Rho-kinase mediates hyperglycemia-induced plasminogen activator inhibitor-1 expression in vascular endothelial cells

Area of Science:

• Molecular biology
• Cardiovascular research
• Endocrinology

Background:

• Elevated plasminogen activator inhibitor-1 (PAI-1) is linked to myocardial infarction and stroke, particularly in diabetic patients.
• Hyperglycemia-induced PAI-1 expression involves oxidative stress and protein kinase C (PKC), but the precise mechanism remains unclear.

Purpose of the Study:

• To elucidate the mechanism by which hyperglycemia increases PAI-1 expression in human endothelial cells.
• To investigate the role of Rho-kinase in hyperglycemia-induced PAI-1 production.

Main Methods:

• Human endothelial cells were exposed to varying glucose concentrations.
• Rho-kinase activity and PAI-1 expression were measured.
• Inhibition studies utilized PKC inhibitors (GF109203X), antioxidants (N-acetylcysteine, reduced glutathione), and Rho-kinase inhibitors (hydroxyfasudil, Y27632).
• ROCK I-knockout murine endothelial cells were used to assess the role of ROCK I.

Main Results:

• Hyperglycemia, unlike mannitol, time- and concentration-dependently increased Rho-kinase activity.
• PKC inhibition and antioxidants (NAC, GSH) blocked this increase and subsequent PAI-1 expression.
• Rho-kinase inhibition and a dominant-negative Rho-kinase mutant significantly reduced hyperglycemia-induced PAI-1 mRNA and protein levels.
• Hyperglycemia failed to increase Rho-kinase activity or PAI-1 expression in ROCK I-knockout cells.

Conclusions:

• Hyperglycemia stimulates Rho-kinase activity through PKC and oxidative stress pathways, leading to increased PAI-1 gene transcription.
• Inhibition of Rho-kinase (ROCK I) presents a potential therapeutic strategy for preventing thromboembolic complications in diabetes and cardiovascular disease.