Rationale:Vascular smooth muscle cells (SMCs) exhibit remarkable plasticity and can undergo dedifferentiation upon pathological stimuli associated with disease and interventions.Objective:Although epigenetic changes are critical in SMC phenotype switching, a fundamental regulator that governs the epigenetic machineries regulating the fate of SMC phenotype has not been elucidated.Methods and Results:Using SMCs, mouse models, and human atherosclerosis specimens, we found that FAK (focal adhesion kinase) activation elicits SMC dedifferentiation by stabilizing DNMT3A (DNA methyltransferase 3A). FAK in SMCs is activated in the cytoplasm upon serum stimulation in vitro or vessel injury and active FAK prevents DNMT3A from nuclear FAK-mediated degradation. However, pharmacological or genetic FAK catalytic inhibition forced FAK nuclear localization, which reduced DNMT3A protein via enhanced ubiquitination and proteasomal degradation. Reduced DNMT3A protein led to DNA hypomethylation in contractile gene promoters, which increased SMC contractile protein expression. RNA-sequencing identified SMC contractile genes as a foremost upregulated group by FAK inhibition from injured femoral artery samples compared with vehicle group. DNMT3A knockdown in injured arteries reduced DNA methylation and enhanced contractile gene expression supports the notion that nuclear FAK-mediated DNMT3A degradation via E3 ligase TRAF6 (TNF [tumor necrosis factor] receptor-associated factor 6) drives differentiation of SMCs. Furthermore, we observed that SMCs of human atherosclerotic lesions exhibited decreased nuclear FAK, which was associated with increased DNMT3A levels and decreased contractile gene expression.Conclusions:This study reveals that nuclear FAK induced by FAK catalytic inhibition specifically suppresses DNMT3A expression in injured vessels resulting in maintaining SMC differentiation by promoting the contractile gene expression. Thus, FAK inhibitors may provide a new treatment option to block SMC phenotypic switching during vascular remodeling and atherosclerosis.

中文翻译：

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FAK 激活通过增加收缩基因中的 DNA 甲基化促进 SMC 去分化

基本原理：血管平滑肌细胞 (SMC) 表现出显着的可塑性，并且可以在与疾病和干预相关的病理刺激下发生去分化。目的：尽管表观遗传变化在 SMC 表型转换中至关重要，但这是一种控制表观遗传机制的基本调节因子，可调节 SMC 的命运表型尚未阐明。方法和结果：使用 SMC、小鼠模型和人类动脉粥样硬化标本，我们发现 FAK（粘着斑激酶）激活通过稳定 DNMT3A（DNA 甲基转移酶 3A）引发 SMC 去分化。SMC 中的 FAK 在体外血清刺激或血管损伤后在细胞质中被激活，活性 FAK 可防止 DNMT3A 发生核 FAK 介导的降解。然而，药理学或遗传 FAK 催化抑制迫使 FAK 核定位，通过增强泛素化和蛋白酶体降解减少 DNMT3A 蛋白。减少的 DNMT3A 蛋白导致收缩基因启动子中的 DNA 低甲基化，从而增加了 SMC 收缩蛋白的表达。与媒介物组相比，RNA 测序将 SMC 收缩基因鉴定为通过 FAK 抑制从受伤的股动脉样本中最重要的上调组。受损动脉中的 DNMT3A 敲低减少了 DNA 甲基化并增强了收缩基因表达，这支持了核 FAK 介导的 DNMT3A 降解通过 E3 连接酶 TRAF6（TNF [肿瘤坏死因子] 受体相关因子 6）驱动 SMC 分化的观点。此外，我们观察到人类动脉粥样硬化病变的 SMC 表现出核​​ FAK 减少，这与 DNMT3A 水平增加和收缩基因表达减少有关。结论：本研究表明，FAK 催化抑制诱导的核 FAK 特异性抑制受损血管中的 DNMT3A 表达，从而通过促进收缩基因表达来维持 SMC 分化。因此，FAK 抑制剂可能提供一种新的治疗选择，以阻断血管重塑和动脉粥样硬化期间的 SMC 表型转换。