Growth arrest of a murine mesangial cell line by transforming growth factor β1 is associated with inhibition of mitogen-induced Ca²⁺ mobilization

Transforming growth factor-β (TGFβ) is a multifunctional cytokine showing growth effects on many cell types. In the present study effects of TGFβ1 on mitogen-induced Ca²⁺ responses were investigated in an immortalized murine mesangial cell line where TGFβ1 effects on growth are inhibitory. TGFβ1 was found to inhibit intracellular Ca²⁺ mobilization induced by platelet-derived growth factor (PDGF). This effect was completely reversed by previous addition of the non-specific serine/threonine kinase inhibitor H-7, but was unaffected by GF 109203X, a specific inhibitor of protein kinase C (PKC). These findings suggest that inhibition of mitogen-induced Ca²⁺ mobilization by TGFβ1 appears not to involve prior activation of PKC, but may participate in the mechanisms whereby mesangial cell growth is inhibited by TGFβ1.