Epigenetic Regulation of Phenotypic Plasticity of Vascular Smooth Muscle Cells

血管平滑肌细胞表型可塑性的表观遗传调控

• 批准号: RGPIN-2020-04592
• 负责人: Zheng, XiLong
• 金额: $ 2.62万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740062
• 关键词: Epigenetic; Regulation; Phenotypic; Plasticity; Vascular

Vascular smooth muscle cells (SMCs) are not terminally differentiated and have phenotypic plasticity: differentiated, contractile SMCs can undergo dedifferentiation and become synthetic and proliferative, and vice versa. Myocardin, a transcriptional coactivator of serum response factor (SRF), controls the expression of SMC contractile proteins and microRNAs (miRs) to promote SMC differentiation and inhibit cell proliferation. Many factors including hormones, growth factors and cytokines regulate SMC plasticity, but how they trigger intracellular signaling to confer phenotypic switching is poorly understood. Evidence suggests that epigenetic modification participates in SMC phenotype regulation. DNA methylation, for example, inhibits myocardin gene expression. DNA methylation and demethylation are catalyzed by methyltransferases (DNMT1, 3A, 3B) and ten-eleven translocation (TET1, 2, 3) enzymes, respectively. Myocardin is associated with demethylation of its target genes, in which TET2 binds to CArG boxes in the promoters. However, the exact mechanisms underlying epigenetic regulation of SMC phenotypes remain largely unknown. Rationale and hypothesis. Our preliminary results showed a role for DNA methylation in myocardin expression and functions. Our previous findings also revealed myocardin induction of miR-1 expression and inhibition of cell proliferation. Therefore, we hypothesize that myocardin gene methylation and demethylation determines myocardin gene expression and that myocardin also induces DNA demethylation of its target genes, driving SMC differentiation and inhibiting cell proliferation. Objectives. To test the above hypotheses, we set up two aims over 5 years: 1) Investigate the roles for myocardin gene methylation and demethylation in SMC phenotypic plasticity. We expect to discover or reveal the specific DNMTs and TETs that dictate the DNA methylation level of the myocardin gene, contributing to the regulation of SMC phenotypic plasticity. 2) Determine how myocardin modulates DNA methylation of its target genes, including SM contractile proteins and miRs. We expect to reveal myocardin induction of demethylation of its target genes, such as SM contractile proteins and miRs, and the underlying mechanisms. Significance. Our studies will uncover a novel epigenetic mechanism underlying SMC phenotypic plasticity, representing a major advancement in vascular biology.

血管平滑肌细胞 (SMC) 不是终末分化的，具有表型可塑性：分化的、有收缩性的 SMC 可以经历去分化并变得合成和增殖，反之亦然。心肌素是血清反应因子 (SRF) 的转录共激活剂，控制 SMC 收缩蛋白和 microRNA (miR) 的表达，以促进 SMC 分化并抑制细胞增殖。包括激素、生长因子和细胞因子在内的许多因素调节 SMC 可塑性，但人们对它们如何触发细胞内信号传导以赋予表型转换知之甚少。有证据表明表观遗传修饰参与 SMC 表型调节。例如，DNA 甲基化会抑制心肌素基因表达。 DNA 甲基化和去甲基化分别由甲基转移酶 (DNMT1、3A、3B) 和 10-11 易位 (TET1、2、3) 酶催化。心肌素与其靶基因的去甲基化有关，其中 TET2 与启动子中的 CArG 盒结合。然而，SMC 表型表观遗传调控的确切机制仍然很大程度上未知。 基本原理和假设。我们的初步结果表明 DNA 甲基化在心肌素表达和功能中发挥作用。我们之前的研究结果还揭示了心肌素诱导 miR-1 表达并抑制细胞增殖。因此，我们推测心肌素基因的甲基化和去甲基化决定了心肌素基因的表达，并且心肌素还诱导其靶基因DNA去甲基化，驱动SMC分化并抑制细胞增殖。 目标。为了检验上述假设，我们在 5 年内设定了两个目标：1）研究心肌素基因甲基化和去甲基化在 SMC 表型可塑性中的作用。我们期望发现或揭示决定心肌素基因 DNA 甲基化水平的特定 DNMT 和 TET，从而有助于调节 SMC 表型可塑性。 2) 确定心肌素如何调节其靶基因（包括 SM 收缩蛋白和 miR）的 DNA 甲基化。我们期望揭示心肌素诱导其靶基因（例如 SM 收缩蛋白和 miR）去甲基化及其潜在机制。意义。我们的研究将揭示 SMC 表型可塑性背后的一种新的表观遗传机制，代表着血管生物学的重大进步。