Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
Department of Cell Biology, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
Nat Cell Biol. 2015 Aug;17(8):1024-35. doi: 10.1038/ncb3204. Epub 2015 Jul 20.
Correct formation of the cell division axis requires the initial precise orientation of the mitotic spindle. Proper spindle orientation depends on centrosome maturation, and Polo-like kinase 1 (PLK1) is known to play a crucial role in this process. However, the molecular mechanisms that function downstream of PLK1 are not well understood. Here we show that LRRK1 is a PLK1 substrate that is phosphorylated on Ser 1790. PLK1 phosphorylation is required for CDK1-mediated activation of LRRK1 at the centrosomes, and this in turn regulates mitotic spindle orientation by nucleating the growth of astral microtubules from the centrosomes. Interestingly, LRRK1 in turn phosphorylates CDK5RAP2(Cep215), a human homologue of Drosophila Centrosomin (Cnn), in its γ-tubulin-binding motif, thus promoting the interaction of CDK5RAP2 with γ-tubulin. LRRK1 phosphorylation of CDK5RAP2 Ser 140 is necessary for CDK5RAP2-dependent microtubule nucleation. Thus, our findings provide evidence that LRRK1 regulates mitotic spindle orientation downstream of PLK1 through CDK5RAP2-dependent centrosome maturation.
细胞分裂轴的正确形成需要有丝分裂纺锤体的初始精确定向。适当的纺锤体定向取决于中心体成熟，而 Polo 样激酶 1（PLK1）已知在此过程中发挥关键作用。然而，PLK1 下游的分子机制尚不清楚。在这里，我们表明 LRRK1 是 PLK1 的底物，在丝氨酸 1790 上被磷酸化。PLK1 磷酸化对于 CDK1 在中心体处对 LRRK1 的激活是必需的，而这反过来又通过从中心体起始星体微管的生长来调节有丝分裂纺锤体的定向。有趣的是，LRRK1 反过来在其γ-微管蛋白结合基序中磷酸化 CDK5RAP2（Cep215），这是果蝇中心体（Cnn）的人类同源物，从而促进 CDK5RAP2 与γ-微管蛋白的相互作用。LRRK1 对 CDK5RAP2 Ser140 的磷酸化对于 CDK5RAP2 依赖性微管核形成是必需的。因此，我们的发现提供了证据表明，LRRK1 通过 CDK5RAP2 依赖性中心体成熟来调节 PLK1 下游的有丝分裂纺锤体定向。
