Concentric zones of active RhoA and Cdc42 around single cell wounds

Abstract

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 before F-actin accumulation, and then move in concert with the closing array. Microtubules and F-actin are required for normal zone organization and dynamics, as is crosstalk between RhoA and Cdc42. Each of the zones makes distinct contributions to the organization and function of the actomyosin wound array. We propose that similar rho activity zones control related processes such as cytokinesis.

Rho GTPase activity zones and transient contractile arrays

“…Analysis of Rho and Cdc42 activity during wound healing in Xenopus oocytes provided the prime example of Rho GTPase zones associated with a transient contractile array. (3) In this model system, PM damage elicits actin and myosin-2 assembly in a precisely bounded zone around wound borders. (16) The actomyosin array segregates over time: while F-actin assembles throughout the wound array, myosin-2 becomes enriched on the interior circumference.…”

“…Disruption of either the Rho or Cdc42 activity zone interferes with wound healing. (3) In addition, there is some evidence that Rac activity zones may also participate in this process (H. Benink and W. Bement, unpublished data).…”

“…(3) Conversely, Cdc42 activity during yeast budding has been studied intensely. Specifically, a Ras-related protein (Bud1p) and its corresponding GEF (Bud5p) and GAP (Bud2p) are recruited to the nascent bud site by proteins remaining from the previous round of cell division.…”

RhoA/ROCK-mediated switching between Cdc42- and Rac1-dependent protrusion in MTLn3 carcinoma cells

“…This model has been challenged by recent studies using fluorescence-based biosensors and other methods to visualize the subcellular distribution of Rho GTPase activity [14][15][16]. Recent reports have described a zone of RhoA/ROCK activation at the leading edge of cells [14,[17][18][19].…”

Affixin activates Rac1 via βPIX in C2C12 myoblast

“…In response to the sarcolemmal injury of muscle fibers, dysferlin patch was formed around wounded sites for resealing in a calcium-dependent manner. Calcium-dependent membrane resealing is also reported in wounded Xenopus oocyte, where Cdc42 and RhoA are activated [28]. Membrane repair is composed of two process: plasma membrane resealing and reorganization of subsarcolemmal cytoskeleton [29].…”