Region 752-761 of STAT3 is critical for SRC-1 recruitment and Ser727 phosphorylation.
STAT3 regulates many target genes in response to cytokines and growth factors. To study the mechanisms of STAT3-dependent transcription, we established several cell lines in which HepG2-STAT3-knockdown cells were reconstituted with a variety of STAT3 mutants. Using these cell lines, we found that truncated STAT3(1-750), but not STAT3(1-761), could not recruit SRC-1/NcoA-1 and was not phosphorylated on Ser727. Furthermore, mutation of STAT3 L755 and F757 to alanines caused the loss of STAT3-dependent SRC-1 recruitment, leaving Ser727 phosphorylation intact. Consistent with this, the STAT3-L755A/F757A mutant showed no increase in acetylated histone H3 at Lys14 and a decreased level of RNA polymerase II recruited to the target gene promoter, although p300 recruitment and histone H4 acetylation were intact. This mutant also lost responsiveness to co-expressed SRC-1. Thus, the conserved STAT3 region from 752 to 761, called STAT3 CR2, plays critical roles in STAT3-dependent transcription by recruiting SRC-1 and allowing Ser727 phosphorylation.
Zhao
Hong
H
Department of Immunology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
Nakajima
Ryota
R
Kunimoto
Hiroyuki
H
Sasaki
Takanori
T
Kojima
Hirotada
H
Nakajima
Koichi
K
D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D050881:E1A-Associated p300 Protein; D015870:Gene Expression / Q000502:physiology; D051548:Histone Acetyltransferases; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D007930:Leucine / Q000235:genetics / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism; D056920:Nuclear Receptor Coactivator 1; D010649:Phenylalanine / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000502:physiology; D017434:Protein Structure, Tertiary; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050796:STAT3 Transcription Factor; D012694:Serine / Q000378:metabolism*; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology
D004268:DNA-Binding Proteins; D015850:Interleukin-6; D009687:Nuclear Proteins; D016755:Proto-Oncogene Proteins c-jun; D011993:Recombinant Fusion Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D012694:Serine; D010649:Phenylalanine; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse; D051548:Histone Acetyltransferases; C538859:NCOA1 protein, human; C538861:Ncoa1 protein, mouse; D056920:Nuclear Receptor Coactivator 1; D007930:Leucine