title: The Tap42-protein phosphatase type 2A catalytic subunit complex is required for cell cycle-dependent distribution of actin in yeast.
abstract: In Saccharomyces cerevisiae, the Tor proteins mediate a wide spectrum of growth-related cellular processes in response to nutrients. The pleiotropic role of the Tor proteins is mediated, at least in part, by type 2A protein phosphatases (PP2A) and 2A-like protein phosphatases. Tor-mediated signaling activity promotes the interaction of phosphatase-interacting protein Tap42 with PP2A and 2A-like protein phosphatases. The distinct complexes formed between Tap42 and different phosphatases mediate various cellular events and modulate phosphorylation levels of many downstream factors in the Tor pathway in a Tor-dependent and rapamycin-sensitive manner. In this study, we demonstrate that the interaction between Tap42 and the catalytic subunits of PP2A (PP2Ac) is required for cell cycle-dependent distribution of actin. We show that mutations in PP2Ac and Tap42 that perturb the interaction cause random distribution of actin during the cell cycle and that overexpression of the Rho2 GTPase suppresses the actin defects associated with the mutants. Our findings suggest that the Tap42-PP2Ac complex regulates the actin cytoskeleton via a Rho GTPase-dependent mechanism. In addition, we provide evidence that PP2A activity plays a negative role in controlling the actin cytoskeleton and, possibly, in regulation of the G(2)/M transition of the cell cycle.
authors.affiliation: Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Huamin
authors.initials: H
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D020134:Catalytic Domain; D002453:Cell Cycle / Q000502:physiology*; D016764:Cell Polarity; D003599:Cytoskeleton / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D046911:Macromolecular Substances; D020559:Monomeric GTP-Binding Proteins; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D020123:Sirolimus / Q000494:pharmacology; D020741:rho GTP-Binding Proteins
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D046911:Macromolecular Substances; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C100984:TAP42 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D020559:Monomeric GTP-Binding Proteins; C051303:RHO2 protein, S cerevisiae; D020741:rho GTP-Binding Proteins; D020123:Sirolimus