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- Title
Sin1 binds to both ATF-2 and p38 and enhances ATF-2-dependent transcription in an SAPK signaling pathway.
- Authors
Makino, Chieko; Sano, Yuji; Shinagawa, Toshie; Millar, Jonathan B A; Ishii, Shunsuke
- Abstract
Yeast Sin1 binds to the Sty1 kinase, a member of the stress-activated kinases (SAPKs), and is required for stress-induced phosphorylation and activation of the transcription factor Atf1, a homolog of the vertebrate-activating transcription factor-2 (ATF-2). Here we report that mammalian Sin1 plays an important role in the SAPK signaling pathway by binding to both ATF-2 and p38. In response to stress, ATF-2, a member of the ATF/cAMP response element-binding protein family, is phosphorylated by p38/Jun NH2-terminal protein kinase and activates the transcription of apoptosis-related genes. In contrast, in response to serum stimulation, ATF-2 is phosphorylated via the Ras effector pathway and leads to the induction of growth-related genes. We found that Sin1 binds directly to both ATF-2 and p38. Sin1 over-expression enhanced osmotic stress-induced phosphorylation of ATF-2 and ATF-2-mediated transcription, whereas knockdown of Sin1 expression by siRNA suppressed these responses. Moreover, a reduction in Sin1 expression suppressed osmotic stress-induced apoptosis and the expression of Gadd45beta, one of the ATF-2 target genes that is correlated with apoptosis. Decreased Sin1 expression, however, did not affect the serum stimulation-induced phosphorylation of ATF-2. Sin1 may contribute to ATF-2 signaling specificity by acting as a nuclear scaffold.
- Publication
Genes to cells : devoted to molecular & cellular mechanisms, 2006, Vol 11, Issue 11, p1239
- ISSN
1356-9597
- Publication type
Journal Article
- DOI
10.1111/j.1365-2443.2006.01016.x