Nagata Yuka, Jones Matthew R, Nguyen Hao G, McCrann Donald J, St Hilaire Cynthia, Schreiber Barbara M, Hashimoto Atsushi, Inagaki Masaki, Earnshaw William C, Todokoro Kazuo, Ravid Katya
Recognition and Formation, Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Japan.
Exp Cell Res. 2005 May 1;305(2):277-91. doi: 10.1016/j.yexcr.2004.12.028.
Vascular smooth muscle cell polyploidization occurs during normal development and is enhanced under physiologic stress, but the mechanism of this cell cycle has not been explored. We show via time-lapse video imaging and immunofluorescence analyses that primary vascular smooth muscle cells (VSMC) undergo an endomitotic-type cell cycle, including a normal progression through part of mitosis. Mononuclear polyploid cells are generated by defects in sister chromatid separation and/or segregation, and cellular binucleation occurs by reversal of cytokinesis. To obtain further leads to regulators involved, we examined the chromosomal passenger proteins, Aurora B, inner centromere protein and Survivin, and concluded that Aurora B and inner centromere protein are normally colocalized in centromeres, the midzone, and the midbody during mitosis. Survivin, however, is dim and diffused; it does not colocalize with either Aurora B or inner centromere protein in VSMC, which could account for defects in sister chromatid separation and/or segregation and reversal of cytokinesis. In accordance with the reported dependency of Aurora B activity on Survivin, the Aurora B substrate, vimentin, is not phosphorylated during cytokinesis. Finally, the data show that ectopically expressed Survivin inhibits polyploidization in vascular smooth muscle cells. Hence, aberrant chromosome passenger protein activity and endomitosis are associated with VSMC polyploidization.
血管平滑肌细胞多倍体化在正常发育过程中发生，并在生理应激下增强，但这种细胞周期的机制尚未被探索。我们通过延时视频成像和免疫荧光分析表明，原代血管平滑肌细胞（VSMC）经历一种核内有丝分裂型细胞周期，包括部分有丝分裂的正常进程。单核多倍体细胞是由姐妹染色单体分离和/或分离缺陷产生的，细胞双核化是由胞质分裂的逆转发生的。为了进一步寻找相关调节因子，我们检测了染色体乘客蛋白Aurora B、着丝粒内蛋白和生存素，得出结论：在有丝分裂期间，Aurora B和着丝粒内蛋白通常共定位于着丝粒、中间区和中间体。然而，生存素暗淡且弥散；它在VSMC中不与Aurora B或着丝粒内蛋白共定位，这可能解释了姐妹染色单体分离和/或分离以及胞质分裂逆转的缺陷。根据报道的Aurora B活性对生存素的依赖性，Aurora B的底物波形蛋白在胞质分裂期间未被磷酸化。最后，数据表明异位表达的生存素抑制血管平滑肌细胞的多倍体化。因此，异常的染色体乘客蛋白活性和核内有丝分裂与VSMC多倍体化相关。
