A proline-rich TGF-beta-responsive transcriptional activator interacts with histone H3.
The molecular mechanisms involved in the regulation of gene expression by transforming growth factor-beta (TGF-beta) have been analyzed. We show that TGF-beta specifically induces the activity of the proline-rich trans-activation domain of CTF-1, a member of the CTF/NF-I family of transcription factors. A TGF-beta-responsive domain (TRD) in the proline-rich transcriptional activation sequence of CTF-1 was shown to mediate TGF-beta induction in NIH-3T3 cells. Mutagenesis studies indicated that this domain is not the primary target of regulatory phosphorylations, suggesting that the growth factor may regulate a CTF-1-interacting protein. A two-hybrid screening assay identified a nucleosome component, histone H3, as a specific CTF-1-interacting protein in yeast. Furthermore, the CTF-1 trans-activation domain was shown to interact with histone H3 in both transiently and stably transfected mammalian cells. This interaction requires the TRD, and it appears to be upregulated by TGF-beta in vivo. Moreover, point mutations in the TRD that inhibit TGF-beta induction also reduce interaction with histone H3. In vitro, the trans-activation domain of CTF-1 specifically contacts histone H3 and oligomers of histones H3 and H4, and full-length CTF-1 was shown to alter the interaction of reconstituted nucleosomal cores with DNA. Thus, the growth factor-regulated trans-activation domain of CTF-1 can interact with chromatin components through histone H3. These findings suggest that such interactions may regulate chromatin dynamics in response to growth factor signaling.
Institute of Animal Biology, University of Lausanne, Switzerland.
A
A
Alevizopoulos
Y
Y
Dusserre
M
M
Tsai-Pflugfelder
T
T
von der Weid
W
W
Wahli
N
N
Mermod
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002843:Chromatin / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005973:Glutamine / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors; D009707:Nucleosomes / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D017354:Point Mutation; D011392:Proline / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D022762:CCAAT-Enhancer-Binding Proteins; C077305:CTF-1 transcription factor; D002843:Chromatin; D004268:DNA-Binding Proteins; D006657:Histones; D051839:NFI Transcription Factors; D009707:Nucleosomes; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D005973:Glutamine; D011392:Proline