The B56γ3 regulatory subunit of protein phosphatase 2A (PP2A) regulates S phase-specific nuclear accumulation of PP2A and the G1 to S transition

Ting Yuan Lee, Tai Yu Lai, Shin Chih Lin, Cheng Wei Wu, In Fan Ni, Yu San Yang, Liang Yi Hung, Brian K. Law, Chi Wu Chiang

研究成果: Article同行評審

35 引文 斯高帕斯(Scopus)

摘要

Protein phosphatase 2A (PP2A) is a heterotrimeric enzyme consisting of a scaffold subunit (A), a catalytic subunit (C), and a variable regulatory subunit (B). The regulatoryBsubunits determine the substrate specificity and subcellular localization of the PP2A holoenzyme. Here, we demonstrate that the subcellular localization of the B56γ3 regulatory subunit is regulated in a cell cycle-specific manner. Notably, B56γ3 becomes enriched in the nucleus at the G1/S border and in S phase. The S phase-specific nuclear enrichment of B56γ3 is accompanied by increases of nuclear A and C subunits and nuclear PP2A activity. Overexpression of B56γ3 promotes nuclear localization of the A and C subunits, whereas silencing both B56γ2 and B56γ3 blocks the S phase-specific increase in the nuclear localization and activity of PP2A. In NIH3T3 cells, B56γ3 overexpression reduces p27 phosphorylation at Thr-187, concomitantly elevates p27 protein levels, delays the G1 to S transition, and retards cell proliferation. Consistently, knockdown of endogenous B56γ3 expression reduces p27 protein levels and increases cell proliferation in HeLa cells. These findings demonstrate that the dynamic nuclear distribution of the B56γ3 regulatory subunit controls nuclear PP2A activity, which regulates cell cycle controllers, such as p27, to restrain cell cycle progression, and may be responsible for the tumor suppressor function of PP2A.

原文English
頁(從 - 到)21567-21580
頁數14
期刊Journal of Biological Chemistry
285
發行號28
DOIs
出版狀態Published - 2010 7月 9

All Science Journal Classification (ASJC) codes

  • 生物化學
  • 分子生物學
  • 細胞生物學

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