Annexin A2 is required for the early steps of cytokinesis

Cytokinesis requires the formation of an actomyosin contractile ring between the two sets of sister chromatids. Annexin A2 is a calcium- and phospholipid-binding protein implicated in cortical actin remodeling. We report that annexin A2 accumulates at the equatorial cortex at the onset of cytokinesis and depletion of annexin A2 results in cytokinetic failure, due to a defective cleavage furrow assembly. In the absence of annexin A2, the small GTPase RhoA-which regulates cortical cytoskeletal rearrangement-fails to form a compact ring at the equatorial plane. Furthermore, annexin A2 is required for cortical localization of the RhoGEF Ect2 and to maintain the association between the equatorial cortex and the central spindle. Our results demonstrate that annexin A2 is necessary in the early phase of cytokinesis. We propose that annexin A2 participates in central spindle-equatorial plasma membrane communication.