Phospholipase C epsilon suppresses integrin activation.
Phospholipase Cepsilon (PLCepsilon) is a newly described effector of the small GTP-binding protein H-Ras. Utilizing H-Ras effector mutants, we show that mutants H-Ras(G12V/E37G) and H-Ras(G12V/D38N) suppressed integrin activation in an ERK-independent manner. H-Ras(G12V/D38N) specifically activated the PLCepsilon effector pathway and suppressed integrin activation. Inhibition of PLCepsilon activation with a kinase-dead PLCepsilon mutant prevented H-Ras(G12V/D38N) from suppressing integrin activation, and low level expression of H-Ras(G12V/D38N) could synergize with wild-type PLCepsilon to suppress integrins. In addition, knockdown of endogenous PLCepsilon with small interfering RNA blocked H-Ras(G12V/D38N)-mediated integrin suppression. Suppressing integrin function with the H-Ras(G12V/D38N) mutant reduced cell adhesion to von Willebrand factor and fibronectin; this reduction in cell adhesion was blocked by coexpression of the kinase-dead PLCepsilon mutant. These results show that H-Ras suppresses integrin affinity via independent Raf and PLCepsilon signaling pathways and demonstrate a new physiological function for PLCepsilon in the regulation of integrin activation.
Lad
Yatish
Y
Medical Research Council Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4SA, Scotland, United Kingdom.
McHugh
Brian
B
Hodkinson
Philip S
PS
Mackinnon
Alison C
AC
Haslett
Christopher
C
Ginsberg
Mark H
MH
Sethi
Tariq
T
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D015536:Down-Regulation / Q000235:genetics; D005998:Glycine / Q000235:genetics; D016023:Integrins / Q000378:metabolism*; D054801:Phosphoinositide Phospholipase C; D051381:Rats; D012694:Serine / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D013912:Threonine / Q000235:genetics; D010738:Type C Phospholipases / Q000235:genetics / Q000502:physiology*; D014633:Valine / Q000235:genetics; D018631:ras Proteins / Q000502:physiology
D016023:Integrins; D013912:Threonine; D012694:Serine; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; C423320:phospholipase C epsilon; D018631:ras Proteins; D014633:Valine; D005998:Glycine