Substitution of the SERCA2 Cys674 reactive thiol accelerates
atherosclerosis by inducing endo-plasmic reticulum stress and
inflammation
Abstract
BACKGROUND AND PURPOSE The cysteine674 (C674) thiol of
Sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) is easily and
irreversibly oxidized under atherosclerotic conditions. However,
contribution of the C674 thiol redox status in the development of
atherosclerosis remains unclear. Our goal was to elucidate the possible
mechanism involved. EXPERIMENTAL APPROACH Heterozygous SERCA2 C674S
knock-in (SKI) mice in which half of the C674 was substituted by
serine674 were used to mimic removal of the reactive C674 thiol which
occurs under patholog-ical conditions. The whole aorta and aortic root
were isolated for histological analysis. Bone marrow derived macrophages
(BMDMs) and a cardiac endothelial cell line were used for intra-cellular
Ca2+, macrophage adhesion and protein expression analysis. KEY RESULTS
SKI mice developed more severe atherosclerotic plaque and macrophage
accumulation. Cell cul-ture studies suggest the partial substitution of
SERCA2 C674 increased intracellular calcium lev-els and ER stress in
both BMDMs and ECs. The release of pro-inflammatory factors and
macro-phage adhesion increased in SKI BMDMs. In normal ECs, the
overexpression of C674S mutant induced endothelial inflammation and
promoted macrophage recruitment. Additionally, 4-phenyl butyric acid
(4-PBA), an ER stress inhibitor, prevented the increased atherosclerosis
observed in SKI mice, and alleviated ER stress and inflammatory
responses in BMDMs and ECs exposed to 4-PBA. CONCLUSIONS AND
IMPLICATIONS The substitution of SERCA2 C674 thiol accelerates the
development of atherosclerosis by in-ducing ER stress and inflammation.
Our findings highlight the importance of SERCA2 C674 redox status in the
context of atherosclerosis, and open up a novel therapeutic strategy to
combat atherosclerosis.