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

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)21567-21580
Number of pages14
JournalJournal of Biological Chemistry
Volume285
Issue number28
DOIs
Publication statusPublished - 2010 Jul 9

Fingerprint

Protein Phosphatase 2
Phosphoprotein Phosphatases
S Phase
Cell Cycle
Cells
Cell proliferation
Cell Proliferation
Tumor Suppressor Proteins
Holoenzymes
Phosphorylation
Substrate Specificity
HeLa Cells
Scaffolds
Tumors
Catalytic Domain
Proteins
Controllers
Substrates
Enzymes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Lee, Ting Yuan ; Lai, Tai Yu ; Lin, Shin Chih ; Wu, Cheng Wei ; Ni, In Fan ; Yang, Yu San ; Hung, Liang Yi ; Law, Brian K. ; Chiang, Chi Wu. / The B56γ3 regulatory subunit of protein phosphatase 2A (PP2A) regulates S phase-specific nuclear accumulation of PP2A and the G1 to S transition. In: Journal of Biological Chemistry. 2010 ; Vol. 285, No. 28. pp. 21567-21580.
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The B56γ3 regulatory subunit of protein phosphatase 2A (PP2A) regulates S phase-specific nuclear accumulation of PP2A and the G1 to S transition. / Lee, Ting Yuan; Lai, Tai Yu; Lin, Shin Chih; Wu, Cheng Wei; Ni, In Fan; Yang, Yu San; Hung, Liang Yi; Law, Brian K.; Chiang, Chi Wu.

In: Journal of Biological Chemistry, Vol. 285, No. 28, 09.07.2010, p. 21567-21580.

Research output: Contribution to journalArticle

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T1 - The B56γ3 regulatory subunit of protein phosphatase 2A (PP2A) regulates S phase-specific nuclear accumulation of PP2A and the G1 to S transition

AU - Lee, Ting Yuan

AU - Lai, Tai Yu

AU - Lin, Shin Chih

AU - Wu, Cheng Wei

AU - Ni, In Fan

AU - Yang, Yu San

AU - Hung, Liang Yi

AU - Law, Brian K.

AU - Chiang, Chi Wu

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N2 - 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.

AB - 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.

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