title: Repression of Smad transcriptional activity by PIASy, an inhibitor of activated STAT.
abstract: Smad proteins mediate transforming growth factor beta (TGF-beta)-inducible transcriptional responses. Protein inhibitor of activated signal transducer and activator of transcription (PIAS) represents a family of proteins that inhibits signal transducer and activator of transcription and also regulates other transcriptional responses. In an effort to identify Smad-interacting proteins by a yeast three-hybrid screen with Smad3 and Smad4 as baits, we identified PIASy, a member of the PIAS family. In yeast, PIASy interacts strongly with Smad4 and also with receptor-regulated Smads. In mammalian cells, PIASy binds most strongly with Smad3 and also associates with other receptor-regulated Smads and Smad4. The interaction between Smad3 and PIASy is increased in the presence of TGF-beta and occurs through the C-terminal domain of Smad3. Moreover, Smad3, Smad4, and PIASy can form a ternary complex. PIASy does not inhibit Smad complex binding to DNA, but it represses Smad transcriptional activity. Interestingly, conditional overexpression of PIASy selectively inhibits a subset of endogenous TGF-beta-responsive genes, which includes the cyclin-dependent kinase inhibitor p15, and the plasminogen activator inhibitor 1. We further show that PIASy can interact constitutively with histone deacetylase 1 (HDAC1) and that addition of HDAC inhibitor trichostatin A (TSA) can prevent the inhibitory function of PIASy. Taken together, our studies indicate that PIASy can inhibit TGF-beta/Smad transcriptional responses through interactions with Smad proteins and HDAC.
authors.affiliation: Center for Advanced Biotechnology and Medicine, Susan Lehman Cullman Laboratory for Cancer Research, Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, State University of New Jersey, 679 Hoes Lane, Piscataway, NJ 08854, USA.
authors.forename: Jianyin
authors.initials: J
authors.lastname: Long
authors.forename: Isao
authors.initials: I
authors.lastname: Matsuura
authors.forename: Dongming
authors.initials: D
authors.lastname: He
authors.forename: Guannan
authors.initials: G
authors.lastname: Wang
authors.forename: Ke
authors.initials: K
authors.lastname: Shuai
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
mesh_terms: D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D051379:Mice; D000075223:Poly-ADP-Ribose Binding Proteins; D050828:Protein Inhibitors of Activated STAT; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051785:Smad Proteins; D051900:Smad3 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; C485891:PIAS4 protein, human; D000075223:Poly-ADP-Ribose Binding Proteins; D050828:Protein Inhibitors of Activated STAT; D011993:Recombinant Fusion Proteins; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human; D051785:Smad Proteins; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D015534:Trans-Activators; D004247:DNA