A gelation transition enables the self-organization of bipolar metaphase spindles

Abstract The mitotic spindle is a highly dynamic bipolar structure that emerges from the self-organization of microtubules, molecular motors and other proteins. Sustained motor-driven poleward flows microtubules play key role in organization spindles. However, it not understood how local activity motor proteins generates these large-scale coherent flows. Here we show gelation transition enables long-range microtubule transport causing spindles to self-organize into two oppositely polarized gels. Laser ablation experiments reveal active stresses generated at midplane propagate through structure, thereby driving global Simulations gels undergoing rapid turnover can exhibit long stress relaxation times, agreement with observed experiments. Finally, our model predicts presence branching nucleation, either disrupting such or decreasing network connectivity lead polarity reversal We experimentally confirm this inversion by abolishing Overall, uncover connection between rheology architecture self-organization.