Thrombin stimulation of renal cells

Area of Science:

• Nephrology
• Cell Biology
• Biochemistry

Background:

• Glomerular and vascular nephritides involve fibrin deposition in the kidney.
• Thrombin, a key enzyme in fibrin formation, influences cellular functions via its receptor.

Purpose of the Study:

• To investigate the presence and role of the functional thrombin receptor in the human kidney.
• To determine thrombin's effects on glomerular cells, including proliferation and synthesis of related proteins.

Main Methods:

• Immunohistochemistry and in situ hybridization to detect receptor expression in kidney tissue.
• Cell culture studies with glomerular epithelial and mesangial cells.
• Monoclonal antibody binding and Northern blot analysis for receptor confirmation.
• Assays to measure protein kinase C activation, intracellular calcium, and plasminogen activator synthesis.

Main Results:

• Constitutive expression of the functional thrombin receptor was confirmed in normal human kidneys and cultured glomerular cells.
• Thrombin demonstrated a potent mitogenic effect on cultured glomerular cells.
• Thrombin upregulated the synthesis of plasminogen activators and their type 1 inhibitor.
• Thrombin induced protein kinase C activation and increased intracellular calcium.
• Receptor internalization was observed following thrombin and phorbol myristate acetate stimulation.

Conclusions:

• The functional thrombin receptor is constitutively expressed in the human kidney.
• Thrombin signaling through its receptor contributes to glomerular cell proliferation and modulates the synthesis of key proteins involved in fibrinolysis.
• These findings suggest thrombin plays a significant role in the pathogenesis of glomerular diseases.