Panaretakis Theocharis, Kepp Oliver, Brockmeier Ulf, Tesniere Antoine, Bjorklund Ann-Charlotte, Chapman Daniel C, Durchschlag Michael, Joza Nicholas, Pierron Gérard, van Endert Peter, Yuan Junying, Zitvogel Laurence, Madeo Frank, Williams David B, Kroemer Guido
INSERM, Unit 848, Villejuif, France.
EMBO J. 2009 Mar 4;28(5):578-90. doi: 10.1038/emboj.2009.1. Epub 2009 Jan 22.
Dying tumour cells can elicit a potent anticancer immune response by exposing the calreticulin (CRT)/ERp57 complex on the cell surface before the cells manifest any signs of apoptosis. Here, we enumerate elements of the pathway that mediates pre-apoptotic CRT/ERp57 exposure in response to several immunogenic anticancer agents. Early activation of the endoplasmic reticulum (ER)-sessile kinase PERK leads to phosphorylation of the translation initiation factor eIF2alpha, followed by partial activation of caspase-8 (but not caspase-3), caspase-8-mediated cleavage of the ER protein BAP31 and conformational activation of Bax and Bak. Finally, a pool of CRT that has transited the Golgi apparatus is secreted by SNARE-dependent exocytosis. Knock-in mutation of eIF2alpha (to make it non-phosphorylatable) or BAP31 (to render it uncleavable), depletion of PERK, caspase-8, BAP31, Bax, Bak or SNAREs abolished CRT/ERp57 exposure induced by anthracyclines, oxaliplatin and ultraviolet C light. Depletion of PERK, caspase-8 or SNAREs had no effect on cell death induced by anthracyclines, yet abolished the immunogenicity of cell death, which could be restored by absorbing recombinant CRT to the cell surface.
垂死的肿瘤细胞可通过在细胞出现任何凋亡迹象之前将钙网蛋白（CRT）/内质网蛋白57（ERp57）复合物暴露于细胞表面，引发强大的抗癌免疫反应。在此，我们列举了在响应几种免疫原性抗癌药物时介导凋亡前CRT/ERp57暴露的信号通路中的各个元件。内质网（ER）驻留激酶PERK的早期激活导致翻译起始因子eIF2α磷酸化，随后半胱天冬酶-8（而非半胱天冬酶-3）部分激活，半胱天冬酶-8介导内质网蛋白BAP31的裂解以及Bax和Bak的构象激活。最后，一批已通过高尔基体转运的CRT通过SNARE依赖性胞吐作用分泌出去。eIF2α的敲入突变（使其不可磷酸化）或BAP31的敲入突变（使其不可裂解）、PERK、半胱天冬酶-8、BAP31、Bax、Bak或SNAREs的缺失消除了蒽环类药物、奥沙利铂和紫外线C诱导的CRT/ERp57暴露。PERK、半胱天冬酶-8或SNAREs的缺失对蒽环类药物诱导的细胞死亡没有影响，但消除了细胞死亡的免疫原性，而通过将重组CRT吸附到细胞表面可恢复这种免疫原性。
