Kulics J, Circolo A, Strunk R C, Colten H R
Division of Allergy and Pulmonary Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St Louis Children's Hospital, Missouri 63110.
Immunology. 1994 Aug;82(4):509-15.
Synthesis and secretion of the class III major histocompatibility complex (MHC) gene product, C4, were detected in human skin fibroblasts by metabolic labelling, immunoprecipitation and SDS-PAGE analysis. Pro-C4 (approximately 185,000 MW) was present in intracellular lysates, and the mature protein was present in extracellular media, with three bands of approximately 93,000, 75,000 and 33,000 MW, corresponding to the alpha, beta and gamma chains, respectively. C4 expression was increased in a dose-dependent manner by interferon-gamma (IFN-gamma), but was unaffected by interleukin-1 beta (IL-1 beta), IL-6 and tumor necrosis factor-alpha (TNF-alpha) alone, each of which augmented the expression of factor B, C3 and other complement proteins synthesized in fibroblasts. Simultaneous incubation of fibroblasts with IFN-gamma and TNF resulted in a synergistic increase in C4 synthesis. RNA blot analyses indicated that regulation of C4 synthesis by IFN-gamma and the combination of IFN-gamma and TNF was mediated primarily at a pretranslational level. Lipopolysaccharide (LPS) had no effect on C4 or HLA-DR synthesis in fibroblasts, either constitutive or IFN-gamma-regulated. These results are in contrast to the effects of LPS in monocytes, where LPS decreased constitutive synthesis and counter-regulated the IFN-gamma-enhanced expression of both C4 and HLA-DR. C2 expression in fibroblasts was also increased primarily by IFN-gamma. However, C2 synthesis was increased by LPS, 1L-1 and TNF, although to a lesser extent than the increase in synthesis of factor B stimulated by these mediators. These results show that up-regulation by IFN-gamma is a common feature of C2 and C4 expression in human cells that constitutively synthesize these proteins. In contrast, regulation of MHC class III and class II genes by LPS, TNF, IL-1, and IL-6 is cell- and gene-specific.
通过代谢标记、免疫沉淀和SDS-PAGE分析，在人皮肤成纤维细胞中检测到III类主要组织相容性复合体（MHC）基因产物C4的合成与分泌。前体C4（约185,000分子量）存在于细胞内裂解物中，成熟蛋白存在于细胞外培养基中，有三条带，分子量分别约为93,000、75,000和33,000，分别对应α、β和γ链。干扰素-γ（IFN-γ）以剂量依赖性方式增加C4表达，但单独的白细胞介素-1β（IL-1β）、IL-6和肿瘤坏死因子-α（TNF-α）对其无影响，而这几种因子各自均可增强成纤维细胞中合成的因子B、C3和其他补体蛋白的表达。成纤维细胞与IFN-γ和TNF同时孵育会导致C4合成协同增加。RNA印迹分析表明，IFN-γ以及IFN-γ与TNF的组合对C4合成的调节主要在翻译前水平介导。脂多糖（LPS）对成纤维细胞中C4或HLA-DR的组成性合成或IFN-γ调节的合成均无影响。这些结果与LPS对单核细胞的作用形成对比，在单核细胞中，LPS会降低组成性合成，并对IFN-γ增强的C4和HLA-DR表达产生反向调节。成纤维细胞中C2的表达也主要由IFN-γ增加。然而，LPS、IL-1和TNF会增加C2的合成，尽管其程度小于这些介质刺激的因子B合成的增加程度。这些结果表明，IFN-γ上调是在组成性合成这些蛋白的人细胞中C２和C4表达的共同特征。相比之下，LPS、TNF、IL-1和IL-6对MHC III类和II类基因的调节具有细胞和基因特异性。
