肿瘤组织中的浸润淋巴细胞 (TIL)的数量和质量与肿瘤的预后密切相关。 TIL 杀伤肿瘤的最主要的机制是 PFP/ Gr B途径。穿孔素 (PFP)通过在靶细胞膜上形成活性孔道使靶细胞渗透压改变而溶解 ,或者与颗粒酶协同作用而诱导靶细胞凋亡。本...肿瘤组织中的浸润淋巴细胞 (TIL)的数量和质量与肿瘤的预后密切相关。 TIL 杀伤肿瘤的最主要的机制是 PFP/ Gr B途径。穿孔素 (PFP)通过在靶细胞膜上形成活性孔道使靶细胞渗透压改变而溶解 ,或者与颗粒酶协同作用而诱导靶细胞凋亡。本文概述了穿孔素和颗粒酶的一般性质、作用机制。展开更多
Exocytosis of mam maUan sperm dense-core secretory granule relies on the same fusion molecules as all other secretory cells; one such molecule is the small GTPase Rab3A. Here, we report an in-depth biochemical charact...Exocytosis of mam maUan sperm dense-core secretory granule relies on the same fusion molecules as all other secretory cells; one such molecule is the small GTPase Rab3A. Here, we report an in-depth biochemical characterization of the role of Rab3A in secretion by scrutinizingthe exocytotic response of streptolysin O-permeabiUzed human sperm to the acute application of a number of Rab3A-containing constructs and correlating the findings with those gathered with the endogenous protein. Full length, geranyigeranyiated, and active Rab3A elicited human sperm exocytosis perse. With Rab3A/Rab22A chimeric proteins, we demonstrated that the carboxy-terminal domain of the Rab3A molecule was necessary and sufficient to promote exocytosis, whereas its amino.terminus prevented calcium-triggered secretion. Interestingly, full length Rab3A halted secretion when added after the docking of the acrosome to the plasma membrane. This effect depended on the inability of Rab3A to hydrolyze GTP. We combined modified immunofluorescence and acrosomal staining protocols to detect membrane fusion and the activation status of endogenous Rab3 simultaneously in individual cells, and found that GTP hydrolysis on endogenous Rab3 was mandatory for fusion pores to open. Our findings contribute to establishing that Rab3 modulates regulated exocytosis differently depending on the nucleotide bound and the exocytosis stage under study.展开更多
文摘Exocytosis of mam maUan sperm dense-core secretory granule relies on the same fusion molecules as all other secretory cells; one such molecule is the small GTPase Rab3A. Here, we report an in-depth biochemical characterization of the role of Rab3A in secretion by scrutinizingthe exocytotic response of streptolysin O-permeabiUzed human sperm to the acute application of a number of Rab3A-containing constructs and correlating the findings with those gathered with the endogenous protein. Full length, geranyigeranyiated, and active Rab3A elicited human sperm exocytosis perse. With Rab3A/Rab22A chimeric proteins, we demonstrated that the carboxy-terminal domain of the Rab3A molecule was necessary and sufficient to promote exocytosis, whereas its amino.terminus prevented calcium-triggered secretion. Interestingly, full length Rab3A halted secretion when added after the docking of the acrosome to the plasma membrane. This effect depended on the inability of Rab3A to hydrolyze GTP. We combined modified immunofluorescence and acrosomal staining protocols to detect membrane fusion and the activation status of endogenous Rab3 simultaneously in individual cells, and found that GTP hydrolysis on endogenous Rab3 was mandatory for fusion pores to open. Our findings contribute to establishing that Rab3 modulates regulated exocytosis differently depending on the nucleotide bound and the exocytosis stage under study.
