Department of Breast Surgery, Second Hospital of Jilin University, Changchun, China.
Department of Radiotherapy, China-Japan Union Hospital of Jilin University, Changchun, China.
Sci Rep. 2022 Aug 29;12(1):14675. doi: 10.1038/s41598-022-19066-y.
Shikonin induces glioma cell death via necroptosis, a caspase-independent programmed cell death pathway that is chiefly regulated by receptor-interacting serine/threonine protein kinase1 (RIP1) and 3 (RIP3). Chromatinolysis is considered as one of the key events leading to cell death during necroptosis. It is usually accompanied with nuclear translocation of AIF and formation of γ-H2AX. Cyclophilin A (CypA) is reported to participate in the nuclear translocation of AIF during apoptosis. However, it remains unclear whether CypA contributes to necroptosis and regulation of chromatinolysis. In this study, our results revealed for the first time that shikonin promoted time-dependent CypA activation, which contributed to nuclear translocation of AIF and γ-H2AX formation. In vitro studies showed that knockdown of CypA by siRNA or inhibition of CypA by its specific inhibitor, cyclosporine A (CsA), not only significantly mitigated shikonin-induced glioma cell death, but also prevented chromatinolysis. Mechanistically, activated CypA targeted mitochondria and triggered mitochondrial superoxide overproduction, which then promoted AIF translocation from mitochondria into the nucleus by depolarizing the mitochondria and intensified the formation of γ-H2AX by promoting intracellular accumulation of ROS. Additionally, the CypA in the nucleus can form DNA degradation complexes with AIF and γ-H2AX, which also promote the execution of chromatinolysis. Thus, we demonstrate that CypA contributes to shikonin-induced glioma cell necroptosis and promotion of chromatinolysis.
紫草素通过坏死性细胞死亡途径诱导神经胶质瘤细胞死亡，这种细胞死亡途径是一种不依赖半胱天冬酶的程序性细胞死亡途径，主要受受体相互作用丝氨酸/苏氨酸蛋白激酶 1（RIP1）和 3（RIP3）的调节。染色质溶解被认为是坏死性细胞死亡过程中导致细胞死亡的关键事件之一。它通常伴随着 AIF 的核转位和γ-H2AX 的形成。细胞色素 P450 A（CypA）被报道在细胞凋亡过程中参与 AIF 的核转位。然而，目前尚不清楚 CypA 是否参与坏死性细胞死亡和染色质溶解的调节。在这项研究中，我们的结果首次揭示，紫草素促进 CypA 的时间依赖性激活，这有助于 AIF 和γ-H2AX 的核转位。体外研究表明，通过 siRNA 敲低 CypA 或其特异性抑制剂环孢菌素 A（CsA）抑制 CypA，不仅显著减轻紫草素诱导的神经胶质瘤细胞死亡，而且阻止染色质溶解。机制上，激活的 CypA 靶向线粒体并引发线粒体中超氧阴离子的过度产生，从而通过去极化线粒体和通过促进 ROS 在内质网中的积累来增强γ-H2AX 的形成，从而促进 AIF 从线粒体向细胞核的易位。此外，核中的 CypA 可以与 AIF 和γ-H2AX 形成 DNA 降解复合物，这也促进了染色质溶解的执行。因此，我们证明 CypA 有助于紫草素诱导的神经胶质瘤细胞坏死性细胞死亡和促进染色质溶解。
