title: A genome-wide RNA interference screen identifies a differential role of the mediator CDK8 module subunits for GATA/ RUNX-activated transcription in Drosophila.
abstract: Transcription factors of the RUNX and GATA families play key roles in the control of cell fate choice and differentiation, notably in the hematopoietic system. During Drosophila hematopoiesis, the RUNX factor Lozenge and the GATA factor Serpent cooperate to induce crystal cell differentiation. We used Serpent/Lozenge-activated transcription as a paradigm to identify modulators of GATA/RUNX activity by a genome-wide RNA interference screen in cultured Drosophila blood cells. Among the 129 factors identified, several belong to the Mediator complex. Mediator is organized in three modules plus a regulatory "CDK8 module," composed of Med12, Med13, CycC, and Cdk8, which has long been thought to behave as a single functional entity. Interestingly, our data demonstrate that Med12 and Med13 but not CycC or Cdk8 are essential for Serpent/Lozenge-induced transactivation in cell culture. Furthermore, our in vivo analysis of crystal cell development show that, while the four CDK8 module subunits control the emergence and the proliferation of this lineage, only Med12 and Med13 regulate its differentiation. We thus propose that Med12/Med13 acts as a coactivator for Serpent/Lozenge during crystal cell differentiation independently of CycC/Cdk8. More generally, we suggest that the set of conserved factors identified herein may regulate GATA/RUNX activity in mammals.
authors.affiliation: Université de Toulouse; UPS, CBD (Centre de Biologie du Développement), Bâtiment 4R3, 118 route de Narbonne, 31062 Toulouse, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Gobert
authors.forename: Dani
authors.initials: D
authors.lastname: Osman
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Bras
authors.forename: Benoit
authors.initials: B
authors.lastname: Augé
authors.forename: Muriel
authors.initials: M
authors.lastname: Boube
authors.forename: Henri-Marc
authors.initials: HM
authors.lastname: Bourbon
authors.forename: Thomas
authors.initials: T
authors.lastname: Horn
authors.forename: Michael
authors.initials: M
authors.lastname: Boutros
authors.forename: Marc
authors.initials: M
authors.lastname: Haenlin
authors.forename: Lucas
authors.initials: L
authors.lastname: Waltzer
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D056850:Cyclin-Dependent Kinase 8 / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D016678:Genome; D006410:Hematopoiesis / Q000502:physiology; D057166:High-Throughput Screening Assays / Q000379:methods; D056892:Mediator Complex / Q000235:genetics / Q000378:metabolism*; D025941:Protein Interaction Mapping; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D050980:GATA Transcription Factors; D056892:Mediator Complex; D021122:Protein Subunits; D014157:Transcription Factors; C099964:lz protein, Drosophila; C103965:srp protein, Drosophila; D056850:Cyclin-Dependent Kinase 8