Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan.
Sci Rep. 2023 Feb 4;13(1):2067. doi: 10.1038/s41598-023-29362-w.
Mitotic progression requires the precise formation of spindle microtubules based on mature centrosomes. During the G2/M transition, centrosome maturation progresses, and associated microtubules bundle to form mitotic spindle fibers and capture the chromosomes for alignment at the cell equator. Mitotic kinases-induced phosphorylation signaling is necessary for these processes. Here, we identified SH2 domain-containing protein 4A (SH2D4A/PPP1R38) as a new mitotic regulator. SH2D4A knockdown delays mitotic progression. The time-lapse imaging analysis showed that SH2D4A specifically contributes to the alignment of chromosomes. The cold treatment assay and microtubule regrowth assay indicated that SH2D4A promotes microtubule nucleation to support kinetochore-microtubule attachment. This may be due to the centrosome maturation by SH2D4A via centrosomal recruitment of pericentriolar material (PCM) such as cep192, γ-tubulin, and PLK1. SH2D4A was found to be a negative regulator of PP1 phosphatase. Consistently, treatment with a PP1 inhibitor rescues SH2D4A-knockdown-induced phenotypes, including the microtubule nucleation and centrosomal recruitment of active PLK1. These results suggest that SH2D4A is involved in PCM recruitment to centrosomes and centrosome maturation through attenuation of PP1 phosphatases, accelerating the spindle formation and supporting mitotic progression.
有丝分裂的进行需要基于成熟中心体精确地形成纺锤体微管。在 G2/M 转换期间，中心体成熟进展，相关微管束形成有丝分裂纺锤体纤维，并捕获染色体以在细胞赤道处对齐。有丝分裂激酶诱导的磷酸化信号对于这些过程是必需的。在这里，我们鉴定了 SH2 结构域蛋白 4A（SH2D4A/PPP1R38）作为一种新的有丝分裂调节剂。SH2D4A 的敲低会延迟有丝分裂的进行。延时成像分析表明，SH2D4A 特异性地有助于染色体的排列。冷处理试验和微管再生试验表明，SH2D4A 促进微管核形成以支持动粒-微管附着。这可能是由于 SH2D4A 通过中心体募集中心粒周围物质（PCM），如 cep192、γ-微管蛋白和 PLK1，从而促进中心体成熟。发现 SH2D4A 是 PP1 磷酸酶的负调节剂。一致地，用 PP1 抑制剂处理可挽救 SH2D4A 敲低诱导的表型，包括微管核形成和活性 PLK1 的中心体募集。这些结果表明，SH2D4A 通过衰减 PP1 磷酸酶参与 PCM 向中心体的募集和中心体成熟，从而加速纺锤体形成并支持有丝分裂的进行。
