PDF(Pubmed)
Abstract：
The α-Aurora kinase is a crucial regulator of spindle microtubule organization during mitosis in plants. Here, we report a post-mitotic role for α-Aurora in reorganizing the phragmoplast microtubule array. In Arabidopsis thaliana, α-Aurora relocated from spindle poles to the phragmoplast midzone, where it interacted with the microtubule cross-linker MAP65-3. In a hypomorphic α-Aurora mutant, MAP65-3 was detected on spindle microtubules, followed by a diffuse association pattern across the phragmoplast midzone. Simultaneously, phragmoplast microtubules remained belatedly in a solid disk array before transitioning to a ring shape. Microtubules at the leading edge of the matured phragmoplast were often disengaged, accompanied by conspicuous retentions of MAP65-3 at the phragmoplast interior edge. Specifically, α-Aurora phosphorylated two residues towards the C-terminus of MAP65-3. Mutation of these residues to alanines resulted in an increased association of MAP65-3 with microtubules within the phragmoplast. Consequently, the expansion of the phragmoplast was notably slower compared to wild-type cells or cells expressing a phospho-mimetic variant of MAP65-3. Moreover, mimicking phosphorylation reinstated disrupted MAP65-3 behaviors in plants with compromised α-Aurora function. Overall, our findings reveal a mechanism in which α-Aurora facilitates cytokinesis progression through phosphorylation-dependent restriction of MAP65-3 associating with microtubules at the phragmoplast midzone.
摘要：
α-Aurora激酶是植物有丝分裂过程中纺锤体微管组织的关键调节剂。这里,我们报道了α-Aurora在重组原生质体微管阵列中的有丝分裂后作用。在拟南芥中，α-极光从纺锤体两极迁移到植骨中区，它与微管交联剂MAP65-3相互作用。在一个低态α-Aurora突变体中,在纺锤体微管上检测到MAP65-3，随后是整个植体中部区域的弥漫性关联模式。同时,原生质体微管在过渡到环形之前，已延迟保留在实心圆盘阵列中。成熟的原生质体前缘的微管经常脱离，伴有MAP65-3在原生质体内部边缘的明显保留。具体来说,α-Aurora磷酸化朝向MAP65-3的C末端的两个残基。这些残基突变为丙氨酸导致MAP65-3与原生质体内微管的结合增加。因此,与野生型细胞或表达MAP65-3的磷酸模拟变体的细胞相比,原生质体的扩增明显更慢。此外，在α-Aurora功能受损的植物中，模拟磷酸化恢复了MAP65-3行为的破坏。总的来说,我们的发现揭示了α-Aurora通过磷酸化依赖性限制MAP65-3与原生质体中区微管相关促进胞质分裂进程的机制.
