L-type voltage-sensitive calcium channel activation stimulates gene expression by a serum response factor-dependent pathway

A mechanism by which calcium-induced signals are transduced to the nucleus to activate transcription of the c-fos proto-oncogene has been characterized. The serum response element (SRE), a region of the c-fos gene which controls growth factor-induced transcription, is now shown to mediate c-fos transcription in response to activation of L-type voltage-sensitive calcium channels. Calcium-dependent transcriptional activation through the SRE is mediated by the serum response factor (SRF). Membrane depolarization induces phosphorylation of SRF at Ser-103, an event shown to enhance the ability of SRF to bind the SRE. Ca²⁺-induced SRF phosphorylation occurs via a pathway that may involve Ca²⁺/calmodulin-dependent kinases.