Evaluation of the expression of the neutrophil antibacterial defensin genes

点击翻译按钮获取中文摘要

Neutrophils contain the antimicrobial defensins (cationic peptides) in the granules. IN this study, to understand the defensin gene expression, cDNA and gene clones for defensins were isolated and analyzed. Furthermore, the expression of defensin gene was evaluated in various types of leukocytes using in situ hybridization.Three kinds of cDNAs were isolated from a cDNA library, and sequence analysis revealed that these cDNAs were highly homologous (99%), and that two encoded defensin-1 and one encoded defensin-2, suggesting that defensin-1/-2 are encoded by the similar but different genes. Consistent with this, four different clones for defensin genes (two representing the alleles of defensin01 gene, and other two representing the alleles of defensin-2 gene) were isolated from a genomic library. Transfection analysis demonstrated that the promoters were located within 400 bp upstream of the transcription start sites of both genes, and that the promotor activity of defensin-1 was 2-fold higher than that of defensin-2 gene. In situ hybridization demonstrated that defensin mRNA was expressed in the neutorophil precursor cells, such as promyelocytes and myelocytes, but waas not detected in mature neutrophils, monocytes, macrophages, eosinophils and lymphocytes. Together these observations indicate that defensins are encoded by the similar but different genes, and that the expression of the defensin genes are likely regulated during a limited period of neutrophil maturation at the level of transcription in the bone marrow.