Glucose upregulates plasminogen activator inhibitor-1 gene expression in vascular smooth muscle cells

Area of Science:

• Molecular Biology
• Cell Biology
• Endocrinology

Background:

• Elevated levels of plasminogen activator inhibitor-1 (PAI-1) are associated with diabetes and atherosclerosis.
• Vascular smooth muscle cells (VSMC) play a critical role in vascular health and disease.
• Understanding the regulation of PAI-1 expression in VSMC is crucial for addressing diabetes complications.

Purpose of the Study:

• To investigate the impact of high glucose concentrations on PAI-1 gene expression in cultured rat VSMC.
• To elucidate the signaling pathways involved in glucose-induced PAI-1 expression.

Main Methods:

• Cultured rat VSMC were exposed to high glucose concentrations (27.5 mM).
• Mannose was used as an osmotic control.
• PAI-1 mRNA levels were measured over time.
• The roles of mitogen-activated protein kinase (MAPK) and protein kinase C (PKC) pathways were assessed using specific inhibitors (PD98059 and GF109203X, respectively) and by monitoring transcription factor activation (Elk-1 and AP-1).

Main Results:

• High glucose significantly increased PAI-1 mRNA expression in VSMC, with effects observed within 2 hours and peaking at 4 hours.
• Mannose did not induce significant changes in PAI-1 mRNA levels, indicating the effect was glucose-specific and not due to osmotic changes.
• High glucose activated MAPK and PKC signaling pathways, as evidenced by Elk-1 and AP-1 activation.
• Inhibition of MAPK (PD98059) or PKC (GF109203X) reversed or prevented glucose-induced PAI-1 expression.

Conclusions:

• High glucose concentrations directly induce PAI-1 gene expression in VSMC.
• This induction is, at least partially, mediated through the activation of MAPK and PKC signaling pathways.
• These findings suggest a direct molecular mechanism linking hyperglycemia in diabetes to increased PAI-1 levels and potentially to the development of atherosclerosis.