401
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Kanwar YS, Wada J, Sun L, Xie P, Wallner EI, Chen S, Chugh S, Danesh FR. Diabetic nephropathy: mechanisms of renal disease progression. Exp Biol Med (Maywood) 2008; 233:4-11. [PMID: 18156300 DOI: 10.3181/0705-mr-134] [Citation(s) in RCA: 426] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Diabetic nephropathy is characterized by excessive amassing of extracellular matrix (ECM) with thickening of glomerular and tubular basement membranes and increased amount of mesangial matrix, which ultimately progress to glomerulosclerosis and tubulo-interstitial fibrosis. In view of this outcome, it would mean that all the kidney cellular elements, i.e., glomerular endothelia, mesangial cells, podocytes, and tubular epithelia, are targets of hyperglycemic injury. Conceivably, high glucose activates various pathways via similar mechanisms in different cell types of the kidney except for minor exceptions that are related to the selective expression of a given molecule in a particular renal compartment. To begin with, there is an obligatory excessive channeling of glucose intermediaries into various metabolic pathways with generation of advanced glycation products (AGEs), activation of protein kinase C (PKC), increased expression of transforming growth factor-beta (TGF-beta), GTP-binding proteins, and generation of reactive oxygen species (ROS). The ROS seem to be the common denominator in various pathways and are central to the pathogenesis of hyperglycemic injury. In addition, there are marked alterations in intraglomerular hemodynamics, i.e., hyperfiltration, and this along with metabolic derangements adversely compounds the hyperglycemia-induced injury. Here, the information compiled under various subtitles of this article is derived from an enormous amount of data summarized in several excellent literature reviews, and thus their further reading is suggested to gain in-depth knowledge of each of the subject matter.
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Affiliation(s)
- Yashpal S Kanwar
- Department of Pathology, Northwestern University School of Medicine, Chicago, IL 60611, USA.
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402
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Wang JJ, Zhang SX, Mott R, Chen Y, Knapp RR, Cao W, Ma JX. Anti-inflammatory effects of pigment epithelium-derived factor in diabetic nephropathy. Am J Physiol Renal Physiol 2008; 294:F1166-73. [PMID: 18322021 DOI: 10.1152/ajprenal.00375.2007] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previously, we have reported that pigment epithelium-derived factor (PEDF) ameliorates albuminuria and inhibits matrix protein deposition in the kidney of streptozotocin (STZ)-induced diabetic rats, suggesting a renoprotective effect of PEDF in early stages of diabetic nephropathy. As inflammation is a major contributor to the development and progression of diabetic nephropathy, we examined in the present study whether PEDF inhibits renal inflammation in diabetic kidney. Diabetic rats received an intravenous injection of an adenovirus expressing PEDF (Ad-PEDF) or the same titer of a control virus. Three wk after the injection, diabetic rats treated with the control virus showed significantly elevated renal levels of proinflammatory factors such as ICAM-1, MCP-1, TNF-alpha, and VEGF compared with age-matched nondiabetic controls. Ad-PEDF effectively suppressed the overexpression of these proinflammatory factors in diabetic kidneys. In cultured primary human renal mesangial cells (HMC), the high-glucose medium-induced upregulation of VEGF and MCP-1 was largely blocked by PEDF. Furthermore, PEDF inhibited high glucose-induced activation of NF-kappaB, a key transcription factor mediating inflammatory responses, and hypoxia-inducible factor-1, a major activator of VEGF expression in HMC. These results suggest that the renoprotective effect of PEDF against diabetic nephropathy may be partially through its anti-inflammatory activity, likely by blocking the NF-kappaB and HIF-1 pathways.
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Affiliation(s)
- Joshua J Wang
- Department of Medicine Endocrinology and Cell Biology, Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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403
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Mishra R, Simonson MS. Oleate Induces a Myofibroblast-Like Phenotype in Mesangial Cells. Arterioscler Thromb Vasc Biol 2008; 28:541-7. [DOI: 10.1161/atvbaha.107.157339] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Rangnath Mishra
- From the Division of Nephrology and Hypertension, Department of Medicine, Case Western Reserve University and University Hospital Case Medical Center, Cleveland Ohio
| | - Michael S. Simonson
- From the Division of Nephrology and Hypertension, Department of Medicine, Case Western Reserve University and University Hospital Case Medical Center, Cleveland Ohio
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404
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Ito H, Fujita H, Takahashi T. Diagnostic biomarkers of diabetic nephropathy. ACTA ACUST UNITED AC 2008; 2:161-9. [DOI: 10.1517/17530059.2.2.161] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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405
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Mishra R, Cool BL, Laderoute KR, Foretz M, Viollet B, Simonson MS. AMP-activated protein kinase inhibits transforming growth factor-beta-induced Smad3-dependent transcription and myofibroblast transdifferentiation. J Biol Chem 2008; 283:10461-9. [PMID: 18250161 DOI: 10.1074/jbc.m800902200] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In wound healing, myofibroblast transdifferentiation (MFT) is a metaplastic change in phenotype producing profibrotic effector cells that secrete and remodel the extracellular matrix. Unlike pathways that induce MFT, the molecular mechanisms that negatively regulate MFT are poorly understood. Here, we report that AMP-activated protein kinase (AMPK) blocks MFT in response to transforming growth factor-beta (TGFbeta). Pharmacological activation of AMPK inhibited TGFbeta-induced secretion of extracellular matrix proteins collagen types I and IV and fibronectin. AMPK activation also prevented induction of the myofibroblast phenotype markers alpha-smooth muscle actin and the ED-A fibronectin splice variant. AMPK activators did not prevent MFT in cells transduced with an adenovirus expressing dominant negative, kinase-dead AMPKalpha2. Moreover, AMPK activators did not inhibit MFT induction in AMPK(alpha1,2)(-/-) fibroblasts, demonstrating a requirement for AMPK(alpha) expression. Adenoviral transduction of constitutively active AMPK(alpha2) was sufficient to prevent TGFbeta-induced collagen I, alpha-smooth muscle actin, and ED-A fibronectin. AMPK did not reduce TGFbeta-stimulated Smad3 COOH-terminal phosphorylation and nuclear translocation, which are necessary for MFT. However, AMPK activation inhibited TGFbeta-induced transcription driven by Smad3-binding cis-elements. Consistent with a role for AMPK in transcriptional regulation, nuclear translocation of AMPKalpha2 correlated with the appearance of active AMPKalpha in the nucleus. Collectively, these results demonstrate that AMPK inhibits TGFbeta-induced transcription downstream of Smad3 COOH-terminal phosphorylation and nuclear translocation. Furthermore, activation of AMPK is sufficient to negatively regulate MFT in vitro.
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Affiliation(s)
- Rangnath Mishra
- Division of Nephrology and Hypertension, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, Ohio 44106, USA
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406
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Davis LK, Rodgers BD, Kelley KM. Angiotensin II- and glucose-stimulated extracellular matrix production: mediation by the insulin-like growth factor (IGF) axis in a murine mesangial cell line. Endocrine 2008; 33:32-9. [PMID: 18392786 PMCID: PMC2684556 DOI: 10.1007/s12020-008-9055-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 01/22/2008] [Accepted: 03/06/2008] [Indexed: 02/05/2023]
Abstract
In diabetic nephropathy, glomerular mesangial cells exhibit aberrant anabolic activity that includes excessive production of extracellular matrix (ECM) proteins, leading to crowding of filtration surface areas and possible renal failure. In the present study, a murine mesangial cell line (MES-13 cells) was studied to determine the roles of the renin-angiotensin system (RAS) and the insulin-like growth factor (IGF) axis in the anabolic response to elevated glucose levels. Culture of MES-13 cells in medium containing supra-physiological glucose concentrations (>5.5 mmol/l) resulted in increased production of ECM proteins including laminin, fibronectin, and heparan sulfate proteoglycan with concurrent increases in IGF-binding protein (IGFBP)-2 production. These responses were blocked by the angiotensin receptor antagonists saralasin and losartan, while exogenous angiotensin II (Ang II) treatment directly stimulated increases in ECM and IGFBP-2. In all experiments, IGFBP-2 levels were correlated with anabolic activity implicating IGFBP-2 as a possible mediator in cellular responses to high glucose and Ang II. Such mediation appears to involve IGFBP-2 modulation of IGF-I signaling, since all responses to high glucose or Ang II were blocked by immuno-neutralization of IGF-I. These data suggest alterations in the IGF axis as key mechanisms underlying nephropathic responses of mesangial cells to Ang II and high glucose.
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Affiliation(s)
- Lori K. Davis
- Endocrinology Laboratory, Department of Biological Sciences, California State University, Long Beach, Long Beach, CA 90840, USA, e-mail:
| | - Buel D. Rodgers
- Department of Animal Sciences, Washington State University, Pullman, WA 99164, USA
| | - Kevin M. Kelley
- Endocrinology Laboratory, Department of Biological Sciences, California State University, Long Beach, Long Beach, CA 90840, USA, e-mail:
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407
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Barski OA, Tipparaju SM, Bhatnagar A. The aldo-keto reductase superfamily and its role in drug metabolism and detoxification. Drug Metab Rev 2008; 40:553-624. [PMID: 18949601 PMCID: PMC2663408 DOI: 10.1080/03602530802431439] [Citation(s) in RCA: 359] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The aldo-keto reductase (AKR) superfamily comprises enzymes that catalyze redox transformations involved in biosynthesis, intermediary metabolism, and detoxification. Substrates of AKRs include glucose, steroids, glycosylation end-products, lipid peroxidation products, and environmental pollutants. These proteins adopt a (beta/alpha)(8) barrel structural motif interrupted by a number of extraneous loops and helixes that vary between proteins and bring structural identity to individual families. The human AKR family differs from the rodent families. Due to their broad substrate specificity, AKRs play an important role in the phase II detoxification of a large number of pharmaceuticals, drugs, and xenobiotics.
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Affiliation(s)
- Oleg A Barski
- Division of Cardiology, Department of Medicine, Institute of Molecular Cardiology, University of Louisville, Louisville, Kentucky 40202, USA.
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408
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Cruzado JM. Nonimmunosuppressive effects of mammalian target of rapamycin inhibitors. Transplant Rev (Orlando) 2008; 22:73-81. [DOI: 10.1016/j.trre.2007.09.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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409
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Sataranatarajan K, Mariappan MM, Lee MJ, Feliers D, Choudhury GG, Barnes JL, Kasinath BS. Regulation of elongation phase of mRNA translation in diabetic nephropathy: amelioration by rapamycin. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1733-42. [PMID: 17991718 DOI: 10.2353/ajpath.2007.070412] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
High glucose and high insulin, pathogenic factors in type 2 diabetes, induce rapid synthesis of the matrix protein laminin-beta1 in renal proximal tubular epithelial cells by stimulation of initiation phase of mRNA translation. We investigated if elongation phase of translation also contributes to high glucose and high insulin induction of laminin-beta1 synthesis in proximal tubular epithelial cells. High glucose or high insulin rapidly increased activating Thr56 dephosphorylation of eEF2 and inactivating Ser366 phosphorylation of eEF2 kinase, events that facilitate elongation. Studies with inhibitors showed that PI3 kinase-Akt-mTOR-p70S6 kinase pathway controlled changes in phosphorylation of eEF2 and eEF2 kinase induced by high glucose or high insulin. Renal cortical homogenates from db/db mice in early stage of type 2 diabetes showed decrease in eEF2 phosphorylation and increment in eEF2 kinase phosphorylation in association with renal hypertrophy and glomerular and tubular increase in laminin-beta1 content. Rapamycin, an inhibitor of mTOR, abolished diabetes-induced changes in phosphorylation of eEF2, eEF2 kinase, and p70S6 kinase and ameliorated renal hypertrophy and laminin-beta1 protein content, without affecting hyperglycemia. These data show that mTOR is an attractive target for amelioration of diabetes-induced renal injury.
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Affiliation(s)
- Kavithalakshmi Sataranatarajan
- O'Brien Kidney Research Center, Department of Medicine, MC 7882, University of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio, TX 78229-3900, USA
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410
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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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411
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Wu D, Peng F, Zhang B, Ingram AJ, Gao B, Krepinsky JC. Collagen I induction by high glucose levels is mediated by epidermal growth factor receptor and phosphoinositide 3-kinase/Akt signalling in mesangial cells. Diabetologia 2007; 50:2008-2018. [PMID: 17622510 DOI: 10.1007/s00125-007-0721-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Accepted: 05/03/2007] [Indexed: 01/18/2023]
Abstract
AIMS/HYPOTHESIS Glomerular matrix accumulation is a hallmark of diabetic nephropathy. Recent data have linked the serine/threonine kinase protein kinase B (Akt) to matrix modulation. Here, we studied its role in high glucose-induced collagen elaboration by mesangial cells. METHODS Primary rat mesangial cells were treated with high glucose levels (30 mmol/l) or mannitol as osmotic control. Western blots, northern blots, ELISA and immunohistochemistry were used for assessment. Diabetes was induced in rats by streptozotocin. RESULTS Phosphorylated Akt at S473 (pAktS473), corresponding to Akt activation, was seen in diabetic glomeruli. In mesangial cells, high glucose levels induced pAktS473 by 20 min. This was sustained to 72 h, while mannitol had no effect. Akt activation by kinase assay and phosphorylation on threonine 308 was also observed. Phosphoinositide 3-kinase (PI3K) inhibitors LY294002 (20 micromol/l) and wortmannin (100 nmol/l) prevented pAktS473. Collagen IA1 transcript and collagen I protein upregulation by high glucose levels were inhibited by PI3K blockade, as was collagen I secretion into the medium (ELISA). Dominant-negative Akt overexpression also inhibited high glucose-induced collagen IA1 transcript and collagen I protein production. Since signalling through the epidermal growth factor receptor (EGFR) can activate PI3K-Akt, we studied its activation by high glucose levels. EGFR was correspondingly activated by 10 min; mannitol had no effect. EGFR activation was also seen in glomeruli from diabetic rats and co-localised with collagen IA1 in diabetic glomeruli. Specific EGFR inhibition (AG1478, 5 micromol/l or dominant-negative EGFR) blocked high glucose-induced pAktS473, phosphorylation on threonine 308 and activation of the EGFR downstream target p44 extracellular signal-regulated kinase (Erk) mitogen-activated protein kinase. Finally, EGFR inhibition also blocked high glucose-induced collagen I upregulation at transcriptional and protein levels. CONCLUSIONS/INTERPRETATION We conclude that EGFR-PI3K-Akt signalling mediates high glucose-induced collagen I upregulation in mesangial cells and that this pathway is activated in diabetic glomeruli. Targeting its components may provide a new therapeutic approach to diabetic kidney disease.
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Affiliation(s)
- D Wu
- Division of Nephrology, McMaster University, Hamilton, ON, Canada
| | - F Peng
- Division of Nephrology, McMaster University, Hamilton, ON, Canada
| | - B Zhang
- Division of Nephrology, McMaster University, Hamilton, ON, Canada
| | - A J Ingram
- Division of Nephrology, McMaster University, Hamilton, ON, Canada
| | - B Gao
- Division of Nephrology, McMaster University, Hamilton, ON, Canada
| | - J C Krepinsky
- Division of Nephrology, McMaster University, Hamilton, ON, Canada.
- McMaster University, St Joseph's Hospital Site, 50 Charlton Ave E, Rm T3311, Hamilton, ON, L8N 4A6, Canada.
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412
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Wahab N, Cox D, Witherden A, Mason RM. Connective tissue growth factor (CTGF) promotes activated mesangial cell survival via up-regulation of mitogen-activated protein kinase phosphatase-1 (MKP-1). Biochem J 2007; 406:131-8. [PMID: 17489738 PMCID: PMC1948989 DOI: 10.1042/bj20061817] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Activated mesangial cells are thought to play a pivotal role in the development of kidney fibrosis under chronic pathological conditions, including DN (diabetic nephropathy). Their prolonged survival may enhance the development of the disease since they express increased amounts of growth factors and extracellular matrix proteins. CTGF (connective tissue growth factor) is one of the growth factors produced by activated mesangial cells and is reported to play a key role in the pathogenesis of DN. Previous studies have shown that addition of exogenous CTGF to HMCs (human mesangial cells) rapidly activates ERK1/2 (extracellular-signal-regulated kinase 1/2) MAPK (mitogen-activated protein kinase) and JNK (c-Jun N-terminal kinase) MAPK, but not the p38 MAPK, despite the activation of the upstream kinases, MKK3/6 (MAPK kinase 3/6). The aim of the present study was to investigate whether the lack of phosphorylated p38 MAPK by CTGF has an anti-apoptotic effect on activated HMCs. We show that in HMC CTGF induces the rapid transcriptional activation and synthesis of MKP-1 (MAPK phosphatase-1), a dual specificity phosphatase that dephosphorylates p38 MAPK. This in turn prevents the anti-apoptotic protein, Bcl-2, from being phosphorylated and losing its function, leading to the survival of the cells. Knockout of MKP-1 protein in mesangial cells treated with CTGF, using siRNA (small interfering RNA) or antisense oligonucleotides, allows p38 MAPK activation and induces mesangial cell death.
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Affiliation(s)
- Nadia Wahab
- Imperial College, Faculty of Medicine, Renal Section, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK.
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413
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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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414
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Li JJ, Kwak SJ, Jung DS, Kim JJ, Yoo TH, Ryu DR, Han SH, Choi HY, Lee JE, Moon SJ, Kim DK, Han DS, Kang SW. Podocyte biology in diabetic nephropathy. Kidney Int 2007:S36-42. [PMID: 17653209 DOI: 10.1038/sj.ki.5002384] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Glomerular visceral epithelial cells, namely podocytes, are highly specialized cells and give rise to primary processes, secondary processes, and finally foot processes. The foot processes of neighboring podocytes interdigitate, leaving between them filtration slits. These are bridged by an extracellular substance, known as the slit diaphragm, which plays a major role in establishing size-selective barrier to protein loss. Furthermore, podocytes are known to synthesize matrix molecules to the glomerular basement membrane (GBM), including type IV collagen, laminin, entactin, and agrin. Because diabetic nephropathy is clinically characterized by proteinuria and pathologically by glomerular hypertrophy and GBM thickening with foot process effacement, podocytes have been the focus in the field of research on diabetic nephropathy. As a result, many investigations have demonstrated that the diabetic milieu per se, hemodynamic changes, and local growth factors such as transforming growth factor-beta and angiotensin II, which are considered mediators in the pathogenesis of diabetic nephropathy, induce directly and/or indirectly hypertrophy, apoptosis, and structural changes, and increase type IV collagen synthesis in podocytes. This review explores some of the structural and functional changes of podocytes under diabetic conditions and their role in the development and progression of diabetic nephropathy.
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Affiliation(s)
- J J Li
- Department of Internal Medicine, Nephrology and Dialysis Unit, The Affiliated Hospital, YanBian University Medical College, JiLin, China
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415
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Pysher MD, Sollome JJ, Regan S, Cardinal TR, Hoying JB, Brooks HL, Vaillancourt RR. Increased hexokinase II expression in the renal glomerulus of mice in response to arsenic. Toxicol Appl Pharmacol 2007; 224:39-48. [PMID: 17643460 PMCID: PMC2042004 DOI: 10.1016/j.taap.2007.06.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 06/12/2007] [Accepted: 06/19/2007] [Indexed: 12/13/2022]
Abstract
Epidemiological studies link arsenic exposure to increased risks of cancers of the skin, kidney, lung, bladder and liver. Additionally, a variety of non-cancerous conditions such as diabetes mellitus, hypertension, and cardiovascular disease have been associated with chronic ingestion of low levels of arsenic. However, the biological and molecular mechanisms by which arsenic exerts its effects remain elusive. Here we report increased renal hexokinase II (HKII) expression in response to arsenic exposure both in vivo and in vitro. In our model, HKII was up-regulated in the renal glomeruli of mice exposed to low levels of arsenic (10 ppb or 50 ppb) via their drinking water for up to 21 days. Additionally, a similar effect was observed in cultured renal mesangial cells exposed to arsenic. This correlation between our in vivo and in vitro data provides further evidence for a direct link between altered renal HKII expression and arsenic exposure. Thus, our data suggest that alterations in renal HKII expression may be involved in arsenic-induced pathological conditions involving the kidney. More importantly, these results were obtained using environmentally relevant arsenic concentrations.
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Affiliation(s)
- Michele D Pysher
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 E. Mabel Street, Tucson, AZ 85721, USA
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416
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Torffvit O, Eriksson JW, Henricsson M, Sundkvist G, Arnqvist HJ, Blohmé G, Bolinder J, Nyström L, Ostman J, Svensson M. Early changes in glomerular size selectivity in young adults with type 1 diabetes and retinopathy. Results from the Diabetes Incidence Study in Sweden. J Diabetes Complications 2007; 21:246-51. [PMID: 17616355 DOI: 10.1016/j.jdiacomp.2006.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Revised: 01/03/2006] [Accepted: 01/04/2006] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To investigate the relationship between early-onset retinopathy and urinary markers of renal dysfunction. RESEARCH DESIGN AND METHODS The Diabetes Incidence Study in Sweden (DISS) aims to register all new cases of diabetes in young adults (15-34 years). In 1987-1988, 806 patients were reported and later invited to participate in a follow-up study focusing on microvascular complications after approximately 10 years of diabetes. In the present study, 149 patients with type 1 diabetes, completed eye examination, and urine sampling were included. RESULTS The patients with retinopathy (n=58, 39%) had higher HbA(1c) (P<.001) and urinary IgG2/creatinine (P<.05) and IgG2/IgG4 ratios (P<.05). Patients with maculopathy had the highest levels. No significant differences in urinary albumin/creatinine, glycosaminoglycans (GAGs)/creatinine, Tamm-Horsfall protein (THP)/creatinine, and IgG4/creatinine ratios were found. Women had higher urinary albumin/creatinine (P<.01) and urinary IgG2/creatinine ratios (P<.01) than men. CONCLUSIONS Young adults with type 1 diabetes and early-onset retinopathy had higher IgG2/creatinine and IgG2/IgG4 ratios than patients without retinopathy indicating that retinopathy is associated with a change in glomerular size selectivity. This was found in association with normal urinary albumin and THP excretion and may be suspected to reflect early general vascular changes.
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Affiliation(s)
- Ole Torffvit
- Department of Medicine, University Hospital of Lund, Lund University, S-221 85 Lund, Sweden.
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417
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Huang JS, Chuang LY, Guh JY, Huang YJ, Hsu MS. Antioxidants attenuate high glucose-induced hypertrophic growth in renal tubular epithelial cells. Am J Physiol Renal Physiol 2007; 293:F1072-82. [PMID: 17596533 DOI: 10.1152/ajprenal.00020.2007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hyperglycemia-induced oxidative stress is a key mediator of renal tubular hypertrophy in diabetic nephropathy (DN). The molecular mechanisms of antioxidants responsible for inhibition of renal tubular hypertrophy in DN are incompletely characterized. We now aim at verifying the effects of N-acetylcysteine (NAC) and taurine on cellular hypertrophy in renal tubular epithelial cells under high ambient glucose. We found that NAC and taurine treatments significantly attenuated high glucose (HG)-inhibited cellular growth and HG-induced hypertrophy. HG-induced Raf-1, p42/p44 mitogen-activated protein kinase (MAPK), Janus kinase 2 (JAK2), and signal transducer and activator of transcription 1 (STAT1) and STAT3 (but not STAT5) activation was markedly blocked by NAC and taurine. Moreover, NAC and taurine increased cyclin D1/cdk4 activation and suppressed p21(Waf1/Cip1) and p27(Kip1) expression in HG-treated cells. It seems that apoptosis was not observed in these treatments. There were no changes in bcl-2 and poly(ADP-ribose) polymerase expression, and mitochondrial cytochrome c release. However, NAC or taurine markedly inhibited the stimulation by HG of fibronectin and type IV collagen protein levels. It is concluded that both NAC and taurine significantly attenuated HG-induced activation of the Raf-1/MAPK and the JAK2-STAT1/STAT3 signaling pathways and hypertrophic growth in renal tubular epithelial cells.
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Affiliation(s)
- Jau-Shyang Huang
- Department of Biological Science and Technology, Chung Hwa University of Medical Technology, Tainan, Taiwan, ROC.
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418
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Lindenmeyer MT, Kretzler M, Boucherot A, Berra S, Yasuda Y, Henger A, Eichinger F, Gaiser S, Schmid H, Rastaldi MP, Schrier RW, Schlöndorff D, Cohen CD. Interstitial vascular rarefaction and reduced VEGF-A expression in human diabetic nephropathy. J Am Soc Nephrol 2007; 18:1765-76. [PMID: 17475821 DOI: 10.1681/asn.2006121304] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Diabetic nephropathy (DN) is a frequent complication in patients with diabetes. Although the majority of DN models and human studies have focused on glomeruli, tubulointerstitial damage is a major feature of DN and an important predictor of renal dysfunction. This study sought to investigate molecular markers of pathogenic pathways in the renal interstitium of patients with DN. Microdissected tubulointerstitial compartments from biopsies with established DN and control kidneys were subjected to expression profiling. Analysis of candidate genes, potentially involved in DN on the basis of common hypotheses, identified 49 genes with significantly altered expression levels in established DN in comparison with controls. In contrast to some rodent models, the growth factors vascular endothelial growth factor A (VEGF-A) and epidermal growth factor (EGF) showed a decrease in mRNA expression in DN. This was validated on an independent cohort of patients with DN by real-time reverse transcriptase-PCR. Immunohistochemical staining for VEGF-A and EGF also showed a reduced expression in DN. The decrease of renal VEGF-A expression was associated with a reduction in peritubular capillary densities shown by platelet-endothelial cell adhesion molecule-1/CD31 staining. Furthermore, a significant inverse correlation between VEGF-A and proteinuria, as well as EGF and proteinuria, and a positive correlation between VEGF-A and hypoxia-inducible factor-1alpha mRNA was found. Thus, in human DN, a decrease of VEGF-A, rather than the reported increase as described in some rodent models, may contribute to the progressive disease. These findings and the questions about rodent models in DN raise a note of caution regarding the proposal to inhibit VEGF-A to prevent progression of DN.
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Affiliation(s)
- Maja T Lindenmeyer
- Nephrologisches Zentrum, Medizinische Poliklinik, University of Munich, Pettenkoferstrasse 8a, 80336 Munich, Germany
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419
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Malik AN, Rossios C, Al-Kafaji G, Shah A, Page RA. Glucose regulation of CDK7, a putative thiol related gene, in experimental diabetic nephropathy. Biochem Biophys Res Commun 2007; 357:237-44. [PMID: 17416350 DOI: 10.1016/j.bbrc.2007.03.132] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2007] [Accepted: 03/22/2007] [Indexed: 10/23/2022]
Abstract
We previously described the identification of the 3'end of an unknown gene CDK7 using differential display which appeared to be up-regulated in diabetic kidneys [R.A. Page, C.A. Morris, J.D. Williams, C.J. von Ruhland, A.N. Malik, Isolation of diabetes-associated kidney genes using differential display, Biochem. Biophys. Res. Commun. 232 (1997) 49-53]. Here we show that CDK7 is a putative thiol related gene which is regulated by glucose in human and rat renal cells. CDK7 mRNA increased by >threefold in cultured human mesangial cells grown in high glucose for 4 days. In the kidneys of the GK rat, a model of type II diabetes, CDK7 showed a steady age-related increase in mRNA, increasing to >sixfold in 40 week GK rats compared to normoglycemic age-matched Wistar rat kidneys, this increase correlates with progressive hyperglycemia. CDK7 mRNA is widely expressed, showing particularly high levels of expression in rat and human liver, and encodes a putative 338 amino acids highly conserved peptide with several conserved domains, including a cys-pro-arg-cys domain conserved in 15 diverse species which is similar to the catalytic centre of thioredoxin, suggesting a role in oxidative stress.
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Affiliation(s)
- Afshan N Malik
- Division of Reproduction and Endocrinology, School of Biomedical and Health Sciences, King's College London, UK.
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420
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Liu Y, Wang Z, Yin W, Li Q, Cai M, Zhang C, Xiao J, Hou H, Li H, Zu X. Severe insulin resistance and moderate glomerulosclerosis in a minipig model induced by high-fat/ high-sucrose/ high-cholesterol diet. Exp Anim 2007; 56:11-20. [PMID: 17283886 DOI: 10.1538/expanim.56.11] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
To develop a minipig model of type 2 diabetes that simulates the common manifestations of the metabolic abnormalities and resembles the kidney pathology of type 2 diabetes in the human population, male Chinese Bama minipigs were divided into 2 groups (5 in each) and fed with a control diet (CD) or high-fat/ high-sucrose/ high-cholesterol diet (HFSCD) for 5 months. The biochemical parameters of blood and urine, and the oral glucose tolerance test were monitored after the feeding program. The insulin resistance was estimated by the HOMA-IR index and the glucose elimination constant (K(G)), and beta-cell function by the HOMA-beta index and the acute insulin response (AIR). Glomerulosclerosis index (GSI) was semi-quantitated by the degree of glomerular lesions in kidney sections stained with Masson trichrome. Extracellular matrix deposition in the kidney was examined by the protein expression of type IV collagen, connective tissue growth factor (CTGF) and matrix metalloproteinases 2 (MMP-2) using immunohistochemistry. Feeding HFSCD to minipigs markedly caused hyperglycaemia, hyperinsulinaemia and dyslipidaemia. HOMA-IR was significantly increased while HOMA-beta, AIR and K(G) were obviously decreased in the HFSCD group compared with control group. Microalbuminuria, glucosuria and moderate glomerulosclerosis were exhibited in HFSCD-fed minipigs. The expression of type IV collagen and CTGF was elevated whereas that of MMP-2 was reduced in the kidneys of HFSCD group compared with the CD group. We concluded that feeding HFSCD to Chinese Bama minipigs for 5 months can induce humanoid type 2 diabetes and early-stage diabetic nephropathy, and accelerate extracellular matrix deposition and glomerulosclerosis.
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Affiliation(s)
- Yi Liu
- Institute of Cardiovascular Research, School of Life Sciences and Technology, Nanhua University, Hengyang, Hunan 421001, PR China
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421
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Abstract
The cause of renal fibrosis in diabetic nephropathy is widely believed to be phenotypic switching of fibroblasts to an activated state. However, emerging evidence suggests that diabetes also alters the phenotype of normal, non-fibroblast kidney cells, such as mesangial cells, tubular epithelial cells, and bone marrow-derived progenitors. Experiments have shown that cytokines, high glucose, and advanced glycation end products induce profibrotic changes in kidney cell phenotype by the processes of myofibroblast transdifferentiation and epithelial-mesenchymal transition. As a result, differentiated kidney cells become reprogrammed to secrete and accumulate extracellular matrix. This revised view implies that inhibiting phenotypic transitions in nonfibroblasts might limit fibrosis in diabetic nephropathy.
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Affiliation(s)
- M S Simonson
- Division of Nephrology and Hypertension, Department of Medicine, School of Medicine, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio 44106, USA.
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422
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Alsaad KO, Herzenberg AM. Distinguishing diabetic nephropathy from other causes of glomerulosclerosis: an update. J Clin Pathol 2007; 60:18-26. [PMID: 17213346 PMCID: PMC1860608 DOI: 10.1136/jcp.2005.035592] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Diabetic nephropathy is a common cause of end-stage renal disease worldwide. It is characterised by diffuse or nodular glomerulosclerosis, afferent and efferent hyaline arteriolosclerosis, and tubulointerstitial fibrosis and atrophy. Diffuse and nodular diabetic glomerulosclerosis share similar histological features with other clinical conditions. Immunofluorescence and electron microscopy studies, and clinicopathological correlation are essential to differentiate diabetic nephropathy from other conditions that result in diffuse and nodular glomerulosclerosis.
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Affiliation(s)
- K O Alsaad
- Department of Laboratory Medicine and Pathobiology, University of Toronto, University Health Network, Toronto, Ontario, Canada
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423
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Hartner A, Cordasic N, Klanke B, Wittmann M, Veelken R, Hilgers KF. Renal injury in streptozotocin-diabetic Ren2-transgenic rats is mainly dependent on hypertension, not on diabetes. Am J Physiol Renal Physiol 2007; 292:F820-7. [PMID: 17018847 DOI: 10.1152/ajprenal.00088.2006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Induction of streptozotocin (STZ) diabetes in hypertensive rats transgenic for the mouse ren-2 gene (TGR) has been described as a model of progressive diabetic nephropathy. We investigated the long-term course of STZ diabetes in TGR and appropriate Sprague-Dawley control rats (SD) and tested the role of angiotensin-dependent hypertension by treating rats with the angiotensin II type 1 receptor blocker losartan (1 mg·kg−1·day−1) via osmotic minipumps. Five weeks after STZ injection, diabetes developed in TGR and SD. Urinary albumin excretion was increased by diabetes and, to a much higher degree, by hypertension. The effects of hypertension and diabetes were not additive, and only the effects of hypertension were ameliorated by losartan. A similar pattern was observed for cell proliferation and macrophage infiltration in the kidney. In contrast, the effects of hypertension and diabetes on glomerular collagen IV accumulation were additive 5 wk after STZ injection. In a long-term study for 20 wk after STZ, survival was better in STZ-treated TGR than in normoglycemic TGR, whereas all SD survived. Impaired creatinine clearance and increased macrophage infiltration as well as glomerular and interstitial matrix deposition were prominent in TGR compared with SD, regardless of the presence or absence of diabetes. In conclusion, STZ diabetes in TGR may be useful to study glomerular and interstitial matrix deposition early in the course of diabetes. However, the long-term course of this animal model resembles severe hypertensive nephrosclerosis, rather than progressive diabetic nephropathy.
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Affiliation(s)
- Andrea Hartner
- Children and Youth Hospital, University of Erlangen-Nuremberg, Erlangen, Germany
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424
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Nakajima T, Hasegawa G, Kamiuchi K, Fukui M, Yamasaki M, Tominaga M, Asano M, Hosoda H, Yoshikawa T, Nakamura N. Differential regulation of intracellular redox state by extracellular matrix proteins in glomerular mesangial cells: potential role in diabetic nephropathy. Redox Rep 2007; 11:223-30. [PMID: 17132271 DOI: 10.1179/135100006x116736] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Advanced diabetic nephropathy is characterized by abnormal synthesis of extracellular matrix (ECM) proteins, such as collagen I (COL I). The present experiments were designed to test the hypothesis that the presence of abnormal ECM proteins may be responsible for increased generation of reactive oxygen species (ROS) that are thought to have an important role in the pathogenesis of diabetic nephropathy. SV40 MES 13 murine mesangial cells were plated on COL I or collagen IV (COL IV) for 3 h at 5.5 or 25 mM D-glucose concentration. Increased intracellular ROS generation and reduced intracellular nitric oxide (NO) production was measured in cells attached to COL I compared with cells attached to COL IV. Treatment with N(omega)-nitro-L-arginine methyl ester hydrochloride (L-NAME), an inhibitor of NO synthase, reduced this difference in ROS generation between cells attached to either COL I or IV. The results using antibodies against integrins also indicated that an alpha(2) integrin-mediated pathway was involved in the different response in ROS generation caused by ECM proteins. These results suggest that contact between altered ECM proteins that are present in advanced diabetic nephropathy and mesangial cells has the potential to increase intracellular oxidative stress, leading to progressive glomerular damage.
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Affiliation(s)
- Toshiki Nakajima
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kamikyo-ku, Kyoto, Japan
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425
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Jung KY, Chen K, Kretzler M, Wu C. TGF-β1 Regulates the PINCH-1–Integrin-Linked Kinase–α-Parvin Complex in Glomerular Cells. J Am Soc Nephrol 2006; 18:66-73. [PMID: 17167118 DOI: 10.1681/asn.2006050421] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Glomerular damage is a major cause of renal failure. Recent studies suggest that a ternary protein complex that consists of PINCH-1, integrin-linked kinase, and alpha-parvin, cytoplasmic components of cell-extracellular matrix adhesions, plays pivotal roles in regulation of glomerular cell behavior. It is reported here that TGF-beta1, a key factor in the progression of glomerular failure, regulates the PINCH-1-integrin-linked kinase-alpha-parvin (PIP) complex formation in glomerular podocytes and mesangial cells. Treatment of podocytes with TGF-beta1 inhibited the PIP complex formation. Forced disruption of the PIP complex in podocytes activated p38 mitogen-activated protein kinase and promoted apoptosis. Importantly, inhibition of p38 mitogen-activated protein kinase, either with a chemical p38 inhibitor (SB202190) or with a dominant negative form of p38alpha, alleviates podocyte apoptosis that is induced by the disruption of the PIP complex. In contrast to an inhibitory role in podocytes, TGF-beta1 promotes the PIP complex formation in mesangial cells. Thus, TGF-beta1 regulates the PIP complex in a cell type-dependent manner. Because the PIP complex promotes glomerular mesangial matrix deposition and protects podocytes from apoptosis, the TGF-beta1-induced up- and downregulation of the PIP complex likely contribute to the pleiotropic effects of TGF-beta1 on different glomerular cell types and hence the progression of glomerular failure.
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Affiliation(s)
- Kyu Yong Jung
- Department of Pathology, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, PA 15261, USA
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426
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Xu H, Zeng L, Peng H, Chen S, Jones J, Chew TL, Sadeghi MM, Kanwar YS, Danesh FR. HMG-CoA reductase inhibitor simvastatin mitigates VEGF-induced “inside-out” signaling to extracellular matrix by preventing RhoA activation. Am J Physiol Renal Physiol 2006; 291:F995-1004. [PMID: 16774905 DOI: 10.1152/ajprenal.00092.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors exert modulatory effects on a number of cell signaling cascades by preventing the synthesis of various isoprenoids derived from the mevalonate pathway. In the present study, we describe a novel pleiotropic effect of HMG-CoA reductase inhibitors, also commonly known as statins, on vascular endothelial growth factor (VEGF)-induced type IV collagen accumulation. VEGF is an angiogenic polypeptide that is also known to play a central role in endothelial cell permeability and differentiation. Recently, VEGF has also been implicated in promoting extracellular matrix (ECM) accumulation, although the precise signaling mechanism that mediates VEGF-induced ECM expansion remains poorly characterized. Elucidation of the mechanisms through which VEGF exerts its effect on ECM is clearly a prerequisite for both understanding the complex biology of this molecule as well as targeting VEGF in several pathological processes. To this end, this study explored the underlying molecular mechanisms mediating VEGF-induced ECM expansion in mesangial cells. Our findings show that VEGF stimulation elicits a robust increase in ECM accumulation that involves RhoA activation, an intact actin cytoskeleton, and β1- integrin activation. Our data also indicate that simvastatin, via mevalonate depletion, reverses VEGF-induced ECM accumulation by preventing RhoA activation.
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Affiliation(s)
- Hanshi Xu
- Feinberg School of Medicine, Northwestern Univ., 303 E. Chicago Ave., Searle Bldg. 10-440, Chicago, IL 60611, USA
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427
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Zhao HJ, Wang S, Cheng H, Zhang MZ, Takahashi T, Fogo AB, Breyer MD, Harris RC. Endothelial nitric oxide synthase deficiency produces accelerated nephropathy in diabetic mice. J Am Soc Nephrol 2006; 17:2664-9. [PMID: 16971655 PMCID: PMC4618687 DOI: 10.1681/asn.2006070798] [Citation(s) in RCA: 268] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Functionally significant polymorphisms in endothelial nitric oxide synthase (eNOS) and reduced vascular eNOS activity have been associated with increased human diabetic nephropathy (DN), but the pathogenic role of eNOS deficiency in the development of DN has not yet been confirmed. This study characterizes the severity of DN in eNOS(-/-) mice that were backcrossed to C57BLKS/J db/db mice. Although the severity of hyperglycemia was similar to C57BLKS/J db/db mice, by 26 wk, eNOS(-/-) C57BLKS/J db/db mice exhibited dramatic albuminuria, arteriolar hyalinosis, increased glomerular basement membrane thickness, mesangial expansion, mesangiolysis, and focal segmental and early nodular glomerulosclerosis. Even more remarkable, eNOS(-/-) C57BLKS db/db exhibited decreases in GFR to levels <50% of that in eNOS(+/+) C57BLKS db/db, as confirmed by increased serum creatinine. In summary, eNOS(-/-) db/db mice provide the most robust model of type II DN that has been described to date and support a role for deficient eNOS-derived NO production in the pathogenesis of DN.
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Affiliation(s)
- Hui John Zhao
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
| | - Suwan Wang
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
| | - Huifang Cheng
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
| | - Ming-zhi Zhang
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
| | - Takamune Takahashi
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
| | - Agnes B. Fogo
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
- Department of Medicine, and Department of Pathology, Vanderbilt University, Nashville, Tennessee
| | - Matthew D. Breyer
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
| | - Raymond C. Harris
- Division of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
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428
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Hsieh CH, Liang KH, Hung YJ, Huang LC, Pei D, Liao YT, Kuo SW, Bey MSJ, Chen JL, Chen EY. Analysis of epistasis for diabetic nephropathy among type 2 diabetic patients. Hum Mol Genet 2006; 15:2701-8. [PMID: 16893912 DOI: 10.1093/hmg/ddl203] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Diabetic nephropathy (DN) is one of the most serious complications of diabetes, accounting for the majority of patients with end-stage renal disease. The molecular pathogenesis of DN involves multiple pathways in a complex, partially resolved manner. The paper presents an exploratory epistatic study for DN. Association analysis were performed on 231 SNP loci in a cohort of 264 type 2 diabetes patients, followed by the epistasis analysis using the multifactor dimensionality reduction and the genetic algorithm with Boolean algebra. A two-locus epistatic effect of EGFR and RXRG was identified, with a cross-validation consistency of 91.7%.
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Affiliation(s)
- Chang-Hsun Hsieh
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Tri-Service General Hospital, Taipei, Taiwan
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429
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Amazonas RB, Lopes de Faria JB. Effects of tight blood pressure control on glomerular hypertrophy in a model of genetic hypertension and experimental diabetes mellitus. Life Sci 2006; 79:2135-43. [PMID: 16890245 DOI: 10.1016/j.lfs.2006.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 06/19/2006] [Accepted: 07/06/2006] [Indexed: 11/17/2022]
Abstract
The aim of this study was to evaluate the effect of prevention of hypertension on glomerular hypertrophy, renal cell replication and accumulation of glomerular fibronectin in a model of genetic hypertension and experimental diabetes. Four-week-old streptozotocin induced spontaneously hypertensive rats (SHR) were randomized for no treatment, or for treatment with captopril, losartan or triple therapy (hydrochlorothiazide, reserpine and hydralazine) for 20 days. Increase in systolic blood pressure was equally prevented by captopril (118+/-15 mmHg), losartan (111+/-9) and triple therapy (112+/-14, p<0.0001). Glomerular size was higher (p<0.005) in diabetic SHR (27,300+/-2130 microm(2)) compared with non-diabetic SHR (23,800+/-307). The antihypertensive therapy with captopril (23,900+/-175), losartan (23,800+/-120), and triple therapy (23,400+/-210) prevented the glomerular enlargement in diabetic SHR. Glomerular expression of fibronectin was increased in diabetic SHR (7.61+/-1.22 densitometric unit) as compared to the controls (2.27+/-2.15, p<0.0001), and was decreased (p<0.0001 vs diabetic SHR) with captopril (2.49+/-1.42), losartan (1.57+/-1.1) and triple therapy (2.04+/-1.42). The number of replicating glomerular cell significantly decreased in diabetic SHR and it was restored by all three antihypertensive regimes. The glomerular expression of p27(Kip1) was increased in diabetic SHR but it was not modified by antihypertensive treatment. Strict blood pressure control, in diabetic SHR independently of the class of antihypertensive agent, restores glomerular hypertrophy and renal cellular replication, and prevents the increment in glomerular fibronectin.
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Affiliation(s)
- Roberto Bleuel Amazonas
- Laboratory of Renal Pathophysiology, Nephrology Unit, State University of Campinas (UNICAMP), Campinas, SP, Brazil
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430
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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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431
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Maezawa Y, Yokote K, Sonezaki K, Fujimoto M, Kobayashi K, Kawamura H, Tokuyama T, Takemoto M, Ueda S, Kuwaki T, Mori S, Wahren J, Saito Y. Influence of C-peptide on early glomerular changes in diabetic mice. Diabetes Metab Res Rev 2006; 22:313-22. [PMID: 16389646 DOI: 10.1002/dmrr.612] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND C-peptide has been shown to ameliorate diabetes-induced functional and structural renal changes in animal models as well as in patients with type 1 diabetes. This study aims to examine the molecular effects of C-peptide on early glomerular changes in a mouse model of type 1 diabetes. METHODS Fourteen days after induction of diabetes by streptozotocin (STZ), the animals received rat C-peptide for either 24 h or 7 days. Urinary albumin excretion was measured by ELISA. Glomerular mRNA expression of the transforming growth factor (TGF)-beta(1) and type IV collagen was quantified by real-time PCR. The effect of C-peptide on type IV collagen gene expression in cultured murine podocytes was also examined. RESULTS C-peptide decreased urinary albumin excretion from 0.29 to 0.18 microg/min (-40.7%, P < 0.01). The transcript level of (alpha3)IV collagen in glomeruli was up-regulated 2.2-fold in diabetic mice and was inhibited by 45-70% (P < 0.05) upon C-peptide treatment. C-peptide suppressed glomerular expression of TGF-beta(1) by 36.6% after 7 days (P < 0.05) but not 24 h after injection. In vitro studies using cultured podocytes revealed that C-peptide dose-dependently inhibited TGF-beta-induced up-regulation of type IV collagen. Moreover, both pertussis toxin (PTX) and a specific inhibitor for extracellular signal-regulated kinase (ERK) pathway reversed the inhibitory effect of C-peptide on TGF-beta. Finally, C-peptide was shown to up-regulate the activity of ERK in podocytes. CONCLUSIONS These findings indicate that C-peptide suppresses specific aspects of early glomerular changes in a mouse model of diabetes and that the effect is at least in part mediated via interaction with the TGF-beta signal in glomerular podocytes.
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Affiliation(s)
- Yoshiro Maezawa
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chiba 260-8670, Japan
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432
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Boucher E, Mayer G, Londono I, Bendayan M. Expression and localization of MT1-MMP and furin in the glomerular wall of short- and long-term diabetic rats. Kidney Int 2006; 69:1570-7. [PMID: 16541018 DOI: 10.1038/sj.ki.5000316] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Diabetic glomerulopathy has been linked to shifts in balance between the synthetic and degradative pathways of the glomerular basement membrane (GBM), a key player in the permselectivity properties of the glomerular wall. The goal of this study was to trace the expression and localization of membrane type-1 metalloprotease (MT1-MMP) and its activating enzyme furin, key proteins involved in basement membrane turnover, in short- and long-term diabetic rat renal tissues. Quantitative immunogold was carried out for MT1-MMP and furin and their expression was evaluated in renal tissues of young and old, control and diabetic rats. To corroborate immunocytochemical findings, Western blots were performed on glomerular lysates. Electron microscopy revealed that the overall expression of MT1-MMP and furin is reduced in plasma membranes of all glomerular cell types of old normoglycemic animals, a phenomenon that is exacerbated in long-term diabetic animals. This observation supports the prevailing theory that diabetes fosters acceleration in the aging process. Interestingly, while biochemical results confirmed a decrease in MT1-MMP expression, an increase in furin was observed. Immunocytochemical studies resolved this discrepancy by tracing the increased furin expression in endoplasmic reticulum and Golgi membranes of podocytes, indicating that furin is retained in the secretory pathway in a diabetic environment. Disturbances at the molecular level of the otherwise tightly regulated MT1-MMP/furin interactions found at the cell surface must account for a lack in extracellular matrix remodeling, increased deposition of GBM material, and loss of glomerular filtration integrity.
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Affiliation(s)
- E Boucher
- Department of Pathology and Cell Biology, University of Montreal, Montreal, Quebec, Canada
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433
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Diabetes and Nephropathy. POINT OF CARE 2006. [DOI: 10.1097/00134384-200606000-00005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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434
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Guo M, Ricardo SD, Deane JA, Shi M, Cullen-McEwen L, Bertram JF. A stereological study of the renal glomerular vasculature in the db/db mouse model of diabetic nephropathy. J Anat 2006; 207:813-21. [PMID: 16367807 PMCID: PMC1571575 DOI: 10.1111/j.1469-7580.2005.00492.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In diabetic nephropathy, glomerular hypertrophy is evident early in response to hyperglycaemia. Alterations of capillary length and vascular remodelling that may contribute to glomerular hypertrophy and the subsequent development of glomerulosclerosis remain unclear. The present study used the db/db mouse model of Type 2 diabetes to examine the glomerular microvascular changes apparent with long-term diabetic complications. Unbiased stereological methods and high-resolution light microscopy were used to estimate glomerular volume, and glomerular capillary dimensions including length and surface area in 7-month-old db/db diabetic mice and age-matched db/m control mice. The db/db diabetic mice showed significant glomerular hypertrophy, corresponding with elevated blood glucose levels, and increased body weight and kidney weight, compared with db/m control mice. Glomerular enlargement in db/db mice was associated with increases in the surface area (5.387 +/- 0.466 x 10(4) microm2 vs. 2.610 +/- 0.287 x 10(4) microm2; P < 0.0005) and length (0.3343 +/- 0.022 x 10(4) microm vs. 0.1549 +/- 0.017 x 10(4) microm; P < 0.0001) of capillaries per glomerulus, compared with non-diabetic mice. Stereological assessment at the electron microscopic level revealed increased glomerular volume density of mesangial cells and mesangial matrix, and thickening of the glomerular basement membrane in db/db mice. These results demonstrate that glomerular hypertrophy evident in advanced diabetic nephropathy in this model is associated with increased length and surface area of glomerular capillaries. The contribution of angiogenesis and vasculogenesis to the glomerular microvascular alterations in response to hyperglycaemia remain to be determined.
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Affiliation(s)
- Min Guo
- Department of Anatomy and Cell Biology, School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
| | - Sharon D Ricardo
- Department of Anatomy and Cell Biology, School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
- Monash Immunology and Stem Cell Laboratories (MISCL), School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
| | - James A Deane
- Department of Anatomy and Cell Biology, School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
- Monash Immunology and Stem Cell Laboratories (MISCL), School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
| | - Ming Shi
- Department of Anatomy and Cell Biology, School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
| | - Luise Cullen-McEwen
- Department of Anatomy and Cell Biology, School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
| | - John F Bertram
- Department of Anatomy and Cell Biology, School of Biomedical Sciences, Monash UniversityClayton, Victoria, Australia
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435
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Lloberas N, Cruzado JM, Franquesa M, Herrero-Fresneda I, Torras J, Alperovich G, Rama I, Vidal A, Grinyó JM. Mammalian Target of Rapamycin Pathway Blockade Slows Progression of Diabetic Kidney Disease in Rats. J Am Soc Nephrol 2006; 17:1395-404. [PMID: 16597691 DOI: 10.1681/asn.2005050549] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Recent data suggest that the phosphatidylinositol 3-kinase (PI3-K)/Akt/mammalian target of rapamycin (mTOR) pathway is important in diabetic nephropathy. The effect of mTOR blockade by sirolimus (SRL) in diabetic kidney disease in rats was investigated. Diabetes was induced by streptozotocin in male Sprague-Dawley rats. Sixteen weeks later, diabetic animals were divided into the following groups: diabetes (D; n = 8), diabetes + SRL at 1 mg/kg per d, SRL trough level 2.3 +/- 0.25 ng/ml (D+SRL; n = 7); and diabetes + normoglycemia maintained by insulin implants (D+NG; n = 5). There was an age-matched nondiabetic group (ND; n = 6). All animals were followed for 4 wk. The D group showed glomerular hypertrophy (mean glomerular volume 5.0 +/- 0.4 in D versus 3.3 +/- 0.2 10(6) mu(3) in ND; P < 0.05) without renal hyperplasia (calculated by reverse transcription-PCR of proliferative cell nuclear antigen) and albuminuria (29 +/- 4 in D versus 1.4 +/- 1.5 mg/24 h in ND; P < 0.05). Both D+NG and D+SRL groups had a significant reduction of albuminuria, although glomerular hypertrophy was still present. SRL treatment did not modify the number of infiltrating renal ED1(+) cells. Diabetic animals had greater expression of p-Akt and mTOR, unlike ND rats. NG and SRL treatment reduced p-Akt and normalized mTOR. It is interesting that D+SRL was associated with a significant reduction of renal TGF-beta1 and glomerular connective tissue growth factor. SRL treatment reduced glomerular alpha-smooth muscle actin overexpression and reduced significantly the mesangial matrix accumulation that is characteristic of diabetic nephropathy. In conclusion, mTOR blockade by low-dose SRL has a beneficial effect in diabetic kidney disease, suggesting that the mTOR pathway has an important pathogenic role in diabetic nephropathy.
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Affiliation(s)
- Núria Lloberas
- Nephrology Service, Hospital Universitari de Bellvitge, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Catalonia, Spain
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436
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Kosugi T, Yuzawa Y, Sato W, Kawai H, Matsuo S, Takei Y, Muramatsu T, Kadomatsu K. Growth factor midkine is involved in the pathogenesis of diabetic nephropathy. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 168:9-19. [PMID: 16400005 PMCID: PMC1592654 DOI: 10.2353/ajpath.2006.050488] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Diabetic nephropathy is a life-threatening disease associated with diabetes mellitus. Longstanding hyperglycemia induces pathological reactions of glomerular mesangial cells, such as overproduction of extracellular matrix, which finally lead to nephropathy. However, the mechanisms underlying its pathogenesis have not been completely elucidated. Using the Streptozotocin-induced model of diabetes, we report that mice deficient in the growth factor midkine (Mdk-/-) exhibited strikingly milder nephropathy than Mdk+/+ mice, even though both mice showed similar extents of hyperglycemia after Streptozotocin injection. Midkine expression was induced in the glomerular mesangium of Mdk+/+ mice with diabetic nephropathy and in primary cultured mesangial cells exposed to high glucose. Mdk-/- mesangial cells exhibited reduced phosphorylation of protein kinase C and extracellular signal-regulated kinase as well as reduced production of transforming growth factor-beta(1) on high glucose loading. Addition of exogenous midkine restored extracellular signal-regulated kinase phosphorylation in Mdk-/- cells under high glucose conditions, whereas a midkine antisense oligodeoxynucleotide suppressed midkine in Mdk+/+ cells. Therefore, this study identifies midkine as a key molecule in diabetic nephropathy and suggests that midkine accelerates the intracellular signaling network evoked by hyperglycemia in nephropathy.
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Affiliation(s)
- Tomoki Kosugi
- Department of Biochemistry, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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437
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Abstract
Clinical diabetic nephropathy is characterized by an earlier functional phase in which hyperglycaemia is accompanied by an increased glomerular filtration rate and microalbuminuria; the persistence of this high-flow and high-pressure state, added to a poor control of hyperglycaemia, fosters renal damage and proteinuria, accompanied by a decline in glomerular filtration rate and progression to end-stage renal disease. In this review, we present glucose transporter 1 (GLUT-1) as a novel link that connects the glomerular hyperfiltration (hypertension) state and the complex cascade of events that leads to nephropathy. The interplay between angiotensin II and nitric oxide, and its interactions with reactive oxygen species, are also discussed, in an attempt to provide an integrated view of the pathophysiology of diabetic nephropathy.
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Affiliation(s)
- Carlos A Leon
- Division of Nephrology and Hypertension, University of Miami School of Medicine, Nephrology-Hypertension Section, Veterans Affairs Medical Center, FL 33125, USA
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438
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Danda RS, Habiba NM, Rincon-Choles H, Bhandari BK, Barnes JL, Abboud HE, Pergola PE. Kidney involvement in a nongenetic rat model of type 2 diabetes. Kidney Int 2006; 68:2562-71. [PMID: 16316331 DOI: 10.1111/j.1523-1755.2005.00727.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Rats fed a high fat diet and given a low dose of streptozotocin (STZ) (35 mg/kg) develop type 2 diabetes with insulin resistance, hyperinsulinemia, moderate hyperglycemia, hyperlipidemia, and salt-sensitive hypertension. We postulated that rats with noninsulinopenic (type 2) diabetes develop lesions of diabetic nephropathy significantly more prominent than those seen in classic insulinopenic (type 1) diabetic rats. METHODS Rats were fed regular chow or high fat diet (60% calories from fat and 70% animal fat). After 5 weeks, rats fed regular chow received vehicle (controls) or 55 mg/kg STZ (type 1 diabetes mellitus). Rats fed high fat diet received vehicle (high fat) or low dose STZ, 35 mg/kg (type 2 diabetes mellitus). Rats were sacrificed 14 weeks after STZ/vehicle injection. RESULTS Blood glucose, systolic blood pressure, and urinary protein excretion were significantly higher in both diabetes groups than in controls. Serum insulin levels (ng/mL) were higher in type 2 diabetes than in type 1 diabetes groups (0.49 +/- 0.12 vs. 0.07 +/- 0.07) (P= 0.01). Percentage of sclerosed glomeruli was significantly higher in type 2 diabetes group than in control and type 1 diabetes groups. Fibronectin expression was significantly increased in high fat, type 1 and type 2 diabetes groups compared to controls. The expression of type IV collagen, connective tissue growth factor (CTGF), and transforming growth factor-beta (TGF-beta) was significantly increased in high fat and type 2 diabetes groups compared to controls. CONCLUSION Rats fed a high fat diet and given a low dose of STZ developed diabetes (with normal/high insulin levels), hypertension, and proteinuria. Kidney lesions in this type 2 model appear to be more pronounced than in type 1 diabetic rats despite lower blood glucose levels and proteinuria. We present a nongenetic rat model of type 2 diabetes mellitus and nephropathy.
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Affiliation(s)
- Ratna S Danda
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
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439
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Asbun J, Villarreal FJ. The pathogenesis of myocardial fibrosis in the setting of diabetic cardiomyopathy. J Am Coll Cardiol 2006; 47:693-700. [PMID: 16487830 DOI: 10.1016/j.jacc.2005.09.050] [Citation(s) in RCA: 344] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 08/24/2005] [Accepted: 09/26/2005] [Indexed: 12/11/2022]
Abstract
Diabetes has emerged as a major threat to worldwide health. The increasing incidence of diabetes in young individuals is particularly worrisome given that the disease is likely to evolve over a period of years. In 1972, the existence of a diabetic cardiomyopathy was proposed based on the experience with four adult diabetic patients who suffered from congestive heart failure in the absence of discernible coronary artery disease, valvular or congenital heart disease, hypertension, or alcoholism. The exact mechanisms underlying the disease are unknown; however, an important component of the pathological alterations observed in these hearts includes the accumulation of extracellular matrix (ECM) proteins, in particular collagens. The excess deposition of ECM in the heart mirrors what occurs in other organs such as the kidney and peritoneum of diabetics. Mechanisms responsible for these alterations may include the excess production, reduced degradation, and/or chemical modification of ECM proteins. These effects may be the result of direct or indirect actions of high glucose concentrations. This article reviews our state of knowledge on the effects that diabetes-like conditions exert on the cells responsible for ECM production as well as relevant experimental and clinical data.
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Affiliation(s)
- Juan Asbun
- Escuela Superior de Medicina del Instituto Politécnico Nacional, Mexico City, Mexico
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440
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Kanwar YS, Akagi S, Nayak B, Sun L, Wada J, Xie P, Thakur A, Chugh SS, Danesh FR. Renal-specific oxidoreductase biphasic expression under high glucose ambience during fetal versus neonatal development. Kidney Int 2005; 68:1670-83. [PMID: 16164644 DOI: 10.1111/j.1523-1755.2005.00611.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Renal-specific oxidoreductase (RSOR) has been recently identified in mice kidneys of diabetic animals, and it is developmentally regulated. Its expression during fetal, neonatal, and postnatal periods was assessed under high glucose ambience. METHODS Whole-mount immunofluorescence and confocal microscopy were performed to assess the effect of high glucose on the morphogenesis of mice fetal kidneys. RSOR mRNA and protein expression was assessed by competitive polymerase chain reaction (PCR) and immunoprecipitation methods in embryonic kidneys (day E13 to E17) subjected to high glucose ambience and by Northern and Western blot analyses of kidneys of newborn and 1-week-old mice with hyperglycemia. The spatiotemporal changes in the RSOR expression were assessed by in situ hybridization analyses and immunofluorescence microscopy. In addition, the extent of apoptosis in the kidneys was determined by terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) assay. RESULTS Whole-mount microscopy of the embryonic metanephroi revealed a dose-dependent disruption in the ureteric bud iterations with reduced population of the nascent nephrons. Both gene and protein expressions were reduced in day E13 to E17 metanephroi, while increased in kidneys of newborn and 1-week-old mice. In day E13 and day E15 kidneys, the RSOR was expressed in the ureteric bud branches and some of the immature tubules, and its expression was reduced with high glucose treatment. In day E17 kidneys the RSOR was expressed in the tubules of the deeper cortex, and its expression was marginally decreased. In newborn kidneys, this enzyme was expressed in the subcortical tubules and it spread to the entire width of the renal cortex in hyperglycemic state. In 1-week-old mice kidneys, the RSOR was localized to the entire cortex, and in animals with blood glucose above 300 mg/dL, its intensity increased with extension of expression into the outer medullary tubules. A dose-dependent fulminant apoptosis was observed in day E13 to E17 kidneys subjected to high glucose ambience. In newborn and 1-week-old mice control kidneys, the apoptosis was minimal although slightly increased during hyperglycemia. CONCLUSION High glucose has a differential effect on the RSOR expression in kidneys during the embryonic versus neonatal/postnatal period. This may partly be related to the differential degree of apoptosis, a process reflective of oxidant stress that is seen in diabetic milieu, which as previously has been shown to adversely effect the modulators of fetal development and thereby the morphogenesis of the kidney and RSOR expression.
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Affiliation(s)
- Yashpal S Kanwar
- Department of Pathology, Northwestern University Medical Center, Chicago, Illinois 60611, USA.
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441
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Roestenberg P, van Nieuwenhoven FA, Joles JA, Trischberger C, Martens PP, Oliver N, Aten J, Höppener JW, Goldschmeding R. Temporal expression profile and distribution pattern indicate a role of connective tissue growth factor (CTGF/CCN-2) in diabetic nephropathy in mice. Am J Physiol Renal Physiol 2005; 290:F1344-54. [PMID: 16380465 DOI: 10.1152/ajprenal.00174.2005] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Connective tissue growth factor (CTGF) is overexpressed in diabetic nephropathy (DN) and has therefore been implicated in its pathogenesis. The objective of the present study was to determine the tissue distribution of increased CTGF expression and the relationship of plasma, urinary, and renal CTGF levels to the development and severity of DN. We studied the relationship between CTGF and renal pathology in streptozotocin (STZ)-induced diabetes in C57BL/6J mice. Diabetic and age-matched control mice were killed after 1, 2, 4, and 9 wk of diabetes. In addition, key parameters of diabetes and DN were analyzed in 10-mo-old diabetic ob/ob mice and their ob/+ littermates. STZ-induced diabetic mice showed a significantly increased urinary albumin excretion after 1 wk and increased mesangial matrix score after 2 wk. Increased renal fibronectin, fibronectin ED-A, and collagen IValpha1 expression, as well as elevated plasma creatinine levels, were observed after 9 wk. After 2 wk, CTGF mRNA was upregulated threefold in the renal cortex. By 9 wk, CTGF mRNA was also increased in the heart and liver. In contrast, transforming growth factor-beta1 mRNA content was significantly increased only in the kidney by 9 wk. Renal CTGF expression was mainly localized in podocytes and parietal glomerular epithelial cells, and less prominent in mesangial cells. In addition, plasma CTGF levels and urinary CTGF excretion were increased in diabetic mice. Moreover, albuminuria strongly correlated with urinary CTGF excretion (R = 0.83, P < 0.0001). Increased CTGF expression was also demonstrated in type 2 diabetic ob/ob mice, which points to a causal relationship between diabetes and CTGF and thus argues against a role of STZ in this process. The observed relationship of podocyte and urinary CTGF to markers of DN suggests a pathogenic role of CTGF in the development of DN.
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Affiliation(s)
- Peggy Roestenberg
- Dept. of Pathology, Univ. Medical Ctr. Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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442
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Nayak B, Xie P, Akagi S, Yang Q, Sun L, Wada J, Thakur A, Danesh FR, Chugh SS, Kanwar YS. Modulation of renal-specific oxidoreductase/myo-inositol oxygenase by high-glucose ambience. Proc Natl Acad Sci U S A 2005; 102:17952-7. [PMID: 16330753 PMCID: PMC1312416 DOI: 10.1073/pnas.0509089102] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Indexed: 12/19/2022] Open
Abstract
Biological properties of renal-specific oxidoreductase (RSOR), characteristics of its promoter, and underlying mechanisms regulating its expression in diabetes were analyzed. RSOR expression, normally confined to the renal cortex, was markedly increased and extended into the outer medullary tubules in db/db mice, a model of type 2 diabetes. Exposure of LLCPK cells to d-glucose resulted in a dose-dependent increase in RSOR expression and its enzymatic activity. The latter was related to one of the glycolytic enzymes, myo-inositol oxygenase. The increase in activity was in proportion to serum glucose concentration. The RSOR expression also increased in cells treated with various organic osmolytes, e.g., sorbitol, myoinositol, and glycerolphosphoryl-choline and H(2)O(2). Basal promoter activity was confined to -1,252 bp upstream of ATG, and it increased with the treatment of high glucose and osmolytes. EMSAs indicated an increased binding activity with osmotic-, carbohydrate-, and oxidant-response elements in cells treated with high glucose and was abolished by competitors. Supershifts, detected by anti-nuclear factor of activated T cells, and carbohydrate-response-element-binding protein established the binding specificity. Nuclear factor of activated T cells tonicity-enhancer-binding protein and carbohydrate-response-element-binding protein had increased nuclear expression in cells treated with high glucose. The activity of osmotic-response element exhibited a unique alternate binding pattern, as yet unreported in osmoregulatory genes. Data indicate that RSOR activity is modulated by diverse mechanisms, and it is endowed with dual properties to channel glucose intermediaries, characteristic of hepatic aldehyde reductases, and to maintain osmoregulation, a function of renal medullary genes, e.g., aldose reductase, in diabetes.
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Affiliation(s)
- Baibaswata Nayak
- Department of Pathology, Northwestern University Medical School, Chicago, IL 60611, USA
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443
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Elberg G, Elberg D, Logan CJ, Chen L, Turman MA. Limitations of Commonly Used Internal Controls for Real-Time RT-PCR Analysis of Renal Epithelial-Mesenchymal Cell Transition. ACTA ACUST UNITED AC 2005; 102:e113-22. [PMID: 16340238 DOI: 10.1159/000090070] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Accepted: 09/14/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Progressive renal fibrotic disease is accompanied by the massive accumulation of myofibroblasts as defined by alpha smooth muscle actin (alphaSMA) expression. We quantitated gene expression using real-time RT-PCR analysis during conversion of primary cultured human renal tubular cells (RTC) to myofibroblasts after treatment with transforming growth factor-beta1 (TGF-beta1). We report herein the limitations of commonly used reference genes for mRNA quantitation. METHODS We determined the expression of alphaSMA and megakaryoblastic leukemia-1 (MKL1), a transcriptional regulator of alphaSMA, by quantitative real-time PCR using three common internal controls, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), cyclophilin A and 18S rRNA. RESULTS Expression of GAPDH mRNA and cyclophilin A mRNA, and to a lesser extent, 18S rRNA levels varied over time in culture and with exposure to TGF-beta1. Thus, depending on which reference gene was used, TGF-beta1 appeared to have different effects on expression of MKL1 and alphaSMA. CONCLUSIONS RTC converting to myofibroblasts in primary culture is a valuable system to study renal fibrosis in humans. However, variability in expression of reference genes with TGF-beta1 treatment illustrates the need to validate mRNA quantitation with multiple reference genes to provide accurate interpretation of fibrosis studies in the absence of a universal internal standard for mRNA expression.
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Affiliation(s)
- Gerard Elberg
- Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
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444
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Wahab NA, Schaefer L, Weston BS, Yiannikouris O, Wright A, Babelova A, Schaefer R, Mason RM. Glomerular expression of thrombospondin-1, transforming growth factor beta and connective tissue growth factor at different stages of diabetic nephropathy and their interdependent roles in mesangial response to diabetic stimuli. Diabetologia 2005; 48:2650-60. [PMID: 16270194 DOI: 10.1007/s00125-005-0006-5] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Accepted: 07/11/2005] [Indexed: 01/17/2023]
Abstract
AIMS/HYPOTHESIS We quantified the glomerular expression of thrombospondin-1 (THBS1, also known as TSP-1), transforming growth factor beta 1 (TGFB1, also known as TGF-beta1) and connective tissue growth factor (CTGF) at each stage of diabetic nephropathy. We also examined the roles of THBS1 and CTGF in mediating high-glucose- and glycated-albumin-induced synthesis of the matrix protein, fibronectin, by mesangial cells. METHODS THBS1, latent and active TGFB1, and CTGF, were detected by immunohistochemistry and in situ hybridisation in biopsies from 19 insulin-dependent diabetic patients with incipient, manifest and advanced diabetic nephropathy, and in 11 control kidneys. Findings were quantified by image analysis. Human mesangial cells were cultured with normal or high glucose, albumin or glycated albumin (Amadori product), +/-THBS1 or CTGF antisense oligonucleotides, or with peptide W, an inhibitor of TGFB1 bioactivation by THBS1. Proteins were measured by western blot analysis or ELISA. RESULTS In glomeruli of normal kidneys, mRNA and protein levels for THBS1, latent-TGFB1 and CTGF were low. They were increased in the incipient stage of diabetic nephropathy, predominantly in mesangial areas, with further increases at later stages of the disease. Little or no active TGFB1 immunostaining was detected prior to manifest diabetic nephropathy. In contrast to high-glucose conditions, increases in fibronectin synthesis that were stimulated by glycated albumin were not dependent on THBS1 activation of latent TGFB1. However, increased fibronectin synthesis in both conditions required CTGF. CONCLUSIONS/INTERPRETATION Increased glomerular expression of all three factors occurs from the earliest stage of diabetic nephropathy. In contrast to THBS1, CTGF is required for mesangial synthesis of fibronectin stimulated by high glucose or glycated albumin, and is thus a potential therapeutic target.
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Affiliation(s)
- N A Wahab
- Cell and Molecular Biology Section, Division of Biomedical Sciences, Imperial College London, London, UK.
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445
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Li Y, Wen X, Spataro BC, Hu K, Dai C, Liu Y. hepatocyte growth factor is a downstream effector that mediates the antifibrotic action of peroxisome proliferator-activated receptor-gamma agonists. J Am Soc Nephrol 2005; 17:54-65. [PMID: 16291834 PMCID: PMC1820837 DOI: 10.1681/asn.2005030257] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a ligand-dependent transcription factor that plays an important role in the regulation of insulin sensitivity and lipid metabolism. Evidence shows that PPAR-gamma agonists also ameliorate renal fibrotic lesions in both diabetic nephropathy and nondiabetic chronic kidney disease. However, little is known about the mechanism underlying their antifibrotic action. This study demonstrated that PPAR-gamma agonists could exert their actions by inducing antifibrotic hepatocyte growth factor (HGF) expression. Incubation of mesangial cells with natural or synthetic PPAR-gamma agonists 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) or troglitazone and ciglitazone suppressed TGF-beta1-mediated alpha-smooth muscle actin, fibronectin, and plasminogen activator inhibitor-1 expression. PPAR-gamma agonists also induced HGF mRNA expression and protein secretion. Transfection studies revealed that 15d-PGJ2 stimulated HGF gene promoter activity, which was dependent on the presence of a novel peroxisome proliferator response element. Treatment of mesangial cells with 15d-PGJ2 induced the binding of PPAR-gamma to the peroxisome proliferator response element in the HGF promoter region. PPAR-gamma agonists also activated c-met receptor tyrosine phosphorylation, induced Smad transcriptional co-repressor TG-interacting factor expression, and blocked TGF-beta/Smad-mediated gene transcription in mesangial cells. Furthermore, ablation of c-met receptor through the LoxP-Cre system in mesangial cells abolished the antifibrotic effect of 15d-PGJ2. PPAR-gamma activation also induced HGF expression in renal interstitial fibroblasts and repressed TGF-beta1-mediated myofibroblast activation. Both HGF and 15d-PGJ2 attenuated Smad nuclear translocation in response to TGF-beta1 stimulation in renal fibroblasts. Together, these findings suggest that HGF may act as a downstream effector that mediates the antifibrotic action of PPAR-gamma agonists.
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Affiliation(s)
- Yingjian Li
- Division of Cellular and Molecular Pathology, Department of Pathology, University of Pittsburgh, S-405 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261, USA
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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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447
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Loomans CJM, De Koning EJP, Staal FJT, Rabelink TJ, Zonneveld AJV. Endothelial progenitor cell dysfunction in type 1 diabetes: another consequence of oxidative stress? Antioxid Redox Signal 2005; 7:1468-75. [PMID: 16356109 DOI: 10.1089/ars.2005.7.1468] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Endothelial progenitor cells (EPC) have been shown to contribute to neovascularization and vascular maintenance and repair in adults. Recently, the concept has evolved that EPC dysfunction, in patients at risk for cardiovascular disease, may contribute to the development of atherosclerosis and ischemic vascular disease. Particularly, patients with diabetes mellitus are likely to be affected by EPC dysfunction as several studies have shown a reduced number and function of EPC in patients, as well as in preclinical models for type 1 diabetes. Here, we review our current understanding of EPC (dys)function in diabetes and discuss some potential mechanisms underlying their altered properties. Moreover, we provide circumstantial evidence indicating that increased oxidative stress could play a role in the development of EPC dysfunction in type 1 diabetes. Finally, we discuss the potential implication of our findings for EPC-based therapies and the potential impact of pharmacological interventions on the vascular regenerative capacity of EPC.
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Affiliation(s)
- Cindy J M Loomans
- Department of Nephrology, Leiden University Medical Center, Leiden, The Netherlands
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448
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Kobayashi T, Inoue T, Okada H, Kikuta T, Kanno Y, Nishida T, Takigawa M, Sugaya T, Suzuki H. Connective tissue growth factor mediates the profibrotic effects of transforming growth factor-beta produced by tubular epithelial cells in response to high glucose. Clin Exp Nephrol 2005; 9:114-21. [PMID: 15980944 DOI: 10.1007/s10157-005-0347-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Accepted: 03/02/2005] [Indexed: 01/04/2023]
Abstract
BACKGROUND It was reported that connective tissue growth factor (CTGF) was expressed in the tubular epithelial cells of the diabetic kidney. CTGF has, among other factors, been implicated in mediating the downstream, profibrotic effects of transforming growth factor-beta (TGF-beta), though is precise role in interstitial fibrogenesis in the diabetic kidney has not yet been clarified. METHODS We employed a coculture system involving cultured murine proximal tubular epithelial cells (mProx24) and renal fibroblasts (TFB), as a model of the subepithelial mesenchyme in the kidney in order to examine the profibrotic effects of CTGF derived from mProx24 cells in response to high glucose (30 mM). RESULTS We showed that glucose stimulated CTGF expression in cultured mProx24 in both a dose- and a time-dependent manner, and that this effect was mediated by increased levels of TGF-beta. We also found that high glucose significantly stimulated TFB cells to produce profibrotic molecules, such as type I collagen, the EIIIA isoform of fibronectin, and plasminogen activator inhibitor-1. The induction of these molecules was both direct and indirect, the latter induction being mediated by mProx24 cell-derived CTGF, which, in turn, was induced by TGF-beta that was produced by the mProx24 cells. CONCLUSIONS CTGF plays an important role in mediating renal interstitial fibrogenesis in response to high glucose and, as such, is a reasonable target for anti-fibrotic therapy.
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Affiliation(s)
- Tatsuya Kobayashi
- Department of Nephrology, Saitama Medical College, 38 Morohongo, Moroyama-machi, Saitama 350-0495, Japan
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449
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Pedchenko VK, Chetyrkin SV, Chuang P, Ham AJL, Saleem MA, Mathieson PW, Hudson BG, Voziyan PA. Mechanism of perturbation of integrin-mediated cell-matrix interactions by reactive carbonyl compounds and its implication for pathogenesis of diabetic nephropathy. Diabetes 2005; 54:2952-60. [PMID: 16186398 DOI: 10.2337/diabetes.54.10.2952] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Perturbation of interactions between cells and the extracellular matrix (ECM) of renal glomeruli may contribute to characteristic histopathological lesions found in the kidneys of patients with diabetic nephropathy. However, the mechanism by which the diabetic conditions may affect cell-ECM interactions is unknown. Existing hypotheses suggest a role of glucose in direct modification of ECM. Here, we have demonstrated that carbonyl compound methylglyoxal (MGO) completely inhibited endothelial cell adhesion to recombinant alpha3 noncollagenous 1 domain of type IV collagen mediated via a short collagenous region containing RGD (Arg-Gly-Asp) sequence as well as binding of purified alpha(v)beta(3) integrin to this protein. Specific MGO adducts of the arginine residue were detected within RGD sequence using mass spectrometry. Modification by carbonyl compounds glyoxal or glycolaldehyde had similar but smaller effects. MGO strongly inhibited adhesion of renal glomerular cells, podocytes, and mesangial cells to native collagen IV and laminin-1 as well as binding of collagen IV to its major receptor in glomerular cells, alpha(1)beta(1) integrin. In contrast, modification of these proteins by glucose had no effect on cell adhesion. Pyridoxamine, a promising drug for treatment of diabetic nephropathy, protected cell adhesion and integrin binding from inhibition by MGO. We suggest that in diabetes, perturbation of integrin-mediated cell-matrix interactions occurs via the modification of critical arginine residues in renal ECM by reactive carbonyl compounds. This mechanism may contribute to the development of diabetic nephropathy.
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Affiliation(s)
- Vadim K Pedchenko
- Division of Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2372, USA
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450
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Rossing K, Mischak H, Parving HH, Christensen PK, Walden M, Hillmann M, Kaiser T. Impact of diabetic nephropathy and angiotensin II receptor blockade on urinary polypeptide patterns. Kidney Int 2005; 68:193-205. [PMID: 15954909 DOI: 10.1111/j.1523-1755.2005.00394.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND New insights into the pathogenesis and treatment of diabetic renal disease may emerge from recent advances in proteomics using high-throughput mass spectrometry (MS) of urine. METHODS Using a combination of online capillary electrophoresis (CE) and MS we evaluated urinary polypeptide patterns in four groups of type 2 diabetic patients matched for age, gender, and diabetes duration, including 20 normoalbuminuric patients with and 20 without diabetic retinopathy, 20 microalbuminuric patients with diabetic retinopathy, and 18 macroalbuminuric patients with diabetic retinopathy. Furthermore, changes in urinary polypeptide patterns during treatment with the angiotensin II receptor blocker (ARB) candesartan were evaluated in the macroalbuminuric patients in a randomized double-blinded, cross-over trial where each patient received treatment with placebo, candesartan 8, 16, and 32 mg daily each for 2 months. RESULTS Overall, 4551 different polypeptides were found in the samples. Urinary polypeptide patterns were comparable in normo- (with and without diabetic retinopathy) and microalbuminuric patients, whereas distinct differences were found in macroalbuminuric patients. Differences in urinary polypeptide patterns between normo- and macroalbuminuric patients permitted the establishment of a "diabetic renal damage" pattern consisting of 113 polypeptides. Eleven of these polypeptides had been sequenced and identified. Candesartan treatment in macroalbuminuric patients significantly changed 15 of the 113 polypeptides in the diabetic renal damage pattern toward levels in normoalbuminuric patients. Change in the diabetic renal damage pattern was not candesartan dose-dependent but individual changes correlated with changes in urinary albumin excretion at each dose level. CONCLUSION CE-MS serves as a fast and sensitive tool for identification of biomarkers and urinary polypeptide patterns specific for macroalbuminuric type 2 diabetic patients and may be used to explore and monitor renoprotective effects of ARB.
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