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Semenikhina M, Lysikova DV, Spires DR, Domondon M, Stadler K, Palygin O, Ilatovskaya DV. Transcriptomic changes in glomeruli in response to a high salt challenge in the Dahl SS rat. Physiol Genomics 2024; 56:98-111. [PMID: 37955135 PMCID: PMC11281811 DOI: 10.1152/physiolgenomics.00075.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/31/2023] [Accepted: 11/04/2023] [Indexed: 11/14/2023] Open
Abstract
Salt sensitivity impacts a significant portion of the population and is an important contributor to the development of chronic kidney disease. One of the significant early predictors of salt-induced damage is albuminuria, which reflects the deterioration of the renal filtration barrier: the glomerulus. Despite significant research efforts, there is still a gap in knowledge regarding the molecular mechanisms and signaling networks contributing to instigating and/or perpetuating salt-induced glomerular injury. To address this gap, we used 8-wk-old male Dahl salt-sensitive rats fed a normal-salt diet (0.4% NaCl) or challenged with a high-salt diet (4% NaCl) for 3 wk. At the end of the protocol, a pure fraction of renal glomeruli obtained by differential sieving was used for next-generation RNA sequencing and comprehensive semi-automatic transcriptomic data analyses, which revealed 149 differentially expressed genes (107 and 42 genes were downregulated and upregulated, respectively). Furthermore, a combination of predictive gene correlation networks and computational bioinformatic analyses revealed pathways impacted by a high salt dietary challenge, including renal metabolism, mitochondrial function, apoptotic signaling and fibrosis, cell cycle, inflammatory and immune responses, circadian clock, cytoskeletal organization, G protein-coupled receptor signaling, and calcium transport. In conclusion, we report here novel transcriptomic interactions and corresponding predicted pathways affecting glomeruli under salt-induced stress.NEW & NOTEWORTHY Our study demonstrated novel pathways affecting glomeruli under stress induced by dietary salt. Predictive gene correlation networks and bioinformatic semi-automatic analysis revealed changes in the pathways relevant to mitochondrial function, inflammatory, apoptotic/fibrotic processes, and cell calcium transport.
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Affiliation(s)
- Marharyta Semenikhina
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Daria V Lysikova
- Department of Physiology, Augusta University, Augusta, Georgia, United States
| | - Denisha R Spires
- Department of Physiology, Augusta University, Augusta, Georgia, United States
| | - Mark Domondon
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Krisztian Stadler
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Daria V Ilatovskaya
- Department of Physiology, Augusta University, Augusta, Georgia, United States
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2
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Meliambro K, Yang Y, de Cos M, Rodriguez Ballestas E, Malkin C, Haydak J, Lee JR, Salem F, Mariani LH, Gordon RE, Basgen JM, Wen HH, Fu J, Azeloglu EU, He JC, Wong JS, Campbell KN. KIBRA upregulation increases susceptibility to podocyte injury and glomerular disease progression. JCI Insight 2023; 8:e165002. [PMID: 36853804 PMCID: PMC10132156 DOI: 10.1172/jci.insight.165002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 02/21/2023] [Indexed: 03/01/2023] Open
Abstract
Despite recent progress in the identification of mediators of podocyte injury, mechanisms underlying podocyte loss remain poorly understood, and cell-specific therapy is lacking. We previously reported that kidney and brain expressed protein (KIBRA), encoded by WWC1, promotes podocyte injury in vitro through activation of the Hippo signaling pathway. KIBRA expression is increased in the glomeruli of patients with focal segmental glomerulosclerosis, and KIBRA depletion in vivo is protective against acute podocyte injury. Here, we tested the consequences of transgenic podocyte-specific WWC1 expression in immortalized human podocytes and in mice, and we explored the association between glomerular WWC1 expression and glomerular disease progression. We found that KIBRA overexpression in immortalized human podocytes promoted cytoplasmic localization of Yes-associated protein (YAP), induced actin cytoskeletal reorganization, and altered focal adhesion expression and morphology. WWC1-transgenic (KIBRA-overexpressing) mice were more susceptible to acute and chronic glomerular injury, with evidence of YAP inhibition in vivo. Of clinical relevance, glomerular WWC1 expression negatively correlated with renal survival among patients with primary glomerular diseases. These findings highlight the importance of KIBRA/YAP signaling to the regulation of podocyte structural integrity and identify KIBRA-mediated injury as a potential target for podocyte-specific therapy in glomerular disease.
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Affiliation(s)
- Kristin Meliambro
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Yanfeng Yang
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Marina de Cos
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | | | - Caroline Malkin
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jonathan Haydak
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - John R. Lee
- Division of Nephrology and Hypertension, Department of Medicine, Weill Cornell Medicine, New York, New York, USA
| | - Fadi Salem
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Jacksonville, Florida, USA
| | - Laura H. Mariani
- Division of Nephrology, Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Ronald E. Gordon
- Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - John M. Basgen
- Stereology and Morphometry Laboratory, Charles R. Drew University of Medicine and Science, Los Angeles, California, USA
| | - Huei Hsun Wen
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jia Fu
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Evren U. Azeloglu
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - John Cijiang He
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jenny S. Wong
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Kirk N. Campbell
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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3
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Yang Y, Shi W, Li C, Li L, Li J, Chen Y, Shi Q, Xie Z, Wang M, Zhang H, Zhao X, Chen Y, Li R, Liu S, Ye Z, Zhang L, Liang X. Growth associated protein 43 deficiency promotes podocyte injury by activating the calmodulin/calcineurin pathway under hyperglycemia. Biochem Biophys Res Commun 2023; 656:104-114. [PMID: 36963347 DOI: 10.1016/j.bbrc.2023.02.069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 02/17/2023] [Accepted: 02/24/2023] [Indexed: 03/13/2023]
Abstract
Podocyte injury is a crucial factor in the pathogenesis of diabetic kidney disease (DKD), and finding potential therapeutic interventions that can mitigate podocyte injury holds significant clinical relevance. This study was to elucidate the role of growth associated protein-43(Gap43) in podocyte injury of high glucose (HG). We confirmed the expression of Gap43 in human glomerulus and found that Gap43 expression was downregulated in podocytes of patients with DKD and HG-treated podocytes in vitro. Gap43 knockdown in podocytes promoted podocyte apoptosis, increased migration ability and decreased nephrin expression, while overexpression of Gap43 markedly suppressed HG-induced injury. Moreover, the increased expression and activity of calcineurin (CaN) were also abrogated by overexpression Gap43 in HG. Pretreatment with a typical CaN inhibitor FK506 in Gap43 knockdown podocytes restored the injury. Mechanistically, co-immunoprecipitation experiments suggested that Gap43 could bind to calmodulin (CaM). Pull-down assay further demonstrated that Gap43 and CaM directly interacts with each other via amino acids 30-52 of Gap43 and amino acids 133-197 of CaM. In addition, we also identified Pax5 as potential transcription inhibitor factor mediating Gap43 expression. In conclusion, the study indicated that the Gap43/CaM-CaN pathway may be exploited as a promising therapeutic target for protecting against podocyte injury in high glucose.
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Affiliation(s)
- Yan Yang
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China; Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Wanxin Shi
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Cuili Li
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China; School of Medicine, South China University of Technology, Guangzhou, 510006, China
| | - Luan Li
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China; School of Medicine, South China University of Technology, Guangzhou, 510006, China
| | - Jiaying Li
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China; Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Yingwen Chen
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China; School of Medicine, South China University of Technology, Guangzhou, 510006, China
| | - Qingying Shi
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China; Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Zhiyong Xie
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Mengjie Wang
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Hong Zhang
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Xingchen Zhao
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Yuanhan Chen
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Ruizhao Li
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Shuangxin Liu
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Zhiming Ye
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China
| | - Li Zhang
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China.
| | - Xinling Liang
- Department of Nephrology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, 510080, China; The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China.
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4
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Ahmadian E, Eftekhari A, Atakishizada S, Valiyeva M, Ardalan M, Khalilov R, Kavetskyy T. Podocytopathy: The role of actin cytoskeleton. Biomed Pharmacother 2022; 156:113920. [DOI: 10.1016/j.biopha.2022.113920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/12/2022] [Accepted: 10/24/2022] [Indexed: 11/02/2022] Open
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5
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Kim JH, Hwang KH, Dang BTN, Eom M, Kong ID, Gwack Y, Yu S, Gee HY, Birnbaumer L, Park KS, Cha SK. Insulin-activated store-operated Ca 2+ entry via Orai1 induces podocyte actin remodeling and causes proteinuria. Nat Commun 2021; 12:6537. [PMID: 34764278 PMCID: PMC8586150 DOI: 10.1038/s41467-021-26900-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 10/28/2021] [Indexed: 12/28/2022] Open
Abstract
Podocyte, the gatekeeper of the glomerular filtration barrier, is a primary target for growth factor and Ca2+ signaling whose perturbation leads to proteinuria. However, the effects of insulin action on store-operated Ca2+ entry (SOCE) in podocytes remain unknown. Here, we demonstrated that insulin stimulates SOCE by VAMP2-dependent Orai1 trafficking to the plasma membrane. Insulin-activated SOCE triggers actin remodeling and transepithelial albumin leakage via the Ca2+-calcineurin pathway in podocytes. Transgenic Orai1 overexpression in mice causes podocyte fusion and impaired glomerular filtration barrier. Conversely, podocyte-specific Orai1 deletion prevents insulin-stimulated SOCE, synaptopodin depletion, and proteinuria. Podocyte injury and albuminuria coincide with Orai1 upregulation at the hyperinsulinemic stage in diabetic (db/db) mice, which can be ameliorated by the suppression of Orai1-calcineurin signaling. Our results suggest that tightly balanced insulin action targeting podocyte Orai1 is critical for maintaining filter integrity, which provides novel perspectives on therapeutic strategies for proteinuric diseases, including diabetic nephropathy. Perturbations of Ca2+ signaling in podocytes may deteriorate kidney function and eventually lead to proteinuria. Here the authors show that insulin can affect the function of the calcium regulator Ora1 in podocytes, which is critical for maintaining kidney filter integrity.
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Affiliation(s)
- Ji-Hee Kim
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Kyu-Hee Hwang
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Bao T N Dang
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Minseob Eom
- Department of Pathology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - In Deok Kong
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Seyoung Yu
- Department of Pharmacology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Heon Yung Gee
- Department of Pharmacology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA.,Institute of Biomedical Research (BIOMED), School of Medical Sciences, Catholic University of Argentina, C1107AAZ, Buenos Aires, Argentina
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Seung-Kuy Cha
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea. .,Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea. .,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
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6
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Liu Z, Yoon J, Wichaidit C, Jaykumar AB, Dbouk HA, Embry AE, Liu L, Henderson JM, Chang AN, Cobb MH, Miller RT. Control of Podocyte and Glomerular Capillary Wall Structure and Elasticity by WNK1 Kinase. Front Cell Dev Biol 2021; 8:618898. [PMID: 33604334 PMCID: PMC7884762 DOI: 10.3389/fcell.2020.618898] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/31/2020] [Indexed: 11/25/2022] Open
Abstract
Cytoskeletal structure and its regulation are essential for maintenance of the differentiated state of specific types of cells and their adaptation to physiologic and pathophysiologic conditions. Renal glomerular capillaries, composed of podocytes, endothelial cells, and the glomerular basement membrane, have distinct structural and biophysical properties and are the site of injury in many glomerular diseases. Calcineurin inhibitors, immunosuppressant drugs used for organ transplantation and auto-immune diseases, can protect podocytes and glomerular capillaries from injury by preserving podocyte cytoskeletal structure. These drugs cause complications including hypertension and hyperkalemia which are mediated by WNK (With No Lysine) kinases as well as vasculopathy with glomerulopathy. WNK kinases and their target kinases oxidative stress-responsive kinase 1 (OSR1) and SPS1-related proline/alanine-rich kinase (SPAK) have fundamental roles in angiogenesis and are activated by calcineurin inhibitors, but the actions of these agents on kidney vasculature, and glomerular capillaries are not fully understood. We investigated WNK1 expression in cultured podocytes and isolated mouse glomerular capillaries to determine if WNK1 contributes to calcineurin inhibitor-induced preservation of podocyte and glomerular structure. WNK1 and OSR1/SPAK are expressed in podocytes, and in a pattern similar to podocyte synaptopodin in glomerular capillaries. Calcineurin inhibitors increased active OSR1/SPAK in glomerular capillaries, the Young’s modulus (E) of glomeruli, and the F/G actin ratio, effects all blocked by WNK inhibition. In glomeruli, WNK inhibition caused reduced and irregular synaptopodin-staining, abnormal capillary and foot process structures, and increased deformability. In cultured podocytes, FK506 activated OSR1/SPAK, increased lamellipodia, accelerated cell migration, and promoted traction force. These actions of FK506 were reduced by depletion of WNK1. Collectively, these results demonstrate the importance of WNK1 in regulation of the podocyte actin cytoskeleton, biophysical properties of glomerular capillaries, and slit diaphragm structure, all of which are essential to normal kidney function.
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Affiliation(s)
- Zhenan Liu
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Medicine Service, VA North Texas Health Care System, Dallas, TX, United States
| | - Joonho Yoon
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Medicine Service, VA North Texas Health Care System, Dallas, TX, United States
| | - Chonlarat Wichaidit
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Ankita B Jaykumar
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Hashem A Dbouk
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Addie E Embry
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Liping Liu
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Joel M Henderson
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, United States
| | - Audrey N Chang
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Medicine Service, VA North Texas Health Care System, Dallas, TX, United States
| | - Melanie H Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Richard Tyler Miller
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Medicine Service, VA North Texas Health Care System, Dallas, TX, United States
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7
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Struk T, Nair V, Eichinger F, Kretzler M, Wedlich-Söldner R, Bayraktar S, Pavenstädt H. Transcriptome analysis of primary podocytes reveals novel calcium regulated regulatory networks. FASEB J 2020; 34:14490-14506. [PMID: 32931033 DOI: 10.1096/fj.201902493rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 11/11/2022]
Abstract
Podocytes are pivotal in establishing the selective permeability of the glomerular filtration barrier. Recently, we showed that an increase of the intracellular calcium ion concentration [Ca2+ ] causes a rapid and transient actin reset (CaAR) measurable through live imaging microscopy using lifeact-mCherry as an actin dye in different cell types including the podocyte. This and other studies show the critical role [Ca2+ ] and the actin cytoskeleton play in podocyte homeostasis. To further investigate the role of [Ca2+ ] and the actin cytoskeleton in podocytes, we used a double fluorescent reporter mouse model to establish a primary podocyte culture system. We treated these podocytes temporarily with a Calcium Ionophore and facultatively with Latrunculin A, an inhibitor of actin polymerization. Unbiased genome wide transcriptional analysis identified a transcriptional response in podocytes to elevated [Ca2+ ] levels, affecting mRNA levels of PDGF-BB, RICTOR, and MIR17HG as mediators of Ca2+ -signaling. Comparison of the ex vivo transcriptional response from the primary podocyte culture with glomerular transcripts across a wide spectrum of CKD disease confirmed co-regulation of transcript sets, establishing the disease relevance of the model system. Our findings demonstrate novel [Ca2+ ] regulated gene networks in podocytes deepening our understanding of podocyte biology and disease.
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Affiliation(s)
- Thaddäus Struk
- Department of Medicine, University of Münster, Münster, Germany
| | - Viji Nair
- Michigan Kidney Translational Medical Core, University of Michigan, Ann Arbor, MI, USA
| | - Felix Eichinger
- Michigan Kidney Translational Medical Core, University of Michigan, Ann Arbor, MI, USA
| | - Matthias Kretzler
- Michigan Kidney Translational Medical Core, University of Michigan, Ann Arbor, MI, USA.,Internal Medicine, Department of Nephrology, University of Michigan, Ann Arbor, MI, USA
| | | | - Samet Bayraktar
- Department of Medicine, University of Münster, Münster, Germany
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8
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Wang Q, Tian X, Wang Y, Wang Y, Li J, Zhao T, Li P. Role of Transient Receptor Potential Canonical Channel 6 (TRPC6) in Diabetic Kidney Disease by Regulating Podocyte Actin Cytoskeleton Rearrangement. J Diabetes Res 2020; 2020:6897390. [PMID: 31998809 PMCID: PMC6964719 DOI: 10.1155/2020/6897390] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 12/17/2019] [Accepted: 12/23/2019] [Indexed: 01/19/2023] Open
Abstract
Podocyte injury is an important pathogenesis step causing proteinuric kidney diseases such as diabetic kidney disease (DKD). Actin cytoskeleton rearrangement in podocyte induced by multiple pathogenic factors is believed to be the key process resulting in glomerular injury. Many studies have recently shown that transient receptor potential canonical channel 6 (TRPC6) in podocyte plays a critical role in the development and progression of proteinuric kidney disease by regulating its actin cytoskeleton rearrangement. This review is aimed at summarizing the role of TRPC6 on DKD by regulating the podocyte actin cytoskeleton rearrangement, thereby help further broaden our views and understanding on the mechanism of DKD and provide a theoretic basis for exploring new therapeutic targets for DKD patients.
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Affiliation(s)
- Qian Wang
- Beijing Key Laboratory for Immune-Mediated Inflammatory Diseases, Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China
- Beijing University of Chinese Medicine, Beijing 100029, China
| | - Xuefei Tian
- Section of Nephrology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Yuyang Wang
- Department of Nephrology, Guang'anmen Hospital of China Academy of Traditional Chinese Medical Sciences, Beijing 100053, China
| | - Yan Wang
- Beijing Key Laboratory of Diabetes Research and Care, Center for Endocrine Metabolism and Immune Diseases, Luhe Hospital, Capital Medical University, Beijing 101149, China
| | - Jialin Li
- Beijing Key Laboratory for Immune-Mediated Inflammatory Diseases, Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China
- Beijing University of Chinese Medicine, Beijing 100029, China
| | - Tingting Zhao
- Beijing Key Laboratory for Immune-Mediated Inflammatory Diseases, Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China
| | - Ping Li
- Beijing Key Laboratory for Immune-Mediated Inflammatory Diseases, Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China
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9
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Tan RJ, Li Y, Rush BM, Cerqueira DM, Zhou D, Fu H, Ho J, Beer Stolz D, Liu Y. Tubular injury triggers podocyte dysfunction by β-catenin-driven release of MMP-7. JCI Insight 2019; 4:122399. [PMID: 31743113 DOI: 10.1172/jci.insight.122399] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 11/14/2019] [Indexed: 01/19/2023] Open
Abstract
Proteinuric chronic kidney disease (CKD) remains a major health problem worldwide. While it is well established that the progression of primary glomerular disease induces tubulointerstitial lesions, how tubular injury triggers glomerular damage is poorly understood. We hypothesized that injured tubules secrete mediators that adversely affect glomerular health. To test this, we used conditional knockout mice with tubule-specific ablation of β-catenin (Ksp-β-cat-/-) and subjected them to chronic angiotensin II (Ang II) infusion or Adriamycin. Compared with control mice, Ksp-β-cat-/- mice were dramatically protected from proteinuria and glomerular damage. MMP-7, a downstream target of β-catenin, was upregulated in treated control mice, but this induction was blunted in the Ksp-β-cat-/- littermates. Incubation of isolated glomeruli with MMP-7 ex vivo led to nephrin depletion and impaired glomerular permeability. Furthermore, MMP-7 specifically and directly degraded nephrin in cultured glomeruli or cell-free systems, and this effect was dependent on its proteolytic activity. In vivo, expression or infusion of exogenous MMP-7 caused proteinuria, and genetic ablation of MMP-7 protected mice from Ang II-induced proteinuria and glomerular injury. Collectively, these results demonstrate that β-catenin-driven MMP-7 release from renal tubules promotes glomerular injury via direct degradation of the key slit diaphragm protein nephrin.
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Affiliation(s)
| | | | | | - Débora Malta Cerqueira
- Division of Pediatric Nephrology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | | | - Haiyan Fu
- Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jacqueline Ho
- Division of Pediatric Nephrology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Donna Beer Stolz
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Youhua Liu
- Department of Pathology, and.,Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
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10
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Wang Y, Tao J, Wang M, Yang L, Ning F, Xin H, Xu X, Cai H, Zhang W, Yu K, Zhang X. Mechanism of Regulation of Big-Conductance Ca 2+-Activated K + Channels by mTOR Complex 2 in Podocytes. Front Physiol 2019; 10:167. [PMID: 30873046 PMCID: PMC6403181 DOI: 10.3389/fphys.2019.00167] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/12/2019] [Indexed: 12/12/2022] Open
Abstract
Podocytes, dynamic polarized cells wrapped around glomerular capillaries, are an essential component of the glomerular filtration barrier. BK channels consist of one of the slit diaphragm (SD) proteins in podocytes, interact with the actin cytoskeleton, and play vital roles in glomerular filtration. Mechanistic target of rapamycin (mTOR) complexes regulate expression of SD proteins, as well as cytoskeleton structure, in podocytes. However, whether mTOR complexes regulate podocyte BK channels is still unclear. Here, we investigated the mechanism of mTOR complex regulation of BK channels via real-time PCR, western blot, immunofluorescence, and patch clamping. Inhibiting mTORC1 with rapamycin or downregulating Raptor had no significant effect on BK channel mRNA and protein levels and bioactivity. However, the dual inhibitor of mTORC1 and mTORC2 AZD8055 and short hairpin RNA targeting Rictor downregulated BK channel mRNA and protein levels and bioactivity. In addition, MK2206, GF109203X, and GSK650394, which are inhibitors of Akt, PKCα, and SGK1, respectively, were employed to test the downstream signaling pathway of mTORC2. MK2206 and GF109203X had no effect on BK channel protein levels. MK2206 caused an obvious decrease in the current density of the BK channels. Moreover, GSK650394 downregulated the BK channel protein and mRNA levels. These results indicate mTORC2 not only regulates the distribution of BK channels through Akt, but also modulates BK channel protein expression via SGK1 in podocytes.
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Affiliation(s)
- Yinhang Wang
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Jie Tao
- Department of Nephrology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Mengling Wang
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Licai Yang
- Department of Nephrology, Minhang Hospital, Fudan University, Shanghai, China
| | - Fengling Ning
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Hong Xin
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Xudong Xu
- Department of Nephrology, Minhang Hospital, Fudan University, Shanghai, China
| | - Hui Cai
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States
- Section of Nephrology, Atlanta Veteran Administration Medical Center, Decatur, GA, United States
| | - Weiguang Zhang
- Department of Nephrology, Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, Beijing, China
- Beijing Key Laboratory of Kidney Disease, State Key Laboratory of Kidney Diseases, National Clinical Research Center of Kidney Diseases, Beijing, China
| | - Ker Yu
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Xuemei Zhang
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
- Department of Nephrology, Minhang Hospital, Fudan University, Shanghai, China
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11
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TRPC6 inactivation does not affect loss of renal function in nephrotoxic serum glomerulonephritis in rats, but reduces severity of glomerular lesions. Biochem Biophys Rep 2019; 17:139-150. [PMID: 30662960 PMCID: PMC6325086 DOI: 10.1016/j.bbrep.2018.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/06/2018] [Accepted: 12/16/2018] [Indexed: 12/26/2022] Open
Abstract
Canonical transient receptor potential-6 (TRPC6) channels have been implicated in a variety of chronic kidney diseases including familial and acquired forms of focal and segmental glomerulosclerosis (FSGS) and renal fibrosis following ureteral obstruction. Here we have examined the role of TRPC6 in progression of inflammation and fibrosis in the nephrotoxic serum (NTS) model of crescentic glomerulonephritis. This was assessed in rats with non-functional TRPC6 channels due to genomic disruption of an essential domain in TRPC6 channels (Trpc6del/del rats) and wild-type littermates (Trpc6wt/wt rats). Administration of NTS evoked albuminuria and proteinuria observed 4 and 28 days later that was equally severe in Trpc6wt/wt and Trpc6del/del rats. By 28 days, there were dense deposits of complement and IgG within glomeruli in both genotypes, accompanied by severe inflammation and fibrosis readily observed by standard histological methods, and also by increases in renal cortical expression of multiple markers (α-smooth muscle actin, vimentin, NLRP3, and CD68). Tubulointerstitial fibrosis appeared equally severe in Trpc6wt/wt and Trpc6del/del rats. TRPC6 inactivation did not protect against the substantial declines in renal function (increases in blood urea nitrogen, serum creatinine and kidney:body weight ratio) in NTS-treated animals, and increases in a urine maker of proximal tubule pathology (β2-macroglobulin) were actually more severe in Trpc6del/del animals. By contrast, glomerular pathology, blindly scored from histology, and from renal cortical expression of podocin suggested a partial but significant protective effect of TRPC6 inactivation within the glomerular compartment, at least during the autologous phase of the NTS model. TRPC6 inactivation in rats does not affect declines in overall renal function in an autoimmune model of rapidly progressing glomerulonephritis. TRPC6 inactivation does not reduce renal fibrosis or tubulointerstitial disease in autoimmune glomerulonephritis, and may exacerbate proximal tubule dysfunction in this model. TRPC6 inactivation reduces glomerulosclerosis and podocyte loss in autoimmune glomerulonephritis in rats.
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Key Words
- BUN, blood urea nitrogen
- CKD, chronic kidney disease
- Chronic kidney disease
- FSGS, focal and segmental glomerulosclerosis
- GBM, glomerular basement membrane
- Glomerulonephritis
- IL-1β, interleukin 1β
- NLRP3, NOD-like receptor pyrin domain containing-3 protein
- NTS, nephrotoxic serum
- PAN, puromycin amino nucleoside
- PAS, periodic acid-Schiff’s stain
- Renal fibrosis
- SMA, α-smooth muscle actin
- TCA, trichloroacetic acid
- TNF, tumor necrosis factor
- TRPC3, canonical transient receptor potential-3 channel
- TRPC5, canonical transient receptor potential-5 channel
- TRPC6
- TRPC6, canonical transient receptor potential-6 channel
- UUO, unilateral ureteral obstruction
- suPAR, soluble urokinase receptor
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12
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Embry AE, Liu Z, Henderson JM, Byfield FJ, Liu L, Yoon J, Wu Z, Cruz K, Moradi S, Gillombardo CB, Hussain RZ, Doelger R, Stuve O, Chang AN, Janmey PA, Bruggeman LA, Miller RT. Similar Biophysical Abnormalities in Glomeruli and Podocytes from Two Distinct Models. J Am Soc Nephrol 2018; 29:1501-1512. [PMID: 29572404 DOI: 10.1681/asn.2017050475] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 02/21/2018] [Indexed: 01/19/2023] Open
Abstract
Background FSGS is a pattern of podocyte injury that leads to loss of glomerular function. Podocytes support other podocytes and glomerular capillary structure, oppose hemodynamic forces, form the slit diaphragm, and have mechanical properties that permit these functions. However, the biophysical characteristics of glomeruli and podocytes in disease remain unclear.Methods Using microindentation, atomic force microscopy, immunofluorescence microscopy, quantitative RT-PCR, and a three-dimensional collagen gel contraction assay, we studied the biophysical and structural properties of glomeruli and podocytes in chronic (Tg26 mice [HIV protein expression]) and acute (protamine administration [cytoskeletal rearrangement]) models of podocyte injury.Results Compared with wild-type glomeruli, Tg26 glomeruli became progressively more deformable with disease progression, despite increased collagen content. Tg26 podocytes had disordered cytoskeletons, markedly abnormal focal adhesions, and weaker adhesion; they failed to respond to mechanical signals and exerted minimal traction force in three-dimensional collagen gels. Protamine treatment had similar but milder effects on glomeruli and podocytes.Conclusions Reduced structural integrity of Tg26 podocytes causes increased deformability of glomerular capillaries and limits the ability of capillaries to counter hemodynamic force, possibly leading to further podocyte injury. Loss of normal podocyte mechanical integrity could injure neighboring podocytes due to the absence of normal biophysical signals required for podocyte maintenance. The severe defects in podocyte mechanical behavior in the Tg26 model may explain why Tg26 glomeruli soften progressively, despite increased collagen deposition, and may be the basis for the rapid course of glomerular diseases associated with severe podocyte injury. In milder injury (protamine), similar processes occur but over a longer time.
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Affiliation(s)
- Addie E Embry
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Zhenan Liu
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joel M Henderson
- Department of Pathology, Boston University School of Medicine, Boston, Massachusetts
| | - F Jefferson Byfield
- Department of Physiology and Biophysics, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Liping Liu
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Medicine, Dallas Veterans Affairs Medical Center, Dallas, Texas
| | - Joonho Yoon
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Zhenzhen Wu
- Department of Medicine, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Katrina Cruz
- Department of Pathology, Boston University School of Medicine, Boston, Massachusetts
| | - Sara Moradi
- Department of Pathology, Boston University School of Medicine, Boston, Massachusetts
| | | | - Rihanna Z Hussain
- Department of Neurology, University of Texas Southwestern Medical School, Dallas, Texas; and
| | - Richard Doelger
- Department of Neurology, University of Texas Southwestern Medical School, Dallas, Texas; and
| | - Olaf Stuve
- Department of Neurology, University of Texas Southwestern Medical School, Dallas, Texas; and
| | - Audrey N Chang
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Paul A Janmey
- Department of Physiology and Biophysics, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Leslie A Bruggeman
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - R Tyler Miller
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas; .,Department of Medicine, Dallas Veterans Affairs Medical Center, Dallas, Texas
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13
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Saliba SW, Vieira ELM, Santos RPDM, Candelario-Jalil E, Fiebich BL, Vieira LB, Teixeira AL, de Oliveira ACP. Neuroprotective effects of intrastriatal injection of rapamycin in a mouse model of excitotoxicity induced by quinolinic acid. J Neuroinflammation 2017; 14:25. [PMID: 28143498 PMCID: PMC5282622 DOI: 10.1186/s12974-017-0793-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 01/06/2017] [Indexed: 12/19/2022] Open
Abstract
Background The mammalian target of rapamycin (mTOR) is a kinase involved in a variety of physiological and pathological functions. However, the exact role of mTOR in excitotoxicity is poorly understood. Here, we investigated the effects of mTOR inhibition with rapamycin against neurodegeneration, and motor impairment, as well as inflammatory profile caused by an excitotoxic stimulus. Methods A single and unilateral striatal injection of quinolinic acid (QA) was used to induce excitotoxicity in mice. Rapamycin (250 nL of 0.2, 2, or 20 μM; intrastriatal route) was administered 15 min before QA injection. Forty-eight hours after QA administration, rotarod test was performed to evaluate motor coordination and balance. Fluoro-Jade C, Iba-1, and GFAP staining were used to evaluate neuronal cell death, microglia morphology, and astrocytes density, respectively, at this time point. Levels of cytokines and neurotrophic factors were measured by ELISA and Cytometric Bead Array 8 h after QA injection. Striatal synaptosomes were used to evaluate the release of glutamate. Results We first demonstrated that rapamycin prevented the motor impairment induced by QA. Moreover, mTOR inhibition also reduced the neurodegeneration and the production of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α induced by excitotoxic stimulus. The lowest dose of rapamycin also increased the production of IL-10 and prevented the reduction of astrocyte density induced by QA. By using an in vitro approach, we demonstrated that rapamycin differently alters the release of glutamate from striatal synaptosomes induced by QA, reducing or enhancing the release of this neurotransmitter at low or high concentrations, respectively. Conclusion Taken together, these data demonstrated a protective effect of rapamycin against an excitotoxic stimulus. Therefore, this study provides new evidence of the detrimental role of mTOR in neurodegeneration, which might represent an important target for the treatment of neurodegenerative diseases. Electronic supplementary material The online version of this article (doi:10.1186/s12974-017-0793-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Soraya Wilke Saliba
- Department of Pharmacology, Universidade Federal de Minas Gerais, Avenida Antonio Carlos, 6627, 31270-901, Belo Horizonte, MG, Brazil.,Department of Psychiatry, University of Freiburg Medical School, Hauptstr. 5, 79104, Freiburg, Germany
| | | | - Rebeca Priscila de Melo Santos
- Department of Pharmacology, Universidade Federal de Minas Gerais, Avenida Antonio Carlos, 6627, 31270-901, Belo Horizonte, MG, Brazil
| | | | - Bernd L Fiebich
- Department of Psychiatry, University of Freiburg Medical School, Hauptstr. 5, 79104, Freiburg, Germany.
| | - Luciene Bruno Vieira
- Department of Pharmacology, Universidade Federal de Minas Gerais, Avenida Antonio Carlos, 6627, 31270-901, Belo Horizonte, MG, Brazil
| | - Antonio Lucio Teixeira
- Department of Internal Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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14
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Abstract
PURPOSE OF REVIEW In this review, we take a combined membrane biologist's and geneticist's view of the podocyte, to examine how genetics have informed our understanding of membrane receptors, channels, and other signaling molecules affecting podocyte health and disease. RECENT FINDINGS An integral part of the kidney, the glomerulus, is responsible for the kidney's filter function. Within the glomerulus, the podocyte is a unique cell serving a critically important role: it is exposed to signals from the urinary space in Bowman's capsule, it receives and transmits signals to/from the basement membrane upon which it elaborates, and it receives signals from the vascular space with which it also communicates, thus exposed to toxins, viruses, chemicals, proteins, and cellular components or debris that flow in the blood stream. Our understanding of how podocytes perform their important role has been largely informed by human genetics, and the recent revolution afforded by exome sequencing has brought a tremendous wealth of new genetic data to light. SUMMARY Genetically defined, rare/orphan podocytopathies, as reviewed here, are critically important to study as they may reveal the next generation targets for precision medicine in nephrology.
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15
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Buvall L, Wallentin H, Sieber J, Andreeva S, Choi HY, Mundel P, Greka A. Synaptopodin Is a Coincidence Detector of Tyrosine versus Serine/Threonine Phosphorylation for the Modulation of Rho Protein Crosstalk in Podocytes. J Am Soc Nephrol 2016; 28:837-851. [PMID: 27628902 DOI: 10.1681/asn.2016040414] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 07/29/2016] [Indexed: 12/25/2022] Open
Abstract
Tyrosine and serine/threonine signal-transduction pathways influence many aspects of cell behavior, including the spatial and temporal regulation of the actin cytoskeleton. However, little is known about how input from diverse tyrosine and serine/threonine kinases is integrated to control Rho protein crosstalk and actin remodeling, which are critically important in podocyte health and disease. Here we unveil the proteolytically-regulated, actin organizing protein synaptopodin as a coincidence detector of tyrosine versus serine/threonine phosphorylation. We show that serine/threonine and tyrosine kinases duel for synaptopodin stability versus degradation. EGFR/Src-mediated tyrosine phosphorylation of synaptopodin in podocytes promotes binding to the serine/threonine phosphatase calcineurin. This leads to the loss of 14-3-3 binding, resulting in synaptopodin degradation, Vav2 activation, enhanced Rac1 signaling, and ultimate loss of stress fibers. Our studies reveal how synaptopodin, a single proteolytically-controlled protein, integrates antagonistic tyrosine versus serine/threonine phosphorylation events for the dynamic control of the actin cytoskeleton in podocytes.
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Affiliation(s)
- Lisa Buvall
- Departments of Physiology, Institute of Neuroscience and Physiology, and
| | - Hanna Wallentin
- Clinical and Molecular Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Jonas Sieber
- Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts.,Kidney Disease Initiative, The Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Svetlana Andreeva
- Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Hoon Young Choi
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Peter Mundel
- and Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Anna Greka
- Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts; .,Kidney Disease Initiative, The Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
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16
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Roshanravan H, Kim EY, Dryer SE. 20-Hydroxyeicosatetraenoic Acid (20-HETE) Modulates Canonical Transient Receptor Potential-6 (TRPC6) Channels in Podocytes. Front Physiol 2016; 7:351. [PMID: 27630573 PMCID: PMC5005377 DOI: 10.3389/fphys.2016.00351] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/02/2016] [Indexed: 01/08/2023] Open
Abstract
The arachidonic acid metabolite 20-hydroxyeicosatetraenoic acid (20-HETE) regulates renal function, including changes in glomerular function evoked during tubuloglomerular feedback (TGF). This study describes the cellular actions of 20-HETE on cultured podocytes, assessed by whole-cell recordings from cultured podocytes combined with pharmacological and cell-biological manipulations of cells. Bath superfusion of 20-HETE activates cationic currents that are blocked by the pan-TRP blocker SKF-96365 and by 50 μM La3+, and which are attenuated after siRNA knockdown of TRPC6 subunits. Similar currents are evoked by a membrane-permeable analog of diacylgycerol (OAG), but OAG does not occlude responses to maximally-activating concentrations of 20-HETE (20 μM). Exposure to 20-HETE also increased steady-state surface abundance of TRPC6 subunits in podocytes as assessed by cell-surface biotinylation assays, and increased cytosolic concentrations of reactive oxygen species (ROS). TRPC6 activation by 20-HETE was eliminated in cells pretreated with TEMPOL, a membrane-permeable superoxide dismutase mimic. Activation of TRPC6 by 20-HETE was also blocked when whole-cell recording pipettes contained GDP-βS, indicating a role for either small or heterotrimeric G proteins in the transduction cascade. Responses to 20-HETE were eliminated by siRNA knockdown of podocin, a protein that organizes NADPH oxidase complexes with TRPC6 subunits in this cell type. In summary, modulation of ionic channels in podocytes may contribute to glomerular actions of 20-HETE.
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Affiliation(s)
- Hila Roshanravan
- Department of Biology and Biochemistry, University of Houston Houston, TX, USA
| | - Eun Y Kim
- Department of Biology and Biochemistry, University of Houston Houston, TX, USA
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of HoustonHouston, TX, USA; Division of Nephrology, Baylor College of MedicineHouston, TX, USA
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17
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Staffel J, Valletta D, Federlein A, Ehm K, Volkmann R, Füchsl AM, Witzgall R, Kuhn M, Schweda F. Natriuretic Peptide Receptor Guanylyl Cyclase-A in Podocytes is Renoprotective but Dispensable for Physiologic Renal Function. J Am Soc Nephrol 2016; 28:260-277. [PMID: 27153922 DOI: 10.1681/asn.2015070731] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 03/29/2016] [Indexed: 12/20/2022] Open
Abstract
The cardiac natriuretic peptides (NPs), atrial NP and B-type NP, regulate fluid homeostasis and arterial BP through renal actions involving increased GFR and vascular and tubular effects. Guanylyl cyclase-A (GC-A), the transmembrane cGMP-producing receptor shared by these peptides, is expressed in different renal cell types, including podocytes, where its function is unclear. To study the effects of NPs on podocytes, we generated mice with a podocyte-specific knockout of GC-A (Podo-GC-A KO). Despite the marked reduction of GC-A mRNA in GC-A KO podocytes to 1% of the control level, Podo-GC-A KO mice and control littermates did not differ in BP, GFR, or natriuresis under baseline conditions. Moreover, infusion of synthetic NPs similarly increased the GFR and renal perfusion in both genotypes. Administration of the mineralocorticoid deoxycorticosterone-acetate (DOCA) in combination with high salt intake induced arterial hypertension of similar magnitude in Podo-GC-A KO mice and controls. However, only Podo-GC-A KO mice developed massive albuminuria (controls: 35-fold; KO: 5400-fold versus baseline), hypoalbuminemia, reduced GFR, and marked glomerular damage. Furthermore, DOCA treatment led to decreased expression of the slit diaphragm-associated proteins podocin, nephrin, and synaptopodin and to enhanced transient receptor potential canonical 6 (TRPC6) channel expression and ATP-induced calcium influx in podocytes of Podo-GC-A KO mice. Concomitant treatment of Podo-GC-A KO mice with the TRPC channel blocker SKF96365 markedly ameliorated albuminuria and glomerular damage in response to DOCA. In conclusion, the physiologic effects of NPs on GFR and natriuresis do not involve podocytes. However, NP/GC-A/cGMP signaling protects podocyte integrity under pathologic conditions, most likely by suppression of TRPC channels.
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Affiliation(s)
| | | | | | | | | | | | - Ralph Witzgall
- Anatomy, University of Regensburg, Regensburg, Germany; and
| | - Michaela Kuhn
- Institute of Physiology, University of Würzburg, Würzburg, Germany
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18
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Wen Y, Wang Z, Liu L, Zhang Y, Zhou P, Liang J. Cabin1 localizes in glomerular podocyte and undergoes nuclear translocation during podocyte injury. Ren Fail 2015; 37:1344-8. [DOI: 10.3109/0886022x.2015.1073527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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19
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Wang L, Jirka G, Rosenberg PB, Buckley AF, Gomez JA, Fields TA, Winn MP, Spurney RF. Gq signaling causes glomerular injury by activating TRPC6. J Clin Invest 2015; 125:1913-26. [PMID: 25844902 DOI: 10.1172/jci76767] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 02/27/2015] [Indexed: 01/07/2023] Open
Abstract
Familial forms of focal segmental glomerulosclerosis (FSGS) have been linked to gain-of-function mutations in the gene encoding the transient receptor potential channel C6 (TRPC6). GPCRs coupled to Gq signaling activate TRPC6, suggesting that Gq-dependent TRPC6 activation underlies glomerular diseases. Here, we developed a murine model in which a constitutively active Gq α subunit (Gq(Q209L), referred to herein as GqQ>L) is specifically expressed in podocytes and examined the effects of this mutation in response to puromycin aminonucleoside (PAN) nephrosis. We found that compared with control animals, animals expressing GqQ>L exhibited robust albuminuria, structural features of FSGS, and reduced numbers of glomerular podocytes. Gq activation stimulated calcineurin (CN) activity, resulting in CN-dependent upregulation of TRPC6 in murine kidneys. Deletion of TRPC6 in GqQ>L-expressing mice prevented FSGS development and inhibited both tubular damage and podocyte loss induced by PAN nephrosis. Similarly, administration of the CN inhibitor FK506 reduced proteinuria and tubular injury but had more modest effects on glomerular pathology and podocyte numbers in animals with constitutive Gq activation. Moreover, these Gq-dependent effects on podocyte injury were generalizable to diabetic kidney disease, as expression of GqQ>L promoted albuminuria, mesangial expansion, and increased glomerular basement membrane width in diabetic mice. Together, these results suggest that targeting Gq/TRPC6 signaling may have therapeutic benefits for the treatment of glomerular diseases.
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MESH Headings
- Albuminuria/chemically induced
- Animals
- Calcineurin/metabolism
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/genetics
- Diabetic Nephropathies/genetics
- Diabetic Nephropathies/metabolism
- Diabetic Nephropathies/pathology
- GTP-Binding Protein alpha Subunits, Gq-G11/genetics
- GTP-Binding Protein alpha Subunits, Gq-G11/physiology
- Gene Deletion
- Genes, Reporter
- Glomerulosclerosis, Focal Segmental/chemically induced
- Glomerulosclerosis, Focal Segmental/genetics
- Glomerulosclerosis, Focal Segmental/pathology
- HEK293 Cells
- Humans
- Kidney Glomerulus/pathology
- Kidney Tubules/pathology
- Mice
- Mice, Mutant Strains
- Mice, Transgenic
- NFATC Transcription Factors/metabolism
- Podocytes/metabolism
- Point Mutation
- Puromycin Aminonucleoside/toxicity
- Recombinant Fusion Proteins/metabolism
- Signal Transduction
- TRPC Cation Channels/biosynthesis
- TRPC Cation Channels/deficiency
- TRPC Cation Channels/genetics
- TRPC Cation Channels/physiology
- TRPC6 Cation Channel
- Tacrolimus/pharmacology
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20
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Axelsson J, Rippe A, Rippe B. mTOR inhibition with temsirolimus causes acute increases in glomerular permeability, but inhibits the dynamic permeability actions of puromycin aminonucleoside. Am J Physiol Renal Physiol 2015; 308:F1056-64. [PMID: 25740597 DOI: 10.1152/ajprenal.00632.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 02/25/2015] [Indexed: 01/21/2023] Open
Abstract
Inhibitors of the mammalian target of rapamycin (mTORi) can produce de novo proteinuria in kidney transplant patients. On the other hand, mTORi has been shown to suppress disease progression in several animal models of kidney disease. In the present study, we investigated whether glomerular permeability can be acutely altered by the mTORi temsirolimus and whether mTORi can affect acute puromycin aminonucleoside (PAN) or angiotensin II (ANG II)-induced glomerular hyperpermeability. In anesthetized Wistar rats, the left ureter was cannulated for urine collection, while simultaneously blood access was achieved. Temsirolimus was administered as a single intravenous dose 30 min before the start of the experiments in animals infused with PAN or ANG II or in nonexposed animals. Polydispersed FITC-Ficoll-70/400 (molecular radius 10-80 Å) and (51)Cr-EDTA infusion was given during the whole experiment. Measurements of Ficoll in plasma and urine were performed sequentially before the temsirolimus injection (baseline) and at 5, 15, 30, 60, and 120 min after the start of the experiments. Urine and plasma samples were analyzed by high-performance size-exclusion chromatography (HPSEC) to assess glomerular sieving coefficients (θ) for Ficoll10-80Å. Temsirolimus per se increased baseline glomerular permeability to Ficoll50-80Å 45 min after its administration, a reactive oxygen species (ROS)-dependent phenomenon. PAN caused a rapid and reversible increase in glomerular permeability, peaking at 5 min, and again at 60-120 min, which could be blocked by the ROS scavenger tempol. mTORi abrogated the second permeability peak induced by PAN. However, it had no effect on the immediate ANG II- or PAN-induced increases in glomerular permeability.
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Affiliation(s)
| | - Anna Rippe
- Department of Nephrology, Lund University, Lund, Sweden
| | - Bengt Rippe
- Department of Nephrology, Lund University, Lund, Sweden
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21
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Sverrisson K, Axelsson J, Rippe A, Asgeirsson D, Rippe B. Dynamic, size-selective effects of protamine sulfate and hyaluronidase on the rat glomerular filtration barrier in vivo. Am J Physiol Renal Physiol 2014; 307:F1136-43. [PMID: 25209861 DOI: 10.1152/ajprenal.00181.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The proteinuric actions of protamine sulfate (PS) have classically been, at least partly, attributed to alterations of the negatively charged glomerular endothelial glycocalyx. To investigate whether the charge-selective properties of the glomerular filtration barrier (GFB) would be altered by PS, we assessed the glomerular sieving of conventional, uncharged, polydispersed Ficoll (n-Ficoll) compared with charge modified, conformationally intact, anionic (carboxymethylated) Ficoll (a-Ficoll) before and after systemic infusions of PS in rats. For comparison, we also investigated the impact of hyaluronidase (hyase), which partially degrades the glycocalyx, on GFB permeability. In anaesthetized Wistar rats, blood access was achieved, and the left ureter was cannulated for urine collection. Rats were infused with either n-Ficoll or a-Ficoll before and during systemic infusions with either PS or hyase. Plasma and urine samples were taken repeatedly and analyzed by high-performance size exclusion chromatography to assess glomerular sieving coefficients (θ) for Ficoll (radius 10-80 Å). The GFB showed a significant glomerular charge selectivity for Ficoll molecules of radius 20-35 Å. PS and hyase infusions reversibly increased θ for large Ficoll molecules (Ficoll molecules of radius 50-80 Å). Thus, for PS, θ for a-Ficoll molecules of radius 70 Å increased from 2.47 × 10(-5) ± 1.1(-5) to 7.25 × 10(-5) ± 1.1(-5) (P < 0.05) at 15 min. For hyase, changes in a-Ficoll molecules of radius 50-80 Å were, however, not statistically significant. Neither PS nor hyase had any effect on θ for n-Ficoll molecules of radius 20-45 Å or a-Ficoll molecules of radius 20-45 Å. It is concluded that systemically administered PS and hyase in moderate doses dynamically decreased the size selectivity of the rat GFB without affecting its charge selective properties.
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Affiliation(s)
| | | | - Anna Rippe
- Department of Nephrology, Lund University, Lund, Sweden
| | | | - Bengt Rippe
- Department of Nephrology, Lund University, Lund, Sweden
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Schlondorff J. How many Achilles' heels does a podocyte have? An update on podocyte biology: Table 1. Nephrol Dial Transplant 2014; 30:1091-7. [DOI: 10.1093/ndt/gfu214] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 05/07/2014] [Indexed: 11/15/2022] Open
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Conversion to sirolimus ameliorates cyclosporine-induced nephropathy in the rat: focus on serum, urine, gene, and protein renal expression biomarkers. BIOMED RESEARCH INTERNATIONAL 2014; 2014:576929. [PMID: 24971338 PMCID: PMC4055143 DOI: 10.1155/2014/576929] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 04/17/2014] [Indexed: 02/06/2023]
Abstract
Protocols of conversion from cyclosporin A (CsA) to sirolimus (SRL) have been widely used in immunotherapy after transplantation to prevent CsA-induced nephropathy, but the molecular mechanisms underlying these protocols remain nuclear. This study aimed to identify the molecular pathways and putative biomarkers of CsA-to-SRL conversion in a rat model. Four animal groups (n = 6) were tested during 9 weeks: control, CsA, SRL, and conversion (CsA for 3 weeks followed by SRL for 6 weeks). Classical and emergent serum, urinary, and kidney tissue (gene and protein expression) markers were assessed. Renal lesions were analyzed in hematoxylin and eosin, periodic acid-Schiff, and Masson's trichrome stains. SRL-treated rats presented proteinuria and NGAL (serum and urinary) as the best markers of renal impairment. Short CsA treatment presented slight or even absent kidney lesions and TGF-β, NF-κβ, mTOR, PCNA, TP53, KIM-1, and CTGF as relevant gene and protein changes. Prolonged CsA exposure aggravated renal damage, without clear changes on the traditional markers, but with changes in serums TGF-β and IL-7, TBARs clearance, and kidney TGF-β and mTOR. Conversion to SRL prevented CsA-induced renal damage evolution (absent/mild grade lesions), while NGAL (serum versus urine) seems to be a feasible biomarker of CsA replacement to SRL.
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Borsting E, Patel SV, Declèves AE, Lee SJ, Rahman QM, Akira S, Satriano J, Sharma K, Vallon V, Cunard R. Tribbles homolog 3 attenuates mammalian target of rapamycin complex-2 signaling and inflammation in the diabetic kidney. J Am Soc Nephrol 2014; 25:2067-78. [PMID: 24676635 DOI: 10.1681/asn.2013070811] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The endoplasmic reticulum (ER) stress response is activated in the diabetic kidney and functions to reduce ER protein accumulation and improve cellular function. We previously showed that tribbles homolog 3 (TRB3), an ER stress-associated protein, is upregulated in the diabetic kidney. Here, we investigated whether absence of TRB3 alters outcomes in diabetic nephropathy. Type 1 diabetes was induced in TRB3 wild-type and knockout ((-/-)) mice by low-dose streptozotocin, and the mice were followed for 12 weeks. Diabetic TRB3(-/-) mice developed higher levels of albuminuria and increased expression of inflammatory cytokine and chemokine mRNA in renal cortices relative to wild-type littermates, despite similar hyperglycemia. Diabetic TRB3(-/-) mice also expressed higher levels of ER stress-associated molecules in both the renal cortices and glomeruli. This change was associated with higher renal cortical phosphorylation of AKT at serine 473 (Ser(473)), which is the AKT site phosphorylated by mammalian target of rapamycin complex-2 (mTORC2). We show in renal tubular cells that TRB3 binds to mTOR and the rapamycin-insensitive companion of mTOR (Rictor), a protein specific to mTORC2. Finally, we demonstrate in murine tubular cells that TRB3 can inhibit secretion of IL-6. Thus, TRB3 reduces albuminuria and inflammatory gene expression in diabetic kidney disease by a mechanism that may involve inhibition of the mTORC2/AKT pathway and may prove to be a novel therapeutic target.
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Affiliation(s)
- Emily Borsting
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California
| | - Shalin V Patel
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California
| | - Anne-Emilie Declèves
- Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, La Jolla, California; and
| | - Sarah J Lee
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California
| | - Qazi M Rahman
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California
| | - Shizuo Akira
- Laboratory of Host Defense, WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Joe Satriano
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California; Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, La Jolla, California; and
| | - Kumar Sharma
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California; Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, La Jolla, California; and
| | - Volker Vallon
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California; Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, La Jolla, California; and
| | - Robyn Cunard
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, California; Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, La Jolla, California; and
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Spurney RF. Non-immunologic actions of calcineurin inhibitors in proteinuric kidney diseases. Front Endocrinol (Lausanne) 2014; 5:181. [PMID: 25429282 PMCID: PMC4228912 DOI: 10.3389/fendo.2014.00181] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Accepted: 10/07/2014] [Indexed: 11/13/2022] Open
Affiliation(s)
- Robert Frank Spurney
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, NC, USA
- *Correspondence:
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Schaldecker T, Kim S, Tarabanis C, Tian D, Hakroush S, Castonguay P, Ahn W, Wallentin H, Heid H, Hopkins CR, Lindsley CW, Riccio A, Buvall L, Weins A, Greka A. Inhibition of the TRPC5 ion channel protects the kidney filter. J Clin Invest 2013; 123:5298-309. [PMID: 24231357 DOI: 10.1172/jci71165] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/05/2013] [Indexed: 12/22/2022] Open
Abstract
An intact kidney filter is vital to retention of essential proteins in the blood and removal of waste from the body. Damage to the filtration barrier results in albumin loss in the urine, a hallmark of cardiovascular disease and kidney failure. Here we found that the ion channel TRPC5 mediates filtration barrier injury. Using Trpc5-KO mice, a small-molecule inhibitor of TRPC5, Ca2+ imaging in isolated kidney glomeruli, and live imagining of podocyte actin dynamics, we determined that loss of TRPC5 or its inhibition abrogates podocyte cytoskeletal remodeling. Inhibition or loss of TRPC5 prevented activation of the small GTP-binding protein Rac1 and stabilized synaptopodin. Importantly, genetic deletion or pharmacologic inhibition of TRPC5 protected mice from albuminuria. These data reveal that the Ca2+-permeable channel TRPC5 is an important determinant of albuminuria and identify TRPC5 inhibition as a therapeutic strategy for the prevention or treatment of proteinuric kidney disease.
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Mok KW, Mruk DD, Cheng CY. Regulation of blood-testis barrier (BTB) dynamics during spermatogenesis via the "Yin" and "Yang" effects of mammalian target of rapamycin complex 1 (mTORC1) and mTORC2. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 301:291-358. [PMID: 23317821 DOI: 10.1016/b978-0-12-407704-1.00006-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In mammalian testes, haploid spermatozoa are formed from diploid spermatogonia during spermatogenesis, which is a complicated cellular process. While these cellular events were reported in the 1960s and 1970s, the underlying molecular mechanism(s) that regulates these events remained unexplored until the past ∼10 years. For instance, adhesion proteins were shown to be integrated components at the Sertoli cell-cell interface and/or the Sertoli-spermatid interface in the late 1980s. But only until recently, studies have demonstrated that some of the adhesion proteins serve as the platform for signal transduction that regulates cell adhesion. In this chapter, a brief summary and critical discussion are provided on the latest findings regarding these cell-adhesion proteins in the testis and their relationship to spermatogenesis. Moreover, antagonistic effects of two mammalian target of rapamycin (mTOR) complexes, known as mTORC1 and mTORC2, on cell-adhesion function in the testis are discussed. Finally, a hypothetic model is presented to depict how these two mTOR-signaling complexes having the "yin" and "yang" antagonistic effects on the Sertoli cell tight junction (TJ)-permeability barrier can maintain the blood-testis barrier (BTB) integrity during the epithelial cycle while preleptotene spermatocytes are crossing the BTB.
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Affiliation(s)
- Ka Wai Mok
- Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, USA
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Abstract
Ca(2+)-mediated remodeling of the actin cytoskeleton is a dynamic process that regulates cell motility through the modulation of rho guanosine triphosphatase (GTPase) signaling. Kidney podocytes are unique, pericyte-like cells with a complex cellular organization consisting of a cell body, major processes, and foot processes (FPs). The FPs form a characteristic interdigitating pattern with FPs of neighboring podocytes, leaving in between filtration slits that are covered by the slit diaphragm (SD). The actin-based FP and the SD form the final barrier to proteinuria. Mutations affecting several podocyte proteins cause disruption of the filtration barrier and rearrangement of the highly dynamic podocyte actin cytoskeleton. Proteins regulating the plasticity of the podocyte actin cytoskeleton are therefore of critical importance for sustained kidney barrier function. Dynamic regulation of the actin-based contractile apparatus in podocyte FPs is essential for sustained kidney filter function. Thus, the podocyte represents an excellent model system to study calcium signaling and actin dynamics in a physiologic context. Here, we discuss the regulation of podocyte actin dynamics by angiotensin or bradykinin-mediated calcium influx and downstream Rho GTPase signaling pathways and how these pathways are operative in other cells including fibroblasts and cancer cells.
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Affiliation(s)
- Anna Greka
- Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Charlestown, MA 02129, USA.
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Wennmann DO, Hsu HH, Pavenstädt H. The renin-angiotensin-aldosterone system in podocytes. Semin Nephrol 2013; 32:377-84. [PMID: 22958492 DOI: 10.1016/j.semnephrol.2012.06.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The renin-angiotensin-aldosterone system (RAAS) plays a critical role in kidney function and its inhibition reduces proteinuria and preserves kidney function in patients with chronic kidney disease. Recent studies have shown that podocytes generate many components of the RAAS and they express receptors of RAAS, including angiotensin II, mineralocorticoid, and prorenin receptors. Crucial functions of podocytes, such as contraction, apoptosis, autophagocytosis, and cytoskeletal organization, have been shown to be regulated by the angiotensin II type 1 receptors. An activation of the glomerular RAAS and protection from podocyte injury by RAAS inhibitors have been shown in many glomerular diseases. Exploring the interaction between the local RAAS and the signaling involved in RAAS activation in podocytes will lead to new therapeutic strategies of podocyte protection.
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Affiliation(s)
- Dirk Oliver Wennmann
- Department of Internal Medicine D, University Hospital Münster, Münster, Germany
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Zhu L, Qi XY, Aoudjit L, Mouawad F, Baldwin C, Nattel S, Takano T. Nuclear factor of activated T cells mediates RhoA-induced fibronectin upregulation in glomerular podocytes. Am J Physiol Renal Physiol 2013; 304:F849-62. [PMID: 23389455 DOI: 10.1152/ajprenal.00495.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glomerulosclerosis is featured by accumulation of the extracellular matrixes in the glomerulus. We showed previously that activation of the small GTPase RhoA in podocytes induces heavy proteinuria and glomerulosclerosis in the mouse. In the current study, we investigated the mechanism by which RhoA stimulates the production of one of the extracellular matrixes, fibronectin, by podocytes, specifically testing the role of nuclear factor of activated T cells (NFAT). Expression of constitutively active RhoA in cultured podocytes activated the fibronectin promoter, upregulated fibronectin protein, and activated NFAT. Expression of constitutively active NFAT in podocytes also activated the fibronectin promoter and upregulated fibronectin protein. RhoA-induced NFAT activation and fibronectin upregulation were both dependent on the calcium/calmodulin pathway and Rho kinase. NFAT activation was also observed in vivo in the rat and mouse models of podocyte injury and proteinuria, and NFAT inhibition ameliorated fibronectin upregulation in the latter. RhoA activation induced a rise of intracellular calcium ion concentration ([Ca(2+)]i), which was at least in part dependent on the transient receptor potential canonical 6 (TRPC6) cation channel. The results indicate that RhoA activates NFAT by inducing a rise of [Ca(2+)]i in podocytes, which in turn contributes to fibronectin upregulation. This pathway may be responsible for the pathogenesis of certain glomerular diseases such as hypertension-mediated glomerulosclerosis.
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Affiliation(s)
- Lei Zhu
- Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
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Cunard R. Mammalian tribbles homologs at the crossroads of endoplasmic reticulum stress and Mammalian target of rapamycin pathways. SCIENTIFICA 2013; 2013:750871. [PMID: 24490110 PMCID: PMC3892554 DOI: 10.1155/2013/750871] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 11/20/2013] [Indexed: 05/03/2023]
Abstract
In 2000, investigators discovered Tribbles, a Drosophila protein that coordinates morphogenesis by inhibiting mitosis. Further work has delineated Xenopus (Xtrb2), Nematode (Nipi-3), and mammalian homologs of Drosophila tribbles, which include TRB1, TRB2, and TRB3. The sequences of tribbles homologs are highly conserved, and despite their protein kinase structure, to date they have not been shown to have kinase activity. TRB family members play a role in the differentiation of macrophages, lymphocytes, muscle cells, adipocytes, and osteoblasts. TRB isoforms also coordinate a number of critical cellular processes including glucose and lipid metabolism, inflammation, cellular stress, survival, apoptosis, and tumorigenesis. TRB family members modulate multiple complex signaling networks including mitogen activated protein kinase cascades, protein kinase B/AKT signaling, mammalian target of rapamycin, and inflammatory pathways. The following review will discuss metazoan homologs of Drosophila tribbles, their structure, expression patterns, and functions. In particular, we will focus on TRB3 function in the kidney in podocytes. This review will also discuss the key signaling pathways with which tribbles proteins interact and provide a rationale for developing novel therapeutics that exploit these interactions to provide better treatment options for both acute and chronic kidney disease.
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Affiliation(s)
- Robyn Cunard
- Research Service and Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, Mail Code 151, 3350 La Jolla Village Drive, San Diego, CA 92161, USA
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- *Robyn Cunard:
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Cheng XW, Shi GP, Kuzuya M, Sasaki T, Okumura K, Murohara T. Role for cysteine protease cathepsins in heart disease: focus on biology and mechanisms with clinical implication. Circulation 2012; 125:1551-62. [PMID: 22451605 DOI: 10.1161/circulationaha.111.066712] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Xian Wu Cheng
- Department of Cardiology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Nagoya, Japan.
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Is the antiproteinuric effect of cyclosporine a independent of its immunosuppressive function in T cells? Int J Nephrol 2012; 2012:809456. [PMID: 22778954 PMCID: PMC3384901 DOI: 10.1155/2012/809456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 04/20/2012] [Accepted: 05/03/2012] [Indexed: 12/21/2022] Open
Abstract
The antiproteinuric effect of cyclosporine A(CsA) has been believed to result from its immunosuppressive effect on the transcription factor NFAT in T cells. However, current evidences supporting this hypothesis are missing. A recent study showed that CsA has a direct antiproteinuric effect on podocytes, suggesting a novel non-immunosuppressive mechanism for CsA's antiproteinuric effect. Conditional NFATc1 activation in podoyctes per se is sufficient to induce proteinuria in mice, indicating that NFAT activation in podocytes is a critical pathogenic molecular event leading to podocyte injury and proteinuria. Meanwhile, evidence showed that TRPC6-mediated Ca(2+) influx stimulates NFAT-dependent TRPC6 expression. Altogether, these advances in podocyte research indicate that calcineurin-NFAT signal or calcineurin-synaptopodin axis has a direct proteinuric effect on podocytes which raises the possibility of developing specific antiproteinuric drugs that lack the unwanted effects of calcineurin or NFAT inhibition.
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Progress in pathogenesis of proteinuria. Int J Nephrol 2012; 2012:314251. [PMID: 22693670 PMCID: PMC3368192 DOI: 10.1155/2012/314251] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Revised: 03/24/2012] [Accepted: 03/26/2012] [Indexed: 02/06/2023] Open
Abstract
Aims. Proteinuria not only is a sign of kidney damage, but also is involved in the progression of renal diseases as an independent pathologic factor. Clinically, glomerular proteinuria is most commonly observed, which relates to structural and functional anomalies in the glomerular filtration barrier. The aim of this paper was to describe the pathogenesis of glomerular proteinuria. Data Sources. Articles on glomerular proteinuria retrieved from Pubmed and MEDLINE in the recent 5 years were reviewed. Results. The new understanding of the roles of glomerular endothelial cells and the glomerular basement membrane (GBM) in the pathogenesis of glomerular proteinuria was gained. The close relationships of slit diaphragm (SD) molecules such as nephrin, podocin, CD2-associated protein (CD2AP), a-actinin-4, transient receptor potential cation channel 6 (TRPC6), Densin and membrane-associated guanylate kinase inverted 1 (MAGI-1), α3β1 integrin, WT1, phospholipase C epsilon-1 (PLCE1), Lmx1b, and MYH9, and mitochondrial disorders and circulating factors in the pathogenesis of glomerular proteinuria were also gradually discovered. Conclusion. Renal proteinuria is a manifestation of glomerular filtration barrier dysfunction. Not only glomerular endothelial cells and GBM, but also the glomerular podocytes and their SDs play an important role in the pathogenesis of glomerular proteinuria.
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Ding WY, Saleem MA. Current concepts of the podocyte in nephrotic syndrome. Kidney Res Clin Pract 2012; 31:87-93. [PMID: 26889414 PMCID: PMC4715158 DOI: 10.1016/j.krcp.2012.04.323] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 04/09/2012] [Accepted: 04/12/2012] [Indexed: 01/08/2023] Open
Abstract
Nephrotic syndrome is a disorder of the glomerular filtration barrier, and central to the filtration mechanism of the glomerular filtration barrier is the podocyte. We are starting to better understand how this cell, with its unique architectural features, fulfils its exact filtration properties. The multiprotein complex between adjacent podocyte foot processes, the slit diaphragm, is essential to the control of the actin cytoskeleton and cell morphology. Many of the proteins within the slit diaphragm, including nephrin, podocin, transient receptor potential-6 channel, and α-actinin-4, have been identified via genetic studies of inherited nephrotic syndromes. Signaling from slit diaphragm proteins to the actin cytoskeleton is mediated via the Rho GTPases. These are thought to be involved in the control of podocyte motility, which has been postulated as a focus of proteinuric pathways. Nephrotic syndrome is currently treated with immunosuppressive therapy, with significant adverse effects. These therapies may work in nephrotic syndrome due to specific effects on the podocytes. This review aims to describe our current understanding of the cellular pathways and molecules within the podocyte relevant to nephrotic syndrome and its treatment. With our current knowledge of the cellular biology of the podocyte, there is much hope for targeted therapies for nephrotic syndromes.
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Affiliation(s)
- Wen Y Ding
- Academic Renal Unit, University of Bristol, Southmead Hospital, Bristol, UK
| | - Moin A Saleem
- Academic Renal Unit, University of Bristol, Southmead Hospital, Bristol, UK
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Abstract
As an integral member of the filtration barrier in the kidney glomerulus, the podocyte is in a unique geographical position: It is exposed to chemical signals from the urinary space (Bowman's capsule), it receives and transmits chemical and mechanical signals to/from the glomerular basement membrane upon which it elaborates, and it receives chemical and mechanical signals from the vascular space with which it also communicates. As with every cell, the ability of the podocyte to receive signals from the surrounding environment and to translate them to the intracellular milieu is dependent largely on molecules residing on the cell membrane. These molecules are the first-line soldiers in the ongoing battle to sense the environment, to respond to friendly signals, and to defend against injurious foes. In this review, we take a membrane biologist's view of the podocyte, examining the many membrane receptors, channels, and other signaling molecules that have been implicated in podocyte biology. Although we attempt to be comprehensive, our goal is not to capture every membrane-mediated pathway but rather to emphasize that this approach may be fruitful in understanding the podocyte and its unique properties.
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Affiliation(s)
- Anna Greka
- Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA.
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