TX, United States
| | - Falguni Das
- Department of Medicine, UT Health San Antonio, TX, United States; VA Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, TX, United States
| | - Balakuntalam S Kasinath
- Department of Medicine, UT Health San Antonio, TX, United States; VA Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, TX, United States
| | - Goutam Ghosh Choudhury
- Department of Medicine, UT Health San Antonio, TX, United States; VA Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, TX, United States; Geriatric Research, Education and Clinical Research Center, South Texas Veterans Health Care System, San Antonio, TX, United States.
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