title: Cyclin E/Cdk2 is required for sperm maturation, but not DNA replication, in early sea urchin embryos.
abstract: The cell cycle is driven by the activity of cyclin/cdk complexes. In somatic cells, cyclin E/cdk2 oscillates throughout the cell cycle and has been shown to promote S-phase entry and initiation of DNA replication. In contrast, cyclin E/cdk2 activity remains constant throughout the early embryonic development of the sea urchin and localizes to the sperm nucleus following fertilization. We now show that cyclin E localization to the sperm nucleus following fertilization is not unique to the sea urchin, but also occurs in the surf clam, and inhibition of cyclin E/cdk2 activity by roscovitine inhibits the morphological changes indicative of male pronuclear maturation in sea urchin zygotes. Finally, we show that inhibition of cyclin E/cdk2 activity does not block DNA replication in the early cleavage cycles of the sea urchin. We conclude that cyclin E/cdk2 activity is required for male pronuclear maturation, but not for initiation of DNA replication in early sea urchin development.
authors: Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. SchnackenbergBradley@uams.edu
authors: Bradley J
authors: BJ
authors: Schnackenberg
authors: Robert E
authors: RE
authors: Palazzo
authors: William F
authors: WF
authors: Marzluff
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D019927:Cyclin E / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004261:DNA Replication; D005260:Female; D008297:Male; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D000077546:Roscovitine; D013045:Species Specificity; D013077:Sperm Head / Q000378:metabolism; D013079:Sperm Maturation / Q000502:physiology*; D049890:Spisula / Q000196:embryology / Q000378:metabolism; D047270:Strongylocentrotus purpuratus / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism*; D015053:Zygote / Q000378:metabolism
chemical_list: D019927:Cyclin E; D047428:Protein Kinase Inhibitors; D011687:Purines; D000077546:Roscovitine; D051357:Cyclin-Dependent Kinase 2