Baluska F, von Witsch M, Peters M, Hlavacka A, Volkmann D
Botanisches Institut, Rheinische Friedrich-Wilhelms-Universität Bonn, Department of Plant Cell Biology, Kirschallee 1, D-53115 Bonn, Germany.
Plant Cell Physiol. 2001 Sep;42(9):912-22. doi: 10.1093/pcp/pce116.
Indirect immunofluorescence localization of profilin in cells of maize root apices revealed that this abundant protein was present both in the cytoplasm and within nuclei. Nucleo-cytoplasmic partitioning of profilin exhibits tissue-specific and developmental features. Mastoparan-mediated activation of heterotrimeric G-proteins, presumably through triggering a phosphoinositide-signaling pathway based on phosphatidylinositol-4,5-bisphosphate (PIP(2)), induced relocalization of profilin from nuclei into the cytoplasm of root apex cells. In contrast, PIP(2) accumulated within nuclei of mastoparan-treated root cells. Intriguingly, cytoplasmic accumulation of profilin was associated with remodeling of F-actin arrays in root apex cells. Specifically, dense F-actin networks were dismantled and distinct actin patches became associated with the periphery of small vacuoles. On the other hand, disruption of F-actin with the G-actin sequestering agent latrunculin B does not affect the subcellular distribution of profilin or PIP(2). These data suggest that nuclear profilin can mediate a stimulus-response action on the actin cytoskeleton which is somehow linked to a phosphoinositide-signaling cascade.
对玉米根尖细胞中肌动蛋白结合蛋白进行间接免疫荧光定位显示，这种丰富的蛋白质存在于细胞质和细胞核中。肌动蛋白结合蛋白的核质分配具有组织特异性和发育特征。推测mastoparan通过基于磷脂酰肌醇 - 4,5 - 二磷酸（PIP(2)）触发磷酸肌醇信号通路来激活异源三聚体G蛋白，从而诱导肌动蛋白结合蛋白从细胞核重新定位到根尖细胞的细胞质中。相反，PIP(2)在经mastoparan处理的根细胞的细胞核中积累。有趣的是，肌动蛋白结合蛋白在细胞质中的积累与根尖细胞中F - 肌动蛋白阵列的重塑有关。具体而言，密集的F - 肌动蛋白网络被拆解，不同的肌动蛋白斑与小液泡的周边相关联。另一方面，用G - 肌动蛋白螯合剂Latrunculin B破坏F - 肌动蛋白并不影响肌动蛋白结合蛋白或PIP(2)的亚细胞分布。这些数据表明，核肌动蛋白结合蛋白可以介导对肌动蛋白细胞骨架的刺激反应作用，这在某种程度上与磷酸肌醇信号级联相关。
