title: An RNAi screen identifies additional members of the Drosophila Integrator complex and a requirement for cyclin C/Cdk8 in snRNA 3'-end formation.
abstract: Formation of the 3' end of RNA polymerase II-transcribed snRNAs requires a poorly understood group of proteins called the Integrator complex. Here we used a fluorescence-based read-through reporter that expresses GFP in response to snRNA misprocessing and performed a genome-wide RNAi screen in Drosophila S2 cells to identify novel factors required for snRNA 3'-end formation. In addition to the known Integrator complex members, we identified Asunder and CG4785 as additional Integrator subunits. Functional and biochemical experiments revealed that Asunder and CG4785 are additional core members of the Integrator complex. We also identified a conserved requirement in both fly and human snRNA 3'-end processing for cyclin C and Cdk8 that is distinct from their function in the Mediator Cdk8 module. Moreover, we observed biochemical association between Integrator proteins and cyclin C/Cdk8, and that overexpression of a kinase-dead Cdk8 causes snRNA misprocessing. These data functionally define the Drosophila Integrator complex and demonstrate an additional function for cyclin C/Cdk8 unrelated to its function in Mediator.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, Texas 77030, USA.
authors.forename: Jiandong
authors.initials: J
authors.lastname: Chen
authors.forename: Nader
authors.initials: N
authors.lastname: Ezzeddine
authors.forename: Bernhard
authors.initials: B
authors.lastname: Waltenspiel
authors.forename: Todd R
authors.initials: TR
authors.lastname: Albrecht
authors.forename: William D
authors.initials: WD
authors.lastname: Warren
authors.forename: William F
authors.initials: WF
authors.lastname: Marzluff
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Wagner
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000235:genetics* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D056745:Cyclin C / Q000378:metabolism*; D056850:Cyclin-Dependent Kinase 8 / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D006801:Humans; D056892:Mediator Complex / Q000235:genetics / Q000378:metabolism; D026721:RNA 3' End Processing; D034622:RNA Interference; D012342:RNA, Small Nuclear / Q000235:genetics* / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D001798:Blood Proteins; D018797:Cell Cycle Proteins; C503678:CycC protein, Drosophila; D056745:Cyclin C; D029721:Drosophila Proteins; D056892:Mediator Complex; D012342:RNA, Small Nuclear; C544294:asun protein, Drosophila; C518075:psidin protein, Drosophila; C498308:Cdk8 protein, Drosophila; D056850:Cyclin-Dependent Kinase 8