探讨Rab26在香烟烟雾暴露致慢性阻塞性肺疾病(chronic obstructive pulmonary disease, COPD)气道上皮细胞衰老中的调控作用及分子机制。自噬功能异常是细胞衰老的重要特征，调整依赖Rab鸟苷三磷酸酶(guanosine triphosphatase, GTP)酶家族介导的囊泡运输过程。

采用香烟烟雾提取物(cigarette smoke extract, CSE)处理人支气管上皮细胞BEAS-2B，构建体外衰老模型，通过慢性香烟烟雾暴露构建COPD小鼠模型，选用6~8周龄雄性C57BL/6小鼠10只，分为暴露组(n＝5)和对照组(n＝5)。应用蛋白质印迹法、定量聚合酶链反应、免疫组织化学等检测Rab26、泛素特异性蛋白酶13(ubiquitin-specific protease 13, USP13)及衰老标志物p21。通过功能获得(过表达)和功能缺失(基因敲低)实验判断Rab26作用，利用转录组测序筛选下游靶点。

香烟烟雾暴露成功诱导气道上皮细胞衰老，小鼠肺组织及BEAS-2B细胞中衰老标志物p21蛋白表达显著上调，2% CSE处理9 d BEAS-2B细胞中p21蛋白表达升高(1.06比1.56)(P<0.01)，SA-β-gal阳性细胞比例同步增加。与对照组相比，烟雾暴露小鼠肺组织及2% CSE处理9 d的BEAS-2B细胞中Rab26在mRNA和蛋白水平下调，Rab26蛋白表达降低(0.79比0.33)(P<0.05)。功能获得实验中CSE处理条件下过表达Rab26显著抑制p21表达上调(2.27比1.36)(P<0.01)，减少SA-β-gal阳性细胞比例(P<0.01)。机制研究显示，USP13是Rab26调控气道上皮细胞衰老过程中重要下游关联分子，蛋白表达在烟雾暴露小鼠肺组织(0.94比0.57)、Rab26-/-小鼠肺组织中降低(0.90比0.64)(P<0.01)，在体外模型中过表达USP13可显著抑制CSE诱导的p21表达上调(P<0.01)，缓解细胞衰老表型。

Rab26通过USP13信号通路调控香烟烟雾诱导的气道上皮细胞衰老。

To investigate the regulatory role and molecular mechanism of Rab26 in airway epithelial cell senescence induced by cigarette smoke exposure in chronic obstructive pulmonary disease (COPD). Impaired autophagy is a key feature of cellular senescence, characterized by the dysregulation of vesicle transport processes dependent on the Rab GTPase family.

An in vitro senescence model was established by treating human bronchial epithelial cells BEAS-2B with cigarette smoke extract (CSE), COPD mouse models were generated by chronic cigarette smoke exposure. Ten male C57BL/6 mice aged 6~8 weeks were selected and divided into an exposure group (n=5) and a room air control group (n=5). Techniques such as Western blotting, quantitative polymerase chain reaction, and immunohistochemistry were employed to detect the expression of Rab26, ubiquitin-specific protease 13 (USP13), and the senescence marker p21. Gain-of-function (overexpression) and loss-of-function (gene knockdown) experiments were conducted to evaluate the role of Rab26, and transcriptome sequencing was used to screen its downstream targets.

Cigarette smoke exposure successfully induced airway epithelial cell senescence. In mouse lung tissues and BEAS-2B cells, the protein expression of the senescence marker p21 was significantly increased. Specifically, treatment of BEAS-2B cells with 2% CSE for 9 days increased p21 protein levels (1.06 vs. 1.56 )(P<0.01), accompanied by an increase in the proportion of SA-β-gal-positive cells. Compared with control groups, Rab26 expression was decreased at both the mRNA and protein levels in lung tissues from smoke-exposed mice and in BEAS-2B cells treated with 2% CSE for 9 days, with Rab26 protein levels reduced (0.79 vs. 0.33)(P<0.05). In gain-of-function experiments, overexpression of Rab26 under CSE exposure significantly attenuated the upregulation of p21 protein expression (2.27 vs. 1.36) (P<0.01) and reduced the proportion of SA-β-gal-positive cells (P<0.01). Further mechanistic analyses demonstrated that USP13 is an important downstream-associated molecule involved in Rab26-mediated regulation of airway epithelial cell senescence. USP13 protein expression was decreased(0.94 vs. 0.57) in lung tissues of smoke-exposed mice (P<0.01) and (0.90 vs. 0.64)in Rab26-/- mouse lung tissues (P<0.01). Moreover, in vitro overexpression of USP13 significantly suppressed CSE-induced p21 upregulation (P<0.01), thereby alleviating the senescent phenotype.

Rab26 regulates cigarette smoke-induced airway epithelial cell senescence through the USP13 signaling pathway.