Background and Purpose
Inactivation of Cys674 (C674) in the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) causes intracellular Ca2+ accumulation, which activates calcineurin‐mediated nuclear factor of activated T‐lymphocytes (NFAT)/NF‐κB pathways, and results in the phenotypic modulation of smooth muscle cells (SMCs) to accelerate angiotensin II‐induced aortic aneurysms. Our goal was to investigate the mechanism involved.
Experimental Approach
We used heterozygous SERCA2 C674S knock‐in (SKI) mice, where half of C674 was substituted by serine, to mimic partial irreversible oxidation of C674. The aortas of SKI mice and their littermate wild‐type mice were collected for RNA sequencing, cell culture, protein expression, luciferase activity and aortic aneurysm analysis.
Key Results
Inactivation of C674 inhibited the promoter activity and protein expression of PPARγ, which could be reversed by inhibitors of calcineurin or NF‐κB. In SKI SMCs, inhibition of NF‐κB by pyrrolidinedithiocarbamic acid (PDTC) or overexpression of PPARγ2 reversed the protein expression of SMC phenotypic modulation markers and inhibited cell proliferation, migration, and macrophage adhesion to SMCs. Pioglitazone, a PPARγ agonist, blocked the activation of NFAT/NF‐κB, reversed the protein expression of SMC phenotypic modulation markers, and inhibited cell proliferation, migration, and macrophage adhesion to SMCs in SKI SMCs. Furthermore, pioglitazone also ameliorated angiotensin II‐induced aortic aneurysms in SKI mice.
Conclusions and Implications
The inactivation of SERCA2 C674 promotes the development of aortic aneurysms by disrupting the balance between PPARγ and NFAT/NF‐κB. Our study highlights the importance of C674 redox status in regulating PPARγ to maintain aortic homeostasis.
Background and Purpose: The Cys 674 residue (C674) in the sarcoplasmic/ endoplasmic reticulum Ca 2+ ATPase 2 (SERCA2) is key to maintaining its enzyme activity. The irreversible oxidation of C674 occurs broadly in aortic aneurysms. Substitution of C674 promotes a phenotypic transition of aortic smooth muscle cells (SMCs) and exacerbates angiotensin II-induced aortic aneurysm. However, its underlying mechanism remains enigmatic.Experimental Approach: Heterozygous SERCA2 C674S knock-in (SKI) mice, in which half of C674 was replaced by serine, were used to mimic partially irreversible oxidation of C674 thiol. The aortas of SKI mice and their littermate wild-type mice under an LDL receptor-deficient background were collected for histological and immunohistochemical analysis. Cultured aortic SMCs were used for protein expression, apoptosis analysis, and cell function studies.
This a preprint and has not been peer reviewed. Data may be preliminary. (SMCs) to accelerate angiotensin II-induced aortic aneurysm. Our goal was to investigate the mechanism involved. Experimental Approach We used heterozygous SERCA2 C674S knock-in (SKI) mice, where half of C674 was substituted by serine, to represent partial irreversible oxidation of C674. The aortas of SKI mice and their littermate wild-type mice were collected for RNA sequencing, cell culture, protein expression, luciferase activity and aortic aneurysm analysis.
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