The Arabidopsis phosphatidylinositol phosphate 5-kinase PIP5K3 is a key regulator of root hair tip growth
The Arabidopsis phosphatidylinositol phosphate 5-kinase PIP5K3 is a key regulator of root hair tip growth
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DOI：
10.1105/tpc.107.056119
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发表时间：
2008-02-01
期刊：
影响因子：
11.6
通讯作者：
Aoyama, Takashi
中科院分区：
文献类型：
--
作者：
Kusano, Hiroaki;Testerink, Christa;Aoyama, Takashi
磷脂酰肌醇4，5-二磷酸[PtdIns（4，5）P-2]作为膜上的位点特异性信号，促进细胞骨架重组和膜运输。PtdIns（4，5）P2定位于生长的根毛和花粉管的顶端，表明它在根尖生长中起重要作用。然而，其监管和行动方式仍不清楚。我们发现，拟南芥PIP 5 K3（磷脂酰肌醇磷酸5-激酶3）编码磷脂酰肌醇4-磷酸5-激酶，一个关键酶产生PtdIns（4，5）P2，这是优先在生长的根毛中表达。T-DNA插入突变，大大减少了PIP 5 K3的表达，导致显着较短的根毛比野生型。相比之下，过度表达导致更长的根毛和多个突出的网站上一个单一的毛细胞。由PIP 5 K3启动子驱动的PIP 5 K3的黄色荧光蛋白（YFP）融合物补充了短根毛表型。PIP 5 K3-YFP定位于伸长的根毛顶端的质膜和细胞质空间，生长的根毛凸起，并且，值得注意的是，定位于将要形成根毛凸起的位点。信号在快速生长的根毛中最大，当伸长停止时迅速消失。这些结果提供了PIP 5 K3参与将PtdIns（4，5）P2定位到伸长的根毛顶端的证据，并且是启动和促进根毛顶端生长的机制的关键调节剂。
Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5) P-2] functions as a site-specific signal on membranes to promote cytoskeletal reorganization and membrane trafficking. Localization of PtdIns(4,5) P2 to apices of growing root hairs and pollen tubes suggests that it plays an important role in tip growth. However, its regulation and mode of action remain unclear. We found that Arabidopsis thaliana PIP5K3 (for Phosphatidylinositol Phosphate 5-Kinase 3) encodes a phosphatidylinositol 4-phosphate 5-kinase, a key enzyme producing PtdIns(4,5) P2, that is preferentially expressed in growing root hairs. T-DNA insertion mutations that substantially reduced the expression of PIP5K3 caused significantly shorter root hairs than in the wild type. By contrast, overexpression caused longer root hairs and multiple protruding sites on a single trichoblast. A yellow fluorescent protein (YFP) fusion of PIP5K3, driven by the PIP5K3 promoter, complemented the short-root-hair phenotype. PIP5K3-YFP localized to the plasma membrane and cytoplasmic space of elongating root hair apices, to growing root hair bulges, and, notably, to sites about to form root hair bulges. The signal was greatest in rapidly growing root hairs and quickly disappeared when elongation ceased. These results provide evidence that PIP5K3 is involved in localizing PtdIns(4,5) P2 to the elongating root hair apex and is a key regulator of the machinery that initiates and promotes root hair tip growth.