Department of Biochemistry and Cell Biology, Guarini School of Graduate and Advanced Studies, Hanover, NH 03755, USA.
Department of Biochemistry and Cell Biology, Guarini School of Graduate and Advanced Studies, Hanover, NH 03755, USA
J Cell Sci. 2021 Mar 26;134(6):jcs249276. doi: 10.1242/jcs.249276.
A genome-wide screen recently identified SEC24A as a novel mediator of thapsigargin-induced cell death in HAP1 cells. Here, we determined the cellular mechanism and specificity of SEC24A-mediated cytotoxicity. Measurement of Ca levels using organelle-specific fluorescent indicator dyes showed that Ca efflux from endoplasmic reticulum (ER) and influx into mitochondria were significantly impaired in -knockout cells. Furthermore, knockout cells also showed ∼44% less colocalization of mitochondria and peripheral tubular ER. Knockout of , but not its paralogs , or , rescued HAP1 cells from cell death induced by three different inhibitors of sarcoplasmic/endoplasmic reticulum Ca ATPases (SERCA) but not from cell death induced by a topoisomerase inhibitor. Thapsigargin-treated -knockout cells showed a ∼2.5-fold increase in autophagic flux and ∼10-fold reduction in apoptosis compared to wild-type cells. Taken together, our findings indicate that SEC24A plays a previously unrecognized role in regulating association and Ca flux between the ER and mitochondria, thereby impacting processes dependent on mitochondrial Ca levels, including autophagy and apoptosis.
最近的全基因组筛选鉴定 SEC24A 是 HAP1 细胞中他普西龙诱导细胞死亡的一种新型介质。在这里，我们确定了 SEC24A 介导的细胞毒性的细胞机制和特异性。使用细胞器特异性荧光指示剂染料测量 Ca 水平表明，内质网（ER）中 Ca 的流出和线粒体中 Ca 的流入在 -敲除细胞中显著受损。此外，敲除细胞的线粒体和周围管状 ER 的共定位也减少了约 44%。敲除 ，但不是其同源物 、 或 ，可挽救 HAP1 细胞免于三种不同的肌浆/内质网 Ca2+-ATP 酶（SERCA）抑制剂诱导的细胞死亡，但不能挽救拓扑异构酶抑制剂诱导的细胞死亡。与野生型细胞相比，他普西龙处理的 -敲除细胞中的自噬流增加了约 2.5 倍，凋亡减少了约 10 倍。总之，我们的研究结果表明，SEC24A 在调节内质网和线粒体之间的关联和 Ca 流方面发挥了以前未被认识的作用，从而影响了依赖线粒体 Ca 水平的过程，包括自噬和凋亡。
