Palmitoylation regulates vesicular trafficking of R-Ras to membrane ruffles and effects on ruffling and cell spreading.
Palmitoylation regulates vesicular trafficking of R-Ras to membrane ruffles and effects on ruffling and cell spreading.
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DOI：
10.4161/sgtp.21084
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发表时间：
2012-07
期刊：
影响因子：
--
通讯作者：
Goldfinger LE
中科院分区：
文献类型：
--
作者：
Wurtzel JG;Kumar P;Goldfinger LE
在这项研究中，我们研究了R-Ras的细胞内运输的动力学及其对R-Ras在膜褶皱和细胞铺展中的独特作用的贡献。野生型和组成型活性R-Ras定位于Rab 11和转铁蛋白阳性和阴性囊泡的膜上，这些囊泡在迁移细胞中顺行地向前缘运输。H-Ras还与R-Ras在高尔基体附近的许多这些囊泡中共定位，但R-Ras和H-Ras囊泡以C-末端膜靶向序列决定的方式在前缘附近分离。这些分离的囊泡运输模式对应于在前缘靶向膜皱褶的不同模式。牛儿基牛儿基化是R-Ras的膜锚定所必需的，而棕榈酰化是从高尔基体后囊泡膜中离开并运输到质膜所必需的。R-Ras囊泡膜不含（3，4，5）-三磷酸磷脂酰肌醇（PtdIns（3，4，5）P3），而R-Ras与PtdIns（3，4，5）P3共定位于膜皱褶中。最后，棕榈酰化缺陷的R-Ras阻断膜皱褶、R-Ras/PI 3-激酶相互作用、PtdIns（3，4，5）P3在质膜上的富集以及R-Ras依赖的细胞铺展。因此，R-Ras的脂质修饰决定了其囊泡运输，靶向膜皱褶，以及其在将PtdIns（3，4，5）P3定位于皱褶和促进细胞铺展中的独特作用。
In this study we investigated the dynamics of R-Ras intracellular trafficking and its contributions to the unique roles of R-Ras in membrane ruffling and cell spreading. Wild type and constitutively active R-Ras localized to membranes of both Rab11- and transferrin-positive and -negative vesicles, which trafficked anterograde to the leading edge in migrating cells. H-Ras also co-localized with R-Ras in many of these vesicles in the vicinity of the Golgi, but R-Ras and H-Ras vesicles segregated proximal to the leading edge, in a manner dictated by the C-terminal membrane-targeting sequences. These segregated vesicle trafficking patterns corresponded to distinct modes of targeting to membrane ruffles at the leading edge. Geranylgeranylation was required for membrane anchorage of R-Ras, whereas palmitoylation was required for exit from the Golgi in post-Golgi vesicle membranes and trafficking to the plasma membrane. R-Ras vesicle membranes did not contain phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3), whereas R-Ras co-localized with PtdIns(3,4,5)P3 in membrane ruffles. Finally, palmitoylation-deficient R-Ras blocked membrane ruffling, R-Ras/PI3-kinase interaction, enrichment of PtdIns(3,4,5)P3 at the plasma membrane, and R-Ras-dependent cell spreading. Thus, lipid modification of R-Ras dictates its vesicle trafficking, targeting to membrane ruffles, and its unique roles in localizing PtdIns(3,4,5)P3 to ruffles and promoting cell spreading.