Par-1 and Tau regulate the anterior-posterior gradient of microtubules in Drosophila oocytes.
The formation of an anterior-posterior (AP) gradient of microtubules in Drosophila oocytes is essential for specification of the AP axis. Proper microtubule organization in the oocyte requires the function of serine/threonine kinase Par-1. The N1S isoform of Par-1 is enriched at the posterior cortex of the oocyte from stage 7 of oogenesis. Here we report that posterior restriction of Par-1 (N1S) kinase activity is critical for microtubule AP gradient formation. Egg chambers with excessive and ectopic Par-1 (N1S) kinase activity in the germline cells display phenotypes similar to those of egg chambers treated with the microtubule-depolymerizing drug colcemid: depolymerization of microtubules in the oocyte and disruption of oocyte nucleus localization. A phosphorylation target of Par-1, the microtubule-associated protein Tau, is also involved in oocyte polarity formation, and overexpression of Tau alleviates the phenotypes caused by ectopic Par-1 (N1S) kinase activity, suggesting that Par-1 regulates oocyte polarity at least partly through Tau. Our findings reveal that maintaining proper levels of Par-1 at correct position in the oocyte is key to oocyte polarity formation and that the conserved role of Par-1 and Tau is crucial for the establishment of an AP gradient of microtubules and for AP axis specification.
Tian
Ai-Guo
AG
Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA.
Deng
Wu-Min
WM
D000818:Animals; D016764:Cell Polarity; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3; D008870:Microtubules / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism; D009866:Oogenesis / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016875:tau Proteins / Q000235:genetics / Q000378:metabolism*
D029721:Drosophila Proteins; D011993:Recombinant Fusion Proteins; D016875:tau Proteins; D017346:Protein Serine-Threonine Kinases; D038362:Glycogen Synthase Kinase 3; C472496:Par-1 protein, Drosophila