title: Functional specialization of chordate CDK1 paralogs during oogenic meiosis.
abstract: Cyclin-dependent kinases (CDKs) are central regulators of eukaryotic cell cycle progression. In contrast to interphase CDKs, the mitotic phase CDK1 is the only CDK capable of driving the entire cell cycle and it can do so from yeast to mammals. Interestingly, plants and the marine chordate, Oikopleura dioica, possess paralogs of the highly conserved CDK1 regulator. However, whereas in plants the 2 CDK1 paralogs replace interphase CDK functions, O. dioica has a full complement of interphase CDKs in addition to its 5 odCDK1 paralogs. Here we show specific sub-functionalization of odCDK1 paralogs during oogenesis. Differential spatiotemporal dynamics of the odCDK1a, d and e paralogs and the meiotic polo-like kinase 1 (Plk1) and aurora kinase determine the subset of meiotic nuclei in prophase I arrest that will seed growing oocytes and complete meiosis. Whereas we find odCDK1e to be non-essential, knockdown of the odCDK1a paralog resulted in the spawning of non-viable oocytes of reduced size. Knockdown of odCDK1d also resulted in the spawning of non-viable oocytes. In this case, the oocytes were of normal size, but were unable to extrude polar bodies upon exposure to sperm, because they were unable to resume meiosis from prophase I arrest, a classical function of the sole CDK1 during meiosis in other organisms. Thus, we reveal specific sub-functionalization of CDK1 paralogs, during the meiotic oogenic program.
authors.affiliation: a Department of Biology ; University of Bergen ; Bergen , Norway.
authors.forename: Jan Inge
authors.initials: JI
authors.lastname: Øvrebø
authors.forename: Coen
authors.initials: C
authors.lastname: Campsteijn
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kourtesis
authors.forename: Harald
authors.initials: H
authors.lastname: Hausen
authors.forename: Martina
authors.initials: M
authors.lastname: Raasholm
authors.forename: Eric M
authors.initials: EM
authors.lastname: Thompson
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D043344:Chordata / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D008540:Meiosis; D022101:Microtubule-Organizing Center / Q000378:metabolism / Q000648:ultrastructure; D009685:Nuclear Envelope / Q000378:metabolism; D009866:Oogenesis; D010641:Phenotype; D012330:RNA, Double-Stranded / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D012330:RNA, Double-Stranded; D016203:CDC2 Protein Kinase
keywords: CDK, Cyclin Dependent Kinase; DMYPT, Drosophila myosin phosphatase; GVBD, germinal vesicle breakdown; MAPK, Mitogen-Activated Protein Kinase; MTOC; MTOC, microtubule organizing center; NEBD, nuclear envelope breakdown; NPC, Nuclear Pore Complex; OC, Organizing Center; Plk1, Polo-like kinase 1; aurora kinase; centrosome; cmRNA, capped messenger RNA; dsRNA, double-stranded RNA; endocycle; polo-like kinase; syncytium; urochordate