title: tBRD-1 selectively controls gene activity in the Drosophila testis and interacts with two new members of the bromodomain and extra-terminal (BET) family.
abstract: Multicellular organisms have evolved specialized mechanisms to control transcription in a spatial and temporal manner. Gene activation is tightly linked to histone acetylation on lysine residues that can be recognized by bromodomains. Previously, the testis-specifically expressed bromodomain protein tBRD-1 was identified in Drosophila. Expression of tBRD-1 is restricted to highly transcriptionally active primary spermatocytes. tBRD-1 is essential for male fertility and proposed to act as a co-factor of testis-specific TATA box binding protein-associated factors (tTAFs) for testis-specific transcription. Here, we performed microarray analyses to compare the transcriptomes of tbrd-1 mutant testes and wild-type testes. Our data confirmed that tBRD-1 controls gene activity in male germ cells. Additionally, comparing the transcriptomes of tbrd-1 and tTAF mutant testes revealed a subset of common target genes. We also characterized two new members of the bromodomain and extra-terminal (BET) family, tBRD-2 and tBRD-3. In contrast to other members of the BET family in animals, both possess only a single bromodomain, a characteristic feature of plant BET family members. Immunohistology techniques not only revealed that tBRD-2 and tBRD-3 partially co-localize with tBRD-1 and tTAFs in primary spermatocytes, but also that their proper subcellular distribution was impaired in tbrd-1 and tTAF mutant testes. Treating cultured male germ cells with inhibitors showed that localization of tBRD-2 and tBRD-3 depends on the acetylation status within primary spermatocytes. Yeast two-hybrid assays and co-immunoprecipitations using fly testes protein extracts demonstrated that tBRD-1 is able to form homodimers as well as heterodimers with tBRD-2, tBRD-3, and tTAFs. These data reveal for the first time the existence of single bromodomain BET proteins in animals, as well as evidence for a complex containing tBRDs and tTAFs that regulates transcription of a subset of genes with relevance for spermiogenesis.
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Theofel
authors.affiliation: Institute for Genetics, Justus-Liebig-University, Giessen, Germany.
authors.forename: Marek
authors.initials: M
authors.lastname: Bartkuhn
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Hundertmark
authors.affiliation: Department of Cardiac Development and Remodeling, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Boettger
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Stefanie M K
authors.initials: SM
authors.lastname: Gärtner
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Leser
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Awe
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schipper
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Renkawitz-Pohl
authors.affiliation: Philipps-University Marburg, Department of Biology, Marburg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Rathke
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D029721:Drosophila Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology; D005786:Gene Expression Regulation; D008297:Male; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D060066:Protein Interaction Maps; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism; D013091:Spermatogenesis; D035381:TATA-Binding Protein Associated Factors; D013737:Testis / Q000166:cytology / Q000378:metabolism*; D000092468:Bromodomain Containing Proteins
chemical_list: D029721:Drosophila Proteins; D009687:Nuclear Proteins; D035381:TATA-Binding Protein Associated Factors; C000598684:tBRD-1 protein, Drosophila; D000092468:Bromodomain Containing Proteins