Santos Mariana, Costa Patrícia, Martins Filipa, da Cruz e Silva Edgar F, da Cruz e Silva Odete A B, Rebelo Sandra
Neuroscience Laboratory, Health Sciences Department, Centre for Cell Biology, University of Aveiro, 3810-193, Aveiro, Portugal.
Mol Cell Biochem. 2015 Jan;399(1-2):143-53. doi: 10.1007/s11010-014-2241-x. Epub 2014 Oct 17.
Cell division in eukaryotes requires the disassembly of the nuclear envelope (NE) at the beginning of mitosis and its reassembly at the end of mitosis. These processes are complex and involve coordinated steps where NE proteins have a crucial role. Lamina-associated polypeptide 1 (LAP1) is an inner nuclear membrane protein that has been associated with cell cycle events. In support of this role, LAP1 has been implicated in the regulation of the NE reassembly and assembly of the mitotic spindle during mitosis. In this study, we demonstrated that LAP1 intracellular levels vary during the cell cycle in SH-SY5Y cells, and that LAP1 is highly phosphorylated during mitosis. It is also clear that LAP1 co-localized with acetylated α-tubulin in the mitotic spindle and with γ-tubulin in centrosomes (main microtubule organizing center) in mitotic cells. Moreover, LAP1 knockdown resulted in decreased number of mitotic cells and decreased levels of acetylated α-tubulin (marker of microtubules stability) and lamin B1. Additionally, it was possible to determine that LAP1 is important for centrosome positioning near the NE. These findings place LAP1 at a key position to participate in the maintenance of the NE structure and progression of the cell cycle.
真核生物中的细胞分裂需要在有丝分裂开始时核膜（NE）解体，并在有丝分裂结束时重新组装。这些过程很复杂，涉及多个协调步骤，其中NE蛋白起着关键作用。核纤层相关多肽1（LAP1）是一种内核膜蛋白，与细胞周期事件有关。为支持这一作用，LAP1参与了有丝分裂期间NE的重新组装以及有丝分裂纺锤体的组装。在本研究中，我们证明了在SH-SY5Y细胞中，LAP1的细胞内水平在细胞周期中有所变化，并且LAP1在有丝分裂期间高度磷酸化。同样明确的是，在有丝分裂细胞中，LAP1在有丝分裂纺锤体中与乙酰化α-微管蛋白共定位，在中心体（主要微管组织中心）中与γ-微管蛋白共定位。此外，敲低LAP1导致有丝分裂细胞数量减少，乙酰化α-微管蛋白（微管稳定性标志物）和核纤层蛋白B1水平降低。此外，还可以确定LAP1对于中心体定位在NE附近很重要。这些发现使LAP1处于参与维持NE结构和细胞周期进程的关键位置。
