Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232-8240, USA.
Mol Biol Cell. 2012 Dec;23(24):4713-24. doi: 10.1091/mbc.E12-07-0558. Epub 2012 Oct 24.
Recruitment of dynein motors to the nuclear surface is an essential step for nucleus-centrosome coupling in prophase. In cultured human cells, this dynein pool is anchored to nuclear pore complexes through RanBP2-Bicaudal D2 (BICD2) and Nup133- centromere protein F (CENP-F) networks. We previously reported that the asunder (asun) gene is required in Drosophila spermatocytes for perinuclear dynein localization and nucleus-centrosome coupling at G2/M of male meiosis. We show here that male germline expression of mammalian Asunder (ASUN) protein rescues asun flies, demonstrating evolutionary conservation of function. In cultured human cells, we find that ASUN down-regulation causes reduction of perinuclear dynein in prophase of mitosis. Additional defects after loss of ASUN include nucleus-centrosome uncoupling, abnormal spindles, and multinucleation. Coimmunoprecipitation and overlapping localization patterns of ASUN and lissencephaly 1 (LIS1), a dynein adaptor, suggest that ASUN interacts with dynein in the cytoplasm via LIS1. Our data indicate that ASUN controls dynein localization via a mechanism distinct from that of either BICD2 or CENP-F. We present a model in which ASUN promotes perinuclear enrichment of dynein at G2/M that facilitates BICD2- and CENP-F-mediated anchoring of dynein to nuclear pore complexes.
动力蛋白向核表面的募集是核-中心体在前期偶联的一个必要步骤。在培养的人细胞中，这个动力蛋白池通过 RanBP2-Bicaudal D2（BICD2）和 Nup133-着丝粒蛋白 F（CENP-F）网络锚定在核孔复合物上。我们之前的研究表明，asunder（asun）基因在果蝇精母细胞中对于核周动力蛋白的定位和 G2/M 期雄性减数分裂的核-中心体偶联是必需的。我们在这里表明，哺乳动物 Asunder（ASUN）蛋白在雄性生殖系中的表达可以拯救 asun 果蝇，证明了功能的进化保守性。在培养的人细胞中，我们发现 ASUN 的下调导致有丝分裂前期核周动力蛋白减少。ASUN 缺失后的其他缺陷包括核-中心体解偶联、异常纺锤体和多核化。ASUN 和 Lissencephaly 1（LIS1）（一种动力蛋白接头）的共免疫沉淀和重叠定位模式表明，ASUN 通过 LIS1 在细胞质中与动力蛋白相互作用。我们的数据表明，ASUN 通过一种与 BICD2 或 CENP-F 不同的机制来控制动力蛋白的定位。我们提出了一个模型，其中 ASUN 促进了 G2/M 期核周动力蛋白的富集，从而促进了 BICD2 和 CENP-F 介导的动力蛋白与核孔复合物的锚定。
