Cancer-specific toxicity of apoptin is independent of death receptors but involves the loss of mitochondrial membrane potential and the release of mitochondrial cell-death mediators by a Nur77-dependent pathway
Cancer-specific toxicity of apoptin is independent of death receptors but involves the loss of mitochondrial membrane potential and the release of mitochondrial cell-death mediators by a Nur77-dependent pathway
复制标题
DOI：
10.1242/jcs.02580
复制
发表时间：
2005-10-01
影响因子：
4
通讯作者：
Los, M
中科院分区：
文献类型：
--
作者：
Maddika, S;Booy, EP;Los, M
细胞凋亡蛋白是一种源自鸡贫血病毒的富含脯氨酸的小蛋白，可选择性诱导癌细胞死亡。凋亡素诱导的癌细胞选择性凋亡的信号通路尚不清楚。在这里，我们证明凋亡素通过激活线粒体/内在途径触发细胞凋亡，并且其作用独立于死亡受体/外在途径。缺乏 FADD 或 caspase-8（两者都是外在途径所必需）的 Jurkat 细胞与它们的亲代克隆一样对凋亡素敏感。这表明凋亡素可能通过线粒体死亡途径发挥作用。凋亡素治疗会导致线粒体膜电位丧失，并释放线粒体蛋白细胞色素 c 和凋亡诱导因子。凋亡素诱导的细胞死亡被抗凋亡 Bcl-2 家族成员、Bcl-2 本身和 Bcl-X-L 抵消，如 Jurkat 白血病细胞中所示。此外，我们还描述了 caspase-3 的加工和激活。相比之下，没有观察到主要由死亡受体途径触发的 caspase-8 裂解。此外，凋亡素触发 Nur77 的细胞质易位，并且 siRNA 对 Nur77 表达的抑制显着保护 MCF7 细胞免于凋亡素触发的细胞死亡。因此，我们的数据表明凋亡素死亡信号最终汇聚于线粒体，并且其作用独立于死亡受体途径。
Apoptin, a small proline-rich protein derived from the chicken anaemia virus, induces cell death selectively in cancer cells. The signalling pathways of apoptin-induced, cancer cell-selective apoptosis are not well understood. Here, we demonstrate that apoptin triggers apoptosis by activating the mitochondrial/intrinsic pathway, and that it acts independently of the death receptor/extrinsic pathway. Jurkat cells deficient in either FADD or caspase-8 (which are both necessary for the extrinsic pathway) were equally as sensitive to apoptin as their parental clones. This demonstrates that apoptin is likely to act through the mitochondrial death pathway. Apoptin treatment causes a loss of mitochondrial membrane potential, and release of the mitochondrial proteins cytochrome c and apoptosis-inducing factor. Apoptin-induced cell death is counteracted by the anti-apoptotic Bcl-2 family members, Bcl-2 itself and Bcl-X-L, as shown in Jurkat leukaemia cells. In addition, we describe the processing and activation of caspase-3. By contrast, cleavage of caspase-8, which is predominantly triggered by the death receptor pathway, is not observed. Furthermore, apoptin triggers the cytoplasmic translocation of Nur77, and the inhibition of Nur77 expression by siRNA significantly protects MCF7 cells from apoptin-triggered cell death. Thus, our data indicate that the apoptin death signal(s) ultimately converges at the mitochondria, and that it acts independently of the death receptor pathway.