Transcriptional Regulation of PP2A-Aα Is Mediated by Multiple Factors Including AP-2α, CREB, ETS-1, and SP-1

Protein phosphatases-2A (PP-2A) is a major serine/threonine phosphatase and accounts for more than 50% serine/threonine phosphatase activity in eukaryotes. The holoenzyme of PP-2A consists of the scaffold A subunit, the catalytic C subunit and the regulatory B subunit. The scaffold subunits, PP2A-A alpha/beta, provide a platform for both C and B subunits to bind, thus playing a crucial role in providing specific PP-2A activity. Mutation of the two genes encoding PP2A-A alpha/beta leads to carcinogenesis and likely other human diseases. Regulation of these genes by various factors, both extracellular and intracellular, remains largely unknown. In the present study, we have conducted functional dissection of the promoter of the mouse PP2A-A alpha gene. Our results demonstrate that the proximal promoter of the mouse PP2A-A alpha gene contains numerous cis-elements for the binding of CREB, ETS-1, AP-2 alpha, SP-1 besides the putative TFIIB binding site (BRE) and the downstream promoter element (DPE). Gel mobility shifting assays revealed that CREB, ETS-1, AP-2 alpha, and SP-1 all bind to PP2A-A alpha gene promoter. In vitro mutagenesis and reporter gene activity assays reveal that while SP-1 displays negative regulation, CREB, ETS-1 and AP-2A alpha all positively regulate the promoter of the PP2A-A alpha gene. ChIP assays further confirm that all the above transcription factors participate the regulation of PP2A-A alpha gene promoter. Together, our results reveal that multiple transcription factors regulate the PP2A-A alpha gene.