title: Polo-mediated phosphorylation of Maelstrom regulates oocyte determination during oogenesis in Drosophila.
abstract: In Drosophila, Maelstrom is a conserved component of the perinuclear nuage, a germline-unique structure that appears to serve as a site for Piwi-interacting RNA (piRNA) production to repress deleterious transposons. Maelstrom also functions in the nucleus as a transcriptional regulator to repress the expression of microRNA-7, a process that is essential for the proper differentiation of germline stem cells. In this paper, we report another function of Maelstrom in regulating oocyte determination independently of its transposon silencing and germline stem cell differentiation activities. In Drosophila, the conserved serine 138 residue in Maelstrom is required for its phosphorylation, an event that promotes oocyte determination. Phosphorylation of Maelstrom is required for the repression of the pachytene checkpoint protein Sir2, but not for transposon silencing or for germline stem cell differentiation. We identify Polo as a kinase that mediates the phosphorylation of Maelstrom. Our results suggest that the Polo-mediated phosphorylation of Maelstrom may be a mechanism that controls oocyte determination by inactivating the pachytene checkpoint via the repression of Sir2 in Drosophila ovaries.
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link National University of Singapore, Singapore 117604.
authors.forename: Jun Wei
authors.initials: JW
authors.lastname: Pek
authors.forename: Bing Fu
authors.initials: BF
authors.lastname: Ng
authors.forename: Toshie
authors.initials: T
authors.lastname: Kai
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics; D004330:Drosophila / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D005260:Female; D020868:Gene Silencing; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D009865:Oocytes / Q000378:metabolism* / Q000502:physiology; D009866:Oogenesis / Q000235:genetics / Q000502:physiology; D010053:Ovary / Q000378:metabolism; D049471:Pachytene Stage / Q000235:genetics; D010766:Phosphorylation / Q000235:genetics / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D037761:Sirtuins / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D004251:DNA Transposable Elements; D029721:Drosophila Proteins; C109767:mael protein, Drosophila; C072004:polo protein, Drosophila; D017346:Protein Serine-Threonine Kinases; C447899:Sirt2 protein, Drosophila; D037761:Sirtuins; D006655:Histone Deacetylases