Zhang Qian, Wang Ya-Zhou, Zhang Wenbin, Chen Xiaoming, Wang Jiye, Chen Jingyuan, Luo Wenjing
Department of Occupational and Environmental Health, the Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an, Shaanxi, 710032, China.
Department of Neurobiology and Collaborative Innovation Center for Brain Science, School of Basic Medicine, Fourth Military Medical University, 169 Chang Le Xi Road, Xi'an, Shaanxi, 710032, China.
Mol Neurobiol. 2017 Apr;54(3):2143-2153. doi: 10.1007/s12035-016-9761-1. Epub 2016 Mar 1.
Neonatal hypoxia is the leading cause of brain damage with birth complications. Many studies have reported proliferation-promoting effect of mild hypoxia on neural stem cells (NSCs). However, how severe hypoxia influences the behavior of NSCs has been poorly explored. In the present study, we investigated the effects of 5, 3, and 1 % oxygen exposure on NSCs in vitro. MTT, neurosphere assay, and 5-ethynyl-2'-deoxyuridine (EdU) incorporation revealed a quick growth arrest of C17.2 cells and primary NSCs induced by 1 % oxygen exposure. Cell cycle analysis showed that this hypoxia exposure caused a significant increase of cells in G0/G1 phase and decrease of cells in S phase that is associated with decrease of Cyclin D1. Interestingly, the expression of cold inducible RNA-binding protein (CIRBP), a cold responsive gene reacting to multiple cellular stresses, was decreased in parallel with the 1 % oxygen-induced proliferation inhibition. Forced expression of CIRBP under hypoxia could restore the proliferation of NSCs, as showed by EdU incorporation and cell cycle analysis. Furthermore, the expression of Cyclin D1 under hypoxia was also restored by CIRBP overexpression. Taken together, these data suggested a growth-suppressing effect of severe hypoxia on NSCs and, for the first time, revealed a novel role of CIRBP in hypoxia-induced cell cycle arrest, suggesting that modulating CIRBP may be utilized for preventing hypoxia-induced neonatal brain injury.
新生儿缺氧是出生并发症导致脑损伤的主要原因。许多研究报道了轻度缺氧对神经干细胞（NSCs）的促增殖作用。然而，严重缺氧如何影响神经干细胞的行为尚未得到充分研究。在本研究中，我们调查了5%、3%和1%氧气暴露对体外神经干细胞的影响。MTT法、神经球测定法和5-乙炔基-2'-脱氧尿苷（EdU）掺入法显示，1%氧气暴露诱导C17.2细胞和原代神经干细胞快速生长停滞。细胞周期分析表明，这种缺氧暴露导致G0/G1期细胞显著增加，S期细胞减少，这与细胞周期蛋白D1的减少有关。有趣的是，冷诱导RNA结合蛋白（CIRBP）的表达，一种对多种细胞应激有反应的冷反应基因，与1%氧气诱导的增殖抑制同时降低。缺氧条件下CIRBP的强制表达可恢复神经干细胞的增殖，EdU掺入法和细胞周期分析表明了这一点。此外，CIRBP过表达也恢复了缺氧条件下细胞周期蛋白D1的表达。综上所述，这些数据表明严重缺氧对神经干细胞有生长抑制作用，并且首次揭示了CIRBP在缺氧诱导的细胞周期停滞中的新作用，表明调节CIRBP可用于预防缺氧诱导的新生儿脑损伤。
