title: The puromycin-sensitive aminopeptidase PAM-1 is required for meiotic exit and anteroposterior polarity in the one-cell Caenorhabditis elegans embryo.
abstract: In the nematode Caenorhabditis elegans, sperm entry into the oocyte triggers the completion of meiosis and the establishment of the embryonic anteroposterior (AP) axis. How the early embryo makes the transition from a meiotic to a mitotic zygote and coordinates cell cycle changes with axis formation remains unclear. We have discovered roles for the C. elegans puromycin-sensitive aminopeptidase PAM-1 in both cell cycle progression and AP axis formation, further implicating proteolytic regulation in these processes. pam-1 mutant embryos exhibit a delay in exit from meiosis: thus, this peptidase is required for progression to mitotic interphase. In addition, the centrosomes associated with the sperm pronucleus fail to closely associate with the posterior cortex in pam-1 mutants, and the AP axis is not specified. The meiotic exit and polarity defects are separable, as inactivation of the B-type cyclin CYB-3 in pam-1 mutants rescues the meiotic exit delay but not the polarity defects. Thus PAM-1 may regulate CYB-3 during meiotic exit but presumably targets other protein(s) to regulate polarity. We also show that the pam-1 gene is expressed both maternally and paternally, providing additional evidence that sperm-donated gene products have important roles during early embryogenesis in C. elegans. The degradation of proteins through ubiquitin-mediated proteolysis has been previously shown to regulate the cell cycle and AP axis formation in the C. elegans zygote. Our analysis of PAM-1 requirements shows that a puromycin-sensitive aminopeptidase is also required for proteolytic regulation of the oocyte to embryo transition.
authors.affiliation: Department of Biology, Ursinus College, Collegeville, PA 19426, USA. rlyczak@ursinus.edu
authors.forename: Rebecca
authors.initials: R
authors.lastname: Lyczak
authors.forename: Lynnsey
authors.initials: L
authors.lastname: Zweier
authors.forename: Thomas
authors.initials: T
authors.lastname: Group
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Murrow
authors.forename: Christine
authors.initials: C
authors.lastname: Snyder
authors.forename: Lindsay
authors.initials: L
authors.lastname: Kulovitz
authors.forename: Alexander
authors.initials: A
authors.lastname: Beatty
authors.forename: Kristen
authors.initials: K
authors.lastname: Smith
authors.forename: Bruce
authors.initials: B
authors.lastname: Bowerman
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology* / Q000201:enzymology* / Q000235:genetics; D016764:Cell Polarity; D018385:Centrosome / Q000378:metabolism; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D008540:Meiosis / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013094:Spermatozoa / Q000378:metabolism
chemical_list: D019926:Cyclin B; D011993:Recombinant Fusion Proteins; D000626:Aminopeptidases; C023191:PepT tripeptidase