MHC and Evolution in Teleosts

Major histocompatibility complex (MHC) molecules are key players in initiating immune responses towards invading pathogens. Both MHC class I and class II genes are present in teleosts, and, using phylogenetic clustering, sequences from both classes have been classified into various lineages. The pol...

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Main Author: Unni Grimholt
Format: Article
Language:English
Published: MDPI AG 2016-01-01
Series:Biology
Subjects:
Online Access:http://www.mdpi.com/2079-7737/5/1/6
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author Unni Grimholt
author_facet Unni Grimholt
author_sort Unni Grimholt
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description Major histocompatibility complex (MHC) molecules are key players in initiating immune responses towards invading pathogens. Both MHC class I and class II genes are present in teleosts, and, using phylogenetic clustering, sequences from both classes have been classified into various lineages. The polymorphic and classical MHC class I and class II gene sequences belong to the U and A lineages, respectively. The remaining class I and class II lineages contain nonclassical gene sequences that, despite their non-orthologous nature, may still hold functions similar to their mammalian nonclassical counterparts. However, the fact that several of these nonclassical lineages are only present in some teleost species is puzzling and questions their functional importance. The number of genes within each lineage greatly varies between teleost species. At least some gene expansions seem reasonable, such as the huge MHC class I expansion in Atlantic cod that most likely compensates for the lack of MHC class II and CD4. The evolutionary trigger for similar MHC class I expansions in tilapia, for example, which has a functional MHC class II, is not so apparent. Future studies will provide us with a more detailed understanding in particular of nonclassical MHC gene functions.
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spelling doaj.art-f518f35667154f11affb69484dab1f572023-09-02T06:40:47ZengMDPI AGBiology2079-77372016-01-0151610.3390/biology5010006biology5010006MHC and Evolution in TeleostsUnni Grimholt0Department of Virology, Norwegian Veterinary Institute, Ullevaalsveien 68, Oslo N-0106, NorwayMajor histocompatibility complex (MHC) molecules are key players in initiating immune responses towards invading pathogens. Both MHC class I and class II genes are present in teleosts, and, using phylogenetic clustering, sequences from both classes have been classified into various lineages. The polymorphic and classical MHC class I and class II gene sequences belong to the U and A lineages, respectively. The remaining class I and class II lineages contain nonclassical gene sequences that, despite their non-orthologous nature, may still hold functions similar to their mammalian nonclassical counterparts. However, the fact that several of these nonclassical lineages are only present in some teleost species is puzzling and questions their functional importance. The number of genes within each lineage greatly varies between teleost species. At least some gene expansions seem reasonable, such as the huge MHC class I expansion in Atlantic cod that most likely compensates for the lack of MHC class II and CD4. The evolutionary trigger for similar MHC class I expansions in tilapia, for example, which has a functional MHC class II, is not so apparent. Future studies will provide us with a more detailed understanding in particular of nonclassical MHC gene functions.http://www.mdpi.com/2079-7737/5/1/6teleostrayfinned fishMajor histocompatibility complexMHC class IMHC class IIphylogenyevolution
spellingShingle Unni Grimholt
MHC and Evolution in Teleosts
Biology
teleost
rayfinned fish
Major histocompatibility complex
MHC class I
MHC class II
phylogeny
evolution
title MHC and Evolution in Teleosts
title_full MHC and Evolution in Teleosts
title_fullStr MHC and Evolution in Teleosts
title_full_unstemmed MHC and Evolution in Teleosts
title_short MHC and Evolution in Teleosts
title_sort mhc and evolution in teleosts
topic teleost
rayfinned fish
Major histocompatibility complex
MHC class I
MHC class II
phylogeny
evolution
url http://www.mdpi.com/2079-7737/5/1/6
work_keys_str_mv AT unnigrimholt mhcandevolutioninteleosts