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， 其特征在于显著的血管重塑。驻留血管平滑肌细胞的表型转换 平滑肌细胞（SMCs）在重塑中起着独特而关键的作用，是促进疾病进展的关键事件。而 SMC表型调节的概念，其标志是从分化的收缩表型转变为 去分化，促炎表型，是公认的，调节这些SMC的机制 过渡是复杂的。重要的是，没有治疗方法既能防止平滑肌细胞收缩功能的丧失， 表型和炎症增加。我们先前已经确定，PTEN在调节细胞凋亡中是至关重要的。 病理性血管重塑PTEN失活促进去分化的炎性SMC表型。 最近，我们定义了一个完全独特的和必要的功能，核PTEN作为一个转录的共同， SMC收缩基因调控主转录因子SRF和SMC特异性miR-143/145 表达，以及其肌肉特异性辅因子，心肌素。PTEN缺失阻止SRF-心肌蛋白转录 活动具有翻译意义的是，这种活性在正常和患病的人冠状动脉中得到证实 因为我们确定了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 系统性PTEN升高减弱血管紧张素II（AngII）介导的血管重塑和纤维化， 动脉粥样硬化病变进展和损伤介导的新生内膜形成;这些效应与 保持收缩性SMC表型和减少的炎症微环境。因此，我们的数据 支持PTEN是通过直接转录控制分化SMC表型的基本驱动因素 平滑肌细胞收缩基因的表达和促炎表型的抑制，表明系统性PTEN 上调足以防止血管疾病进展。最近的无偏高通量筛选 旨在发现新的小分子PTEN激活剂的研究表明，DNA甲基转移酶1 （DNMT 1）抑制剂5-氮杂胞苷（5-aza）在转录水平上稳健地上调PTEN，逆转 PDGF介导的SMC去分化和DNA甲基胞嘧啶脱氧酶、TET 2和 阻止病理性血管重塑重要的是，体外和体内的这些作用均通过以下途径介导： PTEN。我们认为PTEN基因的高甲基化是减少PTEN表达的重要机制。 水平和促进病理性血管重塑（目的一）。此外，我们建议， 由5-aza介导的保护作用是通过增加PTEN表达，PTEN之间的串扰， 和TET 2，以及miR-143/145的下游调控（目的二）。最后，我们提出增加的PTEN 启动子超甲基化与动脉粥样硬化进展增加、DNMT 1上调和 在患病的人血管中下调TET 2（目的三）。

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).