Cardiovascular Research Advance Access [Accepted Manuscript] published online on September 24, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn262
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Salvianolic Acid B protects human endothelial cells from oxidative stress damage: a possible protective role of GRP78 induction
a Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100083, P. R. China
b National Research Institute for Family Planning, Beijing 100081, P. R. China
c State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100083, PR China
* Corresponding Author: Xue-Jun Li, Ph.D. Department of Pharmacology School of Basic Medical Sciences Peking University Health Science Center Beijing, China 10083 Phone: 861082802863 FAX: 861082802863 Email: xjli{at}bjmu.edu.cn
Aims: The purposes of the present study were to both evaluate the protective effects of Salvianolic acid B (Sal B) and to determine the possible molecular mechanisms by which Sal B protects endothelial cells from damage caused by oxidative stress.
Methods and results: Pretreatment with Sal B markedly attenuated H2O2-induced viability loss, lactate dehydrogenase (LDH) leakage and apoptosis in human umbilical vein endothelial cells (HUVECs). The mechanism of Sal B protection was studied using two-dimensional gel electrophoresis coupled with hybrid quadrupole time-of-flight (Q-TOF) mass spectrometry. Database searching implicated that glucose-regulated protein 78 (GRP78), a central regulator for endoplasmic reticulum (ER) stress, was up-regulated in Sal B-exposed HUVECs. GRP78 expression regulation was confirmed by Western blot and RT-PCR analyses. Additionally, GRP94, which shares significant sequence homology with GRP78, was also upregulated in Sal B-treated cells. Sal B caused pancreatic ER kinase (PKR)-like ER kinase (PERK) activation followed by the phosphorylation of eukaryotic translation initiation factor 2
(eIF2) and the expression of activating transcription factor 4 (ATF4). Knockdown of endogenous ATF4 expression partially repressed Sal B-induced GRP78 induction. Further investigation showed that ATF6 was also activated by Sal B. Knock-down of GRP78 by siRNA significantly reduced the protective effects of Sal B.
Conclusion: The results suggest that Sal B induces the expression of GRP78 by activating ATF6 and the PERK-eIF2a-ATF4 pathway. Furthermore, up-regulation of GRP78 by Sal B may play an important role in protecting human endothelial cells from oxidative stress-induced cellular damage.
KEYWORDS salvianolic acid B; oxidative stress; endothelial cell; GRP78; endoplasmic reticulum stress
Time for primary review: 44 days