Bao Baolong, Peatman Eric, Li Ping, He Chongbo, Liu Zhanjiang
The Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA.
Dev Comp Immunol. 2005;29(11):939-50. doi: 10.1016/j.dci.2005.03.006.
Antimicrobial peptides (AMPs) are important components of the host innate immune response against microbial invasion. The cysteine-rich AMPs such as defensin and hepcidin have been extensively studied from various organisms, but their role in disease defense in catfish is unknown. As a first step, we sequenced a hepcidin cDNA from both channel catfish and blue catfish, and characterized the channel catfish hepcidin gene. The channel catfish hepcidin gene consists of two introns and three exons that encode a peptide of 96 amino acids. The amino acid sequences and gene organization were conserved between catfish and other organisms. In contrast to its almost exclusive expression in the liver in humans, the channel catfish hepcidin gene was expressed in a wide range of tissues except brain. Its expression was detected early during embryonic and larval development, and induced after bacterial infection with Edwardsiella ictaluri, the causative agent of enteric septicemia of catfish (ESC) in a tissue-specific manner. The upregulation was observed in the spleen and head kidney, but not in the liver. The expression of hepcidin was upregulated 1--3 days after challenge, but returned to normal levels at 7 days after challenge. The expression profile of the catfish hepcidin gene during the course of bacterial infection mirrors those of inflammatory proteins such as chemokines, suggesting an important role for hepcidin during inflammatory responses.
抗菌肽（AMPs）是宿主针对微生物入侵的固有免疫反应的重要组成部分。富含半胱氨酸的抗菌肽，如防御素和铁调素，已在各种生物体中得到广泛研究，但它们在鲶鱼疾病防御中的作用尚不清楚。作为第一步，我们对斑点叉尾鮰和蓝鲶的铁调素cDNA进行了测序，并对斑点叉尾鮰铁调素基因进行了表征。斑点叉尾鮰铁调素基因由两个内含子和三个外显子组成，编码一个96个氨基酸的肽段。鲶鱼与其他生物体之间的氨基酸序列和基因结构是保守的。与人类几乎只在肝脏中表达不同，斑点叉尾鮰铁调素基因在除脑以外的广泛组织中表达。在胚胎和幼体发育早期就检测到其表达，并在感染鮰爱德华氏菌（鲶鱼肠败血症（ESC）的病原体）后以组织特异性方式诱导表达。在脾脏和头肾中观察到上调，但在肝脏中未观察到。铁调素的表达在攻击后1 - 3天上调，但在攻击后7天恢复到正常水平。鲶鱼铁调素基因在细菌感染过程中的表达谱与趋化因子等炎症蛋白的表达谱相似，表明铁调素在炎症反应中起重要作用。
