Østergaard Anders E, Martin Samuel A M, Wang Tiehui, Stet René J M, Secombes Christopher J
Scottish Fish Immunology Research Centre, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, Scotland, UK.
Dev Comp Immunol. 2009 Apr;33(4):525-32. doi: 10.1016/j.dci.2008.10.002. Epub 2008 Nov 12.
The recognition of pathogens by the innate immune system relies on a wide range of inhibitory and activating receptors. Some of these non-rearranging receptors belong to the immunoglobulin superfamily (IgSF) and in teleost fish the novel immune-type receptor (NITR) and the novel immunoglobulin-like transcript (NILT) have been reported. Here we describe the identification and characterisation of three new NILTs from rainbow trout (Oncorhynchus mykiss), with one NILT alternatively spliced into a long isoform containing two Ig domains and a short isoform containing one Ig domain. The cytoplasmic regions contain either immunoreceptor tyrosine-based inhibitory motifs (ITIMs) or an immunoreceptor tyrosine-based activating motif (ITAM) for downstream signalling. Alignment of the various NILT Ig domains revealed a high similarity, especially between Ig domains from NILTs found in this study. Furthermore, a phylogenetic tree showed that NILTs are more closely related to the triggering receptor expressed on myeloid (TREM) cells and NKp44 than to NITRs. The expression of NILTs was studied in six different tissues and two different cell lines, with expression apparent in immunologically important tissues. Expression of NILTs was also shown to be an early event in development, with both eyed eggs and embryos expressing all four genes. The results obtained in this study and future experiments will contribute to our knowledge of the immune system in fish and provide useful information for the control of inflammatory processes in rainbow trout.
天然免疫系统对病原体的识别依赖于多种抑制性和激活性受体。其中一些非重排受体属于免疫球蛋白超家族（IgSF），在硬骨鱼中已报道了新型免疫型受体（NITR）和新型免疫球蛋白样转录本（NILT）。在此，我们描述了虹鳟（Oncorhynchus mykiss）中三个新的NILT的鉴定和特征，其中一个NILT可选择性剪接成长异构体，包含两个Ig结构域，以及短异构体，包含一个Ig结构域。细胞质区域含有基于免疫受体酪氨酸的抑制基序（ITIM）或基于免疫受体酪氨酸的激活基序（ITAM）用于下游信号传导。各种NILT Ig结构域的比对显示出高度相似性，特别是在本研究中发现的NILT的Ig结构域之间。此外，系统发育树表明，NILT与髓样细胞表达的触发受体（TREM）和NKp44的关系比与NITR的关系更密切。在六种不同组织和两种不同细胞系中研究了NILT的表达，在免疫重要组织中明显有表达。NILT的表达也被证明是发育中的早期事件，有眼卵和胚胎均表达所有四个基因。本研究及未来实验所得结果将有助于我们了解鱼类免疫系统，并为控制虹鳟的炎症过程提供有用信息。
