A first map of the porcine major histocompatibility complex class I region

Velten, Florian; Rogel–Gaillard, Claire; Renard, Christine; Pontarotti, Pierre; Tazi-Ahnini, Rachid; Vaiman, M.; Chardon, Patrick

doi:10.1111/j.1399-0039.1998.tb02963.x

Cited by 29 publications

(2 citation statements)

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“…The subdivision of MHC-I genes into classical, highly polymorphic genes that present peptides to T-cells, and non-classical genes, less polymorphic genes that do not present peptides to T-cells, have been reported in many mammal species and also in several bird species [3–5, 10, 11, 19–21, 27–30]. However, classical and non-classical genes have not yet been confirmed in songbirds in the largest bird order Passeriformes, though such subdivision is likely since non-classical genes have been identified in other bird species from several different orders [25–30].…”

Section: Discussionmentioning

confidence: 99%

“…In most species studied to date — for example humans and other primates, swine, mice and chicken — MHC-I genes are categorized as classical or non-classical MHC-I genes [3, 5, 10, 11]. In mammals, classical MHC-I genes (MHC-Ia) are highly polymorphic and highly expressed, whereas non-classical (MHC-Ib) are less polymorphic and have low expression [12, 13].…”

Section: Introductionmentioning

confidence: 99%

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Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

et al. 2017

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BackgroundThe Major Histocompatibility Complex (MHC) plays a central role in immunity and has been given considerable attention by evolutionary ecologists due to its associations with fitness-related traits. Songbirds have unusually high numbers of MHC class I (MHC-I) genes, but it is not known whether all are expressed and equally important for immune function. Classical MHC-I genes are highly expressed, polymorphic and present peptides to T-cells whereas non-classical MHC-I genes have lower expression, are more monomorphic and do not present peptides to T-cells. To get a better understanding of the highly duplicated MHC genes in songbirds, we studied gene expression in a phylogenetic framework in three species of sparrows (house sparrow, tree sparrow and Spanish sparrow), using high-throughput sequencing. We hypothesize that sparrows could have classical and non-classical genes, as previously indicated though never tested using gene expression.ResultsThe phylogenetic analyses reveal two distinct types of MHC-I alleles among the three sparrow species, one with high and one with low level of polymorphism, thus resembling classical and non-classical genes, respectively. All individuals had both types of alleles, but there was copy number variation both within and among the sparrow species. However, the number of highly polymorphic alleles that were expressed did not vary between species, suggesting that the structural genomic variation is counterbalanced by conserved gene expression. Overall, 50% of the MHC-I alleles were expressed in sparrows. Expression of the highly polymorphic alleles was very variable, whereas the alleles with low polymorphism had uniformly low expression. Interestingly, within an individual only one or two alleles from the polymorphic genes were highly expressed, indicating that only a single copy of these is highly expressed.ConclusionsTaken together, the phylogenetic reconstruction and the analyses of expression suggest that sparrows have both classical and non-classical MHC-I genes, and that the evolutionary origin of these genes predate the split of the three investigated sparrow species 7 million years ago. Because only the classical MHC-I genes are involved in antigen presentation, the function of different MHC-I genes should be considered in future ecological and evolutionary studies of MHC-I in sparrows and other songbirds.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0970-7) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

et al. 2017

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Mouse–Human Orthology Relationships in an Olfactory Receptor Gene Cluster

et al. 2001

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The Phylogenetic History of the MHC Class I Gene Families in Pig, Including a Fossil Gene Predating Mammalian Radiation

Renard

Chardon

Vaiman

2003

Journal of Molecular Evolution

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More than 990 kb of the 1200 kb in the SLA class I region of the pig major histocompatibility complex (MHC) have been sequenced. The present study was designed to establish the evolution of this region which was best understood by distinguishing three periods. The most recent period, which extended from 40 to 15 mya, probably corresponded to five rounds of duplication of a basic unit. This unit consisted of a single class I gene linked to widely dispersed repeats, and one SLA-specific repeat motif. The duplications gave rise to six SLA classical class I genes. The second evolutionary period corresponded to the emergence of the SLA nonclassical class I genes, i.e. after the suidae separated from the other artiodactyl species about 65 mya. The third period appeared to correspond to a much more remote age when the ancestor of the gene SLA-11 existed. Comparative studies of the human and pig sequences of the class I-containing segments indeed revealed the presence within the human HSR1-ZNF segment of relics of a human class I fossil gene which appeared to be orthologous to the 5' moiety of the SLA-11 pseudogene. This was the first evidence that a class I gene existed in this location at least 110-120 mya in the MHC class I region of the precursor of the mammalian species. Human/pig sequence comparison also revealed that the presumably functional pig MIC2 gene was probably orthologous to the human functional MICA or MICB genes.

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A first map of the porcine major histocompatibility complex class I region

Cited by 29 publications

References 35 publications

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

Expression and phylogenetic analyses reveal paralogous lineages of putatively classical and non-classical MHC-I genes in three sparrow species (Passer)

Mouse–Human Orthology Relationships in an Olfactory Receptor Gene Cluster

The Phylogenetic History of the MHC Class I Gene Families in Pig, Including a Fossil Gene Predating Mammalian Radiation

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