Myosin X Is Involved In Neuronal Polarization

Myosin X (Myosin X, Myo X) is a non-conventional myosin which can be expressedin the vertebrate. Its tail region can specific bind to microtubule, and the microtubule is themajor constitute of the cytoskeletal in neurons. Stable microtubules in the shaft of axon isessential for the initial small neurite gathering forward to form an axon, suggesting thatMyosin Xmay regulate microtubule stabilization to affact neuronal polarity.Basic results in our laboratory used the primary hippocampal neuron culture system,neurons were transfected with the scramble siRNA and Myo XsiRNA plasmids respectively,after three days, Tau-1immunofluorescence staining was represented negative, theexperiment suggested that Myo Xwas involved in axon formation. To further analyze therole of microtubules in Myo Xparticipated axon development, we examined the twoindicators of microtubule: stabilty microtubules (Acetylated-tublin) and dynamicmicrotubules (Tyrosinated-tublin). We proved that Myo Xaffected the neuronal polarizationby changing distribution of the two indicators in the neurites. Further proof showed theinhibitor of GSK3βcalled SB415286also can remedy Myo X siRNA defect, leading Tau-1negative and inducing multiple axons. The result demonstrated Myo Xcan participate thePIP3-Akt-GSK3β signaling pathway and play a role in the upstream of GSK3β. Finally, thewestern blotting assay confirmed that, in the Myo XsiRNA group, there was no significantchanges of GSK3β distribution in the various protrusions, but aggregation state ofpGSK3βexpression on the tip of axon was different.There are two forms of Myo X may involved in the different stages of neuraldevelopment: Myosin X Headless and Myosin XFulllength. We designed and constructedthe two forms of Myosin X respectively by silencing the5ˊUTR region and detected theefficiency of their silence by the luciferase reporting system.