Sirt1 resists advanced glycation end products-induced expressions of fibronectin and TGF-β1 by activating the Nrf2/ARE pathway in glomerular mesangial cells

• Published in: Free radical biology & medicine Vol. 65; pp. 528 - 540
• Main Authors: Huang, Kaipeng, Huang, Juan, Xie, Xi, Wang, Shaogui, Chen, Cheng, Shen, Xiaoyan, Liu, Peiqing, Huang, Heqing
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2013
• Subjects: advanced glycation end products; Animals; antioxidant activity; Blotting, Western; Diabetes Mellitus, Experimental - metabolism; Diabetic Nephropathies - metabolism; diabetic nephropathy; DNA; Electrophoretic Mobility Shift Assay; fibronectins; Fibronectins - biosynthesis; fibrosis; Fluorescent Antibody Technique; gene expression regulation; gene overexpression; genes; glycation; Glycation End Products, Advanced - metabolism; heme oxygenase (biliverdin-producing); Immunoprecipitation; kidneys; Male; Mesangial Cells - metabolism; NF-E2-Related Factor 2 - metabolism; oxidative stress; protein synthesis; Rats; Rats, Sprague-Dawley; reactive oxygen species; resveratrol; Signal Transduction - physiology; Sirtuin 1 - metabolism; superoxide dismutase; transcription (genetics); Transfection; transforming growth factor beta 1; Transforming Growth Factor beta1 - biosynthesis; Oxidative stress; FN; glomerular messangial cells; DN; HO-1; MDA; mitogen-activated protein kinase; BSA; electrophoretic mobility shift assay; Advanced glycation end products; Nrf2; EMSA; GMCs; reactive oxygen species; STZ; Diabetic nephropathy; malonaldehyde; manganese superoxide dismutase; transforming growth factor-β1; kelch like ECH-associated protein 1; resveratrol; antioxidant response element; heme oxygenase 1; protein kinase C; Nrf2/ARE pathway; nuclear factor E2-related factor 2; PKC; AGEs; MAPK; ECM; OSS; streptozocin; ARE; RSV; fibronectin; nicotinamide adenosine dinucleotide(+); MnSOD; ROS; Keap1; NAD(+); TGF-β1; Sirt1; bovine serum albumin; extracellular matrix
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2013.07.029

Advanced glycation end products (AGEs) boost the generation of reactive oxygen species (ROS) in glomerular mesangial cells (GMCs), and thereby play important roles in diabetic nephropathy (DN). Sirtuin 1 (Sirt1), a protein deacetylase, is known to markedly protect cells from oxidative stress (OSS) injury. Based on the critical involvements of AGEs and Sirt1 in OSS, Sirt1 is postulated to resist AGEs-induced diabetic renal fibrosis through its antioxidative effects. The current study was designed to explore the inhibitory effect of Sirt1 on the expressions of fibronectin (FN) and transforming growth factor-β1 (TGF-β1) induced by AGEs in GMCs. The molecular mechanism by which Sirt1 promoted the activation of the antioxidative pathway was further investigated. The following findings were obtained: (1) the treatment of GMCs with AGEs decreased Sirt1 levels in terms of protein expression and activity but increased FN and TGF-β1 levels in a dose- and time-dependent manner; (2) resveratrol or Sirt1 overexpression markedly increased Sirt1 levels and reduced FN and TGF-β1 expressions; (3) inhibition of Sirt1 activity further induced the productions of FN and TGF-β1; (4) Sirt1 promoted the nuclear accumulation, DNA binding, and transcriptional activities of Nrf2 and upregulated the expressions of Nrf2 downstream genes, heme oxygenase-1, and superoxide dismutase 1; ROS levels induced by AGEs eventually reduced in a deacetylase-dependent manner; and (5) with the deposition of AGEs in the kidneys, the diabetic rats suffered severe renal dysfunction and high OSS levels; resveratrol treatment evidently diminished the OSS levels, ameliorated renal injury, and prevented the expressions of FN and TGF-β1 in the kidneys of diabetic rats. This work supports a negative role of Sirt1 in AGE-induced overproductions of FN and TGF-β1. The molecular mechanisms that underlie the beneficial effects of Sirt1 on DN correlate well with the activation of the Nrf2/ARE antioxidative pathway.