Human factor H deficiency - Mutations in framework cysteine residues and block in H protein secretion and intracellular catabolism
Human factor H deficiency - Mutations in framework cysteine residues and block in H protein secretion and intracellular catabolism
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DOI：
10.1074/jbc.272.40.25168
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发表时间：
1997-10-03
影响因子：
4.8
通讯作者：
Colten, HR
中科院分区：
文献类型：
--
作者：
Ault, BH;Schmidt, BZ;Colten, HR
在患有慢性低补体血症肾病的 H 缺乏儿童的皮肤成纤维细胞中研究了 H 因子（补体系统的调节蛋白）的合成和分泌。在正常成纤维细胞中，4.3 和 1.8 千碱基对 (kb) 的 H 因子转录物分别编码包含短共有重复 (SCR) 结构域 1-20 的 155 kDa 蛋白质和包含 SCR 1-7 的 45 kDa 蛋白质。患者的成纤维细胞在肿瘤坏死因子-α/干扰素-γ刺激后组成型表达正常量的4.3-和1.8-kb信息。来自患者的[S-35]蛋氨酸标记的成纤维细胞的裂解物含有155-和45-kDa H多肽，但155-kDa蛋白的分泌被阻断； 45-kDa 蛋白以正常动力学分泌，患者血浆缺乏 155-kDa 蛋白，但含有小形式的 H。此外，在成纤维细胞中，即使在 12 小时后，保留的 155-kDa 因子 H 蛋白也没有降解。患者成纤维细胞的免疫荧光染色和共聚焦显微成像表明，因子 H 保留在内质网中，反向序列分析转录聚合酶链式反应产物（整个编码区）和基因组 DNA 显示一个等位基因上有 T1679C 取代，另一个等位基因上有 G2949A 取代（分别是 SCR 9 中的 C518R 突变和 SCR 16 中的 C991Y 突变），这两种突变都会影响 SCR 模块的保守半胱氨酸残基特征，因此预测 155-kDa 因子 H 蛋白的高级结构中的明显变化。这些数据提供了第一个描述H 因子缺乏的分子机制，并对这种和其他具有 SCR 基序的血浆蛋白的正常分泌途径产生重要的见解。
The synthesis and secretion of factor H, a regulatory protein of the complement system, were studied in skin fibroblasts from an H-deficient child who has chronic hypocomplementemic renal disease, In normal fibro blasts, factor H transcripts of 4.3 and 1.8 kilobase pairs (kb) encode a 155-kDa protein containing short consensus repeat (SCR) domains 1-20 and a 45-kDa protein which contains SCRs 1-7, respectively. The patient's fibroblasts expressed normal amounts of the 4.3- and 1.8-kb messages constitutively and after tumor necrosis factor-alpha/interferon-gamma stimulation. Lysates of [S-35]methionine-labeled fibroblasts from the patient contained the 155- and 45-kDa H polypeptides, but secretion of the 155-kDa protein was blocked; the 45-kDa protein was secreted with normal kinetics, The patient's plasma lacked the 155-kDa protein but contained the small form of H. Moreover, in fibroblasts the retained 155-kDa factor H protein was not degraded, even after 12 h, Immunoflourescent staining and confocal microscopic imaging of the patient's fibroblasts indicated that factor H was retained in the endoplasmic reticulum, Sequence analysis of reverse transcription-polymerase chain reaction products (the entire coding region) and genomic DNA revealed a T1679C substitution on one allele and a G2949A substitution on the other (C518R mutation in SCR 9 and C991Y mutation in SCR 16, respectively), Both mutations affect conserved cysteine residues characteristic of SCR modules and therefore predict pro found changes in the higher order structure of the 155-kDa factor H protein, These data provide the first description of a molecular mechanism for factor H deficiency and yield important insights into the normal secretory pathway for this and other plasma proteins with SCR motifs.