Study on Neutral Ceramidase involved in Sphingolipid Signaling

中性神经酰胺酶参与鞘脂信号传导的研究

基本信息

批准号：
17380068
负责人：
ITO Makoto
金额：
$ 9.41万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

Neutral ceramidases (CDases) are widely distributed from bacteria to humans. The bacteria and drosophila enzymes are exclusively secretory while the zebrafish and mammalian enzymes are typical type II integral membrane proteins which occasionally detach from cells after the processing of their NH2-terminal anchor. We found that the difference in the localization of the enzyme is entirely due to the presence of a mucin-like domain located downstream of the NH2-terminal signal/anchor sequence of the enzymes from vertebrates but not bacteria and invertebrates. Overexpression of mouse neutral CDase on the cell-surface or in the extracellular milieu but not in the ER significantly increased the intracellular concentration of sphingosine as well as sphingosine 1-phosphate (SIP) when the amount of cell-surface ceramide was increased by treatment of cells with bacterial sphingomyelinase. In contrast, knockdown of the CDase reduced the amount of both sphingolipid metabolites. The enzyme seems to participate in the generation of S1P in the vascular system in which cell-and lipoprotein-bound sphingomyelin are likely to be a source of ceramide. The knockdown of the neutral CDase impaired both S1P-mediated angiogenesis and the development of the heart during zebrafish embryogenesis, leading a lack of circulation of blood cells. Collectively, the enzyme is involved in the metabolism of ceramide at the plasma membranes and in the extracellular milieu, which could regulate the generation of SIP and S1P-mediated signaling through the production of sphingosine.

中性神经酰胺酶（CDases）广泛从细菌到人分布。细菌和果蝇酶是独家分泌的，而斑马鱼和哺乳动物酶是典型的II型积分膜蛋白，在其NH2-末端锚固后，有时会从细胞中脱离细胞。我们发现，酶的定位差异完全是由于存在位于脊椎动物的酶的NH2-末端信号/锚定序列下游的粘蛋白样结构域的存在，但不是细菌和无脊椎动物。小鼠中性CDase在细胞表面或细胞外环境中的过表达，而在ER中没有显着增加鞘氨醇内细胞内浓度以及1-磷酸鞘氨醇（SIP），当细胞表皮神经酰胺的量通过用细菌鞘氨细胞瘤瘤瘤瘤菌骨酶处理而增加。相反，CDase的敲低减少了两种鞘脂代谢物的量。该酶似乎参与了血管系统中S1P的产生，其中细胞和脂蛋白结合的鞘磷脂可能是神经酰胺的来源。中性CDase的敲低损害了S1P介导的血管生成和斑马鱼胚胎发生过程中心脏的发育，导致缺乏血细胞的循环。总体而言，该酶参与了质膜和细胞外环境中神经酰胺的代谢，该酶可以通过生产鞘氨酸的产生来调节SIP和S1P介导的信号传导的产生。