Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
Biol Open. 2014 Jun 6;3(7):561-70. doi: 10.1242/bio.20148276.
Kinesin-13 motors are unusual in that they do not walk along microtubules, but instead diffuse to the ends, where they remove tubulin dimers, regulating microtubule dynamics. Here we show that Drosophila kinesin-13 klp10A regulates oocyte meiosis I spindle length and is haplo-insufficient - KLP10A, reduced by RNAi or a loss-of-function P element insertion mutant, results in elongated and mispositioned oocyte spindles, and abnormal cortical microtubule asters and aggregates. KLP10A knockdown by RNAi does not significantly affect microtubule growth rates in oocyte spindles, but, unexpectedly, EB1 binding and unbinding are slowed, suggesting a previously unobserved role for kinesin-13 in mediating EB1 binding interactions with microtubules. Kinesin-13 may regulate spindle length both by disassembling subunits from microtubule ends and facilitating EB1 binding to plus ends. We also observe an increased number of paused microtubules in klp10A RNAi knockdown spindles, consistent with a reduced frequency of microtubule catastrophes. Overall, our findings indicate that reduced kinesin-13 decreases microtubule disassembly rates and affects EB1 interactions with microtubules, rather than altering microtubule growth rates, causing spindles to elongate and abnormal cortical microtubule asters and aggregates to form.
驱动蛋白-13 马达的独特之处在于它们不会沿着微管运动，而是扩散到微管的末端，在那里它们去除微管二聚体，从而调节微管动力学。在这里，我们表明果蝇驱动蛋白-13 klp10A 调节卵母细胞减数分裂 I 纺锤体的长度，并且是杂合不足的 - 通过 RNAi 或功能丧失 P 元件插入突变体减少 KLP10A，导致卵母细胞纺锤体拉长和位置不正，以及异常的皮质微管星状体和聚集体。通过 RNAi 敲低 KLP10A 不会显著影响卵母细胞纺锤体中微管的生长速率，但出人意料的是，EB1 的结合和解离速度减慢，这表明驱动蛋白-13 在介导 EB1 与微管的结合相互作用中具有以前未观察到的作用。驱动蛋白-13 可能通过从微管末端解聚亚基并促进 EB1 与正极的结合来调节纺锤体的长度。我们还观察到在 klp10A RNAi 敲低纺锤体中，暂停的微管数量增加，这与微管灾难的频率降低一致。总的来说，我们的发现表明，减少驱动蛋白-13 会降低微管解聚的速度，并影响 EB1 与微管的相互作用，而不是改变微管的生长速度，导致纺锤体伸长和异常的皮质微管星状体和聚集体形成。
