Genetic disruption of the murine complement C3 promoter region generates deficient mice with extrahepatic expression of C3 mRNA
Genetic disruption of the murine complement C3 promoter region generates deficient mice with extrahepatic expression of C3 mRNA
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DOI：
10.1016/s0162-3109(99)00021-1
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发表时间：
1999-05-01
期刊：
影响因子：
--
通讯作者：
Colten, HR
中科院分区：
文献类型：
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作者：
Circolo, A;Garnier, G;Colten, HR
补体蛋白C3的遗传缺陷在人类和动物模型中是自然发生的，并已在小鼠中通过C3基因的定向缺失而诱导。对这些缺陷的研究为C3在免疫反应中的作用提供了证据。用新霉素抗性(Neo)基因替换C3基因的5‘侧翼区，产生C3缺陷小鼠。这些小鼠的血清没有检测到C3蛋白或补体活性。与肺炎链球菌的挑战显示，与同年龄对照相比，菌血症增加了约2000倍。C3mRNA在肝脏中缺失，但在肺、肾、脂肪组织、心脏和脾中可检测到。肺组织和腹膜巨噬细胞的代谢标记显示合成了原C3，但没有合成后细胞内加工和成熟C3的分泌。帽部位的cDNA分析表明，靶基因的肝外转录是在靠近C3/neo连接的地方启动的，并预测了一个初级翻译产物，缺少先导肽。这些数据表明，这些小鼠为研究完全性C3缺乏症提供了一个很好的动物模型，并为组织特异性C3基因调控元件提供了一个潜在的探针。(C)1999 Elsevier Science B.V.保留所有权利。
Genetic deficiencies of the complement protein C3 occur naturally in humans and animal models and have been induced in mice by targeted deletion of the C3 gene. The study of these deficiencies has provided evidence for C3 functions in immune responses. C3 deficient mice were generated by replacing the 5'-flanking region of the C3 gene with the neomycin-resistance (neo) gene. Serum from these mice had no detectable C3 protein or complement activity. Challenge with Streptococcus pneumoniae revealed approximately 2000-fold increase in bacteremia as compared to littermate controls. C3 mRNA was absent in the liver, but it was detected in the lung, kidney, fat tissue, heart and spleen. Metabolic labeling of the lung tissue and peritoneal macrophages showed synthesis of pro-C3, but no post-synthetic intracellular processing of the protein and no secretion of mature C3, cDNA analysis at the cap site indicated that extrahepatic transcription of the targeted gene was initiated in the neo cassette, close to the C3/neo junction and predicted a primary translation product lacking the leader peptide. The data indicate that these mice provide a good animal model for the study of complete C3 deficiencies and a potential probe for tissue-specific C3 gene regulatory elements. (C) 1999 Elsevier Science B.V. All rights reserved.