title: Brahma regulates a specific trans-splicing event at the mod(mdg4) locus of Drosophila melanogaster.
abstract: The mod(mdg4) locus of Drosophila melanogaster contains several transcription units encoded on both DNA strands. The mod(mdg4) pre-mRNAs are alternatively spliced, and a very significant fraction of the mature mod(mdg4) mRNAs are formed by trans-splicing. We have studied the transcripts derived from one of the anti-sense regions within the mod(mdg4) locus in order to shed light on the expression of this complex locus. We have characterized the expression of anti-sense mod(mdg4) transcripts in S2 cells, mapped their transcription start sites and cleavage sites, identified and quantified alternatively spliced transcripts, and obtained insight into the regulation of the mod(mdg4) trans-splicing. In a previous study, we had shown that the alternative splicing of some mod(mdg4) transcripts was regulated by Brahma (BRM), the ATPase subunit of the SWI/SNF chromatin-remodeling complex. Here we show, using RNA interference and overexpression of recombinant BRM proteins, that the levels of BRM affect specifically the abundance of a trans-spliced mod(mdg4) mRNA isoform in both S2 cells and larvae. This specific effect on trans-splicing is accompanied by a local increase in the density of RNA polymerase II and by a change in the phosphorylation state of the C-terminal domain of the large subunit of RNA polymerase II. Interestingly, the regulation of the mod(mdg4) splicing by BRM is independent of the ATPase activity of BRM, which suggests that the mechanism by which BRM modulates trans-splicing is independent of its chromatin-remodeling activity.
authors: Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden.
authors: Simei
authors: S
authors: Yu
authors: Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden.
authors: Johan
authors: J
authors: Waldholm
authors: Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden.
authors: Stefanie
authors: S
authors: Böhm
authors: Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden.
authors: Neus
authors: N
authors: Visa
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D042002:Chromatin Assembly and Disassembly; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D012313:RNA / Q000378:metabolism*; D059367:RNA Cleavage; D034622:RNA Interference; D059368:RNA Isoforms / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D020040:Trans-Splicing; D014157:Transcription Factors / Q000235:genetics*; D024363:Transcription Initiation Site
chemical_list: D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D059368:RNA Isoforms; D015534:Trans-Activators; D014157:Transcription Factors; C086469:brm protein, Drosophila; C101384:mod(mdg4) protein, Drosophila; D012313:RNA; D012319:RNA Polymerase II
keywords: ATPase activity; RNA polymerase II; SWI/SNF; chromatin remodeling; splicing