1. Rac1 and a GTPase-activating protein, MgcRacGAP, are required for nuclear translocation of STAT transcription factors
- Author
-
Kawashima, Toshiyuki, Bao, Ying Chun, Nomura, Yasushi, Moon, Yuseok, Tonozuka, Yukio, Minoshima, Yukinori, Hatori, Tomonori, Tsuchiya, Akiho, Kiyono, Mari, Nosaka, Tetsuya, Nakajima, Hideaki, Williams, David A., and Kitamura, Toshio
- Subjects
Gene expression -- Analysis ,Proteins -- Properties ,Molecular chaperones -- Genetic aspects ,Biological sciences - Abstract
STAT transcription factors are tyrosine phosphorylated upon cytokine stimulation and enter the nucleus to activate target genes. We show that Rac1 and a GTPase-activating protein, MgcRacGAP, bind directly to p-STAT5A and are required to promote its nuclear translocation. Using permeabilized cells, we find that nuclear translocation of purified p-STAT5A is dependent on the addition of GTP-bound Rac1, MgcRacGAP, importin [alpha], and importin [beta]. p-STAT3 also enters the nucleus via this transport machinery, and mutant STATs lacking the MgcRacGAP binding site do not enter the nucleus even after phosphorylation. We conclude that GTP-bound Rac1 and MgcRacGAP function as a nuclear transport chaperone for activated STATs.
- Published
- 2006