Research Unit of Immunology and Microbiology, Institute of Medical Biology, Faculty of Health Science, University of Southern Denmark, Odense, Denmark.
Dev Comp Immunol. 2010 Jan;34(1):59-68. doi: 10.1016/j.dci.2009.08.004. Epub 2009 Aug 29.
The lectin complement pathway has important functions in vertebrate host defence and accumulating evidence of primordial complement components trace its emergence to invertebrate phyla. We introduce two putative mannose-binding lectin homologues (CioMBLs) from the urochordate species Ciona intestinalis. The CioMBLs display similarities with vertebrate MBLs and comprise a collagen-like region, alpha-helical coiled-coils and a carbohydrate recognition domain (CRD) with conserved residues involved in calcium and carbohydrate binding. Structural analysis revealed an oligomerization through interchain disulphide bridges between N-terminal cysteine residues and cysteines located between the neck region and the CRD. RT-PCR showed a tissue specific expression of CioMBL in the gut and by immunohistochemistry analysis we also demonstrated that CioMBL co-localize with an MBL-associated serine protease in the epithelia cells lining the stomach and intestine. In conclusion we present two urochordate MBLs and identify an associated serine protease, which support the concept of an evolutionary ancient origin of the lectin complement pathway.
凝集素补体途径在脊椎动物宿主防御中具有重要功能，越来越多的原始补体成分的证据表明其起源于无脊椎动物门。我们从尾索动物物种文昌鱼（Ciona intestinalis）中引入了两种假定的甘露糖结合凝集素同源物（CioMBLs）。CioMBLs 与脊椎动物 MBLs 具有相似性，包括胶原样区域、α-螺旋卷曲螺旋和碳水化合物识别结构域（CRD），其中保守残基参与钙和碳水化合物的结合。结构分析显示通过 N 端半胱氨酸残基和位于颈部区域和 CRD 之间的半胱氨酸之间的链间二硫键发生寡聚化。RT-PCR 显示 CioMBL 在肠道中的组织特异性表达，通过免疫组织化学分析，我们还证明 CioMBL 与胃和肠上皮细胞 lining 中的 MBL 相关丝氨酸蛋白酶共定位。总之，我们提出了两种尾索动物 MBLs，并鉴定了一种相关的丝氨酸蛋白酶，这支持了凝集素补体途径具有古老的进化起源的概念。
