Experimental Parasitology, Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität, LMU, Munich, 82152, Planegg, Germany.
Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität, LMU, Munich, 82152, Planegg, Germany.
J Cell Sci. 2023 Nov 1;136(21). doi: 10.1242/jcs.260337. Epub 2023 Oct 30.
Connections between the nucleus and the cytoskeleton are important for positioning and division of the nucleus. In most eukaryotes, the linker of nucleoskeleton and cytoskeleton (LINC) complex spans the outer and inner nuclear membranes and connects the nucleus to the cytoskeleton. In opisthokonts, it is composed of Klarsicht, ANC-1 and Syne homology (KASH) domain proteins and Sad1 and UNC-84 (SUN) domain proteins. Given that the nucleus is positioned at the posterior pole of Toxoplasma gondii, we speculated that apicomplexan parasites must have a similar mechanism that integrates the nucleus and the cytoskeleton. Here, we identified three UNC family proteins in the genome of the apicomplexan parasite T. gondii. Whereas the UNC-50 protein TgUNC1 localised to the Golgi and appeared to be not essential for the parasite, the SUN domain protein TgSLP2 showed a diffuse pattern throughout the parasite. The second SUN domain protein, TgSLP1, was expressed in a cell cycle-dependent manner and was localised close to the mitotic spindle and, more detailed, at the kinetochore. We demonstrate that conditional knockout of TgSLP1 leads to failure of nuclear division and loss of centrocone integrity.
核与细胞骨架之间的连接对于核的定位和分裂非常重要。在大多数真核生物中，核骨架与细胞骨架的连接（LINC）复合物跨越核内外膜，并将核与细胞骨架连接起来。在后生动物中，它由 Klarsicht、ANC-1 和 Syne 同源（KASH）结构域蛋白以及 Sad1 和 UNC-84（SUN）结构域蛋白组成。鉴于细胞核位于刚地弓形虫的后极，我们推测顶复门寄生虫必须具有类似的将核与细胞骨架整合在一起的机制。在这里，我们在顶复门寄生虫刚地弓形虫的基因组中鉴定出三种 UNC 家族蛋白。UNC-50 蛋白 TgUNC1 定位于高尔基体，似乎对寄生虫不是必需的，而 SUN 结构域蛋白 TgSLP2 在整个寄生虫中呈现弥散模式。第二个 SUN 结构域蛋白 TgSLP1 以细胞周期依赖性方式表达，并靠近有丝分裂纺锤体，更详细地说，位于着丝粒附近。我们证明 TgSLP1 的条件敲除会导致核分裂失败和中心体完整性丧失。
