Cofilin regulates actin network homeostasis and microvilli length in mouse oocytes

Anne Bourdais (1) , Benoit Dehapiot (1) , Guillaume Halet (1)

1 IGDR - Institut de Génétique et Développement de Rennes

How multiple actin networks coexist in a common cytoplasm while competing for a shared pool of monomers is still an ongoing question. This is exemplified by meiotic maturation in the mouse oocyte, which relies on the dynamic remodeling of distinct cortical and cytoplasmic F-actin networks. Here, we show that the conserved actin-depolymerizing factor cofilin is activated in a switch-like manner upon meiosis resumption from prophase arrest. Interfering with cofilin activation during maturation resulted in widespread elongation of microvilli, while cytoplasmic F-actin was depleted, leading to defects in spindle migration and polar body extrusion. In contrast, cofilin inactivation in metaphase II-arrested oocytes resulted in a shutdown of F-actin dynamics, along with a dramatic overgrowth of the polarized actin cap. However, inhibition of the Arp2/3 complex to promote actin cap disassembly elicited ectopic microvilli outgrowth in the polarized cortex. These data establish cofilin as a key player in actin network homeostasis in oocytes and reveal that microvilli can act as a sink for monomers upon disassembly of a competing network.

Mots clés: Actin; Cofilin; LIMK; Microvilli; Mouse; Oocyte

Domaines: Biologie du développement

Anne Bourdais, Benoit Dehapiot, Guillaume Halet. Cofilin regulates actin network homeostasis and microvilli length in mouse oocytes. Journal of Cell Science, 2021, 134 (24), pp.jcs259237. ⟨10.1242/jcs.259237⟩. ⟨hal-03519642⟩