Signalling and function of the small Rho GTPase RhoJ in endothelial cells

RhoJ is an endothelial expressed Rho GTPase, and its knock-down impairs endothelial cell (EC) migration and tubulogenesis, increases stress fibre (SF) and focal adhesion (FA) numbers. This work aimed to determine the intracellular localisation of RhoJ, identify its binding partners, test how it is activated and further explore its function in ECs. Endogenous RhoJ localised to FAs and overexpression of its active mutant (daRhoJ) promoted EC migration, and diminished FA and SF numbers. In addition to FAs, overexpressed RhoJ localised also to endosomes and RhoJ knock-down slightly delayed transferrin recycling. Vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF-2) and thrombin activated RhoJ in ECs. PAK-interacting exchange factor β (βPIX) and G protein-coupled receptor kinase-interacting target 1 (GIT1), which promote FA disassembly, were identified as RhoJ-binding partners. RhoJ co-localised with these proteins in ECs, and βPIX knock-down and to a lesser extent GIT1 knock-down reduced RhoJ localisation to FAs. Overexpression of daRhoJ increased the amount of GIT1 and βPIX in FAs, and increased the total amount of the βPIX protein in ECs. In conclusion, RhoJ localises to FAs, promotes EC migration, regulates FA and SF numbers, interacts with βPIX and GIT1 and is activated by pro-angiogenic factors.

Name dc:type.qualificationname

d_ph

Level dc:type.qualificationlevel

d_ph

Grantor dc:publisher.institution

University of Birmingham

Year dc:date.issued

2011

Author dc:creator

• Leszczynska, Katarzyna

• QR180 Immunology