title: Polyomavirus small T antigen interacts with yes-associated protein to regulate cell survival and differentiation.
abstract: Murine polyomavirus small t antigen (PyST) regulates cell cycle, cell survival, apoptosis, and differentiation and cooperates with middle T antigen (MT) to transform primary cells in vitro and in vivo. Like all polyomavirus T antigens, PyST functions largely via its interactions with host cell proteins. Here, we show that PyST binds both Yes-associated protein 1 (YAP1) and YAP2, integral parts of the Hippo signaling pathway, which is a subject of increasing interest in human cancer. The transcription factor TEAD, which is a known target of YAP, is also found in PyST complexes. PyST enhanced YAP association with protein phosphatase 2A (PP2A), leading to decreased YAP phosphorylation. PyST increased YAP levels by decreasing its degradation. This effect was mediated by a reduction in YAP association with β-transducin repeat protein (βTRCP), which is known to regulate YAP turnover in a phosphorylation-dependent manner. Genetic analysis has identified PyST mutants defective in YAP binding. These mutants demonstrated that YAP binding is important for PyST to block myoblast differentiation and to synergize with the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX) to promote cell death in 3T3-L1 preadipocytes placed under differentiation conditions. In addition to YAP binding, both of these phenotypes require PyST binding to PP2A. Importance: The Hippo/YAP pathway is a highly conserved cascade important for tissue development and homeostasis. Defects in this pathway are increasingly being associated with cancer. Polyomavirus small t antigen is a viral oncogene that cooperates with middle T antigen in transformation. On its own, small t antigen controls cell survival and differentiation. By binding YAP, small t antigen brings it together with protein phosphatase 2A. This work shows how this association of small t antigen with YAP is important for its effects on cell phenotype. It also suggests that PyST can be used to characterize cellular processes that are regulated by YAP.
authors.affiliation: Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts, USA.
authors.forename: Justin H
authors.initials: JH
authors.lastname: Hwang
authors.affiliation: Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Arun T
authors.initials: AT
authors.lastname: Pores Fernando
authors.affiliation: Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Faure
authors.affiliation: Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA Department of Biochemistry, University of Kashmir, Kashmir, India.
authors.forename: Shaida
authors.initials: S
authors.lastname: Andrabi
authors.forename: Guillaume
authors.initials: G
authors.lastname: Adelmant
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors.forename: William C
authors.initials: WC
authors.lastname: Hahn
authors.forename: Jarrod A
authors.initials: JA
authors.lastname: Marto
authors.affiliation: Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts, USA brian.schaffhausen@tufts.edu thomas_roberts@dfci.harvard.edu.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Schaffhausen
authors.affiliation: Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA brian.schaffhausen@tufts.edu thomas_roberts@dfci.harvard.edu.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Roberts
mesh_terms: D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D002454:Cell Differentiation; D002470:Cell Survival; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000952:Antigens, Polyomavirus Transforming; D010750:Phosphoproteins; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins; C088374:YAP1 protein, human