Mol. Cell. Biol., 11 1996, 5947-5954, Vol 16, No. 11
YS Li, JY Shyy, S Li, J Lee, B Su, M Karin and S Chien
Hemodynamic forces play a key role in inducing atherosclerosis- implicated
gene expression in vascular endothelial cells. To elucidate the signal
transduction pathway leading to such gene expression, we studied the
effects of fluid shearing on the activities of upstream signaling
molecules. Fluid shearing (shear stress, 12 dynes/cm2 [1 dyne = 10(-5)N])
induced a transient and rapid activation of p21ras and preferentially
activated c-Jun NH2 terminal kinases (JNK1 and JNK2) over extracellular
signal-regulated kinases (ERK-1 and ERK-2). Cotransfection of RasN17, a
dominant negative mutant of Ha-Ras, attenuated the shear-activated JNK and
luciferase reporters driven by
12-O-tetradecanoylphorbol-13-acetate-responsive elements. JNK(K-R) and
MEKK(K-M), the respective catalytically inactive mutants of JNK1 and MEKK,
also partially inhibited the shear-induced luciferase reporters. In
contrast, Raf301, ERK(K71R), and ERK(K52R), the dominant negative mutants
of Raf-1, ERK-1, and ERK-2, respectively, had little effect on the
activities of these reporters. The activation of JNK was also correlated
with increased c-Jun transcriptional activity, which was attenuated by a
negative mutant of Son of sevenless. Thus, mechanical stimulation exerted
by fluid shearing activates primarily the Ras-MEKK- JNK pathway in inducing
endothelial gene expression.
Copyright © 1996, American Society for Microbiology
The Ras-JNK pathway is involved in shear-induced gene expression
Department of Bioengineering, Institute for Biomedical Engineering, University of California, San Diego, La Jolla 92093, USA.
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