RhoA is required for monocyte tail retraction during transendothelial migration

Abstract

Transendothelial migration of monocytes is the process by which monocytes leave the circulatory system and extravasate through the endothelial lining of the blood vessel wall and enter the underlying tissue. Transmigration requires coordination of alterations in cell shape and adhesive properties that are mediated by cytoskeletal dynamics. We have analyzed the function of RhoA in the cytoskeletal reorganizations that occur during transmigration. By loading monocytes with C3, an inhibitor of RhoA, we found that RhoA was required for transendothelial migration. We then examined individual steps of transmigration to explore the requirement for RhoA in extravasation. Our studies showed that RhoA was not required for monocyte attachment to the endothelium nor subsequent spreading of the monocyte on the endothelial surface. Time-lapse video microscopy analysis revealed that C3-loaded monocytes also had significant forward crawling movement on the endothelial monolayer and were able to invade between neighboring endothelial cells. However, RhoA was required to retract the tail of the migrating monocyte and complete diapedesis. We also demonstrate that p160ROCK, a serine/threonine kinase effector of RhoA, is both necessary and sufficient for RhoA-mediated tail retraction. Finally, we find that p160ROCK signaling negatively regulates integrin adhesions and that inhibition of RhoA results in an accumulation of β2 integrin in the unretracted tails.

Neuropeptide-stimulated cell migration in prostate cancer cells is mediated by RhoA kinase signaling and inhibited by neutral endopeptidase

“…RhoA is a monomeric GTPase that is required for migration in several cell types including neutrophils (Xu et al, 2003), monocytes (Worthylake et al, 2001) and fibroblasts (Sander et al, 1999). We have demonstrated that bombesin and ET-1 activate RhoA and that the RhoA effector, ROCK, is required for bombesinstimulated migration of PC cells.…”

The effects of modifying RhoA and Rac1 activities on heterotypic contact inhibition of locomotion

“…Lowering Rac1 activity resulted in an increase in RhoA activity and we found increased RhoA activity (V14RhoA) also gave rise to defective heterotypic CIL. RhoA was thought to be predominantly involved in tail retraction of migrating cells [24], however, recent studies suggest RhoA may participate in both membrane protrusion and retraction at the leading edge [20,25]. Cells expressing dominant active mDia became more invasive, possibly because mDia activates Rac1 [26].…”

C3 exoenzymes, novel insights into structure and action of Rho-ADP-ribosylating toxins

“…From a pathophysiological point of view it is important that C3 was shown to alter for example epithelial and endothelial barrier functions (Nusrat et al 1995;Stamatovic et al 2003), the signaling of immune cells including phagocytosis (Caron and Hall 1998), the production of cytokines (Chen et al 2002;Dreikhausen et al 2001), adhesion (Laudanna et al 1996), de-adhesion , and migration of immune cells (Worthylake et al 2001;Millan and Ridley 2005). A very recent study reported that C3stau-producing S. aureus form transcellular tunnels by inactivation of Rho, so-called macroapertures, which lead to the loss of barrier function in endothelial cells (Boyer et al 2006).…”