The chicken B locus is a minimal essential major histocompatibility complex

Kaufman, Jim; Milne, Sarah; Göbel, Thomas; Walker, Brian A.; Jacob, Jansen; Auffray, Charles; Zoorob, Rima; Beck, Stephan

doi:10.1038/44856

Cited by 547 publications

(518 citation statements)

References 24 publications

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“…Peptides transported by the 'restrictive' rat TAP2B presumably can be loaded onto TAP2B-linked class I molecules more efficiently [11][12][13]. A similar phenomenon is believed to occur in chickens, in which there is extremely tight genetic linkage between class Ia and TAP1/2 [10,14], and TAP1 lineages have also been described in hamsters [15]. These observations point to co-evolution among TAP and class I genes, so that antigen presentation might be efficiently carried out between certain combinations of TAP2 and/or TAP1 and class Ia allelic products.…”

Section: Introductionmentioning

confidence: 85%

Two highly divergent ancient allelic lineages of the transporter associated with antigen processing (TAP) gene in Xenopus: further evidence for co‐evolution among MHC class I region genes

et al. 2003

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In the frog Xenopus, MHC class I antigen presentation and processing genes (the immunoproteasome LMP2 and LMP7 and the transporter TAP1 and TAP2) seem to be closely linked in a primordial organization. Two distinct lineages of class Ia and LMP7 loci were previously identified, thus strongly suggesting co-evolution among 'class I region' genes. We now show that the Xenopus MHC 'class I region' lies between class II and class III genes and we have isolated two distinct alleles at both the TAP1 and TAP2 loci. The alleles at each locus are remarkably divergent from each other and phylogenetic tree analysis revealed in both cases that they diverged from each other 60-100 million years ago (MYA). For lineage-frequency and linkage analysis, 25 wild-caught X. laevis and 16 X. tropicalis were examined. The two lineages were present in different frequencies for X. laevis and X. tropicalis. Nevertheless, in all cases, the LMP7, TAP1, and TAP2 lineages were found in a set comprising one of the two lineages. Furthermore, like the LMP7 lineages, the TAP lineages were detected in most Xenopus species that diverged from a common ancestor 80-100 MYA, suggesting that the 'class I region' biallelic lineages are under balancing selection.

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Section: Introductionmentioning

confidence: 85%

Two highly divergent ancient allelic lineages of the transporter associated with antigen processing (TAP) gene in Xenopus: further evidence for co‐evolution among MHC class I region genes

et al. 2003

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“…They are not organized in an especially compact region as found in chicken MHC locus, where 11 genes are found in ϳ44 kb, with intergenic distances (excluding promoters) as small as 30 bp (15). The average GC content for the CD8␣ locus is ϳ49.36%, which is higher than the average 38.68% GC for chromosome 4q where the locus resides but lower than the MHC locus (roughly 60% GC) (14,15). Furthermore, these CD8␣-like receptor genes possess the following characteristics.…”

Section: Cd8␣ and Cd8␤ Bracket A Family Of Novel Multigenes Belongingmentioning

confidence: 99%

Genomic Organization of the Chicken CD8 Locus Reveals a Novel Family of Immunoreceptor Genes

Liaw

Chen

Huang

et al. 2007

The Journal of Immunology

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The genomic organization of the chicken CD8α gene was investigated to determine the basis of its polymorphism. Contiguous to the CD8α gene we identified multiple DNA blocks possessing sequences homologous to CD8α. Gene conversions and recombination over evolutionary time among CD8α and these CD8α homologous genes seem to account for the observed polymorphism. Furthermore, these CD8α-like DNAs encode a distinct multigene family of immunoreceptors that have a charged or polar residue in place of the interspecies-conserved CD8α transmembrane proline residue and a short cytoplasmic tail nonhomologous to CD8α. The identification of this novel multigene family with an organization reminiscent of human killer Ig-like receptors raises compelling questions on their evolutionary relationship among immunoreceptors.

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“…All genes located in the chicken MHC locus do have human homologues, e.g., TAP genes, tapasin, complement component C4, but not all human MHC genes are present in chicken and the different gene class regions are organized in a different way (Kaufman 2008). The chicken MHC locus represents a minimized set of genes conserved over the period of evolution between aves and mammals (Kaufman et al 1999). It can therefore not be ruled out that immunoproteasome genes have been lost from the chicken MHC locus and inserted elsewhere.…”

Section: Introductionmentioning

confidence: 99%

No evidence for immunoproteasomes in chicken lymphoid organs and activated lymphocytes

Erath

Groettrup

2014

Immunogenetics

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The proteasome is the main protein-degrading machine within the cell, producing ligands for MHC class I molecules. It is a cylindrical multicatalytic protease complex, and the catalytic activity is mediated by the three subunits β1, β2, and β5 which possess caspase-, trypsin-, and chymotrypsin-like activities, respectively. By stimulation with interferon (IFN)-γ the replacement of these subunits by β1i, β2i, and β5i is induced leading to formation of immunoproteasomes with altered proteolytic and antigen processing properties. The genes coding for these immunosubunits are restricted to jawed vertebrates but have so far not been found in the genomes of birds, e.g., chicken, turkey, quail, black grouse and zebra finch. However, the chicken genome sequences are not completely assigned; therefore, we investigated the presence of immunoproteasome on protein level. 20S proteasome was purified from the chicken brain, blood, spleen, and bursa of Fabricius, followed by separation via two-dimensional (2D) gel electrophoresis. We analyzed the protein spots derived from the spleen and brain by mass spectrometry and could identify all 14 proteasomal subunits, but there were no differences detectable in the spot patterns. Moreover, we stimulated the chicken spleen cells with phorbol 12-myristate 13-acetate (PMA) and ionomycin aiming at the induction of immunoproteasome, but in spite of the induction of proliferation and IFN-γ, no evidence for immunoproteasome formation in chicken could be obtained. This result was substantiated by the finding that 20S proteasomes isolated from immune and non-immune tissues showed very similar peptidolytic activities. Taken together, our results indicate that chicken lack immunoproteasomes also on protein level.

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The chicken B locus is a minimal essential major histocompatibility complex

Cited by 547 publications

References 24 publications

Two highly divergent ancient allelic lineages of the transporter associated with antigen processing (TAP) gene in Xenopus: further evidence for co‐evolution among MHC class I region genes

Two highly divergent ancient allelic lineages of the transporter associated with antigen processing (TAP) gene in Xenopus: further evidence for co‐evolution among MHC class I region genes

Genomic Organization of the Chicken CD8 Locus Reveals a Novel Family of Immunoreceptor Genes

No evidence for immunoproteasomes in chicken lymphoid organs and activated lymphocytes

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