Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, U-4225 Medical Research Building III, 465 21st Avenue South, Nashville, TN 37232-8240, USA.
Development. 2012 Aug;139(16):2945-54. doi: 10.1242/dev.077511. Epub 2012 Jul 4.
Dynein, a microtubule motor complex, plays crucial roles in cell-cycle progression in many systems. The LIS1 accessory protein directly binds dynein, although its precise role in regulating dynein remains unclear. Mutation of human LIS1 causes lissencephaly, a developmental brain disorder. To gain insight into the in vivo functions of LIS1, we characterized a male-sterile allele of the Drosophila homolog of human LIS1. We found that centrosomes do not properly detach from the cell cortex at the onset of meiosis in most Lis-1 spermatocytes; centrosomes that do break cortical associations fail to attach to the nucleus. In Lis-1 spermatids, we observed loss of attachments between the nucleus, basal body and mitochondria. The localization pattern of LIS-1 protein throughout Drosophila spermatogenesis mirrors that of dynein. We show that dynein recruitment to the nuclear surface and spindle poles is severely reduced in Lis-1 male germ cells. We propose that Lis-1 spermatogenesis phenotypes are due to loss of dynein regulation, as we observed similar phenotypes in flies null for Tctex-1, a dynein light chain. We have previously identified asunder (asun) as another regulator of dynein localization and centrosome positioning during Drosophila spermatogenesis. We now report that Lis-1 is a strong dominant enhancer of asun and that localization of LIS-1 in male germ cells is ASUN dependent. We found that Drosophila LIS-1 and ASUN colocalize and coimmunoprecipitate from transfected cells, suggesting that they function within a common complex. We present a model in which Lis-1 and asun cooperate to regulate dynein localization and centrosome positioning during Drosophila spermatogenesis.
动力蛋白是一种微管马达复合物，在许多系统的细胞周期进程中发挥着关键作用。LIS1 辅助蛋白直接与动力蛋白结合，尽管其在调节动力蛋白方面的确切作用尚不清楚。人类 LIS1 的突变导致无脑回畸形，这是一种发育性脑疾病。为了深入了解 LIS1 的体内功能，我们对果蝇同源物的一个雄性不育等位基因进行了特征描述。我们发现，在大多数 Lis-1 精母细胞中，中心体在减数分裂开始时不能从细胞皮层正确分离；分离皮质联系的中心体不能附着到核上。在 Lis-1 精细胞中，我们观察到核、基底体和线粒体之间的连接丧失。LIS1 蛋白在整个果蝇精子发生过程中的定位模式与动力蛋白相似。我们表明，在 Lis-1 雄性生殖细胞中，动力蛋白向核表面和纺锤极的募集严重减少。我们提出，Lis-1 精子发生表型是由于动力蛋白调节丧失所致，因为我们在 Tctex-1 缺失的果蝇中观察到了类似的表型，Tctex-1 是一种动力蛋白轻链。我们之前已经确定了 asunder (asun) 是另一种调节果蝇精子发生过程中动力蛋白定位和中心体定位的调节剂。我们现在报告说，Lis-1 是 asun 的一个强显性增强子，并且 LIS-1 在雄性生殖细胞中的定位是 ASUN 依赖性的。我们发现果蝇 LIS-1 和 ASUN 从转染细胞中共定位并共免疫沉淀，表明它们在一个共同的复合物中发挥作用。我们提出了一个模型，即 Lis-1 和 asun 合作调节果蝇精子发生过程中的动力蛋白定位和中心体定位。
