title: PARP-1 determines specificity in a retinoid signaling pathway via direct modulation of mediator.
abstract: We show that PARP-1 is indispensable to retinoic acid receptor (RAR)-mediated transcription from the RARbeta2 promoter in a highly purified, reconstituted transcription system and that RA-inducible expression of all RARbeta isoforms is abrogated in PARP-1(-/-) cells in vivo. Importantly, PARP-1 activity was independent of its catalytic domain. PARP-1 directly interacts with RAR and Mediator. Chromatin immunoprecipitation experiments confirmed the presence of PARP-1 and Mediator on RAR-responsive promoters in vivo. Importantly, Mediator was inactive (Cdk8+) under basal conditions but was activated (Cdk8-) upon induction. However, in PARP-1(-/-) cells, Mediator was retained in its inactive state (Cdk8+) upon induction consistent with the absence of gene expression. PARP-1 became dispensable for ligand-dependent transcription in a chromatin reconstituted transcription assay when Mediator was devoid of the Cdk8 module (CRSP). PARP-1 appears to function as a specificity factor regulating the RA-induced switch of Mediator from the inactive (Cdk8+) to the active (Cdk8-) state in RAR-dependent transcription.
authors.affiliation: Department of Biochemistry, Howard Hughes Medical Institute, University of Medicine and Dentistry of New Jersey, 683 Hoes Lane, Piscataway, New Jersey 08854, USA.
authors.forename: Rushad
authors.initials: R
authors.lastname: Pavri
authors.forename: Brian
authors.initials: B
authors.lastname: Lewis
authors.forename: Tae-Kyung
authors.initials: TK
authors.lastname: Kim
authors.forename: F Jeffrey
authors.initials: FJ
authors.lastname: Dilworth
authors.forename: Hediye
authors.initials: H
authors.lastname: Erdjument-Bromage
authors.forename: Paul
authors.initials: P
authors.lastname: Tempst
authors.forename: Gilbert
authors.initials: G
authors.lastname: de Murcia
authors.forename: Ronald
authors.initials: R
authors.lastname: Evans
authors.forename: Pierre
authors.initials: P
authors.lastname: Chambon
authors.forename: Danny
authors.initials: D
authors.lastname: Reinberg
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000502:physiology; D019281:Dimerization; D017353:Gene Deletion; D006367:HeLa Cells; D006801:Humans; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection
chemical_list: D018168:Receptors, Retinoic Acid; D011994:Recombinant Proteins; C082925:retinoic acid receptor beta; D011065:Poly(ADP-ribose) Polymerases