Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan.
Plant Signal Behav. 2011 May;6(5):743-7. doi: 10.4161/psb.6.5.15146. Epub 2011 May 1.
Plant cytokinesis occurs by the growth of cell plates from the interior to the periphery of the cell. These dynamic events in cytokinesis are mediated by a plant-specific microtubule (MT) array called the phragmoplast, which consists of bundled antiparallel MTs between the two daughter nuclei. The NACK-PQR pathway, a NACK1 kinesin-like protein and mitogen activated protein kinase (MAPK) cascade, is a key regulator of plant cytokinesis through the regulation of phragmoplast MTs. The MT-associated protein MAP65 has been identified as one of the structural components of MT assays involved in cell division, and we recently showed that Arabidopsis AtMAP65-3/PLEIADE (PLE) is a substrate of MPK4 that is a component of the NACK-PQR pathway in Arabidopsis. Here we show that AtMAP65-1 and AtMAP65-2 are also phosphorylated by MPK4. AtMAP65-1 and AtMAP65-2 that localize to the phragmoplast were phosphorylated by MPK4 in vitro. Although mutants of the Arabidopsis AtMAP65-1 and AtMAP65-2 genes exhibited a wild-type phenotype, double mutations of AtMAP65-3 and AtMAP65-1 or AtMAP65-2 caused more severe growth and cytokinetic defects than the single atmap65-3/ple mutation. These results suggest that AtMAP65-1 and AtMAP65-2 also function in cytokinesis downstream of MPK4.
植物细胞的胞质分裂是通过细胞板从细胞内部向细胞外周生长来实现的。这些胞质分裂过程中的动态事件是由一种称为成膜体的植物特异性微管（MT）阵列介导的，它由两个子核之间的束状平行 MT 组成。NACK-PQR 途径，一种 NACK1 类驱动蛋白和丝裂原活化蛋白激酶（MAPK）级联，是通过调节成膜体 MT 来调节植物胞质分裂的关键调节剂。MT 相关蛋白 MAP65 已被鉴定为参与细胞分裂的 MT 检测的结构成分之一，我们最近表明，拟南芥 AtMAP65-3/PLEIADE（PLE）是 NACK-PQR 途径中 MAPK4 的一个底物。在这里，我们表明 AtMAP65-1 和 AtMAP65-2 也被 MPK4 磷酸化。在体外，定位于成膜体的 AtMAP65-1 和 AtMAP65-2 被 MPK4 磷酸化。尽管拟南芥 AtMAP65-1 和 AtMAP65-2 基因的突变体表现出野生型表型，但 AtMAP65-3 和 AtMAP65-1 或 AtMAP65-2 的双突变导致比单个 atmap65-3/ple 突变更严重的生长和胞质分裂缺陷。这些结果表明 AtMAP65-1 和 AtMAP65-2 也在 MPK4 下游的胞质分裂中发挥作用。
