Extensive normal copy number variation of a β-defensin antimicrobial-gene cluster
Extensive normal copy number variation of a β-defensin antimicrobial-gene cluster
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DOI：
10.1086/378157
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发表时间：
2003-09-01
影响因子：
9.8
通讯作者：
Barber, JCK
中科院分区：
文献类型：
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作者：
Hollox, EJ;Armour, JAL;Barber, JCK
使用多重可重复探针杂交和半定量荧光原位杂交（SQ-FISH）的组合，我们分析了染色体带8p23.1，一个经常参与染色体重排的区域的DNA拷贝数的变化。我们发现，至少有三个抗菌β-防御素基因（DEFB 4，DEFB 103，和DEFB 104）在8p23.1的集群是多态性的拷贝数，与大于或等于240 kb长的重复单位。每个二倍体基因组中有2 - 12个重复拷贝。通过分离，微卫星剂量，和SQ-FISH染色体信号强度比分析，我们推断，个别染色体可以有一个到八个拷贝的这个重复单位。具有七个或八个拷贝的该重复单元的染色体通过细胞遗传学分析可鉴定为先前描述的8p23.1常染色质变体。通过半定量逆转录聚合酶链反应分析来自不同个体的RNA显示DEFB 4的基因组拷贝数与其信使RNA（mRNA）转录水平之间存在显著相关性。由这些基因编码的肽是有效的抗微生物剂，特别是对临床上重要的病原体如铜绿假单胞菌和金黄色葡萄球菌有效，并且DEFB 4已被证明作为连接先天性和适应性免疫应答的细胞因子。因此，涉及这些基因的拷贝数多态性（反映在mRNA表达水平上）可能对免疫系统功能产生重要影响。
Using a combination of multiplex amplifiable probe hybridization and semiquantitative fluorescence in situ hybridization (SQ-FISH), we analyzed DNA copy number variation across chromosome band 8p23.1, a region that is frequently involved in chromosomal rearrangements. We show that a cluster of at least three antimicrobial beta-defensin genes (DEFB4, DEFB103, and DEFB104) at 8p23.1 are polymorphic in copy number, with a repeat unit greater than or equal to 240 kb long. Individuals have 2 - 12 copies of this repeat per diploid genome. By segregation, microsatellite dosage, and SQ-FISH chromosomal signal intensity ratio analyses, we deduce that individual chromosomes can have one to eight copies of this repeat unit. Chromosomes with seven or eight copies of this repeat unit are identifiable by cytogenetic analysis as a previously described 8p23.1 euchromatic variant. Analysis of RNA from different individuals by semiquantitative reverse-transcriptase polymerase chain reaction shows a significant correlation between genomic copy number of DEFB4 and levels of its messenger RNA ( mRNA) transcript. The peptides encoded by these genes are potent antimicrobial agents, especially effective against clinically important pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, and DEFB4 has been shown to act as a cytokine linking the innate and adaptive immune responses. Therefore, a copy number polymorphism involving these genes, which is reflected in mRNA expression levels, is likely to have important consequences for immune system function.