title: Bam and Bgcn antagonize Nanos-dependent germ-line stem cell maintenance.
abstract: The balance between germ-line stem cell (GSC) self-renewal and differentiation in Drosophila ovaries is mediated by the antagonistic relationship between the Nanos (Nos)-Pumilio translational repressor complex, which promotes GSC self-renewal, and expression of Bam, a key differentiation factor. Here, we find that Bam and Nos proteins are expressed in reciprocal patterns in young germ cells. Repression of Nos in Bam-expressing cells depends on sequences in the nos 3'-UTR, suggesting that Nos is regulated by translational repression. Ectopic Bam causes differentiation of GSCs, and this activity depends on the endogenous nos 3'-UTR sequence. Previous evidence showed that Bgcn is an obligate factor for the ability of Bam to drive differentiation, and we now report that Bam forms a complex with Bgcn, a protein related to the RNA-interacting DExH-box polypeptides. Together, these observations suggest that Bam-Bgcn act together to antagonize Nos expression; thus, derepressing cystoblast-promoting factors. These findings emphasize the importance of translational repression in balancing stem cell self-renewal and differentiation.
authors.affiliation: Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.forename: Nicole T
authors.initials: NT
authors.lastname: Minor
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Park
authors.forename: Dennis M
authors.initials: DM
authors.lastname: McKearin
authors.forename: Jean Z
authors.initials: JZ
authors.lastname: Maines
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D002454:Cell Differentiation; D004265:DNA Helicases / Q000378:metabolism*; D004330:Drosophila / Q000166:cytology* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005854:Germ Cells / Q000166:cytology*; D010053:Ovary / Q000166:cytology / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology*
chemical_list: D020413:3' Untranslated Regions; D029721:Drosophila Proteins; D016601:RNA-Binding Proteins; C091674:bam protein, Drosophila; C070574:nos protein, Drosophila; D004265:DNA Helicases; C414082:bgcn protein, Drosophila