The YAP-TEAD complex promotes senescent cell survival by lowering endoplasmic reticulum stress [bulk RNA-seq]

Sublethal cell damage can trigger a complex adaptive program known as senescence, characterized by growth arrest, resistance to apoptosis, and a senescence-associated secretory phenotype (SASP). As senescent cells accumulating in aging organs are linked to many age-associated diseases, senotherapeutic strategies are actively sought to eliminate them. Here, a whole-genome CRISPR knockout screen revealed that proteins in the YAP-TEAD pathway influenced senescent cell viability. Accordingly, treating senescent cells with a drug that inhibited this pathway, Verteporfin (VPF), selectively triggered apoptotic cell death and derepressed DDIT4, in turn inhibiting mTOR. Reducing mTOR function in senescent cells diminished endoplasmic reticulum (ER) biogenesis, causing ER stress and apoptosis due to high demands on ER function by the SASP. Importantly, VPF treatment decreased senescent cell numbers in the organs of old mice and mice exhibiting doxorubicin-induced senescence. We present a novel senolytic strategy that eliminates senescent cells by hindering ER activity required for SASP production. RNA-sequencing analysis of WI-38 human diploid fibroblasts with three independent replicates per group: Etoposide-induced senescent (ETIS) cells were obtained by treatment with 50 μM etoposide for 6 days, and treated with verteporfin (VPF, 1.5 μM) or vehicle (0.3% DMSO) for 48 hours, while proliferating cells treated with vehicle were included as controls.

亚致死细胞损伤可触发一种名为细胞衰老（senescence）的复杂适应性程序，其特征为生长停滞、抗凋亡特性以及衰老相关分泌表型（SASP）。由于在衰老器官中聚集的衰老细胞与诸多年龄相关性疾病密切相关，当前学界正积极探索用于清除这类细胞的衰老治疗策略。本研究通过全基因组CRISPR敲除筛选发现，YAP-TEAD通路中的蛋白质可影响衰老细胞的存活能力。据此，使用靶向抑制该通路的药物维替泊芬（Verteporfin, VPF）处理衰老细胞，可选择性诱导其凋亡，并解除DDIT4的表达抑制，进而抑制哺乳动物雷帕霉素靶蛋白（mTOR）。在衰老细胞中削弱mTOR功能会减少内质网（ER）的生物合成，由于SASP对ER功能存在高度依赖，这会引发内质网应激与细胞凋亡。值得注意的是，VPF处理可降低老年小鼠以及阿霉素诱导衰老模型小鼠器官内的衰老细胞数量。本研究提出了一种全新的衰老清除策略：通过阻断SASP生成所需的ER活性以清除衰老细胞。本研究对WI-38人二倍体成纤维细胞开展了转录组测序分析，每组设置3次独立生物学重复：依托泊苷诱导衰老（ETIS）细胞通过50 μM依托泊苷处理6天获得，随后分别用1.5 μM维替泊芬（VPF）或溶剂对照（0.3% DMSO）处理48小时；同时设置仅用溶剂处理的增殖细胞作为对照组。