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Imeri F, Stepanovska Tanturovska B, Manaila R, Pavenstädt H, Pfeilschifter J, Huwiler A. Loss of S1P Lyase Expression in Human Podocytes Causes a Reduction in Nephrin Expression That Involves PKCδ Activation. Int J Mol Sci 2023; 24:ijms24043267. [PMID: 36834691 PMCID: PMC9965238 DOI: 10.3390/ijms24043267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023] Open
Abstract
Sphingosine 1-phosphate (S1P) lyase (SPL, Sgpl1) is an ER-associated enzyme that irreversibly degrades the bioactive lipid, S1P, and thereby regulates multiple cellular functions attributed to S1P. Biallelic mutations in the human Sglp1 gene lead to a severe form of a particular steroid-resistant nephrotic syndrome, suggesting that the SPL is critically involved in maintaining the glomerular ultrafiltration barrier, which is mainly built by glomerular podocytes. In this study, we have investigated the molecular effects of SPL knockdown (kd) in human podocytes to better understand the mechanism underlying nephrotic syndrome in patients. A stable SPL-kd cell line of human podocytes was generated by the lentiviral shRNA transduction method and was characterized for reduced SPL mRNA and protein levels and increased S1P levels. This cell line was further studied for changes in those podocyte-specific proteins that are known to regulate the ultrafiltration barrier. We show here that SPL-kd leads to the downregulation of the nephrin protein and mRNA expression, as well as the Wilms tumor suppressor gene 1 (WT1), which is a key transcription factor regulating nephrin expression. Mechanistically, SPL-kd resulted in increased total cellular protein kinase C (PKC) activity, while the stable downregulation of PKCδ revealed increased nephrin expression. Furthermore, the pro-inflammatory cytokine, interleukin 6 (IL-6), also reduced WT1 and nephrin expression. In addition, IL-6 caused increased PKCδ Thr505 phosphorylation, suggesting enzyme activation. Altogether, these data demonstrate that nephrin is a critical factor downregulated by the loss of SPL, which may directly cause podocyte foot process effacement as observed in mice and humans, leading to albuminuria, a hallmark of nephrotic syndrome. Furthermore, our in vitro data suggest that PKCδ could represent a new possible pharmacological target for the treatment of a nephrotic syndrome induced by SPL mutations.
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Affiliation(s)
- Faik Imeri
- Institute of Pharmacology, Inselspital, INO-F, University of Bern, CH-3010 Bern, Switzerland
| | | | - Roxana Manaila
- Institute of Pharmacology, Inselspital, INO-F, University of Bern, CH-3010 Bern, Switzerland
| | - Hermann Pavenstädt
- Medizinische Klinik D, University Hospital Münster, D-48149 Münster, Germany
| | - Josef Pfeilschifter
- Pharmazentrum Frankfurt/ZAFES, University Hospital, Goethe University Frankfurt am Main, Theodor-Stern Kai 7, D-60590 Frankfurt am Main, Germany
| | - Andrea Huwiler
- Institute of Pharmacology, Inselspital, INO-F, University of Bern, CH-3010 Bern, Switzerland
- Correspondence: ; Tel.: +41-31-632-32-14
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Stec DE, Tiribelli C, Badmus OO, Hinds TD. Novel Function for Bilirubin as a Metabolic Signaling Molecule: Implications for Kidney Diseases. KIDNEY360 2022; 3:945-953. [PMID: 36128497 PMCID: PMC9438427 DOI: 10.34067/kid.0000062022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 03/24/2022] [Indexed: 01/30/2023]
Abstract
Bilirubin is the end product of the catabolism of heme via the heme oxygenase pathway. Heme oxygenase generates carbon monoxide (CO) and biliverdin from the breakdown of heme, and biliverdin is rapidly reduced to bilirubin by the enzyme biliverdin reductase (BVR). Bilirubin has long been thought of as a toxic product that is only relevant to health when blood levels are severely elevated, such as in clinical jaundice. The physiologic functions of bilirubin correlate with the growing body of evidence demonstrating the protective effects of serum bilirubin against cardiovascular and metabolic diseases. Although the correlative evidence suggests a protective effect of serum bilirubin against many diseases, the mechanism by which bilirubin offers protection against cardiovascular and metabolic diseases remains unanswered. We recently discovered a novel function for bilirubin as a signaling molecule capable of activating the peroxisome proliferator-activated receptor α (PPARα) transcription factor. This review summarizes the new finding of bilirubin as a signaling molecule and proposes several mechanisms by which this novel action of bilirubin may protect against cardiovascular and kidney diseases.
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Affiliation(s)
- David E. Stec
- Department of Physiology and Biophysics, Cardiorenal, and Metabolic Diseases Research Center, University of Mississippi Medical Center, Jackson, Mississippi
| | | | - Olufunto O. Badmus
- Department of Physiology and Biophysics, Cardiorenal, and Metabolic Diseases Research Center, University of Mississippi Medical Center, Jackson, Mississippi
| | - Terry D. Hinds
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky,Barnstable Brown Diabetes Center, University of Kentucky, Lexington, Kentucky,Markey Cancer Center, University of Kentucky, Lexington, Kentucky
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Wang L, Tang Y, Buckley AF, Spurney RF. Blockade of the natriuretic peptide clearance receptor attenuates proteinuria in a mouse model of focal segmental glomerulosclerosis. Physiol Rep 2021; 9:e15095. [PMID: 34755480 PMCID: PMC8578888 DOI: 10.14814/phy2.15095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 12/31/2022] Open
Abstract
Glomerular podocytes play a key role in proteinuric diseases. Accumulating evidence suggests that cGMP signaling has podocyte protective effects. The major source of cGMP generation in podocytes is natriuretic peptides. The natriuretic peptide clearance receptor (NPRC) binds and degrades natriuretic peptides. As a result, NPRC inhibits natriuretic peptide-induced cGMP generation. To enhance cGMP generation in podocytes, we blocked natriuretic peptide clearance using the specific NPRC ligand ANP(4-23). We then studied the effects of NPRC blockade in both cultured podocytes and in a mouse transgenic (TG) model of focal segmental glomerulosclerosis (FSGS) created in our laboratory. In this model, a single dose of the podocyte toxin puromycin aminonucleoside (PAN) causes robust albuminuria in TG mice, but only mild disease in non-TG animals. We found that natriuretic peptides protected cultured podocytes from PAN-induced apoptosis, and that ANP(4-23) enhanced natriuretic peptide-induced cGMP generation in vivo. PAN-induced heavy proteinuria in vehicle-treated TG mice, and this increase in albuminuria was reduced by treatment with ANP(4-23). Treatment with ANP(4-23) also reduced the number of mice with glomerular injury and enhanced urinary cGMP excretion, but these differences were not statistically significant. Systolic BP was similar in vehicle and ANP(4-23)-treated mice. These data suggest that: 1. Pharmacologic blockade of NPRC may be useful for treating glomerular diseases such as FSGS, and 2. Treatment outcomes might be improved by optimizing NPRC blockade to inhibit natriuretic peptide clearance more effectively.
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Affiliation(s)
- Liming Wang
- Division of NephrologyDepartment of MedicineDuke University and Durham VA Medical CentersDurhamNorth CarolinaUSA
| | - Yuping Tang
- Division of NephrologyDepartment of MedicineDuke University and Durham VA Medical CentersDurhamNorth CarolinaUSA
| | - Anne F. Buckley
- Department of PathologyDuke University Medical CenterDurhamNorth CarolinaUSA
| | - Robert F. Spurney
- Division of NephrologyDepartment of MedicineDuke University and Durham VA Medical CentersDurhamNorth CarolinaUSA
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Imeri F, Stepanovska Tanturovska B, Schwalm S, Saha S, Zeng-Brouwers J, Pavenstädt H, Pfeilschifter J, Schaefer L, Huwiler A. Loss of sphingosine kinase 2 enhances Wilm's tumor suppressor gene 1 and nephrin expression in podocytes and protects from streptozotocin-induced podocytopathy and albuminuria in mice. Matrix Biol 2021; 98:32-48. [PMID: 34015468 DOI: 10.1016/j.matbio.2021.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/10/2021] [Accepted: 05/10/2021] [Indexed: 12/11/2022]
Abstract
The sphingosine 1-phosphate (S1P) is a bioactive sphingolipid that is now appreciated as key regulatory factor for various cellular functions in the kidney, including matrix remodeling. It is generated by two sphingosine kinases (Sphk), Sphk1 and Sphk2, which are ubiquitously expressed, but have distinct enzymatic activities and subcellular localizations. In this study, we have investigated the role of Sphk2 in podocyte function and its contribution to diabetic nephropathy. We show that streptozotocin (STZ)-induced nephropathy and albuminuria in mice is prevented by genetic depletion of Sphk2. This protection correlated with an increased protein expression of the transcription factor Wilm's tumor suppressor gene 1 (WT1) and its target gene nephrin, and a reduced macrophage infiltration in immunohistochemical renal sections of STZ-treated Sphk2-/- mice compared to STZ-treated wildtype mice. To investigate changes on the cellular level, we used an immortalized human podocyte cell line and generated a stable knockdown of Sphk2 (Sphk2-kd) by a lentiviral transduction method. These Sphk2-kd cells accumulated sphingosine as a consequence of the knockdown, and showed enhanced nephrin and WT1 mRNA and protein expressions similar to the finding in Sphk2 knockout mice. Treatment of wildtype podocytes with the highly selective Sphk2 inhibitor SLM6031434 caused a similar upregulation of nephrin and WT1 expression. Furthermore, exposing cells to the profibrotic mediator transforming growth factor β (TGFβ) resulted on the one side in reduced nephrin and WT1 expression, but on the other side, in upregulation of various profibrotic marker proteins, including connective tissue growth factor (CTGF), fibronectin (FN) and plasminogen activator inhibitor (PAI) 1. All these effects were reverted by Sphk2-kd and SLM6031434. Mechanistically, the protection by Sphk2-kd may depend on accumulated sphingosine and inhibited PKC activity, since treatment of cells with exogenous sphingosine not only reduced the phosphorylation pattern of PKC substrates, but also increased WT1 protein expression. Moreover, the selective stable knockdown of PKCδ increased WT1 expression, suggesting the involvement of this PKC isoenzyme in WT1 regulation. The glucocorticoid dexamethasone, which is a treatment option in many glomerular diseases and is known to mediate a nephroprotection, not only downregulated Sphk2 and enhanced cellular sphingosine, but also enhanced WT1 and nephrin expressions, thus, suggesting that parts of the nephroprotective effect of dexamethasone is mediated by Sphk2 downregulation. Altogether, our data demonstrated that loss of Sphk2 is protective in diabetes-induced podocytopathy and can prevent proteinuria, which is a hallmark of many glomerular diseases. Thus, Sphk2 could serve as a new attractive pharmacological target to treat proteinuric kidney diseases.
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Affiliation(s)
- Faik Imeri
- Institute of Pharmacology, University of Bern, Inselspital, INO-F, Bern CH-3010, Switzerland
| | | | - Stephanie Schwalm
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Sarbari Saha
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Jinyang Zeng-Brouwers
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Herrmann Pavenstädt
- Medizinische Klinik D, University Hospital Münster, Münster D-48149, Germany
| | - Josef Pfeilschifter
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Liliana Schaefer
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany.
| | - Andrea Huwiler
- Institute of Pharmacology, University of Bern, Inselspital, INO-F, Bern CH-3010, Switzerland.
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Niazi M, Shirpoor A, Taghizadeh Afshari A, Naderi R, Bagheri M, Pourjabali M, Rasmi Y. Cyclosporine A induces kidney dysfunction by the alteration of molecular mediators involved in slit diaphragm regulation and matrix metalloproteins: the mitigating effect of curcumin. Expert Opin Drug Metab Toxicol 2020; 16:1223-1231. [PMID: 32905741 DOI: 10.1080/17425255.2020.1822323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
BACKGROUND This research aimed at investigating the cyclosporine A intake impact with/without curcumin on podocyte protein gene expressions and matrix metalloproteins (MMPs) changes in rat kidney. METHODS Thirty-two Wistar male rats were assigned to the control, sham, cyclosporine A, and cyclosporine A with curcumin groups. RESULTS A significant increase was observed in CD2AP, ACTN4, podocin and also MMP9 and 2, cystatin C levels in the cyclosporine A group following treatment for four weeks, whereas a decrease was found in nephrin gene expression than the control group. In addition, a significant reduction was observed in the cyclosporine A group in glomerular filtration rate (GFR), urine creatinine, and increased plasma creatinine levels than the control group. Using curcumin plus cyclosporine A ameliorated gene expression alterations and increased the reduced amount of GFR, urine urea, and creatinine while reducing the increased plasma cystatine C, urea, and creatinine levels compared with the cyclosporine A group. CONCLUSION Accordingly, cyclosporine A-induced kidney abnormalities are possibly associated with changes in podocyte intra- and extra-cellular protein gene expression that influence the quality of filtrated fluid via altering the foot process shape and slit diaphragm size. Finally, such impacts are reduced via curcumin as an antioxidant and anti-inflammatory compound.
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Affiliation(s)
- Mona Niazi
- Nephrology and Kidney Transplant Research Center, Urmia University of Medical Sciences , Urmia, Iran.,Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences , Urmia, Iran
| | - Alireza Shirpoor
- Nephrology and Kidney Transplant Research Center, Urmia University of Medical Sciences , Urmia, Iran.,Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences , Urmia, Iran
| | - Ali Taghizadeh Afshari
- Nephrology and Kidney Transplant Research Center, Urmia University of Medical Sciences , Urmia, Iran
| | - Roya Naderi
- Nephrology and Kidney Transplant Research Center, Urmia University of Medical Sciences , Urmia, Iran
| | - Morteza Bagheri
- Nephrology and Kidney Transplant Research Center, Urmia University of Medical Sciences , Urmia, Iran
| | - Masoumeh Pourjabali
- Nephrology and Kidney Transplant Research Center, Urmia University of Medical Sciences , Urmia, Iran
| | - Yousef Rasmi
- Department of Biochemistry, Faculty of Medicine, Urmia University of Medical Sciences , Urmia, Iran
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Dai ZW, Cai KD, Xu LC, Wang LL. Perilipin2 inhibits diabetic nephropathy-induced podocyte apoptosis by activating the PPARγ signaling pathway. Mol Cell Probes 2020; 53:101584. [PMID: 32387304 DOI: 10.1016/j.mcp.2020.101584] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/09/2020] [Accepted: 04/23/2020] [Indexed: 01/20/2023]
Abstract
Podocyte apoptosis plays a pivotal role in the pathogenesis of diabetic nephropathy (DN). The main purpose of this study was to investigate the effects of perilipin2 on high glucose (HG)-induced podocyte apoptosis and associated mechanisms. Differentially expressed genes (DEGs) in BTBR ob/ob mice vs. nondiabetic mice kidneys were obtained from GSE106841 dataset and picked out using the 'limma' package. The protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) and was visualized by Cytoscape. Perilipin2 was a hub gene using the cytoHubba plug-in from Cytoscape. Gene ontology (GO) analysis revealed that the 126 overlapping DEGs were mainly enriched in 'oxidation reduction' [biological process, (BP)], metal ion binding' [molecular function, (MF)] and 'extracellular region' [cellular component, (CC)]. KEGG pathway analysis revealed that perilipin2 was mainly involved in 'PPAR signaling pathway'. DN inhibited perilipin2 expression and PPARγ expression, as by both in vitro and in vivo studies. In vitro experiments demonstrated that perilipin2 inhibition could not only reduced PPARγ expression in podocytes, it could also promote the apoptosis, and inhibit the viability in HG treated podocytes using western blot, CCK8 and flow cytometry assays. Perilipin2 overexpression reversed the effects of HG on inhibiting podocalyxin, nephrin, precursor (pro)-caspase-3/-9 and PPARγ protein expression and increasing cleaved caspase-3/-9 protein expression. Furthermore, the functions of perilipin2 overexpression reversing HG-induced podocyte apoptosis were inhibited by PPARγ inhibitor. In conclusion, the functions of DN-induced podocyte apoptosis were inhibited by activation of the PPARγ signaling pathway caused by perilipin2 overexpression.
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Affiliation(s)
- Zhi-Wei Dai
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China; Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China.
| | - Ke-Dan Cai
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China; Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China
| | - Ling-Cang Xu
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China; Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China
| | - Lai-Liang Wang
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China; Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, China
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Naidenow J, Hrgovic I, Doll M, Hailemariam-Jahn T, Lang V, Kleemann J, Kippenberger S, Kaufmann R, Zöller N, Meissner M. Peroxisome proliferator-activated receptor (PPAR) α and δ activators induce ICAM-1 expression in quiescent non stimulated endothelial cells. JOURNAL OF INFLAMMATION-LONDON 2016; 13:27. [PMID: 27547125 PMCID: PMC4992265 DOI: 10.1186/s12950-016-0135-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 08/10/2016] [Indexed: 01/29/2023]
Abstract
Background Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that are implicated in the regulation of lipid and glucose homeostasis. PPAR agonists have been shown to control inflammatory processes, in part by inhibiting the expression of distinct proinflammatory genes such as vascular cell adhesion molecule-1 (VCAM-1), IL-8, and intercellular adhesion molecule-1 (ICAM-1). ICAM-1 is an important endothelial membrane receptor that facilitates the transmigration of leukocytes across the endothelium. To date, the influence of PPARα and δ activators on the expression of ICAM-1 in non-induced, quiescent endothelial cells has been unclear. Therefore, we examined the effects of various PPARα and δ agonists on the expression of ICAM-1 in non-stimulated primary human endothelial cells. Results We found that PPARα and PPARδ agonists significantly induced ICAM-1 surface, intracellular protein, and mRNA expression in a time and concentration-dependent manner. The PPARδ induced ICAM-1 expression could be paralleled with a significantly increased T-cell adherence to the endothelial cells whereas PPARα failed to do so. Transcriptional activity studies using an ICAM-1 reporter gene constructs revealed that PPARδ, but not PPARα agonists induced gene expression by stimulating ICAM-1 promoter activity via an Sp1 transcription factor binding site and inhibit the binding of the transcription factors Sp1 and Sp3. Furthermore, we performed mRNA stability assays and found that PPARα and PPARδ agonists increased ICAM-1 mRNA stability. Conclusion Therefore, our data provide the first evidence that PPARα and PPARδ agonists induce ICAM-1 expression in non-stimulated endothelial cells via transcriptional and posttranscriptional mechanisms.
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Affiliation(s)
- Julia Naidenow
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Igor Hrgovic
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Monika Doll
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Tsige Hailemariam-Jahn
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Victoria Lang
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Johannes Kleemann
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Stefan Kippenberger
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Roland Kaufmann
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Nadja Zöller
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - Markus Meissner
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
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Abstract
The kidney is arguably the most important target of microvascular damage in diabetes. A substantial proportion of individuals with diabetes will develop kidney disease owing to their disease and/or other co-morbidity, including hypertension and ageing-related nephron loss. The presence and severity of chronic kidney disease (CKD) identify individuals who are at increased risk of adverse health outcomes and premature mortality. Consequently, preventing and managing CKD in patients with diabetes is now a key aim of their overall management. Intensive management of patients with diabetes includes controlling blood glucose levels and blood pressure as well as blockade of the renin-angiotensin-aldosterone system; these approaches will reduce the incidence of diabetic kidney disease and slow its progression. Indeed, the major decline in the incidence of diabetic kidney disease (DKD) over the past 30 years and improved patient prognosis are largely attributable to improved diabetes care. However, there remains an unmet need for innovative treatment strategies to prevent, arrest, treat and reverse DKD. In this Primer, we summarize what is now known about the molecular pathogenesis of CKD in patients with diabetes and the key pathways and targets implicated in its progression. In addition, we discuss the current evidence for the prevention and management of DKD as well as the many controversies. Finally, we explore the opportunities to develop new interventions through urgently needed investment in dedicated and focused research. For an illustrated summary of this Primer, visit: http://go.nature.com/NKHDzg.
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Barutta F, Grimaldi S, Franco I, Bellini S, Gambino R, Pinach S, Corbelli A, Bruno G, Rastaldi MP, Aveta T, Hirsch E, Di Marzo V, Gruden G. Deficiency of cannabinoid receptor of type 2 worsens renal functional and structural abnormalities in streptozotocin-induced diabetic mice. Kidney Int 2014; 86:979-90. [DOI: 10.1038/ki.2014.165] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 01/09/2023]
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Cizkova K, Rajdova A, Ehrmann J. Spatio-temporal expression of peroxisome proliferator-activated receptor α during human prenatal development. Basic Clin Pharmacol Toxicol 2014; 116:361-6. [PMID: 25225039 DOI: 10.1111/bcpt.12326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/15/2014] [Indexed: 11/30/2022]
Abstract
Peroxisome proliferator-activated receptor α (PPARα) is a ligand-dependent transcription factor which is activated by various endogenous as well as exogenous compounds. It is involved in the regulation of a variety of biological processes, such as nutrient metabolism, energy homoeostasis, immunological response and xenobiotic metabolism. Little is known about its expression during human prenatal development. We examined the spatio-temporal expression pattern of PPARα in human embryonic/foetal intestines, liver and kidney from the 5th to 20th week of prenatal life by indirect two-step immunohistochemistry. PPARα expression can already be detected in the early stages of prenatal development; as early as the 7th week of intrauterine development (IUD) in the intestines, 5th week of IUD in the liver and 6th week of IUD in the kidney. We found age-dependent changes in the PPARα expression pattern in the intestines and kidney. These events occur approximately at the commencement of function of these organs. In the intestines, we detected an obvious change of the PPARα expression pattern along the crypt-villous axis in the 11th week of IUD. In the kidney, the most apparent change was increased expression of PPARα in glomeruli in the 12th week of IUD. Moreover, in the liver, we detected a strong positivity in part of the developing blood elements. Information about the spatio-temporal expression pattern of PPARα could be the first step in evaluating the potential harmful impact of a wide range of environmental or pharmaceutical compounds which serve as PPARα ligands on the developing human organism.
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Affiliation(s)
- Katerina Cizkova
- Department of Histology and Embryology, Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic
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Functions of the podocyte proteins nephrin and Neph3 and the transcriptional regulation of their genes. Clin Sci (Lond) 2013; 126:315-28. [DOI: 10.1042/cs20130258] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nephrin and Neph-family proteins [Neph1–3 (nephrin-like 1–3)] belong to the immunoglobulin superfamily of cell-adhesion receptors and are expressed in the glomerular podocytes. Both nephrin and Neph-family members function in cell adhesion and signalling, and thus regulate the structure and function of podocytes and maintain normal glomerular ultrafiltration. The expression of nephrin and Neph3 is altered in human proteinuric diseases emphasizing the importance of studying the transcriptional regulation of the nephrin and Neph3 genes NPHS1 (nephrosis 1, congenital, Finnish type) and KIRREL2 (kin of IRRE-like 2) respectively. The nephrin and Neph3 genes form a bidirectional gene pair, and they share transcriptional regulatory mechanisms. In the present review, we summarize the current knowledge of the functions of nephrin and Neph-family proteins and transcription factors and agents that control nephrin and Neph3 gene expression.
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Cheng X, Zhao X, Khurana S, Bruggeman LA, Kao HY. Microarray analyses of glucocorticoid and vitamin D3 target genes in differentiating cultured human podocytes. PLoS One 2013; 8:e60213. [PMID: 23593176 PMCID: PMC3617172 DOI: 10.1371/journal.pone.0060213] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 02/22/2013] [Indexed: 12/26/2022] Open
Abstract
Glomerular podocytes are highly differentiated epithelial cells that are key components of the kidney filtration units. Podocyte damage or loss is the hallmark of nephritic diseases characterized by severe proteinuria. Recent studies implicate that hormones including glucocorticoids (ligand for glucocorticoid receptor) and vitamin D3 (ligand for vitamin D receptor) protect or promote repair of podocytes from injury. In order to elucidate the mechanisms underlying hormone-mediated podocyte-protecting activity from injury, we carried out microarray gene expression studies to identify the target genes and corresponding pathways in response to these hormones during podocyte differentiation. We used immortalized human cultured podocytes (HPCs) as a model system and carried out in vitro differentiation assays followed by dexamethasone (Dex) or vitamin D3 (VD3) treatment. Upon the induction of differentiation, multiple functional categories including cell cycle, organelle dynamics, mitochondrion, apoptosis and cytoskeleton organization were among the most significantly affected. Interestingly, while Dex and VD3 are capable of protecting podocytes from injury, they only share limited target genes and affected pathways. Compared to VD3 treatment, Dex had a broader and greater impact on gene expression profiles. In-depth analyses of Dex altered genes indicate that Dex crosstalks with a broad spectrum of signaling pathways, of which inflammatory responses, cell migration, angiogenesis, NF-κB and TGFβ pathways are predominantly altered. Together, our study provides new information and identifies several new avenues for future investigation of hormone signaling in podocytes.
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Affiliation(s)
- Xiwen Cheng
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU) and the Comprehensive Cancer Center of CWRU, Cleveland, Ohio, United States of America
| | - Xuan Zhao
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU) and the Comprehensive Cancer Center of CWRU, Cleveland, Ohio, United States of America
| | - Simran Khurana
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU) and the Comprehensive Cancer Center of CWRU, Cleveland, Ohio, United States of America
| | - Leslie A. Bruggeman
- Rammelkamp Center for Education and Research and Department of Medicine, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Hung-Ying Kao
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU) and the Comprehensive Cancer Center of CWRU, Cleveland, Ohio, United States of America
- * E-mail:
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Thomas MC. Emerging drugs for managing kidney disease in patients with diabetes. Expert Opin Emerg Drugs 2013; 18:55-70. [PMID: 23330907 DOI: 10.1517/14728214.2013.762356] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
INTRODUCTION The need for new approaches to manage the increasing numbers of patients with diabetes and their burden of complications is urgent. Of these, chronic kidney disease imposes some of the highest costs, both in dollars and in terms of human suffering. In individuals with diabetes, the presence and severity of kidney disease adversely affects their well-being, contributes to disease morbidity and increases their risk of a premature death. AREAS COVERED To collect information for the strategies previously or currently under investigation for managing kidney disease in patients with diabetes, a literature search was performed through the search engines PubMed and ClinicalTrials.gov. EXPERT OPINION Despite advancing knowledge on the pathogenesis of diabetic kidney disease, and promising effects in experimental models, at present there are no new drugs that come close to providing the solutions we desire for our patients. Even when used in combination with standard care, renal complications are at best only modestly reduced, at the considerable expense of additional pill burden and exposure to serious off-target effects. Some of the most exciting advances over the last decade, including thiazolidinediones, direct renin inhibitors, endothelin antagonists and most recently bardoxolone methyl have all fallen at this last hurdle. Better targeted ('smarter') drugs appear to be the best hope for renoprotective therapy.
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Affiliation(s)
- Merlin C Thomas
- Baker IDI Heart and Diabetes Institute, St Kilda Rd Central, PO Box 6492, Melbourne, VIC 8008, Australia.
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Miglio G, Rosa AC, Rattazzi L, Grange C, Camussi G, Fantozzi R. Protective effects of peroxisome proliferator-activated receptor agonists on human podocytes: proposed mechanisms of action. Br J Pharmacol 2013; 167:641-53. [PMID: 22594945 DOI: 10.1111/j.1476-5381.2012.02026.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE Peroxisome proliferator-activated receptor (PPAR) agonists exert anti-albuminuric effects. However, the nephroprotective effects of these drugs remain to be fully understood. We have investigated whether gemfibrozil, GW0742 and pioglitazone protect human podocytes against nutrient deprivation (ND)-induced cell death and the role of mitochondrial biogenesis as a cytoprotective process. EXPERIMENTAL APPROACH Immortalized human podocytes were pre-treated with the PPAR agonists and exposed to ND (5 h) under normoxia, hypoxia or in the presence of pyruvate. Cell death was measured at the end of the ND and of the recovery phase (24 h). Mitochondrial mass, cytochrome c oxidase (COX) subunits 1 and 4 were measured as markers of mitochondrial cell content, while membrane potential as an index of mitochondrial function. PGC-1α, NRF1 and Tfam expression was studied, as crucial regulators of mitochondrial biogenesis. KEY RESULTS Cell pre-treatment with gemfibrozil, GW0742, or pioglitazone significantly decreased the ND-induced cell loss, necrosis and apoptosis. These effects were attenuated by hypoxia and potentiated by pyruvate. Pre-treatment with these drugs significantly increased mitochondrial cell content, while it did not affect mitochondrial function. In all these experiments pioglitazone exerted significantly larger effects than gemfibrozil or GW0742. CONCLUSIONS AND IMPLICATIONS Gemfibrozil, GW0742 and pioglitazone may exert direct protective effects on human podocytes. Mitochondrial biogenesis is a cell response to the PPAR agonists related to their cytoprotective activity. These results provide a mechanistic support to the clinical evidence indicating PPAR agonists as disease-modifying agents for glomerular diseases.
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Affiliation(s)
- Gianluca Miglio
- Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Turin, Italy.
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Ristola M, Arpiainen S, Shimokawa T, Ra C, Tienari J, Saleem MA, Holthöfer H, Lehtonen S. Regulation of nephrin gene by the Ets transcription factor, GA-binding protein. Nephrol Dial Transplant 2012. [PMID: 23197680 DOI: 10.1093/ndt/gfs482] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Transcription factor GA-binding protein (GABP) is suggested to be involved in the formation of the neuromuscular junctions by regulating the transcription of synapse genes. Interestingly, neurons and podocytes share molecular and functional similarities that led us to investigate the expression and function of GABP in podocytes and its role in transcriptional regulation of nephrin, the key molecule of the podocyte slit diaphragm that is essential for normal glomerular ultrafiltration. METHODS The expression and localization of GABP in the rat and human kidney as well as in human embryonic kidney A293 cells and undifferentiated and differentiated human podocytes were analysed by immunoblotting and immunostaining. The role of GABP in activating the nephrin promoter was investigated by reporter gene assay and site-directed mutagenesis of the GABP-binding elements, and the interaction of GABP with the nephrin promoter was analysed by chromatin immunoprecipitation. The function of GABP in podocytes was studied by knocking down GABPα in differentiated human podocytes using lentiviral shRNA targeting GABPα. RESULTS GABP is expressed in the nuclei in rat and human glomeruli. In addition, in A293 cells and undifferentiated and differentiated human podocytes, GABP highly enriches in the nucleus. GABP activates and binds nephrin proximal promoter and Ets sites are essential for this activity. Knock-down of GABPα stimulates apoptosis in cultured podocytes. CONCLUSIONS The results show that GABP is expressed in podocytes and is involved in the regulation of nephrin gene expression. Furthermore, GABP may be important in the maintenance of podocyte function by regulating apoptosis.
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Affiliation(s)
- Mervi Ristola
- Department of Pathology, Haartman Institute, University of Helsinki, Helsinki, Finland
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16
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Reichenbach G, Starzinski-Powitz A, Sloane BF, Doll M, Kippenberger S, Bernd A, Kaufmann R, Meissner M. PPARα agonist Wy14643 suppresses cathepsin B in human endothelial cells via transcriptional, post-transcriptional and post-translational mechanisms. Angiogenesis 2012; 16:223-33. [PMID: 23096928 DOI: 10.1007/s10456-012-9314-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
Abstract
Cathepsin B has been shown to be important in angiogenesis; therefore, understanding its regulation in endothelial cells should provide fundamental information that will aid in the development of new treatment options. Peroxisome proliferator-activated receptors (PPARs) have been shown to have anti-inflammatory, anti-angiogenic and anti-tumorigenic properties. We explored the influence of a PPARα agonist on cathepsin B expression in human endothelial cells. The PPARα agonist, Wy14643, was found to inhibit cathepsin B protein expression. Further studies demonstrated the Wy14643-dependent but PPARα-independent suppression of cathepsin B. This has been previously described for other PPAR agonists. Wy14643 suppressed the accumulation of cathepsin B mRNA, which was accompanied by the selective suppression of a 5'-alternative splice variant. Consistent with these results, luciferase promoter assays and electrophoretic mobility shift analysis demonstrated that the suppression was facilitated by reduced binding of the transcription factors USF1/2 to an E-box within the cathepsin B promoter. Additionally, Wy14643 treatment resulted in a reduction in cathepsin B half-life, suggesting a posttranslational regulatory mechanism. Overall, our results suggest that the PPARα-dependent anti-angiogenic action of Wy14643 seems to be mediated, in part, by Wy14643-dependent but PPARα-independent regulation of cathepsin B expression.
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Affiliation(s)
- Gabi Reichenbach
- Department of Dermatology, Venereology and Allergology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
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Eisel F, Boosen M, Beck M, Heide H, Wittig I, Beck KF, Pfeilschifter J. Platelet-derived growth factor triggers PKA-mediated signalling by a redox-dependent mechanism in rat renal mesangial cells. Biochem Pharmacol 2012; 85:101-8. [PMID: 23103565 DOI: 10.1016/j.bcp.2012.10.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 10/15/2012] [Accepted: 10/16/2012] [Indexed: 10/27/2022]
Abstract
Inflammatory glomerular kidney diseases are often accompanied with a massive production of reactive oxygen species (ROS) that affect the function of the glomerular filtration barrier and contribute to mesangiolysis via the induction of cell death in mesangial cells. Intriguingly, ROS also trigger fine-tuned signalling processes that affect gene expression and cell proliferation or migration. To define such redox-driven signalling devices, a proteomics approach was performed to identify the formation of protein complexes induced by ROS. To this end, protein lysates of human podocytes were treated with or without hydrogen peroxide (250 μM). Thereafter cell lysates were subjected to diagonal 2D gel electrophoresis and putative redox-affected proteins were analysed by MS/MS analysis. Among others, the regulatory subunit of protein kinase A (PKA) could be identified that forms homodimers under oxidative conditions. To evaluate whether ROS dependent dimerization of PKA also occurs in a more physiological setting, rat mesangial cells were treated with platelet-derived growth factor-BB (PDGF-BB) to induce ROS formation. This regimen resulted in a redox dependent dimerization of the R-subunits of PKA. To demonstrate whether PDGF-BB induced ROS formation affects PKA dependent pathways, the effects of PDGF-BB on phosphorylation of serine 157 of vasodilator stimulated protein (VASP) a classical target of PKA were analysed. Interestingly PDGF-BB induced VASP phosphorylation in a ROS dependent manner but independent of changes in cAMP levels. Taken together, we demonstrate a redox-mediated activation of PKA by PDGF-BB thus highlighting a physiological role of ROS as regulator of PKA activity in rat mesangial cells.
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Affiliation(s)
- Florian Eisel
- Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany
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Khurana S, Bruggeman LA, Kao HY. Nuclear hormone receptors in podocytes. Cell Biosci 2012; 2:33. [PMID: 22995171 PMCID: PMC3543367 DOI: 10.1186/2045-3701-2-33] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 08/10/2012] [Indexed: 11/14/2022] Open
Abstract
Nuclear receptors are a family of ligand-activated, DNA sequence-specific transcription factors that regulate various aspects of animal development, cell proliferation, differentiation, and homeostasis. The physiological roles of nuclear receptors and their ligands have been intensively studied in cancer and metabolic syndrome. However, their role in kidney diseases is still evolving, despite their ligands being used clinically to treat renal diseases for decades. This review will discuss the progress of our understanding of the role of nuclear receptors and their ligands in kidney physiology with emphasis on their roles in treating glomerular disorders and podocyte injury repair responses.
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Affiliation(s)
- Simran Khurana
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU) and the Comprehensive Cancer Center of CWRU, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
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Lee EY, Kim GT, Hyun M, Kim S, Seok S, Choi R, Lee MY, Chung CH. Peroxisome proliferator-activated receptor- activation ameliorates albuminuria by preventing nephrin loss and restoring podocyte integrity in Type 2 diabetes. Nephrol Dial Transplant 2012; 27:4069-79. [DOI: 10.1093/ndt/gfs358] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Khurana S, Chakraborty S, Lam M, Liu Y, Su YT, Zhao X, Saleem MA, Mathieson PW, Bruggeman LA, Kao HY. Familial focal segmental glomerulosclerosis (FSGS)-linked α-actinin 4 (ACTN4) protein mutants lose ability to activate transcription by nuclear hormone receptors. J Biol Chem 2012; 287:12027-35. [PMID: 22351778 DOI: 10.1074/jbc.m112.345421] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mutations in α-actinin 4 (ACTN4) are linked to familial forms of focal segmental glomerulosclerosis (FSGS), a kidney disease characterized by proteinuria due to podocyte injury. The mechanisms underlying ACTN4 mutant-associated FSGS are not completely understood. Although α-actinins are better known to cross-link actin filaments and modulate cytoskeletal organization, we have previously shown that ACTN4 interacts with transcription factors including estrogen receptor and MEF2s and potentiates their transcriptional activity. Nuclear receptors including retinoic acid receptor (RAR) have been proposed to play a protective role in podocytes. We show here that ACTN4 interacts with and enhances transcriptional activation by RARα. In addition, FSGS-linked ACTN4 mutants not only mislocalized to the cytoplasm, but also lost their ability to associate with nuclear receptors. Consequently, FSGS-linked ACTN4 mutants failed to potentiate transcriptional activation by nuclear hormone receptors in podocytes. In addition, overexpression of these mutants suppressed the transcriptional activity mediated by endogenous wild-type ACTN4 possibly by a cytoplasmic sequestration mechanism. Our data provide the first link between FSGS-linked ACTN4 mutants and transcriptional activation by nuclear receptor such as RARα and peroxisome proliferator-activated receptor γ.
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Affiliation(s)
- Simran Khurana
- Department of Biochemistry, School of Medicine, Case Western Reserve University and Research Institute of University Hospitals of Cleveland, Cleveland, Ohio 44106, USA
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The renoprotective actions of peroxisome proliferator-activated receptors agonists in diabetes. PPAR Res 2012; 2012:456529. [PMID: 22448165 PMCID: PMC3289856 DOI: 10.1155/2012/456529] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 11/21/2011] [Accepted: 11/21/2011] [Indexed: 12/17/2022] Open
Abstract
Pharmaceutical agonists of peroxisome proliferator-activated receptors (PPARs) are widely used in the management of type 2 diabetes, chiefly as lipid-lowering agents and oral hypoglycaemic agents. Although most of the focus has been placed on their cardiovascular effects, both positive and negative, these agents also have significant renoprotective actions in the diabetic kidney. Over and above action on metabolic control and effects on blood pressure, PPAR agonists also appear to have independent effects on a number of critical pathways that are implicated in the development and progression of diabetic kidney disease, including oxidative stress, inflammation, hypertrophy, and podocyte function. This review will examine these direct and indirect actions of PPAR agonists in the diabetic kidney and explore recent findings of clinical trials of PPAR agonists in patients with diabetes.
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Thomas MC, Groop PH. New approaches to the treatment of nephropathy in diabetes. Expert Opin Investig Drugs 2011; 20:1057-71. [DOI: 10.1517/13543784.2011.591785] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Peroxisome proliferator-activated receptor-α is renoprotective in doxorubicin-induced glomerular injury. Kidney Int 2011; 79:1302-11. [PMID: 21368746 DOI: 10.1038/ki.2011.17] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Doxorubicin (DOX) is an anthracycline antibiotic utilized in antitumor therapy; however, its clinical use is frequently impeded by renal toxic effects. As peroxisome proliferator-activated receptor-α (PPAR-α) has renoprotective effects in drug-related kidney injuries, we tested its ability to inhibit DOX-induced renal injury. Although both male PPAR-α knockout mice and their wild-type littermates (pure 129/SvJ background) had significant proteinuria 4 weeks after DOX treatment, those with deletion of PPAR-α had more severe proteinuria. This was associated with more serious podocyte foot process effacement compared with wild-type mice. In contrast, the PPAR-α agonist fenofibrate effectively reduced proteinuria and attenuated DOX-induced podocyte foot process effacement. Consistently, glomerular nephrin expression was significantly lower in the knockout compared with wild-type mice following DOX treatment. Fenofibrate therapy significantly blunted the reduction in glomerular nephrin levels in DOX-treated wild-type mice. In cultured podocytes, DOX induced apoptosis, increased cleaved caspase-3 levels, and decreased Bcl-2 expression, all attenuated by pretreatment with fenofibrate. Thus, PPAR-α deficiency exacerbates DOX-related renal injury, in part, due to increased podocyte apoptosis.
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Miglio G, Rosa AC, Rattazzi L, Grange C, Collino M, Camussi G, Fantozzi R. The subtypes of peroxisome proliferator-activated receptors expressed by human podocytes and their role in decreasing podocyte injury. Br J Pharmacol 2011; 162:111-25. [PMID: 20840470 PMCID: PMC3012410 DOI: 10.1111/j.1476-5381.2010.01032.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/15/2010] [Accepted: 08/01/2010] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors, and three subtypes (α, β and γ) have been identified. PPAR activation has been reported to decrease renal injury and markers of glomerular dysfunction in models of renal ischemia/reperfusion (I/R). However, both the I/R effects and the effects of PPAR agonists on podocytes, an integral cellular part of the glomerular filtration barrier, remain to be established. EXPERIMENTAL APPROACH By using oxygen/glucose deprivation-reoxygenation as an in vitro model that mimics in vivo I/R, the effects of PPAR agonists on podocyte death were compared. Human immortalized podocytes were treated with gemfibrozil, GW0742, pioglitazone or rosiglitazone, as a single or repeated challenge. Cell loss, necrotic and apoptotic cell death were measured. KEY RESULTS Only the repeated treatment with each PPAR agonist significantly prevented cell death, mainly by decreasing apoptosis. In comparison, in a model of serum deprivation-induced apoptosis, both treatments were effective, although the repeated treatment achieved the more pronounced effect. Finally, our results showed that preservation of Bcl-2, Bax and nephrin expression accompanied the anti-apoptotic effects exerted by PPAR agonists in human podocytes. CONCLUSION AND IMPLICATIONS These findings contribute to clarification of the pathophysiological role of renal PPARs and suggest that selective PPARα, PPARβ or PPARγ agonists may exert similar protective effects on podocytes by decreasing apoptotic cell death.
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Affiliation(s)
- Gianluca Miglio
- Department of Anatomy, Pharmacology and Forensic Medicine, University of Turin, Turin, Italy.
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Cybulsky AV, Takano T, Papillon J, Guillemette J, Herzenberg AM, Kennedy CRJ. Podocyte injury and albuminuria in mice with podocyte-specific overexpression of the Ste20-like kinase, SLK. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:2290-9. [PMID: 20889563 DOI: 10.2353/ajpath.2010.100263] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SLK expression and activity are increased during kidney development and recovery from renal ischemia-reperfusion injury. In cultured cells, SLK promotes F-actin destabilization as well as apoptosis, partially via the p38 kinase pathway. To better understand the effects of SLK in vivo, a transgenic mouse model was developed where SLK was expressed in a podocyte-specific manner using the mouse nephrin promoter. Offspring of four founder mice carried the SLK transgene. Among male transgenic mice, 66% developed albuminuria at approximately 3 months of age, and the albuminuric mice originated from three of four founders. Overall, the male transgenic mice demonstrated about fivefold greater urinary albumin/creatinine compared with male non-transgenic mice. Transgenic and non-transgenic female mice did not develop albuminuria, suggesting that females were less susceptible to glomerular filtration barrier damage than their male counterparts. In transgenic mice, electron microscopy revealed striking podocyte injury, including poorly formed or effaced foot processes, and edematous and vacuolated cell bodies. By immunoblotting, nephrin expression was decreased in glomeruli of the albuminuric transgenic mice. Activation-specific phosphorylation of p38 was increased in transgenic mice compared with non-transgenic animals. Glomeruli of SLK transgenic mice showed around 30% fewer podocytes, and a reduction in F-actin compared with control glomeruli. Thus, podocyte SLK overexpression in vivo results in injury and podocyte loss, consistent with the effects of SLK in cultured cells.
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Affiliation(s)
- Andrey V Cybulsky
- Department of Medicine, McGill University Health Centre, McGill University, Division of Nephrology, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, Quebec, Canada H3A 1A1.
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Meissner M, Hrgovic I, Doll M, Naidenow J, Reichenbach G, Hailemariam-Jahn T, Michailidou D, Gille J, Kaufmann R. Peroxisome proliferator-activated receptor {delta} activators induce IL-8 expression in nonstimulated endothelial cells in a transcriptional and posttranscriptional manner. J Biol Chem 2010; 285:33797-804. [PMID: 20592029 DOI: 10.1074/jbc.m110.137943] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that are implicated in the regulation of lipid and glucose homeostasis. PPAR agonists have been shown to control inflammatory processes, in part by inhibiting distinct proinflammatory genes (e.g. Il-1β and IFN-γ). IL-8 is a member of the proinflammatory chemokine family that is important for various functions, such as mediating the adhesion of eosinophilic granulocytes onto endothelial cells. The influence of PPARδ activators on the expression of IL-8 in noninduced quiescent endothelial cells is unclear. Therefore, we explored the influence of PPARδ activators on the expression of IL-8 in nonstimulated endothelial cells. PPARδ agonists induce IL-8 expression in human umbilical vein endothelial cells. This induction is demonstrated at the level of both protein and mRNA expression. Transcriptional activation studies using IL-8 reporter gene constructs and DNA binding assays revealed that PPARδ agonists mediated their effects via an NFκB binding site. It is well known that IL-8 is also regulated by mRNA stability. To provide further evidence for this concept, we performed mRNA stability assays and found that PPARδ agonists induce the mRNA stability of IL-8. In addition, we showed that PPARδ agonists induce the phosphorylation of ERK1/2 and p38, which are known to be involved in the increase of mRNA stability. The inhibition of these MAPK signaling pathways resulted in a significant suppression of the induced IL-8 expression and the reduced mRNA stability. Therefore, our data provide the first evidence that PPARδ induces IL-8 expression in nonstimulated endothelial cells via transcriptional as well as posttranscriptional mechanisms.
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Affiliation(s)
- Markus Meissner
- Department of Dermatology, Johann Wolfgang Goethe-Universität, D-60590 Frankfurt am Main, Germany.
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Choi HJ, Yang H, Park SH, Moon Y. HuR/ELAVL1 RNA binding protein modulates interleukin-8 induction by muco-active ribotoxin deoxynivalenol. Toxicol Appl Pharmacol 2009; 240:46-54. [DOI: 10.1016/j.taap.2009.06.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 05/28/2009] [Accepted: 06/26/2009] [Indexed: 10/20/2022]
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Tarabra E, Giunti S, Barutta F, Salvidio G, Burt D, Deferrari G, Gambino R, Vergola D, Pinach S, Perin PC, Camussi G, Gruden G. Effect of the monocyte chemoattractant protein-1/CC chemokine receptor 2 system on nephrin expression in streptozotocin-treated mice and human cultured podocytes. Diabetes 2009; 58:2109-18. [PMID: 19587356 PMCID: PMC2731530 DOI: 10.2337/db08-0895] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Monocyte chemoattractant protein-1 (MCP-1), a chemokine binding to the CC chemokine receptor 2 (CCR2) and promoting monocyte infiltration, has been implicated in the pathogenesis of diabetic nephropathy. To assess the potential relevance of the MCP-1/CCR2 system in the pathogenesis of diabetic proteinuria, we studied in vitro if MCP-1 binding to the CCR2 receptor modulates nephrin expression in cultured podocytes. Moreover, we investigated in vivo if glomerular CCR2 expression is altered in kidney biopsies from patients with diabetic nephropathy and whether lack of MCP-1 affects proteinuria and expression of nephrin in experimental diabetes. RESEARCH DESIGN AND METHODS Expression of nephrin was assessed in human podocytes exposed to rh-MCP-1 by immunofluorescence and real-time PCR. Glomerular CCR2 expression was studied in 10 kidney sections from patients with overt nephropathy and eight control subjects by immunohistochemistry. Both wild-type and MCP-1 knockout mice were made diabetic with streptozotocin. Ten weeks after the onset of diabetes, albuminuria and expression of nephrin, synaptopodin, and zonula occludens-1 were examined by immunofluorescence and immunoblotting. RESULTS In human podocytes, MCP-1 binding to the CCR2 receptor induced a significant reduction in nephrin both mRNA and protein expression via a Rho-dependent mechanism. The MCP-1 receptor, CCR2, was overexpressed in the glomerular podocytes of patients with overt nephropathy. In experimental diabetes, MCP-1 was overexpressed within the glomeruli and the absence of MCP-1 reduced both albuminuria and downregulation of nephrin and synaptopodin. CONCLUSIONS These findings suggest that the MCP-1/CCR2 system may be relevant in the pathogenesis of proteinuria in diabetes.
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Affiliation(s)
- Elena Tarabra
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
| | - Sara Giunti
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
- Emergency Medicine Division, Umberto Parini Hospital, Aosta, Italy
| | - Federica Barutta
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
| | | | - Davina Burt
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
| | | | - Roberto Gambino
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
| | | | - Silvia Pinach
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
| | - Paolo Cavallo Perin
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
| | - Giovanni Camussi
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
| | - Gabriella Gruden
- Diabetic Nephropathy Laboratory, Department of Internal Medicine, University of Turin, Italy
- Corresponding author: Gabriella Gruden,
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Ristola M, Arpiainen S, Saleem MA, Mathieson PW, Welsh GI, Lehtonen S, Holthöfer H. Regulation of Neph3 gene in podocytes--key roles of transcription factors NF-kappaB and Sp1. BMC Mol Biol 2009; 10:83. [PMID: 19703278 PMCID: PMC2736951 DOI: 10.1186/1471-2199-10-83] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 08/24/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Neph3 (filtrin) is expressed in the glomerular podocytes where it localizes at the specialized cell adhesion structures of the foot processes called slit diaphragms which form the outermost layer of the glomerular filtration barrier. Neph3 protein shows homology and structural similarity to Neph1, Neph2 and nephrin, which all are crucial for maintaining the normal glomerular ultrafiltration function. The exact function of Neph3 in the kidney is not known but we have previously shown that the level of Neph3 mRNA is decreased in proteinuric diseases. This suggests that Neph3 may play a role in the pathogenesis of kidney damage, and emphasizes the need to analyze the regulatory mechanisms of Neph3 gene. In this study we investigated the transcriptional regulation of Neph3 gene by identifying transcription factors that control Neph3 expression. RESULTS We cloned and characterized approximately 5 kb fragment upstream of the Neph3 gene. Neph3 proximal promoter near the transcription start site was found to be devoid of TATA and CAAT boxes, but to contain a highly GC-rich area. Using promoter reporter gene constructs, we localized the main activating regulatory region of Neph3 gene in its proximal promoter region from -105 to -57. Within this region, putative transcription factor binding sites for NF-kappaB and Sp1 were found by computational analysis. Mutational screening indicated that NF-kappaB and Sp1 response elements are essential for the basal transcriptional activity of the Neph3 promoter. Co-transfection studies further showed that NF-kappaB and Sp1 regulate Neph3 promoter activity. In addition, overexpression of NF-kappaB increased endogenous Neph3 gene expression. Chromatin immunoprecipitation assay using cultured human podocytes demonstrated that both NF-kappaB and Sp1 interact with the Neph3 promoter. CONCLUSION Our results show that NF-kappaB and Sp1 are key regulators of Neph3 expression at the basal level in podocytes, therefore providing new insight into the molecular mechanisms that contribute to the expression of Neph3 gene.
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Affiliation(s)
- Mervi Ristola
- Department of Bacteriology and Immunology, Haartman Institute, P,O, Box 21, 00014 University of Helsinki, Finland.
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Hahn WH, Cho BS, Kim SD, Kim SK, Kang S. Interleukin-1 cluster gene polymorphisms in childhood IgA nephropathy. Pediatr Nephrol 2009; 24:1329-36. [PMID: 19280228 DOI: 10.1007/s00467-009-1146-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 01/23/2009] [Accepted: 02/03/2009] [Indexed: 11/28/2022]
Abstract
We have carried out a study with the aim of investigating the association between single nucleotide polymorphisms (SNPs) of the IL-1 gene cluster and childhood IgA nephropathy (IgAN). SNPs of the IL-1 alpha, IL-1 beta, and IL-1 receptor antagonist (RN) genes (IL1A, IL1B, and IL1RN, respectively) were analyzed in 182 patients with childhood IgAN and in 500 healthy controls. The IgAN patients were also dichotomized and compared with respect to proteinuria (<4 mg and >or=4 mg/m(2) per hour, respectively), the presence or absence of podocyte foot process effacement, and the presence of pathologically early and advanced disease markers, such as interstitial fibrosis, tubular atrophy, or global sclerosis. Significant differences in SNP frequencies were observed for the IL1B and IL1RN genes (rs1143627, rs3917356, and rs1143633 in the IL1B gene, and rs928940, rs439154, and rs315951 in the IL1RN gene). Moreover, rs1143627, rs3917356, and rs1143633 of IL1B were found to be significantly associated with the presence of podocyte foot process effacement. Our results suggest that the IL1B and IL1RN genes are associated with increased susceptibility to IgAN in children. They also suggest that the development of proteinuria in IgAN is related to IL1A and that podocyte foot process effacement is associated with IL1B.
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Affiliation(s)
- Won Ho Hahn
- Department of Pediatrics, East West Kidney Diseases Research Institute, School of Medicine, Kyung Hee University, Dondaemun-gu, Hoegi-dong #1, Seoul, 130-701, Korea
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Hypo-responsiveness of interleukin-8 production in human embryonic epithelial intestine 407 cells independent of NF-κB pathway: New lessons from endotoxin and ribotoxic deoxynivalenol. Toxicol Appl Pharmacol 2008; 231:94-102. [DOI: 10.1016/j.taap.2008.03.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 03/04/2008] [Accepted: 03/25/2008] [Indexed: 11/19/2022]
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Amelioration of anti-cancer agent adriamycin-induced nephrotic syndrome in rats by Wulingsan (Gorei-San), a blended traditional Chinese herbal medicine. Food Chem Toxicol 2008; 46:1452-60. [DOI: 10.1016/j.fct.2007.12.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 11/28/2007] [Accepted: 12/03/2007] [Indexed: 12/16/2022]
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Takano Y, Yamauchi K, Hiramatsu N, Kasai A, Hayakawa K, Yokouchi M, Yao J, Kitamura M. Recovery and maintenance of nephrin expression in cultured podocytes and identification of HGF as a repressor of nephrin. Am J Physiol Renal Physiol 2007; 292:F1573-82. [PMID: 17244893 DOI: 10.1152/ajprenal.00423.2006] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cultured podocytes easily lose expression of nephrin. In this report, we developed optimum media for recovery and maintenance of nephrin gene expression in murine podocytes. Using reporter podocytes, we found that activity of the nephrin gene promoter was enhanced by DMEM/F12 or α-MEM compared with RPMI-1640. In any of these basal media, addition of 1,25-dihydroxyvitamin D3, all- trans-retinoic acid or dexamethasone significantly increased activity of the nephrin promoter. The effects of the supplemental components were synergistic, and the maximum activation was achieved by DMEM/F12 supplemented with three agents. This culture medium was designated as vitamin D3, retinoic acid and dexamethasone-supplemented DMEM/F12 (VRADD). In reporter podocytes that express nephrin, VRADD induced activation of the nephrin gene promoter up to 60-fold. Even in podocytes that have lost nephrin expression during multiple passages, expression of nephrin mRNA was dramatically recovered by VRADD. However, VRADD caused damage of podocytes in prolonged cultures, which was avoided in the absence of dexamethasone (designated as VRAD). VRAD maintained expression of nephrin for extended periods, which was associated with the differentiated phenotype of podocytes. Using the VRAD-primed podocytes, we revealed that expression of nephrin mRNA as well as nephrin promoter activity was suppressed by a putative dedifferentiation factor of podocytes, hepatocyte growth factor.
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Affiliation(s)
- Yosuke Takano
- Departments of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
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Jackson TC, Mi Z, Bastacky SI, McHale T, Melhem MF, Sonalker PA, Tofovic SP, Jackson EK. PPAR? agonists improve renal preservation in kidneys subjected to chronic in vitro perfusion: interaction with mannitol. Transpl Int 2007; 20:277-90. [PMID: 17291221 DOI: 10.1111/j.1432-2277.2006.00431.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We developed methods for prolonged (12 h), sterile, normothermic perfusion of rat kidneys and screened compounds for renal preservation including: mitochondrial transition pore inhibitor (decylubiquinone); caspase inhibitor (Z-VAD); peroxisome proliferator-activated receptor-alpha (PPARalpha) agonists (gemfibrozil, WY-14643); antioxidants (trolox, luteolin, quercetin); growth factors (HGF, PDGF, EGF, IGF-1, VEGF, transferrin); calpain inhibitor (Z-Val-Phe-CHO); calmodulin inhibitor (W7); K(ATP) opener (minoxidil, minoxidil sulfate); PARP inhibitor (3-aminobenzamide); calcium channel blocker (verapamil); V(2) agonist (DDAVP); diuretics (acetazolamide, hydrochlorothiazide, furosemide, mannitol); peroxisome proliferator-activated receptor-beta agonist (L-165041); dopamine agonist (dopamine); essential fatty acid (linolenic acid); beta-NAD; urea; uric acid; and aldosterone. In pilot studies, only PPARalpha agonists and mannitol provided promising results. Accordingly, these agents were investigated further. Fifteen rat kidneys were perfused for 12 h with L-15 media at 37 degrees C in the absence or presence of mannitol, gemfibrozil, gemfibrozil + mannitol or WY-14643. Chronic perfusion in untreated kidneys caused destruction of glomerular and tubular architecture (light and electron microscopy), disappearance of Na(+)-K(+)-ATPase-alpha(1) (Western blotting), and apoptosis (Apoptag staining). Gemfibrozil and WY-14643 marginally improved some biomarkers of renal preservation. However, the combination of gemfibrozil with mannitol markedly improved all parameters of renal preservation. We conclude that PPARalpha agonists, particularly when combined with mannitol, protect organs from normothermic, perfusion-induced damage.
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Affiliation(s)
- Travis C Jackson
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219-3130, USA
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Takano Y, Yamauchi K, Hayakawa K, Hiramatsu N, Kasai A, Okamura M, Yokouchi M, Shitamura A, Yao J, Kitamura M. Transcriptional suppression of nephrin in podocytes by macrophages: roles of inflammatory cytokines and involvement of the PI3K/Akt pathway. FEBS Lett 2007; 581:421-6. [PMID: 17239861 DOI: 10.1016/j.febslet.2006.12.051] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 12/20/2006] [Accepted: 12/22/2006] [Indexed: 11/28/2022]
Abstract
Expression of nephrin, a crucial component of the glomerular slit diaphragm, is downregulated in patients with proteinuric glomerular diseases. Using conditionally immortalized reporter podocytes, we found that bystander macrophages as well as macrophage-derived cytokines IL-1beta and TNF-alpha markedly suppressed activity of the nephrin gene promoter in podocytes. The cytokine-initiated repression was reversible, observed on both basal and inducible expression, independent of Wilms' tumor suppressor WT1, and caused in part via activation of the phosphatidylinositol-3-kinase/Akt pathway. These results indicated a novel mechanism by which activated macrophages participate in the induction of proteinuria in glomerular diseases.
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Affiliation(s)
- Yosuke Takano
- Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan
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Pätäri-Sampo A, Ihalmo P, Holthöfer H. Molecular basis of the glomerular filtration: nephrin and the emerging protein complex at the podocyte slit diaphragm. Ann Med 2006; 38:483-92. [PMID: 17101539 DOI: 10.1080/07853890600978149] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
For more than three decades, the molecular composition of the interpodocyte slit diaphragm of the glomerular filtration barrier has remained elusive. The first electron microscopic studies described the slit diaphragm as a porous, 'zipper-like' structure, but it was not until 1998 that the first transmembrane molecule of the slit diaphragm was identified: nephrin is a cell surface receptor of the immunoglobulin superfamily participating in cell-cell adhesion and signaling functions. Mutations in nephrin lead to the congenital nephrotic syndrome of the Finnish type, suggesting that nephrin is of pivotal importance for maintaining the filtration barrier. In recent years, the mapping of the genetic background of other inherited and acquired nephropathies and generation of transgenic animal models have led to a beginning of a new era in nephrology, possibly promising new targeted therapies and advanced diagnostics. This review article will briefly summarize the main findings that explain the molecular architecture of the glomerular filter itself and causes of some glomerular diseases that lead to proteinuria and, eventually, to renal failure.
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Affiliation(s)
- Anu Pätäri-Sampo
- Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland
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