Vasa promotes Drosophila germline stem cell differentiation by activating mei-P26 translation by directly interacting with a (U)-rich motif in its 3' UTR.
Vasa (Vas) is a DEAD-box RNA-binding protein required in Drosophila at several steps of oogenesis and for primordial germ cell (PGC) specification. Vas associates with eukaryotic initiation factor 5B (eIF5B), and this interaction has been implicated in translational activation of gurken mRNA in the oocyte. Vas is expressed in all ovarian germline cells, and aspects of the vas-null phenotype suggest a function in regulating the balance between germline stem cells (GSCs) and their fate-restricted descendants. We used a biochemical approach to recover Vas-associated mRNAs and obtained mei-P26, whose product represses microRNA activity and promotes GSC differentiation. We found that vas and mei-P26 mutants interact, and that mei-P26 translation is substantially reduced in vas mutant cells. In vitro, Vas protein bound specifically to a (U)-rich motif in the mei-P26 3' untranslated region (UTR), and Vas-dependent regulation of GFP-mei-P26 transgenes in vivo was dependent on the same (U)-rich 3' UTR domain. The ability of Vas to activate mei-P26 expression in vivo was abrogated by a mutation that greatly reduces its interaction with eIF5B. Taken together, our data support the conclusion that Vas promotes germ cell differentiation by directly activating mei-P26 translation in early-stage committed cells.
Liu
Niankun
N
Department of Biology, Developmental Biology Research Initiative, and Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1B1, Canada.
Han
Hong
H
Lasko
Paul
P
D020413:3' Untranslated Regions; D020816:Amino Acid Motifs; D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D005854:Germ Cells / Q000166:cytology*; D012333:RNA, Messenger / Q000302:isolation & purification; D013234:Stem Cells / Q000166:cytology*; D019076:Transgenes; D014498:Uracil / Q000378:metabolism
D020413:3' Untranslated Regions; D029721:Drosophila Proteins; C530643:Mei-P26 protein, Drosophila; D012333:RNA, Messenger; D014498:Uracil; C088269:vas protein, Drosophila; D053487:DEAD-box RNA Helicases