期刊
CELL CYCLE
卷 8, 期 1, 页码 115-124出版社
TAYLOR & FRANCIS INC
DOI: 10.4161/cc.8.1.7527
关键词
p27(Kip1); histone deacetylase; platelet-derived growth factor; c-Myc; trichostatin A
类别
资金
- Cortner-Couch Endowed Chair for Cancer Research
- NIH [CA93544, CA67360]
How mitogens reduce the abundance of the cell cycle inhibitor p27(Kip1) is an important question, and regulation of p27(Kip1) translation and turnover has been described. Here we show that platelet-derived growth factor (PDGF) reduces the activity of the p27(Kip1) promoter and the abundance of the p27(Kip1) transcript in density-arrested mouse fibroblasts. Inhibition of p27(Kip1) gene expression by PDGF required protein synthesis and histone deacetylase activity but not Akt or ERK activity. PDGF increased the expression of c-Myc in the absence but not presence of a histone deacetylase inhibitor, and c-Myc inhibited p27(Kip1) promoter activity when ectopically expressed in fibroblasts. c-Myc targeted the same region of the p27(Kip1) promoter as did PDGF (deletion analysis) and interacted with this region in vivo (chromatin immunoprecipitation assay). Collectively, these findings suggest that c-Myc mediates the inhibitory effects of PDGF on the p27(Kip1) promoter. We also demonstrate reductions in p27(Kip1) mRNA abundance in primary splenocytes exposed to concanavalin A and in T cells exposed to interleukin-2 (IL-2). In contrast to PDGF in fibroblasts, IL-2 required Akt activity for maximal reductions in p27(Kip1) promoter activity and mRNA abundance in T cells. Thus, mitogens repress p27(Kip1) gene transcription in multiple systems and by multiple mechanisms.
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