PTEN promoter hypermethylation underlies vascular disease progression

摘要 动脉粥样硬化和再狭窄分别是慢性和急性炎症性血管疾病， 其特征是显着的血管重塑。常驻血管平滑肌细胞的表型转换 （SMC）在重塑中发挥着独特而关键的作用，是促进疾病进展的关键事件。同时 SMC表型调节的概念，其特征是从分化的收缩表型转变为 去分化、促炎表型已被广泛接受，调节这些 SMC 的机制 过渡是复杂的。重要的是，没有任何治疗方法可以防止 SMC 收缩性的丧失 表型和炎症增加。我们之前确定 PTEN 在调节中至关重要 病理性血管重塑。 PTEN 失活会促进去分化、炎症性 SMC 表型。 最近，我们定义了核 PTEN 的一个完全独特且重要的功能，作为转录辅助因子。 具有 SRF 的因子，SRF 是调节 SMC 收缩基因的主转录因子和 SMC 特异性 miR-143/145 表达及其肌肉特异性辅助因子心肌素。 PTEN 丢失阻止 SRF-心肌素转录 活动。具有转化意义，该活性在正常和患病的人类冠状动脉中得到证实 我们确定 PTEN 缺失与 SMC 去分化和动脉粥样硬化进展直接相关 和复杂性。在这种情况下介导 PTEN 丢失的机制尚不清楚。我们最近展示了 全身性 PTEN 升高会减弱血管紧张素 II (AngII) 介导的血管重塑和纤维化并阻断 动脉粥样硬化病变进展和损伤介导的新内膜形成；这些影响与 保持收缩性 SMC 表型和减少炎症微环境。因此，我们的数据 支持 PTEN 通过直接转录控制是分化 SMC 表型的重要驱动因素 SMC 收缩基因的变化和促炎表型的抑制，表明系统性 PTEN 上调足以预防血管疾病进展。最近的无偏高通量筛选 旨在发现新型 PTEN 小分子激活剂的研究表明，DNA 甲基转移酶 1 (DNMT1) 抑制剂 5-氮杂胞苷 (5-aza) 在转录水平上强力上调 PTEN，逆转 PDGF介导的SMC去分化和DNA甲基胞嘧啶脱氧酶、TET2和的抑制 阻断病理性血管重塑。重要的是，这些体外和体内效应都是通过 PTEN。我们认为 PTEN 基因的高甲基化是减少 PTEN 的重要机制 水平并促进病理性血管重塑（目标一）。此外，我们建议血管 5-aza介导的保护作用是通过增加PTEN表达、PTEN之间的串扰来驱动的 和 TET2，以及 miR-143/145 的下游调节（目标二）。最后，我们建议增加PTEN 启动子高甲基化与动脉粥样硬化进展加剧、DNMT1 上调和 患病人类血管中 TET2 的下调（目标三）。

ABSTRACT Atherosclerosis and restenosis are chronic and acute inflammatory vascular diseases, respectively, characterized by significant vascular remodeling. Phenotypic switching of resident vascular smooth muscle cells (SMCs) plays a unique and critical role in remodeling and is a key event promoting disease progression. While the concept of SMC phenotypic modulation, marked by a shift from a differentiated, contractile phenotype to a dedifferentiated, pro-inflammatory phenotype, is well-accepted, the mechanisms regulating these SMC transitions are complex. Importantly, there are no therapeutics that prevent both the loss of the SMC contractile phenotype and increased inflammation. We previously established that PTEN is critical in the regulation of pathological vascular remodeling. PTEN inactivation promotes a dedifferentiated, inflammatory SMC phenotype. More recently, we defined an entirely unique and essential function for nuclear PTEN as a transcriptional co- factor with SRF, a master transcription factor regulating SMC contractile gene and SMC-specific miR-143/145 expression, and its muscle-specific cofactor, myocardin. PTEN loss prevents SRF-myocardin transcriptional activity. Translationally significant, this activity was confirmed in normal and diseased human coronary arteries as we established that PTEN loss directly correlated with SMC dedifferentiation and atherosclerosis progression and complexity. The mechanism mediating loss of PTEN in this setting was unclear. We recently demonstrated that systemic PTEN elevation blunts angiotensin II (AngII)-mediated vascular remodeling and fibrosis and blocks atherosclerotic lesion progression and injury-mediated neointima formation; these effects are associated with preservation of a contractile SMC phenotype and a reduced inflammatory microenvironment. Thus, our data support that PTEN is an essential driver of the differentiated SMC phenotype through direct transcriptional control of SMC contractile genes and repression of a proinflammatory phenotype and indicate that systemic PTEN upregulation is sufficient to prevent vascular disease progression. A recent unbiased high throughput screen designed to discover novel small molecule activators of PTEN revealed that the DNA methyltransferase 1 (DNMT1) inhibitor, 5-azacytidine (5-aza), robustly upregulates PTEN at the level of transcription, reverses PDGF-mediated SMC dedifferentiation and repression of the DNA methylcytosine deoxygenase, TET2, and blocks pathological vascular remodeling. Importantly, these effects both in vitro and in vivo are mediated via PTEN. We propose that hypermethylation of the PTEN gene is an essential mechanism that reduces PTEN levels and promotes pathological vascular remodeling (Aim One). In addition, we propose that the vascular protective effects mediated by 5-aza are driven through increased PTEN expression, crosstalk between PTEN and TET2, and downstream regulation of miR-143/145 (Aim Two). Finally, we propose that increased PTEN promoter hypermethylation correlates with increased atherosclerosis progression, upregulation of DNMT1, and downregulation of TET2 in diseased human vessels (Aim Three).