Interferon regulatory factor-1 together with reactive oxygen species promotes the acceleration of cell cycle progression by up-regulating the cyclin E and CDK2 genes during high glucose-induced proliferation of vascular smooth muscle cells

Cardiovasc Diabetol. 2013 Oct 14:12:147. doi: 10.1186/1475-2840-12-147.

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

MeSH terms

  • Animals
  • Antioxidants / pharmacology
  • Cell Cycle* / drug effects
  • Cell Proliferation* / drug effects
  • Cells, Cultured
  • Cyclin D1 / metabolism
  • Cyclin E / metabolism*
  • Cyclin-Dependent Kinase 2 / metabolism*
  • Cyclin-Dependent Kinase 4 / metabolism
  • Diabetic Angiopathies / enzymology*
  • Diabetic Angiopathies / genetics
  • Diabetic Angiopathies / pathology
  • Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Glucose / metabolism*
  • Interferon Regulatory Factor-1 / genetics
  • Interferon Regulatory Factor-1 / metabolism*
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / enzymology*
  • Muscle, Smooth, Vascular / pathology
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / enzymology*
  • Myocytes, Smooth Muscle / pathology
  • Protein Kinase Inhibitors / pharmacology
  • RNA Interference
  • Rats
  • Rats, Sprague-Dawley
  • Reactive Oxygen Species / metabolism*
  • Signal Transduction
  • Transfection
  • Up-Regulation

Substances

  • Antioxidants
  • Ccnd1 protein, rat
  • Cyclin E
  • Interferon Regulatory Factor-1
  • Irf1 protein, rat
  • Protein Kinase Inhibitors
  • Reactive Oxygen Species
  • Cyclin D1
  • Cdk2 protein, rat
  • Cdk4 protein, rat
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinase 4
  • Extracellular Signal-Regulated MAP Kinases
  • Glucose