title: Combgap Promotes Ovarian Niche Development and Chromatin Association of EcR-Binding Regions in BR-C.
abstract: The development of niches for tissue-specific stem cells is an important aspect of stem cell biology. Determination of niche size and niche numbers during organogenesis involves precise control of gene expression. How this is achieved in the context of a complex chromatin landscape is largely unknown. Here we show that the nuclear protein Combgap (Cg) supports correct ovarian niche formation in Drosophila by controlling ecdysone-Receptor (EcR)- mediated transcription and long-range chromatin contacts in the broad locus (BR-C). Both cg and BR-C promote ovarian growth and the development of niches for germ line stem cells. BR-C levels were lower when Combgap was either reduced or over-expressed, indicating an intricate regulation of the BR-C locus by Combgap. Polytene chromosome stains showed that Cg co-localizes with EcR, the major regulator of BR-C, at the BR-C locus and that EcR binding to chromatin was sensitive to changes in Cg levels. Proximity ligation assay indicated that the two proteins could reside in the same complex. Finally, chromatin conformation analysis revealed that EcR-bound regions within BR-C, which span ~30 KBs, contacted each other. Significantly, these contacts were stabilized in an ecdysone- and Combgap-dependent manner. Together, these results highlight Combgap as a novel regulator of chromatin structure that promotes transcription of ecdysone target genes and ovarian niche formation.
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Anna
authors.identifier: http://orcid.org/0000-0002-3919-9585
authors.initials: A
authors.lastname: Hitrik
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Malka
authors.identifier: http://orcid.org/0000-0002-1327-0312
authors.initials: M
authors.lastname: Popliker
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Dana
authors.initials: D
authors.lastname: Gancz
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.|Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Zohar
authors.identifier: http://orcid.org/0000-0002-1623-9564
authors.initials: Z
authors.lastname: Mukamel
authors.affiliation: Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Aviezer
authors.initials: A
authors.lastname: Lifshitz
authors.affiliation: Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.|Mol. Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.|Childhood Leukemia Research Institute, Sheba Medical Center, Ramat Gan, Israel.
authors.forename: Omer
authors.identifier: http://orcid.org/0000-0002-4122-8111
authors.initials: O
authors.lastname: Schwartzman
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.|Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Amos
authors.initials: A
authors.lastname: Tanay
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Lilach
authors.identifier: http://orcid.org/0000-0002-9699-8594
authors.initials: L
authors.lastname: Gilboa
mesh_terms: D000818:Animals; D002843:Chromatin / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development; D004440:Ecdysone / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D009928:Organ Specificity; D010053:Ovary / Q000254:growth & development / Q000378:metabolism; D059007:Polytene Chromosomes / Q000235:genetics; D011987:Receptors, Steroid / Q000235:genetics*; D055153:Stem Cell Niche / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: C102117:Br protein, Drosophila; D002843:Chromatin; D029721:Drosophila Proteins; D011987:Receptors, Steroid; D014157:Transcription Factors; C416218:cg protein, Drosophila; C055469:ecdysone receptor; D004440:Ecdysone