Thrombin increases clusterin mRNA in glomerular epithelial and mesangial cells

Area of Science:

• Nephrology
• Molecular Biology
• Biochemistry

Background:

• Clusterin is a multifunctional protein found in the kidney during renal failure.
• Fibrin, a product of thrombin activity, is also present in the kidney.
• The influence of thrombin on clusterin mRNA in the kidney remains uncharacterized.

Purpose of the Study:

• To investigate the effect of thrombin on clusterin mRNA expression in various kidney cell types.
• To determine if thrombin receptor activation specifically regulates clusterin mRNA levels.
• To elucidate the signaling pathway involved in thrombin-mediated clusterin mRNA regulation.

Main Methods:

• Northern blot analysis was used to quantify clusterin mRNA levels.
• Experiments were conducted on rat glomerular mesangial cells, rat glomerular epithelial cells, and human renal proximal tubular epithelial cells.
• Specific thrombin receptor activating peptides and a protein kinase C inhibitor were utilized.

Main Results:

• Thrombin (10(-8) M) exposure resulted in a two- to fourfold increase in clusterin mRNA in all tested kidney cell types.
• Activation of the thrombin receptor by specific peptides mimicked thrombin's effect on clusterin mRNA.
• Epidermal growth factor, insulin-like growth factor-1, and transforming growth factor-beta 1 showed minimal impact on clusterin mRNA.
• The protein kinase C inhibitor RO-32-0432 blocked the thrombin-induced increase in clusterin mRNA.

Conclusions:

• Thrombin significantly upregulates clusterin mRNA expression in glomerular mesangial, glomerular epithelial, and proximal tubular epithelial cells.
• This upregulation is specifically mediated via thrombin receptor activation.
• Protein kinase C signaling appears to be a key pathway in thrombin's regulation of renal clusterin mRNA levels.