Tetanus toxin-mediated cleavage of cellubrevin impairs exocytosis of transferrin receptor-containing vesicles in CHO cells.
Tetanus toxin-mediated cleavage of cellubrevin impairs exocytosis of transferrin receptor-containing vesicles in CHO cells.
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DOI：
10.1083/jcb.125.5.1015
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发表时间：
1994-06
影响因子：
7.8
通讯作者：
De Camilli, P
中科院分区：
文献类型：
--
作者：
Galli, T;Chilcote, T;Mundigl, O;Binz, T;Niemann, H;De Camilli, P
Cellubrevin是SNARS家族突触素/VAMP家族的成员，具有广泛的组织分布。在成纤维细胞中，它集中在回收转铁蛋白受体的囊泡中，但它在膜转运和融合中的作用仍有待证实。Cellubrevin和突触小泡蛋白Synaptobrevins I和Synaptobrevins II一样，可以被破伤风毒素切割，破伤风毒素是一种金属内蛋白酶，可以阻止神经递质的释放。然而，由于其重链缺乏细胞表面受体，非神经细胞不受毒素的影响。为了确定细胞短链蛋白裂解是否损害循环小泡的胞吐功能，我们测试了破伤风毒素轻链对链溶素-O穿孔CHO细胞释放预内化转铁蛋白的影响。药物的释放不仅对NEM敏感，而且依赖于温度和ATP。加入破伤风毒素轻链，但不是蛋白水解性非活性形式的毒素，导致部分抑制转铁蛋白的释放，这与毒素介导的细胞短链切割有关。转铁蛋白在细胞短素完全降解后的残留释放仍然依赖于ATP。我们的结果表明，细胞素在回收质膜受体的囊泡的结构性胞吐过程中起着重要作用。这种毒素对转铁蛋白释放的不完全抑制表明存在一种不依赖于破伤风毒素的胞吐机制，这可能涉及到突触素/VAMP家族中的破伤风毒素不敏感蛋白。
Cellubrevin is a member of the synaptobrevin/VAMP family of SNAREs, which has a broad tissue distribution. In fibroblastic cells it is concentrated in the vesicles which recycle transferrin receptors but its role in membrane trafficking and fusion remains to be demonstrated. Cellubrevin, like the synaptic vesicle proteins synaptobrevins I and II, can be cleaved by tetanus toxin, a metallo-endoprotease which blocks neurotransmitter release. However, nonneuronal cells are unaffected by the toxin due to lack of cell surface receptors for its heavy chain. To determine whether cellubrevin cleavage impairs exocytosis of recycling vesicles, we tested the effect of tetanus toxin light chain on the release of preinternalized transferrin from streptolysin-O-perforated CHO cells. The release was found to be temperature and ATP dependent as well as NEM sensitive. Addition of tetanus toxin light chain, but not of a proteolytically inactive form of the toxin, resulted in a partial inhibition of transferrin release which correlated with the toxin-mediated cleavage of cellubrevin. The residual release of transferrin occurring after complete cellubrevin degradation was still ATP dependent. Our results indicate that cellubrevin plays an important role in the constitutive exocytosis of vesicles which recycle plasmalemma receptors. The incomplete inhibition of transferrin release produced by the toxin suggests the existence of a cellubrevin-independent exocytotic mechanism, which may involve tetanus toxin-insensitive proteins of the synaptobrevin/VAMP family.