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Identification of hepatic stem cells and development of its separation methods : Analysis of the self-replication and survival of the cells

肝干细胞的鉴定及其分离方法的开发：分析细胞的自我复制和存活

基本信息

批准号：
13558083
负责人：
NISHINA Hiroshi
金额：
$ 8.9万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Mice lacking stress-signaling kinase SEK1 die from embryonic day 10.5 (El0.5) to E12.5. Although a defect in liver formation is accompanied with the embryonic lethality of sek1-/- mice, the mechanism leading to the liver defect has remained unknown. Here we investigated liver development in sek1-/- embryos using a monoclonal antibody specifically recognizing murine hepatoblasts and genetic interaction of sek1 with proto-oncogene c-jun and tumor necrosis factor-α receptor 1 gene, tnfrl, which are also responsible for liver formation and the cell apoptosis. There was a progressive increase in the hepatoblast cell numbers of wild-type embryos from E10.5 to 12.5. The hepatoblast proliferation required no hematopoiesis, since transcription factor AML1-deficient mice had no defect in the cell growth. Instead, impaired hepatoblast proliferation was observed in sekl-/- livers from E10.5, though fetal liver-specific gene expression was normal. The impaired phenotype in sek1-/- livers was more severe than in c-jun-/- embryos, and sek1-/- c-jun-/- embryos more rapidly died before E8.5. Stimulation of stress-activatied protein kinase/c-Jun N-terminal kinase by hepatocyte growth factor was attenuated in sek1-/- livers. The defective liver formation in sek1-/- embryos was not protected by additional tnfr1 mutation that rescues the embryonic lethality of mice lacking NF-kB signaling components. Thus, SEK1 appears to play a crucial role in hepatoblast proliferation and survival in a manner apparently different from c-Jun or NF-kB.

缺乏应激信号激酶SEK1的小鼠在胚胎10.5天（El0.5）至E12.5天死亡。虽然肝脏形成缺陷伴随着sek1-/-小鼠的胚胎死亡，但导致肝脏缺陷的机制仍不清楚。本研究使用特异性识别小鼠肝母细胞的单克隆抗体研究了sek1-/-胚胎的肝脏发育，以及sek1与原癌基因c-jun和肿瘤坏死因子-α受体1基因tnfrl的遗传相互作用，这两个基因也负责肝脏的形成和细胞凋亡。野生型胚胎的肝母细胞数从E10.5逐渐增加到12.5。肝母细胞增殖不需要造血，因为转录因子aml1缺陷小鼠的细胞生长没有缺陷。相反，尽管胎儿肝脏特异性基因表达正常，但在E10.5的sekl-/-肝脏中观察到成肝细胞增殖受损。与c-jun-/-胚胎相比，sek1-/-肝脏的表型受损更为严重，sek1-/- c-jun-/-胚胎在E8.5之前死亡更快。肝细胞生长因子对应激激活蛋白激酶/c-Jun n -末端激酶的刺激在sek1-/-肝脏中减弱。在缺乏NF-kB信号成分的小鼠中，额外的tnfr1突变不能保护sek1-/-胚胎中有缺陷的肝脏形成。因此，SEK1似乎以明显不同于c-Jun或NF-kB的方式在成肝细胞增殖和存活中发挥关键作用。