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Wang L, Wang HL, Liu TT, Lan HY. TGF-Beta as a Master Regulator of Diabetic Nephropathy. Int J Mol Sci 2021; 22:7881. [PMID: 34360646 PMCID: PMC8345981 DOI: 10.3390/ijms22157881] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 07/13/2021] [Accepted: 07/13/2021] [Indexed: 12/26/2022] Open
Abstract
Diabetic nephropathy (DN) is one of the most common complications in diabetes mellitus and the leading cause of end-stage renal disease. TGF-β is a pleiotropic cytokine and has been recognized as a key mediator of DN. However, anti-TGF-β treatment for DN remains controversial due to the diverse role of TGF-β1 in DN. Thus, understanding the regulatory role and mechanisms of TGF-β in the pathogenesis of DN is the initial step towards the development of anti-TGF-β treatment for DN. In this review, we first discuss the diverse roles and signaling mechanisms of TGF-β in DN by focusing on the latent versus active TGF-β1, the TGF-β receptors, and the downstream individual Smad signaling molecules including Smad2, Smad3, Smad4, and Smad7. Then, we dissect the regulatory mechanisms of TGF-β/Smad signaling in the development of DN by emphasizing Smad-dependent non-coding RNAs including microRNAs and long-non-coding RNAs. Finally, the potential therapeutic strategies for DN by targeting TGF-β signaling with various therapeutic approaches are discussed.
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Affiliation(s)
- Li Wang
- Research Center for Integrative Medicine, Affiliated Traditional Medicine Hospital of Southwest Medical University, Luzhou 646000, China; (L.W.); (H.-L.W.); (T.-T.L.)
| | - Hong-Lian Wang
- Research Center for Integrative Medicine, Affiliated Traditional Medicine Hospital of Southwest Medical University, Luzhou 646000, China; (L.W.); (H.-L.W.); (T.-T.L.)
| | - Tong-Tong Liu
- Research Center for Integrative Medicine, Affiliated Traditional Medicine Hospital of Southwest Medical University, Luzhou 646000, China; (L.W.); (H.-L.W.); (T.-T.L.)
| | - Hui-Yao Lan
- Department of Medicine and Therapeutics, and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong 999077, China
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Maity S, Das F, Kasinath BS, Ghosh-Choudhury N, Ghosh Choudhury G. TGFβ acts through PDGFRβ to activate mTORC1 via the Akt/PRAS40 axis and causes glomerular mesangial cell hypertrophy and matrix protein expression. J Biol Chem 2020; 295:14262-14278. [PMID: 32732288 DOI: 10.1074/jbc.ra120.014994] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/27/2020] [Indexed: 12/21/2022] Open
Abstract
Interaction of transforming growth factor-β (TGFβ)-induced canonical signaling with the noncanonical kinase cascades regulates glomerular hypertrophy and matrix protein deposition, which are early features of glomerulosclerosis. However, the specific target downstream of the TGFβ receptor involved in the noncanonical signaling is unknown. Here, we show that TGFβ increased the catalytic loop phosphorylation of platelet-derived growth factor receptor β (PDGFRβ), a receptor tyrosine kinase expressed abundantly in glomerular mesangial cells. TGFβ increased phosphorylation of the PI 3-kinase-interacting Tyr-751 residue of PDGFRβ, thus activating Akt. Inhibition of PDGFRβ using a pharmacological inhibitor and siRNAs blocked TGFβ-stimulated phosphorylation of proline-rich Akt substrate of 40 kDa (PRAS40), an intrinsic inhibitory component of mTORC1, and prevented activation of mTORC1 in the absence of any effect on Smad 2/3 phosphorylation. Expression of constitutively active myristoylated Akt reversed the siPDGFRβ-mediated inhibition of mTORC1 activity; however, co-expression of the phospho-deficient mutant of PRAS40 inhibited the effect of myristoylated Akt, suggesting a definitive role of PRAS40 phosphorylation in mTORC1 activation downstream of PDGFRβ in mesangial cells. Additionally, we demonstrate that PDGFRβ-initiated phosphorylation of PRAS40 is required for TGFβ-induced mesangial cell hypertrophy and fibronectin and collagen I (α2) production. Increased activating phosphorylation of PDGFRβ is also associated with enhanced TGFβ expression and mTORC1 activation in the kidney cortex and glomeruli of diabetic mice and rats, respectively. Thus, pursuing TGFβ noncanonical signaling, we identified how TGFβ receptor I achieves mTORC1 activation through PDGFRβ-mediated Akt/PRAS40 phosphorylation to spur mesangial cell hypertrophy and matrix protein accumulation. These findings provide support for targeting PDGFRβ in TGFβ-driven renal fibrosis.
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Affiliation(s)
- Soumya Maity
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Falguni Das
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Balakuntalam S Kasinath
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA.,Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
| | | | - Goutam Ghosh Choudhury
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas, USA .,Department of Veterans Affairs Research, South Texas Veterans Health Care System, San Antonio, Texas, USA.,Geriatric Research, Education, and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas, USA
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3
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Endothelial heparan sulfate deficiency reduces inflammation and fibrosis in murine diabetic nephropathy. J Transl Med 2018; 98:427-438. [PMID: 29330473 PMCID: PMC6247417 DOI: 10.1038/s41374-017-0015-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 11/22/2017] [Accepted: 12/14/2017] [Indexed: 01/08/2023] Open
Abstract
Inflammation plays a vital role in the development of diabetic nephropathy, but the underlying regulatory mechanisms are only partially understood. Our previous studies demonstrated that, during acute inflammation, endothelial heparan sulfate (HS) contributes to the adhesion and transendothelial migration of leukocytes into perivascular tissues by direct interaction with L-selectin and the presentation of bound chemokines. In the current study, we aimed to assess the role of endothelial HS on chronic renal inflammation and fibrosis in a diabetic nephropathy mouse model. To reduce sulfation of HS specifically in the endothelium, we generated Ndst1 f/f Tie2Cre + mice in which N-deacetylase/N-sulfotransferase-1 (Ndst1), the gene that initiates HS sulfation modifications in HS biosynthesis, was expressly ablated in endothelium. To induce diabetes, age-matched male Ndst1 f/f Tie2Cre - (wild type) and Ndst1 f/f Tie2Cre + mice on a C57Bl/6J background were injected intraperitoneally with streptozotocin (STZ) (50 mg/kg) on five consecutive days (N = 10-11/group). Urine and plasma were collected. Four weeks after diabetes induction the animals were sacrificed and kidneys were analyzed by immunohistochemistry and qRT-PCR. Compared to healthy controls, diabetic Ndst1 f/f Tie2Cre - mice showed increased glomerular macrophage infiltration, mannose binding lectin complement deposition and glomerulosclerosis, whereas these pathological reactions were prevented significantly in the diabetic Ndst1 f/f Tie2Cre + animals (all three p < 0.01). In addition, the expression of the podocyte damage marker desmin was significantly higher in the Ndst1 f/f Tie2Cre - group compared to the Ndst1 f/f Tie2Cre + animals (p < 0.001), although both groups had comparable numbers of podocytes. In the cortical tubulo-interstitium, similar analyses show decreased interstitial macrophage accumulation in the diabetic Ndst1 f/f Tie2Cre + animals compared to the diabetic Ndst1 f/f Tie2Cre - mice (p < 0.05). Diabetic Ndst1 f/f Tie2Cre + animals also showed reduced interstitial fibrosis as evidenced by reduced density of αSMA-positive myofibroblasts (p < 0.01), diminished collagen III deposition (p < 0.001) and reduced mRNA expression of collagen I (p < 0.001) and fibronectin (p < 0.001). Our studies indicate a pivotal role of endothelial HS in the development of renal inflammation and fibrosis in diabetic nephropathy in mice. These results suggest that HS is a possible target for therapy in diabetic nephropathy.
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Waters JP, Richards YC, Skepper JN, Southwood M, Upton PD, Morrell NW, Pober JS, Bradley JR. A 3D tri-culture system reveals that activin receptor-like kinase 5 and connective tissue growth factor drive human glomerulosclerosis. J Pathol 2017; 243:390-400. [PMID: 28815607 DOI: 10.1002/path.4960] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 06/21/2017] [Accepted: 08/10/2017] [Indexed: 11/11/2022]
Abstract
Glomerular scarring, known as glomerulosclerosis, occurs in many chronic kidney diseases and involves interaction between glomerular endothelial cells (GECs), podocytes, and mesangial cells (MCs), leading to signals that promote extracellular matrix deposition and endothelial cell dysfunction and loss. We describe a 3D tri-culture system to model human glomerulosclerosis. In 3D monoculture, each cell type alters its phenotype in response to TGFβ, which has been implicated as an important mediator of glomerulosclerosis. GECs form a lumenized vascular network, which regresses in response to TGFβ. MCs respond to TGFβ by forming glomerulosclerotic-like nodules with matrix deposition. TGFβ treatment of podocytes does not alter cell morphology but increases connective tissue growth factor (CTGF) expression. BMP7 prevents TGFβ-induced GEC network regression, whereas TGFβ-induced MC nodule formation is prevented by SMAD3 siRNA knockdown or ALK5 inhibitors but not BMP7, and increased phospho-SMAD3 was observed in human glomerulosclerosis. In 3D tri-culture, GECs, podocytes, and MCs form a vascular network in which GECs and podocytes interact intimately within a matrix containing MCs. TGFβ treatment induces formation of nodules, but combined inhibition of ALK5 and CTGF is required to prevent TGFβ-induced nodule formation in tri-cellular cultures. Identification of therapeutic targets for glomerulosclerosis depends on the 3D culture of all three glomerular cells. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- John P Waters
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - Yvonne C Richards
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - Jeremy N Skepper
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Mark Southwood
- Department of Pathology, Papworth Hospital, Papworth Everard, Cambridge, UK
| | - Paul D Upton
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - Nicholas W Morrell
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
| | - Jordan S Pober
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | - John R Bradley
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital and NIHR Cambridge Biomedical Research Centre, Cambridge, UK
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Das F, Ghosh-Choudhury N, Kasinath BS, Choudhury GG. Tyrosines-740/751 of PDGFRβ contribute to the activation of Akt/Hif1α/TGFβ nexus to drive high glucose-induced glomerular mesangial cell hypertrophy. Cell Signal 2017; 42:44-53. [PMID: 28951244 DOI: 10.1016/j.cellsig.2017.09.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 09/22/2017] [Indexed: 01/24/2023]
Abstract
Glomerular mesangial cell hypertrophy contributes to the complications of diabetic nephropathy. The mechanism by which high glucose induces mesangial cell hypertrophy is poorly understood. Here we explored the role of the platelet-derived growth factor receptor-β (PDGFRβ) tyrosine kinase in driving the high glucose-induced mesangial cell hypertrophy. We show that high glucose stimulates the association of the PDGFRβ with PI 3 kinase leading to tyrosine phosphorylation of the latter. High glucose-induced Akt kinase activation was also dependent upon PDGFRβ and its tyrosine phosphorylation at 740/751 residues. Inhibition of PDGFRβ activity, its downregulation and expression of its phospho-deficient (Y740/751F) mutant inhibited mesangial cell hypertrophy by high glucose. Interestingly, expression of constitutively active Akt reversed this inhibition, indicating a role of Akt kinase downstream of PDGFRβ phosphorylation in this process. The transcription factor Hif1α is a target of Akt kinase. siRNAs against Hif1α inhibited the high glucose-induced mesangial cell hypertrophy. In contrast, increased expression of Hif1α induced hypertrophy similar to high glucose. We found that inhibition of PDGFRβ and expression of PDGFRβ Y740/751F mutant significantly inhibited the high glucose-induced expression of Hif1α. Importantly, expression of Hif1α countered the inhibition of mesangial cell hypertrophy induced by siPDGFRβ or PDGFRβ Y740/751F mutant. Finally, we show that high glucose-stimulated PDGFRβ tyrosine phosphorylation at 740/751 residues and the tyrosine kinase activity of the receptor regulate the transforming growth factor-β (TGFβ) expression by Hif1α. Thus we define the cell surface PDGFRβ as a major link between high glucose and its effectors Hif1α and TGFβ for induction of diabetic mesangial cell hypertrophy.
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Affiliation(s)
- Falguni Das
- Department of Medicine, UT Health at San Antonio, TX, United States
| | - Nandini Ghosh-Choudhury
- VA Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, TX, United States; Department of Pathology, UT Health at San Antonio, TX, United States
| | - Balakuntalam S Kasinath
- Department of Medicine, UT Health at San Antonio, TX, United States; VA Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, TX, United States
| | - Goutam Ghosh Choudhury
- Department of Medicine, UT Health at San Antonio, TX, United States; VA Biomedical Laboratory Research, South Texas Veterans Health Care System, San Antonio, TX, United States; Geriatric Research, Education and Clinical Research, South Texas Veterans Health Care System, San Antonio, TX, United States.
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Das F, Ghosh-Choudhury N, Bera A, Dey N, Abboud HE, Kasinath BS, Choudhury GG. Transforming growth factor β integrates Smad 3 to mechanistic target of rapamycin complexes to arrest deptor abundance for glomerular mesangial cell hypertrophy. J Biol Chem 2013; 288:7756-7768. [PMID: 23362262 DOI: 10.1074/jbc.m113.455782] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In many renal diseases, transforming growth factor β (TGFβ)-stimulated canonical Smad 3 and noncanonical mechanistic target of rapamycin (mTOR) promote increased protein synthesis and mesangial cell hypertrophy. The cellular underpinnings involving these signaling molecules to regulate mesangial cell hypertrophy are not fully understood. Deptor has recently been identified as an mTOR interacting protein and functions as an endogenous inhibitor of the kinase activity for both TORC1 and TORC2. Prolonged incubation of mesangial cells with TGFβ reduced the levels of deptor concomitant with an increase in TORC1 and TORC2 activity. Sustained TGFβ activation was required to inhibit association of deptor with mTOR, whereas rapid activation had no effect. Using the mTOR inhibitor PP242, we found that TGFβ-induced both early and sustained activation of TORC1 and TORC2 was necessary for deptor suppression. PP242-induced reversal of deptor suppression by TGFβ was associated with a significant inhibition of TGFβ-stimulated protein synthesis and hypertrophy. Interestingly, expression of siRNA against Smad 3 or Smad 7, which blocks TGFβ receptor-specific Smad 3 signaling, prevented TGFβ-induced suppression of deptor abundance and TORC1/2 activities. Furthermore, overexpression of Smad 3 decreased deptor expression similar to TGFβ stimulation concomitant with increased TORC1 and TORC2 activities. Finally, knockdown of deptor reversed Smad 7-mediated inhibition of protein synthesis and mesangial cell hypertrophy induced by TGFβ. These data reveal the requirement of both early and late activation of mTOR for TGFβ-induced protein synthesis. Our results support that TGFβ-stimulated Smad 3 acts as a key node to instill a feedback loop between deptor down-regulation and TORC1/2 activation in driving mesangial cell hypertrophy.
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Affiliation(s)
- Falguni Das
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Nandini Ghosh-Choudhury
- Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229; Veterans Affairs Research, South Texas Veterans Health Care System, San Antonio, Texas 78229
| | - Amit Bera
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Nirmalya Dey
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Hanna E Abboud
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229; Veterans Affairs Research, South Texas Veterans Health Care System, San Antonio, Texas 78229
| | - Balakuntalam S Kasinath
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229; Veterans Affairs Research, South Texas Veterans Health Care System, San Antonio, Texas 78229
| | - Goutam Ghosh Choudhury
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229; Veterans Affairs Research, South Texas Veterans Health Care System, San Antonio, Texas 78229; Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas 78229.
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Mechanisms and consequences of TGF-ß overexpression by podocytes in progressive podocyte disease. Cell Tissue Res 2011; 347:129-40. [PMID: 21541658 PMCID: PMC3250617 DOI: 10.1007/s00441-011-1169-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 04/04/2011] [Indexed: 01/21/2023]
Abstract
In patients with progressive podocyte disease, such as focal segmental glomerulosclerosis (FSGS) and membranous nephropathy, upregulation of transforming growth factor-ß (TGF-ß) is observed in podocytes. Mechanical pressure or biomechanical strain in podocytopathies may cause overexpression of TGF-ß and angiotensin II (Ang II). Oxidative stress induced by Ang II may activate the latent TGF-ß, which then activates Smads and Ras/extracellular signal-regulated kinase (ERK) signaling pathways in podocytes. Enhanced TGF-ß activity in podocytes may lead to thickening of the glomerular basement membrane (GBM) by overproduction of GBM proteins and impaired GBM degradation in podocyte disease. It may also lead to podocyte apoptosis and detachment from the GBM, and epithelial-mesenchymal transition (EMT) of podocytes, initiating the development of glomerulosclerosis. Furthermore, activated TGF-ß/Smad signaling by podocytes may induce connective tissue growth factor and vascular endothelial growth factor overexpression, which could act as a paracrine effector mechanism on mesangial cells to stimulate mesangial matrix synthesis. In proliferative podocytopathies, such as cellular or collapsing FSGS, TGF-ß-induced ERK activation may play a role in podocyte proliferation, possibly via TGF-ß-induced EMT of podocytes. Collectively, these data bring new mechanistic insights into our understanding of the TGF-ß overexpression by podocytes in progressive podocyte disease.
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TGFβ enforces activation of eukaryotic elongation factor-2 (eEF2) via inactivation of eEF2 kinase by p90 ribosomal S6 kinase (p90Rsk) to induce mesangial cell hypertrophy. FEBS Lett 2010; 584:4268-72. [PMID: 20837011 DOI: 10.1016/j.febslet.2010.09.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/24/2010] [Accepted: 09/03/2010] [Indexed: 12/11/2022]
Abstract
eEF2 phosphorylation is under tight control to maintain mRNA translation elongation. We report that TGFβ activates eEF2 by decreasing eEF2 phosphorylation and simultaneously increasing eEF2 kinase phosphorylation. Remarkably, inhibition of Erk1/2 blocked the TGFβ-induced dephosphorylation and phosphorylation of eEF2 and eEF2 kinase. TGFβ increased phosphorylation of p90Rsk in an Erk1/2-dependent manner. Inactive p90Rsk reversed TGFβ-inhibited phosphorylation of eEF2 and suppressed eEF2 kinase activity. Finally, inactive p90Rsk significantly attenuated TGFβ-induced protein synthesis and hypertrophy of mesangial cells. These results present the first evidence that TGFβ utilizes the two layered kinase module Erk/p90Rsk to activate eEF2 for increased protein synthesis during cellular hypertrophy.
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Roxburgh SA, Kattla JJ, Curran SP, O'Meara YM, Pollock CA, Goldschmeding R, Godson C, Martin F, Brazil DP. Allelic depletion of grem1 attenuates diabetic kidney disease. Diabetes 2009; 58:1641-50. [PMID: 19401426 PMCID: PMC2699858 DOI: 10.2337/db08-1365] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
OBJECTIVE Gremlin (grem1) is an antagonist of the bone morphogenetic protein family that plays a key role in limb bud development and kidney formation. There is a growing appreciation that altered grem1 expression may regulate the homeostatic constraints on damage responses in diseases such as diabetic nephropathy. RESEARCH DESIGN AND METHODS Here we explored whether knockout mice heterozygous for grem1 gene deletion (grem1(+/-)) exhibit protection from the progression of diabetic kidney disease in a streptozotocin-induced model of type 1 diabetes. RESULTS A marked elevation in grem1 expression was detected in the kidneys and particularly in kidney tubules of diabetic wild-type mice compared with those of littermate controls. In contrast, diabetic grem1(+/-) mice displayed a significant attenuation in grem1 expression at 6 months of diabetes compared with that in age- and sex-matched wild-type controls. Whereas the onset and induction of diabetes were similar between grem1(+/-) and wild-type mice, several indicators of diabetes-associated kidney damage such as increased glomerular basement membrane thickening and microalbuminuria were attenuated in grem1(+/-) mice compared with those in wild-type controls. Markers of renal damage such as fibronectin and connective tissue growth factor were elevated in diabetic wild-type but not in grem1(+/-) kidneys. Levels of pSmad1/5/8 decreased in wild-type but not in grem1(+/-) diabetic kidneys, suggesting that bone morphogenetic protein signaling may be maintained in the absence of grem1. CONCLUSIONS These data identify grem1 as a potential modifier of renal injury in the context of diabetic kidney disease.
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Affiliation(s)
- Sarah A. Roxburgh
- University College Dublin Diabetes Research Centre, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Jayesh J. Kattla
- University College Dublin Diabetes Research Centre, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Simon P. Curran
- University College Dublin Diabetes Research Centre, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Yvonne M. O'Meara
- University College Dublin Diabetes Research Centre, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
- Mater Misericordiae University Hospital, University College Dublin Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Carol A. Pollock
- Kolling Institute, University of Sydney, New South Wales, Australia
| | - Roel Goldschmeding
- Department of Pathology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Catherine Godson
- University College Dublin Diabetes Research Centre, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Finian Martin
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Derek P. Brazil
- University College Dublin Diabetes Research Centre, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
- Corresponding author: Derek P. Brazil,
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Nakano D, Nishiyama A, Kiyomoto H. EFFICACY OF GENE THERAPY FOR TRANSFORMING GROWTH FACTOR-β IN PROGRESSIVE DIABETIC NEPHROPATHY. Clin Exp Pharmacol Physiol 2008; 35:1275-6. [DOI: 10.1111/j.1440-1681.2008.05039.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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11
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Song CY, Kim BC, Lee HS. Lovastatin inhibits oxidized low-density lipoprotein-induced plasminogen activator inhibitor and transforming growth factor-beta1 expression via a decrease in Ras/extracellular signal-regulated kinase activity in mesangial cells. Transl Res 2008; 151:27-35. [PMID: 18061125 DOI: 10.1016/j.trsl.2007.09.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Revised: 09/26/2007] [Accepted: 09/27/2007] [Indexed: 11/29/2022]
Abstract
Oxidized low-density lipoprotein (Ox-LDL) might be involved in the progression of renal disease. Ox-LDL stimulation of plasminogen activator inhibitor-1 (PAI-1) expression via transforming growth factor-beta (TGF-beta)/Smad signaling in mesangial cells required activation of extracellular signal-regulated kinase (ERK). Mevalonate depletion by 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, or statins, decreases the levels of farnesyl pyrophosphate (FPP) for isoprenylation of Ras. We postulate that statins may ameliorate the Ox-LDL-induced mesangial matrix accumulation by inhibiting Ras/ERK activation with subsequent downregulation of TGF-beta target genes. Quiescent mesangial cells were incubated for 18 h with and without the presence of lovastatin before 50 microg/mL of Ox-LDL treatment for 1 h. Lovastatin inhibited markedly the stimulatory effects of Ox-LDL on ERK1/2 activation, nuclear Smad3 expression, TGF-beta1 and PAI-1 mRNA and protein expression, and PAI-1 luciferase activity. These inhibitory effects of lovastatin were reversed almost completely by mevalonate or FPP. Similar to lovastatin, FTI-277, which is an inhibitor of Ras farnesylation, decreased the Ox-LDL-induced activation of ERK/Smad3 and induction of TGF-beta1/PAI-1. These results indicate that lovastatin prevents the Ox-LDL-induced Ras/ERK activation that results in inhibition of Smad3 activation in mesangial cells with subsequent downregulation of TGF-beta target genes. Thus, statins seem to have antifibrotic effects through their anti-TGF-beta response that are relevant in the treatment of chronic renal disease with dyslipidemia.
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Affiliation(s)
- Chi Young Song
- Department of Pathology, Seoul National University College of Medicine, Chongno-gu, Yongon-dong 28, Seoul, Korea
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12
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Raptor-rictor axis in TGFbeta-induced protein synthesis. Cell Signal 2007; 20:409-23. [PMID: 18068336 DOI: 10.1016/j.cellsig.2007.10.027] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Accepted: 10/30/2007] [Indexed: 11/23/2022]
Abstract
Transforming growth factor-beta (TGFbeta) stimulates pathological renal cell hypertrophy for which increased protein synthesis is critical. The mechanism of TGFbeta-induced protein synthesis is not known, but PI 3 kinase-dependent Akt kinase activity is necessary. We investigated the contribution of downstream effectors of Akt in TGFbeta-stimulated protein synthesis. TGFbeta increased inactivating phosphorylation of Akt substrate tuberin in a PI 3 kinase/Akt dependent manner, resulting in activation of mTOR kinase. mTOR activity increased phosphorylation of S6 kinase and the translation repressor 4EBP-1, which were sensitive to inhibition of both PI 3 kinase and Akt. mTOR inhibitor rapamycin and a dominant negative mutant of mTOR suppressed TGFbeta-induced phosphorylation of S6 kinase and 4EBP-1. PI 3 kinase/Akt and mTOR regulated dissociation of 4EBP-1 from eIF4E to make the latter available for binding to eIF4G. mTOR and 4EBP-1 modulated TGFbeta-induced protein synthesis. mTOR is present in two multi protein complexes, mTORC1 and mTORC2. Raptor and rictor are part of mTORC1 and mTORC2, respectively. shRNA-mediated downregulation of raptor inhibited TGFbeta-stimulated mTOR kinase activity, resulting in inhibition of phosphorylation of S6 kinase and 4EBP-1. Raptor shRNA also prevented protein synthesis in response to TGFbeta. Downregulation of rictor inhibited serine 473 phosphorylation of Akt without any effect on phosphorylation of its substrate, tuberin. Furthermore, rictor shRNA increased phosphorylation of S6 kinase and 4EBP-1 in TGFbeta-independent manner, resulting in increased protein synthesis. Thus mTORC1 function is essential for TGFbeta-induced protein synthesis. Our data also provide novel evidence that rictor negatively regulates TORC1 activity to control basal protein synthesis, thus conferring tight control on cellular hypertrophy.
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Dixon A, Maric C. 17beta-Estradiol attenuates diabetic kidney disease by regulating extracellular matrix and transforming growth factor-beta protein expression and signaling. Am J Physiol Renal Physiol 2007; 293:F1678-90. [PMID: 17686959 PMCID: PMC3179625 DOI: 10.1152/ajprenal.00079.2007] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We previously showed that supplementation with 17beta-estradiol (E2) from the onset of diabetes attenuates the development of diabetic renal disease. The aim of the present study was to examine whether E2 can also attenuate the disease process once it has developed. The present study was performed in nondiabetic and streptozotocin-induced diabetic Sprague-Dawley rats. E2 supplementation began after 9 wk of diabetes and continued for 8 wk. Diabetes was associated with an increase in urine albumin excretion, glomerulosclerosis, tubulointerstitial fibrosis, renal cortical collagen type I and IV, laminin, plasminogen activator inhibitor-1, tissue inhibitors of metalloproteinase-1 and -2, transforming growth factor (TGF)-beta, TGF-beta receptor type I and II, Smad2/3, phosphorylated Smad2/3, and Smad4 protein expression, and CD68-positive cell abundance. Decreases in matrix metalloproteinase (MMP)-2 protein expression and activity and decreases in Smad6 and Smad7 protein expression were also associated with diabetes. E2 supplementation completely or partially attenuated all these changes, except Smad4 and fibronectin, on which E2 supplementation had no effect. These data suggest that E2 attenuates the progression of diabetic renal disease once it has developed by regulating extracellular matrix, TGF-beta, and expression of its downstream regulatory proteins. These findings support the notion that sex hormones in general, and E2 in particular, are important regulators of renal function and may be novel targets for the treatment and prevention of diabetic renal disease.
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Affiliation(s)
- Alexis Dixon
- Department of Medicine, Georgetown University Medical Center, Washington, DC 20057
| | - Christine Maric
- Department of Medicine, Georgetown University Medical Center, Washington, DC 20057
- Center for the Study of Sex Differences: in Health, Aging and Disease, Georgetown University Medical Center, Washington, DC 20057
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14
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Song CY, Kim BC, Hong HK, Lee HS. TGF-beta type II receptor deficiency prevents renal injury via decrease in ERK activity in crescentic glomerulonephritis. Kidney Int 2007; 71:882-8. [PMID: 17299519 DOI: 10.1038/sj.ki.5002149] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The role of transforming growth factor-beta (TGF-beta) receptor complex in the pathogenesis of crescentic glomerulonephritis (GN) is not clear. To test the hypothesis that TGF-beta signaling plays a crucial role in the development and progression of crescentic GN by inducing the activation of extracellular signal-regulated kinase (ERK) and expression of its target genes, anti-glomerular basement membrane (GBM) GN was induced in TGF-beta type II receptor (TGF-betaIIR) gene heterozygous (TGF-betaIIR(+/-)) C57BL/6J mice and wild-type animals. GN was initiated in preimmunized mice by administration of rabbit anti-mouse GBM serum. TGF-betaIIR deficiency was significantly associated with decreased renal damage at days 14, 21, and 28 after induction of GN: renal function impairment, proteinuria, proportion of crescents, glomerular accumulation of periodic acid-Schiff-positive material, relative cortical interstitial volume, as well as renal cortical phosphorylation of ERK and plasminogen activator inhibitor type I (PAI-1) and alpha2(I) collagen mRNA levels were significantly decreased in TGF-betaIIR(+/-) mice compared with wild-type animals. These results provide the first direct evidence that TGF-betaIIR deficiency protects against renal injury in crescentic GN, possibly by inhibiting the sustained activation of ERK and PAI-1 and alpha2(I) collagen gene expression. Thus, TGF-beta signaling appears to play an important role in the development and progression of crescentic GN by inducing the ERK activity, and PAI-1 and alpha2(I) mRNA expression.
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Affiliation(s)
- C Y Song
- Department of Pathology, Seoul National University College of Medicine, Chongno-gu, Seoul, Korea
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15
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Russo LM, del Re E, Brown D, Lin HY. Evidence for a role of transforming growth factor (TGF)-beta1 in the induction of postglomerular albuminuria in diabetic nephropathy: amelioration by soluble TGF-beta type II receptor. Diabetes 2007; 56:380-8. [PMID: 17259382 DOI: 10.2337/db06-1018] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Transforming growth factor-beta (TGF-beta) has previously been implicated in the progression of diabetic nephropathy, including the onset of fibrosis and albuminuria. Here we report for the first time the use of a high-affinity TGF-beta1 binding molecule, the soluble human TGF-beta type II receptor (sTbetaRII.Fc), in the treatment of diabetic nephropathy in 12-week streptozotocin-induced diabetic Sprague-Dawley rats. In vitro studies using immortalized rat proximal tubule cells revealed that 50 pmol/l TGF-beta1 disrupted albumin uptake (P < 0.001 vs. control), an inhibition significantly reversed by the use of the sTbetaRII.Fc (1,200 pmol/l). In vivo studies demonstrated that treatment with sTbetaRII.Fc reduced urinary albumin excretion by 36% at 4 weeks, 59% at 8 weeks (P < 0.001), and 45% at 12 weeks (P < 0.01 for diabetic vs. treated). This was correlated with an increase in megalin expression (P < 0.05 for diabetic vs. treated) and a reduction in collagen IV expression following sTbetaRII.Fc treatment (P < 0.001 for diabetic vs. treated). These changes occurred independently of changes in blood glucose levels. This study demonstrates that the sTbetaRII.Fc is a potential new agent for the treatment of fibrosis and albuminuria in diabetic nephropathy and may reduce albuminuria by reducing TGF-beta1-induced disruptions of renal proximal tubule cell uptake of albumin.
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Affiliation(s)
- Leileata M Russo
- Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital/Harvard Medical School, Simches Research Center, 185 Cambridge Street, Boston, MA 02114, USA.
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16
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Chuang TD, Guh JY, Chiou SJ, Chen HC, Hung WC, Chuang LY. Sp1 and Smad3 are required for high glucose-induced p21WAF1 gene transcription in LLC-PK1 cells. J Cell Biochem 2007; 102:1190-201. [PMID: 17516505 DOI: 10.1002/jcb.21346] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The cyclin-dependent kinase inhibitor p21(WAF1) is required for diabetic glomerular hypertrophy. High glucose-induced hypertrophy in proximal tubule cells is dependent on transforming growth factor-beta (TGF-beta). Many of the TGF-beta-induced effects are dependent on Smad2/3. Thus, the molecular mechanisms of high glucose-induced p21(WAF1) and hypertrophy were studied in high glucose-cultured proximal tubule-like LLC-PK(1) cells. We found that high glucose (30 mM) induced hypertrophy at 72 h. High glucose also increased the expression of p21(WAF1) protein and p21(WAF1) mRNA transcription and abundance at 48 h. The DNA element in the 5' regulatory region of p21(WAF1) gene essential for high glucose-induced p21(WAF1) gene transcription was identified as Sp1 by a series of the 5' regulatory region of p21(WAF1) gene deletion mutants. Moreover, high glucose activated Smad2/3 while increasing the Sp1 DNA-binding activity. High glucose also increased the Sp1-dependent transcriptional activity of p21(WAF1) gene. High glucose-induced hypertrophy was attenuated by p21(WAF1) short interfering RNA and Smad3 dominant-negative plasmid transfection. We concluded that high glucose induced hypertrophy via Sp1-Smad2/3-dependent activation of p21(WAF1) gene transcription in LLC-PK(1) cells.
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Affiliation(s)
- Tsai-Der Chuang
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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17
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Lang F, Böhmer C, Palmada M, Seebohm G, Strutz-Seebohm N, Vallon V. (Patho)physiological significance of the serum- and glucocorticoid-inducible kinase isoforms. Physiol Rev 2006; 86:1151-78. [PMID: 17015487 DOI: 10.1152/physrev.00050.2005] [Citation(s) in RCA: 515] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The serum- and glucocorticoid-inducible kinase-1 (SGK1) is ubiquitously expressed and under genomic control by cell stress (including cell shrinkage) and hormones (including gluco- and mineralocorticoids). Similar to its isoforms SGK2 and SGK3, SGK1 is activated by insulin and growth factors via phosphatidylinositol 3-kinase and the 3-phosphoinositide-dependent kinase PDK1. SGKs activate ion channels (e.g., ENaC, TRPV5, ROMK, Kv1.3, KCNE1/KCNQ1, GluR1, GluR6), carriers (e.g., NHE3, GLUT1, SGLT1, EAAT1-5), and the Na+-K+-ATPase. They regulate the activity of enzymes (e.g., glycogen synthase kinase-3, ubiquitin ligase Nedd4-2, phosphomannose mutase-2) and transcription factors (e.g., forkhead transcription factor FKHRL1, beta-catenin, nuclear factor kappaB). SGKs participate in the regulation of transport, hormone release, neuroexcitability, cell proliferation, and apoptosis. SGK1 contributes to Na+ retention and K+ elimination of the kidney, mineralocorticoid stimulation of salt appetite, glucocorticoid stimulation of intestinal Na+/H+ exchanger and nutrient transport, insulin-dependent salt sensitivity of blood pressure and salt sensitivity of peripheral glucose uptake, memory consolidation, and cardiac repolarization. A common ( approximately 5% prevalence) SGK1 gene variant is associated with increased blood pressure and body weight. SGK1 may thus contribute to metabolic syndrome. SGK1 may further participate in tumor growth, neurodegeneration, fibrosing disease, and the sequelae of ischemia. SGK3 is required for adequate hair growth and maintenance of intestinal nutrient transport and influences locomotive behavior. In conclusion, the SGKs cover a wide variety of physiological functions and may play an active role in a multitude of pathophysiological conditions. There is little doubt that further targets will be identified that are modulated by the SGK isoforms and that further SGK-dependent in vivo physiological functions and pathophysiological conditions will be defined.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tuebingen, Tuebingen, Germany.
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18
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Mahimainathan L, Das F, Venkatesan B, Choudhury GG. Mesangial cell hypertrophy by high glucose is mediated by downregulation of the tumor suppressor PTEN. Diabetes 2006; 55:2115-25. [PMID: 16804083 DOI: 10.2337/db05-1326] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Diabetic nephropathy is characterized early in its course by glomerular hypertrophy and, importantly, mesangial hypertrophy, which correlate with eventual glomerulosclerosis. The mechanism of hypertrophy, however, is not known. Gene disruption of the tumor suppressor PTEN, a negative regulator of the phosphatidylinositol 3-kinase/Akt pathway, in fruit flies and mice demonstrated its role in size control in a cell-specific manner. Here, we investigated the mechanism of mesangial hypertrophy in response to high extracellular glucose. We link early renal hypertrophy with significant reduction in PTEN expression in the streptozotocin-induced diabetic kidney cortex and glomeruli, concomitant with activation of Akt. Similarly, exposure of mesangial cells to high concentrations of glucose also decreased PTEN expression and its phosphatase activity, resulting in increased Akt activity. Expression of PTEN inhibited high-glucose-induced mesangial cell hypertrophy, and expression of dominant-negative PTEN was sufficient to induce hypertrophy. In diabetic nephropathy, the hypertrophic effect of hyperglycemia is thought to be mediated by transforming growth factor-beta (TGF-beta). TGF-beta significantly reduced PTEN expression in mesangial cells, with a reduction in its phosphatase activity and an increase in Akt activation. PTEN and dominant-negative Akt attenuated TGF-beta-induced hypertrophy of mesangial cells. Finally, we show that inhibition of TGF-beta signal transduction blocks the effect of high glucose on PTEN downregulation. These data identify a novel mechanism placing PTEN as a key regulator of diabetic mesangial hypertrophy involving TGF-beta signaling.
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Affiliation(s)
- Lenin Mahimainathan
- Department of Medicine, Mail Code 7882, 7703 Floyd Curl Dr., San Antonio, Texas 78229-3900, USA
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19
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Ewens KG, George RA, Sharma K, Ziyadeh FN, Spielman RS. Assessment of 115 candidate genes for diabetic nephropathy by transmission/disequilibrium test. Diabetes 2005; 54:3305-18. [PMID: 16249459 DOI: 10.2337/diabetes.54.11.3305] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Several lines of evidence, including familial aggregation, suggest that allelic variation contributes to risk of diabetic nephropathy. To assess the evidence for specific susceptibility genes, we used the transmission/disequilibrium test (TDT) to analyze 115 candidate genes for linkage and association with diabetic nephropathy. A comprehensive survey of this sort has not been undertaken before. Single nucleotide polymorphisms and simple tandem repeat polymorphisms located within 10 kb of the candidate genes were genotyped in a total of 72 type 1 diabetic families of European descent. All families had at least one offspring with diabetes and end-stage renal disease or proteinuria. As a consequence of the large number of statistical tests and modest P values, findings for some genes may be false-positives. Furthermore, the small sample size resulted in limited power, so the effects of some tested genes may not be detectable, even if they contribute to susceptibility. Nevertheless, nominally significant TDT results (P < 0.05) were obtained with polymorphisms in 20 genes, including 12 that have not been studied previously: aquaporin 1; B-cell leukemia/lymphoma 2 (bcl-2) proto-oncogene; catalase; glutathione peroxidase 1; IGF1; laminin alpha 4; laminin, gamma 1; SMAD, mothers against DPP homolog 3; transforming growth factor, beta receptor II; transforming growth factor, beta receptor III; tissue inhibitor of metalloproteinase 3; and upstream transcription factor 1. In addition, our results provide modest support for a number of candidate genes previously studied by others.
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Affiliation(s)
- Kathryn Gogolin Ewens
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6145, USA
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