Rodriguez-Nunez Ivan, Wcisel Dustin J, Litman Ronda T, Litman Gary W, Yoder Jeffrey A
Department of Molecular Biomedical Sciences and Center for Comparative Medicine and Translational Research, North Carolina State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA.
Department of Pediatrics, University of South Florida Morsani College of Medicine, USF/ACH Children's Research Institute, 140 7th Avenue South, St. Petersburg, FL, 33701, USA.
Immunogenetics. 2016 Apr;68(4):295-312. doi: 10.1007/s00251-016-0901-6. Epub 2016 Jan 22.
Bony fish encode multiple multi-gene families of membrane receptors that are comprised of immunoglobulin (Ig) domains and are predicted to function in innate immunity. One of these families, the diverse immunoglobulin (Ig) domain-containing protein (DICP) genes, maps to three chromosomal loci in zebrafish. Most DICPs possess one or two Ig ectodomains and include membrane-bound and secreted forms. Membrane-bound DICPs include putative inhibitory and activating receptors. Recombinant DICP Ig domains bind lipids with varying specificity, a characteristic shared with mammalian CD300 and TREM family members. Numerous DICP transcripts amplified from different lines of zebrafish did not match the zebrafish reference genome sequence suggesting polymorphic and haplotypic variation. The expression of DICPs in three different lines of zebrafish has been characterized employing PCR-based strategies. Certain DICPs exhibit restricted expression in adult tissues whereas others are expressed ubiquitously. Transcripts of a subset of DICPs can be detected during embryonic development suggesting roles in embryonic immunity or other developmental processes. Transcripts representing 11 previously uncharacterized DICP sequences were identified. The assignment of two of these sequences to an unplaced genomic scaffold resulted in the identification of an alternative DICP haplotype that is linked to a MHC class I Z lineage haplotype on zebrafish chromosome 3. The linkage of DICP and MHC class I genes also is observable in the genomes of the related grass carp (Ctenopharyngodon idellus) and common carp (Cyprinus carpio) suggesting that this is a shared character with the last common Cyprinidae ancestor.
硬骨鱼编码多个由免疫球蛋白（Ig）结构域组成的膜受体多基因家族，预计其在先天免疫中发挥作用。其中一个家族，即含有多种免疫球蛋白（Ig）结构域的蛋白质（DICP）基因，定位于斑马鱼的三个染色体位点。大多数DICP具有一个或两个Ig胞外结构域，包括膜结合形式和分泌形式。膜结合DICP包括假定的抑制性和激活性受体。重组DICP Ig结构域以不同的特异性结合脂质，这是与哺乳动物CD300和TREM家族成员共有的特征。从不同品系斑马鱼中扩增出的许多DICP转录本与斑马鱼参考基因组序列不匹配，表明存在多态性和单倍型变异。已采用基于PCR的策略对三种不同品系斑马鱼中DICP的表达进行了表征。某些DICP在成体组织中表达受限，而其他的则普遍表达。在胚胎发育过程中可以检测到一部分DICP的转录本，表明其在胚胎免疫或其他发育过程中发挥作用。鉴定出了代表11个先前未表征的DICP序列的转录本。将其中两个序列定位到一个未定位的基因组支架上，从而鉴定出一种与斑马鱼3号染色体上的MHC I类Z谱系单倍型相关的替代DICP单倍型。在相关草鱼（Ctenopharyngodon idellus）和鲤鱼（Cyprinus carpio）的基因组中也可以观察到DICP与MHC I类基因的连锁，这表明这是鲤科最后一个共同祖先的共同特征。
