1
|
Zeng Y, Xiong C, Chen Y, Yang C, Li Q. Effects and mechanism of Rictor interference in podocyte injury induced by high glucose. Exp Ther Med 2023; 26:473. [PMID: 37753299 PMCID: PMC10518650 DOI: 10.3892/etm.2023.12172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 07/07/2023] [Indexed: 09/28/2023] Open
Abstract
Rapamycin-insensitive companion of mTOR (Rictor) is a critical effector of mTOR protein complex 2 (mTORC2). The aim of the present study was to investigate the effect of Rictor in the mTORC2 signaling pathway in high glucose (HG)-induced diabetic podocyte injury by silencing the expression of Rictor. In the present study, mouse podocytes were treated with glucose (150 mM) and mannitol (200 mM), the Rictor gene was silenced using small interfering RNA (siRNA). Apoptosis was detected by flow cytometry, whereas podocyte cytoskeletal protein expression was detected by western blotting (WB) and immunofluorescence staining. The results demonstrated that, compared with that in the control group, the podocyte apoptotic rate was significantly increased in the mannitol group (negative group) and the groups that were treated with glucose (model groups). The podocyte apoptotic rate in the model + Rictor siRNA group was significantly decreased compared with that in the negative, model and the model glucose + siRNA negative control (NC) groups. WB indicated that the protein expression levels of podocalyxin and synaptopodin were reduced in the model and model + siRNA NC groups compared with those in the normal control and negative groups. Additionally, the protein expression levels of α-smooth muscle actin (α-SMA) and P-AKT/AKT were increased in the model and model + siRNA NC groups compared with the those in control and negative groups. Compared with those the model and model + siRNA NC groups, the protein expression levels of podocalyxin and synaptopodin were increased, whilst those of the α-SMA and P-AKT/AKT proteins were decreased, in the model + Rictor siRNA group. Results from immunofluorescence analysis were basically consistent with those of WB. Therefore, results of the present study suggest that silencing of the Rictor gene may reduce the damage to podocytes induced by HG, such that the Rictor/mTORC2 signaling pathway may be involved in the remodeling of podocyte actin cytoskeletal in diabetes.
Collapse
Affiliation(s)
- Yan Zeng
- Department of Nephrology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Changbin Xiong
- Department of Nephrology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Yinxiang Chen
- Department of Nephrology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Chunyun Yang
- Department of Nephrology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Qiuyue Li
- Department of Nephrology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| |
Collapse
|
2
|
Ai Z, Wang M, Zhou Y, Yuan D, Jian Q, Wu S, Liu B, Yang Y. Deciphering the pharmacological mechanisms of Rostellularia procumbens (L) Nees. Extract alleviates adriamycin-induced nephropathy in vivo and in vitro. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 113:154736. [PMID: 36907143 DOI: 10.1016/j.phymed.2023.154736] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 02/09/2023] [Accepted: 02/26/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Rostellularia procumbens (L) Nees. is an effective traditional Chinese herbal medicine for the treatment of patients with chronic glomerulonephritis (CGN) in the clinic. However, the underlying molecular mechanisms need further elucidation. PURPOSE This study aims to investigate the renoprotective mechanisms of n-butanol extract from Rostellularia procumbens (L) Nees. (J-NE) in vivo and in vitro. METHODS The components of J-NE were analyzed by UPLC-MS/MS. In vivo, the nephropathy model was induced in mice by tail vein injection with adriamycin (10 mg·kg-1), and mice were treated with vehicle or J-NE or benazepril by daily gavage. In vitro, MPC5 cells exposed to adriamycin (0.3 μg/ml) were treated with J-NE. The effects of J-NE inhibit podocyte apoptosis and protect against adriamycin-induced nephropathy were determined by Network pharmacology, RNA-seq, qPCR, ELISA, immunoblotting, flow cytometry, and TUNEL assay, according to the experimental protocols. RESULT The results showed that treatment significantly improved ADR-induced renal pathological changes, and the therapeutic mechanism of J-NE was related to the inhibition of podocyte apoptosis. Further molecular mechanism studies found that J-NE inhibited inflammation, increase the proteins expression levels of Nephrin and Podocin, reduce TRPC6 and Desmin expression levels and calcium ion levels in podocytes, and decrease the proteins expression levels of PI3K, p-PI3K, Akt and p-Akt to attenuated apoptosis. Furthermore, 38 compounds of J-NE were identified. CONCLUSION J-NE exerted the renoprotective effects by inhibiting podocyte apoptosis, which provides effective evidence for the treatment of J-NE targeting renal injury in CGN.
Collapse
Affiliation(s)
- Zhongzhu Ai
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China; Key Laboratory of Traditional Chinese Medicine Resources and Chemistry of Hubei Province, Wuhan 430065, China; Modern Engineering Research Center of Traditional Chinese Medicine and Ethnic Medicine of Hubei Province, Wuhan 430065, China
| | - Mengfan Wang
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China; Key Laboratory of Traditional Chinese Medicine Resources and Chemistry of Hubei Province, Wuhan 430065, China; Modern Engineering Research Center of Traditional Chinese Medicine and Ethnic Medicine of Hubei Province, Wuhan 430065, China
| | - Yi Zhou
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China
| | - Dongfeng Yuan
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China
| | - Qiuyuan Jian
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China
| | - Songtao Wu
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China
| | - Bo Liu
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China; Key Laboratory of Traditional Chinese Medicine Resources and Chemistry of Hubei Province, Wuhan 430065, China; Modern Engineering Research Center of Traditional Chinese Medicine and Ethnic Medicine of Hubei Province, Wuhan 430065, China
| | - Yanfang Yang
- Faculty of Pharmacy, Hubei University of Chinese Medicine, Wuhan 430065, China; Key Laboratory of Traditional Chinese Medicine Resources and Chemistry of Hubei Province, Wuhan 430065, China; Modern Engineering Research Center of Traditional Chinese Medicine and Ethnic Medicine of Hubei Province, Wuhan 430065, China.
| |
Collapse
|
3
|
Susa K, Kobayashi K, Galichon P, Matsumoto T, Tamura A, Hiratsuka K, Gupta NR, Yazdi IK, Bonventre JV, Morizane R. ATP/ADP biosensor organoids for drug nephrotoxicity assessment. Front Cell Dev Biol 2023; 11:1138504. [PMID: 36936695 PMCID: PMC10017499 DOI: 10.3389/fcell.2023.1138504] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/15/2023] [Indexed: 03/06/2023] Open
Abstract
Drug nephrotoxicity is a common healthcare problem in hospitalized patients and a major limitation during drug development. Multi-segmented kidney organoids derived from human pluripotent stem cells may complement traditional cell culture and animal experiments for nephrotoxicity assessment. Here we evaluate the capability of kidney organoids to investigate drug toxicity in vitro. Kidney organoids express renal drug transporters, OAT1, OAT3, and OCT2, while a human proximal tubular cell line shows the absence of OAT1 and OAT3. Tenofovir and aristolochic acid (AA) induce proximal tubular injury in organoids which is ameliorated by an OAT inhibitor, probenecid, without damage to podocytes. Similarly, cisplatin causes proximal tubular damage that can be relieved by an OCT inhibitor, cimetidine, collectively suggesting the presence of functional OATs and OCTs in organoid proximal tubules. Puromycin aminonucleoside (PAN) induced segment-specific injury in glomerular podocytes in kidney organoids in the absence of tubular injury. Reporter organoids were generated with an ATP/ADP biosensor, which may be applicable to high-throughput screening in the future. In conclusion, the kidney organoid is a useful tool for toxicity assessment in the multicellular context and may contribute to nephrotoxicity assessment during drug development.
Collapse
Affiliation(s)
- Koichiro Susa
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- Department of Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kenichi Kobayashi
- Harvard Medical School, Boston, MA, United States
- Massachusetts General Hospital, Boston, MA, United States
| | - Pierre Galichon
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
| | - Takuya Matsumoto
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States
| | - Akitoshi Tamura
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
| | - Ken Hiratsuka
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- Massachusetts General Hospital, Boston, MA, United States
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States
| | - Navin R. Gupta
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- Massachusetts General Hospital, Boston, MA, United States
| | - Iman K. Yazdi
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States
- Division of Engineering in Medicine, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard-MIT Division of Health Sciences &Technology, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Joseph V. Bonventre
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- Division of Engineering in Medicine, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard-MIT Division of Health Sciences &Technology, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Ryuji Morizane
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- Massachusetts General Hospital, Boston, MA, United States
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States
- Harvard Stem Cell Institute, Cambridge, MA, United States
| |
Collapse
|
4
|
Dong QQ, Li ZF, Zhang H, Shu HP, Tu YC, Liao QQ, Yao LJ. Serum and Glucocorticoid-Inducible Kinase 3/Nedd4-2 Signaling Pathway Participates in Podocyte Injury by Regulating the Stability of Nephrin. Front Physiol 2022; 12:810473. [PMID: 35126185 PMCID: PMC8811367 DOI: 10.3389/fphys.2021.810473] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 12/13/2021] [Indexed: 11/26/2022] Open
Abstract
Serum and glucocorticoid-inducible kinase 3 (SGK3) is involved in maintaining podocyte function by regulating the protein levels of podocin and CD2-associated protein. Nephrin is also one of the slit diaphragm proteins of podocytes, but whether SGK3 participates in podocyte injury by regulating the levels of nephrin remains unclear. In this study, we focused on whether SGK3 affects nephrin levels and the mechanisms involved in the same. In the kidneys of adriamycin (ADR)-induced podocyte injury mouse model, the protein levels of SGK3 and nephrin were significantly decreased. Furthermore, the expression of SGK3 was negatively correlated with the output of proteinuria, and positively correlated with the levels of nephrin. In ADR-treated conditionally immortalized mouse podocyte cells (MPCs), the protein levels of nephrin and SGK3 were inhibited, while the constitutive expression of SGK3 reversed the ADR-induced decline in nephrin protein levels. Furthermore, ADR treatment or SGK3 inactivation enhanced the ubiquitin-proteasome degradation of nephrin in MPCs, and dramatically activated downstream effector proteins of SGK3, neural precursor cells expressing developmentally downregulated protein 4 subtype 2 (Nedd4-2) and glycogen synthase kinase-3 β (GSK3β). Similarly, Nedd4-2 or GSK3β overexpression resulted in increased activity of Nedd4-2 or GSK3β, and significantly downregulated nephrin levels. Interestingly, ubiquitin-mediated protein degradation of nephrin was regulated by Nedd4-2, rather than by GSK3β. In summary, SGK3 inactivation downregulated the levels of nephrin by increasing Nedd4-2 and GSK3β activity in ADR-induced podocyte injury model; in particular, the SGK3/Nedd4-2 signaling pathway was found to be involved in ubiquitin-mediated proteasome degradation of nephrin.
Collapse
Affiliation(s)
- Qing-Qing Dong
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zi-Fang Li
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Blood Purification Center, Hubei No. 3 People’ Hospital of Jianghan University, Wuhan, China
| | - Hui Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hua-Pan Shu
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu-Chi Tu
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qian-Qian Liao
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li-Jun Yao
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Li-Jun Yao,
| |
Collapse
|
5
|
Zhang H, Lin L, Liu J, Pan L, Lin Z, Zhang M, Zhang J, Cao Y, Zhu J, Zhang R. Phase Separation of MAGI2-Mediated Complex Underlies Formation of Slit Diaphragm Complex in Glomerular Filtration Barrier. J Am Soc Nephrol 2021; 32:1946-1960. [PMID: 34330769 PMCID: PMC8455267 DOI: 10.1681/asn.2020111590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/22/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Slit diaphragm is a specialized adhesion junction between the opposing podocytes, establishing the final filtration barrier to urinary protein loss. At the cytoplasmic insertion site of each slit diaphragm there is an electron-dense and protein-rich cellular compartment that is essential for slit diaphragm integrity and signal transduction. Mutations in genes that encode components of this membrane-less compartment have been associated with glomerular diseases. However, the molecular mechanism governing formation of compartmentalized slit diaphragm assembly remains elusive. METHODS We systematically investigated the interactions between key components at slit diaphragm, such as MAGI2, Dendrin, and CD2AP, through a combination of biochemical, biophysical, and cell biologic approaches. RESULTS We demonstrated that MAGI2, a unique MAGUK family scaffold protein at slit diaphragm, can autonomously undergo liquid-liquid phase separation. Multivalent interactions among the MAGI2-Dendrin-CD2AP complex drive the formation of the highly dense slit diaphragm condensates at physiologic conditions. The reconstituted slit diaphragm condensates can effectively recruit Nephrin. A nephrotic syndrome-associated mutation of MAGI2 interfered with formation of the slit diaphragm condensates, thus leading to impaired enrichment of Nephrin. CONCLUSIONS Key components at slit diaphragm (e.g., MAGI2 and its complex) can spontaneously undergo phase separation. The reconstituted slit diaphragm condensates can be enriched in adhesion molecules and cytoskeletal adaptor proteins. Therefore, the electron-dense slit diaphragm assembly might form via phase separation of core components of the slit diaphragm in podocytes.
Collapse
Affiliation(s)
- Haijiao Zhang
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Lin Lin
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Jianping Liu
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lifeng Pan
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhijie Lin
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China,School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Jiong Zhang
- School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Ying Cao
- School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jinwei Zhu
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Rongguang Zhang
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| |
Collapse
|
6
|
Ahmadi A, Moghadasali R, Ezzatizadeh V, Taghizadeh Z, Nassiri SM, Asghari-Vostikolaee MH, Alikhani M, Hadi F, Rahbarghazi R, Yazdi RS, Baharvand H, Aghdami N. Transplantation of Mouse Induced Pluripotent Stem Cell-Derived Podocytes in a Mouse Model of Membranous Nephropathy Attenuates Proteinuria. Sci Rep 2019; 9:15467. [PMID: 31664077 PMCID: PMC6820764 DOI: 10.1038/s41598-019-51770-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 09/26/2019] [Indexed: 12/31/2022] Open
Abstract
Injury to podocytes is a principle cause of initiation and progression of both immune and non-immune mediated glomerular diseases that result in proteinuria and decreased function of the kidney. Current advances in regenerative medicine shed light on the therapeutic potential of cell-based strategies for treatment of such disorders. Thus, there is hope that generation and transplantation of podocytes from induced pluripotent stem cells (iPSCs), could potentially be used as a curative treatment for glomerulonephritis caused by podocytes injury and loss. Despite several reports on the generation of iPSC-derived podocytes, there are rare reports about successful use of these cells in animal models. In this study, we first generated a model of anti-podocyte antibody-induced heavy proteinuria that resembled human membranous nephropathy and was characterized by the presence of sub-epithelial immune deposits and podocytes loss. Thereafter, we showed that transplantation of functional iPSC-derived podocytes following podocytes depletion results in recruitment of iPSC-derived podocytes within the damaged glomerulus, and leads to attenuation of proteinuria and histological alterations. These results provided evidence that application of iPSCs-derived renal cells could be a possible therapeutic strategy to favorably influence glomerular diseases outcomes.
Collapse
Affiliation(s)
- Amin Ahmadi
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Reza Moghadasali
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Vahid Ezzatizadeh
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
- Medical Genetics Department, Medical Laboratory Center, Royesh Medical Group, Tehran, Iran
| | - Zeinab Taghizadeh
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Seyed Mahdi Nassiri
- Department of Clinical Pathology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | | | - Mehdi Alikhani
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Fatemeh Hadi
- Department of Brain and Cognitive Sciences, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Reza Rahbarghazi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Reza Salman Yazdi
- Department of Andrology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Hossein Baharvand
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran.
- Department of Developmental Biology, University of Science and Culture, Tehran, Iran.
| | - Nasser Aghdami
- Department of Regenerative Medicine, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran.
| |
Collapse
|
7
|
Asada Y, Takayanagi T, Kawakami T, Tomatsu E, Masuda A, Yoshino Y, Sekiguchi-Ueda S, Shibata M, Ide T, Niimi H, Yaoita E, Seino Y, Sugimura Y, Suzuki A. Risedronate Attenuates Podocyte Injury in Phosphate Transporter-Overexpressing Rats. Int J Endocrinol 2019; 2019:4194853. [PMID: 31772574 PMCID: PMC6854176 DOI: 10.1155/2019/4194853] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 08/29/2019] [Indexed: 01/01/2023] Open
Abstract
Osteoporosis patients with chronic kidney disease (CKD) are becoming common in our superaging society. Renal dysfunction causes phosphorus accumulation in the circulating plasma and leads to the development of CKD-mineral bone disorder (MBD). We have previously reported that type III Pi transporter-overexpressing transgenic (Pit-1 TG) rats manifest phosphate (Pi)-dependent podocyte injury. In the present study, we explored the effect of risedronate on Pi-induced podocyte injury in vivo. Pit-1 TG rats and wild-type rats at 5 weeks old were divided into a risedronate-treated group and an untreated group. We subcutaneously administered 5 μg/kg body weight of risedronate or saline twice a week during the experimental period. Risedronate did not alter serum creatinine levels at 5, 8, and 12 weeks of age. However, electron microscopy images showed that thickening of the glomerular basement membrane was improved in the risedronate treatment group. Furthermore, immunostaining for podocyte injury markers revealed that both desmin- and connexin43-positive areas were smaller in the risedronate-treated group than in the untreated group, suggesting that bisphosphonates could rescue Pi-induced podocyte injury. In conclusion, our findings suggest that risedronate could maintain glomerular barrier function by rescuing Pi-induced podocyte injury.
Collapse
Affiliation(s)
- Yohei Asada
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Takeshi Takayanagi
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Tsukasa Kawakami
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Eisuke Tomatsu
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Atsushi Masuda
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yasumasa Yoshino
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Sahoko Sekiguchi-Ueda
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Megumi Shibata
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Tomihiko Ide
- Joint Research Support Promotion Facility, Center for Research Promotion and Support, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Hajime Niimi
- Department of Anatomy, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Eishin Yaoita
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 950-2102, Japan
| | - Yusuke Seino
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yoshihisa Sugimura
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Atsushi Suzuki
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| |
Collapse
|
8
|
Husain S, Ginawi I, Bashir AI, Kfoury H, Al Johani TE, Hagar H, Raddaoui L, Al Ghonaim M, Alsuwaida A. Focal and segmental glomerulosclerosis in murine models: a histological and ultrastructural characterization with immunohistochemistry correlation of glomerular CD44 and WT1 expression. Ultrastruct Pathol 2018; 42:430-439. [PMID: 30285525 DOI: 10.1080/01913123.2018.1501125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AIM Focal segmental glomerulosclerosis (FSGS) is a common progressive chronic renal disease. Podocyte injury and loss are the postulated pivotal events that trigger FSGS. In this study, the authors aim to examine the evolution of FSGS in murine models histologically, ultrastructurally and immunohistochemically with special emphasis on podocytes and parietal epithelial cells (PECs). MATERIAL AND METHODS FSGS resembling primary FSGS in humans was initiated in Wistar rats using intravenous Adriamycin injections. Blood and urine analysis were performed at 0, 8, and 12 weeks. Both the control kidneys and the test kidneys were harvested at 8 and 12 weeks, examined histologically and ultrastructurally and the findings correlated with the glomerular expression of immunostains specific for podocytes (WT-1) and for activated PECs (CD44). RESULTS FSGS developed in both 8 and 12 weeks test groups showing progressive proteinuria, podocytopathy and segmental glomerular scarring. There was a decrease in the glomerular expression of WT-1 with a concurrent increase in the glomerular expression of CD44, indicating podocyte loss with synchronous increase in activated PECs. The evolving FSGS correlated negatively with podocytes and positively with activated PECs. CONCLUSION Our study shows that with podocyte injury there is podocyte effacement and loss, proteinuria, glomerular segmental adhesion and scarring, all culminating in FSGS. In addition, there is activation, hyperplasia and hypertrophy of PECs. This demonstrates that both podocyte loss and PEC activation promote FSGS. Our findings are consistent with recent investigations. More studies are required to further understand the role of these cells in the evolution of FSGS and subsequently introduce new targeted treatment modalities.
Collapse
Affiliation(s)
- Sufia Husain
- a Department of Pathology , College of Medicine, King Saud University , Riyadh , Saudi Arabia
| | - Ibrahim Ginawi
- b Department of Family and Community Medicine , College of Medicine, University of Hail , Hail , Saudi Arabia
| | | | - Hala Kfoury
- a Department of Pathology , College of Medicine, King Saud University , Riyadh , Saudi Arabia
| | - Tariq Eid Al Johani
- a Department of Pathology , College of Medicine, King Saud University , Riyadh , Saudi Arabia
| | - Hanan Hagar
- d Department of Pharmacology , College of Medicine, King Saud University , Riyadh , Saudi Arabia
| | - Lama Raddaoui
- e Intern , College of Medicine, King Faisal University , Riyadh , Saudi Arabia
| | - Mohammed Al Ghonaim
- f Department of Medicine and Nephrology , College of Medicine, King Saud University , Riyadh , Saudi Arabia
| | - Abdulkareem Alsuwaida
- f Department of Medicine and Nephrology , College of Medicine, King Saud University , Riyadh , Saudi Arabia
| |
Collapse
|
9
|
Hosoe-Nagai Y, Hidaka T, Sonoda A, Sasaki Y, Yamamoto-Nonaka K, Seki T, Asao R, Tanaka E, Trejo JAO, Kodama F, Takagi M, Tada N, Ueno T, Nishinakamura R, Tomino Y, Asanuma K. Re-expression of Sall1 in podocytes protects against adriamycin-induced nephrosis. J Transl Med 2017; 97:1306-1320. [PMID: 28759006 DOI: 10.1038/labinvest.2017.69] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 04/26/2017] [Accepted: 05/01/2017] [Indexed: 12/12/2022] Open
Abstract
The highly conserved spalt (sal) gene family members encode proteins characterized by multiple double zinc finger motifs of the C2H2 type. Humans and mice each have four known Sal-like genes (SALL1-4 in humans and Sall1-4 in mice). Sall1 is known to have a crucial role in kidney development. To explore the significance of Sall1 in differentiated podocytes, we investigated podocyte-specific Sall1-deficient mice (Sall1 KOp°d°/p°d°) using a podocin-Cre/loxP system and siRNA Sall1 knockdown (Sall1 KD) podocytes. Under physiological conditions, Sall1 KOp°d°/p°d° mice exhibited no proteinuria during their lifetime, but foot-process effacement was detected in some of the podocytes. To elucidate the role of Sall1 in injured podocytes, we used an adriamycin (ADR)-induced model of nephrosis and glomerulosclerosis. Surprisingly, the expression of Sall1 was elevated in control mice on day 14 after ADR injection. On day 28 after ADR injection, Sall1 KOp°d°/p°d° mice exhibited significantly higher levels of proteinuria and higher numbers of sclerotic glomeruli. Differentiated Sall1 KD podocytes showed a loss of synaptopodin, suppressed stress fiber formation, and, ultimately, impaired directed cell migration. In addition, the loss of Sall1 increased the number of apoptotic podocytes following ADR treatment. These results indicated that Sall1 has a protective role in podocytes; thus, we investigated the endoplasmic reticulum stress marker GRP78. GRP78 expression was higher in ADR-treated Sall1 KOp°d°/p°d° mice than in control mice. Sall1 appeared to influence the expression of GRP78 in injured podocytes. These results suggest that Sall1 is associated with actin reorganization, endoplasmic reticulum stress, and apoptosis in injured podocytes. These protective aspects of Sall1 re-expression in injured podocytes may have the potential to reduce apoptosis and possibly glomerulosclerosis.
Collapse
Affiliation(s)
- Yoshiko Hosoe-Nagai
- 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
| | - Ayano Sonoda
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Yu Sasaki
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Kanae Yamamoto-Nonaka
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan.,Laboratory for Kidney Research (TMK project), Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Takuto Seki
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan.,Laboratory for Kidney Research (TMK project), Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Rin Asao
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan.,Laboratory for Kidney Research (TMK project), Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Eriko Tanaka
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan.,Department of Pediatrics, Tokyo Medical and Dental University, Tokyo, Japan
| | - Juan Alejandro Oliva Trejo
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan.,Laboratory for Kidney Research (TMK project), Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Fumiko Kodama
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Miyuki Takagi
- Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Nobuhiro Tada
- Atopy Research Center, Juntendo University School of Medicine, Tokyo, Japan
| | - Takashi Ueno
- Laboratory of Proteomics and Medical Science, Research Support Center, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Ryuichi Nishinakamura
- Department of Kidney Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Yasuhiko Tomino
- 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.,Laboratory for Kidney Research (TMK project), Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| |
Collapse
|
10
|
Rao J, Ashraf S, Tan W, van der Ven AT, Gee HY, Braun DA, Fehér K, George SP, Esmaeilniakooshkghazi A, Choi WI, Jobst-Schwan T, Schneider R, Schmidt JM, Widmeier E, Warejko JK, Hermle T, Schapiro D, Lovric S, Shril S, Daga A, Nayir A, Shenoy M, Tse Y, Bald M, Helmchen U, Mir S, Berdeli A, Kari JA, El Desoky S, Soliman NA, Bagga A, Mane S, Jairajpuri MA, Lifton RP, Khurana S, Martins JC, Hildebrandt F. Advillin acts upstream of phospholipase C ϵ1 in steroid-resistant nephrotic syndrome. J Clin Invest 2017; 127:4257-4269. [PMID: 29058690 DOI: 10.1172/jci94138] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 09/19/2017] [Indexed: 11/17/2022] Open
Abstract
Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of chronic kidney disease. Here, we identified recessive mutations in the gene encoding the actin-binding protein advillin (AVIL) in 3 unrelated families with SRNS. While all AVIL mutations resulted in a marked loss of its actin-bundling ability, truncation of AVIL also disrupted colocalization with F-actin, thereby leading to impaired actin binding and severing. Additionally, AVIL colocalized and interacted with the phospholipase enzyme PLCE1 and with the ARP2/3 actin-modulating complex. Knockdown of AVIL in human podocytes reduced actin stress fibers at the cell periphery, prevented recruitment of PLCE1 to the ARP3-rich lamellipodia, blocked EGF-induced generation of diacylglycerol (DAG) by PLCE1, and attenuated the podocyte migration rate (PMR). These effects were reversed by overexpression of WT AVIL but not by overexpression of any of the 3 patient-derived AVIL mutants. The PMR was increased by overexpression of WT Avil or PLCE1, or by EGF stimulation; however, this increased PMR was ameliorated by inhibition of the ARP2/3 complex, indicating that ARP-dependent lamellipodia formation occurs downstream of AVIL and PLCE1 function. Together, these results delineate a comprehensive pathogenic axis of SRNS that integrates loss of AVIL function with alterations in the action of PLCE1, an established SRNS protein.
Collapse
Affiliation(s)
- Jia Rao
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Medicine, Nephrology, Children's Hospital of Fudan University, Shanghai, China
| | - Shazia Ashraf
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Biosciences, Jamia Millia Islamia, New Delhi, India
| | - Weizhen Tan
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Amelie T van der Ven
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Heon Yung Gee
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Daniela A Braun
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Krisztina Fehér
- NMR and Structure Analysis Group, Department of Organic and Macromolecular Chemistry, University of Gent, Gent, Belgium
| | - Sudeep P George
- Department of Biology and Biochemistry, University of Houston, Houston,Texas, USA
| | | | - Won-Il Choi
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Tilman Jobst-Schwan
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Ronen Schneider
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Johanna Magdalena Schmidt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Eugen Widmeier
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Jillian K Warejko
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Tobias Hermle
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - David Schapiro
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Svjetlana Lovric
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Shirlee Shril
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Ankana Daga
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Ahmet Nayir
- Department of Pediatric Nephrology, Faculty of Medicine, University of Istanbul, Istanbul, Turkey
| | - Mohan Shenoy
- Department of Pediatric Nephrology, Royal Manchester Children's Hospital, Manchester, United Kingdom
| | - Yincent Tse
- Department of Pediatric Nephrology, Great North Children's Hospital, Newcastle Upon Tyne, United Kingdom
| | - Martin Bald
- Olga Children's Hospital, Clinic Stuttgart, Stuttgart, Germany
| | - Udo Helmchen
- Institute of Pathology, Kidney Registry, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Sevgi Mir
- Department of Pediatrics, Molecular Medicine Laboratory, Ege University, Izmir, Turkey
| | - Afig Berdeli
- Department of Pediatrics, Molecular Medicine Laboratory, Ege University, Izmir, Turkey
| | - Jameela A Kari
- Pediatric Nephrology Center of Excellence and Pediatric Department, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Sherif El Desoky
- Pediatric Nephrology Center of Excellence and Pediatric Department, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Neveen A Soliman
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Arvind Bagga
- Division of Pediatric Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | | | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA.,Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Seema Khurana
- Department of Biology and Biochemistry, University of Houston, Houston,Texas, USA.,Baylor College of Medicine, Houston, Texas, USA
| | - Jose C Martins
- NMR and Structure Analysis Group, Department of Organic and Macromolecular Chemistry, University of Gent, Gent, Belgium
| | - Friedhelm Hildebrandt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
11
|
ARF6 mediates nephrin tyrosine phosphorylation-induced podocyte cellular dynamics. PLoS One 2017; 12:e0184575. [PMID: 28880939 PMCID: PMC5589247 DOI: 10.1371/journal.pone.0184575] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/26/2017] [Indexed: 01/10/2023] Open
Abstract
ADP-ribosylation factor 6 (ARF6) is a small GTPase necessary for regulating cellular structure, motility, and vesicle trafficking. In several cellular systems, ARF6 was shown to regulate actin dynamics in coordination with Rac1, a Rho small GTPase. We examined the function of ARF6 in the kidney podocyte because Rac1 was implicated in kidney diseases involving this cell. We found that ARF6 expression was enriched in human podocytes and that it modulated podocyte cytoskeletal dynamics through a functional interaction with nephrin, an intercellular junction protein necessary for podocyte injury-induced signaling requiring activation by tyrosine phosphorylation of its cytoplasmic domain. ARF6 was necessary for nephrin activation-induced ruffling and focal adhesion turnover, possibly by altering Rac1 activity. In podocyte-specific Arf6 (ARF6_PodKO) knockout mice, ARF6 deficiency did not result in a spontaneous kidney developmental phenotype or proteinuria after aging. However, ARF6_PodKO mice exhibited distinct phenotypes in two in vivo glomerular injury models. In the protamine sulfate perfusion model, which induced acute podocyte effacement, ARF6_PodKO mice were protected from podocyte effacement. In the nephrotoxic serum nephritis model, which induced immune-complex mediated injury, ARF6_PodKO mice exhibited aggravated proteinuria. Together, these observations suggest that while ARF6 is necessary for nephrin tyrosine phosphorylation-induced cytoskeletal dynamics in cultured podocytes, ARF6 has pleotropic podocyte roles in vivo, where glomerular injury-specific mechanisms might activate distinct signaling pathways that dictate whether ARF6 activity is beneficial or deleterious for maintaining the integrity of the glomerular filtration barrier.
Collapse
|
12
|
Abstract
The glomerulus has 3 resident cells namely mesangial cells that produce the mesangial matrix, endothelial cells that line the glomerular capillaries, and podocytes that cover the outer surface of the glomerular basement membrane. Parietal epithelial cells (PrECs), which line the Bowman's capsule are not part of the glomerular tuft but may have an important role in the normal function of the glomerulus. A significant progress has been made in recent years regarding our understanding of the role and function of these cells in normal kidney and in kidneys with various types of glomerulopathy. In crescentic glomerulonephritis necrotizing injury of the glomerular tuft results in activation and leakage of fibrinogen which provides the trigger for excessive proliferation of PrECs giving rise to glomerular crescents. In cases of collapsing glomerulopathy, podocyte injury causes collapse of the glomerular capillaries and activation and proliferation of PrECs, which accumulate within the urinary space in the form of pseudocrescents. Many of the noninflammatory glomerular lesions such as focal segmental glomerulosclerosis and global glomerulosclerosis also result from podocyte injury which causes variable loss of podocytes. In these cases podocyte injury leads to activation of PrECs that extend on to the glomerular tuft where they cause segmental and/or global sclerosis by producing excess matrix, resulting in obliteration of the capillary lumina. In diabetic nephropathy, in addition to increased matrix production in the mesangium and glomerular basement membranes, increased loss of podocytes is an important determinant of long-term prognosis. Contrary to prior belief there is no convincing evidence for an active podocyte proliferation in any of the above mentioned glomerulopathies.
Collapse
|
13
|
Bondzie PA, Chen HA, Cao MZ, Tomolonis JA, He F, Pollak MR, Henderson JM. Non-muscle myosin-IIA is critical for podocyte f-actin organization, contractility, and attenuation of cell motility. Cytoskeleton (Hoboken) 2016; 73:377-95. [PMID: 27232264 DOI: 10.1002/cm.21313] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 05/20/2016] [Accepted: 05/25/2016] [Indexed: 12/12/2022]
Abstract
Several glomerular pathologies resulting from podocyte injury are linked to genetic variation involving the MYH9 gene, which encodes the heavy chain of non-muscle myosin-IIA (NM-IIA). However, the functional role of NM-IIA has not been studied extensively in podocytes. We hypothesized that NM-IIA is critical for maintenance of podocyte structure and mechanical function. To test this hypothesis, we studied murine podocytes in vitro subjected to blebbistatin inhibition of NM-II activity, or RNA interference-mediated, isoform-specific ablation of Myh9 gene and protein (NM-IIA) or its paralog Myh10 gene and protein (NM-IIB). Using quantitative immunofluorescence microscopy, traction force microscopy, and attachment and "wound healing" assays, we found that NM-IIA ablation altered podocyte actin cytoskeletal structure and focal adhesion distribution, decreased cell attachment and contractility, and increased cell motility. Blebbistatin treatment had similar effects. NM-IIB ablation produced cells that exhibited poor attachment, but cytoskeletal structural organization, contractility and motility were maintained. These findings indicate that NM-IIA is essential for maintenance of podocyte cytoskeletal structure and mechanical function in vitro, and NM-IIB does not replace it in this role when NM-IIA expression is altered. We conclude that critical podocyte functions may be affected by MYH9 mutations or disease-associated haplotypes. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Philip A Bondzie
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Hui A Chen
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Mei Zhen Cao
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Julie A Tomolonis
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Fangfang He
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Martin R Pollak
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Joel M Henderson
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| |
Collapse
|
14
|
Subramanian B, Sun H, Yan P, Charoonratana VT, Higgs HN, Wang F, Lai KMV, Valenzuela DM, Brown EJ, Schlöndorff JS, Pollak MR. Mice with mutant Inf2 show impaired podocyte and slit diaphragm integrity in response to protamine-induced kidney injury. Kidney Int 2016; 90:363-372. [PMID: 27350175 DOI: 10.1016/j.kint.2016.04.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/18/2016] [Accepted: 04/28/2016] [Indexed: 01/08/2023]
Abstract
Mutations in the INF2 (inverted formin 2) gene, encoding a diaphanous formin family protein that regulates actin cytoskeleton dynamics, cause human focal segmental glomerulosclerosis (FSGS). INF2 interacts directly with certain other mammalian diaphanous formin proteins (mDia) that function as RhoA effector molecules. FSGS-causing INF2 mutations impair these interactions and disrupt the ability of INF2 to regulate Rho/Dia-mediated actin dynamics in vitro. However, the precise mechanisms by which INF2 regulates and INF2 mutations impair glomerular structure and function remain unknown. Here, we characterize an Inf2 R218Q point-mutant (knockin) mouse to help answer these questions. Knockin mice have no significant renal pathology or proteinuria at baseline despite diminished INF2 protein levels. INF2 mutant podocytes do show impaired reversal of protamine sulfate-induced foot process effacement by heparin sulfate perfusion. This is associated with persistent podocyte cytoplasmic aggregation, nephrin phosphorylation, and nephrin and podocin mislocalization, as well as impaired recovery of mDia membrane localization. These changes were partially mimicked in podocyte outgrowth cultures, in which podocytes from knockin mice show altered cellular protrusions compared to those from wild-type mice. Thus, in mice, normal INF2 function is not required for glomerular development but normal INF2 is required for regulation of the actin-based behaviors necessary for response to and/or recovery from injury.
Collapse
Affiliation(s)
- Balajikarthick Subramanian
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Hua Sun
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; University of Children's Hospital, Iowa City, Iowa, USA
| | - Paul Yan
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Victoria T Charoonratana
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Henry N Higgs
- Department of Biochemistry, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Fang Wang
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Ka-Man V Lai
- Regeneron Pharmaceuticals, Tarrytown, New York, USA
| | | | - Elizabeth J Brown
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; Division of Nephrology, Department of Pediatrics, Children's Hospital, Boston, Massachusetts, USA; Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Johannes S Schlöndorff
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Martin R Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
| |
Collapse
|
15
|
Elvin J, Buvall L, Lindskog Jonsson A, Granqvist A, Lassén E, Bergwall L, Nyström J, Haraldsson B. Melanocortin 1 receptor agonist protects podocytes through catalase and RhoA activation. Am J Physiol Renal Physiol 2016; 310:F846-56. [PMID: 26887829 DOI: 10.1152/ajprenal.00231.2015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 02/15/2016] [Indexed: 11/22/2022] Open
Abstract
Drugs containing adrenocorticotropic hormone have been used as therapy for patients with nephrotic syndrome. We have previously shown that adrenocorticotropic hormone and a selective agonist for the melanocortin 1 receptor (MC1R) exert beneficial actions in experimental membranous nephropathy with reduced proteinuria, reduced oxidative stress, and improved glomerular morphology and function. Our hypothesis is that MC1R activation in podocytes elicits beneficial effects by promoting stress fibers and maintaining podocyte viability. To test the hypothesis, we cultured podocytes and used highly specific agonists for MC1R. Podocytes were subjected to the nephrotic-inducing agent puromycin aminonucleoside, and downstream effects of MC1R activation on podocyte survival, antioxidant defense, and cytoskeleton dynamics were studied. To increase the response and enhance intracellular signals, podocytes were transduced to overexpress MC1R. We showed that puromycin promotes MC1R expression in podocytes and that activation of MC1R promotes an increase of catalase activity and reduces oxidative stress, which results in the dephosphorylation of p190RhoGAP and formation of stress fibers through RhoA. In addition, MC1R agonists protect against apoptosis. Together, these mechanisms protect the podocyte against puromycin. Our findings strongly support the hypothesis that selective MC1R-activating agonists protect podocytes and may therefore be useful to treat patients with nephrotic syndromes commonly considered as podocytopathies.
Collapse
Affiliation(s)
- Johannes Elvin
- Department of Molecular and Clinical Medicine, Institute of Medicine, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden;
| | - Lisa Buvall
- Department of Physiology, Institute of Neuroscience and Physiology, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; and Department of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Annika Lindskog Jonsson
- Department of Molecular and Clinical Medicine, Institute of Medicine, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Anna Granqvist
- Department of Molecular and Clinical Medicine, Institute of Medicine, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Emelie Lassén
- Department of Molecular and Clinical Medicine, Institute of Medicine, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lovisa Bergwall
- Department of Physiology, Institute of Neuroscience and Physiology, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; and
| | - Jenny Nyström
- Department of Physiology, Institute of Neuroscience and Physiology, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; and
| | - Börje Haraldsson
- Department of Molecular and Clinical Medicine, Institute of Medicine, the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
16
|
Stankewich MC, Moeckel GW, Ji L, Ardito T, Morrow JS. Isoforms of Spectrin and Ankyrin Reflect the Functional Topography of the Mouse Kidney. PLoS One 2016; 11:e0142687. [PMID: 26727517 PMCID: PMC4703142 DOI: 10.1371/journal.pone.0142687] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 10/26/2015] [Indexed: 11/24/2022] Open
Abstract
The kidney displays specialized regions devoted to filtration, selective reabsorption, and electrolyte and metabolite trafficking. The polarized membrane pumps, channels, and transporters responsible for these functions have been exhaustively studied. Less examined are the contributions of spectrin and its adapter ankyrin to this exquisite functional topography, despite their established contributions in other tissues to cellular organization. We have examined in the rodent kidney the expression and distribution of all spectrins and ankyrins by qPCR, Western blotting, immunofluorescent and immuno electron microscopy. Four of the seven spectrins (αΙΙ, βΙ, βΙΙ, and βΙΙΙ) are expressed in the kidney, as are two of the three ankyrins (G and B). The levels and distribution of these proteins vary widely over the nephron. αΙΙ/βΙΙ is the most abundant spectrin, found in glomerular endothelial cells; on the basolateral membrane and cytoplasmic vesicles in proximal tubule cells and in the thick ascending loop of Henle; and less so in the distal nephron. βΙΙΙ spectrin largely replaces βΙΙ spectrin in podocytes, Bowman’s capsule, and throughout the distal tubule and collecting ducts. βΙ spectrin is only marginally expressed; its low abundance hinders a reliable determination of its distribution. Ankyrin G is the most abundant ankyrin, found in capillary endothelial cells and all tubular segments. Ankyrin B populates Bowman’s capsule, podocytes, the ascending thick loop of Henle, and the distal convoluted tubule. Comparison to the distribution of renal protein 4.1 isoforms and various membrane proteins indicates a complex relationship between the spectrin scaffold, its adapters, and various membrane proteins. While some proteins (e.g. ankyrin B, βΙΙΙ spectrin, and aquaporin 2) tend to share a similar distribution, there is no simple mapping of different spectrins or ankyrins to most membrane proteins. The implications of this data are discussed.
Collapse
Affiliation(s)
- Michael C. Stankewich
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States of America
- * E-mail:
| | - Gilbert W. Moeckel
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States of America
| | - Lan Ji
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States of America
| | - Thomas Ardito
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States of America
| | - Jon S. Morrow
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States of America
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, United States of America
| |
Collapse
|
17
|
Rodriguez PQ, Oddsson A, Ebarasi L, He B, Hultenby K, Wernerson A, Betsholtz C, Tryggvason K, Patrakka J. Knockdown of Tmem234 in zebrafish results in proteinuria. Am J Physiol Renal Physiol 2015; 309:F955-66. [PMID: 26377798 DOI: 10.1152/ajprenal.00525.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 09/10/2015] [Indexed: 12/15/2022] Open
Abstract
Podocytes are highly specialized epithelial cells located at the outer aspects of the glomerular capillary tuft and critical components of the kidney filtration barrier. To maintain their unique features, podocytes express a number of proteins that are only sparsely found elsewhere in the body. In this study, we have identified four (Tmem234, Znf185, Lrrc49, and Slfn5) new highly podocyte-enriched proteins. The proteins are strongly expressed by podocytes, while other parts of the kidney show only weak or no expression. Tmem234, Slfn5, and Lrrc49 are located in foot processes, whereas Znf185 is found in both foot and major processes. Expressional studies in developing kidneys show that these proteins are first expressed at the capillary stage glomerulus, the same stage when the formation of major and foot processes begins. We identified zebrafish orthologs for Tmem234 and Znf185 genes and knocked down their expression using morpholino technology. Studies in zebrafish larvae indicate that Tmem234 is essential for the organization and functional integrity of the pronephric glomerulus filtration barrier, as inactivation of Tmem234 expression results in foot process effacement and proteinuria. In summary, we have identified four novel highly podocyte-enriched proteins and show that one of them, Tmem234, is essential for the normal filtration barrier in the zebrafish pronephric glomerulus. Identification of new molecular components of the kidney filtration barrier opens up possibilities to study their role in glomerulus biology and diseases.
Collapse
Affiliation(s)
- Patricia Q Rodriguez
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Asmundur Oddsson
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Lwaki Ebarasi
- KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Bing He
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Hultenby
- Clinical Research Center, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Annika Wernerson
- Division of Renal Medicine, Department of Clinical Science, Intervention, and Technology, Stockholm, Sweden; and
| | - Christer Betsholtz
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; and
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School, Singapore
| | - Jaakko Patrakka
- KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden;
| |
Collapse
|
18
|
Three-dimensional architecture of podocytes revealed by block-face scanning electron microscopy. Sci Rep 2015; 5:8993. [PMID: 25759085 PMCID: PMC4355681 DOI: 10.1038/srep08993] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/12/2015] [Indexed: 12/31/2022] Open
Abstract
Block-face imaging is a scanning electron microscopic technique which enables easier acquisition of serial ultrastructural images directly from the surface of resin-embedded biological samples with a similar quality to transmission electron micrographs. In the present study, we analyzed the three-dimensional architecture of podocytes using serial block-face imaging. It was previously believed that podocytes are divided into three kinds of subcellular compartment: cell body, primary process, and foot process, which are simply aligned in this order. When the reconstructed podocytes were viewed from their basal side, the foot processes were branched from a ridge-like prominence, which was formed on the basal surface of the primary process and was similar to the usual foot processes in structure. Moreover, from the cell body, the foot processes were also emerged via the ridge-like prominence, as found in the primary process. The ridge-like prominence anchored the cell body and primary process to the glomerular basement membrane, and connected the foot processes to the cell body and primary process. In conclusion, serial block-face imaging is a powerful tool for clear understanding the three-dimensional architecture of podocytes through its ability to reveal novel structures which were difficult to determine by conventional transmission and scanning electron microscopes alone.
Collapse
|
19
|
Kanwar YS. Continuum of historical controversies regarding the structural-functional relationship of the glomerular ultrafiltration unit. Am J Physiol Renal Physiol 2014; 308:F420-4. [PMID: 25503736 DOI: 10.1152/ajprenal.00640.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Yashpal S Kanwar
- Departments of Pathology and Medicine, Northwestern University, Chicago, Illinois
| |
Collapse
|
20
|
Motonishi S, Nangaku M, Wada T, Ishimoto Y, Ohse T, Matsusaka T, Kubota N, Shimizu A, Kadowaki T, Tobe K, Inagi R. Sirtuin1 Maintains Actin Cytoskeleton by Deacetylation of Cortactin in Injured Podocytes. J Am Soc Nephrol 2014; 26:1939-59. [PMID: 25424328 DOI: 10.1681/asn.2014030289] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 10/03/2014] [Indexed: 12/30/2022] Open
Abstract
Recent studies have highlighted the renoprotective effect of sirtuin1 (SIRT1), a deacetylase that contributes to cellular regulation. However, the pathophysiologic role of SIRT1 in podocytes remains unclear. Here, we investigated the function of SIRT1 in podocytes. We first established podocyte-specific Sirt1 knockout (SIRT1(pod-/-)) mice. We then induced glomerular disease by nephrotoxic serum injection. The increase in urinary albumin excretion and BUN and the severity of glomerular injury were all significantly greater in SIRT1(pod-/-) mice than in wild-type mice. Western blot analysis and immunofluorescence showed a significant decrease in podocyte-specific proteins in SIRT1(pod-/-) mice, and electron microscopy showed marked exacerbation of podocyte injury, including actin cytoskeleton derangement in SIRT1(pod-/-) mice compared with wild-type mice. Protamine sulfate-induced podocyte injury was also exacerbated by podocyte-specific SIRT1 deficiency. In vitro, actin cytoskeleton derangement in H2O2-treated podocytes became prominent when the cells were pretreated with SIRT1 inhibitors. Conversely, this H2O2-induced derangement was ameliorated by SIRT1 activation. Furthermore, SIRT1 activation deacetylated the actin-binding and -polymerizing protein cortactin in the nucleus and facilitated deacetylated cortactin localization in the cytoplasm. Cortactin knockdown or inhibition of the nuclear export of cortactin induced actin cytoskeleton derangement and dissociation of cortactin from F-actin, suggesting the necessity of cytoplasmic cortactin for maintenance of the actin cytoskeleton. Taken together, these findings indicate that SIRT1 protects podocytes and prevents glomerular injury by deacetylating cortactin and thereby, maintaining actin cytoskeleton integrity.
Collapse
Affiliation(s)
| | | | | | - Yu Ishimoto
- Divisions of Nephrology and Endocrinology and
| | | | - Taiji Matsusaka
- Department of Internal Medicine, Tokai University School of Medicine, Kanagawa, Japan
| | - Naoto Kubota
- Department of Diabetes and Metabolic Diseases, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
| | - Akira Shimizu
- Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan; and
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
| | - Kazuyuki Tobe
- The First Department of Internal Medicine, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Reiko Inagi
- Divisions of Nephrology and Endocrinology and CKD Pathophysiology and
| |
Collapse
|
21
|
Sun H, Al-Romaih KI, MacRae CA, Pollak MR. Human Kidney Disease-causing INF2 Mutations Perturb Rho/Dia Signaling in the Glomerulus. EBioMedicine 2014; 1:107-15. [PMID: 26086034 PMCID: PMC4457406 DOI: 10.1016/j.ebiom.2014.11.009] [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: 09/18/2014] [Revised: 11/08/2014] [Accepted: 11/11/2014] [Indexed: 01/10/2023] Open
Abstract
Mutations in Inverted Formin 2 (INF2), a diaphanous formin family protein that regulates actin cytoskeleton dynamics, cause focal segmental glomerulosclerosis (FSGS) and Charcot-Marie-Tooth Disease (CMT) in humans. In addition to directly remodeling actin filaments in vitro, we have shown that INF2 regulates intracellular actin dynamics and actin dependent cellular behavior by opposing Rhoa/Dia signaling. As a step towards a better understanding of the human kidney disease, we wanted to explore the relevance of these findings to the in vivo situation. We used dose dependent knockdown of INF2 to first define an in vivo model and establish an overt glomerular phenotype in zebrafish. This simple assay was validated by rescue with wild type INF2 confirming the specificity of the findings. The edema, podocyte dysfunction, and an altered glomerular filtration barrier observed in the zebrafish pronephros correlate with mistrafficking of glomerular slit diaphragm proteins, defective slit-diaphragm signaling, and disinhibited diaphanous formin (mDia) activity. In contrast to wild-type human INF2, INF2 mutants associated with kidney disease fail to rescue the zINF2 morphant phenotype. Of particular interest, this INF2 knockdown phenotype is also rescued by loss of either RhoA or Dia2. This simple assay allows the demonstration that INF2 functions, at least in part, to modulate Dia-mediated Rho signaling, and that disease causing mutations specifically impair this regulatory function. These data support a model in which disease-associated diaphanous inhibitory domain (DID) mutants in INF2 interfere with its binding to and inhibition of Dia, leading to uncontrolled Rho/Dia signaling and perturbed actin dynamics. Methods to fine tune Rho signaling in the glomerulus may lead to new approaches to therapy in humans.
Collapse
Affiliation(s)
- Hua Sun
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, United States ; Harvard Medical School, Boston, MA 02215, United States ; Iowa University Children's Hospital, Iowa City, IA 52242, United States
| | - Khaldoun I Al-Romaih
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, United States ; Harvard Medical School, Boston, MA 02215, United States
| | - Calum A MacRae
- Harvard Medical School, Boston, MA 02215, United States ; Cardiology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, United States ; Broad Institute of Harvard and MIT, Cambridge, MA, United States
| | - Martin R Pollak
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, United States ; Harvard Medical School, Boston, MA 02215, United States ; Broad Institute of Harvard and MIT, Cambridge, MA, United States
| |
Collapse
|
22
|
Abstract
Glomerular disorders in infancy can include nephrotic and nephritic syndromes. Congenital nephrotic syndrome (CNS) is most commonly caused by single gene mutations in kidney proteins, but may also be due to congenital infections or passive transfer of maternal antibodies that target kidney proteins. Prenatal findings of increased maternal serum α-fetoprotein and enlarged placenta suggest CNS. Neonatal nephritis is rare; its causes may overlap with those of CNS and include primary glomerulonephritis, systemic disease, infections, and transplacental transfer of maternal antibodies. These syndromes in the neonate can cause significant morbidity and mortality, making urgent diagnosis and treatment necessary.
Collapse
Affiliation(s)
- Michelle N Rheault
- Division of Pediatric Nephrology, University of Minnesota Children's Hospital, 2450 Riverside Avenue, MB680, Minneapolis, MN 55454, USA.
| |
Collapse
|
23
|
Zennaro C, Mariotti M, Carraro M, Pasqualetti S, Corbelli A, Armelloni S, Li M, Ikehata M, Clai M, Artero M, Messa P, Boscutti G, Rastaldi MP. Podocyte developmental defects caused by adriamycin in zebrafish embryos and larvae: a novel model of glomerular damage. PLoS One 2014; 9:e98131. [PMID: 24845233 PMCID: PMC4028291 DOI: 10.1371/journal.pone.0098131] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 04/29/2014] [Indexed: 11/18/2022] Open
Abstract
The zebrafish pronephros is gaining popularity in the nephrology community, because embryos are easy to cultivate in multiwell plates, allowing large number of experiments to be conducted in an in vivo model. In a few days, glomeruli reach complete development, with a structure that is similar to that of the mammalian counterpart, showing a fenestrated endothelium and a basement membrane covered by the multiple ramifications of mature podocytes. As a further advantage, zebrafish embryos are permeable to low molecular compounds, and this explains their extensive use in drug efficacy and toxicity experiments. Here we show that low concentrations of adriamycin (i.e. 10 and 20 µM), when dissolved in the medium of zebrafish embryos at 9 hours post-fertilization and removed after 48 hours (57 hpf), alter the development of podocytes with subsequent functional impairment, demonstrated by onset of pericardial edema and reduction of expression of the podocyte proteins nephrin and wt1. Podocyte damage is morphologically confirmed by electron microscopy and functionally supported by increased clearance of microinjected 70 kDa fluorescent dextran. Importantly, besides pericardial edema and glomerular damage, which persist and worsen after adriamycin removal from the medium, larvae exposed to adriamycin 10 and 20 µM do not show any myocardiocyte alterations nor vascular changes. The only extra-renal effect is a transient delay of cartilage formation that rapidly recovers once adriamycin is removed. In summary, this low dose adriamycin model can be applied to analyze podocyte developmental defects, such as those observed in congenital nephrotic syndrome, and can be taken in consideration for pharmacological studies of severe early podocyte injury.
Collapse
Affiliation(s)
- Cristina Zennaro
- Department of Medical, Surgery and Health Sciences, Università degli Studi di Trieste, Trieste, Italy
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico & Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milano, Italy
- * E-mail:
| | - Massimo Mariotti
- Department of Biomedical, Surgical and Dental Sciences, University of Milano & IRCCS Orthopedic Institute, Milano, Italy
| | - Michele Carraro
- Department of Medical, Surgery and Health Sciences, Università degli Studi di Trieste, Trieste, Italy
| | | | - Alessandro Corbelli
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico & Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milano, Italy
- Department of Cardiovascular Research- Unit of Bio-imaging, Mario Negri Institute for Pharmacological Research, Milano, Italy
| | - Silvia Armelloni
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico & Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milano, Italy
| | - Min Li
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico & Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milano, Italy
| | - Masami Ikehata
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico & Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milano, Italy
| | - Milan Clai
- Azienda Ospedaliero-Universitaria Ospedali Riuniti di Trieste, Trieste, Italy
| | - Mary Artero
- Azienda Ospedaliero-Universitaria Ospedali Riuniti di Trieste, Trieste, Italy
| | - Piergiorgio Messa
- Division of Nephrology, Dialysis, and Renal Transplant, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - Giuliano Boscutti
- Azienda Ospedaliero-Universitaria Ospedali Riuniti di Trieste, Trieste, Italy
| | - Maria Pia Rastaldi
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico & Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milano, Italy
| |
Collapse
|
24
|
Li X, Zhang X, Li X, Wang X, Wang S, Ding J. Cyclosporine A protects podocytes via stabilization of cofilin-1 expression in the unphosphorylated state. Exp Biol Med (Maywood) 2014; 239:922-936. [PMID: 24737737 DOI: 10.1177/1535370214530365] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Podocyte foot process (FP) is dysregulated in nephrotic syndrome. The effacement of podocyte FPs typically arises following perturbations in the actin cytoskeleton. Recent data suggest that the effects of calcineurin (CaN) inhibitor cyclosporine A (CsA) are independent of its effects on T-cells, and CsA has been identified as stabilizing the actin cytoskeleton through stabilizing synaptopodin in podocytes, and thereby directly reducing proteinuria. Other studies showed that CsA could regulate cofilin-1 directly within tubular epithelial cells. However, whether synaptopodin is the only target of CsA or whether the antiproteinuric role of CsA is played by regulating cofilin-1 in podocytes has not been studied. In the present study, changes in the expression and distribution of nephrin, synaptopodin, cofilin-1 and phosphorylated cofilin-1 (pho-cofilin-1) were detected in both puromycin aminonucleoside (PAN) induced nephrotic rats treated with CsA and cultured podocytes exposed to PAN with/without CsA. Cofilin-1, synaptopodin mRNA was knocked down or combined by siRNA to investigate whether cofilin-1 was critical for the protective effect of CsA and whether the effect of CsA on cofilin-1 was independent of its effect on synaptopodin. We found that CsA reduced proteinuria and repaired FP effacement of PAN-induced nephropathy, restored expression of nephrin, synaptopodin, cofilin-1, pho-cofilin-1 both in vivo and in vitro. CsA also repaired actin cytoskeleton impaired by PAN in vitro. The protective effect of CsA was diminished when cofilin-1 was knocked down compared to negative control. Synaptopodin knocked down had no effect on cofilin-1. The protective effect of CsA decreased significantly when cofilin-1 and synaptopodin were simultaneously knocked down compared to only cofilin-1 knock down. In conclusion, the antiproteinuric effect of CsA is derived from the stabilization of the podocyte actin cytoskeleton by upregulating expression of cofilin-1, which was independent of its effect on synaptopodin.
Collapse
Affiliation(s)
- Xiaoyan Li
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Xiaoyan Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Xuejuan Li
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Xuejing Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Suxia Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Jie Ding
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| |
Collapse
|
25
|
Xie X, Colberg-Poley AM, Das JR, Li J, Zhang A, Tang P, Jerebtsova M, Gutkind JS, Ray PE. The basic domain of HIV-tat transactivating protein is essential for its targeting to lipid rafts and regulating fibroblast growth factor-2 signaling in podocytes isolated from children with HIV-1-associated nephropathy. J Am Soc Nephrol 2014; 25:1800-13. [PMID: 24578133 DOI: 10.1681/asn.2013070710] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Podocyte injury has a critical role in the pathogenesis of HIV-associated nephropathy (HIVAN). The HIV-1 transactivator of transcription (Tat), combined with fibroblast growth factor-2 (FGF-2), can induce the dedifferentiation and proliferation of cultured human podocytes. Cellular internalization of Tat requires interactions with heparan sulfate proteoglycans and cholesterol-enriched lipid rafts (LRs). However, the specific distribution of Tat in human podocytes and its ability to associate with LRs have not been documented. Here, we found that Tat is preferentially recruited to LRs in podocytes isolated from children with HIVAN. Furthermore, we identified arginines in the basic domain (RKKRRQRRR) of Tat as essential for (1) targeting Tat to LRs, (2) Tat-mediated increases in the expression of Rho-A and matrix metalloproteinase-9 in LRs, and (3) Tat-mediated enhancement of FGF-2 signaling in human podocytes and HIV-transgenic mouse kidneys and the exacerbation of renal lesions in these mice. Tat carrying alanine substitutions in the basic domain (AKKAAQAAA) remained localized in the cytosol and did not associate with LRs or enhance FGF-2 signaling in cultured podocytes. These results show the specific association of Tat with LRs in podocytes isolated from children with HIVAN, confirm Tat as a regulator of FGF-2 signaling in LRs, and identify the key domain of Tat responsible for promoting these effects and aggravating renal injury in HIV-transgenic mice. Moreover, these results provide a molecular framework for developing novel therapies to improve the clinical outcome of children with HIVAN.
Collapse
Affiliation(s)
| | - Anamaris M Colberg-Poley
- Center for Genetic Medicine Research and Department of Pediatrics, George Washington University, Washington, DC; and
| | | | | | | | - Pingtao Tang
- Center for Genetic Medicine Research and Department of Pediatrics, George Washington University, Washington, DC; and
| | - Marina Jerebtsova
- Center for Genetic Medicine Research and Department of Pediatrics, George Washington University, Washington, DC; and
| | - J Silvio Gutkind
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Patricio E Ray
- Center for Genetic Medicine Research and Department of Pediatrics, George Washington University, Washington, DC; and Division of Nephrology, Children's National Medical Center, Washington, DC;
| |
Collapse
|
26
|
Protection of human podocytes from shiga toxin 2-induced phosphorylation of mitogen-activated protein kinases and apoptosis by human serum amyloid P component. Infect Immun 2014; 82:1872-9. [PMID: 24566618 DOI: 10.1128/iai.01591-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hemolytic uremic syndrome (HUS) is mainly induced by Shiga toxin 2 (Stx2)-producing Escherichia coli. Proteinuria can occur in the early phase of the disease, and its persistence determines the renal prognosis. Stx2 may injure podocytes and induce proteinuria. Human serum amyloid P component (SAP), a member of the pentraxin family, has been shown to protect against Stx2-induced lethality in mice in vivo, presumably by specific binding to the toxin. We therefore tested the hypothesis that SAP can protect against Stx2-induced injury of human podocytes. To elucidate the mechanisms underlying podocyte injury in HUS-associated proteinuria, we assessed Stx2-induced activation of mitogen-activated protein kinases (MAPKs) and apoptosis in immortalized human podocytes and evaluated the impact of SAP on Stx2-induced damage. Human podocytes express Stx2-binding globotriaosylceramide 3. Stx2 applied to cultured podocytes was internalized and then activated p38α MAPK and c-Jun N-terminal kinase (JNK), important signaling steps in cell differentiation and apoptosis. Stx2 also activated caspase 3, resulting in an increased level of apoptosis. Coincubation of podocytes with SAP and Stx2 mitigated the effects of Stx2 and induced upregulation of antiapoptotic Bcl2. These data suggest that podocytes are a target of Stx2 and that SAP protects podocytes against Stx2-induced injury. SAP may therefore be a useful therapeutic option.
Collapse
|
27
|
Arif E, Rathore YS, Kumari B, Ashish F, Wong HN, Holzman LB, Nihalani D. Slit diaphragm protein Neph1 and its signaling: a novel therapeutic target for protection of podocytes against glomerular injury. J Biol Chem 2014; 289:9502-18. [PMID: 24554715 DOI: 10.1074/jbc.m113.505743] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Podocytes are specialized epithelial cells that are critical components of the glomerular filtration barrier, and their dysfunction leads to proteinuria and renal failure. Therefore, preserving podocyte function is therapeutically significant. In this study, we identified Neph1 signaling as a therapeutic target that upon inhibition prevented podocyte damage from a glomerular injury-inducing agent puromycin aminonucleoside (PAN). To specifically inhibit Neph1 signaling, we used a protein transduction approach, where the cytoplasmic domain of Neph1 (Neph1CD) tagged with a protein transduction domain trans-activator of transcription was transduced in cultured podocytes prior to treatment with PAN. The PAN-induced Neph1 phosphorylation was significantly reduced in Neph1CD-transduced cells; in addition, these cells were resistant to PAN-induced cytoskeletal damage. The biochemical analysis using subfractionation studies showed that unlike control cells Neph1 was retained in the lipid raft fractions in the transduced cells following treatment with PAN, indicating that transduction of Neph1CD in podocytes prevented PAN-induced mislocalization of Neph1. In accordance, the immunofluorescence analysis further suggested that Neph1CD-transduced cells had increased ability to retain endogenous Neph1 at the membrane in response to PAN-induced injury. Similar results were obtained when angiotensin was used as an injury-inducing agent. Consistent with these observations, maintaining high levels of Neph1 at the membrane using a podocyte cell line overexpressing chimeric Neph1 increased the ability of podocytes to resist PAN-induced injury and PAN-induced albumin leakage. Using a zebrafish in vivo PAN and adriamycin injury models, we further demonstrated the ability of transduced Neph1CD to preserve glomerular function. Collectively, these results support the conclusion that inhibiting Neph1 signaling is therapeutically significant in preventing podocyte damage from glomerular injury.
Collapse
Affiliation(s)
- Ehtesham Arif
- From the Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | | | | | | | | | | | | |
Collapse
|
28
|
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.
Collapse
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
| |
Collapse
|
29
|
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.
Collapse
|
30
|
Chang JM, Hwang DY, Chen SC, Kuo MC, Hung CC, Hwang SJ, Tsai JC, Chen HC. B7-1 expression regulates the hypoxia-driven cytoskeleton rearrangement in glomerular podocytes. Am J Physiol Renal Physiol 2012; 304:F127-36. [PMID: 23019228 DOI: 10.1152/ajprenal.00108.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Chronic hypoxia has been recognized as a common mechanism driving the progression of many glomerular diseases. Glomerular cells, although susceptible to hypoxic injuries, are less studied to unravel the hypoxia-related influences. In the present study, we showed that both lipopolysaccharide (LPS) and hypoxia induced B7-1 and hypoxia-inducible factor (HIF)-1α expression in podocytes. B7-1, an essential player in the regulation of podocyte stress fibers, interacted directly with the NH(2)-terminal oxygenation domain of HIF-1α protein and, therefore, might interfere with the HIF-related oxidative events. The suggestion was supported by the changes in the expression of inducible nitric oxide synthase and nitric oxide. The orderly arranged stress fibers in differentiated podocytes were disrupted by either LPS or hypoxic stimulation, and the disruption could be rescued if they were brought back to normal oxygen tension. Cell motility increased with the stimulation by LPS and hypoxia, most probably mediated by the induction of B7-1 and HIF-1α, respectively. We generated a B7-1 knockdown podocyte cell line using the lentiviral small interfering RNA system. The LPS- and hypoxia-induced stress fiber disruption was largely prevented in the B7-1 knockdown podocytes. The increased cell motility by LPS and hypoxia stimulations was also ameliorated in the B7-knockdown podocytes. In summary, we found that both B7-1 and HIF were upregulated by LPS and hypoxic stimulations in podocytes and they interacted with each other. Hypoxia disrupted the abundant stress fibers and increased cell motility. These hypoxia-induced changes were prevented in B7-knockdown podocytes, and they highlighted the importance of B7-1 expression in the hypoxia-related podocyte injuries.
Collapse
Affiliation(s)
- Jer-Ming Chang
- Department of Internal Medicine, Kaohsiung Municipal Hsiao-Kango Hospital, Kaohsiung, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Sistani L, Rodriguez PQ, Hultenby K, Uhlen M, Betsholtz C, Jalanko H, Tryggvason K, Wernerson A, Patrakka J. Neuronal proteins are novel components of podocyte major processes and their expression in glomerular crescents supports their role in crescent formation. Kidney Int 2012; 83:63-71. [PMID: 22913984 DOI: 10.1038/ki.2012.321] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The podocyte has a central role in the glomerular filtration barrier typified by a sophisticated morphology of highly organized primary (major) and secondary (foot) processes. The molecular makeup of foot processes is well characterized, but that of major processes is poorly known. Previously, we profiled the glomerular transcriptome through large-scale sequencing and microarray profiling. Unexpectedly, the survey found expression of three neuronal proteins (Huntingtin interacting protein 1 (Hip1), neurofascin (Nfasc), and olfactomedin-like 2a (Olfml2a)), all enriched in the glomerulus. These proteins were expressed exclusively by podocytes, wherein they localized to major processes as verified by RT-PCR, western blotting, immunofluorescence, and immunoelectron microscopy. During podocyte development, these proteins colocalized with vimentin, confirming their association with major processes. Using immunohistochemistry, we found coexpression of Hip1 and Olfml2a along with the recognized podocyte markers synaptopodin and Pdlim2 in glomerular crescents of human kidneys, indicating the presence of podocytes in these lesions. Thus, three neuronal proteins are highly expressed in podocyte major process. Using these new markers we found that podocytes contribute to the formation of glomerular crescents.
Collapse
Affiliation(s)
- Laleh Sistani
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Perisic L, Lal M, Hulkko J, Hultenby K, Önfelt B, Sun Y, Dunér F, Patrakka J, Betsholtz C, Uhlen M, Brismar H, Tryggvason K, Wernerson A, Pikkarainen T. Plekhh2, a novel podocyte protein downregulated in human focal segmental glomerulosclerosis, is involved in matrix adhesion and actin dynamics. Kidney Int 2012; 82:1071-83. [PMID: 22832517 DOI: 10.1038/ki.2012.252] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pleckstrin homology domain-containing, family H (with MyTH4 domain), member 2 (Plekhh2) is a 1491-residue intracellular protein highly enriched in renal glomerular podocytes for which no function has been ascribed. Analysis of renal biopsies from patients with focal segmental glomerulosclerosis revealed a significant reduction in total podocyte Plekhh2 expression compared to controls. Sequence analysis indicated a putative α-helical coiled-coil segment as the only recognizable domain within the N-terminal half of the polypeptide, while the C-terminal half contains two PH, a MyTH4, and a FERM domain. We identified a phosphatidylinositol-3-phosphate consensus-binding site in the PH1 domain required for Plekhh2 localization to peripheral regions of cell lamellipodia. The N-terminal half of Plekkh2 is not necessary for lamellipodial targeting but mediates self-association. Yeast two-hybrid screening showed that Plekhh2 directly interacts through its FERM domain with the focal adhesion protein Hic-5 and actin. Plekhh2 and Hic-5 coprecipitated and colocalized at the soles of podocyte foot processes in situ and Hic-5 partially relocated from focal adhesions to lamellipodia in Plekhh2-expressing podocytes. In addition, Plekhh2 stabilizes the cortical actin cytoskeleton by attenuating actin depolymerization. Our findings suggest a structural and functional role for Plekhh2 in the podocyte foot processes.
Collapse
Affiliation(s)
- Ljubica Perisic
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Is the antiproteinuric effect of cyclosporine a independent of its immunosuppressive function in T cells? Int J Nephrol 2012; 2012:809456. [PMID: 22778954 PMCID: PMC3384901 DOI: 10.1155/2012/809456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 04/20/2012] [Accepted: 05/03/2012] [Indexed: 12/21/2022] Open
Abstract
The antiproteinuric effect of cyclosporine A(CsA) has been believed to result from its immunosuppressive effect on the transcription factor NFAT in T cells. However, current evidences supporting this hypothesis are missing. A recent study showed that CsA has a direct antiproteinuric effect on podocytes, suggesting a novel non-immunosuppressive mechanism for CsA's antiproteinuric effect. Conditional NFATc1 activation in podoyctes per se is sufficient to induce proteinuria in mice, indicating that NFAT activation in podocytes is a critical pathogenic molecular event leading to podocyte injury and proteinuria. Meanwhile, evidence showed that TRPC6-mediated Ca(2+) influx stimulates NFAT-dependent TRPC6 expression. Altogether, these advances in podocyte research indicate that calcineurin-NFAT signal or calcineurin-synaptopodin axis has a direct proteinuric effect on podocytes which raises the possibility of developing specific antiproteinuric drugs that lack the unwanted effects of calcineurin or NFAT inhibition.
Collapse
|
34
|
Huang C, Bruggeman LA, Hydo LM, Miller RT. Shear stress induces cell apoptosis via a c-Src-phospholipase D-mTOR signaling pathway in cultured podocytes. Exp Cell Res 2012; 318:1075-85. [PMID: 22472346 DOI: 10.1016/j.yexcr.2012.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 03/15/2012] [Accepted: 03/18/2012] [Indexed: 02/06/2023]
Abstract
The glomerular capillary wall, composed of endothelial cells, the glomerular basement membrane and the podocytes, is continually subjected to hemodynamic force arising from tractional stress due to blood pressure and shear stress due to blood flow. Exposure of glomeruli to abnormal hemodynamic force such as hyperfiltration is associated with glomerular injury and progressive renal disease, and the conversion of mechanical stimuli to chemical signals in the regulation of the process is poorly understood in podocytes. By examining DNA fragmentation, apoptotic nuclear changes and cytochrome c release, we found that shear stress induced cell apoptosis in cultured podocytes. Meanwhile, podocytes exposed to shear stress also stimulated c-Src phosphorylation, phospholipase D (PLD) activation and mammalian target of rapamycin (mTOR) signaling. Using the antibodies against c-Src, PLD(1), and PLD(2) to perform reciprocal co-immunoprecipitations and in vitro PLD activity assay, our data indicated that c-Src interacted with and activated PLD(1) but not PLD(2). The inhibition of shear stress-induced c-Src phosphorylation by PP(2) (a specific inhibitor of c-Src kinase) resulted in reduced PLD activity. Phosphatidic acid, produced by shear stress-induced PLD activation, stimulated mTOR signaling, and caused podocyte hypertrophy and apoptosis.
Collapse
Affiliation(s)
- Chunfa Huang
- Louis Stokes Cleveland Veteran Affairs Medical Center, Case Western Reserve University, USA.
| | | | | | | |
Collapse
|
35
|
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.
Collapse
|
36
|
Fukasawa H, Obayashi H, Schmieder S, Lee J, Ghosh P, Farquhar MG. Phosphorylation of podocalyxin (Ser415) Prevents RhoA and ezrin activation and disrupts its interaction with the actin cytoskeleton. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:2254-65. [PMID: 21945805 DOI: 10.1016/j.ajpath.2011.07.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 07/12/2011] [Indexed: 01/01/2023]
Abstract
Podocalyxin (PC) is a polysialylated, anti-adhesin that is essential for maintaining foot process architecture and the integrity of the glomerular filtration barrier. We showed previously that PC is firmly attached to the actin cytoskeleton through ezrin, that in puromycin aminonucleoside (PAN)-mediated nephrosis the PC-ezrin-actin complex is disrupted, and that PC is uncoupled from actin. However, the precise mechanisms involved remained unknown. Here we show that detachment of PC from actin is regulated by phosphorylation of PC. PC is hyperphosphorylated at serines in PAN- and protamine sulfate (PS)-treated rat glomeruli. We determined that PC is a substrate of PKC and that the site of phosphorylation is Ser415, located within the juxtamembrane, ezrin-binding domain of the cytoplasmic tail of PC. Mutation of Ser415 to the phosphomimetic residues Glu (S415E) or Asp (S415D) interfered with direct binding of the PC cytoplasmic tail to ezrin in vitro. Moreover, stable expression of a phosphomimetic (S415E) PC mutant but not the WT or the phosphorylation-deficient (S415A) PC mutant, disrupted PC-ezrin-actin interaction, failed to activate RhoA, and the cytoskeletal linker, ezrin, remained inactive. Our data indicate that phosphorylation of PC at Ser415 prevents attachment of PC and ezrin to actin and highlights the strategic position of Ser415 and direct binding of PC to ezrin in regulating podocyte foot process architecture.
Collapse
Affiliation(s)
- Hirotaka Fukasawa
- Department of Medicine, Hamamatsu University School of Medicine, Japan
| | | | | | | | | | | |
Collapse
|
37
|
Kim JH, Mukherjee A, Madhavan SM, Konieczkowski M, Sedor JR. WT1-interacting protein (Wtip) regulates podocyte phenotype by cell-cell and cell-matrix contact reorganization. Am J Physiol Renal Physiol 2011; 302:F103-15. [PMID: 21900451 DOI: 10.1152/ajprenal.00419.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Podocytes respond to environmental cues by remodeling their slit diaphragms and cell-matrix adhesive junctions. Wt1-interacting protein (Wtip), an Ajuba family LIM domain scaffold protein expressed in the podocyte, coordinates cell adhesion changes and transcriptional responses to regulate podocyte phenotypic plasticity. We evaluated effects of Wtip on podocyte cell-cell and cell-matrix contact organization using gain-of- and loss-of-function methods. Endogenous Wtip targeted to focal adhesions in adherent but isolated podocytes and then shifted to adherens junctions after cells made stable, homotypic contacts. Podocytes with Wtip knockdown (shWtip) adhered but failed to spread normally. Noncontacted shWtip podocytes did not assemble actin stress fibers, and their focal adhesions failed to mature. As shWtip podocytes established cell-cell contacts, stable adherens junctions failed to form and F-actin structures were disordered. In shWtip cells, cadherin and β-catenin clustered in irregularly distributed spots that failed to laterally expand. Cell surface biotinylation showed diminished plasma membrane cadherin, β-catenin, and α-catenin in shWtip podocytes, although protein expression was similar in shWtip and control cells. Since normal actin dynamics are required for organization of adherens junctions and focal adhesions, we determined whether Wtip regulates F-actin assembly. Undifferentiated podocytes did not elaborate F-actin stress fibers, but when induced to overexpress WTIP, formed abundant stress fibers, a process blocked by the RhoA inhibitor C3 toxin and a RhoA kinase inhibitor. WTIP directly interacted with Rho guanine nucleotide exchange factor (GEF) 12 (Arhgef12), a RhoA-specific GEF enriched in the glomerulus. In conclusion, stable assembly of podocyte adherens junctions and cell-matrix contacts requires Wtip, a process that may be mediated by spatiotemporal regulation of RhoA activity through appropriate targeting of Arhgef12.
Collapse
Affiliation(s)
- Jane H Kim
- Departments of 1Physiology and Biophysics, MetroHealth System Campus, Case Western Reserve University, Cleveland, Ohio, USA
| | | | | | | | | |
Collapse
|
38
|
Abstract
The slit diaphragm and the apical and basal membrane domains of podocytes are connected to each other by an actin-based cytoskeleton critical to the maintenance of the glomerular filtration barrier. In an effort to discover novel regulatory proteins of the podocyte foot process, we identified and characterized pdlim2, a member of the actin-associated LIM protein subfamily of cytosolic proteins typified by an N-terminal PDZ domain and a C-terminal LIM domain. In the kidney, the pdlim2 protein is highly specific for the glomerulus and podocyte foot processes as shown by RT-PCR, western blotting, immunofluorescence, and immunoelectron microscopy. In cultured podocytes, pdlim2 was associated with stress fibers and cortical actin. Pdlim2 seems to regulate actin dynamics in podocytes since stress fibers were stabilized in its presence. Mechanistically, pdlim2 interacts with two actin-associated podocyte proteins, α-actinin-4 and angiomotin-like-1, as shown by immunoprecipitation and yeast two-hybrid analyses. By semi-quantitative immunoelectron microscopy, there was a reduced expression of pdlim2 in podocytes of patients with minimal change nephrotic syndrome and membranous nephropathy, whereas its expression was unchanged in patients with focal segmental glomerulosclerosis. Hence, pdlim2 is a novel actin-regulating protein of podocyte foot processes that may have a role in the pathogenesis of glomerular diseases.
Collapse
|
39
|
Bondeva T, Wojciech S, Wolf G. Advanced glycation end products inhibit adhesion ability of differentiated podocytes in a neuropilin-1-dependent manner. Am J Physiol Renal Physiol 2011; 301:F852-70. [PMID: 21734098 DOI: 10.1152/ajprenal.00575.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Podocyte injury can occur by a number of stimuli. Maintaining of an intact podocyte structure is essential for glomerular filtration; therefore, podocyte damage severely impairs renal function. Recently, we have reported that addition of glycated BSA [advanced glycation end products (AGE)-BSA] to differentiated murine podocytes inhibited neuropilin-1 (NRP1) expression and dramatically influenced podocyte migration ability (Bondeva T, Ruster C, Franke S, Hammerschmid E, Klagsbrun M, Cohen CD, Wolf G. Kidney Int 75: 605-616, 2009; Bondeva T, Wolf G. Am J Nephrol 30: 336-345, 2009). The present study analyzes the influence of AGEs and NRP1 on podocyte adhesion and cytoskeleton reorganization. We show that treatment with AGE-BSA significantly reduced podocyte adhesion to collagen IV, laminin, and fibronectin compared with Co-BSA (nonglycated BSA)-incubated cells, which was further augmented by transient inhibition of NRP1 expression using NRP1 short interference (si) RNA. On the other hand, forced overexpression of NRP1 markedly increased the adhesion ability of podocytes to the ECMs despite the AGE-BSA treatment. No changes were observed when podocyte adhesion to collagen I was assayed. These findings were also manifested with disorganization of podocyte actin stress fibers and decreased lamellipodia formation processes due to AGE-BSA treatment or NRP1 suppression. In addition, AGE-BSA or suppression of NRP1 both reduced the phosphorylation of focal adhesion kinase (FAK) and Erk1/2 in PMA-stimulated differentiated podocytes. Analysis of RhoA family GTPase activity demonstrated that treatment with AGE-BSA or NRP1 depletion inhibited as well the activation of the Rac-1 and Cdc42 but did not affect RhoA activity. All these effects were reversed by forced overexpression of full-length NRP1 cloned into the pcDNA3 vector in differentiated podocytes. Our study demonstrates that AGEs, in part via suppression of NRP1 expression, decreased podocyte adhesion and contribute to reduction of Rac-1 and Cdc42 GTPase activity. These effects may be further responsible for the podocytes damage and loss in diabetic nephropathy. Our findings suggest a role for NRP1 in regulating the podocyte actin cytoskeleton, and therefore reduction of NRP1 expression could be critical for podocyte function.
Collapse
Affiliation(s)
- Tzvetanka Bondeva
- Klinik für Innere Medizin III, Friedrich-Schiller- University, Jena, Germany
| | | | | |
Collapse
|
40
|
Zuo Y, Yang HC, Potthoff SA, Najafian B, Kon V, Ma LJ, Fogo AB. Protective effects of PPARγ agonist in acute nephrotic syndrome. Nephrol Dial Transplant 2011; 27:174-81. [PMID: 21565943 DOI: 10.1093/ndt/gfr240] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Peroxisome proliferator-activated receptor gamma (PPARγ) agonists have beneficial effects on renal structure and function in models of diabetes and chronic kidney diseases. However, the increased incidence of weight gain and edema potentially limits their usefulness. We studied an acute minimal-change disease-like nephrotic syndrome model to assess effects of PPARγ agonist on acute podocyte injury and effects on fluid homeostasis. METHODS Acute podocyte injury and nephrotic syndrome were induced by puromycin aminonucleoside (PAN) injection in rats. RESULTS PPARγ agonist, given at the time or after, but not before PAN, reduced proteinuria, restored synaptopodin, decreased desmin and trended to improve foot process effacement. There was no significant difference in glomerular filtration, effective circulating volume, blood pressure or fractional sodium excretion. PAN-injured podocytes had decreased PPARγ, less nephrin and α-actinin-4, more apoptosis and reduced phosphorylated Akt. In PAN-injured cultured podocytes, PPARγ agonist also reversed abnormalities only when given simultaneously or after injury. CONCLUSIONS These results show that PPARγ agonist has protective effects on podocytes in acute nephrotic syndrome without deleterious effects on fluid homeostasis. PPARγ agonist-induced decrease in proteinuria in acute nephrotic syndrome is dependent at least partially on regulation of peroxisome proliferator-response element-sensitive gene expression such as α-actinin-4 and nephrin and the restoration of podocyte structure.
Collapse
Affiliation(s)
- Yiqin Zuo
- Department of Pathology, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | | | | | | | | | | |
Collapse
|
41
|
Sekiguchi S, Suzuki A, Asano S, Nishiwaki-Yasuda K, Shibata M, Nagao S, Yamamoto N, Matsuyama M, Sato Y, Yan K, Yaoita E, Itoh M. Phosphate overload induces podocyte injury via type III Na-dependent phosphate transporter. Am J Physiol Renal Physiol 2011; 300:F848-56. [PMID: 21307129 DOI: 10.1152/ajprenal.00334.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Uptake of P(i) at the cellular membrane is essential for the maintenance of cell viability. However, phosphate overload is also stressful for cells and can result in cellular damage. In the present study, we investigated the effects of the transgenic overexpression of type III P(i) transporter Pit-1 to explore the role of extracellular P(i) in glomerular sclerosis during chronic renal disease. Pit-1 transgenic (TG) rats showed progressive proteinuria associated with hypoalbuminemia and dyslipidemia. Ultrastructural analysis of TG rat kidney by transmission electron microscopy showed a diffuse effacement of the foot processes of podocytes and a thickening of the glomerular basement membrane, which were progressively exhibited since 8 wk after birth. TG rats died at 32 wk of age due to cachexia. At this time, more thickening of the glomerular basement membrane and segmental sclerosis were observed in glomeruli of the TG rats. Immunohistochemical examination using anti-connexin 43 and anti-desmin antibodies suggested the progressive injury of podocytes in TG rats. TG rats showed higher P(i) uptake in podocytes than wild-type rats, especially under low P(i) concentration. When 8-wk-old wild-type and TG rats were fed a 0.6% normal phosphate (NP) or 1.2% phosphate (HP) diet for 12 wk, HP diet-treated TG rats showed more progressive proteinuria and higher serum creatinine levels than NP diet-treated TG rats. In conclusion, our findings suggest that overexpression of Pit-1 in rats induces phosphate-dependent podocyte injury and damage to the glomerular barrier, which result in the progression of glomerular sclerosis in the kidney.
Collapse
Affiliation(s)
- Sahoko Sekiguchi
- Div. of Endocrinology and Metabolism, Dept. of Internal Medicine, Fujita Health Univ., Kutsukake, Toyoake, Aichi 470-1192, Japan.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Direct dynamin-actin interactions regulate the actin cytoskeleton. EMBO J 2010; 29:3593-606. [PMID: 20935625 DOI: 10.1038/emboj.2010.249] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 09/10/2010] [Indexed: 01/13/2023] Open
Abstract
The large GTPase dynamin assembles into higher order structures that are thought to promote endocytosis. Dynamin also regulates the actin cytoskeleton through an unknown, GTPase-dependent mechanism. Here, we identify a highly conserved site in dynamin that binds directly to actin filaments and aligns them into bundles. Point mutations in the actin-binding domain cause aberrant membrane ruffling and defective actin stress fibre formation in cells. Short actin filaments promote dynamin assembly into higher order structures, which in turn efficiently release the actin-capping protein (CP) gelsolin from barbed actin ends in vitro, allowing for elongation of actin filaments. Together, our results support a model in which assembled dynamin, generated through interactions with short actin filaments, promotes actin polymerization via displacement of actin-CPs.
Collapse
|
43
|
Murea M, Freedman BI. Essential hypertension and risk of nephropathy: a reappraisal. Curr Opin Nephrol Hypertens 2010; 19:235-41. [PMID: 20051853 DOI: 10.1097/mnh.0b013e3283366344] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
PURPOSE OF REVIEW Treating mild-to-moderate essential hypertension in nondiabetic African Americans fails to halt nephropathy progression, whereas hypertension control slows nephropathy progression in European Americans. The pathogenesis of these disparate renal syndromes is reviewed. RECENT FINDINGS The nonmuscle myosin heavy chain 9 gene (MYH9) is associated with a spectrum of kidney diseases in African Americans, including idiopathic focal global glomerulosclerosis historically attributed to hypertension, idiopathic focal segmental glomerulosclerosis, and the collapsing variant of focal segmental glomerulosclerosis [HIV-associated nephropathy (HIVAN)]. Risk variants in MYH9 likely contribute to the failure of hypertension control to slow progressive kidney disease in nondiabetic African Americans. SUMMARY Early and intensive hypertension control fails to halt progression of 'hypertensive nephropathy' in African Americans. Genetic analyses in patients with essential hypertension and nephropathy attributed to hypertension, focal segmental glomerulosclerosis and HIVAN reveal that MYH9 gene polymorphisms are associated with a spectrum of kidney diseases in this ethnic group. Mild to moderate hypertension may cause nephropathy in European Americans with intrarenal vascular disease improved by the treatment of hypertension, hyperlipidemia and smoking cessation.
Collapse
Affiliation(s)
- Mariana Murea
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1053, USA
| | | |
Collapse
|
44
|
Hahn WH, Suh JS, Cho BS, Kim SD. The enabled homolog gene polymorphisms are associated with susceptibility and progression of childhood IgA nephropathy. Exp Mol Med 2010; 41:793-801. [PMID: 19641378 DOI: 10.3858/emm.2009.41.11.085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The enabled homolog gene (ENAH, hMena) is abundantly expressed in mesangial tissue, and might play an important role in inflammatory processes of IgA nephropathy (IgAN). The present study was conducted to investigate the association between single nucleotide polymorphisms (SNPs) of the ENAH and childhood IgAN. We analyzed 12 SNPs of ENAH in 176 patients with childhood IgAN and 397 healthy controls. In addition, IgAN patients were dichotomized and compared with respect to several clinical and pathological parameters. Genotyping data showed significant differences between IgAN patients and controls in the frequency of rs2039620, rs12034829, and rs3795443. On comparison of patients with proteinuria to those without proteinuria (< or = or >4 mg/m(2)/h), rs12043633 was significantly different between the two groups. With regard to maximum proteinuria (< or = or >4 mg/m(2)/h), rs3795443, rs4653643, rs6751, rs10799319, rs7555139, rs576861, and rs487591 showed significant allele frequency differences. For patients with and without gross hematuria, rs4653643, rs6751, rs10799319, rs7555139, rs576861, and rs487591 showed significant allele frequency differences. The rs3795443 was found to be associated with progression of pathological findings. Our results suggest that ENAH polymorphisms are associated with increased susceptibility, development of proteinuria and gross hematuria, and pathological progression of childhood IgAN.
Collapse
Affiliation(s)
- Won-Ho Hahn
- Department of Pediatrics, East West Kidney Diseases Research Institute, Kyung Hee University Hospital, Seoul 130-701, Korea
| | | | | | | |
Collapse
|
45
|
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.
Collapse
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.
| |
Collapse
|
46
|
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.
Collapse
Affiliation(s)
- Peter Mundel
- Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
| | | |
Collapse
|
47
|
Grillo-Hill BK, Wolff T. Dynamic cell shapes and contacts in the developing Drosophila retina are regulated by the Ig cell adhesion protein hibris. Dev Dyn 2009; 238:2223-34. [PMID: 19504462 DOI: 10.1002/dvdy.21981] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cell shapes and contacts are dynamically regulated during organogenesis to enable contacts with relevant neighboring cells at appropriate times. During Drosophila larval eye development, an apical contact is established between one pair of non-neuronal cones cells, precluding contact between the opposing pair. Concurrent with changes in cell shape, these contacts reverse in early pupal life. The reversal in cone cell contacts occurs in a posterior to anterior gradient across the eye, following the developmental gradient established in the larval eye imaginal disc. Hibris (Hbs), an Immunoglobulin cell adhesion molecule homologous to vertebrate Nephrin, is required for cone cell morphogenesis. In hbs null mutants, a majority of cone cells fail to both establish wild-type contacts and achieve mature cone cell shapes. hbs acts cell autonomously in the cone cells to drive these changes. The work presented here indicates hbs contributes to the remodeling of cell contacts and cell shapes throughout development.
Collapse
Affiliation(s)
- Bree K Grillo-Hill
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | |
Collapse
|
48
|
Patrakka J, Tryggvason K. New insights into the role of podocytes in proteinuria. Nat Rev Nephrol 2009; 5:463-8. [DOI: 10.1038/nrneph.2009.108] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
49
|
Triptolide protects podocytes from puromycin aminonucleoside induced injury in vivo and in vitro. Kidney Int 2008; 74:596-612. [DOI: 10.1038/ki.2008.203] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
50
|
Lee JH, Ha TS. Effects of puromycin aminonucleoside on the cytoskeletal changes of glomerular epithelial cells. KOREAN JOURNAL OF PEDIATRICS 2008. [DOI: 10.3345/kjp.2008.51.1.54] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Jun Ho Lee
- Department of Pediatrics, Pochon CHA University, College of Medicine, Korea
| | - Tae Sun Ha
- Department of Pediatrics, Chungbuk National University, College of Medicine, Korea
| |
Collapse
|