1
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Williamson CR, Jones N. Reduced Nephrin Tyrosine Phosphorylation Enhances Insulin Secretion and Increases Glucose Tolerance With Age. Endocrinology 2024; 165:bqae078. [PMID: 38954536 PMCID: PMC11247170 DOI: 10.1210/endocr/bqae078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/31/2024] [Accepted: 06/27/2024] [Indexed: 07/04/2024]
Abstract
BACKGROUND Nephrin is a transmembrane protein with well-established signaling roles in kidney podocytes, and a smaller set of secretory functions in pancreatic β cells are implicated in diabetes. Nephrin signaling is mediated in part through its 3 cytoplasmic YDxV motifs, which can be tyrosine phosphorylated by high glucose and β cell injuries. Although in vitro studies demonstrate these phosphorylated motifs can regulate β cell vesicle trafficking and insulin release, in vivo evidence of their role in this cell type remains to be determined. METHODS To further explore the role of nephrin YDxV phosphorylation in β cells, we used a mouse line with tyrosine to phenylalanine substitutions at each YDxV motif (nephrin-Y3F) to inhibit phosphorylation. We assessed islet function via primary islet glucose-stimulated insulin secretion assays and oral glucose tolerance tests. RESULTS Nephrin-Y3F mice successfully developed pancreatic endocrine and exocrine tissues with minimal structural differences. Unexpectedly, male and female nephrin-Y3F mice showed elevated insulin secretion, with a stronger increase observed in male mice. At 8 months of age, no differences in glucose tolerance were observed between wild-type (WT) and nephrin-Y3F mice. However, aged nephrin-Y3F mice (16 months of age) demonstrated more rapid glucose clearance compared to WT controls. CONCLUSION Taken together, loss of nephrin YDxV phosphorylation does not alter baseline islet function. Instead, our data suggest a mechanism linking impaired nephrin YDxV phosphorylation to improved islet secretory ability with age. Targeting nephrin phosphorylation could provide novel therapeutic opportunities to improve β cell function.
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Affiliation(s)
- Casey R Williamson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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2
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Kleibert M, Zygmunciak P, Łakomska K, Mila K, Zgliczyński W, Mrozikiewicz-Rakowska B. Insight into the Molecular Mechanism of Diabetic Kidney Disease and the Role of Metformin in Its Pathogenesis. Int J Mol Sci 2023; 24:13038. [PMID: 37685845 PMCID: PMC10487922 DOI: 10.3390/ijms241713038] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/10/2023] [Accepted: 08/13/2023] [Indexed: 09/10/2023] Open
Abstract
Diabetic kidney disease (DKD) is one of the leading causes of death among patients diagnosed with diabetes mellitus. Despite the growing knowledge about the pathogenesis of DKD, we still do not have effective direct pharmacotherapy. Accurate blood sugar control is essential in slowing down DKD. It seems that metformin has a positive impact on kidneys and this effect is not only mediated by its hypoglycemic action, but also by direct molecular regulation of pathways involved in DKD. The molecular mechanism of DKD is complex and we can distinguish polyol, hexosamine, PKC, and AGE pathways which play key roles in the development and progression of this disease. Each of these pathways is overactivated in a hyperglycemic environment and it seems that most of them may be regulated by metformin. In this article, we summarize the knowledge about DKD pathogenesis and the potential mechanism of the nephroprotective effect of metformin. Additionally, we describe the impact of metformin on glomerular endothelial cells and podocytes, which are harmed in DKD.
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Affiliation(s)
- Marcin Kleibert
- Chair and Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, 02-097 Warsaw, Poland;
| | - Przemysław Zygmunciak
- Faculty of Medicine, Medical University of Warsaw, 02-091 Warsaw, Poland; (P.Z.); (K.M.)
| | - Klaudia Łakomska
- Faculty of Medicine, Wroclaw Medical University, 50-367 Wroclaw, Poland;
| | - Klaudia Mila
- Faculty of Medicine, Medical University of Warsaw, 02-091 Warsaw, Poland; (P.Z.); (K.M.)
| | - Wojciech Zgliczyński
- Department of Endocrinology, Centre of Postgraduate Medical Education, Bielanski Hospital, 01-809 Warsaw, Poland;
| | - Beata Mrozikiewicz-Rakowska
- Department of Endocrinology, Centre of Postgraduate Medical Education, Bielanski Hospital, 01-809 Warsaw, Poland;
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3
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Infante B, Conserva F, Pontrelli P, Leo S, Stasi A, Fiorentino M, Troise D, dello Strologo A, Alfieri C, Gesualdo L, Castellano G, Stallone G. Recent advances in molecular mechanisms of acute kidney injury in patients with diabetes mellitus. Front Endocrinol (Lausanne) 2023; 13:903970. [PMID: 36686462 PMCID: PMC9849571 DOI: 10.3389/fendo.2022.903970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 12/14/2022] [Indexed: 01/06/2023] Open
Abstract
Several insults can lead to acute kidney injury (AKI) in native kidney and transplant patients, with diabetes critically contributing as pivotal risk factor. High glucose per se can disrupt several signaling pathways within the kidney that, if not restored, can favor the instauration of mechanisms of maladaptive repair, altering kidney homeostasis and proper function. Diabetic kidneys frequently show reduced oxygenation, vascular damage and enhanced inflammatory response, features that increase the kidney vulnerability to hypoxia. Importantly, epidemiologic data shows that previous episodes of AKI increase susceptibility to diabetic kidney disease (DKD), and that patients with DKD and history of AKI have a generally worse prognosis compared to DKD patients without AKI; it is therefore crucial to monitor diabetic patients for AKI. In the present review, we will describe the causes that contribute to increased susceptibility to AKI in diabetes, with focus on the molecular mechanisms that occur during hyperglycemia and how these mechanisms expose the different types of resident renal cells to be more vulnerable to maladaptive repair during AKI (contrast- and drug-induced AKI). Finally, we will review the list of the existing candidate biomarkers of diagnosis and prognosis of AKI in patients with diabetes.
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Affiliation(s)
- Barbara Infante
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Francesca Conserva
- Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Paola Pontrelli
- Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Serena Leo
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Alessandra Stasi
- Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Marco Fiorentino
- Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Dario Troise
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | | | - Carlo Alfieri
- Nephrology, Dialysis and Renal Transplant Unit, Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Loreto Gesualdo
- Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Giuseppe Castellano
- Nephrology, Dialysis and Renal Transplant Unit, Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Giovanni Stallone
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
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4
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Alqallaf A, Swan P, Docherty NG. Renal insulin resistance in type 2 diabetes mellitus and progression of chronic kidney disease: potential pathogenic mechanisms. Expert Rev Endocrinol Metab 2022; 17:523-532. [PMID: 36203374 DOI: 10.1080/17446651.2022.2131534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 09/28/2022] [Indexed: 01/06/2023]
Abstract
INTRODUCTION A bidirectional association exists between insulin resistance (IR) and chronic kidney disease (CKD) in Type 2 Diabetes Mellitus (T2DM). Baseline measures of IR are predictive of CKD progression, and uremia in progressive CKD is itself, in turn, associated with a worsening of IR. Pre-clinical research reveals that intrinsic IR in glomerular podocytes and the renal tubule may serve as a pathogenic driver of CKD in T2DM. AREAS COVERED The present manuscript takes as its point of departure, the recently identified prognostic utility of severe insulin resistance as a predictor of CKD in T2DM. Findings from a series of studies describing the association of IR with pathological alterations in both established, and less commonly assessed dynamic measures of renal impairment are discussed. Drawing upon the pre-clinical mechanistic evidence base, the cellular and molecular basis of intrinsic renal IR as a promoter of CKD is considered. EXPERT OPINION Measurement of insulin sensitivity may add value to profiling of renal risk in T2DM. Rational selection of therapeutic strategies targeting the enhancement of insulin sensitivity merits special attention regarding the personalized management of CKD in insulin resistance predominant T2DM.
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Affiliation(s)
- Alrataj Alqallaf
- Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, School of Medicine, University College Dublin, Dublin, Ireland
| | - Patrick Swan
- Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, School of Medicine, University College Dublin, Dublin, Ireland
| | - Neil G Docherty
- Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Research, School of Medicine, University College Dublin, Dublin, Ireland
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5
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Sinha S, Haque M. Insulin Resistance and Type 2 Diabetes Mellitus: An Ultimatum to Renal Physiology. Cureus 2022; 14:e28944. [PMID: 36111327 PMCID: PMC9462660 DOI: 10.7759/cureus.28944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2022] [Indexed: 11/24/2022] Open
Abstract
Insulin resistance (IR) is stated as diminished insulin action regardless of hyperinsulinemia. The usual target organs for insulin activities are the liver, skeletal muscle, and adipose tissue. Hence, the vasculature and kidneys are nonconventional target organs as the impacts of insulin on these are comparatively separate from other conventional target organs. Vasodilation is achieved by raising endothelial nitric oxide (NO) generation by initiating the phosphoinositide 3-kinase (PI3K) pathway. In insulin-nonresponsive conditions, this process is defective, and there is increased production of endothelin-1 through the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, which predominates the NO effects, causing vasoconstriction. Renal tubular cells and podocytes have insulin receptors, and their purposeful importance has been studied, which discloses critical acts of insulin signaling in podocyte survivability and tubular action. Diabetic nephropathy (DN) is a prevalent problem in individuals with hypertension, poor glycemic management, hereditary susceptibility, or glomerular hyperfiltration. DN could be a significant contributing factor to end-stage renal disease (ESRD) that results from chronic kidney disease (CKD). IR and diabetes mellitus (DM) are the constituents of syndrome X and are accompanied by CKD progression. IR performs a key part in syndrome X leading to CKD. However, it is indistinct whether IR individually participates in enhancing the threat to CKD advancement rather than CKD complexity. CKD is an extensive public health problem affecting millions of individuals worldwide. The tremendous spread of kidney disease intensifies people’s health impacts related to communicable and noncommunicable diseases. Chronic disease regulator policies do not include CKD at global, local, and/or general levels. Improved knowledge of the character of CKD-associated problems might aid in reforming diagnosis, prevention, and management.
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6
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Lausecker F, Koehler S, Fresquet M, Naylor RW, Tian P, Wanner N, Braun F, Butt L, Huber TB, Lennon R. Integrating basic science with translational research: the 13th International Podocyte Conference 2021. Kidney Int 2022; 102:708-719. [PMID: 35964799 PMCID: PMC9386279 DOI: 10.1016/j.kint.2022.07.021] [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: 05/12/2022] [Revised: 07/20/2022] [Accepted: 07/26/2022] [Indexed: 11/30/2022]
Abstract
The 13th International Podocyte Conference was held in Manchester, UK, and online from July 28 to 30, 2021. Originally planned for 2020, this biannual meeting was postponed by a year because of the coronavirus disease 2019 (COVID-19) pandemic and proceeded as an innovative hybrid meeting. In addition to in-person attendance, online registration was offered, and this attracted 490 conference registrations in total. As a Podocyte Conference first, a day for early-career researchers was introduced. This premeeting included talks from graduate students and postdoctoral researchers. It gave early career researchers the opportunity to ask a panel, comprising academic leaders and journal editors, about career pathways and the future for podocyte research. The main meeting over 3 days included a keynote talk and 4 focused sessions each day incorporating invited talks, followed by selected abstract presentations, and an open panel discussion. The conference concluded with a Patient Day, which brought together patients, clinicians, researchers, and industry representatives. The Patient Day was an interactive and diverse day. As well as updates on improving diagnosis and potential new therapies, the Patient Day included a PodoArt competition, exercise and cooking classes with practical nutrition advice, and inspirational stories from patients and family members. This review summarizes the exciting science presented during the 13th International Podocyte Conference and demonstrates the resilience of researchers during a global pandemic.
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Affiliation(s)
- Franziska Lausecker
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Sybille Koehler
- Biomedical Sciences, University of Edinburgh, Edinburgh, UK; III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maryline Fresquet
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Richard W Naylor
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Pinyuan Tian
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Nicola Wanner
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fabian Braun
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Linus Butt
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK; Department of Paediatric Nephrology, Royal Manchester Children's Hospital, Manchester University Hospitals National Health Service (NHS) Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
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7
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Vartak T, Godson C, Brennan E. Therapeutic potential of pro-resolving mediators in diabetic kidney disease. Adv Drug Deliv Rev 2021; 178:113965. [PMID: 34508793 DOI: 10.1016/j.addr.2021.113965] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 07/26/2021] [Accepted: 09/05/2021] [Indexed: 02/06/2023]
Abstract
Renal microvascular disease associated with diabetes [Diabetic kidney disease - DKD] is the leading cause of chronic kidney disease. In DKD, glomerular basement membrane thickening, mesangial expansion, endothelial dysfunction, podocyte cell loss and renal tubule injury contribute to progressive glomerulosclerosis and tubulointerstitial fibrosis. Chronic inflammation is recognized as a major pathogenic mechanism for DKD, with resident and circulating immune cells interacting with local kidney cell populations to provoke an inflammatory response. The onset of inflammation is driven by the release of well described proinflammatory mediators, and this is typically followed by a resolution phase. Inflammation resolution is achieved through the bioactions of endogenous specialized pro-resolving lipid mediators (SPMs). As our understanding of SPMs advances 'resolution pharmacology' based approaches using these molecules are being explored in DKD.
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Affiliation(s)
- Tanwi Vartak
- Diabetes Complications Research Centre, Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
| | - Catherine Godson
- Diabetes Complications Research Centre, Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
| | - Eoin Brennan
- Diabetes Complications Research Centre, Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland.
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8
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Rogacka D. Insulin resistance in glomerular podocytes: Potential mechanisms of induction. Arch Biochem Biophys 2021; 710:109005. [PMID: 34371008 DOI: 10.1016/j.abb.2021.109005] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/19/2021] [Accepted: 08/05/2021] [Indexed: 01/15/2023]
Abstract
Glomerular podocytes are a target for the actions of insulin. Accumulating evidence indicates that exposure to nutrient overload induces insulin resistance in these cells, manifested by abolition of the stimulatory effect of insulin on glucose uptake. Numerous recent studies have investigated potential mechanisms of the induction of insulin resistance in podocytes. High glucose concentrations stimulated reactive oxygen species production through NADPH oxidase activation, decreased adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, and reduced deacetylase sirtuin 1 (SIRT1) protein levels and activity. Calcium signaling involving transient receptor potential cation channel C, member 6 (TRPC6) also was demonstrated to play an essential role in the regulation of insulin-dependent signaling and glucose uptake in podocytes. Furthermore, podocytes exposed to diabetic environment, with elevated insulin levels become insulin resistant as a result of degradation of insulin receptor (IR), resulting in attenuation of insulin signaling responsiveness. Also elevated levels of palmitic acid appear to be an important factor and contributor to podocytes insulin resistance. This review summarizes cellular and molecular alterations that contribute to the development of insulin resistance in glomerular podocytes.
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Affiliation(s)
- Dorota Rogacka
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Wita Stwosza 63, 80-308, Gdansk, Poland; University of Gdansk, Faculty of Chemistry, Department of Molecular Biotechnology, Wita Stwosza 63, 80-308, Gdansk, Poland.
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9
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Rogacka D, Piwkowska A. Beneficial effects of metformin on glomerular podocytes in diabetes. Biochem Pharmacol 2021; 192:114687. [PMID: 34274355 DOI: 10.1016/j.bcp.2021.114687] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 01/15/2023]
Abstract
Podocytes and their foot processes form an important cellular layer of the glomerular barrier involved in regulating glomerular permeability. Disturbances in podocyte function play a central role in the development of proteinuria in diabetic nephropathy. The retraction of podocyte foot processes forming a slit diaphragm is a common feature of proteinuria. Metformin is an oral antidiabetic agent of the biguanide class that is widely recommended for the treatment of high blood glucose in patients with type 2 diabetes mellitus. In addition to lowering glucose, several recent studies have reported potential beneficial effects of metformin on diabetic kidney function. Furthermore, a key molecule of the antidiabetic mechanism of action of metformin is adenosine 5'-monophospate-activated protein kinase (AMPK), as the metformin-induced activation of AMPK is well documented. The present review summarizes current knowledge on the protective effects of metformin against pathological changes in podocytes that are induced by hyperglycemia.
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Affiliation(s)
- Dorota Rogacka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute Polish Academy of Sciences, Wita Stwosza 63, Gdansk 80-308, Poland; Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk 80-308, Poland
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute Polish Academy of Sciences, Wita Stwosza 63, Gdansk 80-308, Poland; Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, Gdansk 80-308, Poland.
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10
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Audzeyenka I, Rogacka D, Rachubik P, Typiak M, Rychłowski M, Angielski S, Piwkowska A. The PKGIα-Rac1 pathway is a novel regulator of insulin-dependent glucose uptake in cultured rat podocytes. J Cell Physiol 2021; 236:4655-4668. [PMID: 33244808 DOI: 10.1002/jcp.30188] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 11/09/2022]
Abstract
Insulin plays a major role in regulating glucose homeostasis in podocytes. Protein kinase G type Iα (PKGIα) plays an important role in regulating glucose uptake in these cells. Rac1 signaling plays an essential role in the reorganization of the actin cytoskeleton and is also essential for insulin-stimulated glucose transport. The experiments were conducted using primary rat podocytes. We performed western blot analysis, evaluated small GTPases activity assays, measured radioactive glucose uptake, and performed immunofluorescence imaging to analyze the role of PKGIα-Rac1 signaling in regulating podocyte function. We also utilized a small-interfering RNA-mediated approach to determine the role of PKGIα and Rac1 in regulating glucose uptake in podocytes. The present study investigated the influence of the PKGI pathway on the insulin-dependent regulation of activity and cellular localization of small guanosine triphosphatases in podocytes. We found that the PKGIα-dependent activation of Rac1 signaling induced activation of the PAK/cofilin pathway and increased insulin-mediated glucose uptake in podocytes. The downregulation of PKGIα or Rac1 expression abolished this effect. Rac1 silencing prevented actin remodeling and GLUT4 translocation close to the cell membrane. These data provide evidence that PKGIα-dependent activation of the Rac1 signaling pathways is a novel regulator of insulin-mediated glucose uptake in cultured rat podocytes.
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Affiliation(s)
- Irena Audzeyenka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdańsk, Gdańsk, Poland
| | - Dorota Rogacka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdańsk, Gdańsk, Poland
| | - Patrycja Rachubik
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
| | - Marlena Typiak
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
| | - Michał Rychłowski
- Laboratory of Virus Molecular Biology, University of Gdańsk, Intercollegiate Faculty of Biotechnology, Medical University of Gdańsk, , Gdańsk, Poland
| | - Stefan Angielski
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdańsk, Gdańsk, Poland
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11
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Casagrande V, Iuliani G, Menini S, Pugliese G, Federici M, Menghini R. Restoration of renal TIMP3 levels via genetics and pharmacological approach prevents experimental diabetic nephropathy. Clin Transl Med 2021; 11:e305. [PMID: 33634991 PMCID: PMC7862169 DOI: 10.1002/ctm2.305] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/13/2021] [Accepted: 01/18/2021] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Diabetic nephropathy (DN), one of the major complications of diabetes, is characterized by albuminuria, glomerulosclerosis, and progressive loss of renal function. Loss of TIMP3, an Extracellular Matrix bound protein affecting both inflammation and fibrosis, is a hallmark of DN in human subjects and mouse models. METHODS This study was designed to provide evidences that the modulation of the system involving TIMP3 and its target A Disintegrin And Metalloproteinase 17 (ADAM17), may rescue kidney pathology in diabetic mice. Mice with cell-targeted overexpression of TIMP3 in myeloid cells (MacT3), podocyte-specific ADAM17 knockout mice (∆PodA17), and DBA/2J mice, were rendered diabetic at 8 weeks of age with a low-dose streptozotocin protocol. DBA/2J mice were administered new peptides based on the human TIMP3 N-terminal domain, specifically conjugated with G3C12, a carrier peptide highly selective and efficient for transport to the kidney. Twelve weeks after Streptozotocin injections, 24-hour albuminuria was determined by ELISA, kidney morphometry was analyzed by periodic acid-shift staining, and Real Time-PCR and western blot analysis were performed on mRNA and protein extracted from kidney cortex. RESULTS Our results showed that both genetic modifications and peptides treatment positively affect renal function and structure in diabetic mice, as indicated by a significant and consistent decline in albuminuria along with reduction in glomerular lesions, as indicated by reduced mesangial expansion and glomerular hypertrophy, decreased deposition of extracellular matrix in the mesangium, diminished protein expression of the NADPH oxidases 4 (NOX4), and the improvement of podocyte structural markers such as WT1, nephrin, and podocin. Moreover, the positive effects were exerted through a mechanism independent from glycemic control. CONCLUSIONS In diabetic mice the targeting of TIMP3 system improved kidney structure and function, representing a valid approach to develop new avenues to treat this severe complication of diabetes.
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Affiliation(s)
- Viviana Casagrande
- Departments of Systems MedicineUniversity of Rome “Tor Vergata”RomeItaly
- Research Unit of Diabetes and Endocrine DiseasesFondazione IRCCS “Casa Sollievo della Sofferenza”San Giovanni RotondoItaly
| | - Giulia Iuliani
- Departments of Systems MedicineUniversity of Rome “Tor Vergata”RomeItaly
| | - Stefano Menini
- Department of Clinical and Molecular Medicine“Sapienza” UniversityRomeItaly
| | - Giuseppe Pugliese
- Department of Clinical and Molecular Medicine“Sapienza” UniversityRomeItaly
| | - Massimo Federici
- Departments of Systems MedicineUniversity of Rome “Tor Vergata”RomeItaly
- Center for AtherosclerosisDepartment of Medical Sciences Policlinico Tor Vergata UniversityRomeItaly
| | - Rossella Menghini
- Departments of Systems MedicineUniversity of Rome “Tor Vergata”RomeItaly
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12
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Brennan E, Kantharidis P, Cooper ME, Godson C. Pro-resolving lipid mediators: regulators of inflammation, metabolism and kidney function. Nat Rev Nephrol 2021; 17:725-739. [PMID: 34282342 PMCID: PMC8287849 DOI: 10.1038/s41581-021-00454-y] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2021] [Indexed: 02/06/2023]
Abstract
Obesity, diabetes mellitus, hypertension and cardiovascular disease are risk factors for chronic kidney disease (CKD) and kidney failure. Chronic, low-grade inflammation is recognized as a major pathogenic mechanism that underlies the association between CKD and obesity, impaired glucose tolerance, insulin resistance and diabetes, through interaction between resident and/or circulating immune cells with parenchymal cells. Thus, considerable interest exists in approaches that target inflammation as a strategy to manage CKD. The initial phase of the inflammatory response to injury or metabolic dysfunction reflects the release of pro-inflammatory mediators including peptides, lipids and cytokines, and the recruitment of leukocytes. In self-limiting inflammation, the evolving inflammatory response is coupled to distinct processes that promote the resolution of inflammation and restore homeostasis. The discovery of endogenously generated lipid mediators - specialized pro-resolving lipid mediators and branched fatty acid esters of hydroxy fatty acids - which promote the resolution of inflammation and attenuate the microvascular and macrovascular complications of obesity and diabetes mellitus highlights novel opportunities for potential therapeutic intervention through the targeting of pro-resolution, rather than anti-inflammatory pathways.
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Affiliation(s)
- Eoin Brennan
- grid.7886.10000 0001 0768 2743Diabetes Complications Research Centre, Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
| | - Phillip Kantharidis
- grid.1002.30000 0004 1936 7857Department of Diabetes, Central Clinical School, Monash University, Melbourne, Victoria Australia
| | - Mark E. Cooper
- grid.1002.30000 0004 1936 7857Department of Diabetes, Central Clinical School, Monash University, Melbourne, Victoria Australia
| | - Catherine Godson
- grid.7886.10000 0001 0768 2743Diabetes Complications Research Centre, Conway Institute and School of Medicine, University College Dublin, Dublin, Ireland
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13
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Gil CL, Hooker E, Larrivée B. Diabetic Kidney Disease, Endothelial Damage, and Podocyte-Endothelial Crosstalk. Kidney Med 2021; 3:105-115. [PMID: 33604542 PMCID: PMC7873832 DOI: 10.1016/j.xkme.2020.10.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Diabetes-related complications are a significant source of morbidity and mortality worldwide. Diabetic kidney disease is a frequent microvascular complication and a primary cause of kidney failure in patients with diabetes. The glomerular filtration barrier is composed of 3 layers: the endothelium, glomerular basement membrane, and podocytes. Podocytes and the endothelium communicate through molecular crosstalk to maintain filtration at the glomerular filtration barrier. Chronic hyperglycemia affects all 3 layers of the glomerular filtration barrier, as well as the molecular crosstalk that occurs between the 2 cellular layers. One of the earliest events following chronic hyperglycemia is endothelial cell dysfunction. Early endothelial damage is associated with progression of diabetic kidney disease. However, current therapies are based in controlling glycemia and arterial blood pressure without targeting endothelial dysfunction. Disruption of the endothelial cell layer also alters the molecular crosstalk that occurs between the endothelium and podocytes. This review discusses both the physiologic and pathologic communication that occurs at the glomerular filtration barrier. It examines how these signaling components contribute to podocyte foot effacement, podocyte detachment, and the progression of diabetic kidney disease.
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Affiliation(s)
- Cindy Lora Gil
- Department of Biomedical Sciences, University of Montreal, Montréal, QC, Canada
- Maisonneuve-Rosemont Hospital Research Centre, University of Montreal, Montréal, QC, Canada
| | - Erika Hooker
- Maisonneuve-Rosemont Hospital Research Centre, University of Montreal, Montréal, QC, Canada
| | - Bruno Larrivée
- Department of Ophtalmology, University of Montreal, Montréal, QC, Canada
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14
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Pina AF, Borges DO, Meneses MJ, Branco P, Birne R, Vilasi A, Macedo MP. Insulin: Trigger and Target of Renal Functions. Front Cell Dev Biol 2020; 8:519. [PMID: 32850773 PMCID: PMC7403206 DOI: 10.3389/fcell.2020.00519] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 06/02/2020] [Indexed: 12/16/2022] Open
Abstract
Kidney function in metabolism is often underestimated. Although the word “clearance” is associated to “degradation”, at nephron level, proper balance between what is truly degraded and what is redirected to de novo utilization is crucial for the maintenance of electrolytic and acid–basic balance and energy conservation. Insulin is probably one of the best examples of how diverse and heterogeneous kidney response can be. Kidney has a primary role in the degradation of insulin released in the bloodstream, but it is also incredibly susceptible to insulin action throughout the nephron. Fluctuations in insulin levels during fast and fed state add another layer of complexity in the understanding of kidney fine-tuning. This review aims at revisiting renal insulin actions and clearance and to address the association of kidney dysmetabolism with hyperinsulinemia and insulin resistance, both highly prevalent phenomena in modern society.
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Affiliation(s)
- Ana F Pina
- Centro de Estudos de Doenças Crónicas, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal.,ProRegeM Ph.D. Programme, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal.,Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Diego O Borges
- Centro de Estudos de Doenças Crónicas, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal.,Molecular Biosciences Ph.D. Programme, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Maria João Meneses
- Centro de Estudos de Doenças Crónicas, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal.,ProRegeM Ph.D. Programme, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Patrícia Branco
- Department of Nephrology, Centro Hospitalar Lisboa Ocidental, Lisbon, Portugal.,Portuguese Diabetes Association - Education and Research Center (APDP-ERC), Lisbon, Portugal
| | - Rita Birne
- Department of Nephrology, Centro Hospitalar Lisboa Ocidental, Lisbon, Portugal.,Portuguese Diabetes Association - Education and Research Center (APDP-ERC), Lisbon, Portugal
| | - Antonio Vilasi
- Institute of Clinical Physiology - National Research Council, Reggio Calabria Unit1, Reggio Calabria, Italy
| | - Maria Paula Macedo
- Centro de Estudos de Doenças Crónicas, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal.,Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.,Portuguese Diabetes Association - Education and Research Center (APDP-ERC), Lisbon, Portugal
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15
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Hosawi SB, Humphries JD, Coward RJ, Knight D, Humphries MJ, Lennon R. Global proteomic analysis of insulin receptor interactors in glomerular podocytes. Wellcome Open Res 2020; 5:202. [PMID: 33458251 PMCID: PMC7788524 DOI: 10.12688/wellcomeopenres.16072.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2020] [Indexed: 12/16/2022] Open
Abstract
Background: Insulin signalling contributes to diverse cellular activities including protein synthesis, proliferation and cell survival. Insulin resistance describes the inability of cells to activate the insulin signalling pathway effectively; leading to pathological effects in multiple organ systems including the kidney. In diabetic kidney disease, there is progressive glomerular dysfunction and recent studies have demonstrated that the kidney podocyte is a direct target for insulin action. In this study we defined the literature-based insulin receptor (INSR) interactome and utilised an unbiased proteomic approach to examine INSR interactors in podocytes. Methods: Human podocytes expressing the INSR were characterised under basal and insulin resistant conditions. The INSR was isolated by whole cell immunoprecipitation following a time course stimulation of 2, 7, and 15 minutes with of 100nM insulin. The resulting INSR complexes were analysed by label-free mass spectrometry (MS) to detect protein interactors. Results: We identified 27 known, direct INSR interactors in addition to novel interactors including doublecortin domain-containing protein 2 (DCDC2). The interaction of DCDC2 with the INSR was confirmed by immunoprecipitation and immunofluorescence, and under insulin resistant conditions, DCDC2 had increased association with the INSR. siRNA knockdown of DCDC2 in podocytes resulted in cell morphological change and altered INSR localisation. Conclusion: This study provides insight into the complexity of INSR interactors in podocytes and highlights DCDC2 as a novel INSR binding protein. Involvement of this novel interactor in insulin signalling and podocyte biology may explain how insulin resistance alters morphology and integrity of the glomerular filtration barrier.
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Affiliation(s)
- Salman B. Hosawi
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester, M13 9PT, UK
- Department of Biochemistry, King AbdulAziz University, Jeddah, Saudi Arabia
| | - Jonathan D. Humphries
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester, M13 9PT, UK
| | | | - David Knight
- Biomolecular Analysis Core Facility, University of Manchester, Manchester, M13 9PT, UK
| | - Martin J. Humphries
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester, M13 9PT, UK
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester, M13 9PT, UK
- Department of Paediatric Nephrology, Royal Manchester Children’s Hospital, Manchester, UK
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16
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Audzeyenka I, Rachubik P, Rogacka D, Typiak M, Kulesza T, Angielski S, Rychłowski M, Wysocka M, Gruba N, Lesner A, Saleem MA, Piwkowska A. Cathepsin C is a novel mediator of podocyte and renal injury induced by hyperglycemia. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118723. [PMID: 32302668 DOI: 10.1016/j.bbamcr.2020.118723] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/08/2020] [Accepted: 04/09/2020] [Indexed: 02/07/2023]
Abstract
A growing body of evidence suggests a role of proteolytic enzymes in the development of diabetic nephropathy. Cathepsin C (CatC) is a well-known regulator of inflammatory responses, but its involvement in podocyte and renal injury remains obscure. We used Zucker rats, a genetic model of metabolic syndrome and insulin resistance, to determine the presence, quantity, and activity of CatC in the urine. In addition to the animal study, we used two cellular models, immortalized human podocytes and primary rat podocytes, to determine mRNA and protein expression levels via RT-PCR, Western blot, and confocal microscopy, and to evaluate CatC activity. The role of CatC was analyzed in CatC-depleted podocytes using siRNA and glycolytic flux parameters were obtained from extracellular acidification rate (ECAR) measurements. In functional analyses, podocyte and glomerular permeability to albumin was determined. We found that podocytes express and secrete CatC, and a hyperglycemic environment increases CatC levels and activity. Both high glucose and non-specific activator of CatC phorbol 12-myristate 13-acetate (PMA) diminished nephrin, cofilin, and GLUT4 levels and induced cytoskeletal rearrangements, increasing albumin permeability in podocytes. These negative effects were completely reversed in CatC-depleted podocytes. Moreover, PMA, but not high glucose, increased glycolytic flux in podocytes. Finally, we demonstrated that CatC expression and activity are increased in the urine of diabetic Zucker rats. We propose a novel mechanism of podocyte injury in diabetes, providing deeper insight into the role of CatC in podocyte biology.
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Affiliation(s)
- Irena Audzeyenka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdansk, Poland; Faculty of Chemistry, University of Gdansk, Poland.
| | - Patrycja Rachubik
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdansk, Poland
| | - Dorota Rogacka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdansk, Poland; Faculty of Chemistry, University of Gdansk, Poland
| | - Marlena Typiak
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdansk, Poland
| | - Tomasz Kulesza
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdansk, Poland
| | - Stefan Angielski
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdansk, Poland
| | - Michał Rychłowski
- Intercollegiate Faculty of Biotechnology, University of Gdansk - Medical University of Gdansk, Poland
| | | | | | - Adam Lesner
- Faculty of Chemistry, University of Gdansk, Poland
| | - Moin A Saleem
- Bristol Renal, University of Bristol, United Kingdom
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdansk, Poland; Faculty of Chemistry, University of Gdansk, Poland
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17
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Kravets I, Mallipattu SK. The Role of Podocytes and Podocyte-Associated Biomarkers in Diagnosis and Treatment of Diabetic Kidney Disease. J Endocr Soc 2020; 4:bvaa029. [PMID: 32232184 PMCID: PMC7093089 DOI: 10.1210/jendso/bvaa029] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 02/27/2020] [Indexed: 12/23/2022] Open
Abstract
Diabetic kidney disease (DKD) is an important public health problem. Podocyte injury is a central event in the mechanism of DKD development. Podocytes are terminally differentiated, highly specialized glomerular visceral epithelial cells critical for the maintenance of the glomerular filtration barrier. Although potential mechanisms by which diabetic milieu contributes to irreversible loss of podocytes have been described, identification of markers that prognosticate either the development of DKD or the progression to end-stage kidney disease (ESKD) have only recently made it to the forefront. Currently, the most common marker of early DKD is microalbuminuria; however, this marker has significant limitations: not all diabetic patients with microalbuminuria will progress to ESKD and as many as 30% of patients with DKD have normal urine albumin levels. Several novel biomarkers indicating glomerular or tubular damage precede microalbuminuria, suggesting that the latter develops when significant kidney injury has already occurred. Because podocyte injury plays a key role in DKD pathogenesis, identification of markers of early podocyte injury or loss may play an important role in the early diagnosis of DKD. Such biomarkers in the urine include podocyte-released microparticles as well as expression of podocyte-specific markers. Here, we review the mechanisms by which podocyte injury contributes to DKD as well as key markers that have been recently implicated in the development and/or progression of DKD and might serve to identify individuals that require earlier preventative care and treatment in order to slow the progression to ESKD.
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Affiliation(s)
- Igor Kravets
- Division of Endocrinology, Department of Medicine, Stony Brook University, Stony Brook, NY
| | - Sandeep K Mallipattu
- Division of Nephrology, Department of Medicine, Stony Brook University, Stony Brook, NY
- Renal Section, Northport VA Medical Center, Northport, NY
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18
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Metformin reduces TRPC6 expression through AMPK activation and modulates cytoskeleton dynamics in podocytes under diabetic conditions. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165610. [DOI: 10.1016/j.bbadis.2019.165610] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 11/05/2019] [Accepted: 11/06/2019] [Indexed: 11/20/2022]
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19
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Yang S, Ma C, Wu H, Zhang H, Yuan F, Yang G, Yang Q, Jia L, Liang Z, Kang L. Tectorigenin attenuates diabetic nephropathy by improving vascular endothelium dysfunction through activating AdipoR1/2 pathway. Pharmacol Res 2020; 153:104678. [PMID: 32014572 DOI: 10.1016/j.phrs.2020.104678] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 01/17/2020] [Accepted: 01/30/2020] [Indexed: 01/10/2023]
Abstract
Diabetic nephropathy (DN), a kind of microvascular complication, is a primary cause of end-stage renal disease worldwide. However, therapeutic drugs for DN treatment are still in lack. The glomerular endothelium is essential to maintain selective permeability of glomerular filtration barrier and glomerular vasculature function. Growing evidences show that endothelial dysfunction or injury is the initial stage of vascular damage in DN, which can be induced by hyperglycemia, lipotoxicity, and inflammation. Therefore, to improve the function of vascular endothelium in kidney is a key point for treatment of DN. As a plant isoflavone, tectorigenin (TEC) has attracted considerable attention due to its anti-proliferative and anti-inflammatory functions. However, whether TEC could inhibit the DN development remains unknown. In this study, we examined the effects of TEC on DN development in db/db mice, a type of genetic defect diabetic mice that can spontaneously develop into severe renal dysfunction. Intriguingly, TEC treatment restored diabetes-induced glucose and lipid metabolic disorder; and improved the deterioration of renal function, particularly the renal endothelium function in db/db mice. Additionally, TEC inhibited the renal inflammation via reducing macrophages infiltration and M1 polarization. Moreover, TEC inhibited lipopolysaccharide (LPS)-induced endothelial injury and M1 polarization in vitro. Mechanistically, TEC partially restored the reduction in expression of adiponectin receptor 1/2 (AdipoR1/2), pi-LKB1, pi-AMPKα, and PPARα in vitro and in vivo. Noteworthy, these beneficial pharmacological activities mediated by TEC were significantly attenuated after AdipoR1/2 knockdown by siRNA, indicating that AdipoR1/2 plays a critical role in protection against DN. Collectively, these results suggested that TEC have a potently effect for retarding type 2 diabetes-associated DN.
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Affiliation(s)
- Shu Yang
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China
| | - Chuanrui Ma
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China; Tianjin Key Laboratory of Translational Research of TCM Prescription and Syndrome, Tianjin, China
| | - Han Wu
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China; Department of Endocrinology, Key Laboratory of Endocrinology, National Health Commission, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Hao Zhang
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China; Tianjin Key Laboratory of Translational Research of TCM Prescription and Syndrome, Tianjin, China
| | - Fengyi Yuan
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China
| | - Guangyan Yang
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China
| | - Qi Yang
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China
| | - Lijing Jia
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China.
| | - Zhen Liang
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China.
| | - Lin Kang
- Department of Endocrinology, The 2nd Clinical Medical College of Jinan University, Shenzhen People's Hospital, Shenzhen, China.
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20
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VEGFR2 Blockade Improves Renal Damage in an Experimental Model of Type 2 Diabetic Nephropathy. J Clin Med 2020; 9:jcm9020302. [PMID: 31973092 PMCID: PMC7074274 DOI: 10.3390/jcm9020302] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 01/14/2020] [Accepted: 01/16/2020] [Indexed: 12/29/2022] Open
Abstract
The absence of optimal treatments for Diabetic Nephropathy (DN) highlights the importance of the search for novel therapeutic targets. The vascular endothelial growth factor receptor 2 (VEGFR2) pathway is activated in experimental and human DN, but the effects of its blockade in experimental models of DN is still controversial. Here, we test the effects of a therapeutic anti-VEGFR2 treatment, using a VEGFR2 kinase inhibitor, on the progression of renal damage in the BTBR ob/ob (leptin deficiency mutation) mice. This experimental diabetic model develops histological characteristics mimicking the key features of advanced human DN. A VEGFR2 pathway-activation blockade using the VEGFR2 kinase inhibitor SU5416, starting after kidney disease development, improves renal function, glomerular damage (mesangial matrix expansion and basement membrane thickening), tubulointerstitial inflammation and tubular atrophy, compared to untreated diabetic mice. The downstream mechanisms involved in these beneficial effects of VEGFR2 blockade include gene expression restoration of podocyte markers and downregulation of renal injury biomarkers and pro-inflammatory mediators. Several ligands can activate VEGFR2, including the canonical ligands VEGFs and GREMLIN. Activation of a GREMLIN/VEGFR2 pathway, but not other ligands, is correlated with renal damage progression in BTBR ob/ob diabetic mice. RNA sequencing analysis of GREMLIN-regulated genes confirm the modulation of proinflammatory genes and related-molecular pathways. Overall, these data show that a GREMLIN/VEGFR2 pathway activation is involved in diabetic kidney disease and could potentially be a novel therapeutic target in this clinical condition.
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21
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Lehtonen S. SHIPping out diabetes-Metformin, an old friend among new SHIP2 inhibitors. Acta Physiol (Oxf) 2020; 228:e13349. [PMID: 31342643 PMCID: PMC6916339 DOI: 10.1111/apha.13349] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/15/2019] [Accepted: 07/19/2019] [Indexed: 02/06/2023]
Abstract
SHIP2 (Src homology 2 domain‐containing inositol 5′‐phosphatase 2) belongs to the family of 5′‐phosphatases. It regulates the phosphoinositide 3‐kinase (PI3K)‐mediated insulin signalling cascade by dephosphorylating the 5′‐position of PtdIns(3,4,5)P3 to generate PtdIns(3,4)P2, suppressing the activity of the pathway. SHIP2 mouse models and genetic studies in human propose that increased expression or activity of SHIP2 contributes to the pathogenesis of the metabolic syndrome, hypertension and type 2 diabetes. This has raised great interest to identify SHIP2 inhibitors that could be used to design new treatments for metabolic diseases. This review summarizes the central mechanisms associated with the development of diabetic kidney disease, including the role of insulin resistance, and then moves on to describe the function of SHIP2 as a regulator of metabolism in mouse models. Finally, the identification of SHIP2 inhibitors and their effects on metabolic processes in vitro and in vivo are outlined. One of the newly identified SHIP2 inhibitors is metformin, the first‐line medication prescribed to patients with type 2 diabetes, further boosting the attraction of SHIP2 as a treatment target to ameliorate metabolic disorders.
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Affiliation(s)
- Sanna Lehtonen
- Department of Pathology and Research Program for Clinical and Molecular Metabolism, Faculty of Medicine University of Helsinki Helsinki Finland
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22
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Abstract
Finding new therapeutic targets of glomerulosclerosis treatment is an ongoing quest. Due to a living environment of various stresses and pathological stimuli, podocytes are prone to injuries; moreover, as a cell without proliferative potential, loss of podocytes is vital in the pathogenesis of glomerulosclerosis. Thus, sufficient understanding of factors and underlying mechanisms of podocyte injury facilitates the advancement of treating and prevention of glomerulosclerosis. The clinical symptom of podocyte injury is proteinuria, sometimes with loss of kidney functions progressing to glomerulosclerosis. Injury-induced changes in podocyte physiology and function are actually not a simple passive process, but a complex interaction of proteins that comprise the anatomical structure of podocytes at molecular levels. This chapter lists several aspects of podocyte injuries along with potential mechanisms, including glucose and lipid metabolism disorder, hypertension, RAS activation, micro-inflammation, immune disorder, and other factors. These aspects are not technically separated items, but intertwined with each other in the pathogenesis of podocyte injuries.
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23
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Yoon JJ, Park JH, Kim HJ, Jin HG, Kim HY, Ahn YM, Kim YC, Lee HS, Lee YJ, Kang DG. Dianthus superbus Improves Glomerular Fibrosis and Renal Dysfunction in Diabetic Nephropathy Model. Nutrients 2019; 11:E553. [PMID: 30841605 PMCID: PMC6471502 DOI: 10.3390/nu11030553] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/22/2019] [Accepted: 02/28/2019] [Indexed: 01/19/2023] Open
Abstract
Glomerular fibrosis is caused by an accumulation of intercellular spaces containing mesangial matrix proteins through either diffused or nodular changes. Dianthus superbus has been used in traditional medicine as a diuretic, a contraceptive, and an anti-inflammatory agent. The aim of this study was to investigate the effects of Dianthus superbus-EtOAc soluble fraction (DS-EA) on glomerular fibrosis and renal dysfunction, which has been implicated in diabetic nephropathy in human renal mesangial cells and db/db mice. DS-EA was administered to db/db mice at 10 or 50 mg/kg/day for 8 weeks. DS-EA treatment significantly ameliorated blood glucose, insulin, the homeostasis model assessment of insulin resistance (HOMA-IR) index, and HbA1c in diabetic mice. DS-EA decreased albumin excretion, creatinine clearance (Ccr), and plasma creatinine levels. DS-EA also ameliorated the levels of kidney injury molecules-1 (KIM-1) and C-reactive protein. DS-EA reduced the periodic acid-Schiff (PAS) staining intensity and basement membrane thickening in glomeruli of the diabetic nephropathy model. In addition, DS-EA suppressed transforming growth factor-β (TGF-β)/Smad signaling. Collagen type IV, a glomerular fibrosis biomarker, was significantly decreased upon DS-EA administration. DS-EA pretreatment attenuated levels of inflammation factors such as intracellular cell adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein-1 (MCP-1). DS-EA inhibited the translocation of nuclear factor kappa B (NF-κB) in Angiotensin II (Ang II)-stimulated mesangial cells. These findings suggest that DS-EA has a protective effect against renal inflammation and fibrosis. Therefore, DS-EA may serve as a potential therapeutic agent targeting glomerulonephritis and glomerulosclerosis, which lead to diabetic nephropathy.
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Affiliation(s)
- Jung Joo Yoon
- Hanbang Cardio-Renal Syndrome Research Center, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
| | - Ji Hun Park
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
| | - Hye Jin Kim
- College of Pharmacy, Wonkwang University, Iksan 54538, Korea.
| | - Hong-Guang Jin
- College of Pharmacy, Wonkwang University, Iksan 54538, Korea.
- School of Pharmacy and Life Sciences, Jiujiang University, Jiujiang 332005, China.
| | - Hye Yoom Kim
- Hanbang Cardio-Renal Syndrome Research Center, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
| | - You Mee Ahn
- Hanbang Cardio-Renal Syndrome Research Center, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
| | - Youn Chul Kim
- College of Pharmacy, Wonkwang University, Iksan 54538, Korea.
| | - Ho Sub Lee
- Hanbang Cardio-Renal Syndrome Research Center, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
| | - Yun Jung Lee
- Hanbang Cardio-Renal Syndrome Research Center, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
| | - Dae Gill Kang
- Hanbang Cardio-Renal Syndrome Research Center, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
- College of Oriental Medicine and Professional Graduate School of Oriental Medicine, Wonkwang University, 460, Iksan-daero, Iksan, Jeonbuk 54538, Korea.
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24
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Wasik AA, Dash SN, Lehtonen S. Septins in kidney: A territory little explored. Cytoskeleton (Hoboken) 2018; 76:154-162. [PMID: 30004646 PMCID: PMC6585700 DOI: 10.1002/cm.21477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/15/2018] [Accepted: 07/03/2018] [Indexed: 12/15/2022]
Abstract
Septins are a conserved family of GTP‐binding proteins that assemble into cytoskeletal filaments to function in a highly sophisticated and physiologically regulated manner. Originally septins were discovered in the budding yeast as membrane‐associated filaments that affect cell polarity and cytokinesis. In the last decades, much progress has been made in understanding the biochemical properties and cell biological functions of septins. In line with this, mammalian septins have been shown to be involved in various cellular processes, including regulation of cell polarity, cytoskeletal organization, vesicle trafficking, ciliogenesis, and cell–pathogen interactions. A growing number of studies have shown that septins play important roles in tissue and organ development and physiology; yet, little is known about their role in the kidney. In the following review, we discuss the structure and functions of septins in general and summarize the evidence for their presence and roles in the kidney.
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Affiliation(s)
- Anita A Wasik
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Surjya N Dash
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, Helsinki, Finland
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NaoXinTong Capsules inhibit the development of diabetic nephropathy in db/db mice. Sci Rep 2018; 8:9158. [PMID: 29904053 PMCID: PMC6002396 DOI: 10.1038/s41598-018-26746-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 05/04/2018] [Indexed: 12/17/2022] Open
Abstract
NaoXinTong Capsule (NXT), a Chinese medicine, is currently used to treat patients with cardiovascular and cerebrovascular diseases. Clinical observations indicate its anti-diabetic functions with unclear mechanisms. Herein, we report the effect of NXT on diabetic nephropathy (DN). Type 2 diabetic db/db mice were treated with NXT for 14 weeks. In the course of treatment, NXT reduced diabetes-increased glucose levels and improved renal functions. At the end of treatment, we found that NXT ameliorated serum lipid profiles and other biochemical parameters. In the kidney, NXT inhibited mesangial matrix expansion, expression of vascular endothelial growth factor A, fibronectin, advanced glycation end product and its receptor. Meanwhile, it reduced the diabetes-induced podocyte injury by increasing WT1 and nephrin expression. In addition, NXT inhibited accumulation of extracellular matrix proteins by increasing MMP2/9 expression through inactivation of TGFβ/Smad pathway and CTGF expression. Mechanically, NXT activated insulin signaling pathway by increasing expression of INSR, IRS and FGF21, phosphorylation of Akt and AMPKα in the liver, INSR phosphorylation in the kidney, and FGF21 and GLUT4 expression in adipose tissue and skeletal muscle. Taken together, our study demonstrates that NXT inhibits DN by ameliorating glucose/lipid metabolism, maintaining tissue structure integrity, and correcting diabetes-induced renal dysfunctions.
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Yu SMW, Bonventre JV. Acute Kidney Injury and Progression of Diabetic Kidney Disease. Adv Chronic Kidney Dis 2018; 25:166-180. [PMID: 29580581 DOI: 10.1053/j.ackd.2017.12.005] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 12/15/2017] [Accepted: 12/22/2017] [Indexed: 12/23/2022]
Abstract
Diabetic kidney disease, commonly termed diabetic nephropathy (DN), is the most common cause of end-stage kidney disease (ESKD) worldwide. The characteristic histopathology of DN includes glomerular basement membrane thickening, mesangial expansion, nodular glomerular sclerosis, and tubulointerstitial fibrosis. Diabetes is associated with a number of metabolic derangements, such as reactive oxygen species overproduction, hypoxic state, mitochondrial dysfunction, and inflammation. In the past few decades, our knowledge of DN has advanced considerably although much needs to be learned. The traditional paradigm of glomerulus-centered pathophysiology has expanded to the tubule-interstitium, the immune response and inflammation. Biomarkers of proximal tubule injury have been shown to correlate with DN progression, independent of traditional glomerular injury biomarkers such as albuminuria. In this review, we summarize mechanisms of increased susceptibility to acute kidney injury in diabetes mellitus and the roles played by many kidney cell types to facilitate maladaptive responses leading to chronic and end-stage kidney disease.
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Wasik AA, Lehtonen S. Glucose Transporters in Diabetic Kidney Disease-Friends or Foes? Front Endocrinol (Lausanne) 2018; 9:155. [PMID: 29686650 PMCID: PMC5900043 DOI: 10.3389/fendo.2018.00155] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/22/2018] [Indexed: 12/16/2022] Open
Abstract
Diabetic kidney disease (DKD) is a major microvascular complication of diabetes and a common cause of end-stage renal disease worldwide. DKD manifests as an increased urinary protein excretion (albuminuria). Multiple studies have shown that insulin resistance correlates with the development of albuminuria in non-diabetic and diabetic patients. There is also accumulating evidence that glomerular epithelial cells or podocytes are insulin sensitive and that insulin signaling in podocytes is essential for maintaining normal kidney function. At the cellular level, the mechanisms leading to the development of insulin resistance include mutations in the insulin receptor gene, impairments in the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway, or perturbations in the trafficking of glucose transporters (GLUTs), which mediate the uptake of glucose into cells. Podocytes express several GLUTs, including GLUT1, GLUT2, GLUT3, GLUT4, and GLUT8. Of these, the most studied ones are GLUT1 and GLUT4, both shown to be insulin responsive in podocytes. In the basal state, GLUT4 is preferentially located in perinuclear and cytosolic vesicular structures and to a lesser extent at the plasma membrane. After insulin stimulation, GLUT4 is sorted into GLUT4-containing vesicles (GCVs) that translocate to the plasma membrane. GCV trafficking consists of several steps, including approaching of the GCVs to the plasma membrane, tethering, and docking, after which the lipid bilayers of the GCVs and the plasma membrane fuse, delivering GLUT4 to the cell surface for glucose uptake into the cell. Studies have revealed novel molecular regulators of the GLUT trafficking in podocytes and unraveled unexpected roles for GLUT1 and GLUT4 in the development of DKD, summarized in this review. These findings pave the way for better understanding of the mechanistic pathways associated with the development and progression of DKD and aid in the development of new treatments for this devastating disease.
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Martin CE, Jones N. Nephrin Signaling in the Podocyte: An Updated View of Signal Regulation at the Slit Diaphragm and Beyond. Front Endocrinol (Lausanne) 2018; 9:302. [PMID: 29922234 PMCID: PMC5996060 DOI: 10.3389/fendo.2018.00302] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/22/2018] [Indexed: 12/11/2022] Open
Abstract
Podocytes are a major component of the glomerular blood filtration barrier, and alterations to the morphology of their unique actin-based foot processes (FP) are a common feature of kidney disease. Adjacent FP are connected by a specialized intercellular junction known as the slit diaphragm (SD), which serves as the ultimate barrier to regulate passage of macromolecules from the blood. While the link between SD dysfunction and reduced filtration selectivity has been recognized for nearly 50 years, our understanding of the underlying molecular circuitry began only 20 years ago, sparked by the identification of NPHS1, encoding the transmembrane protein nephrin. Nephrin not only functions as the core component of the extracellular SD filtration network but also as a signaling scaffold via interactions at its short intracellular region. Phospho-regulation of several conserved tyrosine residues in this region influences signal transduction pathways which control podocyte cell adhesion, shape, and survival, and emerging studies highlight roles for nephrin phospho-dynamics in mechanotransduction and endocytosis. The following review aims to summarize the last 5 years of advancement in our knowledge of how signaling centered at nephrin directs SD barrier formation and function. We further provide insight on promising frontiers in podocyte biology, which have implications for SD signaling in the healthy and diseased kidney.
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Lay AC, Coward RJM. The Evolving Importance of Insulin Signaling in Podocyte Health and Disease. Front Endocrinol (Lausanne) 2018; 9:693. [PMID: 30524379 PMCID: PMC6258712 DOI: 10.3389/fendo.2018.00693] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/05/2018] [Indexed: 12/17/2022] Open
Abstract
Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide, occuring in approximately one-third of diabetic patients. One of the earliest hallmarks of DKD is albuminuria, often occurring following disruptions to the glomerular filtration barrier. Podocytes are highly specialized cells with a central role in filtration barrier maintenance; hence, podocyte dysfunction is a major cause of albuminuria in many settings, including DKD. Numerous studies over the last decade have highlighted the importance of intact podocyte insulin responses in the maintenance of podocyte function. This review summarizes our current perspectives on podocyte insulin signaling, highlighting evidence to support the notion that dysregulated podocyte insulin responses contribute toward podocyte damage, particularly during the pathogenesis of DKD.
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Lay AC, Hurcombe JA, Betin VMS, Barrington F, Rollason R, Ni L, Gillam L, Pearson GME, Østergaard MV, Hamidi H, Lennon R, Welsh GI, Coward RJM. Prolonged exposure of mouse and human podocytes to insulin induces insulin resistance through lysosomal and proteasomal degradation of the insulin receptor. Diabetologia 2017; 60:2299-2311. [PMID: 28852804 PMCID: PMC6448913 DOI: 10.1007/s00125-017-4394-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/28/2017] [Indexed: 12/12/2022]
Abstract
AIMS/HYPOTHESIS Podocytes are insulin-responsive cells of the glomerular filtration barrier and are key in preventing albuminuria, a hallmark feature of diabetic nephropathy. While there is evidence that a loss of insulin signalling to podocytes is detrimental, the molecular mechanisms underpinning the development of podocyte insulin resistance in diabetes remain unclear. Thus, we aimed to further investigate podocyte insulin responses early in the context of diabetic nephropathy. METHODS Conditionally immortalised human and mouse podocyte cell lines and glomeruli isolated from db/db DBA/2J mice were studied. Podocyte insulin responses were investigated with western blotting, cellular glucose uptake assays and automated fluorescent imaging of the actin cytoskeleton. Quantitative (q)RT-PCR was employed to investigate changes in mRNA. Human cell lines stably overproducing the insulin receptor (IR) and nephrin were also generated, using lentiviral constructs. RESULTS Podocytes exposed to a diabetic environment (high glucose, high insulin and the proinflammatory cytokines TNF-α and IL-6) become insulin resistant with respect to glucose uptake and activation of phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signalling. These podocytes lose expression of the IR as a direct consequence of prolonged exposure to high insulin concentrations, which causes an increase in IR protein degradation via a proteasome-dependent and bafilomycin-sensitive pathway. Reintroducing the IR into insulin-resistant human podocytes rescues upstream phosphorylation events, but not glucose uptake. Stable expression of nephrin is also required for the insulin-stimulated glucose uptake response in podocytes and for efficient insulin-stimulated remodelling of the actin cytoskeleton. CONCLUSIONS/INTERPRETATION Together, these results suggest that IR degradation, caused by high levels of insulin, drives early podocyte insulin resistance, and that both the IR and nephrin are required for full insulin sensitivity of this cell. This could be highly relevant for the development of nephropathy in individuals with type 2 diabetes, who are commonly hyperinsulinaemic in the early phases of their disease.
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Affiliation(s)
- Abigail C Lay
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Jenny A Hurcombe
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Virginie M S Betin
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Fern Barrington
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Ruth Rollason
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Lan Ni
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Lawrence Gillam
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Grace M E Pearson
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Mette V Østergaard
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - Hellyeh Hamidi
- Wellcome Trust Centre for Cell-Matrix Research, Division of Cell Matrix Biology and Regenerative Medicine, School of Biology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Division of Cell Matrix Biology and Regenerative Medicine, School of Biology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Gavin I Welsh
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Richard J M Coward
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK.
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Matkar PN, Ariyagunarajah R, Leong-Poi H, Singh KK. Friends Turned Foes: Angiogenic Growth Factors beyond Angiogenesis. Biomolecules 2017; 7:biom7040074. [PMID: 28974056 PMCID: PMC5745456 DOI: 10.3390/biom7040074] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/15/2017] [Accepted: 09/22/2017] [Indexed: 12/13/2022] Open
Abstract
Angiogenesis, the formation of new blood vessels from pre-existing ones is a biological process that ensures an adequate blood flow is maintained to provide the cells with a sufficient supply of nutrients and oxygen within the body. Numerous soluble growth factors and inhibitors, cytokines, proteases as well as extracellular matrix proteins and adhesion molecules stringently regulate the multi-factorial process of angiogenesis. The properties and interactions of key angiogenic molecules such as vascular endothelial growth factors (VEGFs), fibroblast growth factors (FGFs) and angiopoietins have been investigated in great detail with respect to their molecular impact on angiogenesis. Since the discovery of angiogenic growth factors, much research has been focused on their biological actions and their potential use as therapeutic targets for angiogenic or anti-angiogenic strategies in a context-dependent manner depending on the pathologies. It is generally accepted that these factors play an indispensable role in angiogenesis. However, it is becoming increasingly evident that this is not their only role and it is likely that the angiogenic factors have important functions in a wider range of biological and pathological processes. The additional roles played by these molecules in numerous pathologies and biological processes beyond angiogenesis are discussed in this review.
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Affiliation(s)
- Pratiek N Matkar
- Division of Cardiology, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | | | - Howard Leong-Poi
- Division of Cardiology, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Krishna K Singh
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada.
- Division of Vascular Surgery, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada.
- Department of Surgery, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Miaomiao W, Chunhua L, Xiaochen Z, Xiaoniao C, Hongli L, Zhuo Y. Autophagy is involved in regulating VEGF during high-glucose-induced podocyte injury. MOLECULAR BIOSYSTEMS 2017; 12:2202-12. [PMID: 27138352 DOI: 10.1039/c6mb00195e] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Podocytes are the major sites of vascular endothelial growth factor (VEGF) production in kidneys. Over-expression of VEGF is involved in the pathogenesis of diabetic nephropathy (DN), and an emerging body of evidence suggests that autophagy plays an important role in DN. In this study, the effect of autophagy on over-expressed VEGF along with its underlying mechanism was investigated in streptozotocin (STZ)-induced diabetic mice and high glucose (HG)-induced podocytes. We found that diabetes caused podocyte foot process effacement and VEGF upregulation significantly. In vitro, high glucose induced VEGF and reduced the podocyte viability. After treatment with rapamycin in podocytes, an autophagy inducer, VEGF activation was significantly abrogated and podocyte injury was ameliorated. In contrast, podocytes treated with 3-methyladenine (3-MA), a potent autophagy inhibitor, had increased VEGF expression. Furthermore, 3-MA significantly increased the production of HG-induced reactive oxygen species (ROS), whereas rapamycin decreased the cellular ROS level. Inhibition of ROS production by N-acetyl-l-cysteine (NAC) effectively reduced the over-expression of VEGF. These studies show the vital role of autophagy in the regulation of VEGF, which presents a protective effect on HG-induced podocyte injury. ROS production may be an important mechanism for mediating this process.
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Affiliation(s)
- Wei Miaomiao
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, Tianjin 300071, China.
| | - Liu Chunhua
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, Tianjin 300071, China.
| | - Zhang Xiaochen
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, Tianjin 300071, China.
| | - Chen Xiaoniao
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, Tianjin 300071, China.
| | - Lin Hongli
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, China.
| | - Yang Zhuo
- College of Medicine, State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, Tianjin 300071, China.
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Mesenchymal Stem Cell-Based Therapies against Podocyte Damage in Diabetic Nephropathy. Tissue Eng Regen Med 2017; 14:201-210. [PMID: 30603477 DOI: 10.1007/s13770-017-0026-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/25/2016] [Accepted: 06/13/2016] [Indexed: 01/02/2023] Open
Abstract
Injury to podocytes is an early event in diabetic nephropathy leading to proteinuria with possible progression to end-stage renal failure. The podocytes are unique and highly specialized cells that cover the outer layer of kidney ultra-filtration barrier and play an important role in glomerular function. In the past few decades, adult stem cells, such as mesenchymal stem cells (MSCs) with a regenerative and differentiative capacity have been extensively used in cell-based therapies. In addition to their capability for regeneration and differentiation, MSCs contributes to their milieu by paracrine action of a series of growth factors via antiapoptotic, mitogenic and other cytokine actions that actively participate in treatment of podocyte damage through prevention of podocyte effacement, detachment and apoptosis. It is hoped that novel stem cell-based therapies will be developed in the future to prevent podocyte injury, thereby reducing the burden of kidney disease.
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Sun J, Li ZP, Zhang RQ, Zhang HM. Repression of miR-217 protects against high glucose-induced podocyte injury and insulin resistance by restoring PTEN-mediated autophagy pathway. Biochem Biophys Res Commun 2016; 483:318-324. [PMID: 28017719 DOI: 10.1016/j.bbrc.2016.12.145] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 12/21/2016] [Indexed: 12/20/2022]
Abstract
Podocyte damage is the initial hallmark of diabetic nephropathy (DN), leading to the increasing morbidity and mortality in diabetic patients. Recent researches have corroborated the critical roles of miRNAs in the pathological progression of DN. Here, elevation of miR-217 was verified in high glucose (HG)-stimulated podocytes. Moreover, blocking miR-217 expression antagonized HG-induced cell injury by attenuating the adverse role of HG on cell viability and inhibiting ROS levels and cell apoptosis. Simultaneously, miR-217 repression restored HG-disrupted insulin resistance by elevating glucose uptake and nephrin expression, an essential component for insulin-induced glucose uptake. Mechanism assay substantiated the defective autophagy in HG-treated podocytes, which was resumed by miR-217 cessation. Importantly, suppressing autophagy pathway with 3-MA alleviated the protective roles of miR-217 down-regulation in podocyte injury and insulin resistance. Luciferase reporter analysis confirmed that PTEN was a target of miR-217 in podocytes. Additionally, blocking PTEN expression restrained autophagy restoration in miR-217-decreased cells. Furthermore, PTEN down-regulation attenuated the beneficial role of miR-217 suppression in HG-induced injury and insulin resistance. Together, this study manifests that miR-217inhibition can protectively antagonize HG-induced podocyte damage and insulin resistance by restoring the defective autophagy pathway via targeting PTEN, representing a novel and promising therapeutic target against diabetic nephropathy.
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Affiliation(s)
- Juan Sun
- School of Nursing, Xinxiang Medical University, Xinxiang, Henan, 453003, PR China
| | - Zhao Pin Li
- School of International Education, Xin Xiang Medical University, Xinxiang, Henan, 453003, PR China
| | - Rui Qin Zhang
- School of Nursing, Xinxiang Medical University, Xinxiang, Henan, 453003, PR China
| | - Hui Min Zhang
- School of Nursing, Xinxiang Medical University, Xinxiang, Henan, 453003, PR China.
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Wasik AA, Dumont V, Tienari J, Nyman TA, Fogarty CL, Forsblom C, Lehto M, Lehtonen E, Groop PH, Lehtonen S. Septin 7 reduces nonmuscle myosin IIA activity in the SNAP23 complex and hinders GLUT4 storage vesicle docking and fusion. Exp Cell Res 2016; 350:336-348. [PMID: 28011197 PMCID: PMC5243148 DOI: 10.1016/j.yexcr.2016.12.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/10/2016] [Accepted: 12/17/2016] [Indexed: 12/28/2022]
Abstract
Glomerular epithelial cells, podocytes, are insulin responsive and can develop insulin resistance. Here, we demonstrate that the small GTPase septin 7 forms a complex with nonmuscle myosin heavy chain IIA (NMHC-IIA; encoded by MYH9), a component of the nonmuscle myosin IIA (NM-IIA) hexameric complex. We observed that knockdown of NMHC-IIA decreases insulin-stimulated glucose uptake into podocytes. Both septin 7 and NM-IIA associate with SNAP23, a SNARE protein involved in GLUT4 storage vesicle (GSV) docking and fusion with the plasma membrane. We observed that insulin decreases the level of septin 7 and increases the activity of NM-IIA in the SNAP23 complex, as visualized by increased phosphorylation of myosin regulatory light chain. Also knockdown of septin 7 increases the activity of NM-IIA in the complex. The activity of NM-IIA is increased in diabetic rat glomeruli and cultured human podocytes exposed to macroalbuminuric sera from patients with type 1 diabetes. Collectively, the data suggest that the activity of NM-IIA in the SNAP23 complex plays a key role in insulin-stimulated glucose uptake into podocytes. Furthermore, we observed that septin 7 reduces the activity of NM-IIA in the SNAP23 complex and thereby hinders GSV docking and fusion with the plasma membrane. Septin 7, nonmuscle myosin heavy chain IIA (NMHC-IIA) and SNAP23 form a complex. Knockdown of septin 7 increases NM-IIA activity in the SNAP23 complex. Insulin decreases septin 7 level and increases NM-IIA activity in the SNAP23 complex. Septin 7 hinders GSV docking/fusion by reducing NM-IIA activity in the SNAP23 complex.
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Affiliation(s)
- Anita A Wasik
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Vincent Dumont
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Jukka Tienari
- Department of Pathology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, 05850 Hyvinkää, Finland
| | - Tuula A Nyman
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Christopher L Fogarty
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Carol Forsblom
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Markku Lehto
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Eero Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland; Laboratory Animal Centre, University of Helsinki, 00014 Helsinki, Finland
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland; Baker IDI Heart & Diabetes Institute, 3004 Melbourne, Australia
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland.
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Abstract
IRS proteins are cellular adaptor molecules that mediate many of the key metabolic actions of insulin. When tyrosine is phosphorylated by the activated insulin receptor, IRS proteins recruit downstream effectors, such as phosphoinositide 3-kinase and mitogen-activated protein kinase, in order to elicit cellular responses such as glucose uptake, lipid metabolism and cell proliferation. There are two main IRS proteins in humans (IRS1 and IRS2), both of which are widely expressed. Given their central role in the insulin signalling pathway, it is not surprising that male mice lacking Irs1 or Irs2 present with elevated blood glucose or type 2 diabetes, respectively. For reasons yet to be identified, female Irs2 (-/-) mice do not develop type 2 diabetes. A number of organs are affected by complications of diabetes; macrovascular complications include stroke and coronary artery disease, while nephropathy, neuropathy and retinopathy fall into the category of microvascular complications. Given the serious consequences of these complications on patient morbidity and mortality, it is essential to identify the molecular pathogenesis underlying diabetic complications, with a view to improving therapeutic intervention and patient outcomes. A number of recently published papers have converged on the hypothesis that the loss of insulin signalling and IRS proteins is instrumental to the development and/or progression of diabetic complications. This review will summarise some highlights from the published work in which this hypothesis is discussed.
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Affiliation(s)
- Deborah P Lavin
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland, UK
| | - Morris F White
- Division of Endocrinology, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
| | - Derek P Brazil
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland, UK.
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Jiang S, He H, Tan L, Wang L, Su Z, Liu Y, Zhu H, Zhang M, Hou FF, Li A. Proteomic and phosphoproteomic analysis of renal cortex in a salt-load rat model of advanced kidney damage. Sci Rep 2016; 6:35906. [PMID: 27775022 PMCID: PMC5075906 DOI: 10.1038/srep35906] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 10/07/2016] [Indexed: 12/21/2022] Open
Abstract
Salt plays an essential role in the progression of chronic kidney disease and hypertension. However, the mechanisms underlying pathogenesis of salt-induced kidney damage remain largely unknown. Here, Sprague-Dawley rats, that underwent 5/6 nephrectomy (5/6Nx, a model of advanced kidney damage) or sham operation, were treated for 2 weeks with a normal or high-salt diet. We employed aTiO2 enrichment, iTRAQ labeling and liquid-chromatography tandem mass spectrometry strategy for proteomic and phosphoproteomic profiling of the renal cortex. We found 318 proteins differentially expressed in 5/6Nx group relative to sham group, and 310 proteins significantly changed in response to salt load in 5/6Nx animals. Totally, 1810 unique phosphopeptides corresponding to 550 phosphoproteins were identified. We identified 113 upregulated and 84 downregulated phosphopeptides in 5/6Nx animals relative to sham animals. Salt load induced 78 upregulated and 91 downregulated phosphopeptides in 5/6Nx rats. The differentially expressed phospholproteins are important transporters, structural molecules, and receptors. Protein-protein interaction analysis revealed that the differentially phosphorylated proteins in 5/6Nx group, Polr2a, Srrm1, Gsta2 and Pxn were the most linked. Salt-induced differential phosphoproteins, Myh6, Lmna and Des were the most linked. Altered phosphorylation levels of lamin A and phospholamban were validated. This study will provide new insight into pathogenetic mechanisms of chronic kidney disease and salt sensitivity.
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Affiliation(s)
- Shaoling Jiang
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hanchang He
- The First People's Foshan Hospital, Foshan, China
| | - Lishan Tan
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Liangliang Wang
- Division of Nephrology, First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, Guangzhou 510405, P.R. China
| | - Zhengxiu Su
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yufeng Liu
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hongguo Zhu
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Menghuan Zhang
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Fan Fan Hou
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Aiqing Li
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
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Abstract
Insulin resistance is a systemic disorder that affects many organs and insulin-regulated pathways. The disorder is characterized by a reduced action of insulin despite increased insulin concentrations (hyperinsulinaemia). The effects of insulin on the kidney and vasculature differ in part from the effects on classical insulin target organs. Insulin causes vasodilation by enhancing endothelial nitric oxide production through activation of the phosphatidylinositol 3-kinase pathway. In insulin-resistant states, this pathway is impaired and the mitogen-activated protein kinase pathway stimulates vasoconstriction. The action of insulin on perivascular fat tissue and the subsequent effects on the vascular wall are not fully understood, but the hepatokine fetuin-A, which is released by fatty liver, might promote the proinflammatory effects of perivascular fat. The strong association of salt-sensitive arterial hypertension with insulin resistance indicates an involvement of the kidney in the insulin resistance syndrome. The insulin receptor is expressed on renal tubular cells and podocytes and insulin signalling has important roles in podocyte viability and tubular function. Renal sodium transport is preserved in insulin resistance and contributes to the salt-sensitivity of blood pressure in hyperinsulinaemia. Therapeutically, renal and vascular insulin resistance can be improved by an integrated holistic approach aimed at restoring overall insulin sensitivity and improving insulin signalling.
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40
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Xin W, Li Z, Xu Y, Yu Y, Zhou Q, Chen L, Wan Q. Autophagy protects human podocytes from high glucose-induced injury by preventing insulin resistance. Metabolism 2016; 65:1307-15. [PMID: 27506738 DOI: 10.1016/j.metabol.2016.05.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 05/05/2016] [Accepted: 05/24/2016] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Insulin resistance is correlated with the progress of albuminuria in diabetic patients, and podocytes are crucial for maintaining the normal function of the glomerular filtration barrier. In the present study, we aimed to investigate the high glucose-induced insulin resistance and cell injury in human podocytes and the putative role of autophagy in this process. METHODS Human podocytes were cultured in high glucose-supplemented medium and low glucose and high osmotic conditions were used for the controls. Autophagy in the podocytes was regulated using rapamycin or 3-methyladenine stimulation. Next, autophagy markers including LC3B, Beclin-1, and p62 were investigated using western blot and qPCR, and the insulin responsiveness was analyzed based on glucose uptake and by using the phosphorylation of the insulin receptor with Nephrin as a podocyte injury marker. RESULTS The basal autophagy level decreased under the high glucose conditions, which was accompanied by a decrease in the glucose uptake and phosphorylation of the insulin receptor in the human podocytes. More interestingly, the glucose uptake and the phosphorylation of the insulin receptor were decreased by 3-MA stimulation and increased by rapamycin, illustrating that the responsiveness of insulin was regulated by autophagy. The activation of autophagy by rapamycin also ameliorated cell injury in the human podocytes. CONCLUSIONS The presence or activation of autophagy was found to play a protective role in human podocytes against high glucose-induced insulin resistance and cell injury, which indicates a novel cellular mechanism and provides a potential therapeutic target for diabetic nephropathy (DN).
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Affiliation(s)
- Wei Xin
- Department of Central Laboratory, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China
| | - Zhaoping Li
- Institute of Nutrition and Food Hygiene, School of Public Health, Shandong University, Jinan, 250012, China
| | - Ying Xu
- Department of Nephrology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China
| | - Yue Yu
- Institute of Nutrition and Food Hygiene, School of Public Health, Shandong University, Jinan, 250012, China
| | - Qi Zhou
- School of Medicine, Shandong University, Jinan, 250012, China
| | - Liyong Chen
- Department of Nutrition, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China.
| | - Qiang Wan
- Department of Nephrology, Qianfoshan Hospital Affiliated to Shandong University, Jinan, 250014, China.
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41
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Logue OC, McGowan JWD, George EM, Bidwell GL. Therapeutic angiogenesis by vascular endothelial growth factor supplementation for treatment of renal disease. Curr Opin Nephrol Hypertens 2016; 25:404-9. [PMID: 27367910 PMCID: PMC4974125 DOI: 10.1097/mnh.0000000000000256] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
PURPOSE OF REVIEW Vascular endothelial growth factors (VEGFs) influence renal function through angiogenesis, with VEGF-A being the most potent inducer of vascular formation. In the normal glomerulus, tight homeostatic balance is maintained between the levels of VEGF-A isoforms produced by podocyte cells, and the VEGF receptors (VEGFRs) expressed by glomerular endothelial, mesangial, and podocyte cells. Renal disease occurs when this homeostatic balance is lost, manifesting in the abnormal autocrine and paracrine VEGF-A/VEGFR signaling, ultrastructural glomerular and tubular damage, and impaired filtration. RECENT FINDINGS Preclinical disease models of ischemic renal injury, including acute ischemia/reperfusion, thrombotic microangiopathy, and chronic renovascular disease, treated with exogenous VEGF supplementation demonstrated therapeutic efficacy. These results suggest a therapeutic VEGF-A paracrine effect on endothelial cells in the context of acute or chronic obstructive ischemia. Conversely, renal dysfunction in diabetic nephropathy appears to occur through an upregulated VEGF autocrine effect on podocyte cells, which is exacerbated by hyperglycemia. Therefore, VEGF supplementation therapy may be contraindicated for treatment of diabetic nephropathy, but specific results will depend on dose and on the specific site of VEGF delivery. A drug delivery system that demonstrates cell specificity for glomerular or peritubular capillaries could be employed to restore balance to VEGF-A/VEGFR2 signaling, and by doing so, prevent the progression to end-stage renal disease. SUMMARY The review discusses the preclinical data available for VEGF supplementation therapy in models of renal disease.
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Affiliation(s)
- Omar C. Logue
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS
| | | | - Eric M. George
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, MS
| | - Gene L. Bidwell
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, MS
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42
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Zhang J, Fu H, Xu Y, Niu Y, An X. Hyperoside reduces albuminuria in diabetic nephropathy at the early stage through ameliorating renal damage and podocyte injury. J Nat Med 2016; 70:740-8. [PMID: 27255369 DOI: 10.1007/s11418-016-1007-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 04/30/2016] [Indexed: 02/07/2023]
Abstract
Diabetic nephropathy (DN) is one of the major microvascular complications in diabetes. Podocyte injury such as slit diaphragm effacement is regarded as a determinant in the occurrence and development of albuminuria in DN. In this study, we examined the effect of hyperoside, an active flavonoid glycoside, on proteinuria and renal damage in a streptozotocin-induced DN mouse model at the early stage. The results showed that oral administration of hyperoside (30 mg/kg/day for 4 weeks could significantly decrease urinary microalbumin excretion and glomerular hyperfiltration in DN mice, but did not affect the glucose and lipid metabolism. Periodic acid-Schiff staining and transmission electron microscopy showed that glomerular mesangial matrix expansion and podocyte process effacement in DN mice were significantly improved by hyperoside. Further investigations via immunofluorescence staining, real-time reverse transcription polymerase chain reaction and Western blot analysis showed that the decreased slit diaphragm protein nephrin and podocin mRNA expression and protein levels in DN mice were restored by hyperoside treatment. Collectively, these findings demonstrated that hyperoside could decrease albuminuria at the early stage of DN by ameliorating renal damage and podocyte injury.
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Affiliation(s)
- Jisheng Zhang
- Department of Otorhinolaryngology, Affiliated Hospital of Qingdao University, 266003, Qingdao, China
- Department of Endocrinology, Jiangsu Province Hospital of Chinese Medicine, 210029, Nanjing, China
| | - Haiyan Fu
- Department of Nephrology, Nanfang Hospital, Southern Medical University, 510515, Guangzhou, China
| | - Yan Xu
- Department of Otorhinolaryngology, Affiliated Hospital of Qingdao University, 266003, Qingdao, China
| | - Yunfei Niu
- Department of Bone Molecular Biology, Changhai Hospital, The Second Military University, 200433, Shanghai, China
| | - Xiaofei An
- Department of Endocrinology, Jiangsu Province Hospital of Chinese Medicine, 210029, Nanjing, China.
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43
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Abstract
Diabetes is increasing in prevalence and is the leading cause of end-stage renal disease in the United States. Diabetic kidney disease is considered a proteinuric glomerular disease. Although the glomerulus is composed of various cell types, research suggests that podocytes are critical to overall glomerular health. Podocyte injury has been identified as a pivotal event resulting in proteinuric kidney disease, glomerulosclerosis, and loss of renal function. Thus, understanding the signaling mechanisms that trigger podocyte injury in diabetic kidney disease might allow for the development of targeted therapeutics to prevent or ameliorate progression to end-stage renal failure. This review focuses on the role of podocytes in diabetic kidney disease.
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Affiliation(s)
- Jamie S Lin
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katalin Susztak
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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44
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Xu Y, Zhou Q, Xin W, Li Z, Chen L, Wan Q. Autophagy downregulation contributes to insulin resistance mediated injury in insulin receptor knockout podocytes in vitro. PeerJ 2016; 4:e1888. [PMID: 27077005 PMCID: PMC4830256 DOI: 10.7717/peerj.1888] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/13/2016] [Indexed: 12/30/2022] Open
Abstract
It is unknown whether autophagy activity is altered in insulin resistant podocytes and whether autophagy could be a therapeutic target for diabetic nephropathy (DN). Here we used shRNA transfection to knockdown the insulin receptor (IR) gene in cultured human immortalized podocytes as an in vitro insulin resistant model. Autophagy related proteins LC3, Beclin, and p62 as well as nephrin, a podocyte injury marker, were assessed using western blot and immunofluorescence staining. Our results show that autophagy is suppressed when podocytes lose insulin sensitivity and that treatment of rapamycin, an mTOR specific inhibitor, could attenuate insulin resistance induced podocytes injury via autophagy activation. The present study deepens our understanding of the role of autophagy in the pathogenesis of DN.
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Affiliation(s)
- Ying Xu
- Department of Nephrology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China
| | - Qi Zhou
- School of Medicine, Shandong University, Jinan, Shandong, China
| | - Wei Xin
- Central Lab, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China
| | - Zhaoping Li
- School of Public Health, Shandong University, Jinan, Shandong, China
| | - Liyong Chen
- Department of Nutrition, Shandong Provincial Hospital Affiliated to Shandong Hospital, Jinan, Shandong, China
| | - Qiang Wan
- Department of Nephrology, Qianfoshan Hospital Affiliated to Shandong University, Jinan, Shandong, China
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45
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Lehtonen S, Jalanko H. Nephrin Trafficking beyond the Kidney--Role in Glucose-Stimulated Insulin Secretion in β Cells. J Am Soc Nephrol 2015; 27:965-8. [PMID: 26400568 DOI: 10.1681/asn.2015080960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Sanna Lehtonen
- Department of Pathology, University of Helsinki, Helsinki, Finland; and
| | - Hannu Jalanko
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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46
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Villarreal R, Mitrofanova A, Maiguel D, Morales X, Jeon J, Grahammer F, Leibiger IB, Guzman J, Fachado A, Yoo TH, Busher Katin A, Gellermann J, Merscher S, Burke GW, Berggren PO, Oh J, Huber TB, Fornoni A. Nephrin Contributes to Insulin Secretion and Affects Mammalian Target of Rapamycin Signaling Independently of Insulin Receptor. J Am Soc Nephrol 2015; 27:1029-41. [PMID: 26400569 DOI: 10.1681/asn.2015020210] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/19/2015] [Indexed: 12/31/2022] Open
Abstract
Nephrin belongs to a family of highly conserved proteins with a well characterized function as modulators of cell adhesion and guidance, and nephrin may have a role in metabolic pathways linked to podocyte and pancreatic β-cell survival. However, this role is incompletely characterized. In this study, we developed floxed nephrin mice for pancreatic β-cell-specific deletion of nephrin, which had no effect on islet size and glycemia. Nephrin deficiency, however, resulted in glucose intolerance in vivo and impaired glucose-stimulated insulin release ex vivo Glucose intolerance was also observed in eight patients with nephrin mutations compared with three patients with other genetic forms of nephrotic syndrome or nine healthy controls.In vitro experiments were conducted to investigate if nephrin affects autocrine signaling through insulin receptor A (IRA) and B (IRB), which are both expressed in human podocytes and pancreatic islets. Coimmunoprecipitation of nephrin and IRB but not IRA was observed and required IR phosphorylation. Nephrin per se was sufficient to induce phosphorylation of p70S6K in an phosphatidylinositol 3-kinase-dependent but IR/Src-independent manner, which was not augmented by exogenous insulin. These results suggest a role for nephrin as an independent modulator of podocyte and pancreatic β-cell nutrient sensing in the fasting state and the potential of nephrin as a drug target in diabetes.
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Affiliation(s)
- Rodrigo Villarreal
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Alla Mitrofanova
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and
| | - Dony Maiguel
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Ximena Morales
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and
| | - Jongmin Jeon
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida
| | | | - Ingo B Leibiger
- Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Johanna Guzman
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Alberto Fachado
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Tae H Yoo
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and Department of Internal Medicine, Division of Nephrology, Yonsei University College of Medicine, Seoul, Korea
| | - Anja Busher Katin
- Pediatric Nephrology, Pediatrics II, University Children's Hospital Essen, Essen, Germany
| | - Jutta Gellermann
- Department of Pediatric Nephrology, Charité Children's Hospital, Berlin, Germany
| | - Sandra Merscher
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - George W Burke
- Department of Surgery, University of Miami, Miami, Florida; and
| | - Per-Olof Berggren
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida; Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Jun Oh
- Pediatric Nephrology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tobias B Huber
- Renal Division, University Hospital Freiburg, Freiburg, Germany
| | - Alessia Fornoni
- Katz Family Drug Discovery Center, Division of Nephrology and Hypertension and Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida;
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47
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IRS2 and PTEN are key molecules in controlling insulin sensitivity in podocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3224-34. [PMID: 26384875 DOI: 10.1016/j.bbamcr.2015.09.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 09/01/2015] [Accepted: 09/14/2015] [Indexed: 01/03/2023]
Abstract
Insulin signaling to the glomerular podocyte is important for normal kidney function and is implicated in the pathogenesis of diabetic nephropathy (DN). This study determined the role of the insulin receptor substrate 2 (IRS2) in this system. Conditionally immortalized murine podocytes were generated from wild-type (WT) and insulin receptor substrate 2-deficient mice (Irs2(-/-)). Insulin signaling, glucose transport, cellular motility and cytoskeleton rearrangement were then analyzed. Within the glomerulus IRS2 is enriched in the podocyte and is preferentially phosphorylated by insulin in comparison to IRS1. Irs2(-/-) podocytes are significantly insulin resistant in respect to AKT signaling, insulin-stimulated GLUT4-mediated glucose uptake, filamentous actin (F-actin) cytoskeleton remodeling and cell motility. Mechanistically, we discovered that Irs2 deficiency causes insulin resistance through up-regulation of the phosphatase and tensin homolog (PTEN). Importantly, suppressing PTEN in Irs2(-/-) podocytes rescued insulin sensitivity. In conclusion, this study has identified for the first time IRS2 as a critical molecule for sensitizing the podocyte to insulin actions through its ability to modulate PTEN expression. This finding reveals two potential molecular targets in the podocyte for modulating insulin sensitivity and treating DN.
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48
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Insulin signaling: implications for podocyte biology in diabetic kidney disease. Curr Opin Nephrol Hypertens 2015; 24:104-10. [PMID: 25415617 DOI: 10.1097/mnh.0000000000000078] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Several key elements of the insulin signaling cascade contribute to podocyte function and survival. While it was initially thought that the consequences of altered insulin signaling to podocyte function was strictly related to altered glucose uptake, it has become clear that upstream signaling events involved in cell survival, lipid metabolism or nutrient sensing and modulated by insulin are strong independent contributors to podocyte function. RECENT FINDINGS Akt2, the major isoform of Akt activated following cellular insulin stimulation, protects against the progression of renal disease in nephron-deficient mice, and podocyte-specific deletion of Akt2 results in a more rapid progression of experimental glomerular disease. In diabetes, podocyte mammalian target of rapamycin activation clearly contributes to podocyte injury and regulated autophagy. Furthermore, podocyte-specific glucose transporter type 4 (GLUT4) deficiency protects podocytes by preventing mammalian target of rapamycin signaling independently of glucose uptake. Finally, intracellular lipids have been recently recognized as major modulators of podocyte insulin signaling and as a new therapeutic target. SUMMARY The identification of new contributors to podocyte insulin signaling is of extreme translational value as it may lead to new drug development strategies for diabetic kidney disease, as well as for other proteinuric kidney diseases.
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49
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Abstract
Progressive renal impairment (diabetic kidney disease (DKD)) occurs in upwards of 40 % of patients with obesity and type 2 diabetes mellitus (T2DM) and is a cause of significant morbidity and mortality. Means of attenuating the progression of DKD focus on amelioration of risk factors. Visceral obesity is implicated as a causative agent in impaired metabolic and cardiovascular control in T2DM, and various approaches primarily targeting weight have been examined for their impact on markers of renal injury and dysfunction in DKD. The current report summarises the evidence base for the impact of surgical, lifestyle and pharmacological approaches to weight loss on renal end points in DKD. The potential for a threshold of weight loss more readily achievable by surgical intervention to be a prerequisite for renal improvement is highlighted. Comparing efficacious non-surgical weight loss strategies with surgical strategies in appropriately powered and controlled prospective studies is a priority for the field.
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Affiliation(s)
- Neil G Docherty
- Diabetes Complications Research Centre, Conway Institute, School of Medicine and Medical Sciences, University College Dublin, Belfield, Ireland,
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50
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Na J, Sweetwyne MT, Park ASD, Susztak K, Cagan RL. Diet-Induced Podocyte Dysfunction in Drosophila and Mammals. Cell Rep 2015; 12:636-47. [PMID: 26190114 DOI: 10.1016/j.celrep.2015.06.056] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 05/15/2015] [Accepted: 06/17/2015] [Indexed: 01/15/2023] Open
Abstract
Diabetic nephropathy is a major cause of end-stage kidney disease. Characterized by progressive microvascular disease, most efforts have focused on injury to the glomerular endothelium. Recent work has suggested a role for the podocyte, a highly specialized component of the glomerular filtration barrier. Here, we demonstrate that the Drosophila nephrocyte, a cell analogous to the mammalian podocyte, displays defects that phenocopy aspects of diabetic nephropathy in animals fed chronic high dietary sucrose. Through functional studies, we identify an OGT-Polycomb-Knot-Sns pathway that links dietary sucrose to loss of the Nephrin ortholog Sns. Reducing OGT through genetic or drug means is sufficient to rescue loss of Sns, leading to overall extension of lifespan. We demonstrate upregulation of the Knot ortholog EBF2 in glomeruli of human diabetic nephropathy patients and a mouse ob/ob diabetes model. Furthermore, we demonstrate rescue of Nephrin expression and cell viability in ebf2(-/-) primary podocytes cultured in high glucose.
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Affiliation(s)
- Jianbo Na
- Department of Developmental and Regenerative Biology and School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029-1020, USA
| | - Mariya T Sweetwyne
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, 405B Clinical Research Building, Philadelphia, PA 19104-4539, USA
| | - Ae Seo Deok Park
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, 405B Clinical Research Building, Philadelphia, PA 19104-4539, USA
| | - Katalin Susztak
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, 405B Clinical Research Building, Philadelphia, PA 19104-4539, USA
| | - Ross L Cagan
- Department of Developmental and Regenerative Biology and School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029-1020, USA.
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