Cross-talk between membrane fusion, cell cycle, and apoptosis

NSF-α-SNAP-SNARE复合物是一种涉及转运囊泡与其靶膜之间的膜融合的大蛋白复合物。我们最近发现了一种内质网（ER）陷阱，syntaxin 18，并证明该蛋白与ZW 10（一种参与纺锤体检查点的动粒蛋白），RINT-1（G2/M检查点蛋白）和BNIP 1（促凋亡BH 3-only家族的成员）形成复合物。本研究的目的是阐明通过syntaxin 18复合物在膜融合、细胞周期和凋亡之间相互作用的机制。1）syntaxin 18复合体各组分之间的相互作用双杂交分析显示syntaxin 18与p31、RINT-1与ZW 10、RINT-1与BNIP 1之间存在相互作用。RINT-1、ZW 10和p31形成一个亚复合体。2）ZW 10参与ER和Golgi之间的膜运输过表达、敲低和显微注射研究表明，ZW 10在间期在ER和Golgi之间的膜运输中起作用。3）BNIP 1在ER-ER膜融合中的意义发现BNIP 1参与ER-ER膜融合，而不是内质网和高尔基体之间的膜运输。结合研究表明，Leu-114是BNIP 1促凋亡BH 3结构域中高度保守的残基，对于与α-SNAP的相互作用是必需的，但与RINT-1的相互作用不是必需的。α-SNAP过表达显著延迟星形孢菌素诱导的细胞凋亡。这些结果提出了BNIP 1在膜融合和凋亡之间的串扰中起作用的可能性。

The NSF-α-SNAP-SNAREs complex is a large protein complex implicated in membrane fusion between transport vesicles and their target membranes. We have recently discovered an endoplasmic reticulum (ER) SNARE, syntaxin 18, and demonstrated that this protein forms a complex with ZW10 (a kinetochore protein involved in spindle checkpoint), RINT-1 (G2/M checkpoint protein), and BNIP1 (a member of the pro-apoptotic BH3-only family). The purpose of this research is to elucidate the mechanisms underlying cross-talk between membrane fusion, cell-cycle, and apoptosis via the syntaxin 18 complex. The following results have been obtained.1)Interactions between components of the syntaxin 18 complexTwo-hybrid analysis revealed the interactions between syntaxin 18 and p31, RINT-1 and ZW10, and RINT-1 and BNIP1. RINT-1, ZW10 and p31 form a sub-complex.2)Involvement of ZW10 in membrane traffic between the ER and GolgiOverexpression, knockdown, and microinjection studies revealed that ZW10 in the interphase plays a role in membrane trafficking between the ER and Golgi.3)Implication of BNIP1 in ER-ER membrane fusionBNIP1 was found to participate in ER-ER membrane fusion, rather than membrane transport between the ER and Golgi. Binding studies revealed that Leu-114, a highly conserved residue in the pro-apoptotic BH3 domain of BNIP1, is essential for the interaction with α-SNAP but not with RINT-1. Overexpression of α-SNAP markedly delayed staurosporine-induced apoptosis. These results raise the possibility that BNIP1 functions in cross-talk between membrane fusion and apoptosis.