中国人C4重复基因座位初探

从78个家系266人次中研究了中国人C4基因的重复情况。在78个家系中有7个家系成员表现C4基因重复,占9.0%;依人头计,在266人中有17人C4基因表现重复,占6.4%。这17人均为C4B 基因重复,重复的类型及人数分别为,①C4B(1,2):2人,②B(1,12):6人;③B(1,1):5人;④B(1,96,96):2人;⑤B(2,2):2人。     

补体C4静息基因的结构基础及其与疾病的关系

补体C_4基因是补体遗传学研究的重要课题之一。现有资料表明C_4基因具有下列特征: 1.C_4基因位于人类第6号染色体短臂,与补体C2、Bf基因紧密连锁,共同组成HLA一Ⅲ类基因,居于HLA-Ⅰ、Ⅱ类基因之间。补体C_4由两个基因     

中国人C4Qo表型的C4DNA限制性片段长度多态现象：静息基因的机制初探

对１７例中国人Ｃ４Ａ／Ｃ４Ｂ表型中含有Ｑ０的个体的基因组ＤＮＡ进行了ＨｉｎｄⅢＲＦＬＰ的检测。从五型Ｃ４Ａ／Ｃ４Ｂ（３，０／１，１；３；０／２．１；３．３／１．０：３．２／１．０；３．０／１．０）中共检出５种ＲＦＬＰ片段组合Ａ：３２－２５－１５ｋｂ；Ｂ：３２－１５ｋｂ；Ｃ：２５－１５ｋｂ；Ｄ：３２－１５－８．５ｋｂ；Ｅ：２５－１５－８．５ｋｂ）。根据代表Ｃ４Ａ基因缺失的８．５ｋｂ片段的有无，测出大约５０％的Ｃ４ＡＱ０是由基因缺失造成的。此外，本文还对Ｃ４ＡＱ０时Ｃ４Ｂ长、短基因的分配，Ｃ４ＢＱ０时Ｃ４基因的变动情况等进行了分析与讨论。     

人类补体C4表型与C4A：C4B比值关系初探

用激光薄层密度扫描仪对171份血清补体 C4的电泳色带进行扫描,并求取其 C4A:C4B 比值(R 值)。结果发现含 C4A·QO 基因者的 R 值范围0.068～0.429,平均0.228,而含 C4B·QO 基因者的 R 值范围2.197～9.334,平均3.973;在所检出的7例具有 C4B·座位重复基因的样本中.其 R 值均很小(0.120～0.625),且其中含有 C4A·QO 者与不含 C4A·QO 者的 R 值有明显差异.结果表明根据 R 值大小来指定C4·QO 基因和重复基因是有一定道理的.在最常见的 C4表型3,3/1,1中,其 R 值呈常态分布,但表型3,3/2,1、3,3/2,2和3,2/1,1的 R 值多大于1.0,而表型4,4/2,2和4,4/2,1的 R 值多小于1.0。两组表型的 R 值之间的两两比较有显著性差异(P<0.01)。     

补体第四成分(C4)的基因

C4A3的基因由41个外显子与40个内含子组成。外显子1～16、16～33、33～41分别编磅码C4的β链、α链及γ链。唯一甘露糖型糖基化位点由第6外显子(207位aa)编码,三个两天线型糖基化部位分别与20(843aa)、30(1309aa)及32(1372aa)外显子有关。C4硫酯键、同种型区分部位及Rg/Ch抗原的基因集中在外显子23～30的C4d编码区。C4基因第9内含子特大,它含不含HERV-K(C4)是决定C4基因长与短的关键。C4基因的表达调控区没有TATA盒由Inr启动。     

乙型肝炎病毒在体内外抑制补体C3和C4表达的研究

目的 探讨乙型肝炎病毒(HBV)对补体C3和C4表达的影响,并探讨其调节机制.方法 采用基因芯片筛选HepG2和HepG2.2.15细胞的差异表达基因,免疫比浊法检测HBV患者和健康对照者补体C3和C4血清学水平,将HBV感染性克隆pHBV1.3转染HepG2细胞,RT-PCR和Western blot法检测C3和C4表达水平的变化.结果 补体C3和C4 mRNA在HepG2.2.15细胞中水平降低;C3和C4在慢性乙型肝炎患者和肝癌患者的血清学水平明显低于健康对照者(P＜0.05);HBV能够在mRNA和蛋白水平下调C3和C4的表达.结论 HBV能够在体内外抑制补体C3和C4的表达.     

中国广东法区汉族补体C4遗传多态性分析

采用国际补体参考实验方法，分析了广东地区３１９例无血缘关系汉族人Ｃ４多态性。共检出５个Ｃ４Ａ和８个Ｃ４Ｂ同种异型：Ｃ４Ａ５、４、３、２及Ｑ０及Ｃ４Ｂ５１４、２、１、９１、９６、９５、及Ｑ０。Ｃ４Ａ以Ａ＾＊３频率（０。６５３８）最高，Ａ＾＊Ｑ０（０．１３９４）及Ａ＾＊２（０．１３９４）及Ａ＾＊２（０．０４１７）次之。Ｃ４Ｂ以Ｂ＾＊２（０．４４０７）和Ｂ＾＊１（０．４１０３）最高，Ｂ＾＊Ｑ０（０．０９     

云南普米、傈僳、纳西、怒四个少数民族补体C4遗传多态性的检测

为了解人类补体成份Ｃ４遗传多态性，用神经氨酸酶和羧肽酶Ｂ处理ＥＤＴＡ抗凝血浆，继以琼脂糖高压电泳、免疫固定及薄层激光密度扫描等技术对云南普米、傈僳、纳西和怒４个少数民族进行补体Ｃ４遗传多态性的检测，并与湖北汉族进行对比。结果显示：５个民族的Ｃ４Ａ／Ｃ４Ｂ表型分布不完全相同。在基因频率方面：Ｃ４Ａ除普米族以Ｃ４Ｑ０最高外，其余均以Ｃ４Ａ３为高；Ｃ４Ｂ在５个民族中都以Ｃ４Ｂ１最高，其余参差不等。湖北汉族与４个少数民族之间的差异主要表现在Ｃ４Ａ２，Ｃ４Ａ３，Ｃ４Ａ５和Ｃ４Ｂ２２；４个少数民族之间同样存在较大差异，普米族与其他３个少数民族的差异最为显著，其次是傈僳族，纳西族和怒族之间的差异不显著。     

Evolutionary analysis of two complement C4 genes: Ancient duplication and conservation during jawed vertebrate evolution

The complement C4 is a thioester-containing protein, and a histidine (H) residue catalyzes the cleavage of the thioester to allow covalent binding to carbohydrates on target cells. Some mammalian and teleost species possess an additional isotype where the catalytic H is replaced by an aspartic acid (D), which binds preferentially to proteins. We found the two C4 isotypes in many other jawed vertebrates, including sharks and birds/reptiles. Phylogenetic analysis suggested that C4 gene duplication occurred in the early days of the jawed vertebrate evolution. The D-type C4 of bony fish except for mammals formed a cluster, termed D-lineage. The D-lineage genes were located in a syntenic region outside MHC, and evolved conservatively. Mammals lost the D-lineage before speciation, but D-type C4 was regenerated by recent gene duplication in some mammalian species or groups. Dual C4 molecules with different substrate specificities would have contributed to development of the antibody-dependent classical pathway.     

我国藏族人群补体第四成分单倍型的分布分析

采用武汉同济医科大学中澳友谊补体实验室仿国际标准Ｃ４定型程序改进后建立的方法，对９９名无血缘关系的藏族人进行补体Ｃ４单倍型检测。对１９８个Ｃ４单倍型检测结果分析，我国藏族人群Ｃ４单倍型频率以Ａ３Ｂ１最高（０．４１９２），Ａ３Ｂ２次之（０．１８６８），以下依次是：Ａ４Ｂ２（０．０７０７）、Ａ２Ｂ１（０．０７０７）、Ａ３Ｂ５（０．０４５４）等。在Ｃ４Ａ座位上发现８个型别：Ｃ４Ａ５、４、３、２、１、３４     

Familial C4B deficiency and immune complex glomerulonephritis

Homozygous complement C4B deficiency is described in a Southern European young female patient with Membranoproliferative Glomerulonephritis (MPGN) type III characterized by renal biopsies with strong complement C4 and IgG deposits. Low C4 levels were independent of clinical evolution or type of immunosuppression and were found in three other family members without renal disease or infections. HLA typing revealed that the patient has homozygous A*02, Cw*06, B*50 at the class I region, and DRB1*08 and DQB1*03 at the class II region. Genotypic and phenotypic studies demonstrated that the patient has homozygous monomodular RCCX in the HLA class III region, with single long C4A genes coding for C4A3 and complete C4B deficiency. Her father, mother, son and niece have heterozygous C4B deficiency. The patient's deceased brother had a history of Henoch–Schönlein Purpura (HSP), an immune complex-mediated proliferative glomerulonephritis. These findings challenge the putative pathophysiological roles of C4A and C4B and underscore the need to perform functional assays, C4 allotyping and genotyping on patients with persistently low serum levels of a classical pathway complement component and glomerulopathy associated with immune deposits.     

血清超敏C反应蛋白、转铁蛋白、补体C3和C4在儿童全身炎性反应综合征中的临床价值

目的 探讨全身炎性反应综合征(SIRS)患儿血清超敏C反应蛋白(hs-CRP)、转铁蛋白(TRf)和补体C3、C4水平的变化及意义.方法 2012年7月至2013年6月本院PICU、NICU和急诊综合病区符合SIRS诊断的患儿93例(SIRS组),对照组为年龄、性别与患儿相匹配的健康体检儿童65例,测定两组儿童血清中hs-CRP、TRf、补体C3和C4的水平.对93例患儿进行SIRS评分,根据评分分成A组(SIRS 2分)37例、B组(SIRS 3分)32例、C组(SIRS 4分)24例,比较3组血清中hs-CRP、TRf、补体C3和C4的水平并统计病死率,与SIRS评分进行相关分析.结果 SIRS组患儿血清hs-CRP水平高于对照组[(33.85±17.76)mg/L比(2.34±1.54) mg/L,P＜0.05].SIRS组血清TRf、补体C3和C4的水平均低于对照组[血清TRf:(1.26±0.48)g/L比(2.81±0.57)g/L,补体C3:(0.48±0.19)g/L比(1.14±0.21)g/L,补体C4:(0.19±0.09)g/L比(0.39±0.10)g/L,均P＜0.05].SIRS患儿血清hs-CRP水平随SIRS评分升高而升高,呈正相关(r=0.863,P＜0.05),血清TRf、补体C3和C4的水平则随SIRS评分的升高而降低,呈负相关(r=-0.834、-0.715、-0.691,均P＜0.05).病死率也随SIRS评分的升高而逐渐升高,呈正相关(r=1.00,P＜0.05).结论 血清中hs-CRP、TRf、补体C3和C4的水平对评估SIRS患儿的病情和预后有重要意义.     

Combined Heterozygous Deficiency of the Classical Complement Pathway Proteins C2 and C4

Genetic deficiencies of components of the classical pathway of complement activation are associated with an increased risk for the development of autoimmune and immune complex-mediated diseases. In the present study we report on the molecular and clinical features associated with combined heterozygous C4 and C2 deficiency in 15 individuals investigated within six families. Approximately 30% of the individuals manifested SLE or another autoimmune condition. Heterozygous C2 deficiency was related to a 28-bp deletion in the C2 gene (C2 deficiency type I), in most cases within the HLA-A25 B18 C2Q0 BfS C4A4B2 DR2 haplotype. Among 13 partial C4-deficient haplotypes transmitted, 8 carried C4A*Q0 alleles and 5 C4B*Q0 alleles. In seven cases the C4A*Q0 alleles were associated with a deletion of the C4A/CYP21P genes within the HLA-B8 C2C BfS C4AQ0B1 DR3 haplotype. In three cases, the C4B*Q0 allele was associated with a deletion of the C4B/CYP21P genes within the HLA-B18 C2C BfF1 C4A3BQ0 DR3 haplotype. In the other cases, C4A*Q0 or C4B*Q0 was dependent on as yet uncharacterized defects in the C4 gene or in C4 gene expression. In view of the relatively high frequency of heterozygous C4 deficiency in the normal Caucasian population, the expected frequency of the combined deficiency should approximate 0.001.     

Stringent regulation of complement lectin pathway C3/C5 convertase by C4b-binding protein (C4BP)

The complement lectin pathway, an essential component of the innate immune system, is geared for rapid recognition of infections as each C4b deposited via this pathway is capable of forming a C3/C5 convertase. In the present study, role of C4b-binding protein (C4BP) in regulating the lectin pathway C3/C5 convertase assembled on zymosan and sheep erythrocytes coated with mannan (E_Man) was examined. While the C4BP concentration for inhibiting 50% (IC₅₀) formation of surface-bound C3 convertase on the two surfaces was similar to that obtained for the soluble C3 convertase (1.05 nM), 3- and 41-fold more was required to inhibit assembly of the C5 convertase on zymosan (2.81 nM) and E_Man (42.66 nM). No difference in binding interactions between C4BP and surface-bound C4b alone or in complex with C3b was observed. Increasing the C4b density on zymosan (14,000–431,000 C4b/Zym) increased the number of C4b bound per C4BP from 2.87 to 8.23 indicating that at high C4b density all seven α-chains of C4BP are engaged in C4b-binding. In contrast, the number of C4b bound per C4BP remained constant (3.79 ± 0.60) when the C4b density on E_Man was increased. The data also show that C4BP regulates assembly and decay of the lectin pathway C3/C5 convertase more stringently than the classical pathway C3/C5 convertase because of a 7- to 13-fold greater affinity for C4b deposited via the lectin pathway than the classical pathway. C4BP thus regulates efficiently the four times greater potential of the lectin pathway than the classical pathway in generating the C3/C5 convertase and hence production of pro-inflammatory products, which are required to fight infections but occasionally cause pathological inflammatory reactions.     

The covalent binding story of the complement proteins C3 and C4 (I) 1972-1981

Alex Law and Paul Levine recall their work to establish the covalent bond between C3 and target surfaces. It started with a naive experiment by analyzing the membrane polypeptides of sheep erythrocytes bound with ¹²⁵I-labelled C3. They found complexes with molecular weight higher than the individual C3 polypeptides. These complexes survived all conditions designed to disrupt non-covalent interactions. They then showed that the bond was an ester, with an active acyl group on C3 which reacted with a hydroxyl group on the acceptor molecule. With the discovery of an internal thioester by Jim Prahl, Jamila Janatova, Brian Tack and their colleagues, it became clear that the reaction was by an acyl transfer from the thioester of C3 to the target hydroxyl group. Later on they showed that C4 also bound covalently to target molecules. By establishing a fluid phase system to study the kinetics of the binding reactions of C3 and C4, Alex was able to continue the work in the MRC Immunochemistry Unit in Oxford from 1981, to eventually determine the chemical mechanism of the binding reaction. In order to give some sense of reality, this article is written as a narrative from Alex, who did the experiments.Both Alex and Paul are retired. Pauls lives on Martha’s Vineyard where he writes occasional articles on science for one of the Island's newspapers. Alex lives in Hong Kong and tries to make some sense of the local politics.