title: P-TEFb, the super elongation complex and mediator regulate a subset of non-paused genes during early Drosophila embryo development.
abstract: Positive Transcription Elongation Factor b (P-TEFb) is a kinase consisting of Cdk9 and Cyclin T that releases RNA Polymerase II (Pol II) into active elongation. It can assemble into a larger Super Elongation Complex (SEC) consisting of additional elongation factors. Here, we use a miRNA-based approach to knock down the maternal contribution of P-TEFb and SEC components in early Drosophila embryos. P-TEFb or SEC depletion results in loss of cells from the embryo posterior and in cellularization defects. Interestingly, the expression of many patterning genes containing promoter-proximal paused Pol II is relatively normal in P-TEFb embryos. Instead, P-TEFb and SEC are required for expression of some non-paused, rapidly transcribed genes in pre-cellular embryos, including the cellularization gene Serendipity-α. We also demonstrate that another P-TEFb regulated gene, terminus, has an essential function in embryo development. Similar morphological and gene expression phenotypes were observed upon knock down of Mediator subunits, providing in vivo evidence that P-TEFb, the SEC and Mediator collaborate in transcription control. Surprisingly, P-TEFb depletion does not affect the ratio of Pol II at the promoter versus the 3' end, despite affecting global Pol II Ser2 phosphorylation levels. Instead, Pol II occupancy is reduced at P-TEFb down-regulated genes. We conclude that a subset of non-paused, pre-cellular genes are among the most susceptible to reduced P-TEFb, SEC and Mediator levels in Drosophila embryos.
authors: Dept. Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors: Olle
authors: O
authors: Dahlberg
authors: Dept. Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors: Olga
authors: O
authors: Shilkova
authors: Dept. Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Dept. Biochemistry & Biology, South China University, Hengyang, Hunan Province, China.
authors: Min
authors: M
authors: Tang
authors: Dept. Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors: Per-Henrik
authors: PH
authors: Holmqvist
authors: Dept. Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors: Mattias
authors: M
authors: Mannervik
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D056892:Mediator Complex / Q000235:genetics; D010641:Phenotype; D010766:Phosphorylation; D042925:Positive Transcriptional Elongation Factor B / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D056892:Mediator Complex; D042925:Positive Transcriptional Elongation Factor B; D012319:RNA Polymerase II