The <i>Drosophila</i> Anterior-Posterior Axis is Polarized by Asymmetric Myosin Activation

The Drosophila anterior-posterior (AP) axis is specified at mid-oogenesis when Par-1 kinase recruited to the posterior cortex of oocyte, where it polarises microtubule cytoskeleton define determinants, bicoid and oskar mRNAs localise. This polarity established in response an unknown signal from follicle cells, but how this occurs unclear. Here we show that myosin chaperone, Unc-45 Non-Muscle Myosin II (MyoII) are required germ line upstream establishment. Furthermore, regulatory Light Chain (MRLC) di-phosphorylated oocyte cell signal, inducing longer pulses contractility increased cortical tension.  Over-expression MRLC-T21A cannot be or acute treatment with light chain inhibitor ML-7 abolish localisation, indicating MRLC di-phosphorylation essential for  polarity. Thus, asymmetric activation polarizes by recruiting maintaining cortex.  raises intriguing parallel AP formation C. elegans MyoII also establish polarity, functions localize anterior PAR proteins rather than PAR-1.