cyclin-d1 and Diabetic-Angiopathies

Vascular remodeling induced by long‑term hyperglycaemia is the main pathological process in diabetic vascular complications. Thus, vascular remodeling may be a potential therapeutic target in diabetes mellitus (DM) with macrovascular disease. The present study aimed to investigate the effect of RING finger protein 10 (RNF10) on vascular remodeling under conditions of chronic hyperglycaemia stimulation. We found that overexpression of RNF10 clearly decreased intimal thickness and attenuated vascular remodeling in DM. TUNEL staining showed that apoptosis was clearly inhibited, an effect that may be mediated by decreases in Bcl‑2 protein expression. Quantitative analysis demonstrated that overexpression of RNF10 could suppress inflammation by reducing the levels of TNF‑α, and MCP‑1 mRNA and NF‑κB protein. Meanwhile, overexpression of RNF10 prevented vascular smooth muscle cell (VSMC) hyperproliferation through the downregulation of cyclin D1 and CDK4 proteins. Notably, short hairpin RNF10 (shRNF10) greatly aggravated the pathological responses of diabetic vascular remodeling. These outcomes revealed that the differential expression of RNF10 had a completely opposite effect on vascular damage under hyperglycaemia, further displaying the core function of RNF10 in regulating vascular remodeling induced by diabetes. Consequently, RNF10 could be a novel target for the treatment of diabetic vascular complications.

Topics: Animals; Apoptosis; Carotid Arteries; Carrier Proteins; Chemokine CCL2; Cyclin D1; Cyclin-Dependent Kinase 4; Diabetes Mellitus, Experimental; Diabetic Angiopathies; Diet, High-Fat; Gene Expression Regulation; Humans; Hyperglycemia; Insulin Resistance; Male; Myocytes, Smooth Muscle; Nerve Tissue Proteins; NF-kappa B; Rats; Rats, Sprague-Dawley; RNA, Small Interfering; Signal Transduction; Tumor Necrosis Factor-alpha

The high glucose-induced proliferation of vascular smooth muscle cells (VSMCs) plays an important role in the development of diabetic vascular diseases. In a previous study, we confirmed that Interferon regulatory factor-1 (Irf-1) is a positive regulator of the high glucose-induced proliferation of VSMCs. However, the mechanisms remain to be determined.. The levels of cyclin/CDK expression in two cell models involving Irf-1 knockdown and overexpression were quantified to explore the relationship between Irf-1 and its downstream effectors under normal or high glucose conditions. Subsequently, cells were treated with high glucose/NAC, normal glucose/H₂O₂, high glucose/U0126 or normal glucose/H₂O₂/U0126 during an incubation period. Then proliferation, cyclin/CDK expression and cell cycle distribution assays were performed to determine whether ROS/Erk1/2 signaling pathway was involved in the Irf-1-induced regulation of VSMC growth under high glucose conditions.. We found that Irf-1 overexpression led to down-regulation of cyclin D1/CDK4 and inhibited cell cycle progression in VSMCs under normal glucose conditions. In high glucose conditions, Irf-1 overexpression led to an up-regulation of cyclin E/CDK2 and an acceleration of cell cycle progression, whereas silencing of Irf-1 suppressed the expression of both proteins and inhibited the cell cycle during the high glucose-induced proliferation of VSMCs. Treatment of VSMCs with antioxidants prevented the Irf-1 overexpression-induced proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression in high glucose conditions. In contrast, under normal glucose conditions, H₂O₂ stimulation and Irf-1 overexpression induced cell proliferation, up-regulated cyclin E/CDK2 expression and promoted cell cycle acceleration. In addition, overexpression of Irf-1 promoted the activation of Erk1/2 and when VSMCs overexpressing Irf-1 were treated with U0126, the specific Erk1/2 inhibitor abolished the proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression under high glucose or normal glucose/H₂O₂ conditions.. These results demonstrate that the downstream effectors of Irf-1 are cyclin E/CDK2 during the high glucose-induced proliferation of VSMCs, whereas they are cyclin D1/CDK4 in normal glucose conditions. The Irf-1 overexpression-induced proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression are associated with ROS/Erk1/2 signaling pathway under high glucose conditions.

Topics: Animals; Antioxidants; Cell Cycle; Cell Proliferation; Cells, Cultured; Cyclin D1; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 4; Diabetic Angiopathies; Extracellular Signal-Regulated MAP Kinases; Glucose; Interferon Regulatory Factor-1; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; RNA Interference; Signal Transduction; Transfection; Up-Regulation

Increased levels of C-peptide, a cleavage product of proinsulin, circulate in patients with insulin resistance and early type 2 diabetes mellitus. Recent data suggest a potential causal role of C-peptide in atherogenesis by promoting monocyte and T-lymphocyte recruitment into the vessel wall. The present study examined the effect of C-peptide on vascular smooth muscle cells (VSMCs) proliferation and evaluated intracellular signaling pathways involved. In early arteriosclerotic lesions of diabetic subjects, C-peptide colocalized with VSMCs in the media. In vitro, stimulation of human or rat VSMCs with C-peptide induced cell proliferation in a concentration-dependent manner with a maximal 2.6+/-0.8-fold induction at 10 nmol/L human C-peptide (P<0.05 compared with unstimulated cells; n=9) and a 1.8+/-0.2-fold induction at 0.5 nmol/L rat C-peptide (P<0.05 compared with unstimulated cells; n=7), respectively, as shown by [H3]-thymidin incorporation. The proliferative effect of C-peptide on VSMCs was inhibited by Src short interference RNA transfection, PP2, an inhibitor of Src-kinase, LY294002, an inhibitor of PI-3 kinase, and the ERK1/2 inhibitor PD98059. Moreover, C-peptide induced phosphorylation of Src, as well as activation of PI-3 kinase and ERK1/2, suggesting that these signaling molecules are involved in C-peptide-induced VSMC proliferation. Finally, C-peptide induced cyclin D1 expression as well as phosphorylation of Rb in VSMCs. Our results demonstrate that C-peptide induces VSMC proliferation through activation of Src- and PI-3 kinase as well as ERK1/2. These data suggest a novel mechanism how C-peptide may contribute to plaque development and restenosis formation in patients with insulin resistance and early type 2 diabetes mellitus.

Topics: Animals; Arteriosclerosis; C-Peptide; Cell Proliferation; Cells, Cultured; Cyclin D1; Diabetic Angiopathies; Enzyme Activation; Humans; Intracellular Membranes; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phosphatidylinositol 3-Kinases; Phosphorylation; Phosphotransferases; Proto-Oncogene Proteins c-akt; Rats; Retinoblastoma Protein; Signal Transduction; src-Family Kinases