Jia H P, Schutte B C, Schudy A, Linzmeier R, Guthmiller J M, Johnson G K, Tack B F, Mitros J P, Rosenthal A, Ganz T, McCray P B
Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
Gene. 2001 Jan 24;263(1-2):211-8. doi: 10.1016/s0378-1119(00)00569-2.
Epithelial beta-defensins are broad-spectrum cationic antimicrobial peptides that also act as chemokines for adaptive immune cells. In the human genome, all known defensin genes cluster to a <1 Mb region of chromosome 8p22-p23. To identify new defensin genes, the DNA sequence from a contig of large-insert genomic clones from the region containing human beta-defensin-2 (HBD-2) was analyzed for the presence of defensin genes. This sequence survey identified a novel beta-defensin, termed HBD-3. The HBD-3 gene contains two exons, is located 13 kb upstream from the HBD-2 gene, and it is transcribed in the same direction. A partial HBD-3 cDNA clone was amplified from cDNA derived from IL-1beta induced fetal lung tissue. The cDNA sequence encodes for a 67 amino acid peptide that is approximately 43% identical to HBD-2 and shares the beta-defensin six cysteine motif. By PCR analysis of two commercial cDNA panels, HBD-3 expression was detected in adult heart, skeletal muscle, placenta and in fetal thymus. From RT-PCR experiments, HBD-3 expression was observed in skin, esophagus, gingival keratinocytes, placenta and trachea. Furthermore, in fetal lung explants and gingival keratinocytes, HBD-3 mRNA expression was induced by IL-1beta. Additional sequence analysis identified the HE2 (human epididymis secretory protein) gene 17 kb upstream from the HBD-3 gene. One splice variant of this gene (HE2beta1) encodes a beta-defensin consensus cysteine motif, suggesting it represents a defensin gene product. HE2beta1 mRNA expression was detected in gingival keratinocytes and bronchial epithelia using RT-PCR analysis. The discovery of these novel beta-defensin genes may allow further understanding of the role of defensins in host immunity at mucosal surfaces.
上皮β-防御素是广谱阳离子抗菌肽，同时也是适应性免疫细胞的趋化因子。在人类基因组中，所有已知的防御素基因聚集在8号染色体p22 - p23的一个小于1 Mb的区域。为了鉴定新的防御素基因，对来自包含人β-防御素-2（HBD-2）区域的大插入基因组克隆重叠群的DNA序列进行分析，以寻找防御素基因。该序列调查鉴定出一种新型β-防御素，命名为HBD-3。HBD-3基因包含两个外显子，位于HBD-2基因上游13 kb处，且转录方向相同。从白细胞介素-1β诱导的胎儿肺组织衍生的cDNA中扩增出一个部分HBD-3 cDNA克隆。该cDNA序列编码一个67个氨基酸的肽，与HBD-2的同源性约为43%，并具有β-防御素的六个半胱氨酸基序。通过对两个商业cDNA文库的PCR分析，在成人心脏、骨骼肌、胎盘和胎儿胸腺中检测到HBD-3表达。从逆转录聚合酶链反应（RT-PCR）实验中，在皮肤、食管、牙龈角质形成细胞、胎盘和气管中观察到HBD-3表达。此外，在胎儿肺外植体和牙龈角质形成细胞中，白细胞介素-1β可诱导HBD-3 mRNA表达。进一步的序列分析在HBD-3基因上游17 kb处鉴定出HE2（人类附睾分泌蛋白）基因。该基因的一个剪接变体（HE2β1）编码一个β-防御素共有半胱氨酸基序，表明它代表一种防御素基因产物。使用RT-PCR分析在牙龈角质形成细胞和支气管上皮中检测到HE2β1 mRNA表达。这些新型β-防御素基因的发现可能有助于进一步了解防御素在黏膜表面宿主免疫中的作用。
