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An Ancestral Major Histocompatibility Complex Organization in Cartilaginous Fish: Reconstructing MHC Origin and Evolution.

ABSTRACT: Cartilaginous fish (sharks, rays, and chimeras) comprise the oldest living jawed vertebrates with a mammalian-like adaptive immune system based on immunoglobulins (Ig), T-cell receptors (TCRs), and the major histocompatibility complex (MHC). Here, we show that the cartilaginous fish "adaptive MHC" is highly regimented and compact, containing (i) a classical MHC class Ia (MHC-Ia) region containing antigen processing (antigen peptide transporters and immunoproteasome) and presenting (MHC-Ia) genes, (ii) an MHC class II (MHC-II) region (with alpha and beta genes) with linkage to beta-2-microglobulin (β2m) and bromodomain-containing 2, (iii) nonclassical MHC class Ib (MHC-Ib) regions with 450 million-year-old lineages, and (iv) a complement C4 associated with the MHC-Ia region. No MHC-Ib genes were found outside of the elasmobranch MHC. Our data suggest that both MHC-I and MHC-II genes arose after the second round of whole-genome duplication (2R) on a human chromosome (huchr) 6 precursor. Further analysis of MHC paralogous regions across early branching taxa from all jawed vertebrate lineages revealed that Ig/TCR genes likely arose on a precursor of the huchr9/12/14 MHC paralog. The β2m gene is linked to the Ig/TCR genes in some vertebrates suggesting that it was present at 1R, perhaps as the donor of C1 domain to the primordial MHC gene. In sum, extant cartilaginous fish exhibit a conserved and prototypical MHC genomic organization with features found in various vertebrates, reflecting the ancestral arrangement for the jawed vertebrates.

SUBMITTER: Verissimo A

PROVIDER: S-EPMC10751288 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

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An Ancestral Major Histocompatibility Complex Organization in Cartilaginous Fish: Reconstructing MHC Origin and Evolution.

Veríssimo Ana A Castro L Filipe C LFC Muñoz-Mérida Antonio A Almeida Tereza T Gaigher Arnaud A Neves Fabiana F Flajnik Martin F MF Ohta Yuko Y

Molecular biology and evolution 20231201 12

Cartilaginous fish (sharks, rays, and chimeras) comprise the oldest living jawed vertebrates with a mammalian-like adaptive immune system based on immunoglobulins (Ig), T-cell receptors (TCRs), and the major histocompatibility complex (MHC). Here, we show that the cartilaginous fish "adaptive MHC" is highly regimented and compact, containing (i) a classical MHC class Ia (MHC-Ia) region containing antigen processing (antigen peptide transporters and immunoproteasome) and presenting (MHC-Ia) genes ...[more]

PMID: 38059517

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Dataset Information

An Ancestral Major Histocompatibility Complex Organization in Cartilaginous Fish: Reconstructing MHC Origin and Evolution.

Publications

An Ancestral Major Histocompatibility Complex Organization in Cartilaginous Fish: Reconstructing MHC Origin and Evolution.

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