敲除eIF4B基因对小鼠胚胎肝脏细胞凋亡的影响

Effect of eIF4B knockout on apoptosis of mouse fetal liver cells

摘要:

真核翻译起始因子4B (eukaryotic translation initiation factor 4B,eIF4B)在mRNA翻译起始、细胞存活和增殖过程中发挥着关键作用，然而其在生物体内的生物学功能仍存在许多疑问。本研究利用eIF4B基因敲除小鼠模型，结合苏木精和伊红(hematoxylin-eosin,HE)染色、流式细胞术、Western blotting和免疫组化等一系列实验技术手段，探究了eIF4B在胚胎发育过程中的功能及作用机理。结果显示，eIF4B敲除小鼠胚胎的肝脏呈现严重病理损伤，主要表现为胚肝细胞的凋亡和坏死，而小鼠胚胎的肺脏、脑、胃和胰腺则发育正常。进一步研究发现，在eIF4B敲除小鼠的胚胎肝脏中活化型caspase 3(cleaved-caspase 3)的表达水平显著升高。此外，eIF4B敲除小鼠的胚胎成纤维细胞和胚胎肝脏中mTOR通路下游信号分子p70S6K的表达和磷酸化水平以及4EBP1的磷酸化水平显著升高。综上所述，eIF4B敲除导致cleaved-caspase 3表达增加和mTOR信号通路过度活化，促进胚肝细胞的凋亡，致使小鼠胚肝发育异常，最终引发小鼠胚胎死亡。本研究揭示了eIF4B在胚胎发育过程中的重要作用，为深入了解eIF4B在生物体内的生物学功能提供了新的科学依据。

Abstract:

Eukaryotic translation initiation factor 4B (eIF4B) plays an important role in mRNA translation initiation, cell survival and proliferation in vitro, but the in vivo function is poorly understood. In this study, via various experimental techniques such as hematoxylin-eosin (HE) staining, flow cytometry, Western blotting, and immunohistochemistry, we investigated the role of eIF4B in mouse embryo development using an eIF4B knockout (KO) mouse model and explored the mechanism. We found that the livers, but not lungs, brain, stomach, or pancreas, derived from eIF4B KO mouse embryos displayed severe pathological changes characterized by enhanced apoptosis and necrosis. Accordingly, high expression of cleaved-caspase 3, and excessive activation of mTOR signaling as evidenced by increased expression and phosphorylation of p70S6K and enhanced phosphorylation of 4EBP1, were observed in mouse embryonic fibroblasts and fetal livers from eIF4B KO mice. These results uncover a critical role of eIF4B in mouse embryo development and provide important insights into the biological functions of eIF4B in vivo.