Drosophila anterior-posterior polarity requires actin-dependent PAR-1 recruitment to the oocyte posterior.
The Drosophila anterior-posterior axis is established at stage 7 of oogenesis when the posterior follicle cells signal to polarize the oocyte microtubule cytoskeleton. This requires the conserved PAR-1 kinase, which can be detected at the posterior of the oocyte in immunostainings from stage 9. However, this localization depends on Oskar localization, which requires the earlier PAR-1-dependent microtubule reorganization, indicating that Oskar-associated PAR-1 cannot establish oocyte polarity. Here we analyze the function of the different PAR-1 isoforms and find that only PAR-1 N1 isoforms can completely rescue the oocyte polarity phenotype. Furthermore, PAR-1 N1 is recruited to the posterior cortex of the oocyte at stage 7 in response to the polarizing follicle cell signal, and this requires actin, but not microtubules. This suggests that posterior PAR-1 N1 polarizes the microtubule cytoskeleton. PAR-1 N1 localization is mediated by a cortical targeting domain and a conserved anterior-lateral exclusion signal in its C-terminal linker domain. PAR-1 is also required for the polarization of the C. elegans zygote and is recruited to the posterior cortex in an actin-dependent manner. Our results therefore identify a molecular parallel between axis formation in Drosophila and C. elegans and make Drosophila PAR-1 N1 the earliest known marker for the polarization of the oocyte.
Doerflinger
Hélène
H
The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, United Kingdom.
Benton
Richard
R
Torres
Isabel L
IL
Zwart
Maarten F
MF
St Johnston
Daniel
D
D000199:Actins / Q000378:metabolism / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000254:growth & development / Q000378:metabolism; D017124:Conserved Sequence; D004330:Drosophila / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029721:Drosophila Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D038362:Glycogen Synthase Kinase 3; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development; D020033:Protein Isoforms / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D011494:Protein Kinases / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000032:analysis
D000199:Actins; D029721:Drosophila Proteins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D038362:Glycogen Synthase Kinase 3; C472496:Par-1 protein, Drosophila