Pheromone-induced anisotropy in yeast plasma membrane phosphatidylinositol-4,5-bisphosphate distribution is required for MAPK signaling
Pheromone-induced anisotropy in yeast plasma membrane phosphatidylinositol-4,5-bisphosphate distribution is required for MAPK signaling
复制标题
DOI：
10.1073/pnas.1005817107
复制
发表时间：
2010-06-29
影响因子：
11.1
通讯作者：
Thorner, Jeremy
中科院分区：
文献类型：
--
作者：
Garrenton, Lindsay S.;Stefan, Christopher J.;Thorner, Jeremy
在芽殖酵母肽交配信息素的反应，细胞变得显着极化和MAPK支架蛋白Ste 5定位到所产生的投影（shmoo提示）。我们之前证明了这种募集对于持续的MAPK信号传导是必不可少的，并且需要Ste 5中的普列克底物蛋白同源（PH）结构域与质膜中的磷脂酰肌醇4，5-二磷酸[PtdIns（4，5）P-2]的相互作用。使用荧光标记的高亲和力探针特异性PtdIns（4，5）P-2，我们现在已经发现，这种磷酸肌醇是高度集中在shmoo尖端的细胞响应信息素。PtdIns（4，5）P-2的这种显著各向异性分布的维持、Ste 5在shmoo尖端的稳定束缚、下游MAPK活化和交配途径特异性报告基因的表达都需要质膜相关PtdIns 4-激酶Stt 4和质膜相关PtdIns 4P 5-激酶Mss 4（但不是高尔基体相关PtdIns 4-激酶Pik 1）的连续功能。我们的观察结果表明，PtdIns（4，5）P-2是限制定位在质膜内的Ste 5的主要决定因素，并提供了直接的证据表明，细胞外刺激诱发的自我增强机制产生了一个空间富集的PtdIns（4，5）P-2的膜锚定和信号复合物的功能所必需的池。
During response of budding yeast to peptide mating pheromone, the cell becomes markedly polarized and MAPK scaffold protein Ste5 localizes to the resulting projection (shmoo tip). We demonstrated before that this recruitment is essential for sustained MAPK signaling and requires interaction of a pleckstrin homology (PH) domain in Ste5 with phosphatidylinositol 4,5-bisphosphate [PtdIns (4,5)P-2] in the plasma membrane. Using fluorescently tagged high-affinity probes specific for PtdIns(4,5)P-2, we have now found that this phosphoinositide is highly concentrated at the shmoo tip in cells responding to pheromone. Maintenance of this strikingly anisotropic distribution of PtdIns(4,5)P-2, stable tethering of Ste5 at the shmoo tip, downstream MAPK activation, and expression of a mating pathway-specific reporter gene all require continuous function of the plasma membrane-associated PtdIns 4-kinase Stt4 and the plasma membrane-associated PtdIns4P 5-kinase Mss4 (but not the Golgi-associated PtdIns 4-kinase Pik1). Our observations demonstrate that PtdIns(4,5)P-2 is the primary determinant for restricting localization of Ste5 within the plasma membrane and provide direct evidence that an extracellular stimulus-evoked self-reinforcing mechanism generates a spatially enriched pool of PtdIns (4,5)P-2 necessary for the membrane anchoring and function of a signaling complex.