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Rnd3 modulates the balance of RhoA and Rac1 activity during thrombin‐induced hyperpermeability
Author(s) -
Kurtz Kristine M,
Doggett Travis M,
Breslin Jerome W
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.975.6
Subject(s) - rhoa , rac1 , thrombin , transfection , chemistry , cdc42 , microbiology and biotechnology , umbilical vein , gtpase , biochemistry , signal transduction , biology , platelet , immunology , in vitro , gene
We tested the hypothesis that Rnd3, an endogenous inhibitor of Rho, attenuates thrombin‐induced barrier dysfunction not by inhibiting Rho per se, but rather by affecting the collective balance of activity between RhoA, Rac1, and Cdc42. The signaling activity of these small GTPases was assessed in human umbilical vein endothelial cells (HUVEC) treated with thrombin (1U/ml) for 5, 30, 60, and 120 min. using the commercially available G‐LISA kit. HUVEC were mock‐transfected or transfected with pMAT‐FLAG‐Rnd3, Rnd3 siRNA, or siCONTROL RNA. The results show that although Rnd3 overexpression did not inhibit the initial (5 min.) activation of RhoA by thrombin, it did attenuate thrombin‐induced inhibition of Rac1 activity. Rnd3 knockdown extended the time course of RhoA activation by thrombin, but the time course of changes in Rac1 activity was not significantly affected. Thrombin did not significantly alter Cdc42 activity at any of the time points. The data indicate that Rnd3 is not simply an inhibitor of RhoA activity, but rather modulates the overall balance of small family GTPase activities, particularly between RhoA and Rac1. Supported by NIH RR018766 and a grant from the American Heart Association.