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Abstract
The continuous accumulation of extracellular matrix will eventually lead to glomerular sclerosis, interstitial fibrosis, tubular atrophy and vascular sclerosis, which are involved in the progression of chronic kidney disease (CKD). If these processes can be discovered early and effective interventions given in time, the progression of kidney disease may be delayed. Therefore, exploring new biomarkers and therapeutic targets that can identify CKD at an early stage is urgently needed. In recent years, studies have shown that urine periostin may be used as a marker of early renal tubular injury. And in an animal model experiment of hypertensive nephropathy, periostin is involved in the progression of kidney injury and reflects its progression. Here we review the current progress on the role of periostin in pathologic pathways of kidney system to explore whether periostin is a potential therapeutic target for the treatment of CKD.
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Affiliation(s)
- Yuan-Yuan Jia
- Department of Health Management Medical Center, The Third Hospital of Jilin University, Changchun, China
| | - Yue Yu
- Department of Endocrinology and Metabolism, The Third Hospital of Jilin University, Changchun, China
| | - Hong-Jun Li
- Department of Health Management Medical Center, The Third Hospital of Jilin University, Changchun, China
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2
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Huang M, Zhu S, Huang H, He J, Tsuji K, Jin WW, Xie D, Ham O, Capen DE, Lu W, Păunescu TG, Yang B, Lu HAJ. Integrin-Linked Kinase Deficiency in Collecting Duct Principal Cell Promotes Necroptosis of Principal Cell and Contributes to Kidney Inflammation and Fibrosis. J Am Soc Nephrol 2019; 30:2073-2090. [PMID: 31653783 PMCID: PMC6830785 DOI: 10.1681/asn.2018111162] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 07/15/2019] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Necroptosis is a newly discovered cell death pathway that plays a critical role in AKI. The involvement of integrin-linked kinase (ILK) in necroptosis has not been studied. METHODS We performed experiments in mice with an Ilk deletion in collecting duct (CD) principal cells (PCs), and cultured tubular epithelial cells treated with an ILK inhibitor or ILK siRNA knockdown. RESULTS Ilk deletion in CD PCs resulted in acute tubular injury and early mortality in mice. Progressive interstitial fibrosis and inflammation associated with the activation of the canonical TGF-β signaling cascade were detected in the kidneys of the mice lacking ILK in the CD PCs. In contrast to the minimal apoptosis detected in the animals' injured CDs, widespread necroptosis was present in ILK-deficient PCs, characterized by cell swelling, deformed mitochondria, and rupture of plasma membrane. In addition, ILK deficiency resulted in increased expression and activation of necroptotic proteins MLKL and RIPK3, and membrane translocation of MLKL in CD PCs. ILK inhibition and siRNA knockdown reduced cell survival in cultured tubular cells, concomitant with increased membrane accumulation of MLKL and/or phospho-MLKL. Administration of a necroptosis inhibitor, necrostatin-1, blocked cell death in vitro and significantly attenuated inflammation, interstitial fibrosis, and renal failure in ILK-deficient mice. CONCLUSIONS The study demonstrates the critical involvement of ILK in necroptosis through modulation of the RIPK3 and MLKL pathway and highlights the contribution of CD PC injury to the development of inflammation and interstitial fibrosis of the kidney.
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Affiliation(s)
- Ming Huang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Shuai Zhu
- Department of Pharmacology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Huihui Huang
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jinzhao He
- Department of Pharmacology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Kenji Tsuji
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - William W Jin
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dongping Xie
- Department of Physiology, Tongji University School of Medicine, Shanghai, China; and
| | - Onju Ham
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Diane E Capen
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Weining Lu
- Renal Section, Departments of Medicine, and Pathology & Laboratory Medicine, Boston University Medical Center, Boston, Massachusetts
| | - Teodor G Păunescu
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Baoxue Yang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China;
| | - Hua A Jenny Lu
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts;
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Dai R, Liu H, Han X, Liu J, Zhai Y, Rao J, Shen Q, Xu H. Angiopoietin-like-3 knockout protects against glomerulosclerosis in murine adriamycin-induced nephropathy by attenuating podocyte loss. BMC Nephrol 2019; 20:185. [PMID: 31126248 PMCID: PMC6533758 DOI: 10.1186/s12882-019-1383-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Accepted: 05/13/2019] [Indexed: 12/19/2022] Open
Abstract
Background Angiopoietin-like-3 (Angptl3) knockout is known for its protective effects on podocyte injury and proteinuria in the early stage of adriamycin (ADR) nephropathy. The current study re-evaluated the renoprotective effect of Angptl3 knockout in chronic ADR nephropathy and attempted to explore the mechanism underlying the effect associated with Angptl3 knockout in glomerulosclerosis. Methods B6; 129S5 mice were injected with ADR to induce nephropathy. Kidney structure and serum and urine parameters were observed during long-term follow-up. Cultured primary mouse podocytes were exposed to ADR and analyzed for the expression of some relative proteins. Podocyte loss was analyzed in both in vivo and in vitro experiments. Results Angptl3 knockout attenuated proteinuria and hypoproteinemia, protected renal structure and function, and improved the survival of mice over the whole process of ADR nephropathy. Furthermore, Angptl3 knockout reduced the numbers of the detached and apoptotic cells in the renal tissue and alleviated podocyte loss in mice with ADR chronic nephropathy, thereby, delaying the glomerulosclerosis formation. Additional results in vitro showed that Angptl3 knockout attenuated ADR-induced primary podocyte loss, including podocyte detachment and apoptosis. Conclusion In addition to serving a renoprotective role in the early stage of ADR nephropathy, Angptl3 knockout contributed to disease amelioration throughout the ADR nephropathy process. Angptl3 knockout effectively delayed glomerulosclerosis formation by attenuating podocyte loss through rescuing podocytes from detachment and apoptosis. Angptl3 antagonists or inhibitors might have therapeutic potential in the occurrence and progression of nephropathy. Electronic supplementary material The online version of this article (10.1186/s12882-019-1383-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rufeng Dai
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, 201102, China.,Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China
| | - Haimei Liu
- Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China.,Department of Rheumatism, Children's Hospital of Fudan University, Shanghai, 201102, China
| | - Xinli Han
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, 201102, China.,Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China
| | - Junchao Liu
- Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China.,Department of Chinese Medicine, Children's Hospital of Fudan University, Shanghai, 201102, China
| | - Yihui Zhai
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, 201102, China.,Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China
| | - Jia Rao
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, 201102, China.,Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China
| | - Qian Shen
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, 201102, China.,Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China
| | - Hong Xu
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, 201102, China. .,Shanghai Kidney Development & Pediatric Kidney Disease Research Center, Shanghai, 201102, China.
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Lee MS, Tesh VL. Roles of Shiga Toxins in Immunopathology. Toxins (Basel) 2019; 11:E212. [PMID: 30970547 PMCID: PMC6521259 DOI: 10.3390/toxins11040212] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 12/20/2022] Open
Abstract
Shigella species and Shiga toxin-producing Escherichia coli (STEC) are agents of bloody diarrhea that may progress to potentially lethal complications such as diarrhea-associated hemolytic uremic syndrome (D+HUS) and neurological disorders. The bacteria share the ability to produce virulence factors called Shiga toxins (Stxs). Research over the past two decades has identified Stxs as multifunctional toxins capable of inducing cell stress responses in addition to their canonical ribotoxic function inhibiting protein synthesis. Notably, Stxs are not only potent inducers of cell death, but also activate innate immune responses that may lead to inflammation, and these effects may increase the severity of organ injury in patients infected with Stx-producing bacteria. In the intestines, kidneys, and central nervous system, excessive or uncontrolled host innate and cellular immune responses triggered by Stxs may result in sensitization of cells to toxin mediated damage, leading to immunopathology and increased morbidity and mortality in animal models (including primates) and human patients. Here, we review studies describing Stx-induced innate immune responses that may be associated with tissue damage, inflammation, and complement activation. We speculate on how these processes may contribute to immunopathological responses to the toxins.
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Affiliation(s)
- Moo-Seung Lee
- Environmental Diseases Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Daejeon 34141, Korea.
- Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology (UST), 127 Gajeong-ro, Yuseong-gu, Daejeon 34113, Korea.
| | - Vernon L Tesh
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77807, USA.
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Chronic kidney disease induced by an adenine rich diet upregulates integrin linked kinase (ILK) and its depletion prevents the disease progression. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1284-1297. [PMID: 30726718 DOI: 10.1016/j.bbadis.2019.01.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/21/2018] [Accepted: 01/23/2019] [Indexed: 01/06/2023]
Abstract
Kidney fibrosis is one of the main pathological findings of progressive chronic kidney disease (CKD) although the pathogenesis of renal scar formation remains incompletely explained. Integrin-linked kinase (ILK), a major scaffold protein between the extracellular matrix (ECM) and intracellular signaling pathways, is involved in several pathophysiological processes during renal damage. However, ILK contribution in the CKD progress remains to be fully elucidated. In the present work, we studied 1) the renal functional and structural consequences of CKD genesis and progression when ILK is depleted and 2) the potential of ILK depletion as a therapeutic approach to delay CKD progression. We induced an experimental CKD model, based on an adenine-supplemented diet on adult wild-type (WT) and ILK-depleted mice, with a tubulointerstitial damage profile resembling that is observed in human CKD. The adenine diet induced in WT mice a progressive increase in plasma creatinine and urea concentrations. In the renal cortex it was also observed tubular damage, interstitial fibrosis and progressive increased ECM components, pro-inflammatory and chemo-attractant cytokines, EMT markers and TGF-β1 expressions. These observations were highly correlated to a simultaneous increase of ILK expression and activity. In adenine-fed transgenic ILK-depleted mice, all these changes were prevented. Additionally, we evaluated the potential role of ILK depletion to be applied after the disease induction, as an effective approach to interventions in human CKD subjects. In this scenario, two weeks after the establishment of adenine-induced CKD, ILK was abrogated in WT mice and stabilized renal damage, avoiding CKD progression. We propose ILK to be a potential target to delay renal disease progression.
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He S, Liu X, Lin Z, Liu Y, Gu L, Zhou H, Tang W, Zuo J. Reversible SAHH inhibitor protects against glomerulonephritis in lupus-prone mice by downregulating renal α-actinin-4 expression and stabilizing integrin-cytoskeleton linkage. Arthritis Res Ther 2019; 21:40. [PMID: 30696480 PMCID: PMC6352376 DOI: 10.1186/s13075-019-1820-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 01/11/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Glomerulonephritis is one of the major complications and causes of death in systemic lupus erythematosus (SLE) and is characterized by glomerulosclerosis, interstitial fibrosis, and tubular atrophy, along with severe persistent proteinuria. DZ2002 is a reversible S-adenosyl-L-homocysteine hydrolase (SAHH) inhibitor with potent therapeutic activity against lupus nephritis in mice. However, the molecular events underlying the renal protective effects of DZ2002 remained unclear. This study is designed to uncover the molecular mechanisms of DZ2002 on glomerulonephritis of lupus-prone mice. METHODS We conducted a twice-daily treatment of DZ2002 on the lupus-prone NZB/WF1 mice, and the progression of lupus nephritis and alteration of renal function were monitored. The LC-MS-based label-free quantitative (LFQ) proteomic approach was applied to analyze the kidney tissue samples from the normal C57BL/6 mice and the NZB/WF1 mice treated with DZ2002 or vehicle. KEGG pathway enrichment and direct protein-protein interaction (PPI) network analyses were used to map the pathways in which the significantly changed proteins (SCPs) are involved. The selected proteins from proteomic analysis were validated by Western blot analysis and immunohistochemistry in the kidney tissues. RESULTS The twice-daily regimen of DZ2002 administration significantly ameliorated the lupus nephritis and improved the renal function in NZB/WF1 mice. A total of 3275 proteins were quantified, of which 253 proteins were significantly changed across normal C57BL/6 mice and the NZB/WF1 mice treated with DZ2002 or vehicle. Pathway analysis revealed that 13 SCPs were involved in tight junction and focal adhesion process. Further protein expression validation demonstrated that DZ2002-treated NZB/WF1 mice exhibited downregulation of α-actinin-4 and integrin-linked kinase (ILK), as well as the restoration of β1-integrin activation in the kidney tissues compared with the vehicle-treated ones. CONCLUSIONS Our study demonstrated the first evidence for the molecular mechanism of SAHH inhibitor on glomerulonephritis in SLE via the modulation of α-actinin-4 expression and focal adhesion-associated signaling proteins in the kidney.
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Affiliation(s)
- Shijun He
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Xing Liu
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Zemin Lin
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yuting Liu
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Lei Gu
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Hu Zhou
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China. .,Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
| | - Wei Tang
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China. .,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China.
| | - Jianping Zuo
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China. .,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China.
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Brittain AL, Basu R, Qian Y, Kopchick JJ. Growth Hormone and the Epithelial-to-Mesenchymal Transition. J Clin Endocrinol Metab 2017; 102:3662-3673. [PMID: 28938477 DOI: 10.1210/jc.2017-01000] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/31/2017] [Indexed: 02/07/2023]
Abstract
CONTEXT Previous studies have implicated growth hormone (GH) in the progression of several cancers, including breast, colorectal, and pancreatic. A mechanism by which GH may play this role in cancer is through the induction of the epithelial-to-mesenchymal transition (EMT). During the EMT process, epithelial cells lose their defining phenotypes, causing loss of cellular adhesion and increased cell migration. This review aims to carefully summarize the previous two decades of research that points to GH as an initiator of EMT, in both cancerous and noncancerous tissues. EVIDENCE ACQUISITION Sources were collected using PubMed and Google Scholar search engines by using specific GH- and/or EMT-related terms. Identified manuscripts were selected for further analysis based on presentation of GH-induced molecular markers of the EMT process in vivo or in vitro. EVIDENCE SYNTHESIS Cellular mechanisms involved in GH-induced EMT are the focus of this review, both in cancerous and noncancerous epithelial cells. CONCLUSIONS Our findings suggest that a myriad of molecular mechanisms are induced by GH that cause EMT and may point to potential therapeutic use of GH antagonists or any downregulator of GH action in EMT-related disease.
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Affiliation(s)
- Alison L Brittain
- Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701
- Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio 45701
| | - Reetobrata Basu
- Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701
| | - Yanrong Qian
- Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701
| | - John J Kopchick
- Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701
- Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio 45701
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Ying Q, Wu G. Molecular mechanisms involved in podocyte EMT and concomitant diabetic kidney diseases: an update. Ren Fail 2017; 39:474-483. [PMID: 28413908 PMCID: PMC6014344 DOI: 10.1080/0886022x.2017.1313164] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Epithelial–mesenchymal transition (EMT) is a tightly regulated process by which epithelial cells lose their hallmark epithelial characteristics and gain the features of mesenchymal cells. For podocytes, expression of nephrin, podocin, P-cadherin, and ZO-1 is downregulated, the slit diaphragm (SD) will be altered, and the actin cytoskeleton will be rearranged. Diabetes, especially hyperglycemia, has been demonstrated to incite podocyte EMT through several molecular mechanisms such as TGF-β/Smad classic pathway, Wnt/β-catenin signaling pathway, Integrins/integrin-linked kinase (ILK) signaling pathway, MAPKs signaling pathway, Jagged/Notch signaling pathway, and NF-κB signaling pathway. As one of the most fundamental prerequisites to develop ground-breaking therapeutic options to prevent the development and progression of diabetic kidney disease (DKD), a comprehensive understanding of the molecular mechanisms involved in the pathogenesis of podocyte EMT is compulsory. Therefore, the purpose of this paper is to update the research progress of these underlying signaling pathways and expound the podocyte EMT-related DKDs.
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Affiliation(s)
- Qidi Ying
- a Department of Pharmacology, Pharmacy , China Pharmaceutical University , Nanjing , Jiangsu , China
| | - Guanzhong Wu
- a Department of Pharmacology, Pharmacy , China Pharmaceutical University , Nanjing , Jiangsu , China
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Bai L, Huo B, Chen Z, Guo Q, Xu J, Fang J, Zhang J, Zhang F. Effect of Huayu Tongluo Herbs on Reduction of Proteinuria via Inhibition of Wnt/ β-Catenin Signaling Pathway in Diabetic Rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2017; 2017:3054145. [PMID: 28656052 PMCID: PMC5471573 DOI: 10.1155/2017/3054145] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/30/2017] [Indexed: 12/04/2022]
Abstract
The study investigated the expression of Wnt/β-catenin pathway in diabetic rats and the intervention effect of Huayu Tongluo herbs (HTH). Ten rats were randomly selected as control group and the remaining rats were established as diabetic models. The diabetic rats were randomly divided into model group and HTH treatment group. The intervention was intragastric administration in all rats for 20 weeks. At the end of every 4 weeks, fasting blood glucose and 24 h urinary total protein quantitatively were measured. At the end of the 20th week, biochemical parameters and body weight were tested. The kidney tissues were observed under light microscope and transmission electron microscopy. We examined Wnt/beta-catenin signaling pathway key proteins and renal interstitial fibrosis related molecular markers expression. The results showed that HTH could reduce urinary protein excretion and relieve renal pathological damage. Wnt4, p-GSK3β (S9), and β-catenin expression were decreased in the signaling pathway, but GSK3β level was not changed by HTH in diabetic rats. Furthermore, the expressions of TGF-β1 and ILK were decreased, but the level of E-cadherin was increased in diabetic rats after treatment with HTH. This study demonstrated that HTH could inhibit the high expression of Wnt/β-catenin pathway in kidney of diabetic rats. The effect might be one of the main ways to reduce urinary protein excretion.
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Affiliation(s)
- Lu Bai
- Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Beibei Huo
- Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Zhiqiang Chen
- Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Qian Guo
- Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Jing Xu
- Hebei University of Chinese Medicine, Shijiazhuang, Hebei 050200, China
| | - Jing Fang
- Hebei University of Chinese Medicine, Shijiazhuang, Hebei 050200, China
| | - Jianghua Zhang
- Hebei Medical University, Shijiazhuang, Hebei 050017, China
| | - Fenfang Zhang
- Affiliated Hospital of Hebei University of Traditional Chinese Medicine, Shijiazhuang, Hebei 050011, China
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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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Wang MX, Zhao XJ, Chen TY, Liu YL, Jiao RQ, Zhang JH, Ma CH, Liu JH, Pan Y, Kong LD. Nuciferine Alleviates Renal Injury by Inhibiting Inflammatory Responses in Fructose-Fed Rats. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:7899-7910. [PMID: 27718563 DOI: 10.1021/acs.jafc.6b03031] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Nuciferine is a major active component from the lotus leaf. This study examines the effects of nuciferine on fructose-induced renal injury and explores its possible mechanism. Rats consumed drinking water or 10% fructose for 12 weeks. Fructose-fed rats were orally treated with water or 7, 14, or 28 mg/kg of nuciferine for the last 6 weeks. HK-2 cells were exposed to 5 mM fructose alone or in combination with nuciferine (2.5-40 μM) for 24 h. Nuciferine significantly attenuated fructose-induced hyperuricemia, dyslipidemia, and systemic inflammation in rats. More importantly, it alleviated renal pathological injury with proteinuria at 20 and 40 mg/kg (2.58 ± 0.97 and 2.48 ± 1.04 mg/mg·creatinine, P < 0.05) compared with fructose-vehicle group (4.10 ± 1.18 mg/mg·creatinine). Furthermore, nuciferine reduced TLR4, MyD88, PI3K, ILK, p-AKT, p-P65, and NLRP3 inflammasome protein levels (P < 0.05 for all) in the renal cortex of fructose-fed rats (14 and 28 mg/kg) and fructose-exposed HK-2 cells (5-40 μM), which is consistent with its reduction of inflammatory cytokines IL-1β, IL-6, TNF-α, and MCP-1 (P < 0.05 for all) in vivo and in vitro. These findings suggest that nuciferine alleviated fructose-induced inflammation by inhibiting TLR4/PI3K/NF-κB signaling and NLRP3 inflammasome activation in rat renal cortex and HK-2 cells, which may contribute to the improvement of renal injury.
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Affiliation(s)
- Ming-Xing Wang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Xiao-Juan Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Tian-Yu Chen
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Yang-Liu Liu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Rui-Qing Jiao
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Jian-Hua Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Chun-Hua Ma
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Jia-Hui Liu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Ying Pan
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
| | - Ling-Dong Kong
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing 210023, People's Republic of China
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12
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Abstract
Genetic studies of hereditary forms of nephrotic syndrome have identified several proteins that are involved in regulating the permselective properties of the glomerular filtration system. Further extensive research has elucidated the complex molecular basis of the glomerular filtration barrier and clearly established the pivotal role of podocytes in the pathophysiology of glomerular diseases. Podocyte architecture is centred on focal adhesions and slit diaphragms - multiprotein signalling hubs that regulate cell morphology and function. A highly interconnected actin cytoskeleton enables podocytes to adapt in order to accommodate environmental changes and maintain an intact glomerular filtration barrier. Actin-based endocytosis has now emerged as a regulator of podocyte integrity, providing an impetus for understanding the precise mechanisms that underlie the steady-state control of focal adhesion and slit diaphragm components. This Review outlines the role of actin dynamics and endocytosis in podocyte biology, and discusses how molecular heterogeneity in glomerular disorders could be exploited to deliver more rational therapeutic interventions, paving the way for targeted medicine in nephrology.
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Abstract
Podocytes are highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule. When it comes to glomerular filtration, podocytes play an active role in preventing plasma proteins from entering the urinary ultrafiltrate by providing a barrier comprising filtration slits between foot processes, which in aggregate represent a dynamic network of cellular extensions. Foot processes interdigitate with foot processes from adjacent podocytes and form a network of narrow and rather uniform gaps. The fenestrated endothelial cells retain blood cells but permit passage of small solutes and an overlying basement membrane less permeable to macromolecules, in particular to albumin. The cytoskeletal dynamics and structural plasticity of podocytes as well as the signaling between each of these distinct layers are essential for an efficient glomerular filtration and thus for proper renal function. The genetic or acquired impairment of podocytes may lead to foot process effacement (podocyte fusion or retraction), a morphological hallmark of proteinuric renal diseases. Here, we briefly discuss aspects of a contemporary view of podocytes in glomerular filtration, the patterns of structural changes in podocytes associated with common glomerular diseases, and the current state of basic and clinical research.
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Affiliation(s)
- Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
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14
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Cano-Peñalver JL, Griera M, García-Jerez A, Hatem-Vaquero M, Ruiz-Torres MP, Rodríguez-Puyol D, Frutos SD, Rodríguez-Puyol M. Renal Integrin-Linked Kinase Depletion Induces Kidney cGMP-Axis Upregulation: Consequences on Basal and Acutely Damaged Renal Function. Mol Med 2015; 21:873-885. [PMID: 26562149 DOI: 10.2119/molmed.2015.00059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 11/09/2015] [Indexed: 12/12/2022] Open
Abstract
Soluble guanylyl cyclase (sGC) is activated by nitric oxide (NO) and produces cGMP, which activates cGMP-dependent protein kinases (PKG) and is hydrolyzed by specific phosphodiesterases (PDE). The vasodilatory and cytoprotective capacity of cGMP-axis activation results in a therapeutic strategy for several pathologies. Integrin-linked kinase (ILK), a major scaffold protein between the extracellular matrix and intracellular signaling pathways, may modulate the expression and functionality of the cGMP-axis-related proteins. We introduce ILK as a novel modulator in renal homeostasis as well as a potential target for cisplatin (CIS)-induced acute kidney injury (AKI) improvement. We used an adult mice model of depletion of ILK (cKD-ILK), which showed basal increase of sGC and PKG expressions and activities in renal cortex when compared with wildtype (WT) littermates. Twenty-four h activation of sGC activation with NO enhanced the filtration rate in cKD-ILK. During AKI, cKD-ILK maintained the cGMP-axis upregulation with consequent filtration rates enhancement and ameliorated CIS-dependent tubular epithelial-to-mesenchymal transition and inflammation and markers. To emphasize the role of cGMP-axis upregulation due to ILK depletion, we modulated the cGMP axis under AKI in vivo and in renal cultured cells. A suboptimal dose of the PDE inhibitor ZAP enhanced the beneficial effects of the ILK depletion in AKI mice. On the other hand, CIS increased contractility-related events in cultured glomerular mesangial cells and necrosis rates in cultured tubular cells; ILK depletion protected the cells while sGC blockade with ODQ fully recovered the damage.
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Affiliation(s)
- José Luis Cano-Peñalver
- Department of Systems Biology, Physiology Unit, Universidad de Alcalà, Alcalà de Henares, Madrid, Spain.,Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
| | - Mercedes Griera
- Department of Systems Biology, Physiology Unit, Universidad de Alcalà, Alcalà de Henares, Madrid, Spain.,Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
| | - Andrea García-Jerez
- Department of Systems Biology, Physiology Unit, Universidad de Alcalà, Alcalà de Henares, Madrid, Spain.,Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
| | - Marco Hatem-Vaquero
- Department of Systems Biology, Physiology Unit, Universidad de Alcalà, Alcalà de Henares, Madrid, Spain.,Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
| | - María Piedad Ruiz-Torres
- Department of Systems Biology, Physiology Unit, Universidad de Alcalà, Alcalà de Henares, Madrid, Spain.,Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
| | - Diego Rodríguez-Puyol
- Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain.,Biomedical Research Foundation and Nephrology Department, Hospital Príncipe de Asturias, Alcalà de Henares, Madrid, Spain
| | - Sergio de Frutos
- Department of Systems Biology, Physiology Unit, Universidad de Alcalà, Alcalà de Henares, Madrid, Spain.,Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
| | - Manuel Rodríguez-Puyol
- Department of Systems Biology, Physiology Unit, Universidad de Alcalà, Alcalà de Henares, Madrid, Spain.,Instituto Reina Sofia de Investigaciόn Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
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15
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Dai R, Lin Y, Liu H, Rao J, Zhai Y, Zha X, Fang X, Xu H. A vital role for Angptl3 in the PAN-induced podocyte loss by affecting detachment and apoptosis in vitro. BMC Nephrol 2015; 16:38. [PMID: 25884163 PMCID: PMC4383073 DOI: 10.1186/s12882-015-0034-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 03/17/2015] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Podocyte detachment and apoptosis are two risk factors causing podocyte loss, F-actin rearrangement is involved in detachment and apoptosis. However, the nature of events that promote detachment and apoptosis of podocytes and whether detachment occurred simultaneously with apoptosis are still unclear. Previously, it was found that angiopoietin-like3 (Angptl3) induces F-actin rearrangement in podocytes. In this study we investigate whether Angptl3 influences podocyte loss (detachment and apoptosis) and the process through which Angptl3 exactly influenced the podocyte loss. METHODS In conditionally immortalized mice podocytes, recombinant mice Angptl3 protein (rm-Angptl3) was used to mimic Angptl3 overexpression model and transfection with small interfering RNA (siRNA) to knockdown the expression of Angptl3. Both flow cytometry analysis and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay were used to detect apoptosis. Rearrangement of F-actin was assessed using confocal microscopy. Western blot assay was used to measure levels of Angptl3, integrin α3β1, integrin-linked kinase (ILK), p53, caspase 3, and phosphorylation of integrin β1. RESULTS In a puromycin aminonucleoside (PAN)-induced podocyte injury model, rm-Angptl3 accelerated the loss of podocytes, both detachment and apoptosis occurred, and F-actin rearrangement is involved in the process. However, knockdown of Angptl3 by siRNA markedly ameliorated these injuries. Observed effects were partially correlated with the altered integrin α3β1, ILK and p53, rather than caspase 3. CONCLUSIONS Angptl3 is a novel factor involved in the PAN-induced podocyte loss by affecting detachment and apoptosis in vitro. This study helps to deepen the understanding of the mechanisms of podocyte loss and lays the foundation for developing a new successful therapy for podocyte injury via lower expression of Angptl3.
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Affiliation(s)
- Rufeng Dai
- Department of Nephrology and Rheumatism, Children's Hospital of Fudan University, Shanghai, 201102, China.
| | - Yi Lin
- Department of Pediatrics, Affiliated Hospital of Qingdao University, Shandong, 266003, China.
| | - Haimei Liu
- Department of Nephrology and Rheumatism, Children's Hospital of Fudan University, Shanghai, 201102, China.
| | - Jia Rao
- Department of Nephrology and Rheumatism, Children's Hospital of Fudan University, Shanghai, 201102, China.
| | - Yihui Zhai
- Department of Nephrology and Rheumatism, Children's Hospital of Fudan University, Shanghai, 201102, China.
| | - Xiliang Zha
- Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai, 200032, China.
| | - Xiaoyan Fang
- Department of Nephrology and Rheumatism, Children's Hospital of Fudan University, Shanghai, 201102, China.
| | - Hong Xu
- Department of Nephrology and Rheumatism, Children's Hospital of Fudan University, Shanghai, 201102, China.
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16
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Saleem MA. One hundred ways to kill a podocyte. Nephrol Dial Transplant 2015; 30:1266-71. [PMID: 25637640 DOI: 10.1093/ndt/gfu363] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 10/27/2014] [Indexed: 12/30/2022] Open
Abstract
The podocyte is a highly specialized cell, forming within the developing glomerulus from a mesenchymal origin, acquiring some but not complete features of an epithelial cell as it matures. Once mature, this cell has the potential to receive signals from several different directions and sits within a dynamic microenvironment. By taking an overview of many lines of evidence, it is clear that we already know many signals that are tightly controlled in keeping the podocyte healthy. For example, vascular endothelial growth factor, insulin and integrins are all known to have bidirectional effects on podocyte functionality, depending on whether there is too much or too little. It is of little surprise therefore that disrupting this delicate balance can result in a dramatic loss of function, and manifestation of glomerular disease originating from many different primary insults. The cues directing podocyte phenotype and functionality for the purpose of this review will be divided into four main sources: (i) genetic, (ii) paracrine signals from endothelial and mesangial cells, (iii) direct contact signals to/from the glomerular basement membrane and (iv) signals from circulating plasma. Of course there are other influences, which we still know little about, such as flow and shear stresses, signals from the urinary space that should all be considered in the overall healthy environment.
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Affiliation(s)
- Moin A Saleem
- Bristol Children's Hospital, University of Bristol, Bristol, UK
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17
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LUO LINGRONG, LIU HONG, DONG ZHENG, SUN LIN, PENG YOUMING, LIU FUYOU. Small interfering RNA targeting ILK inhibits EMT in human peritoneal mesothelial cells through phosphorylation of GSK-3β. Mol Med Rep 2014; 10:137-44. [DOI: 10.3892/mmr.2014.2162] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 03/11/2014] [Indexed: 11/05/2022] Open
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18
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Locatelli M, Buelli S, Pezzotta A, Corna D, Perico L, Tomasoni S, Rottoli D, Rizzo P, Conti D, Thurman JM, Remuzzi G, Zoja C, Morigi M. Shiga toxin promotes podocyte injury in experimental hemolytic uremic syndrome via activation of the alternative pathway of complement. J Am Soc Nephrol 2014; 25:1786-98. [PMID: 24578132 DOI: 10.1681/asn.2013050450] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Shiga toxin (Stx)-producing Escherichia coli is the offending agent of postdiarrhea-associated hemolytic uremic syndrome (HUS), a disorder of glomerular ischemic damage and widespread microvascular thrombosis. We previously documented that Stx induces glomerular complement activation, generating C3a responsible for microvascular thrombosis in experimental HUS. Here, we show that the presence of C3 deposits on podocytes is associated with podocyte damage and loss in HUS mice generated by the coinjection of Stx2 and LPS. Because podocyte adhesion to the glomerular basement membrane is mediated by integrins, the relevance of integrin-linked kinase (ILK) signals in podocyte dysfunction was evaluated. Podocyte expression of ILK increased after the injection of Stx2/LPS and preceded the upregulation of Snail and downregulation of nephrin and α-actinin-4. Factor B deficiency or pretreatment with an inhibitory antibody to factor B protected mice against Stx2/LPS-induced podocyte dysregulation. Similarly, pretreatment with a C3a receptor antagonist limited podocyte loss and changes in ILK, Snail, and α-actinin-4 expression. In cultured podocytes, treatment with C3a reduced α-actinin-4 expression and promoted ILK-dependent nuclear expression of Snail and cell motility. These results suggest that Stx-induced activation of the alternative pathway of complement and generation of C3a promotes ILK signaling, leading to podocyte dysfunction and loss in Stx-HUS.
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Affiliation(s)
- Monica Locatelli
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Simona Buelli
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Anna Pezzotta
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Daniela Corna
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Luca Perico
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Susanna Tomasoni
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Daniela Rottoli
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Paola Rizzo
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Debora Conti
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Joshua M Thurman
- Division of Nephrology and Hypertension, University of Colorado Denver School of Medicine, Aurora, Colorado; and
| | - Giuseppe Remuzzi
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy; Unit of Nephrology and Dialysis, Azienda Ospedaliera Papa Giovanni XXIII, Bergamo, Italy
| | - Carlamaria Zoja
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy
| | - Marina Morigi
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy;
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19
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Lennon R, Randles MJ, Humphries MJ. The importance of podocyte adhesion for a healthy glomerulus. Front Endocrinol (Lausanne) 2014; 5:160. [PMID: 25352829 PMCID: PMC4196579 DOI: 10.3389/fendo.2014.00160] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/21/2014] [Indexed: 12/23/2022] Open
Abstract
Podocytes are specialized epithelial cells that cover the outer surfaces of glomerular capillaries. Unique cell junctions, known as slit diaphragms, which feature nephrin and Neph family proteins in addition to components of adherens, tight, and gap junctions, connect adjacent podocyte foot processes. Single gene disorders affecting the slit diaphragm result in nephrotic syndrome in humans, characterized by massive loss of protein across the capillary wall. In addition to specialized cell junctions, interconnecting podocytes also adhere to the glomerular basement membrane (GBM) of the capillary wall. The GBM is a dense network of secreted, extracellular matrix (ECM) components and contains tissue-restricted isoforms of collagen IV and laminin in addition to other structural proteins and ECM regulators such as proteases and growth factors. The specialized niche of the GBM provides a scaffold for endothelial cells and podocytes to support their unique functions and human genetic mutations in GBM components lead to renal failure, thus highlighting the importance of cell-matrix interactions in the glomerulus. Cells adhere to ECM via adhesion receptors, including integrins, syndecans, and dystroglycan and in particular the integrin heterodimer α3β1 is required to maintain barrier integrity. Therefore, the sophisticated function of glomerular filtration relies on podocyte adhesion both at cell junctions and at the interface with the ECM. In health, the podocyte coordinates signals from cell junctions and cell-matrix interactions, in response to environmental cues in order to regulate filtration and as our understanding of mechanisms that control cell adhesion in the glomerulus develops, then insight into the effects of disease will improve. The ultimate goal will be to develop targeted therapies to prevent or repair defects in the filtration barrier and to restore glomerular function.
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Affiliation(s)
- Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
- Department of Paediatric Nephrology, Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
- *Correspondence: Rachel Lennon, Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Michael Smith Building, Manchester M13 9PT, UK e-mail:
| | - Michael J. Randles
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
| | - Martin J. Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
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20
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A glimpse of the pathogenetic mechanisms of Wnt/β-catenin signaling in diabetic nephropathy. BIOMED RESEARCH INTERNATIONAL 2013; 2013:987064. [PMID: 24455745 PMCID: PMC3886614 DOI: 10.1155/2013/987064] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/22/2013] [Indexed: 01/22/2023]
Abstract
The Wnt family of proteins belongs to a group of secreted lipid-modified glycoproteins with highly conserved cysteine residues. Prior results indicate that Wnt/β-catenin signaling plays a prominent role in cell differentiation, adhesion, survival, and apoptosis and is involved in organ development, tumorigenesis, and tissue fibrosis, among other functions. Accumulating evidence has suggested that Wnt/β-catenin exhibits a pivotal function in the progression of diabetic nephropathy (DN). In this review, we focused on discussing the dual role of Wnt/β-catenin in apoptosis and epithelial mesenchymal transition (EMT) formation of mesangial cells. Moreover, we also elucidated the effect of Wnt/β-catenin in podocyte dysfunction, tubular EMT formation, and renal fibrosis under DN conditions. In addition, the molecular mechanisms involved in this process are introduced. This information provides a novel molecular target of Wnt/β-catenin for the protection of kidney damage and in delay of the progression of DN.
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21
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Sachs N, Sonnenberg A. Cell-matrix adhesion of podocytes in physiology and disease. Nat Rev Nephrol 2013; 9:200-10. [PMID: 23338211 DOI: 10.1038/nrneph.2012.291] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cell-matrix adhesion is crucial for maintaining the mechanical integrity of epithelial tissues. Podocytes--a key component of the glomerular filtration barrier--are exposed to permanent transcapillary filtration pressure and must therefore adhere tightly to the underlying glomerular basement membrane (GBM). The major cell-matrix adhesion receptor in podocytes is the integrin α3β1, which connects laminin 521 in the GBM through various adaptor proteins to the intracellular actin cytoskeleton. Other cell-matrix adhesion receptors expressed by podocytes include the integrins α2β1 and αvβ3, α-dystroglycan, syndecan-4 and type XVII collagen. Mutations in genes encoding any of the components critical for podocyte adhesion cause glomerular disease. This Review highlights recent advances in our understanding of the cell biology and genetics of podocyte adhesion with special emphasis on glomerular disease.
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Affiliation(s)
- Norman Sachs
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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22
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Upregulation of c-mip is closely related to podocyte dysfunction in membranous nephropathy. Kidney Int 2013; 83:414-25. [PMID: 23302718 DOI: 10.1038/ki.2012.426] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Membranous nephropathy is a glomerular disease typified by a nephrotic syndrome without infiltration of inflammatory cells or proliferation of resident cells. Although the cause of the disease is unknown, the primary pathology involves the generation of autoantibodies against antigen targets on the surface of podocytes. The mechanisms of nephrotic proteinuria, which reflect a profound podocyte dysfunction, remain unclear. We previously found a new gene, c-mip (c-maf-inducing protein), that was associated with the pathophysiology of idiopathic nephrotic syndrome. Here we found that c-mip was not detected in the glomeruli of rats with passive-type Heymann nephritis given a single dose of anti-megalin polyclonal antibody, yet immune complexes were readily present, but without triggering of proteinuria. Rats reinjected with anti-megalin develop heavy proteinuria a few days later, concomitant with c-mip overproduction in podocytes. This overexpression was associated with the downregulation of synaptopodin in patients with membranous nephropathy, rats with passive Heymann nephritis, and c-mip transgenic mice, while the abundance of death-associated protein kinase and integrin-linked kinase was increased. Cyclosporine treatment significantly reduced proteinuria in rats with passive Heymann nephritis, concomitant with downregulation of c-mip in podocytes. Thus, c-mip has an active role in the podocyte disorders of membranous nephropathy.
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Yadav A, Kumar D, Salhan D, Rattanavich R, Maheshwari S, Adabala M, Ding G, Singhal PC. Sirolimus modulates HIVAN phenotype through inhibition of epithelial mesenchymal transition. Exp Mol Pathol 2012; 93:173-81. [PMID: 22579465 DOI: 10.1016/j.yexmp.2012.04.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 04/26/2012] [Accepted: 04/26/2012] [Indexed: 10/28/2022]
Abstract
HIV-associated nephropathy (HIVAN) is characterized by proliferative phenotype in the form of collapsing glomerulopathy and microcystic dilatation of tubules. Recently, epithelial mesenchymal transition (EMT) of renal cells has been demonstrated to contribute to the pathogenesis of proliferative HIVAN phenotype. We hypothesized that sirolimus would modulate HIVAN phenotype by attenuating renal cell EMT. In the present study, we evaluated the effect of sirolimus on the development of renal cell EMT as well as on display of HIVAN phenotype in a mouse model of HIVAN (Tg26). Tg26 mice receiving normal saline (TgNS) showed enhanced proliferation of both glomerular and tubular cells when compared to control mice-receiving normal saline (CNS); on the other hand, Tg26 mice receiving sirolimus (TgS) showed attenuated renal cell proliferation when compared with TgNS. TgNS also showed increased number of α-SMA-, vimentin-, and FSP1-positive cells (glomerular as well as tubular) when compared with CNS; however, TgS showed reduced number of SMA, vimentin, and FSP1+ve renal cells when compared to TgNS. Interestingly, sirolimus preserved renal epithelial cell expression of E-cadherin in TgS. Since sirolimus attenuated renal cell ZEB expression (a repressor of E-cadherin transcription), it appears that sirolimus may be attenuating renal cell EMT by preserving epithelial cell E-cadherin expression.
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Affiliation(s)
- Anju Yadav
- Immunology Center, Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, NY 11030, United States
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24
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Zheng J, Gong J, Zhang A, Li S, Zeng Z, Han Y, Gan W. Attenuation of glomerular filtration barrier damage in adriamycin-induced nephropathic rats with bufalin: an antiproteinuric agent. J Steroid Biochem Mol Biol 2012; 129:107-14. [PMID: 22207085 DOI: 10.1016/j.jsbmb.2011.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Revised: 12/10/2011] [Accepted: 12/12/2011] [Indexed: 11/27/2022]
Abstract
Proteinuria is an important risk factor for the progression and prognosis of chronic kidney disease. Bufalin, a cardiotonic steroid, has been shown to posses a variety of biological activities including cardiotonic, anaesthetic and antineoplastic activities, and regulate the immune response. This study investigated the effects of bufalin against proteinuria and glomerular filtration barrier damage in rats with adriamycin (ADR)-induced nephropathy. We compared the blood and urine biochemical indices and the histologic and ultrastructure of the glomerulus in ADR rats with and without the intervention of bufalin or prednisone. The transcription, expression and distribution of the podocyte-associated molecules were compared utilising RT-PCR, western blotting and immunohistochemical staining. We found that bufalin reduced the urinary protein excretion and optimised the lipidaemia of the ADR rats. Bufalin alleviated the removal of podocyte foot processes and attenuated the changes in nephrin, podocin and integrin-linked kinase (ILK) stainings in the glomerulus of the ADR rats. Bufalin notably decreased the expression of nephrin and ILK but inhibited the down-regulation of podocin in protein levels on the renal cortex of the ADR rats. Additionally, bufalin inhibited the up-regulation of podocin and ILK in mRNA levels but did not affect nephrin mRNA levels. These results suggest that bufalin could alleviate ADR-induced proteinuria by protecting the glomerular filtration barrier and may be a novel potential therapeutic agent for proteinuria-associated kidney disease.
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Affiliation(s)
- Jun Zheng
- Department of Paediatric Nephrology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing 210003, PR China
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25
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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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26
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Abstract
Therapeutic off-target activities are well recognized for small-molecule drugs. In contrast, monoclonal antibodies (mAbs) traditionally are believed to act specifically and lack off-target therapeutic effects. In this issue of Science Translational Medicine, Fornoni et al. show therapeutic benefit, through an off-target-mediated mechanism, of the mAb drug rituximab in recurrent focal segmental glomerulosclerosis (FSGS) after kidney transplantation. These data shed new light on FSGS pathogenesis and suggest new therapeutic interventions for proteinuric diseases.
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Affiliation(s)
- Andrew C Chan
- Research Department, Genentech, South San Francisco, CA 94080, USA.
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27
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Sen K, Lindenmeyer MT, Gaspert A, Eichinger F, Neusser MA, Kretzler M, Segerer S, Cohen CD. Periostin is induced in glomerular injury and expressed de novo in interstitial renal fibrosis. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:1756-67. [PMID: 21854746 DOI: 10.1016/j.ajpath.2011.06.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 05/26/2011] [Accepted: 06/22/2011] [Indexed: 11/28/2022]
Abstract
Matricellular proteins participate in the pathogenesis of chronic kidney diseases. We analyzed glomerular gene expression profiles from patients with proteinuric diseases to identify matricellular proteins contributing to the progression of human nephropathies. Several genes encoding matricellular proteins, such as SPARC, THBS1, and CTGF, were induced in progressive nephropathies, but not in nonprogressive minimal-change disease. Periostin showed the highest induction, and its transcript levels correlated negatively with glomerular filtration rate in both glomerular and tubulointerstitial specimen. In well-preserved renal tissue, periostin localized to the glomerular tuft, the vascular pole, and along Bowman's capsule; no signal was detected in the tubulointerstitial compartment. Biopsies from patients with glomerulopathies and renal dysfunction showed enhanced periostin expression in the mesangium, tubular interstitium, and sites of fibrosis. Periostin staining correlated negatively with renal function. α-smooth muscle actin-positive mesangial and interstitial cells localized close to periostin-positive sites, as indicated by co-immunofluorescence. In vitro stimulation of mesangial cells by external addition of TGF-β1 resulted in robust induction of periostin. Addition of periostin to mesangial cells induced cell proliferation and decreased the number of cells expressing activated caspase-3, a marker of apoptosis. These human data indicate for the first time a role of periostin in glomerular and interstitial injury in acquired nephropathies.
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Affiliation(s)
- Kontheari Sen
- Institute of Physiology and Division of Nephrology, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Pereira RL, Buscariollo BN, Corrêa-Costa M, Semedo P, Oliveira CD, Reis VO, Maquigussa E, Araújo RC, Braga TT, Soares MF, Moura IC, Malheiros DMAC, Filho APS, Keller AC, Câmara NOS. Bradykinin receptor 1 activation exacerbates experimental focal and segmental glomerulosclerosis. Kidney Int 2011; 79:1217-27. [PMID: 21412216 DOI: 10.1038/ki.2011.14] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Focal and segmental glomerulosclerosis (FSGS) is one of the most important causes of end-stage renal failure. The bradykinin B1 receptor has been associated with tissue inflammation and renal fibrosis. To test for a role of the bradykinin B1 receptor in podocyte injury, we pharmacologically modulated its activity at different time points in an adriamycin-induced mouse model of FSGS. Estimated albuminuria and urinary protein to creatinine ratios correlated with podocytopathy. Adriamycin injection led to loss of body weight, proteinuria, and upregulation of B1 receptor mRNA. Early treatment with a B1 antagonist reduced albuminuria and glomerulosclerosis, and inhibited the adriamycin-induced downregulation of podocin, nephrin, and α-actinin-4 expression. Moreover, delayed treatment with antagonist also induced podocyte protection. Conversely, a B1 agonist aggravated renal dysfunction and even further suppressed the levels of podocyte-related molecules. Thus, we propose that kinin has a crucial role in the pathogenesis of FSGS operating through bradykinin B1 receptor signaling.
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Affiliation(s)
- Rafael L Pereira
- Departamento de Medicina, Laboratório de Imunologia Clínica e Experimental, Disciplina de Nefrologia, Universidade Federal de São Paulo, Brazil
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Kumar PA, Brosius FC, Menon RK. The glomerular podocyte as a target of growth hormone action: implications for the pathogenesis of diabetic nephropathy. Curr Diabetes Rev 2011; 7:50-5. [PMID: 21067510 PMCID: PMC4007067 DOI: 10.2174/157339911794273900] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 09/10/2010] [Indexed: 01/28/2023]
Abstract
Involvement of the growth hormone (GH) / insulin-like growth factor 1 (IGF-I) axis in the pathogenesis of diabetic nephropathy (DN) is strongly suggested by studies investigating the impact of GH excess and deficiency on renal structure and function. GH excess in both the human (acromegaly) and in transgenic animal models is characterized by significant structural and functional changes in the kidney. In the human a direct relationship has been noted between the activity of the GH/IGF-1 axis and renal hypertrophy, microalbuminuria, and glomerulosclerosis. Conversely, states of GH deficiency or deficiency or inhibition of GH receptor (GHR) activity confer a protective effect against DN. The glomerular podocyte plays a central and critical role in the structural and functional integrity of the glomerular filtration barrier and maintenance of normal renal function. Recent studies have revealed that the glomerular podocyte is a target of GH action and that GH's actions on the podocyte could be detrimental to the structure and function of the podocyte. These results provide a novel mechanism for GH's role in the pathogenesis of DN and offer the possibility of targeting the GH/IGF-1 axis for the prevention and treatment of DN.
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Affiliation(s)
- P Anil Kumar
- Pediatrics & Communicable Diseases, University of Michigan, Ann Arbor, MI 48109-0718, USA
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30
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Abstract
The sum of RNA transcripts of a cell, organ structure, or organism can be referred to as transcriptome. An increasing number of studies report on specific and common alterations in the renal transcriptome in human nephropathies. In this review several challenges in transcriptomic analyses of the human kidney are discussed. This includes ways to approach the heterogeneity of the kidney itself as well as the diversity of renal diseases. Conventional and upcoming techniques for transcriptional profiling of minute tissue samples are presented, including so-called next generation sequencing and microRNA detection. Different tools to integrate transcriptomic data in a systematic context are discussed beside the current challenge to combine such results with data sets from other integrative biology technologies.
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Affiliation(s)
- Jeffrey B Hodgin
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
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31
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Inhibition of integrin-linked kinase blocks podocyte epithelial-mesenchymal transition and ameliorates proteinuria. Kidney Int 2010; 78:363-73. [PMID: 20505657 DOI: 10.1038/ki.2010.137] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Proteinuria is a primary clinical symptom of a large number of glomerular diseases that progress to end-stage renal failure. Podocyte dysfunctions play a fundamental role in defective glomerular filtration in many common forms of proteinuric kidney disorders. Since binding of these cells to the basement membrane is mediated by integrins, we determined the role of integrin-linked kinase (ILK) in podocyte dysfunction and proteinuria. ILK expression was induced in mouse podocytes by various injurious stimuli known to cause proteinuria including TGF-beta1, adriamycin, puromycin, and high ambient glucose. Podocyte ILK was also found to be upregulated in human proteinuric glomerular diseases. Ectopic expression of ILK in podocytes decreased levels of the epithelial markers nephrin and ZO-1, induced mesenchymal markers such as desmin, fibronectin, matrix metalloproteinase-9 (MMP-9), and alpha-smooth muscle actin (alpha-SMA), promoted cell migration, and increased the paracellular albumin flux across podocyte monolayers. ILK also induced Snail, a key transcription factor mediating epithelial-mesenchymal transition (EMT). Blockade of ILK activity with a highly selective small molecule inhibitor reduced Snail induction and preserved podocyte phenotypes following TGF-beta1 or adriamycin stimulation. In vivo, this ILK inhibitor ameliorated albuminuria, repressed glomerular induction of MMP-9 and alpha-SMA, and preserved nephrin expression in murine adriamycin nephropathy. Our results show that upregulation of ILK is a convergent pathway leading to podocyte EMT, migration, and dysfunction. ILK may be an attractive target for therapeutic intervention of proteinuric kidney diseases.
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32
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Liu Y. New insights into epithelial-mesenchymal transition in kidney fibrosis. J Am Soc Nephrol 2009; 21:212-22. [PMID: 20019167 DOI: 10.1681/asn.2008121226] [Citation(s) in RCA: 669] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Epithelial-mesenchymal transition (EMT), a process by which differentiated epithelial cells undergo a phenotypic conversion that gives rise to the matrix-producing fibroblasts and myofibroblasts, is increasingly recognized as an integral part of tissue fibrogenesis after injury. However, the degree to which this process contributes to kidney fibrosis remains a matter of intense debate and is likely to be context-dependent. EMT is often preceded by and closely associated with chronic interstitial inflammation and could be an adaptive response of epithelial cells to a hostile or changing microenvironment. In addition to tubular epithelial cells, recent studies indicate that endothelial cells and glomerular podocytes may also undergo transition after injury. Phenotypic alteration of podocytes sets them in motion to functional impairment, resulting in proteinuria and glomerulosclerosis. Several intracellular signal transduction pathways such as TGFbeta/Smad, integrin-linked kinase (ILK) and Wnt/beta-catenin signaling are essential in controlling the process of EMT and presently are potential targets of antifibrotic therapy. This review highlights the current understanding of EMT and its underlying mechanisms to stimulate further discussion on its role, not only in the pathogenesis of renal interstitial fibrosis but also in the onset of podocyte dysfunction, proteinuria, and glomerulosclerosis.
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Affiliation(s)
- Youhua Liu
- Department of Pathology, University of Pittsburgh School of Medicine, S-405 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261, USA.
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33
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Abstract
Proteinuria is a major health-care problem that affects several hundred million people worldwide. Proteinuria is a cardinal sign and a prognostic marker of kidney disease, and also an independent risk factor for cardiovascular morbidity and mortality. Microalbuminuria is the earliest cue of renal complications of diabetes, obesity, and the metabolic syndrome. It can often progress to overt proteinuria that in 10-50% of patients is associated with the development of chronic kidney disease, ultimately requiring dialysis or transplantation. Therefore, reduction or prevention of proteinuria is highly desirable. Here we review recent novel insights into the pathogenesis and treatment of proteinuria, with a special emphasis on the emerging concept that proteinuria can result from enzymatic cleavage of essential regulators of podocyte actin dynamics by cytosolic cathepsin L (CatL), resulting in a motile podocyte phenotype. Finally, we describe signaling pathways controlling the podocyte actin cytoskeleton and motility and how these pathways can be manipulated for therapeutic benefit.
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Affiliation(s)
- Peter Mundel
- Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
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Li Y, Tan X, Dai C, Stolz DB, Wang D, Liu Y. Inhibition of integrin-linked kinase attenuates renal interstitial fibrosis. J Am Soc Nephrol 2009; 20:1907-18. [PMID: 19541809 DOI: 10.1681/asn.2008090930] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Integrin-linked kinase (ILK) is an intracellular serine/threonine protein kinase that regulates cell adhesion, survival, and epithelial-to-mesenchymal transition (EMT). In this study, we investigated the kinase activity of ILK during tubular EMT induced by TGF-beta1 and examined the therapeutic potential of an ILK inhibitor in obstructive nephropathy. TGF-beta1 induced a biphasic activation of ILK in renal tubular epithelial cells, with rapid activation starting at 5 min and the second wave of activation peaking at 24 h; the latter paralleled the induction of ILK protein expression. Pharmacologic inhibition of ILK with small-molecule inhibitor QLT-0267 abolished TGF-beta1-induced phosphorylation of Akt and glycogen synthase kinase-3beta, suppressed cyclin D1 expression, and largely restored the expression of E-cadherin and zonula occludens 1. Inhibition of ILK also blocked TGF-beta1-mediated induction of fibronectin, Snail1, plasminogen activator inhibitor 1, and matrix metalloproteinase 2. In a mouse model of obstructive nephropathy, administration of QLT-0267 inhibited beta-catenin accumulation; suppressed Snail1, alpha-smooth muscle actin, fibronectin, vimentin, and type I and type III collagen expression; and reduced total tissue collagen content. Inhibition of ILK did not affect kidney structure or function in normal mice. These findings suggest that increased ILK activity mediates EMT and the progression of renal fibrosis. Pharmacologic inhibition of ILK signaling may hold therapeutic potential for fibrotic kidney diseases.
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Affiliation(s)
- Yingjian Li
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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35
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Tesař V, Zima T. Recent Progress in the Pathogenesis of Nephrotic Proteinuria. Crit Rev Clin Lab Sci 2008; 45:139-220. [DOI: 10.1080/10408360801934865] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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36
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Chen J, Gui D, Chen Y, Mou L, Liu Y, Huang J. Astragaloside IV improves high glucose-induced podocyte adhesion dysfunction via alpha3beta1 integrin upregulation and integrin-linked kinase inhibition. Biochem Pharmacol 2008; 76:796-804. [PMID: 18652804 DOI: 10.1016/j.bcp.2008.06.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 06/23/2008] [Accepted: 06/23/2008] [Indexed: 01/15/2023]
Abstract
Impaired podocyte adhesion to glomerular basement membrane (GBM) may contribute to podocyte detachment from GBM, which represents a novel early mechanism leading to diabetic nephropathy (DN). Here, we examined the effects of Astragaloside IV (AS-IV), a saponin purified from Astragalus membranaceus (Fisch) Bge, on high glucose-induced cell adhesion dysfunction in cultured mouse podocytes. Cells were seeded into 96-well plates coated with basement membrane protein complex (BMC). The cells were incubated for 12h in media containing 30 mM glucose (HG) with 10, 50 and 100 microg/ml of AS-IV. The cells were also exposed to HG media with 100 microg/ml of AS-IV for 3, 6, 12 and 24h. Cell adhesion assays were performed by fluorescence and centrifugation methods, respectively. Levels of mRNA were determined by quantitative reverse transcriptase real-time PCR and protein expression was analyzed by immunoblotting. HG strongly inhibited adhesion of podocytes to BMC, accompanied by reduction in alpha(3)beta(1) integrin mRNA and protein expression, as well as increase in integrin-linked kinase (ILK) activity and expression. When podocytes under HG stimulation were treated with AS-IV, a dose- and time-dependent increase in cell-matrix adhesion was observed, which was significant from 10 microg/ml of AS-IV and from 6h of incubation of AS-IV with 100 microg/ml. This was accompanied by significant increases in alpha(3)beta(1) integrin mRNA and protein expression, as well as inhibition of ILK activation and overexpression. These results suggest that AS-IV improve HG-induced podocyte adhesion dysfunction, which is partly attributed to alpha(3)beta(1) integrin upregulation and ILK inhibition.
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Affiliation(s)
- Jianguo Chen
- Department of Nephrology, Zhejiang Hospital, 12 Lingyin Road, Hangzhou, Zhejiang Province, PR China
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37
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Hattori M, Akioka Y, Chikamoto H, Kobayashi N, Tsuchiya K, Shimizu M, Kagami S, Tsukaguchi H. Increase of integrin-linked kinase activity in cultured podocytes upon stimulation with plasma from patients with recurrent FSGS. Am J Transplant 2008; 8:1550-6. [PMID: 18557739 DOI: 10.1111/j.1600-6143.2008.02287.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Recurrent focal segmental glomerulosclerosis (FSGS) is a major challenge in the field of transplantation. Integrin-linked kinase (ILK) has emerged as a key mediator of podocyte-glomerular basement membrane (GBM) interactions. To clarify the involvement of plasma factors in FSGS recurrence, we examined the effects of plasma from FSGS patients with or without posttransplant recurrence on cultured podocytes, focusing particularly on ILK activity. Podocytes from a conditionally immortalized mouse podocyte cell line were treated with plasma from 11 FSGS patients, and ILK activity was determined using an immune complex kinase assay. Treatment with plasma from three patients with recurrence induced an increase in ILK activity. In contrast, no increase in ILK activity was observed in cultured podocytes treated with plasma from the remaining three patients with recurrence and five patients without recurrence. Cultured podocytes treated with plasma that induced ILK activity showed alterations of focal contact and detachment from the laminin matrix. In conclusion, this preliminary study provides experimental evidence suggesting the possible presence of circulating toxic factors in the plasma of some patients with recurrent FSGS, which induce an increase in podocyte ILK activity that may lead to the detachment of podocytes from the GBM.
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Affiliation(s)
- M Hattori
- Department of Pediatric Nephrology, Tokyo Women's Medical University, School of Medicine, Tokyo, Japan.
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38
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Shi X, Qu H, Kretzler M, Wu C. Roles of PINCH-2 in regulation of glomerular cell shape change and fibronectin matrix deposition. Am J Physiol Renal Physiol 2008; 295:F253-63. [PMID: 18480182 DOI: 10.1152/ajprenal.00070.2008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The PINCH-1-integrin-linked kinase (ILK)-alpha-parvin (PIP) complex plays important roles in the regulation of glomerular cell behavior, including podocyte shape change, apoptosis, and mesangial fibronectin matrix deposition. In this study, we show that PINCH-2, a protein that is structurally related to PINCH-1 but encoded by a different gene, is coexpressed with PINCH-1 in podocytes. Treatment of podocytes with transforming growth factor (TGF)-beta1 elevated the level of PINCH-2, resulting in increased association of PINCH-2 with ILK and alpha-parvin and concomitant displacement of PINCH-1 from the PIP complex. To gain insights into the functional consequences of elevated PINCH-2 expression, we overexpressed PINCH-2 in podocytes by infection with an adenovirus encoding PINCH-2. Overexpression of PINCH-2 resulted in displacement of PINCH-1 from the PIP complex and compromised podocyte spreading. The PINCH-2-mediated displacement of PINCH-1, however, did not prompt apoptosis. Interestingly, the effect of PINCH-2 on podocyte spreading depends on differentiation status, as overexpression of PINCH-2 in podocytes that were not fully differentiated did not alter cell spreading. Finally, we show that overexpression of PINCH-2 in mesangial cells resulted in displacement of PINCH-1 from the PIP complex but impaired neither mesangial cell spreading nor fibronectin matrix deposition. These studies suggest that PINCH-2 can substitute for PINCH-1 in at least certain processes in glomerular cells (e.g., podocyte survival signaling and mesangial fibronectin matrix deposition), albeit that an aberrantly high level of PINCH-2 may contribute to TGF-beta1-induced alteration in podocyte shape modulation.
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Affiliation(s)
- Xiaohua Shi
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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39
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Hu K, Wu C, Mars WM, Liu Y. Tissue-type plasminogen activator promotes murine myofibroblast activation through LDL receptor-related protein 1-mediated integrin signaling. J Clin Invest 2008; 117:3821-32. [PMID: 18037995 DOI: 10.1172/jci32301] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 09/19/2007] [Indexed: 12/16/2022] Open
Abstract
The activation of interstitial fibroblasts to become alpha-SMA-positive myofibroblasts is an essential step in the evolution of chronic kidney fibrosis, as myofibroblasts are responsible for the production and deposition of the ECM components that are a hallmark of the disease. Here we describe a signaling pathway that leads to this activation. Tissue-type plasminogen activator (tPA) promoted TGF-beta1-mediated alpha-SMA and type I collagen expression in rat kidney interstitial fibroblasts. This fibrogenic effect was independent of its protease activity but required its membrane receptor, the LDL receptor-related protein 1 (LRP-1). In rat kidney fibroblasts, tPA induced rapid LRP-1 tyrosine phosphorylation and enhanced beta1 integrin recruitment by facilitating the LRP-1/beta1 integrin complex formation. Blockade or knockdown of beta1 integrin abolished type I collagen and alpha-SMA expression. Furthermore, inhibition of the integrin-linked kinase (ILK), a downstream effector of beta1 integrin, or disruption of beta1 integrin/ILK engagement, abrogated the tPA action, whereas ectopic expression of ILK mimicked tPA in promoting myofibroblast activation. In murine renal interstitium after obstructive injury, tPA and alpha-SMA colocalized with LRP-1, and tPA deficiency reduced LRP-1/beta1 integrin interaction and myofibroblast activation. These findings show that tPA induces LRP-1 tyrosine phosphorylation, which in turn facilitates the LRP-1-mediated recruitment of beta1 integrin and downstream ILK signaling, thereby leading to myofibroblast activation. This study implicates tPA as a fibrogenic cytokine that promotes the progression of kidney fibrosis.
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Affiliation(s)
- Kebin Hu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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40
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Kimura M, Toyoda M, Kato M, Kobayashi K, Abe M, Kobayashi T, Miyauchi M, Yamamoto N, Umezono T, Suzuki D. Expression of alpha-actinin-4 in human diabetic nephropathy. Intern Med 2008; 47:1099-106. [PMID: 18552466 DOI: 10.2169/internalmedicine.47.0352] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Alpha-actinin-4 is an actin filament crosslinking protein that interacts with intercellular adhesion molecules. Recent animal studies suggested that alpha-actinin-4 is an essential component of the glomerular filtration barrier. However, little is known about its expression in human diabetic nephropathy (DN). METHODS Renal biopsy tissues were obtained from 17 patients with DN. We determined the mRNA and protein expression levels of alpha-actinin-4 by in situ hybridization and immunohistochemistry. The histopathological severity of DN was classified into two groups: mild and moderate mesangial expansion groups. We also measured urinary protein excretion and creatinine clearance. RESULTS Podocytes were positively stained for alpha-actinin-4 mRNA and protein. In the glomeruli, the percentage of cells positive for alpha-actinin-4 mRNA was significantly lower in moderate mesangial expansion group than in mild mesangial expansion group and control. The percentage of immunohistochemically positive area for alpha-actinin-4 protein in moderate mesangial expansion group was significantly lower than in mild mesangial expansion group and control. The percentage of cells positive for alpha-actinin-4 mRNA and area positive for the protein correlated inversely with severity of proteinuria. CONCLUSION Our results suggest that low expression levels of alpha-actinin-4 mRNA and protein are linked to the progression of glomerulopathy and proteinuria in human DN.
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Affiliation(s)
- Moritsugu Kimura
- Division of Nephrology and Metabolism, Department of Internal Medicine, Tokai University School of Medicine, Isehara
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Liu BC, Xia HL, Wu JN, Zhang XL, Liu DG, Gong YX. Influence of irbesartan on expression of ILK and its relationship with epithelial-mesenchymal transition in mice with unilateral ureteral obstruction. Acta Pharmacol Sin 2007; 28:1810-8. [PMID: 17959033 DOI: 10.1111/j.1745-7254.2007.00649.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
AIM Irbesartan, a new antagonist of the type 1 angiotensin II receptor, has been proven to be renal protective in both diabetic and non-diabetic nephropathy, but its exact mechanism is still uncertain. Here we investigated the influence of irbesartan on the expression of the integrin-linked kinase (ILK) and its relationship with epithelial-mesenchymal transition (EMT) in mice with unilateral ureteral obstruction (UUO). METHODS The mice were randomly divided into 3 groups: sham operation (C, n=20), UUO (n=40), and UUO with irbesartan treatment (UUO+irbesartan, n=40). Irbesartan was given at a dose of 50 mg/kg body weight per day by gavage. The experimental animals in the control group received the same volume of vehicle (0.9% saline solution). The animals were sacrificed at d 1, 3, 7, and 14, respectively, after the surgery. RESULTS The expression of the ILK at mRNA and protein levels were significantly increased in the UUO group 1 d after the surgery, which was significantly decreased by treatment with irbesartan (P<0.01, respectively). The expression of alpha-smooth muscle actin (alpha-SMA) was significantly increased, while E-cadherin was decreased in mice with UUO at d 3 after the surgery. Treatment with irbesartan significantly abrogated such effects (P<0.01). The immunohistochemistry analysis indicated that the protein expression of the ILK was positively correlated with alpha-SMA, but negatively with E-cadherin. CONCLUSION These results suggested that irbesartan attenuated renal tubulointerstitial fibrosis in UUO mice, which may be related to the inhibition of ILK expression, subsequently preventing the tubular EMT.
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Affiliation(s)
- Bi-cheng Liu
- Institute of Nephrology, Zhong Da Hospital, Southeast University, Nanjing 210009, China.
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Liu BC, Li MX, Zhang JD, Liu XC, Zhang XL, Phillips AO. Inhibition of integrin-linked kinase via a siRNA expression plasmid attenuates connective tissue growth factor-induced human proximal tubular epithelial cells to mesenchymal transition. Am J Nephrol 2007; 28:143-51. [PMID: 17951996 DOI: 10.1159/000110019] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Accepted: 08/24/2007] [Indexed: 12/14/2022]
Abstract
BACKGROUND Increasing evidence suggests that connective tissue growth factor (CTGF) is involved in the epithelial-to-mesenchymal transition (EMT). The exact intracellular events that drive this process, however, are not fully understood. In this study, we investigated the role of integrin-linked kinase (ILK) in mediating CTGF-induced EMT. METHODS The expression of alpha-smooth muscle actin (alpha-SMA) and E-cadherin upon the stimulation by recombinant human CTGF (rhCTGF) in cultured human tubular epithelial cell line (HK-2) was detected by real-time RT-PCR and Western blot. Subsequently, the role of ILK was determined by using ILK siRNA. RESULTS rhCTGF increased the mRNA expression of alpha-SMA significantly in a dose- and time-dependent manner, while E-cadherin mRNA decreased in a dose- and time-dependent manner. alpha-SMA protein was up-regulated after stimulation by 5 ng/ml CTGF for 96 h, and increased further after stimulation by 50 ng/ml. An immunocytochemical study showed that alpha-SMA was initially detectable at 48 h, and increased further at 72 h, while there was almost no alpha-SMA immunostaining observed in the control group at the same time point. E-cadherin protein was also down-regulated in a dose-dependent manner. Transfection of HK-2 cells with ILK-siRNA significantly attenuated rhCTGF-induced alpha-SMA induction and E-cadherin repression. CONCLUSION Our study suggested that ILK mediated the effect of EMT in proximal tubular epithelial cells stimulated by CTGF.
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Affiliation(s)
- Bi-Cheng Liu
- Institute of Nephrology, Zhong Da Hospital, Southeast University, Nanjing, PR China.
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Liu XC, Liu BC, Zhang XL, Li MX, Zhang JD. Role of ERK1/2 and PI3-K in the regulation of CTGF-induced ILK expression in HK-2 cells. Clin Chim Acta 2007; 382:89-94. [PMID: 17498677 DOI: 10.1016/j.cca.2007.03.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2007] [Revised: 03/28/2007] [Accepted: 03/28/2007] [Indexed: 12/21/2022]
Abstract
BACKGROUND Previous studies revealed that integrin-linked kinase (ILK), an intracellular serine/threonine protein kinase, is a critical mediator for tubular epithelial to mesenchymal transition (EMT), and likely plays an important role in the pathogenesis of chronic kidney fibrosis. However, the exact signal pathway has not been well understood. In this study, we investigated the role of extracellular regulating kinase 1/2 (ERK1/2) and phosphatidylinositol 3-kinase (PI3-K) in the regulation of ILK expression by connective tissue growth factor (CTGF) in HK-2 cells. METHODS Experiments were performed on transformed (human kidney cell (HKC)-clone 2) human proximal tubular epithelial cells (PTECs). Induction of ILK in response to CTGF was studied at the mRNA level by real-time PCR and protein by immunoblotting. Chemical inhibitors were used to assess the role of MEK/ERK1/2, PI3-K, and P38 MAPK signaling pathways in induction of ILK by CTGF. RESULTS CTGF induced ILK protein expression in HK-2 cells in a time- and dose-dependent manner. There was a 5.638-fold (control: 1.000+/-0.290, 50 ng/ml: 5.638+/-1.200; *P<0.05 vs. control) and 5.740-fold (0 h: 1.000+/-0.498, 48 h: 5.740+/-1.465, *P<0.05 vs. control) increase compared to control respectively. CTGF-induced ILK expression was partially reduced by inhibiting ERK1/2 and PI3-K activation. There was no influence of ILK expression by inhibiting P38 MAPK activation when cells treated with CTGF. CONCLUSION CTGF induces the expression of ILK protein in HK-2 cells. This induction is partially dependent on MEK/ERK1/2 and PI3-K signaling pathways. Inhibiting CTGF-induced ILK by targeting PI3-K and/or MEK/ERK1/2 signaling pathways could be of therapeutic value in renal fibrosis.
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Affiliation(s)
- Xiao-Cong Liu
- Institute of Nephrology, Zhong Da Hospital, Southeast University, Nanjing, China
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Abstract
The glomerular filtration barrier consists of the fenestrated endothelium, the glomerular basement membrane and the terminally differentiated visceral epithelial cells known as podocytes. It is now widely accepted that damage to, or originating within, the podocytes is a key event that initiates progression towards sclerosis in many glomerular diseases. A wide variety of strategies have been employed by investigators from many scientific disciplines to study the podocyte. Although invaluable insights have accrued from conventional approaches, including cell culture and biochemical-based methods, many renal researchers continue to rely upon the mouse to address the form and function of the podocyte. This review summarizes how genetic manipulation in the mouse has advanced our understanding of the podocyte in relation to the maintenance of the glomerular filtration barrier in health and disease.
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Affiliation(s)
- Jean-Louis R Michaud
- Kidney Research Centre and Molecular Medicine Program, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada
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Jung KY, Chen K, Kretzler M, Wu C. TGF-β1 Regulates the PINCH-1–Integrin-Linked Kinase–α-Parvin Complex in Glomerular Cells. J Am Soc Nephrol 2006; 18:66-73. [PMID: 17167118 DOI: 10.1681/asn.2006050421] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Glomerular damage is a major cause of renal failure. Recent studies suggest that a ternary protein complex that consists of PINCH-1, integrin-linked kinase, and alpha-parvin, cytoplasmic components of cell-extracellular matrix adhesions, plays pivotal roles in regulation of glomerular cell behavior. It is reported here that TGF-beta1, a key factor in the progression of glomerular failure, regulates the PINCH-1-integrin-linked kinase-alpha-parvin (PIP) complex formation in glomerular podocytes and mesangial cells. Treatment of podocytes with TGF-beta1 inhibited the PIP complex formation. Forced disruption of the PIP complex in podocytes activated p38 mitogen-activated protein kinase and promoted apoptosis. Importantly, inhibition of p38 mitogen-activated protein kinase, either with a chemical p38 inhibitor (SB202190) or with a dominant negative form of p38alpha, alleviates podocyte apoptosis that is induced by the disruption of the PIP complex. In contrast to an inhibitory role in podocytes, TGF-beta1 promotes the PIP complex formation in mesangial cells. Thus, TGF-beta1 regulates the PIP complex in a cell type-dependent manner. Because the PIP complex promotes glomerular mesangial matrix deposition and protects podocytes from apoptosis, the TGF-beta1-induced up- and downregulation of the PIP complex likely contribute to the pleiotropic effects of TGF-beta1 on different glomerular cell types and hence the progression of glomerular failure.
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Affiliation(s)
- Kyu Yong Jung
- Department of Pathology, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, PA 15261, USA
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Zoja C, Abbate M, Remuzzi G. Progression of chronic kidney disease: insights from animal models. Curr Opin Nephrol Hypertens 2006; 15:250-7. [PMID: 16609291 DOI: 10.1097/01.mnh.0000222691.53970.83] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
PURPOSE OF REVIEW Chronic kidney diseases are emerging as a worldwide public health problem. Clarification of the mechanisms underlying progression of proteinuric nephropathies received significant input from the generation of transgenic and knockout animals and from novel approaches to block mediators of injury. Reviewed here are advances in animal models used as a tool to address some relevant questions to the pathophysiology of human chronic nephropathies. RECENT FINDINGS Gene targeting in rodents identified podocyte loss as central event in the development of glomerulosclerosis. The trigger is dysfunction or absence of podocyte molecules that stabilize the slit diaphragm or anchor foot processes to the basement membrane. Sustained injury of the glomerular barrier to proteins is transmitted to the tubulointerstitial compartment leading to inflammation and fibrosis. Blocking NF-kappaB activity and chemokine signals in the kidney effectively interrupts such process. Growth factors produced by tubular cells and inflammatory cells contribute to interstitial fibrogenesis via myofibroblast activation. SUMMARY Development of genetically engineered animals and techniques to specifically manipulate cellular mediators has highlighted the determinants of glomerulosclerosis and tubulointerstitial injury. This knowledge will provide basis for novel interventions to protect the podocyte in chronic progressive glomerulopathies and to halt renal scarring and loss of function.
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Affiliation(s)
- Carla Zoja
- Mario Negri Institute for Pharmacological Research, Bergamo, Italy.
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Dai C, Stolz DB, Bastacky SI, St-Arnaud R, Wu C, Dedhar S, Liu Y. Essential Role of Integrin-Linked Kinase in Podocyte Biology: Bridging the Integrin and Slit Diaphragm Signaling. J Am Soc Nephrol 2006; 17:2164-75. [PMID: 16837631 DOI: 10.1681/asn.2006010033] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Integrin-linked kinase (ILK) has been implicated in the pathogenesis of proteinuria and congenital nephrotic syndrome. However, the function of ILK in glomerular podocyte in a physiologic setting remains unknown. In this study, a mouse model was generated in which ILK gene was selectively disrupted in podocytes by using the Cre-LoxP system. Podocyte-specific ablation of ILK resulted in heavy albuminuria, glomerulosclerosis, and kidney failure, which led to animal death beginning at 10 wk of age. Podocyte detachment and apoptosis were not observed at 4 wk of age, when albuminuria became prominent, indicating that they are not the initial cause of proteinuria. Electron microscopy revealed an early foot process effacement, as well as morphologic abnormality, in ILK-deficient podocytes. ILK deficiency caused an aberrant distribution of nephrin and alpha-actinin-4 in podocytes, whereas the localization of podocin and synaptopodin remained relatively intact. Co-immunoprecipitation demonstrated that ILK physically interacted with nephrin to form a ternary complex, and alpha-actinin-4 participated in ILK/nephrin complex formation. Therefore, ILK plays an essential role in specifying nephrin and alpha-actinin-4 distribution and in maintaining the slit diaphragm integrity and podocyte architecture. These results also illustrate that the integrin and slit diaphragm signals in podocytes are intrinsically coupled through an ILK-dependent mechanism.
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Affiliation(s)
- Chunsun Dai
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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Yasuda Y, Cohen CD, Henger A, Kretzler M. Gene expression profiling analysis in nephrology: towards molecular definition of renal disease. Clin Exp Nephrol 2006; 10:91-8. [PMID: 16791393 DOI: 10.1007/s10157-006-0421-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Accepted: 04/06/2006] [Indexed: 01/28/2023]
Abstract
The increase in progressive kidney disease, resulting in a constantly rising prevalence of endstage renal disease (ESRD), urgently warrants the development of more effective strategies to diagnose, prevent, and intervene in renal disease. Histological information obtained by renal biopsies (RBx) is a cornerstone of the current management of kidney disease. Renal tissue can provide critical information on the disease process not available by nontissue-based approaches. However, insight gained by conventional histopathology remains limited and additional strategies to define renal disease on a molecular level are required. The sequencing of the human genome, together with recent advances in genome-wide profiling techniques, has provided the framework for a comprehensive analysis of renal disease-associated transcriptional programs. In this review, strategies to apply these technological advances towards the analysis of RBx will be described, with special emphasis on their potential impact on clinical management, but also on their inherent limitations. Finally, an outlook towards the emerging proteomic studies of renal disease will be given.
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Affiliation(s)
- Yoshinari Yasuda
- Nephrologische Zentrum, Medizinische Poliklinik, Ludwig-Maximilians-Universtaet, Schillerstrasse 42, D-80336, Munich, Germany.
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Abstract
The terminally differentiated podocyte, also called glomerular visceral epithelial cell, are highly specialized cells. They function as a critical size and charge barrier to prevent proteinuria. Podocytes are injured in diabetic and non-diabetic renal diseases. The clinical signature of podocyte injury is proteinuria, with or without loss of renal function owing to glomerulosclerosis. There is an exciting and expanding literature showing that hereditary, congenital, or acquired abnormalities in the molecular anatomy of podocytes leads to proteinuria, and at times, glomerulosclerosis. The change in podocyte shape, called effacement, is not simply a passive process following injury, but is owing to a complex interplay of proteins that comprise the molecular anatomy of the different protein domains of podocytes. These will be discussed in this review. Recent studies have also highlighted that a reduction in podocyte number directly causes proteinuria and glomerulosclerosis. This is owing to several factors, including the relative inability for these cells to proliferate, detachment, and apoptosis. The mechanisms of these events are being elucidated, and are discussed in this review. It is the hope that by delineating the events following injury to podocytes, therapies might be developed to reduce the burden of proteinuric renal diseases.
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Affiliation(s)
- S J Shankland
- Department of Medicine, Division of Nephrology, University of Washington, Seattle, Washington 98195, USA.
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Ohnishi M, Hasegawa G, Yamasaki M, Obayashi H, Fukui M, Nakajima T, Ichida Y, Ohse H, Mogami SI, Yoshikawa T, Nakamura N. Integrin-linked kinase acts as a pro-survival factor against high glucose-associated osmotic stress in human mesangial cells. Nephrol Dial Transplant 2006; 21:1786-93. [PMID: 16611685 DOI: 10.1093/ndt/gfl120] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Integrin-linked kinase (ILK) is a protein that plays an important role in extracellular matrix-mediated signalling. Recent studies implicated ILK dysregulation in the development of diabetic nephropathy. However, little is known about the significance of ILK up-regulation in response to high glucose in mesangial cells. METHODS The ILK messenger (m)RNA and protein expression in human mesangial cells were analysed with quantitative real-time polymerase chain reaction (PCR) and western blotting after exposure to either 100, 200, or 500 mg/dl glucose, or 100 mg/dl glucose + 400 mg/dl mannitol. Activation of protein Kinase B (PKB)/Akt was also determined by western blot analysis. Cells were transfected with ILK siRNA to determine the effects of ILK knockdown on PKB/Akt activation and cell death following treatment with high glucose or mannitol. RESULTS High concentrations of glucose or mannitol for three days significantly up-regulated ILK mRNA and protein expression (P < 0.05 vs 100 mg/dl glucose). In contrast, ILK expression in cells exposed to the same conditions for seven days was unaffected. The time course of PKB/Akt phosphorylation was similar to that of ILK protein expression. The siRNA-mediated down-regulation of ILK expression inhibited the elevation of PKB/Akt phosphorylation induced by high glucose treatment. Furthermore, the inhibition of ILK expression promoted high glucose- or mannitol-induced apoptosis. CONCLUSION The ILK may act as a pro-survival factor and play a role in protecting mesangial cells from hyperglycaemic osmotic stress.
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Affiliation(s)
- Masayoshi Ohnishi
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Hirokoji, Kawaramachi-dori, Kamikyo-ku, Kyoto 602-8566, Japan
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