Primitive Synteny of Vertebrate Major Histocompatibility Complex Class I and Class II Genes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 97; no. 9; pp. 4712 - 4717
• Main Authors: Ohta, Yuko, Okamura, Kazuhiko, McKinney, E. Churchill, Bartl, Simona, Hashimoto, Keiichiro, Flajnik, Martin F.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 25.04.2000; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Alleles; Amino Acid Sequence; Animals; Base Sequence; Biological Evolution; Biological Sciences; Chondrichthyes; DNA Primers; Evolution; Exons; Female; Fish; Fishes - classification; Fishes - genetics; Fishes - immunology; Gene Library; Genes, MHC Class I; Genes, MHC Class II; Genetic Linkage; Genetics; Genomics; Haplotypes; Immunology; MHC class I genes; MHC class II genes; Microbiology; Molecular Sequence Data; Nurses; Pisces; Polymerase Chain Reaction; Sequence Alignment; Sequence Homology, Amino Acid; Sharks; Sharks - classification; Sharks - genetics; Sharks - immunology; Teleostei; Vertebrates; Vertebrates - classification; Vertebrates - genetics; Vertebrates - immunology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.97.9.4712

Major histocompatibility complex (MHC) class I and class II molecules bind to and display peptidic antigens acquired from pathogens that are recognized by lymphocytes coordinating and executing adaptive immune responses. The two classes of MHC proteins have nearly identical tertiary structures and were derived from a common ancestor that probably existed not long before the emergence of the cartilaginous fish. Class I and class II genes are genetically linked in tetrapods but are not syntenic in teleost fish, a phylogenetic taxon derived from the oldest vertebrate ancestor examined to date. Cartilaginous fish (sharks, skates, and rays) are in the oldest taxon of extant jawed vertebrates; we have carried out segregation analyses in two families of nurse sharks and one family of the banded houndshark that revealed a close linkage of class IIα and β genes both with each other and with the classical class I (class Ia) gene. These results strongly suggest that the primordial duplication giving rise to classical class I and class II occurred in cis, and the close linkage between these two classes of genes has been maintained for at least 460 million years in representatives of most vertebrate taxa.