Department of Biochemistry, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore, Singapore.
J Cell Physiol. 2012 Dec;227(12):3722-30. doi: 10.1002/jcp.24082.
Dogmatic views of how proteins and other cellular components may traffic within and between eukaryotic cells have been challenged in the past few years. Beyond the classical secretory/exocytic pathway and its established players, other pathways of cell surface membrane transport, generally termed "unconventional secretion," are now better understood. More insights have also been gleaned on the roles of secreted or shedding microvesicles, either exosomal or ectosomal in origin, in unconventional secretion. Recent works have also revealed key molecular components, particularly the Golgi reassembly stacking protein (GRASP), and the importance of stress-induced autophagy, in unconventional exocytic transport. This GRASP and autophagy-dependent (GAD) mode appears to underlie the unconventional exocytosis of many soluble and membrane cargoes. Likewise, recent findings have revealed transport processes that contrast the classically known mitochondria import, namely vesicular transport from the mitochondria to peroxisomes and lysosomes. Mitochondria-peroxisomal targeting of mitochondria-derived vesicles appears to involve the retromer complex, which was classically associated with endosome-Golgi membrane traffic. The routes of intracellular membrane transport and communications between eukaryotic organelles now appear far more complex that one would have imagined 10 years ago.
在过去的几年中，人们对蛋白质和其他细胞成分在真核细胞内和细胞间运输的教条式观点提出了挑战。除了经典的分泌/胞吐途径及其已确立的参与者外，其他细胞膜运输途径，通常称为“非常规分泌”，现在得到了更好的理解。关于起源于外泌体或ectosome 的分泌或脱落的微泡（microvesicles）在非常规分泌中的作用，也有了更多的了解。最近的研究还揭示了关键的分子成分，特别是高尔基再组装堆积蛋白（GRASP），以及应激诱导的自噬在非常规胞吐作用中的重要性。这种 GRASP 和自噬依赖性（GAD）模式似乎是许多可溶性和膜货物非常规胞吐的基础。同样，最近的发现揭示了与经典的线粒体导入相反的运输过程，即从线粒体到过氧化物酶体和溶酶体的囊泡运输。线粒体衍生囊泡的线粒体-过氧化物酶体靶向似乎涉及到 retromer 复合物，该复合物经典上与内体-高尔基体膜运输有关。真核细胞器之间的细胞内膜运输和通讯途径现在似乎比 10 年前人们想象的要复杂得多。
