Abstract
Background and aimsAtherogenesis involves a complex interaction between immune cells and lipids, processes greatly influenced by the vascular smooth muscle cell (VSMC) phenotype. The DNA glycosylase NEIL3 has previously been shown to have a role in atherogenesis, though whether this is due to its ability to repair DNA damage or to other non-canonical functions is not yet clear. Hereby, we investigate the role of NEIL3 in atherogenesis, specifically in VSMC phenotypic modulation, which is critical in plaque formation and stability. MethodsChow diet-fed atherosclerosis-prone Apoe−/− mice deficient in Neil3, and NEIL3-abrogated human primary aortic VSMCs were characterized by qPCR, and immunohistochemical and enzymatic-based assays; moreover, single-cell RNA sequencing, mRNA sequencing, and proteomics were used to map the molecular effects of Neil3/NEIL3 deficiency in the aortic VSMC phenotype. Furthermore, BrdU-based proliferation assays and Western blot were performed to elucidate the involvement of the Akt signaling pathway in the transdifferentiation of aortic VSMCs lacking Neil3/NEIL3. ResultsWe show that Neil3 deficiency increases atherosclerotic plaque development without affecting systemic lipids. This observation was associated with a shift in VSMC phenotype towards a proliferating, lipid-accumulating and secretory macrophage-like cell phenotype, without changes in DNA damage. VSMC transdifferentiation in Neil3-deficient mice encompassed increased activity of the Akt signaling pathway, supported by cell experiments showing Akt-dependent proliferation in NEIL3-abrogated human primary aortic VSMCs. ConclusionsOur findings show that Neil3 deficiency promotes atherosclerosis development through non-canonical mechanisms affecting VSMC phenotype involving activation of the Akt signaling pathway.
Highlights
Despite great improvement in the treatment of heart and stroke disease, atherosclerosis remains the leading cause of death and loss of productive life years worldwide [1]
NEIL3 KD-human aortic VSMCs (HaoVSMC) displayed increased secretion of matrix metalloproteinase (MMP)-2, a major player in plaque progression and destabilization (Fig. 2C) [24], as well as increased lipid uptake compared to controls (Fig. 2D-F), suggesting a phenotypic shift at the functional level. These findings indicate that NEIL3 deficiency drives vascular smooth muscle cell (VSMC) towards a more macrophage-like cell phenotype, which could contribute to atheroscle rotic plaque progression
We show that Neil3 deficiency in Apoe− /− mice on chow diet markedly increased plaque development in the aortic root without affecting the systemic lipid and cytokine profile
Summary
Despite great improvement in the treatment of heart and stroke disease, atherosclerosis remains the leading cause of death and loss of productive life years worldwide [1] Common risk factors such as smoking, hyperlipidemia and obesity [2] trigger sustained injury to both circulating and vascular cells that initiate and accelerate the atherogenic process, with inflammation and immune activation as common mediators. We elucidated the function of Neil in the development of atherosclerosis and explored the role of Neil3/NEIL3 in VSMC proliferation and phenotypic switch in Apoe− /− /Neil3− /− mice exposed to a chow diet. Results: We show that Neil deficiency increases atherosclerotic plaque development without affecting systemic lipids This observation was associated with a shift in VSMC phenotype towards a proliferating, lipidaccumulating and secretory macrophage-like cell phenotype, without changes in DNA damage.
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