PAR-2 is asymmetrically distributed and promotes association of P granules and PAR-1 with the cortex in C. elegans embryos.
The par genes participate in the process of establishing cellular asymmetries during the first cell cycle of Caenorhabditis elegans development. The par-2 gene is required for the unequal first cleavage and for asymmetries in cell cycle length and spindle orientation in the two resulting daughter cells. We have found that the PAR-2 protein is present in adult gonads and early embryos. In gonads, the protein is uniformly distributed at the cell cortex, and this subcellular localization depends on microfilaments. In the one-cell embryo, PAR-2 is localized to the posterior cortex and is partitioned into the posterior daughter, P1, at the first cleavage. PAR-2 exhibits a similar asymmetric cortical localization in P1, P2, and P3, the asymmetrically dividing blastomeres of germ line lineage. This distribution in embryos is very similar to that of PAR-1 protein. By analyzing the distribution of the PAR-2 protein in various par mutant backgrounds we found that proper asymmetric distribution of PAR-2 depends upon par-3 activity but not upon par-1 or par-4. par-2 activity is required for proper cortical localization of PAR-1 and this effect requires wild-type par-3 gene activity. We also find that, although par-2 activity is not required for posterior localization of P granules at the one-cell stage, it is required for proper cortical association of P granules in P1.
Boyd
L
L
Section of Genetics and Development, Cornell University, Ithaca, NY 14853, USA.
Guo
S
S
Levitan
D
D
Stinchcomb
D T
DT
Kemphues
K J
KJ
D000818:Animals; D001757:Blastomeres / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017346:Protein Serine-Threonine Kinases; D029701:Saccharomyces cerevisiae Proteins
D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D015801:Helminth Proteins; D029701:Saccharomyces cerevisiae Proteins; C087977:par-2 protein, C elegans; C097238:PAR-3 protein, C elegans; D017346:Protein Serine-Threonine Kinases