Regulation of MBK-2/Dyrk kinase by dynamic cortical anchoring during the oocyte-to-zygote transition.
BACKGROUND
Successful transition from oocyte to zygote depends on the timely degradation of oocyte proteins to prepare for embryonic development. In C. elegans, degradation of the oocyte protein MEI-1 depends on MBK-2, a kinase that phosphorylates MEI-1 shortly after fertilization during the second meiotic division.


RESULTS
Here we report that precise timing of MEI-1 phosphorylation depends on the cell cycle-regulated release of MBK-2 from the cortex. Prior to the meiotic divisions, MBK-2 is tethered at the cortex by EGG-3, an oocyte protein required for egg activation (see [1], accompanying paper in this issue). During the meiotic divisions, EGG-3 is internalized and degraded in an APC/C (anaphase-promoting complex/cyclosome)-dependent manner. EGG-3 internalization and degradation correlate with MBK-2 release from the cortex and MEI-1 phosphorylation in the cytoplasm. In an egg-3 mutant, MEI-1 is phosphorylated and degraded prematurely.


CONCLUSIONS
We suggest that successful transition from an oocyte to a zygote depends on the cell cycle-regulated relocalization of key regulators from the cortex to the cytoplasm of the egg.
Stitzel
Michael L
ML
Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 North Wolfe Street, PCTB 706, Baltimore, Maryland 21205, USA.
Cheng
Ken Chih-Chien
KC
Seydoux
Geraldine
G
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000032:analysis; D008540:Meiosis; D008969:Molecular Sequence Data; D009865:Oocytes / Q000201:enzymology* / Q000254:growth & development; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000032:analysis; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D015053:Zygote / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D044767:Ubiquitin-Protein Ligases; C478059:MBK-2 protein, C elegans; D011505:Protein-Tyrosine Kinases; C525138:EGG-3 protein, C elegans; D017027:Protein Tyrosine Phosphatases; D000251:Adenosine Triphosphatases; C086678:MEI-1 protein, C elegans