Exocytosis is a process by which vesicles are transported to and fused with specific areas of the plasma membrane. Although several studies have shown that sphingolipids are the main components of exocytic compartments, whether they control exocytosis process is unclear. Here, we have investigated the role of sphingolipids in exocytosis by reducing the activity of the serine palmitoyl-transferase (SPT), which catalyzes the first step in sphingolipid synthesis in endoplasmic reticulum. We found that the exocyst polarity and exocytic secretion were impaired in lcb1-100 mutant cells and in wild type cells treated with myriocin, a chemical which can specifically inhibit SPT enzyme activity, suggesting that sphingolipids controls exocytic secretion. This speculation was further confirmed by immuno-fluorescence and electron microscopy results that small secretory vesicles were accumulated in lcb1-100 mutant cells. Taken together, our results suggest that sphingolipids are required for exocytosis. Mammals may use similar regulatory mechanisms because components of the exocytic secretion apparatus and signaling pathways are conserved.

中文翻译：

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鞘脂是酿酒酵母胞外囊极性和胞外分泌所必需的

胞吐作用是囊泡被转运到质膜特定区域并与其融合的过程。尽管多项研究表明鞘脂是胞吐区室的主要成分，但它们是否控制胞吐过程尚不清楚。在这里，我们通过降低丝氨酸棕榈酰转移酶 (SPT) 的活性来研究鞘脂在胞吐作用中的作用，该酶催化内质网中鞘脂合成的第一步。我们发现，在 lcb1-100 突变细胞和用 myriocin（一种可以特异性抑制 SPT 酶活性的化学物质）处理的野生型细胞中，胞外囊的极性和胞外分泌受损，这表明鞘脂控制胞外分泌。免疫荧光和电子显微镜结果进一步证实了这一推测，即在 lcb1-100 突变细胞中积累了小的分泌囊泡。总之，我们的结果表明鞘脂是胞吐作用所必需的。哺乳动物可能使用类似的调节机制，因为胞外分泌装置和信号通路的成分是保守的。