TY - JOUR
T1 - A third broad lineage of major histocompatibility complex (MHC) class I in teleost fish; MHC class II linkage and processed genes
AU - Dijkstra, Johannes Martinus
AU - Katagiri, Takayuki
AU - Hosomichi, Kazuyoshi
AU - Yanagiya, Kazuyo
AU - Inoko, Hidetoshi
AU - Ototake, Mitsuru
AU - Aoki, Takashi
AU - Hashimoto, Keiichiro
AU - Shiina, Takashi
PY - 2007/4/1
Y1 - 2007/4/1
N2 - Most of the previously studied teleost MHC class I molecules can be classified into two broad lineages: "U" and "Z/ZE." However, database reports on genes in cyprinid and salmonid fishes show that there is a third major lineage, which lacks detailed analysis so far. We designated this lineage "L" because of an intriguing linkage characteristic. Namely, one zebrafish L locus is closely linked with MHC class II loci, despite the extensively documented nonlinkage of teleost class I with class II. The L lineage consists of highly variable, nonclassical MHC class I genes, and has no apparent orthologues outside teleost fishes. Characteristics that distinguish the L lineage from most other MHC class I are (1) absence of two otherwise highly conserved tryptophan residues W51 and W60 in the α1 domain, (2) a low GC content of the α1 and α2 exons, and (3) an HINLTL motif including a possible glycosylation site in the α3 domain. In rainbow trout (Oncorhynchus mykiss) we analyzed several intact L genes in detail, including their genomic organization and transcription pattern. The gene Onmy-LAA is quite different from the genes Onmy-LBA, Onmy-LCA, Onmy-LDA, and Onmy-LEA, while the latter four are similar and categorized as "Onmy-LBA-like." Whereas the Onmy-LAA gene is organized like a canonical MHC class I gene, the Onmy-LBA-like genes are processed and lack all introns except intron 1. Onmy-LAA is predominantly expressed in the intestine, while the Onmy-LBA-like transcripts display a rather homogeneous tissue distribution. To our knowledge, this is the first description of an MHC class I lineage with multiple copies of processed genes, which are intact and transcribed. The present study significantly improves the knowledge of MHC class I variation in teleosts.
AB - Most of the previously studied teleost MHC class I molecules can be classified into two broad lineages: "U" and "Z/ZE." However, database reports on genes in cyprinid and salmonid fishes show that there is a third major lineage, which lacks detailed analysis so far. We designated this lineage "L" because of an intriguing linkage characteristic. Namely, one zebrafish L locus is closely linked with MHC class II loci, despite the extensively documented nonlinkage of teleost class I with class II. The L lineage consists of highly variable, nonclassical MHC class I genes, and has no apparent orthologues outside teleost fishes. Characteristics that distinguish the L lineage from most other MHC class I are (1) absence of two otherwise highly conserved tryptophan residues W51 and W60 in the α1 domain, (2) a low GC content of the α1 and α2 exons, and (3) an HINLTL motif including a possible glycosylation site in the α3 domain. In rainbow trout (Oncorhynchus mykiss) we analyzed several intact L genes in detail, including their genomic organization and transcription pattern. The gene Onmy-LAA is quite different from the genes Onmy-LBA, Onmy-LCA, Onmy-LDA, and Onmy-LEA, while the latter four are similar and categorized as "Onmy-LBA-like." Whereas the Onmy-LAA gene is organized like a canonical MHC class I gene, the Onmy-LBA-like genes are processed and lack all introns except intron 1. Onmy-LAA is predominantly expressed in the intestine, while the Onmy-LBA-like transcripts display a rather homogeneous tissue distribution. To our knowledge, this is the first description of an MHC class I lineage with multiple copies of processed genes, which are intact and transcribed. The present study significantly improves the knowledge of MHC class I variation in teleosts.
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U2 - 10.1007/s00251-007-0198-6
DO - 10.1007/s00251-007-0198-6
M3 - Article
C2 - 17318646
AN - SCOPUS:33847771291
VL - 59
SP - 305
EP - 321
JO - Immunogenetics
JF - Immunogenetics
SN - 0093-7711
IS - 4
ER -