Serum Response Factor-GATA Ternary Complex Required for Nuclear Signaling by a G-Protein-Coupled Receptor

Abstract

Endothelins are a family of biologically active peptides that are critical for development and function of neural crest-derived and cardiovascular cells. These effects are mediated by two G-protein-coupled receptors and involve transcriptional regulation of growth-responsive and/or tissue-specific genes. We have used the cardiac ANF promoter, which represents the best-studied tissue-specific endothelin target, to elucidate the nuclear pathways responsible for the transcriptional effects of endothelins. We found that cardiac-specific response to endothelin 1 (ET-1) requires the combined action of the serum response factor (SRF) and the tissue-restricted GATA proteins which bind over their adjacent sites, within a 30-bp ET-1 response element. We show that SRF and GATA proteins form a novel ternary complex reminiscent of the well-characterized SRF-ternary complex factor interaction required for transcriptional induction of c-fos in response to growth factors. In transient cotransfections, GATA factors and SRF synergistically activate atrial natriuretic factor and other ET-1-inducible promoters that contain both GATA and SRF binding sites. Thus, GATA factors may represent a new class of tissue-specific SRF accessory factors that account for muscle- and other cell-specific SRF actions.

ACKNOWLEDGMENTS

We are grateful to Brian Wilkes for molecular modeling studies, to Lynda Robitaille for technical assistance, to Lise Laroche for secretarial help, and to members of the Nemer lab for helpful discussions.

This work was supported by grants from the Medical Research Council of Canada (MT-13056 and MOP-36382) and in part by a grant from the Société de recherches sur le cancer inc. S.M. was the recipient of an MRC studentship, and M.N. is a senior Scientist of the MRC.

The first two authors contributed equally to this work.