Point mutational analysis of the human c-fos serum response factor binding site.

AUTOR(ES)

Leung, S

RESUMO

A series of point mutants were generated in the human c-fos dyad symmetry element (DSE), found within the c-fos serum response element, to study the sequence requirements for its interaction with the human HeLa cell serum response factor (SRF). Plasmids that contain base substitutions within a core CC(A/T)6GG motif in the center of the DSE did not compete, or competed very poorly, with the wild-type c-fos DSE for formation of a specific SRF-DSE complex in vitro. The CC(A/T)6GG motif is not sufficient for maximal binding of SRF, as several plasmids that contain base substitutions in the sequences flanking this core motif competed either poorer or better than the wild-type c-fos DSE for SRF binding. Evidence is presented that supports the idea that SRF binds in a symmetrical fashion. Results of in vivo transient expression assays in HeLa cells suggest that negative regulation of c-fos transcription observed in serum-deprived cells is mediated through SRF binding to the DSE.

Documentos Relacionados

• The sarcomeric actin CArG-binding factor is indistinguishable from the c-fos serum response factor.
• Xenopus cytoskeletal actin and human c-fos gene promoters share a conserved protein-binding site.
• Maximal serum stimulation of the c-fos serum response element requires both the serum response factor and a novel binding factor, SRE-binding protein.
• YY1 facilitates the association of serum response factor with the c-fos serum response element.
• Phosphorylation of serum response factor, a factor that binds to the serum response element of the c-FOS enhancer.