Role for transcription factor TFII-I in the suppression of SSeCKS/Gravin/Akap12 transcription by Src.
The SSeCKS/Gravin/AKAP12 gene, encoding a kinase scaffolding protein with metastasis-suppressing activity, is transcriptionally downregulated in Src-transformed cells through the recruitment of HDAC1 to a Src-responsive proximal promoter site charged with Sp1, Sp3 and USF1. However, the ectopic expression of these proteins formed a suppressive complex in Src-transformed but not in parental NIH3T3 cells, suggesting the involvement of additional repressor factors. Transcription factor II-I (TFII-I) [general transcription factor 2i (Gtf2i)] was identified by mass spectrometry as being associated with the SSeCKS promoter complex in NIH3T3/Src cells, and moreover, the Src-induced tyrosine phosphorylation of TFII-I significantly increased its binding to the SSeCKS proximal promoter. siRNA-mediated knockdown of TFII-I or the expression of TFII-I(Y248/249F) caused the derepression of SSeCKS in NIH3T3/Src cells. Taken with previous data showing that the tyrosine phosphorylation of TFII-I facilitates its nuclear translocation, these data suggest that Src-family kinase-mediated phosphorylation converts a portion of TFII-I into a transcriptional repressor.
Bu
Yahao
Y
Kinex Pharmaceuticals, LLC, Buffalo, NY, USA.
Gao
Lingqiu
L
Gelman
Irwin H
IH
D054758:A Kinase Anchor Proteins / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D002853:Chromatography, Liquid; D015536:Down-Regulation; D005786:Gene Expression Regulation; D047468:Immunoprecipitation; D051379:Mice; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D019473:Transcription Factors, TFII / Q000502:physiology*; D014158:Transcription, Genetic; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
D054758:A Kinase Anchor Proteins; C491161:Akap12 protein, mouse; D018797:Cell Cycle Proteins; C486330:Gtf2i protein, mouse; D012333:RNA, Messenger; D019473:Transcription Factors, TFII; D019061:src-Family Kinases