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Duan Y, Zhang D, Ye Y, Zheng S, Huang P, Zhang F, Mo G, Huang F, Yin Q, Li J, Han L. Integrated Metabolomics and Network Pharmacology to Establish the Action Mechanism of Qingrekasen Granule for Treating Nephrotic Syndrome. Front Pharmacol 2021; 12:765563. [PMID: 34938183 PMCID: PMC8685401 DOI: 10.3389/fphar.2021.765563] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/05/2021] [Indexed: 01/09/2023] Open
Abstract
Nephrotic syndrome (NS) is a clinical syndrome resulting from abnormal glomerular permeability, mainly manifesting as edema and proteinuria. Qingrekasen granule (QRKSG), a Chinese Uyghur folk medicine, is a single-flavor preparation made from chicory (Cichorium intybus L.), widely used in treating dysuria and edema. Chicory, the main component in QRKSG, effectively treats edema and protects kidneys. However, the active components in QRKSG and its underlying mechanism for treating NS remain unclear. This study explored the specific mechanism and composition of QRKSG on an NS rat model using integrated metabolomics and network pharmacology. First, metabolomics explored the relevant metabolic pathways impacted by QRKSG in the treatment of NS. Secondly, network pharmacology further explored the possible metabolite targets. Afterward, a comprehensive network was constructed using the results from the network pharmacology and metabolomics analysis. Finally, the interactions between the active components and targets were predicted by molecular docking, and the differential expression levels of the target protein were verified by Western blotting. The metabolomics results showed “D-Glutamine and D-glutamate metabolism” and “Alanine, aspartate, and glutamate metabolism” as the main targeted metabolic pathways for treating NS in rats. AKT1, BCL2L1, CASP3, and MTOR were the core QRKSG targets in the treatment of NS. Molecular docking revealed that these core targets have a strong affinity for flavonoids, terpenoids, and phenolic acids. Moreover, the expression levels of p-PI3K, p-AKT1, p-mTOR, and CASP3 in the QRKSG group significantly decreased, while BCL2L1 increased compared to the model group. These findings established the underlying mechanism of QRKSG, such as promoting autophagy and anti-apoptosis through the expression of AKT1, CASP3, BCL2L1, and mTOR to protect podocytes and maintain renal tubular function.
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Affiliation(s)
- Yanfen Duan
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China
| | - Dongning Zhang
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China
| | - Yan Ye
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China
| | - Sili Zheng
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China
| | - Ping Huang
- College of Basic Medical Sciences, Hubei University of Chinese Medicine, Wuhan, China
| | - Fengyun Zhang
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China
| | - Guoyan Mo
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China.,Key Laboratory of Traditional Chinese Medicine Resource and Prescription, Ministry of Education, Wuhan, China
| | - Fang Huang
- College of Basic Medical Sciences, Hubei University of Chinese Medicine, Wuhan, China
| | - Qiang Yin
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China.,Xinjiang Uygur Pharmaceutical Co., Ltd., Urumqi, China
| | - Jingjing Li
- College of Basic Medical Sciences, Hubei University of Chinese Medicine, Wuhan, China
| | - Lintao Han
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan, China.,Key Laboratory of Traditional Chinese Medicine Resource and Prescription, Ministry of Education, Wuhan, China
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2
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Abstract
Diabetes mellitus is a disease of dysregulated blood glucose homeostasis. The current pandemic of diabetes is a significant driver of patient morbidity and mortality, as well as a major challenge to healthcare systems worldwide. The global increase in the incidence of diabetes has prompted researchers to focus on the different pathogenic processes responsible for type 1 and type 2 diabetes. Similarly, increased morbidity due to diabetic complications has accelerated research to uncover pathological changes causing these secondary complications. Albuminuria, or protein in the urine, is a well-recognised biomarker and risk factor for renal and cardiovascular disease. Albuminuria is a mediator of pathological abnormalities in diabetes-associated conditions such as nephropathy and atherosclerosis. Clinical screening and diagnosis of diabetic nephropathy is chiefly based on the presence of albuminuria. Given the ease in measuring albuminuria, the potential of using albuminuria as a biomarker of cardiovascular diseases is gaining widespread interest. To assess the benefits of albuminuria as a biomarker, it is important to understand the association between albuminuria and cardiovascular disease. This review examines our current understanding of the pathophysiological mechanisms involved in both forms of diabetes, with specific focus on the link between albuminuria and specific vascular complications of diabetes.
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Affiliation(s)
- Pappitha Raja
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, BT9 7BL, UK
| | - Alexander P Maxwell
- Nephrology Research, Centre for Public Health, Queen's University of Belfast, Northern Ireland Regional Nephrology Unit, Belfast City Hospital, Belfast, Northern Ireland, UK
| | - Derek P Brazil
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, BT9 7BL, UK.
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3
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Kuo MC, Liang PI, Chang JM. Podocentric view of glomerular proteinuria: Focused on cytoskeletal changes and toward promising targeted therapies and challenges. Kaohsiung J Med Sci 2021; 37:539-546. [PMID: 33942997 DOI: 10.1002/kjm2.12385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 02/26/2021] [Accepted: 03/15/2021] [Indexed: 11/09/2022] Open
Abstract
Among renal cells, podocytes (glomerular epithelial cells) are the most critical to prevent plasma proteins from excessive loss by forming their sophisticated foot processes (FP) and slit diaphragms (SD). A general finding in the glomeruli of patients with nephrotic syndrome is the foot processes "effacement" resulted from dysregulated actin cytoskeleton reorganization. Ultrastructural analysis in patients with nephrotic syndrome has demonstrated that such changes tend to be dynamic and can sometimes be reversible. In a more molecular sense, injured podocytes can no longer maintain their tight regulation and "retract" their FP, but not "efface" them. Past studies have revealed multiple exquisite mechanisms and arrays of proteins participating in the regulation of cytoskeletal rearrangement, and these mechanisms serve as potential targets to treat. A major challenge to develop specific therapies is the targeted mechanism has to be crucial and specific enough for podocyte-oriented kidney diseases, and it would be even better to manifest in most of the glomerulonephritis. Studies have shown many approaches targeting different mechanisms, but none of them has been proved to be effective in clinical medicine. Up to the present, Abatacept (Orencia) is the first (and the only) clinical targeted therapy demonstrating limited success. It inhibits the co-stimulatory response of B7-1 (CD80) induced in various types of glomerulonephritis. Future clinical studies have to be expanded to substantiate this highly specific targeted therapy because the Abatacept effect is not generally accepted even within the nephrology community. Nevertheless, there are ongoing searches for specific treatment targeting podocytes through various approaches.
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Affiliation(s)
- Mei-Chuan Kuo
- Division of Nephrology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Department of Renal Care, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Peir-In Liang
- Department of Pathology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Jer-Ming Chang
- Division of Nephrology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Department of Renal Care, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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4
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Tan L, Tu Y, Wang K, Han B, Peng H, He C. Exploring protective effect of Glycine tabacina aqueous extract against nephrotic syndrome by network pharmacology and experimental verification. Chin Med 2020; 15:79. [PMID: 32765640 PMCID: PMC7395350 DOI: 10.1186/s13020-020-00361-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/26/2020] [Indexed: 02/07/2023] Open
Abstract
Background Glycine tabacina (Labill.) Benth, one of the traditional Chinese herbal medicines, has been used for treatment of nephritis, osteoporosis, rheumatism, and menopausal syndrome. The aim of this study was to illuminate the therapeutic effect and mechanism of Glycine tabacina aqueous extract (GATE) in the treatment of nephrotic syndrome (NS). Methods UHPLC-DAD-MS/MS was used to analyze the chemical profile of GATE. Adriamycin (ADR)-induced NS mouse model and network pharmacology methods were conducted to explore the protective effect and mechanism of GATE on NS treatment. Results GATE administration significantly ameliorated symptoms of proteinuria and hyperlipidemia in NS mice, as evidenced by reduced excretion of urine protein and albumin, and decreased plasma levels of total cholesterol and triglyceride. Decreased blood urea nitrogen (BUN) and creatinine levels in NS mice suggested that GATE could prevent renal function decline caused by ADR. GATE treatment also inhibited ADR-induced pathological lesions of renal tissues as indicated by periodic acid Schiff staining. Six flavonoids of GATE were identified by using UHPLC-DAD-MS/MS. Network pharmacology analysis indicated that the protection of GATE in treating NS might be associated with the regulation of oxidative stress and inflammation. In addition, the in vivo experiment validated that treatment with GATE markedly decreased reactive oxygen species production, malonaldehyde level, and increased superoxide dismutase activity both in plasma and renal tissues. TNF-α level in plasma and protein expression in kidney were significantly decreased in GATE treatment groups. Conclusions Combination of network pharmacology analysis and experimental verification revealed that GATE exerts anti-NS effect possibly through modulating oxidative stress and inflammation, suggesting the potential application of GATE or its derivatives in the prevention and treatment of NS and other related kidney diseases.
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Affiliation(s)
- Lihua Tan
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, 999078 Macao SAR China
| | - Yanbei Tu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, 999078 Macao SAR China
| | - Kai Wang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, 999078 Macao SAR China
| | - Bing Han
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, 999078 Macao SAR China
| | - Hongquan Peng
- Renal Division, Kiang Wu Hospital, Macao, 999078 Macao SAR China
| | - Chengwei He
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, 999078 Macao SAR China
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5
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Vasan R, Maleckar MM, Williams CD, Rangamani P. DLITE Uses Cell-Cell Interface Movement to Better Infer Cell-Cell Tensions. Biophys J 2019; 117:1714-1727. [PMID: 31648791 PMCID: PMC6838938 DOI: 10.1016/j.bpj.2019.09.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/17/2019] [Accepted: 09/23/2019] [Indexed: 11/30/2022] Open
Abstract
Cell shapes and connectivities evolve over time as the colony changes shape or embryos develop. Shapes of intercellular interfaces are closely coupled with the forces resulting from actomyosin interactions, membrane tension, or cell-cell adhesions. Although it is possible to computationally infer cell-cell forces from a mechanical model of collective cell behavior, doing so for temporally evolving forces in a manner robust to digitization difficulties is challenging. Here, we introduce a method for dynamic local intercellular tension estimation (DLITE) that infers such evolution in temporal force with less sensitivity to digitization ambiguities or errors. This method builds upon previous work on single time points (cellular force-inference toolkit). We validate our method using synthetic geometries. DLITE's inferred cell colony tension evolutions correlate better with ground truth for these synthetic geometries as compared to tension values inferred from methods that consider each time point in isolation. We introduce cell connectivity errors, angle estimate errors, connection mislocalization, and connection topological changes to synthetic data and show that DLITE has reduced sensitivity to these conditions. Finally, we apply DLITE to time series of human-induced pluripotent stem cell colonies with endogenously expressed GFP-tagged zonulae occludentes-1. We show that DLITE offers improved stability in the inference of cell-cell tensions and supports a correlation between the dynamics of cell-cell forces and colony rearrangement.
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Affiliation(s)
- Ritvik Vasan
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, San Diego, California
| | | | | | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, San Diego, California.
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6
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Tong S, Yang S, Li T, Gao R, Hu J, Luo T, Qing H, Zhen Q, Hu R, Li X, Yang Y, Peng C, Li Q. Role of neutrophil extracellular traps in chronic kidney injury induced by bisphenol-A. J Endocrinol 2019; 241:JOE-18-0608.R2. [PMID: 30798321 DOI: 10.1530/joe-18-0608] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 02/22/2019] [Indexed: 01/17/2023]
Abstract
Bisphenol-A (BPA) is a common environmental pollutant, and exposure to it is associated with proteinuria and may predict the progression of chronic kidney disease,however, the mechanism is not clear. Neutrophil extracellular traps (NETs) is a DNA skeleton coated with various proteases, and it is associated with various autoimmune nephritis. In this study, we examine whether NETs is involved in BPA-induced chronic kidney injury. In vivo, BPA exposure resulted in impaired renal function and altered renal morphology, including glomerular mesangial matrix expansion and increased renal interstitial fibroblast markers. Meanwhile, more dsDNA can be detected in the serum, and the NETs-associated proteins, MPO and citH3 were deposited in the renal system. In vitro, BPA and NETs treatment caused podocyte injury, a loss of marker proteins, and disorder in the actin skeleton. After NETs inhibition via DNase administration, BPA-induced injuries were significantly relieved. In conclusion, the increase of NETosis in circulation and the renal system during BPA exposure suggests that NETs may be involved in BPA-induced chronic kidney injury.
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Affiliation(s)
- Shiyun Tong
- S Tong, Department of Endocrinology , The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Shumin Yang
- S Yang, Department of Endocrinology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ting Li
- T Li, Department of Endocrinology, Department of Endocrinology, the First Affiliated Hospital of Chengdu Medical College, ChengDu, China
| | - Rufei Gao
- R Gao, Laboratory of Reproductive Biology, School of Public Health and Management, Chongqing Medical University, Chongqing 400016, China, Chongqing Medical University, Chongqing, China
| | - Jinbo Hu
- J Hu, Department of Endocrinology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China., Chongqing, 400016, China
| | - Ting Luo
- T Luo, Department of Endocrinology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Hua Qing
- H Qing, Department of Endocrinology, the First Affiliated Hospital of Chongqing Medical University, ChongQing, China
| | - Qianna Zhen
- Q Zhen, Department of Endocrinology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China
| | - Renzhi Hu
- R Hu, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China, Department of Endocrinology, Chongqing, China
| | - Xuan Li
- X Li, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China, Department of Endocrinology, Chongqing, China
| | - Yi Yang
- Y Yang, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China, Department of Endocrinology, Chongqing, China
| | - Chuan Peng
- C Peng, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China, The Chongqing Key Laboratory of Translational Medicine in Major Metabolic Diseases, Chongqing, China
| | - Qifu Li
- Q Li, Department of Endocrine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
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7
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Huang QY, Lai XN, Qian XL, Lv LC, Li J, Duan J, Xiao XH, Xiong LX. Cdc42: A Novel Regulator of Insulin Secretion and Diabetes-Associated Diseases. Int J Mol Sci 2019; 20:ijms20010179. [PMID: 30621321 PMCID: PMC6337499 DOI: 10.3390/ijms20010179] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 12/26/2018] [Accepted: 12/29/2018] [Indexed: 02/07/2023] Open
Abstract
Cdc42, a member of the Rho GTPases family, is involved in the regulation of several cellular functions including cell cycle progression, survival, transcription, actin cytoskeleton organization and membrane trafficking. Diabetes is a chronic and metabolic disease, characterized as glycometabolism disorder induced by insulin deficiency related to β cell dysfunction and peripheral insulin resistance (IR). Diabetes could cause many complications including diabetic nephropathy (DN), diabetic retinopathy and diabetic foot. Furthermore, hyperglycemia can promote tumor progression and increase the risk of malignant cancers. In this review, we summarized the regulation of Cdc42 in insulin secretion and diabetes-associated diseases. Organized researches indicate that Cdc42 is a crucial member during the progression of diabetes, and Cdc42 not only participates in the process of insulin synthesis but also regulates the insulin granule mobilization and cell membrane exocytosis via activating a series of downstream factors. Besides, several studies have demonstrated Cdc42 as participating in the pathogenesis of IR and DN and even contributing to promote cancer cell proliferation, survival, invasion, migration, and metastasis under hyperglycemia. Through the current review, we hope to cast light on the mechanism of Cdc42 in diabetes and associated diseases and provide new ideas for clinical diagnosis, treatment, and prevention.
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Affiliation(s)
- Qi-Yuan Huang
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
| | - Xing-Ning Lai
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
| | - Xian-Ling Qian
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
| | - Lin-Chen Lv
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
| | - Jun Li
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
| | - Jing Duan
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
| | - Xing-Hua Xiao
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
| | - Li-Xia Xiong
- Department of Pathophysiology, Medical College, Nanchang University, Jiangxi Province Key Laboratory of Tumor Pathogenesis and Molecular Pathology, 461 Bayi Road, Nanchang 330006, China.
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Dakovic Bjelakovic M, Vlajkovic S, Bjelakovic M. Ultramorphological Characteristics of Podocyte Development in the Human Fetal Metanephros. Cells Tissues Organs 2018; 205:42-52. [PMID: 29414801 DOI: 10.1159/000486545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 12/28/2017] [Indexed: 11/19/2022] Open
Abstract
The aim of this study was to determine the developmental characteristics of podocytes in the human fetal metanephros using scanning electron microscopy, light microscopy, and transmission electron microscopy. Kidney samples of 15 human fetuses of both sexes (gestational age 10-22 weeks) were analyzed. At the S-shaped body stage, primitive podocytes were arranged in a layer of cuboidal cells beneath the vascular cleft. When observed from Bowman's space, the demarcation between adjacent podocytes was not clear, but mild depressions indicated cell boundaries. At the more advanced S-shaped body stage, podocytes were polygonal, with a flat apical surface. They were in close contact, but boundaries between adjacent cells were distinct. After initial separation of their apical parts, podocytes continued to separate from each other along their lateral sides. Their shape changed from polygonal to spherical, resembling clusters of grapes. Cytoplasmic buds could be seen at the base of some podocytes initially, when all podocytes were spherical. Parallel with the development of the first capillary loops, wider intercellular spaces were noted between elliptical-shaped podocytes. Podocytes then developed cytoplasmic processes and became flattened and star shaped. Their cell bodies separated from the glomerular basement membrane through the insertion of thick processes under the cell body. Thick primary processes ramified to form the foot processes, which interdigitated on the surface of capillary loops. During the capillary loop stage, the degree of differentiation of the podocytes varied among various glomerular regions, as well as within the same capillary loop.
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9
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Müller-Deile J, Schiffer M. Podocytes from the diagnostic and therapeutic point of view. Pflugers Arch 2017; 469:1007-1015. [PMID: 28508947 DOI: 10.1007/s00424-017-1993-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 05/04/2017] [Indexed: 01/23/2023]
Abstract
The central role of podocytes in glomerular diseases makes this cell type an interesting diagnostic tool as well as a therapeutic target. In this review, we discuss the current literature on the use of podocytes and podocyte-specific markers as non-invasive diagnostic tools in different glomerulopathies. Furthermore, we highlight the direct effects of drugs currently used to treat primary glomerular diseases and describe their direct cellular effects on podocytes. A new therapeutic potential is seen in drugs targeting the podocytic actin cytoskeleton which is essential for podocyte foot process structure and function. Incubation of cultured human podocyte cell lines with sera from patients with active glomerular diseases is currently also used to identify novel circulating factors with pathophysiological relevance for the glomerular filtration barrier. In addition, treatment of detached urinary podocytes from patients with substances that restore their cytoskeleton might serve as a novel personalized tool to estimate their potential for podocyte recovery ex vivo.
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Affiliation(s)
- Janina Müller-Deile
- Department of Nephrology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Mario Schiffer
- Department of Nephrology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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10
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Fu Y, Zhu JY, Richman A, Zhao Z, Zhang F, Ray PE, Han Z. A Drosophila model system to assess the function of human monogenic podocyte mutations that cause nephrotic syndrome. Hum Mol Genet 2017; 26:768-780. [PMID: 28164240 DOI: 10.1093/hmg/ddw428] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 12/16/2016] [Indexed: 12/15/2022] Open
Abstract
Many genetic mutations have been identified as monogenic causes of nephrotic syndrome (NS), but important knowledge gaps exist in the roles of these genes in kidney cell biology and renal diseases. More animal models are needed to assess the functions of these genes in vivo, and to determine how they cause NS in a timely manner. Drosophila nephrocytes and human podocytes share striking similarities, but to what degree these known NS genes play conserved roles in nephrocytes remains unknown. Here we systematically studied 40 genes associated with NS, including 7 that have not previously been analysed for renal function in an animal model. We found that 85% of these genes are required for nephrocyte functions, suggesting that a majority of human genes known to be associated with NS play conserved roles in renal function from flies to humans. To investigate functional conservation in more detail, we focused on Cindr, the fly homolog of the human NS gene CD2AP. Silencing Cindr in nephrocytes led to dramatic nephrocyte functional impairment and shortened life span, as well as collapse of nephrocyte lacunar channels and effacement of nephrocyte slit diaphragms. These phenotypes could be rescued by expression of a wild-type human CD2AP gene, but not a mutant allele derived from a patient with CD2AP-associated NS. We conclude that the Drosophila nephrocyte can be used to elucidate clinically relevant molecular mechanisms underlying the pathogenesis of most monogenic forms of NS, and to efficiently generate personalized in vivo models of genetic renal diseases bearing patient-specific mutations.
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Affiliation(s)
- Yulong Fu
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA
| | - Jun-Yi Zhu
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA
| | - Adam Richman
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA
| | - Zhanzheng Zhao
- Department of Nephrology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China
| | - Fujian Zhang
- Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, People's Republic of China
| | - Patricio E Ray
- Center for Genetic Medicine Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Zhe Han
- Center for Cancer and Immunology Research, Children's National Health Systems, 111 Michigan Ave. NW, Washington, DC, USA.,Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
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11
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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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12
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Immunohistochemical and electronmicroscopic features of mesenchymal-to-epithelial transition in human developing, postnatal and nephrotic podocytes. Histochem Cell Biol 2016; 147:481-495. [DOI: 10.1007/s00418-016-1507-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2016] [Indexed: 01/13/2023]
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13
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Zennaro C, Rastaldi MP, Bakeine GJ, Delfino R, Tonon F, Farra R, Grassi G, Artero M, Tormen M, Carraro M. A nanoporous surface is essential for glomerular podocyte differentiation in three-dimensional culture. Int J Nanomedicine 2016; 11:4957-4973. [PMID: 27757030 PMCID: PMC5053378 DOI: 10.2147/ijn.s110201] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although it is well recognized that cell–matrix interactions are based on both molecular and geometrical characteristics, the relationship between specific cell types and the three-dimensional morphology of the surface to which they are attached is poorly understood. This is particularly true for glomerular podocytes – the gatekeepers of glomerular filtration – which completely enwrap the glomerular basement membrane with their primary and secondary ramifications. Nanotechnologies produce biocompatible materials which offer the possibility to build substrates which differ only by topology in order to mimic the spatial organization of diverse basement membranes. With this in mind, we produced and utilized rough and porous surfaces obtained from silicon to analyze the behavior of two diverse ramified cells: glomerular podocytes and a neuronal cell line used as a control. Proper differentiation and development of ramifications of both cell types was largely influenced by topographical characteristics. Confirming previous data, the neuronal cell line acquired features of maturation on rough nanosurfaces. In contrast, podocytes developed and matured preferentially on nanoporous surfaces provided with grooves, as shown by the organization of the actin cytoskeleton stress fibers and the proper development of vinculin-positive focal adhesions. On the basis of these findings, we suggest that in vitro studies regarding podocyte attachment to the glomerular basement membrane should take into account the geometrical properties of the surface on which the tests are conducted because physiological cellular activity depends on the three-dimensional microenvironment.
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Affiliation(s)
- Cristina Zennaro
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste
| | | | - Gerald James Bakeine
- Department of Radiology, San Martino University Hospital, University of Genoa, Genoa
| | - Riccarda Delfino
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste
| | - Federica Tonon
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste
| | - Rossella Farra
- Department of Engineering and Architecture, University of Trieste
| | - Gabriele Grassi
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste; Department of Life Sciences, Cattinara University Hospital, University of Trieste
| | - Mary Artero
- Azienda Sanitaria Universitaria Integrata di Trieste, Trieste
| | | | - Michele Carraro
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste
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14
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Yamamoto-Nonaka K, Koike M, Asanuma K, Takagi M, Oliva Trejo JA, Seki T, Hidaka T, Ichimura K, Sakai T, Tada N, Ueno T, Uchiyama Y, Tomino Y. Cathepsin D in Podocytes Is Important in the Pathogenesis of Proteinuria and CKD. J Am Soc Nephrol 2016; 27:2685-700. [PMID: 26823550 DOI: 10.1681/asn.2015040366] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 11/30/2015] [Indexed: 12/24/2022] Open
Abstract
Studies have revealed many analogies between podocytes and neurons, and these analogies may be key to elucidating the pathogenesis of podocyte injury. Cathepsin D (CD) is a representative aspartic proteinase in lysosomes. Central nervous system neurons in CD-deficient mice exhibit a form of lysosomal storage disease with a phenotype resembling neuronal ceroid lipofuscinoses. In the kidney, the role of CD in podocytes has not been fully explored. Herein, we generated podocyte-specific CD-knockout mice that developed proteinuria at 5 months of age and ESRD by 20-22 months of age. Immunohistochemical analysis of these mice showed apoptotic podocyte death followed by proteinuria and glomerulosclerosis with aging. Using electron microscopy, we identified, in podocytes, granular osmiophilic deposits (GRODs), autophagosome/autolysosome-like bodies, and fingerprint profiles, typical hallmarks of CD-deficient neurons. CD deficiency in podocytes also led to the cessation of autolysosomal degradation and accumulation of proteins indicative of autophagy impairment and the mitochondrial ATP synthase subunit c accumulation in the GRODs, again similar to changes reported in CD-deficient neurons. Furthermore, both podocin and nephrin, two essential components of the slit diaphragm, translocated to Rab7- and lysosome-associated membrane glycoprotein 1-positive amphisomes/autolysosomes that accumulated in podocyte cell bodies in podocyte-specific CD-knockout mice. We hypothesize that defective lysosomal activity resulting in foot process effacement caused this accumulation of podocin and nephrin. Overall, our results suggest that loss of CD in podocytes causes autophagy impairment, triggering the accumulation of toxic subunit c-positive lipofuscins as well as slit diaphragm proteins followed by apoptotic cell death.
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Affiliation(s)
- Kanae Yamamoto-Nonaka
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | | | - Katsuhiko Asanuma
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan; TMK Project, Medical Innovation Center, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Miyuki Takagi
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | | | - Takuto Seki
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Teruo Hidaka
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | | | | | - Norihiro Tada
- Division of Genome Research, Research Institute for Diseases of Old Ages
| | - Takashi Ueno
- Laboratory of Proteomics and Biomolecular Science, Research Support Center
| | - Yasuo Uchiyama
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Tokyo, Japan; and
| | - Yasuhiko Tomino
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan;
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15
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Ha TS, Park HY, Seong SB, Ahn HY. Puromycin aminonucleoside increases podocyte permeability by modulating ZO-1 in an oxidative stress-dependent manner. Exp Cell Res 2015; 340:139-49. [PMID: 26683996 DOI: 10.1016/j.yexcr.2015.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/17/2015] [Accepted: 12/08/2015] [Indexed: 11/30/2022]
Abstract
Puromycin aminonucleoside (PAN)-induced nephrosis is a widely studied animal model of human idiopathic nephrotic syndrome because PAN injection into rats results in increased glomerular permeability with the characteristic ultrastructural changes in podocytes similar to human nephrosis. To investigate the role of zonula occludens (ZO)-1 and oxidative stress on PAN-induced podocyte phenotypical changes and hyperpermeability in vitro, we cultured rat and mouse podocytes and treated with various concentrations of PAN. PAN treatment increased oxidative stress level of podocytes significantly with the induction of Nox4. In addition, PAN changed the ultrastructure of podocytes, such as shortening and fusion of microvilli, and the separation of intercellular gaps, which were improved by anti-oxidative vitamin C and Nox4 siRNA. PAN also disrupted the intercellular linear ZO-1 staining and induced inner cytoplasmic re-localization of ZO-1 protein, resulting in increased podocyte intercellular permeability. PAN reduced ZO-1 protein amount and mRNA expression in a dose-dependent manner, which means that PAN could also modulate ZO-1 protein transcriptionally. However, the decreased ZO-1 protein of podocytes by PAN was improved by Nox4 siRNA transfection. Furthermore, vitamin C mitigated the quantitative and distributional disturbances of ZO-1 protein caused by PAN. Our results demonstrate that the phenotypical changes of intercellular ZO-1 by oxidative stress via Nox4 likely contribute to the glomerular hyperpermeability caused by PAN.
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Affiliation(s)
- Tae-Sun Ha
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, South Korea.
| | - Hye-Young Park
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, South Korea
| | - Su-Bin Seong
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, South Korea
| | - Hee Yul Ahn
- Department of Pharmacology, College of Medicine, Chungbuk National University, Cheongju, South Korea
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16
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Keir LS, Firth R, May C, Ni L, Welsh GI, Saleem MA. Generating conditionally immortalised podocyte cell lines from wild-type mice. Nephron Clin Pract 2015; 129:128-36. [PMID: 25720381 DOI: 10.1159/000369816] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 11/10/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Understanding podocyte biology is key to deciphering the pathogenesis of numerous glomerular diseases. However, cultivation of primary podocytes results in dedifferentiation with loss of specialised architecture. Human conditionally immortalised podocytes partly overcome this problem, utilising a temperature-sensitive transgene. Conditionally immortalised murine podocytes exist, but are derived from the Immortomouse. METHODS Using retroviral temperature-sensitive SV40 transfection, we created a conditionally immortalised podocyte cell line from wild-type mice. RESULTS These cells develop characteristic mature podocyte morphology and robustly express slit diaphragm proteins. Functionally, these cells demonstrate comparable responses in motility and glucose uptake to human conditionally immortalised podocytes. CONCLUSION Podocyte-specific transgenic mice are extensively used to study glomerular disease and this technique could be used to make podocyte cell lines from any mouse, allowing study at the cellular level. This will help characterise these disease models and add to the laboratory resources used to study podocytopathies and glomerular disease.
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17
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Datta N, Lindfors S, Miura N, Saleem MA, Lehtonen S. Overexpression of transcription factor FOXC2 in cultured human podocytes upregulates injury markers and increases motility. Exp Cell Res 2015; 340:32-42. [PMID: 26524507 DOI: 10.1016/j.yexcr.2015.10.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 10/09/2015] [Accepted: 10/29/2015] [Indexed: 01/23/2023]
Abstract
Obesity and diabetes-related kidney diseases associate with renal failure and cardiovascular morbidity, and represent a major health issue worldwide. However, the molecular mechanisms leading to their development remain poorly understood. We observed increased expression of transcription factor FoxC2 in the podocytes of obese Zucker rats that are insulin resistant and albuminuric. We also found that depletion of adiponectin, an adipocyte-derived hormone whose secretion is decreased in obesity, upregulated FOXC2 in differentiated human podocytes in vitro. Overexpression of FOXC2 in cultured human podocytes led to increased nuclear expression of FOXC2 associated with a change of cellular morphology. This was accompanied by upregulation of vimentin, a key mesenchymal marker, and active beta-catenin, associated with podocyte injury. We also observed re-organization of the actin cytoskeleton, disrupted localization of the tight junction protein ZO-1, and increased motility of podocytes overexpressing FOXC2. These data indicate that the expression of FOXC2 in podocytes needs to be tightly regulated, and that its overexpression induces a chain of cellular events leading to podocyte dysfunction. These changes may lead to podocyte detachment and depletion ultimately contributing to albuminuria. We also suggest a novel molecular mechanism linking obesity-induced decrease in adiponectin to podocyte dysfunction via upregulation of FOXC2.
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Affiliation(s)
- Neeta Datta
- Department of Pathology, University of Helsinki, 00290 Helsinki, Finland
| | - Sonja Lindfors
- Department of Pathology, University of Helsinki, 00290 Helsinki, Finland
| | - Naoyuki Miura
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Moin A Saleem
- Academic and Children's Renal Unit, Dorothy Hodgkin Building, Bristol BS1, United Kingdom
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, 00290 Helsinki, Finland.
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18
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Chebotareva NV, Bobkova IN, Neprintseva NV, Kozlovskaya LV, Malkandueva ZT. [Urinary biomarkers for podocyte injury: Significance for evaluating the course and prognosis of chronic glomerulonephritis]. TERAPEVT ARKH 2015; 87:34-39. [PMID: 26281193 DOI: 10.17116/terarkh201587634-39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AIM To estimate the degree of podocyte injury in patients with different types of chronic glomerulonephritis (CGN) from the urinary level of podocyte markers and to determine the significance of these indicators as criteria for disease activity and prognosis. SUBJECTS AND METHODS Seventy-three patients with CGN, including 20 with inactive nephritis (Group 1), 23 with obvious urological syndrome (Group 2), 30 with nephrotic syndrome (NS) (Group 3), among them there were 7 patients with severe NS and 7 with NS concurrent with acute nephritic syndrome, were examined. A control group consisted of 8 healthy individuals. In the examined groups, the degree of podocyturia (PCU) was investigated by flow cytometry using podocalyxin-labeled antibodies and the levels of nephrinuria (NU), heat shock protein 27 (HSP27) in urine, interleukin 6 (IL-6), caspase 9, and vascular endothelial growth factor (VEGF) were estimated by ELISA. RESULTS The patients with active CGN were found to have a high level of markers for podocyte injury: PCU and NU, which correlate with the magnitude of proteinuria, severity of NS, and degree of podocytopenia. Those with the severest NS, that concurrent with renal dysfunction in particular, were observed to have a progressive imbalance of inflammatory (IL-6), apoptotic (caspase-9), and defensive (HSP27 and VEGF) factors, which displays the incompetence of self-defense mechanisms in podocytes and contributes to the torpid course of CGN. Progressive PCU and NU are a poor prognostic sign indicating the risk of glomerulonephritis. CONCLUSION The indicators considered are universal for all patients with CGN running with proteinuria and may be used to monitor the course of the disease; moreover, the damaging factors should be considered in conjunction with the defensive factors.
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Affiliation(s)
- N V Chebotareva
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
| | - I N Bobkova
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
| | - N V Neprintseva
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
| | - L V Kozlovskaya
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
| | - Z T Malkandueva
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
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19
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Alteration in the podoplanin-ezrin-cytoskeleton linkage is an important initiation event of the podocyte injury in puromycin aminonucleoside nephropathy, a mimic of minimal change nephrotic syndrome. Cell Tissue Res 2015; 362:201-13. [PMID: 25920588 DOI: 10.1007/s00441-015-2178-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 03/20/2015] [Indexed: 10/23/2022]
Abstract
Podoplanin was identified as a protein associated with the transformation of arborized foot processes of glomerular epithelial cells (podocytes) to flat feet. However, the function of podoplanin in the podocyte is not yet fully clarified. In this study, we analyzed the molecular nature of podoplanin, and its expression in rat nephrotic models and patients with minimal change nephrotic syndrome (MCNS). We demonstrated here that podoplanin has two forms: one contains abundant sialic acid and the other a lesser amount of sialic acid. Podoplanin bound ezrin to interact with the cytoskeleton. The silencing of podoplanin in cultured podocytes caused a change in the cell shape and the distribution of ezrin and actin. The expression of podoplanin was clearly reduced before the onset of proteinuria in puromycin aminonucleoside (PAN) nephropathy, a mimic of MCNS, and the decrease in the expression of podoplanin became more evident at the proteinuric stage. Podoplanin was detected in normal urine samples, and the amount of urinary podoplanin markedly increased on day 1 of PAN nephropathy. Urinary ezrin was also detected. The amount of the phosphorylated ezrin was reduced, while the amount of the podoplanin-interacting ezrin increased. The podoplanin expression was reduced in a patient with active-phase MCNS. It is conceivable that the alteration of the podoplanin-ezrin-cytoskeleton linkage is an important event of the podocyte injury in MCNS.
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20
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Hulkko J, Patrakka J, Lal M, Tryggvason K, Hultenby K, Wernerson A. Neph1 is reduced in primary focal segmental glomerulosclerosis, minimal change nephrotic syndrome, and corresponding experimental animal models of adriamycin-induced nephropathy and puromycin aminonucleoside nephrosis. NEPHRON EXTRA 2014; 4:146-54. [PMID: 25404935 PMCID: PMC4202611 DOI: 10.1159/000365091] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND/AIMS The transmembrane proteins Neph1 and nephrin form a complex in the slit diaphragm (SD) of podocytes. As recent studies indicate an involvement of this complex in the polymerization of the actin cytoskeleton and proteinuria, we wanted to study the subcellular localization of Neph1 in the normal human kidney and its expression in focal segmental glomerulosclerosis (FSGS), minimal change nephrotic syndrome (MCNS), and the corresponding experimental models of Adriamycin-induced nephropathy (ADR) and puromycin aminonucleoside nephrosis (PAN). All these disorders are characterized by substantial foot process effacement (FPE) and proteinuria. MATERIALS AND METHODS Kidney biopsies from patients with primary FSGS (perihilar type) and MCNS were compared to normal renal tissue. Mouse and rat kidney cortices from days 7 and 14 after Adriamycin injection and days 2 and 4 after puromycin aminonucleoside injection, respectively, were compared to control mouse and rat kidney. Polyclonal antibodies against Neph1 and nephrin were used for immunoelectron microscopy, and semiquantification was performed. RESULTS We localized Neph1 mainly to, and in close proximity to, the SD. Double staining of Neph1 and nephrin showed the proteins to be in close connection in the SD. The total amount of Neph1 in the podocytes was significantly reduced in FSGS, MCNS, ADR, and PAN. The reduction of Neph1 was also seen in areas with and without FPE. Nephrin was reduced in MCNS and PAN but unchanged in FSGS. CONCLUSION With nephrin (but not Neph1) unchanged in FSGS, there might be a disruption of the complex and an involvement of Neph1 in its pathogenesis.
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Affiliation(s)
- Jenny Hulkko
- Department of Clinical Science, Intervention and Technology, Stockholm, Sweden
| | - Jaakko Patrakka
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Mark Lal
- Department of Medical Biochemistry and Biophysics, Stockholm, Sweden
| | - Karl Tryggvason
- Department of Medical Biochemistry and Biophysics, Stockholm, Sweden
| | - Kjell Hultenby
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Annika Wernerson
- Department of Clinical Science, Intervention and Technology, Stockholm, Sweden
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21
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Sir Elkhatim R, Li JYZ, Yong TY, Gleadle JM. Dipping your feet in the water: podocytes in urine. Expert Rev Mol Diagn 2014; 14:423-37. [PMID: 24724555 DOI: 10.1586/14737159.2014.908122] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Podocyte injury and loss plays an important role in the pathogenesis and progression of many kidney diseases. Studies have shown that podocyte-related markers and products can be detected in the urine of patients with glomerular diseases such as focal segmental glomerulosclerosis, IgA nephropathy, lupus nephritis, diabetic nephropathy and pre-eclampsia. Therefore, detecting the loss of podocytes in the urine provides a useful noninvasive technique of gathering information about the disease type and/or activity of glomerular diseases. Currently, urine podocyte-related protein markers, mRNA, microRNA and exosomes have been used with varying degrees of success to study glomerular diseases. The determination of urinary podocyte loss may become an important noninvasive tool in the evaluation of glomerular diseases.
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Affiliation(s)
- Rashid Sir Elkhatim
- Department of Renal Medicine, Flinders Medical Centre, Adelaide, South Australia
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22
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He FF, Chen S, Su H, Meng XF, Zhang C. Actin-associated Proteins in the Pathogenesis of Podocyte Injury. Curr Genomics 2014; 14:477-84. [PMID: 24396279 PMCID: PMC3867723 DOI: 10.2174/13892029113146660014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 09/24/2013] [Accepted: 09/25/2013] [Indexed: 02/07/2023] Open
Abstract
Podocytes have a complex cellular architecture with interdigitating processes maintained by a precise organization of actin filaments. The actin-based foot processes of podocytes and the interposed slit diaphragm form the final barrier to proteinuria. The function of podocytes is largely based on the maintenance of the normal foot process structure with actin cytoskeleton. Cytoskeletal dynamics play important roles during normal podocyte development, in maintenance of the healthy glomerular filtration barrier, and in the pathogenesis of glomerular diseases. In this review, we focused on recent findings on the mechanisms of organization and reorganization of these actin-related molecules in the pathogenesis of podocyte injury and potential therapeutics targeting the regulation of actin cytoskeleton in podocytopathies.
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Affiliation(s)
- Fang-Fang He
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Shan Chen
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Hua Su
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xian-Fang Meng
- Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chun Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Merscher S, Fornoni A. Podocyte pathology and nephropathy - sphingolipids in glomerular diseases. Front Endocrinol (Lausanne) 2014; 5:127. [PMID: 25126087 PMCID: PMC4115628 DOI: 10.3389/fendo.2014.00127] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/14/2014] [Indexed: 01/10/2023] Open
Abstract
Sphingolipids are components of the lipid rafts in plasma membranes, which are important for proper function of podocytes, a key element of the glomerular filtration barrier. Research revealed an essential role of sphingolipids and sphingolipid metabolites in glomerular disorders of genetic and non-genetic origin. The discovery that glucocerebrosides accumulate in Gaucher disease in glomerular cells and are associated with clinical proteinuria initiated intensive research into the function of other sphingolipids in glomerular disorders. The accumulation of sphingolipids in other genetic diseases including Tay-Sachs, Sandhoff, Fabry, hereditary inclusion body myopathy 2, Niemann-Pick, and nephrotic syndrome of the Finnish type and its implications with respect to glomerular pathology will be discussed. Similarly, sphingolipid accumulation occurs in glomerular diseases of non-genetic origin including diabetic kidney disease (DKD), HIV-associated nephropathy, focal segmental glomerulosclerosis (FSGS), and lupus nephritis. Sphingomyelin metabolites, such as ceramide, sphingosine, and sphingosine-1-phosphate have also gained tremendous interest. We recently described that sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) is expressed in podocytes where it modulates acid sphingomyelinase activity and acts as a master modulator of danger signaling. Decreased SMPDL3b expression in post-reperfusion kidney biopsies from transplant recipients with idiopathic FSGS correlates with the recurrence of proteinuria in patients and in experimental models of xenotransplantation. Increased SMPDL3b expression is associated with DKD. The consequences of differential SMPDL3b expression in podocytes in these diseases with respect to their pathogenesis will be discussed. Finally, the role of sphingolipids in the formation of lipid rafts in podocytes and their contribution to the maintenance of a functional slit diaphragm in the glomerulus will be discussed.
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Affiliation(s)
- Sandra Merscher
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, Miami, FL, USA
- *Correspondence: Sandra Merscher, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 628, Miami, FL 33136, USA e-mail: ; Alessia Fornoni, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 633, Miami, FL 33136, USA e-mail:
| | - Alessia Fornoni
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, Miami, FL, USA
- *Correspondence: Sandra Merscher, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 628, Miami, FL 33136, USA e-mail: ; Alessia Fornoni, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 633, Miami, FL 33136, USA e-mail:
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24
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Ha TS. Roles of adaptor proteins in podocyte biology. World J Nephrol 2013; 2:1-10. [PMID: 24175259 PMCID: PMC3782205 DOI: 10.5527/wjn.v2.i1.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/26/2012] [Accepted: 01/06/2013] [Indexed: 02/06/2023] Open
Abstract
Podocytes covering the glomerular basement membrane over the glomerular capillary consist of three morphologically and functionally different segments, the cell body, major processes and extending finger-like foot processes (FPs). The FPs of neighboring podocytes are connected by a continuous adherent junction structure named the slit diaphragm (SD). The extracellular SD is linked to the intracellular, a highly dynamic, cytoskeleton through adaptor proteins. These adaptor proteins, such as CD2-associated protein, zonula occludens 1, β-catenin, Nck and p130Cas, located at the intracellular SD insertion area near lipid rafts, have important structural and functional roles. Adaptor proteins in podocytes play important roles as a structural component of the podocyte structure, linking the SD to the cytoskeletal structure and as a signaling platform sending signals from the SD to the actin cytoskeleton. This review discusses the roles of adaptor proteins in the podocyte cytoskeletal structure and signaling from the SD to the actin cytoskeleton.
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25
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Ha TS, Choi JY, Park HY. Puromycin aminonucleoside modulates p130Cas of podocytes. KOREAN JOURNAL OF PEDIATRICS 2012; 55:371-6. [PMID: 23133483 PMCID: PMC3488612 DOI: 10.3345/kjp.2012.55.10.371] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 04/18/2012] [Accepted: 07/09/2012] [Indexed: 01/25/2023]
Abstract
PURPOSE Puromycin aminonucleoside (PAN) specifically injures podocytes, leading to foot process effacement, actin cytoskeleton disorganization, and abnormal distribution of slit diaphragm proteins. p130Cas is a docking protein connecting F-actin fibers to the glomerular basement membrane (GBM) and adapter proteins in glomerular epithelial cells (GEpCs; podocytes). We investigated the changes in the p130Cas expression level in the PAN-induced pathological changes of podocytes in vitro. METHODS We observed changes in the p130Cas expression in cultured rat GEpCs and mouse podocytes treated with various concentrations of PAN and antioxidants, including probucol, epigallocatechin gallate (EGCG), and vitamin C. The changes in the p130Cas expression level were analyzed using confocal immunofluorescence imaging, Western blotting, and polymerase chain reaction. RESULTS In the immunofluorescence study, p130Cas showed a diffuse cytoplasmic distribution with accumulation at distinct sites visible as short stripes and colocalized with P-cadherin. The fluorescences of the p130Cas protein were internalized and became granular by PAN administration in a dose-dependent manner, which had been restored by antioxidants, EGCG and vitamin C. PAN also decreased the protein and mRNA expression levels of p130Cas at high doses and in a longer exposed duration, which had been also reversed by antioxidants. CONCLUSION These findings suggest that PAN modulates the quantitative and distributional changes of podocyte p130Cas through oxidative stress resulting in podocyte dysfunction.
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Affiliation(s)
- Tae-Sun Ha
- Department of Pediatrics, Chungbuk National University College of Medicine, Cheongju, Korea. ; Postgraduate School, Chungbuk National University College of Medicine, Cheongju, Korea
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El-Gerbed MSA. Protective effect of lycopene on deltamethrin-induced histological and ultrastructural changes in kidney tissue of rats. Toxicol Ind Health 2012; 30:160-73. [PMID: 22865284 DOI: 10.1177/0748233712448115] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Deltamethrin is globally used in crop protection and control of malaria and other vector-borne diseases. It has a potent insecticidal activity with an appreciable safety margin. However, a number of studies have demonstrated nephrotoxicity of deltamethrin in mammalian and nonmammalian species. Lycopene, a carotenoid occurring naturally in tomatoes, has attracted considerable attention as an antioxidant. This study was focused on investigating the possible protective effect of coadministration of lycopene on deltamethrin toxicity. In this study, male albino rats were divided into four groups of 10 animals each: group I served as control, which received standard diet; group II received oral administration of deltamethrin (1.28 mg/kg per day) for 30 days; group III received both deltamethrin and lycopene (1 mg/kg per day); group IV received lycopene (1 mg/kg per day). After the experiment, the animals were anesthetized and the cytokine, tumor necrosis factor-α (TNF-α), in the serum was measured; the kidney was taken for histological and ultrastructural studies. Deltamethrin significantly increased the TNF-α. The histopathological examination of kidney showed mild necrotic changes. Ultrastructural changes in renal proximal tubules of deltamethrin-treated group included an increased number and irregular shape of mitochondria with sparse fragmented cristae, serious ultrastructural lesions in renal proximal tubular lining cells, vacuolar degeneration in the epithelial cells, increased number of lysosomes and loss of apical microvilli. In addition, focal segmental thickening and the duplication of glomerular basement membrane and podocyte changes were observed. Histopathological and ultrastructural study showed some protective effect of lycopene on kidney tissues.
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Zou L, Xu HG, Ren W, Jin R, Wang Y, Zhou GP. Transcriptional activation of the human CD2AP promoter by E2F1. PLoS One 2012; 7:e42774. [PMID: 22880102 PMCID: PMC3411847 DOI: 10.1371/journal.pone.0042774] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/11/2012] [Indexed: 12/24/2022] Open
Abstract
CD2-associated protein (CD2AP) is an adaptor molecule involved in T cell receptor signaling and podocyte homeostasis. CD2AP-deficient mice develop nephritic syndrome and renal failure caused by glomerulosclerosis. Transcription factor E2F1 is a key regulator of cell proliferation and apoptosis. Here we report that E2F1 up-regulates the human CD2AP promoter and further increases the mRNA and protein levels of the human CD2AP in human embryonic kidney (HEK) 293 cells. By semi-quantitative RT-PCR and Western blot analysis we demonstrate that ectopic expression of E2F1 elevates the mRNA and protein levels of CD2AP. Consistently, transient transfection assays prove that overexpression of E2F1 transactivates the CD2AP promoter while knocking-down of endogenous E2F1 by a shRNA strategy results in reduction of the CD2AP promoter activity. Toward understanding the underlying mechanism of this regulation, we performed chromatin immunoprecipitation and mutations of the putative Sp1 binding sites, demonstrating that E2F1 can bind to Sp1 binding site and overexpression of E2F1 is capable of increasing the binding of E2F1 and decreasing the binding of Sp1 to Sp1 binding sites.
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Affiliation(s)
- Li Zou
- Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Hua-Guo Xu
- Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
- Department of Clinical Laboratory, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Wei Ren
- Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Rui Jin
- Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Yi Wang
- Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Guo-Ping Zhou
- Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
- * E-mail:
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Kim SH, Jang YW, Hwang P, Kim HJ, Han GY, Kim CW. The reno-protective effect of a phosphoinositide 3-kinase inhibitor wortmannin on streptozotocin-induced proteinuric renal disease rats. Exp Mol Med 2012; 44:45-51. [PMID: 22056625 DOI: 10.3858/emm.2012.44.1.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Diabetic nephropathy (DN) is a progressive kidney disease that is caused by injury to kidney glomeruli. Podocytes are glomerular epithelial cells and play critical roles in the glomerular filtration barrier. Recent studies have shown the importance of regulating the podocyte actin cytoskeleton in early DN. The phosphoinositide 3-kinase (PI3K) inhibitor, wortmannin, simultaneously regulates Rac1 and Cdc42, which destabilize the podocyte actin cytoskeleton during early DN. In this study, in order to evaluate the reno-protective effects of wortmannin in early DN by regulating Rac1 and Cdc42, streptozotocin (STZ)-induced proteinuric renal disease (SPRD) rats were treated with wortmannin. The albuminuria value of the SPRD group was 3.55 ± 0.56 mg/day, whereas wortmannin group was 1.77 ± 0.48 mg/day. Also, the albumin to creatinine ratio (ACR) value of the SPRD group was 53.08 ± 10.82 mg/g, whereas wortmannin group was 20.27 ± 6.41 mg/g. Changes in the expression level of nephrin, podocin and Rac1/Cdc42, which is related to actin cytoskeleton in podocytes, by wortmannin administration were confirmed by Western blotting. The expression levels of nephrin (79.66 ± 0.02), podocin (87.81 ± 0.03) and Rac1/Cdc42 (86.12 ± 0.02) in the wortmannin group were higher than the expression levels of nephrin (55.32 ± 0.03), podocin (53.40 ± 0.06) and Rac1/Cdc42 (54.05 ± 0.04) in the SPRD group. In addition, expression and localization of nephrin, podocin and desmin were confirmed by immunofluorescence. In summary, we found for the first time that wortmannin has a reno-protective effect on SPRD rats during the early DN. The beneficial effects of wortmannin in SPRD rats indicate that this compound could be used to delay the progression of the disease during the early DN stage.
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Affiliation(s)
- Sang Hoon Kim
- School of Life Sciences and Biotechnology Korea University Seoul, Korea
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The ADF/Cofilin-Pathway and Actin Dynamics in Podocyte Injury. Int J Cell Biol 2011; 2012:320531. [PMID: 22190940 PMCID: PMC3235464 DOI: 10.1155/2012/320531] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 09/22/2011] [Accepted: 10/12/2011] [Indexed: 01/15/2023] Open
Abstract
ADF/cofilins are the major regulators of actin dynamics in mammalian cells. The activation of ADF/cofilins is controlled by a variety of regulatory mechanisms. Dysregulation of ADF/cofilin may result in loss of a precisely organized actin cytoskeletal architecture and can reduce podocyte migration and motility. Recent studies suggest that cofilin-1 can be regulated through several extracellular signals and slit diaphragm proteins. Cofilin knockdown and knockout animal models show dysfunction of glomerular barrier and filtration with foot process effacement and loss of secondary foot processes. This indicates that cofilin-1 is necessary for modulating actin dynamics in podocytes. Podocyte alterations in actin architecture may initiate or aid the progression of a large variety of glomerular diseases, and cofilin activity is required for reorganization of an intact filtration barrier. Since almost all proteinuric diseases result from a similar phenotype with effacement of the foot processes, we propose that cofilin-1 is at the centre stage of the development of proteinuria and thus may be an attractive drug target for antiproteinuric treatment strategies.
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30
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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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31
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Palanisamy N, Venkataraman Anuradha C. Soy protein prevents renal damage in a fructose-induced model of metabolic syndrome via inhibition of NF-kB in male rats. Pediatr Nephrol 2011; 26:1809-21. [PMID: 21533627 DOI: 10.1007/s00467-011-1882-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 02/25/2011] [Accepted: 03/17/2011] [Indexed: 12/15/2022]
Abstract
The study determines the effect of soy protein on inflammatory status and expression of nuclear factor-kappa B (NF-κB P(65)) and receptor for advanced glycation end products (RAGE) in a metabolic syndrome (MS) model. MS was induced in adult male rats by feeding them a high fructose diet (60 g/100 g diet). The rats were randomised into six groups by feeding one of the following semi-synthetic diets for 60 days: corn starch (60%) and casein (20%; CCD), fructose (60%) and casein (20%; FCD), fructose (60%) and soy protein (20%; FSD) or corn starch (60%) and soy protein (20%; CSD). The expression of NF-κB P(65), transforming growth factor-β1 (TGF-β1) and RAGE, histochemical localization of α-smooth muscle actin (α-SMA), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) assays, collagen deposition and ultrastructural analysis were performed. FCD rats displayed inflammatory changes and increased expression of growth factors and nuclear factors. FSD rats showed reduction in inflammation, fibrogenesis, collagen deposition, NF-κB activation and mitigated the ultrastructural changes. Soy protein prevents inflammation and early nephropathic changes in the MS model secondary to the attenuation of NF-κB activation.
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Affiliation(s)
- Nallasamy Palanisamy
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalai Nagar, 608 002 Tamil Nadu, India.
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32
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Gigante M, Piemontese M, Gesualdo L, Iolascon A, Aucella F. Molecular and genetic basis of inherited nephrotic syndrome. Int J Nephrol 2011; 2011:792195. [PMID: 21904677 PMCID: PMC3167185 DOI: 10.4061/2011/792195] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/16/2011] [Accepted: 06/16/2011] [Indexed: 12/26/2022] Open
Abstract
Nephrotic syndrome is an heterogeneous disease characterized by increased permeability of the glomerular filtration barrier for macromolecules. Podocytes, the visceral epithelial cells of glomerulus, play critical role in ultrafiltration of plasma and are involved in a wide number of inherited and acquired glomerular diseases. The identification of mutations in nephrin and other podocyte genes as causes of genetic forms of nephrotic syndrome has revealed new important aspects of the pathogenesis of proteinuric kidney diseases and expanded our knowledge of the glomerular biology. Moreover, a novel concept of a highly dynamic slit diaphragm proteins is emerging. The most significant discoveries in our understanding of the structure and function of the glomerular filtration barrier are reviewed in this paper.
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Affiliation(s)
- Maddalena Gigante
- Division of Nephrology, Department of Biomedical Science, University of Foggia, 71121 Foggia, Italy
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Gbadegesin R, Lavin P, Foreman J, Winn M. Pathogenesis and therapy of focal segmental glomerulosclerosis: an update. Pediatr Nephrol 2011; 26:1001-15. [PMID: 21110043 PMCID: PMC3624015 DOI: 10.1007/s00467-010-1692-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 09/28/2010] [Accepted: 10/04/2010] [Indexed: 02/07/2023]
Abstract
Focal and segmental glomerulosclerosis (FSGS) is an important cause of steroid-resistant nephrotic syndrome in adults and children. It is responsible for 5-20% of all cases of end-stage kidney disease (ESKD) in the United States. The pathogenesis of FSGS has not been fully elucidated; however, data from molecular studies of familial cases in the last two decades suggest that FSGS is a defect of the podocyte. The therapeutic agents available for treatment of FSGS are not very effective and only a small percentage of affected individuals will achieve complete remission. Recent data from molecular biology and molecular genetics has provided insight into the mechanisms of action of old agents and also identification of other novel therapeutic targets. This review focuses on recent advances in the molecular pathogenesis of FSGS and currently available therapeutic agents as well as potential novel therapies.
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Affiliation(s)
- Rasheed Gbadegesin
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA.
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34
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Palanisamy N, Kannappan S, Anuradha CV. Genistein modulates NF-κB-associated renal inflammation, fibrosis and podocyte abnormalities in fructose-fed rats. Eur J Pharmacol 2011; 667:355-64. [PMID: 21704028 DOI: 10.1016/j.ejphar.2011.06.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/26/2011] [Accepted: 06/07/2011] [Indexed: 12/21/2022]
Abstract
The study determines the effect of genistein on inflammatory status and expression of nuclear factor-kappa B (NF-κB p65), transforming growth factor-β1 (TGF-β1) and receptor for advanced glycation end products (RAGE) in kidney of fructose-fed rats. Adult male Wistar rats were fed a diet containing either starch or fructose as the source of carbohydrate. Fifteen days later, after confirming the development of insulin resistance in fructose-fed rats, the rats in each dietary group were divided into two and treated with either genistein (1 mg/kg/day) in 30% dimethylsulfoxide (DMSO) or 30% DMSO alone for the next 45 days. The expression of NF-κB P(65), TGF-β1 and RAGE, histochemical localization of α-smooth muscle actin (α-SMA), levels of tumour necrosis factor-α (TNF-α) and interleukin-6(IL-6) and ultrastructural analysis were performed at the end of the experimental period. Fructose-fed rats displayed inflammatory changes in kidney. Increased expression of TGF-β1 and RAGE in cytosol and NF-κB p65 in nuclear fraction were observed. α-SMA expression was higher in fructose-fed rat kidney. Proliferation of connective tissue was evident from increased collagen deposition in perivascular and intraglomerular regions. Administration of genistein to fructose-fed rats reduced inflammation, fibrogenesis and NF-κB activation. Genistein also mitigated the structural changes such as basement membrane thickening, reduction in podocyte number and loss of glomerular filtration barrier integrity. These findings suggest that genistein prevents inflammation, fibrosis and early nephropathic changes in fructose-fed insulin resistant rats secondary to the attenuation of NF-κB activation.
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Affiliation(s)
- Nallasamy Palanisamy
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalai Nagar-608 002, Tamil Nadu, India
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35
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Agrawal S, Guess AJ, Benndorf R, Smoyer WE. Comparison of direct action of thiazolidinediones and glucocorticoids on renal podocytes: protection from injury and molecular effects. Mol Pharmacol 2011; 80:389-99. [PMID: 21636793 DOI: 10.1124/mol.111.071654] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The U.S. Food and Drug Administration-approved thiazolidinediones pioglitazone and rosiglitazone are peroxisome proliferator-activated receptor-γ (PPARγ) agonists developed to control serum glucose in patients with diabetes. They have been found to reduce proteinuria and microalbuminuria in both diabetic nephropathy and nondiabetic glomerulosclerosis. We hypothesized that the renal protective effects of thiazolidinediones result, at least in part, from their direct action on podocytes, similar to glucocorticoids. Treatment with pioglitazone, rosiglitazone, or dexamethasone significantly protected podocytes against puromycin aminonucleoside-induced injury (designed to mimic nephrotic syndrome-related injury), as determined by both cell survival and actin cytoskeletal integrity. Furthermore, we compared the ability of these drugs to modulate key signaling pathways in podocytes that may be critical to their protective effects. Rosiglitazone deactivated the mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinases 1/2, p38 MAPK, and stress-activated protein kinase/c-Jun NH₂-terminal kinase, whereas pioglitazone did not, and dexamethasone deactivated to some extent. Similar to dexamethasone, both thiazolidinediones increased the glucocorticoid receptor phosphorylation, and this response to rosiglitazone and possibly to pioglitazone was PPARγ-dependent. Furthermore, both drugs mimicked or enhanced the effects of dexamethasone on glucocorticoid-responsive genes in a PPARγ- and glucocorticoid receptor-dependent manner. In addition, both thiazolidinediones mimicked dexamethasone-induced effects on calcineurin activity. In summary, thiazolidinediones are able to modulate the glucocorticoid pathway and exert direct protective effects on podocytes, similar to glucocorticoids. This suggests that thiazolidinediones may have potential clinical utility as either primary or adjunctive therapy for nephrotic syndrome or other diseases treated with glucocorticoids. These findings may also lend mechanistic insight into the well established but poorly understood renal protective effects of thiazolidinediones in diabetic nephropathy.
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Affiliation(s)
- Shipra Agrawal
- Center for Clinical and Translational Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
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36
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Pengal R, Guess AJ, Agrawal S, Manley J, Ransom RF, Mourey RJ, Benndorf R, Smoyer WE. Inhibition of the protein kinase MK-2 protects podocytes from nephrotic syndrome-related injury. Am J Physiol Renal Physiol 2011; 301:F509-19. [PMID: 21613416 DOI: 10.1152/ajprenal.00661.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
While mitogen-activated protein kinase (MAPK) activation has been implicated in the pathogenesis of various glomerular diseases, including nephrotic syndrome (NS), its specific role in podocyte injury is not known. We hypothesized that MK-2, a downstream substrate of p38 MAPK, mediates the adverse effects of this pathway and that inhibition of MK-2 would protect podocytes from NS-related injury. Using cultured podocytes, we analyzed 1) the roles of MK-2 and p38 MAPK in puromycin aminonucleoside (PAN)-induced podocyte injury; 2) the ability of specific MK-2 and p38 MAPK inhibitors to protect podocytes against injury; 3) the role of serum albumin, known to induce podocyte injury, in activating p38 MAPK/MK-2 signaling; and 4) the role of p38 MAPK/MK-2 signaling in the expression of Cox-2, an enzyme associated with podocyte injury. Treatment with protein kinase inhibitors specific for both MK-2 (C23, a pyrrolopyridine-type compound) or p38 MAPK (SB203580) reduced PAN-induced podocyte injury and actin cytoskeletal disruption. Both inhibitors reduced baseline podocyte p38 MAPK/MK-2 signaling, as measured by the degree of phosphorylation of HSPB1, a downstream substrate of MK-2, but exhibited disparate effects on upstream signaling. Serum albumin activated p38 MAPK/MK-2 signaling and induced Cox-2 expression, and these responses were blocked by both inhibitors. Given the critical importance of podocyte injury to both NS and other progressive glomerular diseases, these data suggest an important role for p38 MAPK/MK-2 signaling in podocyte injury and identify MK-2 inhibition as a promising potential therapeutic strategy to protect podocytes in various glomerular diseases.
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Affiliation(s)
- Ruma Pengal
- Center for Clinical and Translational Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
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37
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Perysinaki GS, Moysiadis DK, Bertsias G, Giannopoulou I, Kyriacou K, Nakopoulou L, Boumpas DT, Daphnis E. Podocyte main slit diaphragm proteins, nephrin and podocin, are affected at early stages of lupus nephritis and correlate with disease histology. Lupus 2011; 20:781-91. [PMID: 21478284 DOI: 10.1177/0961203310397412] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Renal podocytes and their slit diaphragms ensure the integrity of the renal basement membrane that forms the barrier to urinary protein loss. A putative disruption of the slit diaphragm and its main protein components, nephrin and podocin, may be implicated in the pathogenesis of lupus nephritis (LN). We studied the glomerular protein expression of nephrin and podocin in NZB/W LN mice by Western blot and immunofluorescence; mRNA levels were measured by real-time PCR. Human kidney biopsies of class II (n = 5), IV (n = 4), V (n = 7) LN were evaluated for nephrin expression by immunohistochemistry. Glomerular protein expression of nephrin and podocin were significantly reduced in NZB/W LN, starting from the earlier stages (mild mesangial LN) and becoming pronounced at advanced histological forms (focal and diffuse proliferative LN). Nephrin and podocin mRNA levels were substantially decreased in diffuse proliferative disease. Decreased expression of both proteins correlated with electron microscopy findings of distorted slit diaphragms. In patients with LN, nephrin was decreased particularly in diffuse proliferative LN. The main slit diaphragm proteins, nephrin and podocin, are affected from the earlier stages of LN and their expression correlates with disease histology. Our findings suggest a novel role of podocytes and their structures in immune-mediated nephritis.
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Affiliation(s)
- G S Perysinaki
- Laboratory of Nephrology, Medical Department, University of Crete, Greece
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38
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Kistler AD, Peev V, Forst AL, El Hindi S, Altintas MM, Reiser J. Enzymatic disease of the podocyte. Pediatr Nephrol 2010; 25:1017-23. [PMID: 20130922 PMCID: PMC4109305 DOI: 10.1007/s00467-009-1425-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 11/11/2009] [Accepted: 11/17/2009] [Indexed: 01/08/2023]
Abstract
Proteinuria is an early sign of kidney disease and has gained increasing attention over the past decade because of its close association with cardio-vascular and renal morbidity and mortality. Podocytes have emerged as the cell type that is critical in maintaining proper functioning of the kidney filter. A few genes have been identified that explain genetic glomerular failure and recent insights shed light on the pathogenesis of acquired proteinuric diseases. This review highlights the unique role of the cysteine protease cathepsin L as a regulatory rather than a digestive protease and its action on podocyte structure and function. We provide arguments why many glomerular diseases can be regarded as podocyte enzymatic disorders.
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Affiliation(s)
- Andreas D. Kistler
- Department of Nephrology, University Hospital, Zürich, Switzerland,Miami Institute of Renal Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, 1580 NW 10th Street, Batchelor Bldg. #633A, Miami, FL 33136, USA
| | - Vasil Peev
- Miami Institute of Renal Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, 1580 NW 10th Street, Batchelor Bldg. #633A, Miami, FL 33136, USA
| | - Anna-Lena Forst
- Miami Institute of Renal Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, 1580 NW 10th Street, Batchelor Bldg. #633A, Miami, FL 33136, USA
| | - Shafic El Hindi
- Miami Institute of Renal Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, 1580 NW 10th Street, Batchelor Bldg. #633A, Miami, FL 33136, USA
| | - Mehmet M. Altintas
- Miami Institute of Renal Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, 1580 NW 10th Street, Batchelor Bldg. #633A, Miami, FL 33136, USA
| | - Jochen Reiser
- Miami Institute of Renal Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, 1580 NW 10th Street, Batchelor Bldg. #633A, Miami, FL 33136, USA
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Kim JH, Konieczkowski M, Mukherjee A, Schechtman S, Khan S, Schelling JR, Ross MD, Bruggeman LA, Sedor JR. Podocyte injury induces nuclear translocation of WTIP via microtubule-dependent transport. J Biol Chem 2010; 285:9995-10004. [PMID: 20086015 DOI: 10.1074/jbc.m109.061671] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Podocyte structural and transcriptional phenotype plasticity characterizes glomerular injury. Transcriptional activity of WT1 (Wilm's tumor 1) is required for normal podocyte structure and is repressed by the podocyte adherens junction protein, WTIP (WT1 interacting protein). Here we show that WTIP translocated into podocyte nuclei in lipopolysaccharide (LPS)-treated mice, a model of transient nephrotic syndrome. Cultured podocytes, which stably expressed an epitope-tagged WTIP, were treated with LPS. Imaging and cellular fractionation studies demonstrated that WTIP translocated from podocyte cell contacts into nuclei within 6 h and relocalized to cell contacts within 24 h after LPS treatment. LPS-stimulated WTIP nuclear translocation required JNK activity, which assembled a multiprotein complex of the scaffolding protein JNK-interacting protein 3 and the molecular motor dynein. Intact microtubule networks and dynein activity were necessary for LPS-stimulated WTIP translocation. Podocytes expressing sh-Wtip change morphology and demonstrate altered actin assembly in cell spreading assays. Stress signaling pathways initiate WTIP nuclear translocation, and the concomitant loss of WTIP from cell contacts changes podocyte morphology and dynamic actin assembly, suggesting a mechanism that transmits changes in podocyte morphology to the nucleus.
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Affiliation(s)
- Jane H Kim
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44109
| | - Martha Konieczkowski
- Case Western Reserve University Center for the Study of Kidney Disease and Biology, Cleveland, Ohio 44109
| | - Amitava Mukherjee
- Case Western Reserve University Center for the Study of Kidney Disease and Biology, Cleveland, Ohio 44109
| | - Sam Schechtman
- Case Western Reserve University Center for the Study of Kidney Disease and Biology, Cleveland, Ohio 44109
| | - Shenaz Khan
- Case Western Reserve University Center for the Study of Kidney Disease and Biology, Cleveland, Ohio 44109
| | - Jeffrey R Schelling
- Case Western Reserve University Center for the Study of Kidney Disease and Biology, Cleveland, Ohio 44109; Department of Medicine, MetroHealth System Campus, Cleveland, Ohio 44109
| | - Michael D Ross
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Leslie A Bruggeman
- Case Western Reserve University Center for the Study of Kidney Disease and Biology, Cleveland, Ohio 44109; Department of Medicine, MetroHealth System Campus, Cleveland, Ohio 44109
| | - John R Sedor
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44109; Case Western Reserve University Center for the Study of Kidney Disease and Biology, Cleveland, Ohio 44109; Department of Medicine, MetroHealth System Campus, Cleveland, Ohio 44109.
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40
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Ha TS. High-glucose and advanced glycosylation end products increased podocyte permeability via PI3-K/Akt signaling. J Mol Med (Berl) 2010; 88:391-400. [PMID: 20054520 DOI: 10.1007/s00109-009-0575-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2009] [Revised: 11/07/2009] [Accepted: 12/07/2009] [Indexed: 02/06/2023]
Abstract
Regardless of the underlying disease, the proteinuric condition demonstrates ultrastructural changes in podocytes with retraction and effacement of the highly specialized interdigitating foot processes. To investigate how high-glucose (HG) and advanced glycosylation end products (AGE) induce podocyte phenotypical changes, including quantitative and distributional changes of zonula occludens (ZO)-1 protein and search for the signaling mechanisms, we cultured rat glomerular epithelial cells (GEpC) and mouse podocytes under: (1) normal glucose (5 mM, control); (2) HG (30 mM); (3) AGE-added; or (4) HG plus AGE-added conditions. HG plus AGE increased the permeability of monolayered GEpCs and induced ultrastructural separation between confluent GEpCs. ZO-1 moved to inner actin filament complexes in both AGE- and/or HG by confocal imaging. HG plus AGE-added condition also decreased ZO-1 protein amount and mRNA expression compared to normal glucose or osmotic control conditions. We could also confirm the induction of RAGE (receptor for AGE) and PI3-K/Akt signaling pathway by AGE and HG. In addition, LY294002, a PI3-K inhibitor, could prevent the quantitative and distributional changes of ZO-1 and RAGE and the increased permeability induced by HG and AGE. These findings suggest that diabetic conditions induce the podocyte ZO-1 changes via RAGE and PI3-K/Akt signaling, leading to increased permeability.
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Affiliation(s)
- Tae-Sun Ha
- Department of Pediatrics, College of Medicine, Chungbuk National University, Gaeshin-dong 48, Heungdeok-gu, Cheongju, Chungbuk, 361-240, Korea.
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41
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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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De Muro P, Faedda R, Satta AE, Masala A, Cigni A, Falconi D, Sanna GM, Cherchi GM. Quali-quantitative analysis of urinary glycosaminoglycans for monitoring glomerular inflammatory activity. ACTA ACUST UNITED AC 2009; 41:230-6. [PMID: 17469033 DOI: 10.1080/00365590601017105] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVE A 2-year follow-up study was carried out in patients with IgA nephropathy (IgAN) in order to verify the possible use of quali-quantitative analysis of urinary glycosaminoglycans (GAGs) as a prognostic index of disease and for drug treatment monitoring. MATERIAL AND METHODS Ten patients with IgAN were evaluated at four time points: baseline, and 6, 9 and 24 months later. GAGs were isolated from 24-h urine using ion-exchange chromatography on diethylaminoethyl-Sephacel, and concentrations were expressed as milligrams of hexuronate per gram of creatinine. GAG composition was determined by cellulose acetate electrophoresis and expressed as relative percentages by means of densitometric scanning of Alcian Blue-stained strips. RESULTS The relative content of total low-sulphated chondroitin sulphate species decreased significantly during the study period compared to baseline, whereas the relative percentages of heparan sulphate and chondroitin sulphate increased significantly. Moreover, a significant correlation was noted between the relative contents of urinary GAGs, renal function and inflammation indexes. CONCLUSIONS It is likely that the excretion of various types of GAGs may be related to different glomerular pathophysiological conditions. Therefore, the determination of urinary GAG composition may represent a reliable indicator of disease activity.
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Affiliation(s)
- Pierina De Muro
- Department of Physiological, Biochemical and Cellular Science, University of Sassari, Sassari, Italy
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Park SJ, Lee BH, Kim DJ. Identification of proteins that interact with podocin using the yeast 2-hybrid system. Yonsei Med J 2009; 50:273-9. [PMID: 19430563 PMCID: PMC2678704 DOI: 10.3349/ymj.2009.50.2.273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 08/28/2008] [Accepted: 08/28/2008] [Indexed: 11/27/2022] Open
Abstract
PURPOSE As a membrane protein at the insertion site of the slit diaphragm (SD) complex in podocyte foot processes, podocin has been reported to act as a scaffolding protein required to maintain or regulate the structural integrity of the SD. In order to identify proteins that associate or interact with podocin, we screened a mouse kidney complementary DNA (cDNA) library using a yeast 2-hybrid system. MATERIALS AND METHODS 1) The full-length cDNA of podocin from the mouse kidney was amplified by Polymerase Chain Reaction (PCR), 2) The PCR product was cloned into a pGBKT7 vector, pGBKT7-podocin, 3) After the pGBKT7-podocin was transformed into AH109, the AH109/pGBKT7-podocin product was obtained, 4) The mouse kidney cDNA library was transformed into the AH109/pGBKT7-podocin and screened by selection steps, 5) Next, twelve clones were cultured and isolated, 6) The yeast-purified plasmids were transformed into Escherichia coli (E. coli) by heat shock, and 7) To identify the activation domain (AD)/library inserts, we digested them with Him III, and the fragments were then sequenced. RESULTS 12 positive clones that interacted with podocin were obtained by screening a mouse kidney cDNA library using pGBKT7-podocin. Among them, only 4 clones were found to function at the podocyte where podocin is present. CONCLUSION Additional studies are needed to clarify the role and interaction with podocin and candidates.
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Affiliation(s)
- Soo Jin Park
- Clinical Research Center, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Byung Ha Lee
- Clinical Research Center, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Dae Joong Kim
- Division of Nephrology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Coaxum SD, Garnovskaya MN, Gooz M, Baldys A, Raymond JR. Epidermal growth factor activates Na(+/)H(+) exchanger in podocytes through a mechanism that involves Janus kinase and calmodulin. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1174-81. [PMID: 19341767 DOI: 10.1016/j.bbamcr.2009.03.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 02/28/2009] [Accepted: 03/19/2009] [Indexed: 01/23/2023]
Abstract
Sodium-proton exchanger type 1 (NHE-1) is ubiquitously expressed, is activated by numerous growth factors, and plays significant roles in regulating intracellular pH and cellular volume, proliferation and cytoskeleton. Despite its importance, little is known about its regulation in renal glomerular podocytes. In the current work, we studied the regulation of NHE-1 activity by the epidermal growth factor receptor (EGFR) in cultured podocytes. RT-PCR demonstrated mRNAs for NHE-1 and NHE-2 in differentiated podocytes, as well as for EGFR subunits EGFR/ErbB1, Erb3, and ErbB4. EGF induced concentration-dependent increases in proton efflux in renal podocytes as assessed using a Cytosensor microphysiometer, were diminished in the presence of 5-(N-methyl-N-isobutyl) amiloride or in a sodium-free solution. Furthermore, pharmacological inhibitors of Janus kinase (Jak2) and calmodulin (CaM) attenuated EGF-induced NHE-1 activity. Co-immunoprecipitation studies determined that EGF induced formation of complexes between Jak2 and CaM, as well as between CaM and NHE-1. In addition, EGF increased levels of tyrosine phosphorylation of Jak2 and CaM. The EGFR kinase inhibitor, AG1478, blocked activation of NHE-1, but did not block EGF-induced phosphorylation of Jak2 or CaM. These results suggest that EGF induces NHE-1 activity in podocytes through two pathways: (1) EGF-->EGFR-->Jak2 activation (independent of EGFR tyrosine kinase activity)-->tyrosine phosphorylation of CaM-->CaM binding to NHE-1-->conformational change of NHE-1-->activation of NHE-1; and (2) EGF-->EGFR-->EGFR kinase activation-->association of CaM with NHE-1 (independent of Jak2)-->conformational change of NHE-1-->activation of NHE-1.
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Affiliation(s)
- Sonya D Coaxum
- Medical and Research Services, Ralph H. Johnson VA Medical Center, USA
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Munkert A, Helmchen U, Kemper MJ, Bubenheim M, Stahl RAK, Harendza S. Characterization of the transcriptional regulation of the human MT1-MMP gene and association of risk reduction for focal-segmental glomerulosclerosis with two functional promoter SNPs. Nephrol Dial Transplant 2008; 24:735-42. [PMID: 18927121 DOI: 10.1093/ndt/gfn576] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The matrix metalloproteinase MT1-MMP (MMP-14) is an important player in wound healing, bone development, angiogenesis, inflammation and tumour invasion. MT1-MMP also plays an important role in the development and resolution of experimental kidney diseases. The role of MT1-MMP was investigated for distinction between minimal-change glomerulonephritis (MCGN) and focal-segmental glomerulosclerosis (FSGS) that can sometimes be difficult due to sampling error in renal biopsy. METHODS We defined the transcriptional regulation of the human MT1-MMP and the influence of single nucleotide polymorphisms (SNPs) within its promoter region in renal mesangial cells with reporter gene constructs and gel sift analysis. Genomic DNA from healthy blood donors (n = 500) and from kidney biopsies with defined renal diseases (MCGN: n = 189, FSGS: n = 311) was screened for MT1-MMP promoter SNPs. RESULTS Transcription of MT1-MMP is regulated by two enhancers, an Sp1 binding site and a regulatory region 1 (RR1). RR1 contains an Ets site binding the transcription factors Elf-1 and E1AF but not NFAT. The MT1-MMP promoter contains two SNPs (-378 T/C and -364 G/T) in close vicinity to the RR1. Occurrence of the SNP variant -378 C leads to strong inhibition of nuclear protein binding to the RR1 reducing its enhancer function. Appearance of either variant -378 C or variant -364 T in at least one copy of the MT1-MMP promoter was associated with a significant risk reduction for the development of FSGS (P < 0.048). CONCLUSION Genetic testing for MT1-MMP promoter SNPs could put renal biopsy results into new perspective. An independent study will be required to verify these findings and their possible diagnostic value for differentiation between certain renal diseases.
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Affiliation(s)
- Astrid Munkert
- III Medizinische Klinik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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Hsu HH, Hoffmann S, Endlich N, Velic A, Schwab A, Weide T, Schlatter E, Pavenstädt H. Mechanisms of angiotensin II signaling on cytoskeleton of podocytes. J Mol Med (Berl) 2008; 86:1379-94. [PMID: 18773185 DOI: 10.1007/s00109-008-0399-y] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 07/12/2008] [Accepted: 08/01/2008] [Indexed: 01/16/2023]
Abstract
Podocytes are significant in establishing the glomerular filtration barrier. Sustained rennin-angiotensin system (RAS) activation is crucial in the pathogenesis of podocyte injury and causes proteinuria. This study demonstrates that angiotensin II (Ang II) caused a reactive oxygen species (ROS)-dependent rearrangement of cortical F-actin and a migratory phenotype switch in cultured mouse podocytes with stable Ang II type 1 receptor (AT1R) expression. Activated small GTPase Rac-1 and phosphorylated ezrin/radixin/moesin (ERM) proteins provoked Ang II-induced F-actin cytoskeletal remodeling. This work also shows increased expression of Rac-1 and phosphorylated ERM proteins in cultured podocytes, and in glomeruli of podocyte-specific AT1R transgenic rats (Neph-hAT1 TGRs). The free radical scavenger DMTU eliminated Ang II-induced cell migration, ERM protein phosphorylation and cortical F-actin remodeling, indicating that ROS mediates the influence of Rac-1 on podocyte AT1R signaling. Heparin, a potent G-coupled protein kinase 2 inhibitor, was found to abolish ERM protein phosphorylation and cortical F-actin ring formation in Ang II-treated podocytes, indicating that phosphorylated ERM proteins are the cytoskeletal effector in AT1R signaling. Moreover, Ang II stimulation triggered down-regulation of alpha actinin-4 and reduced focal adhesion expression in podocytes. Signaling inhibitor assay of Ang II-treated podocytes reveals that Rac-1, RhoA, and F-actin reorganization were involved in expressional regulation of alpha actinin-4 in AT1R signaling. With persistent RAS activation, the Ang II-induced phenotype shifts from being dynamically stable to adaptively migratory, which may eventually exhaust podocytes with a high actin cytoskeletal turnover, causing podocyte depletion and focal segmental glomerulosclerosis.
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Affiliation(s)
- Hsiang-Hao Hsu
- Department of Medicine D, Division of General Internal Medicine and Nephrology, University Hospital Muenster, Albert-Schweitzer-Str. 33, 48149 Muenster, Germany
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Otaki Y, Miyauchi N, Higa M, Takada A, Kuroda T, Gejyo F, Shimizu F, Kawachi H. Dissociation of NEPH1 from nephrin is involved in development of a rat model of focal segmental glomerulosclerosis. Am J Physiol Renal Physiol 2008; 295:F1376-87. [PMID: 18715943 DOI: 10.1152/ajprenal.00075.2008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a disease showing severe proteinuria, and the disease progresses to end-stage kidney failure in many cases. However, the pathogenic mechanism of FSGS is not well understood. The slit diaphragm (SD), which bridges the neighboring foot processes of glomerular epithelial cells, is understood to function as a barrier of the glomerular capillary wall. To investigate the role of SD dysfunction in the development of FSGS, we analyzed the expression of SD-associated molecules in rat adriamycin-induced nephropathy, a mimic of FSGS. The staining of the SD molecules nephrin, podocin, and NEPH1 had already shifted to a discontinuous dotlike pattern at the initiation phase of the disease, when neither proteinuria nor any morphological alterations were detected yet. The alteration of NEPH1 expression was the most evident among the molecules examined, and NEPH1 was dissociated from nephrin at the initiation phase. On day 28, when severe proteinuria was detected and sclerotic changes were already observed, alteration of the expressions of nephrin, podocin, and NEPH1 worsened, but no alteration in the expression of other SD-associated molecules or other podocyte molecules was detected. It is postulated that the dissociation of NEPH1 from nephrin initiates proteinuria and that the SD alteration restricted in these molecules plays a critical role in the development of sclerotic changes in FSGS.
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Affiliation(s)
- Yasuhiro Otaki
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Niigata, 951-8510, Japan
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Lu C, Ren W, Su XM, Chen JQ, Wu SH, Guo XR, Huang SM, Chen LH, Zhou GP. CREB and Sp1 regulate the human CD2AP gene promoter activity in renal tubular epithelial cells. Arch Biochem Biophys 2008; 474:143-9. [PMID: 18396147 DOI: 10.1016/j.abb.2008.03.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 03/24/2008] [Indexed: 11/28/2022]
Abstract
The human CD2-associated protein (CD2AP) is involved in several molecular signaling pathways and is an important factor responsible for nephrotic syndrome. Here we report the identification of the transcription start point and promoter region of the human CD2AP gene in renal tubular epithelial cells. With luciferase assays and deletion analysis, we found that the region between -558 and -1bp ahead of the transcription start point is indispensable for the promoter activity of the human CD2AP gene. A CREB site and two Sp1 sites were essential for maintaining the basal transcriptional activity of the human CD2AP promoter. Overexpression of phosphorylated CREB and Sp1 transactivated the human CD2AP promoter, whereas small interfering RNA-mediated blockage of CREB and Sp1 genes expressions inhibited markedly its activity. These findings provide the first analysis of the human CD2AP gene promoter and demonstrate that not only CREB but also Sp1 plays a critical role in regulating basal CD2AP promoter activity in renal tubular epithelial cells.
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Affiliation(s)
- Chao Lu
- Department of Pediatrics, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, People's Republic of China
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ASANUMA KATSUHIKO, YANAGIDA-ASANUMA ETSUKO, TAKAGI MIYUKI, KODAMA FUMIKO, TOMINO YASUHIKO. The role of podocytes in proteinuria. Nephrology (Carlton) 2007; 12 Suppl 3:S15-20. [DOI: 10.1111/j.1440-1797.2007.00876.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Awad AS, Rouse M, Liu L, Vergis AL, Rosin DL, Linden J, Sedor JR, Okusa MD. Activation of adenosine 2A receptors preserves structure and function of podocytes. J Am Soc Nephrol 2007; 19:59-68. [PMID: 18045850 DOI: 10.1681/asn.2007030276] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Adenosine 2A receptor (A(2A)R) activation was recently shown to be renoprotective in diabetic nephropathy. A(2A)R are found in glomeruli and have been shown to associate with the podocyte cytoskeletal protein alpha-actinin-4, but the effect of their activation on podocyte structure and function is unknown. Podocyte injury was induced in C57BL/6 mice with puromycin aminonucleoside, and the selective A(2A)R agonist ATL313 was found to attenuate the resulting albuminuria and foot process fusion. The selective A(2A)R antagonist ZM241385 reversed the effects of ATL313. In vitro, A(2A)R mRNA and protein were expressed in a conditionally immortalized podocyte cell line, and A(2A)R-like immunoreactivity co-localized with the actin cytoskeleton. Treatment with ATL313 also blocked the increased podocyte permeability to albumin and disruption of the actin cytoskeleton that accompanied puromycin aminonucleoside-induced injury in vitro. ATL313 was ineffective, however, in the presence of the A(2A)R antagonist and in A(2A)R-deficient podocytes. It was concluded that A(2A)R activation reduces glomerular proteinuria, at least in part, by preserving the normal structure of podocyte foot processes, slit diaphragms, and actin cytoskeleton.
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Affiliation(s)
- Alaa S Awad
- Division of Nephrology, Box 133, University of Virginia Health System, Charlottesville, VA 22908, USA
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