RhoG regulates endothelial apical cup assembly downstream from ICAM1 engagement and is involved in leukocyte trans-endothelial migration.
During trans-endothelial migration (TEM), leukocytes use adhesion receptors such as intercellular adhesion molecule-1 (ICAM1) to adhere to the endothelium. In response to this interaction, the endothelium throws up dynamic membrane protrusions, forming a cup that partially surrounds the adherent leukocyte. Little is known about the signaling pathways that regulate cup formation. In this study, we show that RhoG is activated downstream from ICAM1 engagement. This activation requires the intracellular domain of ICAM1. ICAM1 colocalizes with RhoG and binds to the RhoG-specific SH3-containing guanine-nucleotide exchange factor (SGEF). The SH3 domain of SGEF mediates this interaction. Depletion of endothelial RhoG by small interfering RNA does not affect leukocyte adhesion but decreases cup formation and inhibits leukocyte TEM. Silencing SGEF also results in a substantial reduction in RhoG activity, cup formation, and TEM. Together, these results identify a new signaling pathway involving RhoG and its exchange factor SGEF downstream from ICAM1 that is critical for leukocyte TEM.
van Buul
Jaap D
JD
Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA. j.vanbuul@sanquin.nl
Allingham
Michael J
MJ
Samson
Thomas
T
Meller
Julia
J
Boulter
Etienne
E
García-Mata
Rafael
R
Burridge
Keith
K
D000818:Animals; D019556:COS Cells; D002448:Cell Adhesion; D002465:Cell Movement; D016764:Cell Polarity; D022081:Cell Surface Extensions / Q000378:metabolism; D002522:Chlorocebus aethiops; D042783:Endothelial Cells / Q000166:cytology* / Q000201:enzymology*; D004789:Enzyme Activation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000737:chemistry / Q000378:metabolism*; D007962:Leukocytes / Q000166:cytology* / Q000201:enzymology / Q000648:ultrastructure; D008863:Microspheres; D011485:Protein Binding; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D018909:src Homology Domains
C473930:ARHGEF26 protein, human; D020662:Guanine Nucleotide Exchange Factors; D011993:Recombinant Fusion Proteins; D018799:Intercellular Adhesion Molecule-1; D049452:Green Fluorescent Proteins; C075397:RHOG protein, human; D020741:rho GTP-Binding Proteins