Table1_Functional specialization of Aurora kinase homologs during oogenic meiosis in the tunicate Oikopleura dioica.DOCX

A single Aurora kinase found in non-vertebrate deuterostomes is assumed to represent the ancestor of vertebrate Auroras A/B/C. However, the tunicate Oikopleura dioica, a member of the sister group to vertebrates, possesses two Aurora kinases (Aurora1 and Aurora2) that are expressed in proliferative cells and reproductive organs. Previously, we have shown that Aurora kinases relocate from organizing centers to meiotic nuclei and were enriched on centromeric regions as meiosis proceeds to metaphase I. Here, we assessed their respective functions in oogenic meiosis using dsRNA interferences. We found that Aurora1 (Aur1) was involved in meiotic spindle organization and chromosome congression, probably through the regulation of microtubule dynamics, whereas Aurora2 (Aur2) was crucial for chromosome condensation and meiotic spindle assembly. In vitro kinase assays showed that Aur1 and Aur2 had comparable levels of kinase activities. Using yeast two-hybrid library screening, we identified a few novel interaction proteins for Aur1, including c-Jun-amino-terminal kinase-interacting protein 4, cohesin loader Scc2, and mitochondrial carrier homolog 2, suggesting that Aur1 may have an altered interaction network and participate in the regulation of microtubule motors and cohesin complexes in O. dioica.

在非脊椎动物中的棘皮动物门中发现的单一 Aurora 激酶被认为代表了脊椎动物 Aurora A/B/C 的祖先。然而，作为脊椎动物姐妹群的苔藓动物 Oikopleura dioica 拥有两种 Aurora 激酶（Aurora1 和 Aurora2），这两种激酶在增殖细胞和生殖器官中表达。先前研究表明，Aurora 激酶从组织中心重新定位至减数分裂核，并在减数分裂进行至减数第一次分裂中期时富集于着丝粒区域。在本研究中，我们利用 dsRNA 干扰技术评估了它们在卵原性减数分裂中的各自功能。我们发现 Aurora1（Aur1）参与了减数纺锤体的组织化和染色体收敛，可能通过调控微管动态来实现，而 Aurora2（Aur2）对于染色体凝聚和减数纺锤体组装至关重要。体外激酶活性测定显示，Aur1 和 Aur2 的激酶活性水平相当。通过酵母双杂交库筛选，我们鉴定出几个与 Aur1 相互作用的蛋白质，包括 c-Jun 氨基末端激酶相互作用蛋白 4、着丝粒连接蛋白 Scc2 和线粒体载体同源蛋白 2，这表明 Aur1 可能具有改变的相互作用网络，并在 O. dioica 中参与微管马达和着丝粒复合物的调控。