Mora R, Bonilha V L, Marmorstein A, Scherer P E, Brown D, Lisanti M P, Rodriguez-Boulan E
Dyson Vision Research Institute, Department of Ophthalmology, and Department of Cell Biology, Weill Medical College of Cornell University, New York 10021, USA.
J Biol Chem. 1999 Sep 3;274(36):25708-17. doi: 10.1074/jbc.274.36.25708.
We have characterized comparatively the subcellular distributions of caveolins-1 and -2, their interactions and their roles in caveolar formation in polarized epithelial cells. In Fischer rat thyroid (FRT) cells, which express low levels of caveolin-2 and no caveolin-1, caveolin-2 localizes exclusively to the Golgi complex but is partially redistributed to the plasma membrane upon co-expression of caveolin-1 by transfection or by adenovirus-mediated transduction. In Madin-Darby canine kidney (MDCK) cells, which constitutively express both caveolin-1 and -2, caveolin-2 localized to both the Golgi complex and to the plasma membrane, where it co-distributed with caveolin-1 in flat patches and in caveolae. In FRT cells, endogenous or overexpressed caveolin-2 did not associate with low density Triton insoluble membranes that floated in sucrose density gradients but was recruited to these membranes when co-expressed together with caveolin-1. In MDCK cells, both caveolin-1 and caveolin-2 associated with low density Triton-insoluble membranes. In FRT cells, transfection of caveolin-1 promoted the assembly of plasma membrane caveolae that localized preferentially (over 99%) to the basolateral surface, like constitutive caveolae of MDCK cells. In contrast, as expected from its intracellular distribution, endogenous or overexpressed caveolin-2 did not promote the assembly of caveolae; rather, it appeared to promote the assembly of intracellular vesicles in the peri-Golgi area. The data reported here demonstrate that caveolin-1 and -2 have different and complementary subcellular localizations and functional properties in polarized epithelial cells and suggest that the two proteins co-operate to carry out specific as yet unknown tasks between the Golgi complex and the cell surface.
我们比较了小窝蛋白-1和-2的亚细胞分布、它们之间的相互作用以及它们在极化上皮细胞小窝形成中的作用。在表达低水平小窝蛋白-2且不表达小窝蛋白-1的Fischer大鼠甲状腺（FRT）细胞中，小窝蛋白-2仅定位于高尔基体复合物，但通过转染或腺病毒介导的转导共表达小窝蛋白-1后，它会部分重新分布到质膜。在组成性表达小窝蛋白-1和-2的Madin-Darby犬肾（MDCK）细胞中，小窝蛋白-2定位于高尔基体复合物和质膜，在质膜上它与小窝蛋白-1共同分布于扁平斑块和小窝中。在FRT细胞中，内源性或过表达的小窝蛋白-2不与在蔗糖密度梯度中漂浮的低密度Triton不溶性膜结合，但与小窝蛋白-1共表达时会被募集到这些膜上。在MDCK细胞中，小窝蛋白-1和小窝蛋白-2都与低密度Triton不溶性膜结合。在FRT细胞中，转染小窝蛋白-1促进了质膜小窝的组装，这些小窝优先（超过99%）定位于基底外侧表面，类似于MDCK细胞的组成性小窝。相反，正如从其细胞内分布所预期的那样，内源性或过表达的小窝蛋白-2不促进小窝的组装；相反，它似乎促进了高尔基体周围区域细胞内囊泡的组装。本文报道的数据表明，小窝蛋白-1和-2在极化上皮细胞中具有不同且互补的亚细胞定位和功能特性，并表明这两种蛋白质协同作用以在高尔基体复合物和细胞表面之间执行特定的未知任务。
