Rac homologues and compartmentalized phosphatidylinositol 4, 5-bisphosphate act in a common pathway to regulate polar pollen tube growth.
Rac homologues and compartmentalized phosphatidylinositol 4, 5-bisphosphate act in a common pathway to regulate polar pollen tube growth.
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DOI：
10.1083/jcb.145.2.317
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发表时间：
1999-04-19
影响因子：
7.8
通讯作者：
Chua, N H
中科院分区：
文献类型：
--
作者：
Kost, B;Lemichez, E;Spielhofer, P;Hong, Y;Tolias, K;Carpenter, C;Chua, N H
花粉管细胞的伸长依赖于顶端肌动蛋白的定向分泌. Rho家族小GTP酶参与动物和酵母细胞中相关过程的调节。我们的功能特点是Rac型Rho家族蛋白，在生长的花粉管中表达。显性负Rac的表达抑制花粉管伸长，而组成型活性Rac的表达诱导去极化生长。花粉管Rac被发现积累在顶端质膜和物理与磷脂酰肌醇单磷酸激酶（PtdIns P-K）的活动。PtdIns P-Ks的产物4，5-二磷酸磷脂酰肌醇（PtdIns 4，5-P2）与Rac具有相似的细胞内定位。与PtdIns 4，5-P2特异性结合的磷脂酶C（PLC）-δ1的pleckstrin同源（PH）结构域的表达抑制了花粉管的伸长。这些结果表明Rac和PtdIns 4，5-P2通过共同的途径控制极性花粉管的生长，并为PtdIns 4，5-P2在这一过程中的调控功能提供了直接证据。
Pollen tube cells elongate based on actin- dependent targeted secretion at the tip. Rho family small GTPases have been implicated in the regulation of related processes in animal and yeast cells. We have functionally characterized Rac type Rho family proteins that are expressed in growing pollen tubes. Expression of dominant negative Rac inhibited pollen tube elongation, whereas expression of constitutive active Rac induced depolarized growth. Pollen tube Rac was found to accumulate at the tip plasma membrane and to physically associate with a phosphatidylinositol monophosphate kinase (PtdIns P-K) activity. Phosphatidylinositol 4, 5-bisphosphate (PtdIns 4, 5-P2), the product of PtdIns P-Ks, showed a similar intracellular localization as Rac. Expression of the pleckstrin homology (PH)-domain of phospholipase C (PLC)-δ1, which binds specifically to PtdIns 4, 5-P2, inhibited pollen tube elongation. These results indicate that Rac and PtdIns 4, 5-P2 act in a common pathway to control polar pollen tube growth and provide direct evidence for a function of PtdIns 4, 5-P2 compartmentalization in the regulation of this process.