p53-mediated biliary defects caused by knockdown of cirh1a, the zebrafish homolog of the gene responsible for North American Indian Childhood Cirrhosis.
p53-mediated biliary defects caused by knockdown of cirh1a, the zebrafish homolog of the gene responsible for North American Indian Childhood Cirrhosis.
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DOI：
10.1371/journal.pone.0077670
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Pack M
中科院分区：
文献类型：
--
作者：
Wilkins BJ;Lorent K;Matthews RP;Pack M
北美印第安儿童肝硬化（NAIC）是一种罕见的常染色体隐性进行性胆汁淤积症，发生在魁北克省的Cree-Ojibway第一民族。所有NAIC患者都是CIRH1A错义突变（R565W）的纯合子，CIRH1A是酵母核仁蛋白Utp4的人类同源物。Utp4是小亚基（SSU）加工体的t-Utp亚复合物的一部分，是核糖体RNA加工和小亚基组装所需的核糖核蛋白复合物。因此，NAIC被认为是一种原发性核糖体疾病（核糖体病）；然而，由于缺乏动物模型，对该病病理生理机制的研究一直受到阻碍。在这里，使用基于morpholino寡核苷酸（MO）的功能丧失策略，我们在斑马鱼Danio版本中生成了NAIC模型。斑马鱼的Cirhin与人类的cirh1a同源性相当，cirh1a mRNA在发育中的肝细胞和胆道上皮细胞中表达。在单细胞期注射两种独立的针对cirh1a的MOs，会导致5只dpf幼虫的小管和胆道形态出现缺陷。此外，通过摄入的荧光脂质报告物代谢检测，5种dpf cirhin缺陷幼虫在肝胆功能上存在剂量依赖性缺陷。先前的酵母和体外研究表明，核糖体生物发生缺陷导致p53的稳定和核积累，进而导致p53介导的细胞周期阻滞和/或凋亡。因此，核仁似乎在某些细胞类型中起细胞应激传感器的作用。根据这一假说，p53的转录靶点在cirhin缺陷的斑马鱼胚胎中上调，而在cirhin缺陷的幼虫中出现的胆道功能缺陷被tp53的突变完全消除。我们的数据首次在体内证明了Cirhin在胆道发育中的作用，并支持了影响核糖体生物发生的先天性缺陷可以激活p53介导的细胞应激反应的假设。
North American Indian Childhood Cirrhosis (NAIC) is a rare, autosomal recessive, progressive cholestatic disease of infancy affecting the Cree-Ojibway first Nations of Quebec. All NAIC patients are homozygous for a missense mutation (R565W) in CIRH1A, the human homolog of the yeast nucleolar protein Utp4. Utp4 is part of the t-Utp subcomplex of the small subunit (SSU) processome, a ribonucleoprotein complex required for ribosomal RNA processing and small subunit assembly. NAIC has thus been proposed to be a primary ribosomal disorder (ribosomopathy); however, investigation of the pathophysiologic mechanism of this disease has been hindered by lack of an animal model. Here, using a morpholino oligonucleotide (MO)-based loss-of-function strategy, we have generated a model of NAIC in the zebrafish, Danio rerio. Zebrafish Cirhin shows substantial homology to the human homolog, and cirh1a mRNA is expressed in developing hepatocytes and biliary epithelial cells. Injection of two independent MOs directed against cirh1a at the one-cell stage causes defects in canalicular and biliary morphology in 5 dpf larvae. In addition, 5 dpf Cirhin-deficient larvae have dose-dependent defects in hepatobiliary function, as assayed by the metabolism of an ingested fluorescent lipid reporter. Previous yeast and in vitro studies have shown that defects in ribosome biogenesis cause stabilization and nuclear accumulation of p53, which in turn causes p53-mediated cell cycle arrest and/or apoptosis. Thus, the nucleolus appears to function as a cellular stress sensor in some cell types. In accordance with this hypothesis, transcriptional targets of p53 are upregulated in Cirhin-deficient zebrafish embryos, and defects in biliary function seen in Cirhin-deficient larvae are completely abrogated by mutation of tp53. Our data provide the first in vivo evidence of a role for Cirhin in biliary development, and support the hypothesis that congenital defects affecting ribosome biogenesis can activate a cellular stress response mediated by p53.
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影响因子：
2.6
作者：
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