Transcriptional regulation of the Grp78 promoter by endoplasmic reticulum stress: role of TFII-I and its tyrosine phosphorylation.
TFII-I is a signal-induced multi-functional transcription factor that has recently been implicated as a regulatory component of the endoplasmic reticulum (ER) stress response. TFII-I acts through ER stress-induced binding to the ER stress element, which is highly conserved in promoters of ER stress-inducible genes such as Grp78/BiP. Interestingly, its tyrosine phosphorylation sites are required for its activation of the Grp78 promoter. Toward understanding the link between TFII-I, the tyrosine kinase signaling pathway, and Grp78 activation, we discovered that Tg stress induces a dramatic increase of TFII-I phosphorylation at Tyr248 and localization of this form of TFII-I to the nucleus. Chromatin immunoprecipitation analysis further reveals enhanced TFII-I binding to the Grp78 promoter in vivo upon ER stress. Previously, we reported that genistein, a general inhibitor of tyrosine kinase, could suppress ER stress induction of Grp78 by inhibiting complex formation on the ER stress element; however, the mechanism is not known. Consistent with TFII-I being a target of genistein suppression, we observed that genistein could suppress Tg stress-induced phosphorylation of TFII-I. We further demonstrate that c-Src, which is one of kinases identified to mediate phosphorylation of TFII-I at Tyr248, is activated by Tg stress and is able to stimulate the Grp78 promoter activity. Lastly, using stable cell lines with suppressed TFII-I levels, we show that TFII-I is required for optimal induction of Grp78 by ER stress. Our studies provide a molecular link that connects the c-Src tyrosine kinase transduction pathway to ER stress-induced transcriptional activation of Grp78 mediated by TFII-I.
Hong
Min
M
Department of Biochemistry and Molecular Biology and the University of Southern California/Norris Comprehensive Cancer Center, Keck School of Medicine of the University of Southern California, Los Angeles, California 90089-9176, USA.
Lin
Meng-yin
MY
Huang
Jen-ming
JM
Baumeister
Peter
P
Hakre
Shweta
S
Roy
Ananda L
AL
Lee
Amy S
AS
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D000081247:CSK Tyrosine-Protein Kinase; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D017930:Genes, Reporter; D019833:Genistein / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D051379:Mice; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008957:Models, Genetic; D018832:Molecular Chaperones / Q000378:metabolism / Q000502:physiology*; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D019473:Transcription Factors, TFII / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism*; D019061:src-Family Kinases
D000091342:Endoplasmic Reticulum Chaperone BiP; C104259:GTF2I protein, human; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D018832:Molecular Chaperones; D019473:Transcription Factors, TFII; D014443:Tyrosine; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human