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

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

Vascular smooth muscle cells (VSMCs) play a critical role in regulating vasotone, and their phenotypic plasticity is a key contributor to the pathogenesis of various vascular diseases. Two main VSMC phenotypes have been well described: contractile and synthetic. Contractile VSMCs are typically found in the tunica media of the vessel wall, and are responsible for regulating vascular tone and diameter. Synthetic VSMCs, on the other hand, are typically found in the tunica intima and adventitia, and are involved in vascular repair and remodeling. Switching between contractile and synthetic phenotypes occurs in response to various insults and stimuli, such as injury or inflammation, and this allows VSMCs to adapt to changing environmental cues and regulate vascular tone, growth, and repair. Furthermore, VSMCs can also switch to osteoblast-like and chondrocyte-like cell phenotypes, which may contribute to vascular calcification and other pathological processes like the formation of atherosclerotic plaques. This provides discusses the mechanisms that regulate VSMC phenotypic switching and its role in the development of vascular diseases. A better understanding of these processes is essential for the development of effective diagnostic and therapeutic strategies.

S-adenosylmethionine attenuates angiotensin II-induced aortic dissection formation by inhibiting vascular smooth muscle cell phenotypic switch and autophagy

It is well known that aortic dissection (AD) is a very aggressive class of vascular diseases. S-adenosylmethionine (SAM) is an autophagy inhibitor with anti-inflammatory and anti-oxidative stress effects; however, the role of SAM in AD is unknown. In this study, we constructed an animal model of AD using subcutaneous minipump continuous infusion of AngII-induced ApoE-/-mice and a cytopathic model using AngII-induced primary vascular smooth muscle cells (VSMCs) to investigate the possible role of SAM in AD. The results showed that mice in the AngII + SAM group had significantly lower AD incidence, significantly prolonged survival, and reduced vascular elastic fiber disruption compared with mice in the AngII group. In addition, SAM significantly inhibited autophagy in vivo and in vitro. Meanwhile, SAM also inhibited the cellular phenotypic switch, mainly by up regulating the expression levels of contractile marker proteins [α-smooth muscle actin (α-SMA) and smooth muscle 22α (SM22α)] and down regulating the expression levels of synthetic marker proteins [osteoblast protein (OPN), matrix metalloproteinase-2 (MMP2), and matrix metalloproteinase-9 (MMP9)]. Molecularly, SAM inhibited AD formation mainly by activating the PI3K/AKT/mTOR signaling pathway. Using a PI3K inhibitor (LY294002) significantly reversed the protective effect of SAM in AngII-induced mice and VSMCs.Our study demonstrates the protective effect of SAM on mice under AngII-induced AD for the first time. SAM prevented AD formation mainly by inhibiting cellular phenotypic switch and autophagy, and activation of the PI3K/AKT/mTOR signaling pathway is a possible molecular mechanism. Thus, SAM may be a novel strategy for the treatment of AD.

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

ABSTRACT

We investigated the clinical characteristics of patients with acute aortic dissection (AAD) and miR-590-3p levels in serum, tissue, and vascular smooth muscle cells. The effect of miR-590-3p on the vascular smooth muscle cell phenotype was assessed, and the regulation of lysyl oxidase by miR-5903p was determined. C57BL/6 mice were used to investigate the incidence of AAD and effects of miR-5903p on AAD. The miR-590-3p levels were measured in the aortae of mice, and hematoxylin and eosin staining and Masson staining were performed to identify the morphological features of the aorta. Comparative analysis revealed significant differences in clinical characteristics between patients with AAD and healthy control subjects, with most patients with AAD exhibiting concomitant hypertension and nearly 50% having atherosclerosis. Lysyl oxidase was a direct target of miR-590-3p. Lysyl oxidase overexpression inhibited switching of the vascular smooth muscle cell phenotype from contractile to synthetic, but miR-590-3p overexpression significantly reversed this change. In the mouse model, miR-590-3p upregulation increased the incidence of AAD to 93.3%, and its incidence decreased to 13.3% after miR-590-3p inhibition. Hematoxylin and eosin and Masson staining revealed that the miR-590-3p agomiR group had a greater loss of the contractile phenotype in the dissected aortic wall and an increased number of muscle fibers in the aortic wall, which contributed to thickening of the aortic wall and the formation of a false lumen in aortic dissection. miR-590-3p might be pivotal in the pathogenesis of AAD. Thus, targeting miR-590-3p or its downstream pathways could represent a therapeutic approach for AAD.