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Dong R, Yu J, Yu F, Yang S, Qian Q, Zha Y. IGF-1/IGF-1R blockade ameliorates diabetic kidney disease through normalizing Snail1 expression in a mouse model. Am J Physiol Endocrinol Metab 2019; 317:E686-E698. [PMID: 31361542 DOI: 10.1152/ajpendo.00071.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This study investigated the role of insulin-like growth factor-1/insulin-like growth factor-1 receptor (IGF-1/IGF-1R) in the genesis and progression of diabetic kidney disease (DKD) in a streptozotocin (STZ)-induced mouse diabetes model. We showed elevated IGF-1 expression in the DKD kidneys after 16 wk of diabetic onset. Intraperitoneal administration of IGF-1R inhibitor (glycogen synthase kinase-3β, GSK4529) from week 8 to week 16 postdiabetes induction ameliorated urinary albumin excretion and kidney histological changes due to diabetes, including amelioration of glomerulomegaly, inflammatory infiltration, and tubulointerstitial fibrosis. The GSK4529 treatment also attenuated alterations in renal tubular expression of E-cad and matrix protein fibronectin. Moreover, renal fibrosis in DKD (without treatment) was associated with Snail1 overexpression that was effectively prevented by IGF-1R inhibition. Further experiments in cultured renal epithelial cells (NRK) showed that IGF-1 silencing reproduced in vivo effects of IGF-1R inhibition with markedly attenuated Snail1 expression and near normalization of the Ecad1 and fibronectin expression pattern. Further Snail1 silencing prevented high-glucose-induced changes without affecting IGF-1 expression, consistent with Snail1 acting downstream to IGF-1. The antifibrotic effects were also shown with benazepril or insulin treatment but to a much lesser degree. In summary, in STZ-induced diabetic mice, activation of IGF-1 in diabetic kidneys induces fibrogenesis through Snail1 upregulation. The diabetes-related histological and functional changes, as well as fibrogenesis, can be attenuated by IGF-1/IGF-1R inhibition.
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Affiliation(s)
- Rong Dong
- Guizhou University School of medicine, Gui Yang, China
- Department of Nephrology, Guizhou Provincial People's Hospital, Gui Yang, China
- NHC Key Laboratory of Pulmonary Immunological Diseases, Guizhou Provincial People's Hospital, Gui Yang, China
| | - Jiali Yu
- Department of Nephrology, Guizhou Provincial People's Hospital, Gui Yang, China
| | - Funxun Yu
- NHC Key Laboratory of Pulmonary Immunological Diseases, Guizhou Provincial People's Hospital, Gui Yang, China
| | - Song Yang
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for Research and Development of Fine Chemicals, Guizhou University, Gui Yang, China
| | - Qi Qian
- Department of Medicine, Division of Nephrology and Hypertension, Mayo Clinic, College of Medicine, Rochester, Minnesota
| | - Yan Zha
- Guizhou University School of medicine, Gui Yang, China
- Department of Nephrology, Guizhou Provincial People's Hospital, Gui Yang, China
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2
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Yamasaki A, Bito D, Eto E, Matsumoto K, Nakamura M, Miyazaki J, Matsumoto K, Masuda M, Mori D, Yoshimura T. Focal segmental glomerulosclerosis in which urinary protein improved after surgical treatment for acromegaly: a case report. J Med Case Rep 2019; 13:298. [PMID: 31540583 PMCID: PMC6754629 DOI: 10.1186/s13256-019-2228-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/09/2019] [Indexed: 11/23/2022] Open
Abstract
Background Focal segmental glomerulosclerosis is characterized by partial (segmental) sclerotic lesions in some glomeruli (focal). Primary focal segmental glomerulosclerosis is generally considered resistant to steroid therapy. However, acromegaly is a disease that causes peculiar facial features, body types, and metabolic abnormalities due to the excessive secretion of growth hormone by a pituitary adenoma. Growth hormone has been reported to be involved in glomerular cell growth, mesangial proliferation, and glomerulosclerosis in the kidney. Case presentation We report a case of a Japanese patient with focal segmental glomerulosclerosis in whom decreased urinary protein was observed after surgical treatment for acromegaly. Conclusion The patient’s urinary protein improved as the concentration of growth hormone/insulin-like growth factor 1 decreased.
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Affiliation(s)
- Arina Yamasaki
- Diabetes and Endocrinology, Saga-Ken Medical Centre Koseikan, 400 Nakabaru, Kase-machi, Saga-shi, Saga, 840-8571, Japan.
| | - Daisuke Bito
- Diabetes and Endocrinology, Saga-Ken Medical Centre Koseikan, 400 Nakabaru, Kase-machi, Saga-shi, Saga, 840-8571, Japan
| | - Erina Eto
- Diabetes and Endocrinology, Saga-Ken Medical Centre Koseikan, 400 Nakabaru, Kase-machi, Saga-shi, Saga, 840-8571, Japan
| | | | | | - Junji Miyazaki
- Otorhinolaryngology, Saga-Ken Medical Centre Koseikan, Saga, Japan
| | | | - Masanori Masuda
- Diagnostic Pathology, Saga-Ken Medical Centre Koseikan, Saga, Japan
| | - Daisuke Mori
- Diagnostic Pathology, Saga-Ken Medical Centre Koseikan, Saga, Japan
| | - Toru Yoshimura
- Diabetes and Endocrinology, Saga-Ken Medical Centre Koseikan, 400 Nakabaru, Kase-machi, Saga-shi, Saga, 840-8571, Japan
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3
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Kunjara S, Greenbaum AL, McLean P, Grønbaek H, Flyvbjerg A. Effects of long-term experimental diabetes on adrenal gland growth and phosphoribosyl pyrophosphate formation in growth hormone-deficient dwarf rats. Int J Exp Pathol 2012; 93:196-201. [PMID: 22583133 DOI: 10.1111/j.1365-2613.2012.00818.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The availability of growth hormone (GH)-deficient dwarf rats with otherwise normal pituitary function provides a powerful tool to examine the relative role of hyperglycaemia and the reordering of hormonal factors in the hypertrophy-hyperfunction of the adrenal gland that is seen in experimental diabetes. Here, we examine the effects of long-term (6 months) experimental diabetes on the growth of the adrenal glands; their content of phosphoribosyl pyrophosphate (PRPP); and the activity of the PRPP synthetase, G6P dehydrogenase and 6PG dehydrogenase enzymes in GH-deficient dwarf rats compared to heterozygous controls. These parameters were selected in view of the known role of PRPP in both de novo and salvage pathways of purine and pyrimidine synthesis and in the formation of NAD, and in view of the role of the oxidative enzymes of the pentose phosphate pathway in both R5P formation and the generation of the NADPH that is required in reductive synthetic reactions. This study shows that GH deficiency prevents the increase in adrenal gland weight, PRPP synthetase, PRPP content and G6P dehydrogenase and 6PG dehydrogenase. This contrasts sharply with the heterozygous group that showed the expected increase in these parameters. The blood glucose levels of the groups of long-term diabetic rats, both GH-deficient and heterozygous, remained at an elevated level throughout the experiment. These results are fully in accord with earlier evidence from studies with somatostatin analogues which showed that the GH-insulin-like growth factor I (IGF-I)-axis plays a key role in the adrenal diabetic hypertrophy-hyperfunction syndrome.
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Affiliation(s)
- Sirilaksana Kunjara
- Division of Biosciences, Research Department of Cell and Development Biology, University College London, Gower Street, London WC1E 6BT, UK
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4
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Troib A, Landau D, Youngren JF, Kachko L, Rabkin R, Segev Y. The effects of type 1 IGF receptor inhibition in a mouse model of diabetic kidney disease. Growth Horm IGF Res 2011; 21:285-291. [PMID: 21865067 PMCID: PMC4238882 DOI: 10.1016/j.ghir.2011.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 06/26/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
Abstract
OBJECTIVE We have recently shown increased sensitivity to IGF-I induced signal transduction in kidneys of diabetic mice. Accordingly we investigated the effects of PQ401, a novel diarylurea compound that inhibits IGF1R autophosphorylation in type I diabetes. METHODS Control (C) and Diabetic (D) mice were administered PQ401 (CP, DP) or vehicle (C, D) for 3weeks. RESULTS CP animals showed a decrease in renal phosphorylated (p-)AKT and p-IGF1R. However, PQ401 had no effect on diabetic state (hyperglycemia, weight loss) or renal disease parameters (hypertrophy, hyperfiltration and albuminuria). Type IV collagen as well as TGF-β mRNA increased in DP and D compared to C. In the CP group renal hypertrophy with fat accumulation in proximal tubuli and increased renal IGF-I, collagen IV and TGF-β mRNA were seen. CONCLUSIONS IGF1R inhibition by PQ401 exerted no significant effects on diabetic kidney disease parameters, arguing against a role for IGF-I in the pathogenesis of diabetic kidney disease. However, PQ401 affects normal kidneys, inducing renal hypertrophy as well as collagen and fat accumulation, with increased renal IGF-I mRNA, suggestive of a damage-regeneration process. Therefore, this diarylurea compound is not beneficial in early diabetic kidney disease. Its potential deleterious effects on kidney tissue need to be further investigated.
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Affiliation(s)
- Ariel Troib
- Shraga Segal Department of Microbiology and Immunology, Ben Gurion University of the Negev, Beer Sheva, Israel
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Kumar PA, Brosius FC, Menon RK. The glomerular podocyte as a target of growth hormone action: implications for the pathogenesis of diabetic nephropathy. Curr Diabetes Rev 2011; 7:50-5. [PMID: 21067510 PMCID: PMC4007067 DOI: 10.2174/157339911794273900] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 09/10/2010] [Indexed: 01/28/2023]
Abstract
Involvement of the growth hormone (GH) / insulin-like growth factor 1 (IGF-I) axis in the pathogenesis of diabetic nephropathy (DN) is strongly suggested by studies investigating the impact of GH excess and deficiency on renal structure and function. GH excess in both the human (acromegaly) and in transgenic animal models is characterized by significant structural and functional changes in the kidney. In the human a direct relationship has been noted between the activity of the GH/IGF-1 axis and renal hypertrophy, microalbuminuria, and glomerulosclerosis. Conversely, states of GH deficiency or deficiency or inhibition of GH receptor (GHR) activity confer a protective effect against DN. The glomerular podocyte plays a central and critical role in the structural and functional integrity of the glomerular filtration barrier and maintenance of normal renal function. Recent studies have revealed that the glomerular podocyte is a target of GH action and that GH's actions on the podocyte could be detrimental to the structure and function of the podocyte. These results provide a novel mechanism for GH's role in the pathogenesis of DN and offer the possibility of targeting the GH/IGF-1 axis for the prevention and treatment of DN.
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Affiliation(s)
- P Anil Kumar
- Pediatrics & Communicable Diseases, University of Michigan, Ann Arbor, MI 48109-0718, USA
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6
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Swindell WR, Masternak MM, Bartke A. In vivo analysis of gene expression in long-lived mice lacking the pregnancy-associated plasma protein A (PappA) gene. Exp Gerontol 2010; 45:366-74. [PMID: 20197085 DOI: 10.1016/j.exger.2010.02.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 02/16/2010] [Accepted: 02/18/2010] [Indexed: 01/15/2023]
Abstract
Mice lacking the pregnancy-associated plasma protein A (PappA) gene exhibit diminished localized IGF-1 bioavailability and a 30% increase in mean life span. However, it is uncertain which tissues exhibit reduced IGF-1 signals in the PappA(-/-) mouse, and whether effects of this mutation parallel those of mutations that diminish IGF-1 in serum. Across a panel of 21 tissues, we used RT-PCR to evaluate the effects of the PappA(-/-) mutation on expression of Igfbp5, which served as an in vivo indicator of IGF-1 signaling. Among these tissues, expression of Igfbp5 was significantly reduced by PappA(-/-) only in kidney. A broader survey of IGF-associated genes in six organs identified five other genes responsive to PappA(-/-) in kidney, with stronger effects in this organ relative to other tissues. Renal expression of Irs1 and Mt1 was increased by PappA(-/-) as well as by mutations that reduce IGF-1 in serum (i.e., Ghr(-/-), Pit1(dw/dw) and Prop1(df/df)), and we demonstrate that expression of these genes is regulated by growth hormone-treatment and calorie restriction. These results provide in vivo data on an important new model of mammalian aging, and characterize both similar and contrasting expression patterns between long-lived mice with reduced local IGF-1 availability and diminished IGF-1 in serum.
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Affiliation(s)
- William R Swindell
- University of Michigan, Department of Pathology and Geriatrics Center, Ann Arbor, MI 48109-2200, USA.
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7
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Identification of compounds that inhibit IGF-I signaling in hyperglycemia. EXPERIMENTAL DIABETES RESEARCH 2010; 2009:267107. [PMID: 20111736 PMCID: PMC2810469 DOI: 10.1155/2009/267107] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Accepted: 11/09/2009] [Indexed: 11/23/2022]
Abstract
Increased
responsiveness of vascular cells to the growth
factor IGF-I has been implicated in
complications associated with diabetes. Here we
describe the development of an assay and
screening of a library of compounds for their
ability to accelerate cleavage of the
transmembrane protein integrin-associated
protein (IAP) thereby disrupting the association
between IAP and SHPS-1 which we have shown as
critical for the enhanced response of vascular
cells to IGF-I. The cell-based ELISA utilizes an
antibody that specifically detects cleaved, but
not intact, IAP. Of the 1040 compounds tested, 14
were considered active by virtue of their
ability to stimulate an increase in antibody-binding indicative of IAP cleavage. In
experiments with smooth muscle and retinal
endothelial cell cultures in hyperglycemic
conditions, each active compound was shown to
accelerate the cleavage of IAP, and this was
associated with a decrease in IAP association
with SHPS-1 as determined by
coimmunoprecipitation of the proteins from cell
lysates. As a consequence of the acceleration in
IAP cleavage, the compounds were shown to inhibit
IGF-I-stimulated phosphorylation of key
signaling molecules including Shc and ERK1/2, and
this in turn was associated with a decrease in
IGF-I-stimulated cell proliferation.
Identification of these compounds that utilize
this mechanism has the potential to yield novel
therapeutic approaches for the prevention and
treatment of vascular complications associated
with diabetes.
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8
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Vasylyeva TL, Ferry RJ. Novel roles of the IGF-IGFBP axis in etiopathophysiology of diabetic nephropathy. Diabetes Res Clin Pract 2007; 76:177-86. [PMID: 17011663 PMCID: PMC1892792 DOI: 10.1016/j.diabres.2006.09.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2006] [Accepted: 09/04/2006] [Indexed: 11/25/2022]
Abstract
Mechanisms contributing to development of diabetic nephropathy (DN) remain unclear. High ambient glucose level transforms intracellular pathways, promoting stable phenotypic changes in the glomerulus such as mesangial cell hypertrophy, podocyte apoptosis, and matrix expansion. Insulin-like growth factors (IGFs) and the high affinity IGF binding proteins (IGFBPs) exert major effects on cell growth and metabolism. Compared with diabetic patients without microalbuminuria (MA), MA diabetic patients display perturbed GH-IGF-IGFBP homeostasis, including increased circulating IGF-I and IGFBP-3 protease activity, increased excretion of bioactive GH, IGF-I, and IGFBP-3, but decreased circulating IGFBP-3 levels. In diabetic animal models, expression of IGF-I and IGFBP-1 to -4 increases in key renal tissues and glomerular ulrafiltrate. Epithelial, mesangial, and endothelial cells derived from the kidney respond to IGF-I binding with increased protein synthesis, migration, and proliferation. This article reviews classic and emerging concepts for the roles of the GH-IGF-IGFBP axis in the etiopathophysiology, treatment, and prevention of diabetic renal disease. We report IGF-independent actions of IGFBP-3 in the podocyte for the first time.
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Affiliation(s)
- Tetyana L Vasylyeva
- Department of Pediatrics, Texas Tech University Health Science Center, Amarillo, TX, USA
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9
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Stephens RH, McElduff P, Heald AH, New JP, Worthington J, Ollier WE, Gibson JM. Polymorphisms in IGF-binding protein 1 are associated with impaired renal function in type 2 diabetes. Diabetes 2005; 54:3547-53. [PMID: 16306374 DOI: 10.2337/diabetes.54.12.3547] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The dysregulation of the IGF system has been implicated in the pathogenesis of obesity, diabetes, and diabetes complications such as nephropathy, but little is known about the genomics of the IGF system in health and disease. We genotyped 13 single nucleotide polymorphisms (SNPs) in IGFBP1 gene in 732 representative type 2 diabetic patients from the Salford Diabetes Register. Of the 13 SNPs, 8 were polymorphic and 7 of those had minor allele frequencies >0.1, one of which was in the gene promoter and one of which was nonsynonymous in exon 4. The minor alleles of these SNPs and two others were associated with a reduced prevalence of diabetic nephropathy. Haplotype analysis revealed that 97% of the genetic variation for IGFBP1 in the population sample could be accounted for using two of the "reno-protective" SNPs, with other SNPs adding little extra information. One of these two SNPs was the nonsynonymous mutation in exon 4, lying close to the integrin-binding RGD motif, which is thought to affect tissue delivery of IGF-I by IGF-binding protein 1 (IGFBP-1), possibly suggesting a "reno-protective" effect via altered IGFBP-1 binding. In conclusion, we have described the first genomic markers to be associated with diabetic microvascular complications within the human IGFBP1 gene.
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10
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Kang BPS, Urbonas A, Baddoo A, Baskin S, Malhotra A, Meggs LG. IGF-1 inhibits the mitochondrial apoptosis program in mesangial cells exposed to high glucose. Am J Physiol Renal Physiol 2003; 285:F1013-24. [PMID: 12876069 DOI: 10.1152/ajprenal.00209.2003] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The activated insulin-like growth factor-1 receptor (IGF-1R) protects cells from a wide range of apoptotic stimuli. Hyperglycemia promotes the intracellular generation of superoxide anion and hydrogen peroxide, both of which have been linked to the activation of the mitochondrial apoptosis program. Here, we report for the first time that ligand activation of the IGF-1R protects normal human mesangial cells and SV40 murine mesangial cells from the glycol-oxidant-induced apoptosis program. The IGF-1R antiapoptosis program was dependent on the recruitment of both Akt/PKB and the ERK subfamily of mitogen-activated protein kinases. IGF-1 treatment also protected the redox potential of mesangial cells maintained at high ambient glucose concentration, by inhibiting the generation of reactive oxygen intermediates and preserving mitochondrial transmembrane potential. IGF-1R survival signals targeted the Bcl-2 family of proteins to protect against glucose-induced apoptosis and oxidative stress. IGF-1-treated cells exhibited a decrease in the Bax/Bcl-2 ratio; increased phosphorylation/inactivation of Bad at Ser112 and Ser136; inhibition of cytochrome c release; perturbations directionally opposed to the initiation of the apoptosis program. In addition, we demonstrate IGF-1R-activated ERK signaling modules phosphorylate Ser112 of the mitochondrial Bad protein, establishing a direct link between surface IGF-1R and the survival program in mitochondria. Our findings indicate that in mesangial cells maintained at high ambient glucose concentration, IGF-1 activates a survival program that maintains the integrity of mitochondria and prevents the expression of the genetic program for apoptosis.
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Affiliation(s)
- Barinder P S Kang
- Division of Nephrology, Department of Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103, USA
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Flyvbjerg A, Schrijvers BF, De Vriese AS, Tilton RG, Rasch R. Compensatory glomerular growth after unilateral nephrectomy is VEGF dependent. Am J Physiol Endocrinol Metab 2002; 283:E362-6. [PMID: 12110543 DOI: 10.1152/ajpendo.00007.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Various growth factors and cytokines have been implicated in different forms of kidney enlargement. Vascular endothelial growth factor (VEGF) is essential for normal renal development and plays a role in diabetic glomerular enlargement. To explore a possible role for VEGF in compensatory renal changes after uninephrectomy, we examined the effect of a neutralizing VEGF-antibody (VEGF-Ab) on glomerular volume and kidney weight in mice treated for 7 days. Serum and kidney insulin-like growth factor I (IGF-I) levels were measured, since IGF-I has been implicated in the pathogenesis of compensatory renal growth, and VEGF has been suggested to be a downstream mediator of IGF-I. Placebo-treated uninephrectomized mice displayed an early transient increase in kidney IGF-I concentration and an increase in glomerular volume and kidney weight. In VEGF-Ab-treated uninephrectomized animals, increased glomerular volume was abolished, whereas renal hypertrophy was partially blocked. Furthermore, the renal effects of VEGF-Ab administration were seen without affecting the renal IGF-I levels. In conclusion, these results demonstrate that compensatory glomerular growth after uninephrectomy is VEGF dependent.
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Affiliation(s)
- Allan Flyvbjerg
- Medical Department M, Medical Research Laboratories, Institute of Experimental Clinical Research, Aarhus University, DK-8000 Aarhus, Denmark.
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12
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Thirone ACP, Scarlett JA, Gasparetti AL, Araujo EP, Lima MHL, Carvalho CRO, Velloso LA, Saad MJA. Modulation of growth hormone signal transduction in kidneys of streptozotocin-induced diabetic animals: effect of a growth hormone receptor antagonist. Diabetes 2002; 51:2270-81. [PMID: 12086960 DOI: 10.2337/diabetes.51.7.2270] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Growth hormone (GH) and IGFs have a long distinguished history in diabetes, with possible participation in the development of renal complications. The implicated effect of GH in diabetic end-stage organ damage may be mediated by growth hormone receptor (GHR) or postreceptor events in GH signal transduction. The present study investigates the effects of diabetes induced by streptozotocin (STZ) on renal GH signaling. Our results demonstrate that JAK2, insulin receptor substrate (IRS)-1, Shc, ERKs, and Akt are widely distributed in the kidney, and after GH treatment, there is a significant increase in phosphorylation of these proteins in STZ-induced diabetic rats compared with controls. Moreover, the GH-induced association of IRS-1/phosphatidylinositol 3-kinase, IRS-1/growth factor receptor bound 2 (Grb2), and Shc/Grb2 are increased in diabetic rats as well. Immunohistochemical studies show that GH-induced p-Akt and p-ERK activation is apparently more pronounced in the kidneys of diabetic rats. Administration of G120K-PEG, a GH antagonist, in diabetic mice shows inhibitory effects on diabetic renal enlargement and reverses the alterations in GH signal transduction observed in diabetic animals. The present study demonstrates a role for GH signaling in the pathogenesis of early diabetic renal changes and suggests that specific GHR blockade may present a new concept in the treatment of diabetic kidney disease.
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Affiliation(s)
- Ana C P Thirone
- Department of Internal Medicine, FCM, State University Of Campinas, 13080-970 Campinas, Sao Paulo, Brazil
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13
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Jørgensen CS, Ahrensberg JM, Gregersen H, Flyvberg A. Tension-strain relations and morphometry of rat small intestine in experimental diabetes. Dig Dis Sci 2001; 46:960-7. [PMID: 11341665 DOI: 10.1023/a:1010737323153] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Tension-strain relations and morphometric data were studied in isolated segments of the jejunum and distal ileum in untreated diabetic rats, insulin-treated diabetic rats, and nondiabetic control rats. Diabetes was induced by a single intravenous injection of streptozotocin (28 mg/kg body wt). All injected rats developed hyperglycemia. The experiment was terminated after 28 days and the intestinal segments were superfused with saline solution containing papaverine to abolish contractile activity. Stepwise inflation of a balloon in which the cross-sectional area (CSA) was measured provided the luminal pressure-loading stimulus. The circumferential tension-strain relation was derived from steady-state values of internal radius and applied pressure. The intestinal weight, length, and weight per unit length increased significantly in untreated diabetic rats compared to the two other groups (P < 0.05). The body weight decreased in untreated diabetic rats compared to the two other groups (P < 0.05). The pressure-CSA relations differed between jejunum and distal ileum (P < 0.001) but not between the groups (P > 0.2). The tension-strain relations in jejunum and distal ileum were nonlinear and the curves for the two diabetic groups were shifted to the left compared to the curve for controls (P < 0.05), indicating increased wall stiffness. The histomorphometric data showed increased wall thickness in untreated diabetic rats compared to the two other groups both in jejunum and distal ileum (P < 0.02). Mucosal, submucosal, and muscle layer thicknesses did not differ between the three groups. No significant association was found between the histomorphometric and biomechanical parameters.
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Affiliation(s)
- C S Jørgensen
- Institute of Experimental Clinical Research, Aarhus University, Denmark
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14
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Bach LA, Dean R, Youssef S, Cooper ME. Aminoguanidine ameliorates changes in the IGF system in experimental diabetic nephropathy. Nephrol Dial Transplant 2000; 15:347-54. [PMID: 10692520 DOI: 10.1093/ndt/15.3.347] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Formation of advanced glycation end-products (AGEs) has been implicated in the development of diabetic complications. As well as causing changes in structural proteins, AGEs may also alter gene expression of growth factors in vitro. The insulin-like growth factor (IGF) system, including IGF-I and modulatory IGF binding proteins (IGFBPs), is dysregulated during the development of diabetic nephropathy. METHODS Quantitative in situ hybridization histochemistry and immunohistochemistry were used to determine the effects of aminoguanidine, an inhibitor of AGE formation, on gene expression of IGF-I and IGFBPs in kidneys of long-term (8 months duration) streptozotocin-diabetic rats. RESULTS Diabetes was associated with increased renal expression of IGFBP-1 mRNA (diabetes 824+/-236 vs control 264+/-76 arbitrary units, P<0.01) and decreased expression of mRNAs for IGF-I (diabetes 39+/-7 vs control 185+/-23 arbitrary units, P<0.001) and IGFBP-4 (diabetes 139+/-25 vs control 383+/-54 arbitrary units, P<0.001). Aminoguanidine treatment inhibited the effects of diabetes on renal expression of mRNA for IGF-I, IGFBP-1 and IGFBP-4. The changes in IGF-I and IGFBP-1 mRNA levels were reflected in altered peptide levels. In diabetic kidneys, IGFBP-5 mRNA levels were slightly decreased to 75% of control levels (P<0.01); aminoguanidine had no effect on IGFBP-5 mRNA levels. CONCLUSIONS These results suggest that amelioration of changes in the renal IGF system by aminoguanidine may contribute to the renoprotective effects of the latter, which have been previously shown to inhibit structural and functional aspects of diabetic nephropathy in the rat.
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Affiliation(s)
- L A Bach
- University of Melbourne, Department of Medicine, Austin and Repatriation Medical Centre, Heidelberg, Victoria, Australia
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