The function of PP2A/B56 in non-metazoan multicellular development

Lee, Nam-Sihk; Veeranki, Sudhakar; Kim, Bohye; Kim, Leung

doi:10.1111/j.1432-0436.2008.00301.x

Cited by 13 publications

(21 citation statements)

References 17 publications

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“…PP2A activity was measured by release of phosphates from phosphopeptides (K-R-pT-I-R-R) using a Malachite Green assay (PP2A immunoprecipitation phosphatase assay kit; Millipore) as previously described (Lee et al , 2008). The activity was normalized to cell numbers.…”

Section: Methodsmentioning

confidence: 99%

Dictyostelium huntingtin controls chemotaxis and cytokinesis through the regulation of myosin II phosphorylation

Wang

Steimle

Ren

et al. 2011

MBoC

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Section: Methodsmentioning

confidence: 99%

Dictyostelium huntingtin controls chemotaxis and cytokinesis through the regulation of myosin II phosphorylation

Wang

Steimle

Ren

et al. 2011

MBoC

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“…Recent studies resolving the structure of the PP2A/B56 holoenzyme indicate that the carboxyl side of B56 could partially block the active site of the PP2A catalytic subunit P2Ac (3,21). Likewise, other regulatory subunits could also affect the phosphatase activity, either positively or negatively, in addition to their roles of substrate interaction and subcellular localization of the PP2A holoenzyme (14). In this study, we described the role of the PP2A regulatory subunit in myosin II assembly in Dictyostelium.…”

mentioning

confidence: 90%

Role of B Regulatory Subunits of Protein Phosphatase Type 2A in Myosin II Assembly Control in Dictyostelium discoideum

Rai

Egelhoff

2011

Eukaryot Cell

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In Dictyostelium discoideum, myosin II resides predominantly in a soluble pool as the result of phosphorylation of the myosin heavy chain (MHC), and dephosphorylation of the MHC is required for myosin II filament assembly, recruitment to the cytoskeleton, and force production. Protein phosphatase type 2A (PP2A) was identified in earlier studies in Dictyostelium as a key biochemical activity that can drive MHC dephosphorylation. We report here gene targeting and cell biological studies addressing the roles of candidate PP2A B regulatory subunits (phr2aB␣ and phr2aB␤) in myosin II assembly control in vivo. Dictyostelium phr2aB␣-and phr2aB␤-null cells show delayed development, reduction in the assembly of myosin II in cytoskeletal ghost assays, and defects in cytokinesis when grown in suspension compared to parental cell lines. These results demonstrate that the PP2A B subunits phr2aB␣ and phr2aB␤ contribute to myosin II assembly control in vivo, with phr2aB␣ having the predominant role facilitating MHC dephosphorylation to facilitate filament assembly.Myosin II plays critical roles in cytokinesis, cortical tension maintenance, cell migration, and multicellular development in Dictyostelium discoideum cells. In vivo myosin II function requires assembly into bipolar filaments, allowing interaction with cortical actin and force production. In resting Dictyostelium cells, a majority of the cell's myosin II resides in a soluble cytosolic pool, which is rapidly assembled into cytoskeletal bipolar filaments during cell motility in response to chemotactic stimuli (1). Phosphorylation of three threonine residues at positions 1823, 1833, and 2029 of the MHC regulates filament assembly and localization of myosin, with phosphorylation driving filament disassembly (5, 7). Dephosphorylation is necessary for filament assembly in vitro and in vivo, and exchange between the assembled and soluble pools in live cells is remarkably rapid, with a half-life (t 1/2 ) of ϳ7 s in live cells (22,23). A series of three MHC kinases (MHCK A, MHCK B, and MHCK C) were identified in previous work and were demonstrated to mediate filament disassembly in live cells (13,23).Although the MHCKs that mediate in vivo assembly control have been established, protein phosphatases involved in assembly control have not been well studied. Murphy and Egelhoff reported PP2A as a major MHC phosphatase in Dictyostelium in studies using purified myosin II and biochemical fractionation approaches (16). In those studies, PP2A holoenzyme displayed substantially higher activity toward myosin phosphorylated on the heavy chains than it did toward myosin phosphorylated on the regulatory light chains (RLC), supporting the hypothesis that PP2A may have a physiological role in the control of filament assembly (16).The heterotrimeric PP2A holoenzyme is a highly conserved regulatory system in diverse eukaryotes. The core PP2A consists of an ϳ36-kDa catalytic subunit (pho2A) tightly associated with a 65-kDa scaffolding A subunit (pppA), forming an AC dimer which then associate...

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“…Also, in chapter 3, the role of the PP2A regulatory subunit, B56, in PKBR1 adaption will be discussed. It was suggested that B56 negatively regulate PP2A catalytic activity in mammalian cells and in Dictyostelium cells because cells lacking B56 exhibited persistent phosphorylation of PP2A substrates (Ito, A. et al 2000;Lee, N. et al 2008).…”

Section: The Family Of Small Gtpases Ras Regulates Leading Edge Formamentioning

confidence: 99%

“…et al 1995;Kim, L. et al 2000;Kim, L. et al 2002;Schilde, C. et al 2004;Lee, N. et al 2008). In addition, PP2A/B56 was shown to regulate cell fate determination modulating GSK3 activity; psrA -cells exhibited abnormally high levels of active GSK3 and delayed expression of pre-stalk cell markers, Extracellular Matrix proteins A and B (ecmA and ecmB), and high expression of prespore cell markers, Spore Coat protein B (cotB) .…”

Section: Gsk3 Regulates Pkbr1 Activationmentioning

confidence: 99%

“…Previously, the PP2A catalytic subunit was found to interact with the Sca1 complex regulating Sca1-mediated RasC activation; Sca1 mutants lacking the region in which PP2A interacts with Sca1 failed to activate RasC suggesting PP2A is necessary for Sca1-mediated RasC activation . The PP2A regulatory subunits have been shown to regulate the phosphatase activity, cellular localization, and/or substrate specificity of the PP2A complex Cho, U. S. and Xu, W. 2006;Lee, N. et al 2008;Virshup, D.M. and Shenolikar, S. 2009); in the absence of B56, the Sca1 complex may encounter localization problems.…”

Section: Mpl1 Plays An Essential Role In Erk2 Adaptationmentioning

confidence: 99%

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Two Adaptation Mechanisms Regulate Cellular Migration in Dictyostelium discouideum

Rodriguez¹

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The function of PP2A/B56 in non-metazoan multicellular development

Cited by 13 publications

References 17 publications

Dictyostelium huntingtin controls chemotaxis and cytokinesis through the regulation of myosin II phosphorylation

Dictyostelium huntingtin controls chemotaxis and cytokinesis through the regulation of myosin II phosphorylation

Role of B Regulatory Subunits of Protein Phosphatase Type 2A in Myosin II Assembly Control in Dictyostelium discoideum

Two Adaptation Mechanisms Regulate Cellular Migration in Dictyostelium discouideum

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