Fluid shear stress induces the phosphorylation of small heat shock
proteins in vascular endothelial cells.
Li, S., R. S. Piotrowicz, E. G. Levin, Y. J. Shyy, and S. Chien.
Department of Bioengineering and Institute for Biomedical
Engineering, University of California San Diego, La Jolla,
California, Department of Molecular and Experimental Medicine, The
Scripps Research Institute, La Jolla, California
APStracts 3:0106C, 1996.
The small molecular weight heat shock protein HSP27 has been shown to
influence actin filament dynamics and endothelial cell behavior in
ways similar to those observed during laminar flow. We have employed
human umbilical vein endothelial cells (HUVEC) to determine whether
fluid shear stress affects HSP27 expression or phosphorylation.
Following a shear stress of 16 dyne/cm2, HSP27 became more highly
phosphorylated with maximum increase in phosphorylation levels (3
-fold) attained by 30 min and sustained for at least 20 hr. HSP27
antigen levels did not change; however, HSP27 mRNA levels decreased
by 20% after 16?hr. In bovine aorta endothelial cells (BAEC) stably
transfected with the wild type human HSP27 gene, shear stress induced
the phosphorylation of both the exogenous human HSP27 and the
endogenous bovine HSP25. The product of a transfected mutant HSP27
gene in which the putative phosphorylation sites Ser-15, Ser-78, and
Ser-82 had been replaced with Gly was not phosphorylated. Thus, the
modulation of HSP27 and its activity by shear stress is mediated
through a post-translational mechanism, and differs from the shear
stress induction of immediate early genes at the level of
transcription.
Received 14 December 1995; accepted in final form 25 March 1996.
APS Manuscript Number C746-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96