Open AccessCell-type specific multiprotein complex formation over the c-fosserum response elementin vivo: ternary complex formation is not required for the induction of c-fos
Author(s) -
Harald König
Publication year - 1991
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/19.13.3607
Subject(s) - serum response element , serum response factor , biology , ternary complex , microbiology and biotechnology , transcription factor , 3t3 cells , c fos , in vivo , footprinting , cell culture , gene expression , gene , biochemistry , transfection , genetics , enzyme
At the serum response element (SRE) of the c-fos proto-oncogene a ternary complex with two proteins, ternary complex factor (p62TCF) and serum response factor (SRF) can be formed. Its formation has previously been suggested to be necessary for efficient induction of c-fos transcription by serum in mouse NIH 3T3 fibroblasts (1) and by phorbol esters, but not by serum, in mouse BALB/c 3T3 fibroblasts (2). It is shown here by genomic dimethyl sulfate (DMS) footprinting that this ternary complex is indeed formed in NIH 3T3 cells in vivo. However, cells were found, murine F9 teratocarcinoma stem cells, in which the pattern of protection and hyperreactivity is consistent with the absence of p62TCF in the protein complex in vivo, although inducibility of the endogenous c-fos gene is not impaired. Both in NIH 3T3 cells and in F9 cells a mutated c-fos promoter that binds SRF but fails to form a ternary complex, was inducible by serum and phorbol esters to the same extent as the wild-type promoter. The data suggest that ternary complex formation is not an absolute prerequisite for the transient induction of c-fos. Ternary complex formation rather appears to enhance overall promoter efficiency. A cell type specific component determines the formation of the multicomponent transcription factor complex in vivo.