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SPIN90 associates with mDia1 and the Arp2/3 complex to regulate cortical actin organization

Abstract : Cell shape is controlled by the submembranous cortex, an actomyosin network mainly generated by two actin nucleators: the Arp2/3 complex and the formin mDia1. Changes in relative nucleator activity may alter cortical organization, mechanics and cell shape. Here we investigate how nucleation-promoting factors mediate interactions between nucleators. In vitro, the nucleation-promoting factor SPIN90 promotes formation of unbranched filaments by Arp2/3, a process thought to provide the initial filament for generation of dendritic networks. Paradoxically, in cells, SPIN90 appears to favour a formin-dominated cortex. Our in vitro experiments reveal that this feature stems mainly from two mechanisms: efficient recruitment of mDia1 to SPIN90–Arp2/3 nucleated filaments and formation of a ternary SPIN90–Arp2/3–mDia1 complex that greatly enhances filament nucleation. Both mechanisms yield rapidly elongating filaments with mDia1 at their barbed ends and SPIN90–Arp2/3 at their pointed ends. Thus, in networks, SPIN90 lowers branching densities and increases the proportion of long filaments elongated by mDia1.
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Contributor : Aurélie Bertin <>
Submitted on : Tuesday, January 19, 2021 - 4:35:05 PM
Last modification on : Thursday, January 21, 2021 - 3:29:32 AM


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Luyan Cao, Amina Yonis, Malti Vaghela, Elias Barriga, Priyamvada Chugh, et al.. SPIN90 associates with mDia1 and the Arp2/3 complex to regulate cortical actin organization. Nature Cell Biology, Nature Publishing Group, 2020, 22, pp.803 - 814. ⟨10.1038/s41556-020-0531-y⟩. ⟨hal-03006846⟩



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