Martinez-Arca Sonia, Proux-Gillardeaux Veronique, Alberts Philipp, Louvard Daniel, Galli Thierry
Membrane Traffic and Neuronal Plasticity, INSERM U536, Institut du Fer-à-Moulin, 75005 Paris, France.
J Cell Sci. 2003 Jul 1;116(Pt 13):2805-16. doi: 10.1242/jcs.00467. Epub 2003 May 20.
SNARE proteins are key mediators of membrane fusion. Their function in ensuring compartmental specificity of membrane fusion has been suggested by in vitro studies but not demonstrated in vivo. We show here that ectopic expression of the plasma membrane t-SNARE heavy chain syntaxin 1 in the endoplasmic reticulum induces the redistribution of its cognate vesicular SNAREs, TI-VAMP and cellubrevin, and its light chain t-SNARE SNAP-23. These effects were prevented by co-expressing nSec1. Expression of syntaxin 1 alone impaired the cell surface expression of TI-VAMP and cellubrevin but not the recycling of transferrin receptor. TI-VAMP, cellubrevin and SNAP-23 associated in vivo with exogenous syntaxin 1. Redistribution of TI-VAMP in the ER of syntaxin-1-expressing cells was microtubule dependent and impaired the trafficking of CD63, a cargo of TI-VAMP-containing vesicles. We conclude that the destination of v-SNAREs is driven by their specific interaction with cognate t-SNAREs. Our in vivo data provide strong support for the theory that highly specific v-SNARE-t-SNARE interactions control compartmental specificity of membrane fusion.
SNARE蛋白是膜融合的关键介质。体外研究表明了它们在确保膜融合的区室特异性方面的功能，但尚未在体内得到证实。我们在此表明，内质网中质膜t-SNARE重链 syntaxin 1的异位表达会诱导其同源囊泡SNAREs（TI-VAMP和细胞ubrevin）及其轻链t-SNARE SNAP-23的重新分布。共表达nSec1可防止这些效应。单独表达syntaxin 1会损害TI-VAMP和细胞ubrevin的细胞表面表达，但不会影响转铁蛋白受体的循环利用。TI-VAMP、细胞ubrevin和SNAP-23在体内与外源性syntaxin 1相关联。TI-VAMP在表达syntaxin-1的细胞内质网中的重新分布依赖于微管，并损害了CD63（一种含TI-VAMP囊泡的货物）的运输。我们得出结论，v-SNAREs的目的地是由它们与同源t-SNAREs的特异性相互作用驱动的。我们的体内数据为高度特异性的v-SNARE-t-SNARE相互作用控制膜融合的区室特异性这一理论提供了有力支持。
