Disruption of the c/ebp alpha gene in adult mouse liver
Disruption of the c/ebp alpha gene in adult mouse liver
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DOI：
10.1128/mcb.17.10.6014
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发表时间：
1997-10-01
影响因子：
5.3
通讯作者：
Gonzalez, FJ
中科院分区：
文献类型：
--
作者：
Lee, YH;Sauer, B;Gonzalez, FJ
富含肝脏的转录因子C/EBP α与许多肝脏特异性基因的调控有关。先前有报道称，在C/EBP α位点携带纯合零突变的小鼠在新生儿时因肝糖原缺失和由此导致的低血糖而死亡。然而，C/EBP α的致死表型阻碍了对其在成年小鼠肝脏基因调控中的作用的进一步分析，为了解决这一问题，我们利用Cre/loxP重组系统构建了C/EBP α的条件敲除等位基因。纯合子c/ebp- loxp小鼠，(c/ebp α (fl/fl)；然而，当Cre重组酶通过携带Cre基因的重组腺病毒输注到成年c/ebp α (fl/fl)小鼠的肝细胞时，超过80%的c/ebp α (fl/fl)基因在肝脏中特异性缺失，c/ebp α的表达减少了90%。这种情况导致肝脏中胆红素- udp -葡萄糖醛酸糖基转移酶表达水平降低。几天后，由于未结合的血清胆红素增加，敲除小鼠出现了严重的黄疸。在成年条件敲除动物中，编码磷酸烯醇丙酮酸羧激酶、糖原合成酶和IX因子的基因表达也强烈降低，而转铁蛋白、载脂蛋白B和胰岛素样生长因子I基因的表达不受影响。这些结果表明，C/EBP α是成年小鼠肝脏中胆红素解毒和糖异生相关基因编码酶的重要转录调节因子。
The liver-enriched transcription factor C/EBP alpha has been implicated in the regulation of numerous liver-specific genes, It was previously reported that mice carrying a homozygous null mutation at the c/ebp alpha locus died as neonates due to the absence of hepatic glycogen and the resulting hypoglycemia. However, the lethal phenotype precluded further analysis of the role of C/EBP alpha in hepatic gene regulation in adult mice, To circumvent this problem, we constructed a conditional knockout allele of c/ebp alpha by using the Cre/loxP recombination system. Homozygous c/ebp-loxP mice, (c/ebp alpha(fl/fl); fl, flanked by loxP sites) were found to be indistinguishable from their wild-type counterparts, However, when Cre recombinase was delivered to hepatocytes of adult c/ebp alpha(fl/fl) mice by infusion of a recombinant adenovirus carrying the cre gene, more than 80% of the c/ebp alpha(fl/fl) genes were deleted specifically in liver and C/EBP alpha expression was reduced by 90%. This condition resulted in a reduced level of bilirubin UDP-glucuronosyltransferase expression in the liver. After several days, the knockout mice del eloped severe jaundice due to an increase in unconjugated serum bilirubin. The expression of genes encoding phosphoenolpyruvate carboxykinase, glycogen synthase, and factor IX was also strongly reduced in adult conditional-knockout animals, while the expression of transferrin, apolipoprotein B, and insulin-like growth factor I genes was not affected. These results establish C/EBP alpha as an essential transcriptional regulator of genes encoding enzymes involved in bilirubin detoxification and gluconeogenesis in adult mouse liver.