Spatial regulation of RhoC activity defines protrusion formation in migrating cells

Abstract

SummaryProtrusion formation is the first step that precedes cell movement of motile cells. Spatial control of actin polymerization is necessary to achieve directional protrusion during cell migration. Here we show that the spatial coordinators p190RhoGEF and p190RhoGAP regulate actin polymerization during leading edge protrusions by regulating the actin barbed end distribution and amplitude. The distribution of RhoC activity and proper balance of cofilin activation achieved by p190RhoGEF and p190RhoGAP determines the direction of final protrusive activity. These findings provide a new insight into the dynamic plasticity in the amplitude and distribution of barbed ends, which can be modulated by fine-tuning RhoC activity by upstream GEFs and GAPs for directed cell motility.

Rho GTPase isoforms in cell motility: Don't fret, we have FRET

“…In tumor cells it was also shown that in the absence of a lamellipodium, RhoA displayed high activation levels in mDia1-dependent finger like protrusions that formed after EGF stimulation. 49 Furthermore, biosensor technology has shown how RhoA activity is regulated in other cellular processes such as cytokinesis 50 and T-cell transendothelial migration. 51 The RhoA biosensor design has evolved since the first version 44,45 ( Fig.…”

“…57 The RhoC biosensor was used to reveal the mechanism by which RhoC contributes to the invasion of tumor cells. Spatial activation of RhoC surrounding the core of invasive protrusions named invadopodia 56 or within regions located behind the leading edge 49 triggers a signaling pathway that phosphorylates cofilin 58 and confines cofilin activity and actin polymerization at the core of invadopodia or to the tip of the leading edge, a localization which is essential for efficient invasion. These activation zones are regulated by the spatial and geometric arrangements of the direct upstream regulators p190RhoGEF and p190RhoGAP.…”

“…49,53,56 At invadopodia, RhoC has a geometrically confined activation pattern, while RhoA displays a more random activation pattern. 56 At leading edge protrusions, RhoC activation is confined spatially behind RhoA activation.…”

“…56 At leading edge protrusions, RhoC activation is confined spatially behind RhoA activation. 49 Also, using computational approaches in fibroblasts, the activation of RhoC was quantitatively compared with that of RhoA. 53 This analysis showed that areas of RhoC activation appeared to be more diffuse and evenly distributed at the edge of the cell.…”

“…These different activation dynamics suggest that the key determining factors that control subcellular GTPase activation dynamics is likely the spatial distribution of their upstream regulators. 49,56 Recent studies have also extended the use of Rho biosensors to in vivo systems. For example, Timpson et al, 59 have shown how RhoA activity is modulated in an animal model of pancreatic cancer using the fluorescence lifetime imaging (FLIM)-FRET measurements of the Raichu-RhoA biosensor.…”