Characterization of Rho GTPases during wound healing

Rho GTPases control many cytoskeleton-dependent processes, but how they regulate spatially distinct features of cytoskeletal function within a single cell is poorly understood. Here we studied active RhoA and Cdc42 in wounded Xenopus oocytes, which assemble and close a dynamic ring of actin filaments (F-actin) and myosin-2 around wound sites. RhoA and Cdc42 are rapidly activated around wound sites in a calcium-dependent manner and segregate into distinct, concentric zones around the wound, with active Cdc42 in the approximate middle of the F-actin array, and active RhoA on the interior of the array. These zones form prior to F-actin accumulation, move in concert with the closing array and dictate the localization of downstream targets responsible for wound closure. Microtubules and F-actin are required for normal zone organization and dynamics, as is crosstalk between RhoA, Cdc42 and Rac. Each of the zones makes distinct contributions to the organization and function of the actomyosin wound array, consistent with their known roles. We propose that similar Rho activity zones control processes ranging from cell locomotion to cytokinesis.