DNMTs甲基化修饰FAM8A1抑制ERAD调控慢性阻塞性肺疾病发病的作用机制研究

内质网应激及其诱导的细胞凋亡是慢阻肺机制研究的热点。内质网相关性降解途径（ERAD）是清除内质网错误折叠蛋白的主要机制。FAM8A1以复合体的形式在ERAD中起核心作用。我们前期研究发现，FAM8A1在慢阻肺中表达降低。在16HBE细胞中沉默FAM8A1会引起细胞凋亡。生物信息学分析示FAM8A1转录起始点上下游富含CpG岛，其可能受DNA甲基化调控。甲基转移酶家族（DNMTs）是催化DNA甲基化的关键酶。前期体外实验发现，香烟烟雾提取物能够诱导DNMTs的表达。故推测FAM8A1可能被DNMTs甲基化修饰调控，抑制其介导的ERAD，促进慢阻肺的发病。本课题拟通过临床样本验证FAM8A1表达，培养气道及肺泡上皮细胞阐述CSE通过DNMTs抑制FAM8A1表达及其介导ERAD的机制，建立慢阻肺大鼠模型明确FAM8A1介导的内质网稳态在肺上皮细胞凋亡中的保护性作用。为慢阻肺的治疗提供新方向。

Stress of the endoplasmic reticulum (ER) organelle, which is responsible for folding, processing, and trafficking of proteins in the cells is involved in the regulation of COPD pathogenesis. Imbalance in the ER load of misfolded proteins relative to ER folding capacity causes ER stress (ERS) and induces apoptosis which is the research hotspot in COPD. Misfolded ER proteins are removed by a process, called ER-associated protein degradation (ERAD), an evolutionarily conserved process in which substrates are retro-translocated into the cytosol, polyubiquitinated, and degraded by the proteasome. FAM8A1, a essential component in ubiquitin ligase complex, plays a central role in ERAD. We have found that FAM8A1 expressed lower in COPD than the non-COPD control group. Further silencing FAM8A1 in 16HBE cells induce cell apoptosis. Bioinformatics analysis showed that the upstream and downstream of FAM8A1 transcription start site was rich in CpG islands, which may be regulated by DNA methylation. Methyltransferase family (DNMTs) are key enzymes that catalyzes DNA methylation. The vitro experiments early suggested that cigarette smoke extract (CSE) induce the expression of DNMTs. We thus hypothesized that DNMTs methylation-modified FAM8A1 inhibits the ERAD and promote the development of COPD. This study intends to confirm the expression of FAM8A1 through clinical samples, explain the mechanism of CSE inhibiting FAM8A1 and FAM8A1-mediated ERAD through DNMTs in airway and alveolar epithelial cells , and establish a COPD rat model to clarify FAM8A1 mediated ER homeostasis preventing lung epithelial cells apoptosis, which provides a basis for improving the intervention strategy and developing new therapeutic targets for COPD treatment.