C/EBPα-Mediated Transcriptional Activation of PIK3C2A Regulates Autophagy, Matrix Metalloproteinase Expression, and Phenotypic of Vascular Smooth Muscle Cells in Aortic Dissection

Abstract

Purpose. To investigate the function of C/EBPα in the development of aortic dissection (AD) and the underlying mechanism. Methods. Aortic vascular smooth muscle cells (VSMCs) were isolated, cultured, and identified from AD rats. Then, C/EBPα and PIK3C2A were knockdown or overexpressed by siRNA or plasmid transfection, respectively. Rapamycin or 3-MA was utilized to stimulate and restrain autophagy of VSMCs, respectively. Western blot was used to evaluate the expression levels of C/EBPα, PIK3C2A, LC3, Beclin-1, p62, MMP-2, MMP-9, α-SMA, SM-MHC, and OPN. The pathological status of aortic ring was evaluated by stretch stress, and ChIP assay was used to analyze the binding between C/EBPα and PIK3C2A. C/EBPα shRNA was injected into tail vein to observe the effect of C/EBPα knockdown in vivo on phenotype, autophagy of aortic vascular tissue by immunohistochemical staining and Western blot. Results. The protein levels of C/EBPα, PIK3C2A, MMP-2, MMP-9, and LC3 in the aorta of AD rats were all upregulated significantly. C/EBPα and rapamycin promoted notable upregulation of the synthesized proteins (OPN), PIK3C2A, matrix metalloproteinases, LC3, and Beclin-1 in VSMCs, while suppressed contractile proteins (α-SMA and SM-MHC) and p62. The opposite results were observed in the C/EBPα-knockdown VSMCs, PIK3C2A-knockdown VSMCs, or VSMCs treated with 3-MA. C/EBPα, PIK3C2A, and LC3 were dramatically upregulated by the stimulation of 3 g and 5 g stretch stress. The downregulated contractile proteins, upregulated synthetic proteins, activated autophagy, and aggravated pathological state in 5 g stretch stress-treated aortic rings were significantly reversed by the knockdown of C/EBPα. ChIP results indicated that there was a binding site for C/EBPα in the promoter of PIK3C2A. C/EBPα also downregulated α-SMA level and upregulated OPN levels in AD rats in vivo. Conclusion. Our data indicated that during the development of AD, C/EBPα regulated the transition of VSMC phenotype and extracellular matrix remodeling by activating autophagy through regulating the transcriptional activity of PIK3C2A promoter.

Phenotypic switching of vascular smooth muscle cells in atherosclerosis, hypertension, and aortic dissection

“…Indeed, during the progression of aortic dissection, the balance between contractile and synthetic VSMCs is shifted toward synthetic VSMCs with increased proteolytic enzyme production by those VSMCs, as depicted in Figure 4. Additionally, VSMCs in the medial layer of the aortic wall in aortic dissection patients show decreased contractile function and increased proliferation and migration (Lu et al, 2022; Zhang et al, 2013).…”

“…Phenotypic switching is implicated in numerous vascular diseases including atherosclerosis, hypertension, and aortic dissection (Coll‐Bonfill et al, 2016; Gomes et al, 2017; Lu et al, 2022; Mosse et al, 1985; Napoli et al, 1997; Zhang et al, 2013). This switching, shown in Figure 1, is associated with reduced expression of SMC‐specific markers, and a shift from spindle‐shaped to epithelial‐like morphology (Bochaton‐Piallat et al, 1996).…”

MiR-590-3p Promotes the Phenotypic Switching of Vascular Smooth Muscle Cells by Targeting Lysyl Oxidase

“…8,9 Some inflammatory factors, including matrix metalloproteinases and vascular smooth muscle cell (VSMC) phenotypic transition, are significantly involved in the pathogenesis of AD. 10 VSMCs reside in the medial layer of major blood vessels, where their contractility controls the vascular tone and blood distribution. 11 Injury, inflammation, and oxidative stress induce VSMC phenotypic switching, followed by the downregulation of contractile-related markers (eg, MYH11, ACTA2), increases in the extracellular matrix (ECM) component synthesis capacity, and the enhancement of proliferation and migration.…”