Effects and Interactions of Endothelin-1 and Angiotensin II on Matrix Protein Expression and Synthesis and Mesangial Cell Growth
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Abstract Mesangial cell growth and accumulation of extracellular matrix proteins constitute key features of progressive glomerular injury. Endothelin-1 (ET-1) and angiotensin II (Ang II), two potent vasoconstrictor agents, evoke a number of similar responses in mesangial cells. In rat mesangial cells, we compared ET-1 and Ang II effects on matrix protein production and cell proliferation as well as the potential interaction between the two hormones. When cells in 0.5% fetal calf serum were incubated for 24 hours with various concentrations of ET-1 or Ang II, both peptides stimulated, in a dose-dependent manner, fibronectin and type IV collagen mRNA expression, fibronectin synthesis, and mitogenesis. Incubation with specific receptor antagonists of both hormones demonstrated that endothelin subtype A (ETA) and angiotensin type 1 (AT1) receptors were involved. Preincubation of cells with two different protein kinase C inhibitors or with a neutralizing anti–transforming growth factor-β antibody, but not an unrelated IgG, diminished the peptide-induced fibronectin synthesis. A dual interrelation seems to exist between ET-1 and Ang II. Thus, the AT1 receptor antagonist losartan and the angiotensin-converting enzyme inhibitors quinaprilat and captopril diminished the ET-1–mediated effects, whereas the ETA receptor antagonist BQ-123 diminished the Ang II–induced fibronectin synthesis and mesangial cell proliferation. Our results suggest that ET-1 and Ang II stimulate matrix protein synthesis and mesangial cell mitogenesis through ETA and AT1 receptors, respectively, by complicated mechanisms, implicating protein kinase C activation, synthesis of transforming growth factor-β, and release of one peptide by the other. These data could be important for a better understanding of the participation of vasoactive substances in the pathogenesis of glomerulosclerosis.
- angiotensin II
- mesangial cells
- matrix proteins
- protein kinases
- transforming growth factors
- angiotensin-converting enzyme inhibitors
- Received June 26, 1995.
- Revision received August 29, 1995.
- Accepted January 8, 1996.