Yeast lacking the amphiphysin family protein Rvs167 is sensitive to disruptions in sphingolipid levels
Yeast lacking the amphiphysin family protein Rvs167 is sensitive to disruptions in sphingolipid levels
复制标题
缺乏两性蛋白家族蛋白 Rvs167 的酵母对鞘脂水平的破坏敏感
作者：
Toume M;and Tani M
酵母中的Rvs 167和Rvs 161是两个两栖蛋白家族，参与细胞内吞囊泡的内陷和破裂以及肌动蛋白细胞骨架的组装等重要的细胞事件。据报道，由RVS 167或RVS 161缺失引起的细胞功能障碍可通过缺失特定的非必需鞘脂代谢酶基因来挽救。在这里，我们发现缺少RVS 167或RVS 161的酵母细胞表现出鞘脂水平的降低。在rvs 167 cells中，Orm 2的表达水平以钙调神经磷酸酶依赖性方式增加，Orm 2是丝氨酸棕榈酰转移酶（SPT）催化鞘脂生物合成初始步骤的负调控因子，而rvs 167 cells中鞘脂水平的降低在缺失ORM 2时逆转。此外，ORM 1和ORM 2表达的抑制或SPT的过表达引起rvs 167 p53细胞的强烈生长缺陷，表明去Novosphingolipid生物合成的增强对rvs 167 p53细胞是不利的。相反，部分抑制LCB 1编码SPT抑制了由RVS 167缺失引起的异常表型，包括对高温和盐胁迫的超敏感性，以及内吞作用和肌动蛋白细胞骨架组织的损害。此外，SPT活性的部分抑制抑制了温度超敏感性和由编码发动蛋白样GT α的VPS 1缺失引起的异常空泡形态，该GT3是囊泡断裂所需的，并且在功能上与Rvs 167/Rvs 161密切相关，而抑制ORM 1和ORM 2表达则导致了VPS 167细胞的生长缺陷。因此，有人建议，适当的调节SPT活性是必不可少的两栖激素缺陷的细胞。
Rvs167 and Rvs161 inSaccharomyces cerevisiaeare amphiphysin family proteins, which are involved in several important cellular events, such as invagination and scission of endocytic vesicles, and actin cytoskeleton organization. It has been reported that cellular dysfunctions caused by deletion ofRVS167orRVS161are rescued by deletion of specific nonessential sphingolipid‐metabolizing enzyme genes. Here, we found that yeast cells lackingRVS167orRVS161exhibit a decrease in sphingolipid levels. Inrvs167∆cells, the expression level of Orm2, a negative regulator of serine palmitoyltransferase (SPT) catalyzing the initial step of sphingolipid biosynthesis, was increased in a calcineurin‐dependent manner, and the decrease in sphingolipid levels inrvs167∆cells was reversed on deletion ofORM2. Moreover, repression of bothORM1andORM2expression or overexpression of SPT caused a strong growth defect ofrvs167∆cells, indicating that enhancement ofde novosphingolipid biosynthesis is detrimental torvs167∆cells. In contrast, partial repression ofLCB1‐encoding SPT suppressed abnormal phenotypes caused by the deletion ofRVS167, including supersensitivity to high temperature and salt stress, and impairment of endocytosis and actin cytoskeleton organization. In addition, the partial repression of SPT activity suppressed the temperature supersensitivity and abnormal vacuolar morphology caused by deletion ofVPS1encoding a dynamin‐like GTPase, which is required for vesicle scission and is functionally closely related to Rvs167/Rvs161, whereas repression of bothORM1andORM2expression invps1∆cells caused a growth defect. Thus, it was suggested that proper regulation of SPT activity is indispensable for amphiphysin‐deficient cells.