Disturbance of sphingolipid biosynthesis abrogates the signaling of Mss4, phosphatidylinositol-4-phosphate 5-kinase, in yeast
Disturbance of sphingolipid biosynthesis abrogates the signaling of Mss4, phosphatidylinositol-4-phosphate 5-kinase, in yeast
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DOI：
10.1074/jbc.m414138200
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发表时间：
2005-05-06
影响因子：
4.8
通讯作者：
Kozutsumi, Y
中科院分区：
文献类型：
--
作者：
Kobayashi, T;Takematsu, H;Kozutsumi, Y
磷酸肌苷和鞘脂之间的功能关系至今尚未得到很好的表征。ISP-1/肉豆蔻素是一种有效的鞘脂生物合成抑制剂，可引起真核细胞因鞘脂剥夺而产生严重的生长缺陷。我们在酵母中发现了一种新的多拷贝抑制isp -1介导的细胞死亡的基因MSS4。MSS4编码一个磷脂酰肌醇-4-磷酸5激酶，该激酶可合成磷脂酰肌醇(4,5)-二磷酸（pi4,5p(2)）。我们在这里证明了ISP-1处理酵母会导致Mss4活性和亚细胞定位的缺陷。我们研究了Mss4缺陷对下游信号传导的影响，因为Mss4产物、PI4、5P2和Rom2的pleckstrin同源结构域之间的相互作用介导了Rom2向膜的募集，这是随后Rho1/2激活的关键步骤。事实上，在isp -1处理的细胞和csg2缺失的细胞中观察到Rom2募集失败，这减少了甘露糖化肌醇磷酸化神经酰胺。这些数据表明，涉及Mss4的信号通路需要适当的鞘脂。
The functional relationships between phosphoinositides and sphingolipids have not been well characterized to date. ISP-1/myriocin is a potent inhibitor of sphingolipid biosynthesis and induces severe growth defects in eukaryotic cells because of the sphingolipid deprivation. We characterized a novel multicopy suppressor gene of ISP-1-mediated cell death in yeast, MSS4. MSS4 encodes a phosphatidylinositol-4-phosphate5-kinase that synthesizes phosphatidylinositol ( 4,5)-bisphosphate (PI4,5P(2)). We demonstrate here that ISP-1 treatment of yeast causes defects both in the activity and subcellular localization of Mss4. The effect of the Mss4 defect on the downstream signaling was examined, because interaction between the Mss4 product, PI4,5P2, and the pleckstrin-homology domain of Rom2 mediates recruitment of Rom2 to the membrane, which is the crucial step for subsequent Rho1/2 activation. Indeed, failure of Rom2 recruitment was observed in ISP-1-treated cells as well as in csg2-deleted cells, which have reduced mannosylated inositolphosphorylceramide. These data suggested that proper sphingolipids are required for the signaling pathway involving Mss4.