A-431 CELLS AND HUMAN KERATINOCYTES SYNTHESIZE AND SECRETE THE 3RD COMPONENT OF COMPLEMENT
A-431 CELLS AND HUMAN KERATINOCYTES SYNTHESIZE AND SECRETE THE 3RD COMPONENT OF COMPLEMENT
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DOI：
10.1111/1523-1747.ep12513524
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发表时间：
1990-12-01
影响因子：
6.5
通讯作者：
YANCEY, KB
中科院分区：
文献类型：
--
作者：
BASSETSEGUIN, N;CAUGHMAN, SW;YANCEY, KB
生物合成放射性标记研究表明，人表皮样癌细胞系A-431细胞和角质形成细胞以120和75kD的两条二硫键连接的多肽链的形式合成和分泌C3。此外，上皮细胞来源的C3在SDS-PAGE中与以前用于阐明补体成分生物合成的人肝癌细胞系HepG2产生的C3共同迁移。在A-431细胞中的脉冲追逐研究表明，上皮细胞来源的C3是作为195-kD的前体分子，原-C3在细胞内通过有限的蛋白质分解而被加工成120-和75-kD的C3α和β链。比较研究表明，A-431细胞来源的C3的合成、加工和分泌是平行的，但数量低于HepG2细胞。用正常人血清和酵母多糖处理生物合成标记的A-431细胞培养上清，产生C3α链断裂和特定的C3片段，这在用热灭活的人血清和酵母多糖处理的对照培养上清液中不存在。从A-431细胞、人角质形成细胞和HepG2细胞中提取的总细胞RNA的Northern杂交分析表明，这三种细胞类型中的5.1kb C3mRNA种类在质量上是相同的。上皮细胞来源的C3可能在包括人体皮肤在内的局部炎症和免疫反应中发挥重要作用。此外，上皮细胞C3的合成可能与最近在选定的正常灵长类上皮基膜(包括表皮基膜)内C3d，g的存在有直接关系。
Biosynthetic radiolabeling studies demonstrate that A-431 cells, a human epidermoid carcinoma cell line, and human keratinocytes synthesize and secrete C3 as two disulfide-linked polypeptide chains of 120 and 75 kD. Moreover, epithelial cell-derived C3 co-migrates in SDS-PAGE with that produced by HepG2 cells, a human hepatoma cell line previously used to elucidate complement component biosynthesis. Pulse-chase studies in A-431 cells demonstrate that epithelial cell-derived C3 is produced as a 195-kD precursor molecule, pro-C3, which is processed intracellularly by limited proteolysis into 120- and 75-kD C3 alpha and beta chains. Comparative studies demonstrate that A-431 cell-derived C3 is synthesized, processed, and secreted in parallel but in lower quantity than that produced by HepG2 cells. Treatment of biosynthetically labeled A-431 cell culture supernatants with normal human serum and zymosan produces C3 alpha chain cleavage and specific C3 fragments that are not present in control culture supernatants treated with heat-inactivated human serum and zymosan. Northern blot analysis of total cellular RNA extracted from A-431 cells, human keratinocytes, and HepG2 cells reveals qualitative identity of a 5.1-kb C3 mRNA species in these three cell types. Epithelial cell-derived C3 may play an important role in local inflammatory and immunologic reactions including such reactions in human skin. Moreover, epithelial cell C3 synthesis may have direct relevance to the recent demonstration of C3d,g within selected normal primate epithelial basement membranes, including epidermal basement membrane.