Biological activity of complement fragment Ba

补体片段Ba的生物活性

• 批准号: 08670522
• 负责人: HORIUCHI Takahiko
• 金额: $ 1.34万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08670522/
• 关键词: Complement; cgtokine; deficiency

Ba is one of the fragments of complement proteins that is generated upon activation of complement system. Ba is cleaved from factor B by factor D that belongs to the altemative pathway of complement system. Recently, the biological effects on the lymphocytes and macrophages have been reported in the Ba fragment of factor B.However the further investigation of the biological functions of Ba has been hampered mainly by the difficulty in purifying Ba in a large amount that needs many Purified complement proteins and very much complicated purifilcation steps. We intended to circumvent this laborious procedures by making recombinant Ba fragment.A full-length cDNA for factor B was isolated from the human liver cDNA library. As Ba (234 amino acid residues) corresponds to the amino terminal one third of factor B,we introduced a stop codon at the 235th amino acid residue by using site-directed mutagenesis. The mutant factor B cDNA coding for Ba fragment was trnsfected and expressed in CHO cells. The culture media containing has been subjected to the purification of recombinant Ba by using an affinity column.The association of deficiencies in the complement proteins and bacterial/viral infections and autoimmune diseases has been implicated. The molecular defects leading to the complement deficiencies has not been studied in detail. We studied the molecular bases for C6, C7, C8 and C9 deficiencies that are important in the activation of factor B.We first identified the genetic abnormalities in the deficiencies of C6 and C7. A two kinds of homozygous lbp deletion were shown in two patients with C6 deficiency, while a nonsense mutation and a 2bp deletion were identified in two patients with C7 deficiency, respectively. We have shown a nonense mutation at Arg-95 was predominant in Japanese C9 deciciency.

Ba是补体蛋白的片段之一，在补体系统激活后产生。Ba被因子D从因子B中分离出来，属于补体系统的替代途径。近年来，已报道了b因子Ba片段对淋巴细胞和巨噬细胞的生物学作用，但Ba的生物学功能的进一步研究一直受到阻碍，主要原因是Ba难以大量纯化，需要纯化许多补体蛋白，纯化步骤非常复杂。我们打算通过制作重组Ba片段来绕过这一繁琐的程序。从人肝脏cDNA文库中分离到全长的B因子cDNA。由于Ba（234个氨基酸残基）对应因子B的氨基末端1 / 3，我们采用定点诱变的方法在第235个氨基酸残基上引入了一个终止密码子。编码Ba片段的突变因子B cDNA在CHO细胞中转染表达。用亲和柱对含有重组Ba的培养基进行纯化。补体蛋白缺乏与细菌/病毒感染和自身免疫性疾病之间存在关联。导致补体缺陷的分子缺陷尚未得到详细的研究。我们研究了C6， C7， C8和C9缺陷的分子基础，这些缺陷在b因子的激活中很重要。我们首先确定了C6和C7缺陷的遗传异常。在两例C6缺乏症患者中发现了两种纯合lbp缺失，在两例C7缺乏症患者中分别发现了无义突变和2bp缺失。我们已经证明Arg-95的无意义突变在日本C9缺陷中占主导地位。

项目成果

Horiuchi T: "A non-sense mutation at Arg-95 is predominant in complement 9 deficiency in Japanese" Journal of Immunology. 160. 1509-1513 (1998)

Horiuchi T：“Arg-95 处的无义突变在日本补体 9 缺乏症中占主导地位”《免疫学杂志》。

Higuchi M: "Membrane TNF-2 expressed on HTLV-I-infected T cells mediates a costimulatory signal for B cell activation" Clinical Immunology and Immunopathology. 82. 133-140 (1997)

Higuchi M：“HTLV-I 感染的 T 细胞上表达的膜 TNF-2 介导 B 细胞激活的共刺激信号”《临床免疫学和免疫病理学》。

Nishizaka H: "Molecular bases for inherited human complement component C6 deficiency in two unrelated individuals" J.Immunol.156. 2309-2315 (1996)

Nishizaka H：“两个无关个体遗传性人类补体成分 C6 缺乏的分子基础”J.Immunol.156。

Horiuchi T: "Identification of two novel mutations(1448delA and Q682X)in the NF1 gene and analysis for nonsense mutations in patients with neurofihrcmatosis 1" Human Mutation. Suppl.1. S47-49 (1998)

Horiuchi T：“NF1 基因中两种新突变（1448delA 和 Q682X）的鉴定以及神经纤维瘤病 1 患者无义突变的分析”人类突变。

Nishizaka H: "Genetic bases of human complement C7 deficieney" Journal of Immunology. 157. 4239-4243 (1996)

Nishizaka H：“人类补体 C7 缺陷的遗传基础”免疫学杂志。