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首页> 外文期刊>Infection and immunity >Enteric β-Defensin: Molecular Cloning and Characterization of a Gene with Inducible Intestinal Epithelial Cell Expression Associated with Cryptosporidium parvumInfection
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Enteric β-Defensin: Molecular Cloning and Characterization of a Gene with Inducible Intestinal Epithelial Cell Expression Associated with Cryptosporidium parvumInfection

机译：肠道β-防御素：与小隐孢子虫感染相关的可诱导肠上皮细胞表达基因的分子克隆和表征

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A growing body of evidence suggests that endogenous antibiotics contribute to the innate defense of mammalian mucosal surfaces. In the cow, β-defensins constitute a large family of antibiotic peptides whose members have been previously isolated from the respiratory and oral mucosa, as well as circulating phagocytic cells. A novel bovine genomic clone with sequence related to those of these α-defensins was isolated and characterized. The corresponding cDNA was isolated from a small intestinal library; its open reading frame predicts a deduced sequence of a novel β-defensin, which we designate enteric β-defensin (EBD). Northern blot analysis of a variety of bovine tissues revealed that EBD mRNA is highly expressed in the distal small intestine and colon, anatomic locations distinct from those for previously characterized β-defensins. EBD mRNA was further localized by in situ hybridization to epithelial cells of the colon and small intestinal crypts. Infection of two calves with the intestinal parasiteCryptosporidium parvum induced 5- and 10-fold increases above control levels of EBD mRNA in intestinal tissues. An anchored-PCR strategy was used to identify other β-defensin mRNAs expressed in the intestine. In addition to that of EBD, several low-abundance cDNAs which corresponded to other β-defensin mRNAs were cloned. Most of these clones encoded previously characterized β-defensins or closely related isoforms, but two encoded a previously uncharacterized prepro-β-defensin. Northern blot evidence supported that all of these other β-defensin genes are expressed at levels lower than that of the EBD gene in enteric tissue. Furthermore, some of these β-defensin mRNAs were abundant in bone marrow, suggesting that in enteric tissue their expression may be in cells of hematopoietic origin. Extracts of small intestinal mucosa obtained from healthy cows have numerous active chromatographic fractions as determined by an antibacterial assay, and one peptide was partially purified. The peptide corresponded to one of the low-abundance cDNAs. This study provides evidence of β-defensin expression in enteric tissue and that the mRNA encoding a major β-defensin of enteric tissue, EBD, is inducibly expressed in enteric epithelial cells. These findings support the proposal that β-defensins may contribute to host defense of enteric mucosa.
机译：越来越多的证据表明，内源性抗生素有助于哺乳动物粘膜表面的先天防御。在牛中，β-防御素构成了一个很大的抗生素肽家族，其成员先前已从呼吸道和口腔粘膜以及循环吞噬细胞中分离出来。分离并鉴定了具有与这些α-防御素的序列相关的序列的新型牛基因组克隆。从小肠文库中分离出相应的cDNA。它的开放阅读框预测了新的β-防御素的推导序列，我们将其命名为肠道β-防御素（EBD）。对各种牛组织的Northern印迹分析表明，EBD mRNA在远端小肠和结肠中高表达，其解剖位置不同于先前表征的β-防御素。 EBD mRNA通过原位杂交进一步定位到结肠和小肠隐窝的上皮细胞。肠道寄生虫 Cryptosporidium parvum 感染两只小牛后，肠组织中EBD mRNA的表达水平比对照水平高出5倍和10倍。锚定PCR策略用于鉴定肠中表达的其他β-防御素mRNA。除EBD以外，还克隆了一些与其他β-防御素mRNA相对应的低丰度cDNA。这些克隆中的大多数编码以前表征的β-防御素或密切相关的同工型，但其中两个编码以前未表征的prepro-β-防御素。 Northern blot证据支持所有其他β-防御素基因在肠组织中的表达水平低于EBD基因。此外，这些β-防御素mRNA中的一些在骨髓中丰富，这表明它们在肠组织中的表达可能在造血来源的细胞中。从健康的奶牛获得的小肠粘膜提取物具有许多活性色谱级分（通过抗菌测定确定），并且一种肽已部分纯化。该肽对应于低丰度cDNA之一。该研究提供了在肠组织中β-防御素表达的证据，并且在肠上皮细胞中可诱导表达编码肠组织主要β-防御素的EBD的mRNA。这些发现支持了β-防御素可能有助于宿主肠粘膜防御的提议。

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