RT Journal Article SR Electronic T1 α-Endosulfine is a conserved protein required for oocyte meiotic maturation in Drosophila JF Development JO Development FD The Company of Biologists Limited SP 3697 OP 3706 DO 10.1242/dev.025114 VO 135 IS 22 A1 Von Stetina, Jessica R. A1 Tranguch, Susanne A1 Dey, Sudhansu K. A1 Lee, Laura A. A1 Cha, Byeong A1 Drummond-Barbosa, Daniela YR 2008 UL http://dev.biologists.org/content/135/22/3697.abstract AB Meiosis is coupled to gamete development and must be well regulated to prevent aneuploidy. During meiotic maturation, Drosophila oocytes progress from prophase I to metaphase I. The molecular factors controlling meiotic maturation timing, however, are poorly understood. We show that Drosophila α-endosulfine (endos) plays a key role in this process. endos mutant oocytes have a prolonged prophase I and fail to progress to metaphase I. This phenotype is similar to that of mutants of cdc2 (synonymous with cdk1) and of twine, the meiotic homolog of cdc25, which is required for Cdk1 activation. We found that Twine and Polo kinase levels are reduced in endos mutants, and identified Early girl (Elgi), a predicted E3 ubiquitin ligase, as a strong Endos-binding protein. In elgi mutant oocytes, the transition into metaphase I occurs prematurely, but Polo and Twine levels are unaffected. These results suggest that Endos controls meiotic maturation by regulating Twine and Polo levels, and, independently, by antagonizing Elgi. Finally, germline-specific expression of the humanα -endosulfine ENSA rescues the endos mutant meiotic defects and infertility, and α-endosulfine is expressed in mouse oocytes, suggesting potential conservation of its meiotic function.