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Jiao Liu, Lili Gong, Mi Deng, Wei-Ke Ji, Jia-Han Lv, Shuming Sun, Lan Zhang, Pei-Qiao Chen, Wen-Feng Hu, David W. Li; Transcriptional Regulation of PP2A-Aβ Is Mediated by Multiple Transcription Factors. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2778. doi: https://doi.org/.
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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-Aα/β, 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-Aα/β 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-Aβ gene.
Western-blot analysis was conducted to detect the expression of ETS-1, SP-1 and RXRα/β in mouse lens epithelial cell line (αTN4-1) and human lens epithelial cell line (FHL-124). Gel mobility shifting assay was used to test the binding activities of ETS-1, SP-1 and RXRα/β to PP2A-Aβ gene promoter. In vitro mutagenesis and luciferase reporter gene activity assay was conducted to detect the transcriptional regulation of PP2A-Aβ gene promoter by these transcription factors. ChIP assay was used to further confirm the in vivo interactions between each of these transcription factors and PP2A-Aβ gene promoter.
ETS-1, SP-1 and RXRα/β all exist in αTN4-1 and FHL-124 cells. Gel mobility shifting assay and ChIP assay showed that three transcription factors displayed binding ability to the PP2A-Aβ gene promoter in vitro and in vivo. In vitro mutagenesis and luciferase reporter gene activity assay demonstrated that SP1 negatively regulates while ETS-1 and RXRα/β positively regulate the promoter of the PP2A-Aβ gene.
Transcriptional regulation of PP2A-Aβ is mediated by multiple factors including ETS-1, SP-1 and RXRα/β.
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