F-actin-dependent endocytosis of cell wall pectins in meristematic root cells. Insights from brefeldin A-induced compartments
F-actin-dependent endocytosis of cell wall pectins in meristematic root cells. Insights from brefeldin A-induced compartments
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DOI：
10.1104/pp.007526
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发表时间：
2002-09-01
期刊：
影响因子：
7.4
通讯作者：
Volkmann, D
中科院分区：
文献类型：
--
作者：
Baluska, F;Hlavacka, A;Volkmann, D
Brefeldin A(BFA)抑制胞吐作用，但允许内吞作用，使其成为识别在细胞外围循环的分子的有价值的试剂。在植物中，对BFA处理的反应形成大的细胞内隔室是一些但不是所有细胞的独特特征。在这里，我们分析了BFA区段在生长玉米(Zea Mays)根尖的发育和组织特异性环境中的组装和分布。令人惊讶的是，这些独特的隔室只在根体的分生组织细胞中形成。另一方面，根冠外围的分泌细胞、次生木质部细胞和大多数伸长细胞都没有BFA隔室，这些细胞都活跃在胞吐作用中。我们报道了计算鼠李半乳糖醛酸二聚体11个二聚体的果胶表位被部分酯化(高达40%)的高半乳糖醛酸果胶和鼠李半乳糖醛酸I的(1--和4)-β-D-半乳糖侧链内化到BFA隔室中。相比之下，高尔基体分泌的(酯化高达80%)高半乳糖醛酸果胶定位于对照细胞的细胞质中，而不在特定的BFA间隔内积累。Latrunculin B介导的F-肌动蛋白解聚抑制了细胞壁果胶在细胞内BFA隔室内的内化和积累。重要的是，冷处理和原生质体在BFA处理时阻止了壁果胶内化到根细胞中。这些观察结果表明，分生组织玉米根细胞的细胞壁果胶以F-肌动蛋白依赖的方式进行快速内吞。
Brefeldin A (BFA) inhibits exocytosis but allows endocytosis, making it a valuable agent to identify molecules that recycle at cell peripheries. In plants, formation of large intracellular compartments in response to BFA treatment is a unique feature of some, but not all, cells. Here, we have analyzed assembly and distribution of BFA compartments in development- and tissue-specific contexts of growing maize (Zea mays) root apices. Surprisingly, these unique compartments formed only in meristematic cells of the root body. On the other hand, BFA compartments were absent from secretory cells of root cap periphery, metaxylem cells, and most elongating cells, all of which are active in exocytosis. We report that cell wall pectin epitopes counting rhamnogalacturonan 11 dimers cross-linked by borate diol diester, partially esterified (up to 40%) homogalacturonan pectins, and (1-->4)-beta-D-galactan side chains of rhamnogalacturonan I were internalized into BFA compartments. In contrast, Golgi-derived secretory (esterified up to 80%) homogalacturonan pectins localized to the cytoplasm in control cells and did not accumulate within characteristic BFA compartments. Latrunculin B-mediated depolymerization of F-actin inhibited internalization and accumulation of cell wall pectins within intracellular BFA compartments. Importantly, cold treatment and protoplasting prevented internalization of wall pectins into root cells upon BFA treatment. These observations Suggest that cell wall pectins of meristematic maize root cells undergo rapid endocytosis in an F-actin-dependent manner.