Mechanisms of endothelin-1 mRNA and peptides induction by TGF-β and TPA in MDCK cells

Mechanisms of prepro-ET-1 mRNA expression and mature endothelin-1 (ET-1) peptide secretion in MDCK cells (dog collecting duct origin) were investigated. MDCK cells constitutively expressed prepro-ET-1 mRNA (˜2.3 kb). TGF-β time-dependently increased prepro-ET-1 mRNA levels between 30 min and 6 h. Induction of the mRNA 6 h following TGF-β addition was dose-dependent with a half-maximal concentration of 10 pM. The half-life of prepro-ET-1 mRNA was 15 min in controls when the cells were treated with 10 μg/ml of actinomycin D, whereas it was extended to 30-45 min by TGF-β treatment. Prepro-ET-1 mRNA was rapidly (15-30 min) induced by 0.5 μM TPA. one of the phorbol esters, but downregulated below baseline after 1 h. Our data show that MDCK cells constitutively secrete ET-1 and increase its production in response to TGF-β. An axis of TGF-P-ET-1-collecting duct may play an important role in regulation of electrolyte transport and cell growth of the renal tubules.