title: G betagamma binds histone deacetylase 5 (HDAC5) and inhibits its transcriptional co-repression activity.
abstract: In a yeast two-hybrid screen designed to identify novel effectors of the G betagamma subunit of heterotrimeric G proteins, we found that G betagamma binds to histone deacetylase 5 (HDAC5), an enzyme involved in a pathway not previously recognized to be directly impacted by G proteins. Formation of the G beta1gamma2-HDAC5 complex in mammalian cells can be blocked by overexpression of G alpha(o), and this inhibition is relieved by activation of alpha2A-adrenergic receptor, suggesting that the interaction occurs in a signal-dependent manner. The C-terminal domain of HDAC5 binds directly to G betagamma through multiple motifs, and overexpression of this domain mimics the C terminus of G protein-coupled receptor kinase 2, a known G betagamma scavenger, in its ability to inhibit the G betagamma/HDAC5 interaction. The C terminus of HDAC4 shares significant similarity with that of HDAC5, and accordingly, HDAC4 is also able to form complexes with G beta1gamma2 in cultured cells, suggesting that the C-terminal domain of class II HDACs is a general G betagamma binding motif. Activation of a G(i/o)-coupled receptor results in a time-dependent activation of MEF2C, an HDAC5-regulated transcription factor, whereas inhibition of the interaction with a G betagamma scavenger inhibits MEF2C activity, suggesting a reduced potency of HDAC5-mediated inhibition. Taken together, these data imply that HDAC5 and possibly other class II HDACs can be added to the growing list of G betagamma effectors.
authors.affiliation: Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA.
authors.forename: Bryan D
authors.initials: BD
authors.lastname: Spiegelberg
authors.forename: Heidi E
authors.initials: HE
authors.lastname: Hamm
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002460:Cell Line; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000378:metabolism*; D017930:Genes, Reporter; D006655:Histone Deacetylases / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: C547768:ADRA2A protein, human; C547769:Adra2a protein, mouse; C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D018341:Receptors, Adrenergic, alpha-2; D012097:Repressor Proteins; C400300:HDAC4 protein, human; C404500:HDAC5 protein, human; D006655:Histone Deacetylases