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MHC genes IN INVERTEBRATES: THE ECHINODERMATA

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  • GenoSplice technology

Abstract

For the first time MHC ClassII gene was described in Echinodermata, so in Invertebrates. For the present time MHC ClassI gene was not found in a significant manner but further studies are necessary to conclude about its existence in Echinodermata. INTRODUCTION: As C.A Janeway wrote in 2001(Ref.1):
MHC genes IN INVERTEBRATES: THE ECHINODERMATA
by Michel Leclerc, Ariane Jolly° and Pierre de la Grange°
556 rue Isabelle Romée, 45640 SANDILLON (FRANCE)
°Genosplice, PARIS (FRANCE)
mleclerc45@gmail.com
Abstract:For the first time MHC ClassII gene was described in Echinodermata, so in
Invertebrates. For the present time MHC ClassI gene was not found in a significant manner
but further studies are necessary to conclude about its existence in Echinodermata.
INTRODUCTION:
As C.A Janeway wrote in 2001( Ref.1):
"The function of MHC molecules is to bind peptide fragments derived from pathogens and display them
on the cell surface for recognition by the appropriate T cells. The consequences are almost always
deleterious to the pathogen—virus-infected cells are killed, macrophages are activated to
kill bacteria living in their intracellular vesicles, and B cells are activated to produce antibodies that
eliminate or neutralize extracellular pathogens. Thus, there is strong selective pressure in favor of any
pathogen that has mutated in such a way that it escapes presentation by an MHC molecule.
Two separate properties of the MHC make it difficult for pathogens to evade immune responses in this
way. First, the MHC is polygenic: it contains several different MHC class I and MHC class II genes, so
that every individual possesses a set of MHC molecules with different ranges of peptide-binding
specificities. Second, the MHC is highlypolymorphic; that is, there are multiple variants of each gene
within the population as a whole. The MHC genes are, in fact, the most polymorphic genes known
Because of the polygeny of the MHC, every person will express at least three different antigen-
presenting MHC class I molecules and three (or sometimes four) MHC class II molecules on his or her
cells . In fact, the number of different MHC molecules expressed on the cells of most people is greater
because of the extreme polymorphism of the MHC and the codominant expression of MHC gene
products.
The term polymorphism comes from the Greek poly, meaning many, and morphe, meaning shape or
structure. As used here, it means within-species variation at a gene locus, and thus in its protein product;
the variant genes that can occupy the locus are termed alleles. There are more than 200 alleles of some
human MHC class I and class II genes, each allele being present at a relatively high frequency in the
population. So there is only a small chance that the corresponding MHC locus on both the homologous
chromosomes of an individual will have the same allele; most individuals will be heterozygous at MHC
loci. The particular combination of MHC alleles found on a single chromosome is known as an MHC
haplotype. Expression of MHC alleles is codominant, with the protein products of both the alleles at a
locus being expressed in the cell, and both gene products being able to present antigens to T cells. The
extensive polymorphism at each locus thus has the potential to double the number of different MHC
molecules expressed in an individual and thereby increases the diversity already available through
polygeny .
In addition to the highly polymorphic ‘classical’ MHC class I and class II genes, there are many genes
encoding MHC class I-type molecules that show little polymorphism; most of these have yet to be
assigned a function. They are linked to the class I region of the MHC and their exact number varies
greatly between species and even between members of the same species. These genes have been
termed MHC class IB genes; like MHC class I genes, they encode β2-microglobulin-associated cell-
surface molecules. Their expression on cells is variable, both in the amount expressed at the cell surface
and in the tissue distribution "
In human, the main function of major histocompatibility complex (MHC) Class II molecules,
is to present processed antigens which are derived primarily, from exogeneous sources.
Constitutive expression of MHC Class II molecules, is also confined to professional antigen-
presenting cells (APC) of the immune system ( Ref.2)
Since we have discovered the IPA (Invertebrate Primitive Antibody)(Ref. 3,4,5,6), to acquire a
better understanding of the invertebrate immune system , it seemed useful to look for MHC
genes(HLA-DRB1 gene)(HLA-C gene) in invertebrates with Ophiocomina nigra (Ophuirids),
Antedon bifida (Crinoïds) as model of studies.On the other hand we 'll have a look on a MHC
Class I gene(HLA-C gene) corresponding to a molecule which is a heterodimer consisted of a
heavy chain and a light one( beta-2 microglobulin).
MATERIALS AND METHODS:
Animals :Ophiocomina nigra (Ophuirid) Antedon bifida(Crinoïd) were obtained at the station
« Of Biologie Marine of Roscoff » France.
Obtention of ophuirid and crinoïd mRNA :Digestive coeca were excised from their bodies and
mRNA were obtained from Uptizol (Interchim) then quality controls were operated. (Ref.7)
Sequencing : Sequencing was made on Illumina Next Seq 500 with paired-end : 2. 75 bp
Transcriptome was assembled from RNA-Seq fastq files using Trinity v2.1.1 ( Ref.8) with default
parameters. A BLAST database was created with the assembled transcripts using makeblastdb
application from ncbi-blast+ (v2.2.31+). The sequences of transcripts of interest were then blasted
against this database using blastn application from ncbi-blast+ ( Ref.9) with parameter word_size 7.
RESULTS:
MHC gene Class II appears in the genome of Ophiocomina nigra and Antedon bifida one, in a
significant manner. The transcriptomes are given in the following tables, with the sequences just
after.First Ophiocomina nigra results show the"HLA-DRB1" transcriptome which possesses a short
sequence but a specific one.
QueryID Quer
Name SubjectID Identity
(%) Length Mismatc
hGapopen Query cover
(%) E-value Bitscore
  
     
>TRINITY_DN4807_c1_g1_i1
5'CATATAGTTTAGGGGGTTATAAAAAAATGACTCCGGTTACTGACATATTTGGGACCCCAA
CTGTCCAAAGAAAATTATAGCCCCTATAAATTATAATTTATTAATTTTTGTTTTCTCTTG
TATAGGGACCAGAGCCAATCCCACTGGAAGTTAGGGCACGAGCAGTCAAAGACCAATTTT
AAATGTAAAAAAAAAAAAAAAAAAAAATAAAAAATTAAAAAAAAAAAAAAAAAAATAAAA
AATTAAAAAAAAAAAAAAAAAAATAAA3'
Secondly with A.bi'da:
We 'nd the transcriptome called HLA-DRB1 Antedon bi'da with the following e-value,
identity, bitscore:
QueryID Query Name SubjectID Identity
(%) Length Mismatch Gapopen Query cover (%) E-value Bitscore
  
     
 !" #$ % !%!&&!"'("!)*"'!)!"'+,!'% !)"!-'+!, !'.$+/!0.''1%)!%+)!2$,!+ 1)%"!*3!
". 4!)"!-'**'(%
>TRINITY_DN20232_c5_g3_i1
5'GCATGCCTGTAATCCCAGCTACTTGGGAGGCTGAGGCAGGAGAATCACTTGAACCCAGGA
GGCAGAGGTTGTGGTGAGCCGAGATCATGCCATCGCACTCCAGCCTGGGCAATAAGAGCG
AAACTCCGGTCTCAAACAAACAAACAAAAAACAAAACAAAAACAAACAAAAAACAAAACA
AAAACAAACAAAAAACAAAACAAA3'
MHC ClassI gene was not found, at least in a significant manner (the e-value was not
significative)
CONCLUSION:
It is obvious that MHC classII gene(HLA-DRB1 gene) exist in Echinodermata, at least in
Echinodermata which possess a sophisticated immune system as Asterids, Ophuirids, Crinoïds. It
would be interesting also to study MHC system in Echinodermata which present only innate
immune response as Echinids, Holothurids (Ref.10)
The HLA-DRB1 gene is a part of a family of genes called the human leukocyte antigen (HLA)
complex.
 !.+', % %'/ /!23!,"! % !2 *'%"!,'!, !!*)""! 2 ,)!
)%!.)+)*'$ "! !*)""!!1'* $* !"!)! , +'/1 +!'%"",%!'-!)%!)*.)!
56!)%/!)!2 ,)!)%!56!2',!)%'+ /!%!, !1 12+)% !,!.*)3"!)!
 %,+)*!+'* !%!, !11$% !"3", 1 23!.+ " %,%!. .,/ "!/ +7 /!-+'1!
8,+) **$*)+!.+', %"!,'!! *. +! **"!9*)""!!1'* $* "!)+ !'%",,$,7 *3!
8.+ "" /!%!.+'- ""'%)*!)%, %!.+ " %,%! **" 5:9!!*31.'3, "!
/ %/+,! **"!1)+'.) "6 )%/!'$*/!2 !%/$ /!%!%'%.+'- ""'%)*!:9"
!"! 8.+ "" /!),!)!* 7 *!47 !,1 "! +!,)%!,"!
.)+)*'$ "!!!)%/!!!"!.+ " %,!%!)**!%/7/$)*"!** *!
7)+)%,"!'-!!)+ !*%; /!(,! , +!%'% !'+!'% !'-!, ! % "!!!
)%/!! + !)+ !!+ *), /!." $/' % "!!!!
DRB8 and DRB9.
We try now to look for MHC class I genes in Ophuirids and Crinoïds.
The HLA-C gene ( we looked for) belongs also to the HLA complex: it helps the immune system to
distinguish the body own proteins from proteins made by foreign invaders such as viruses and
bacteria (Ref . 11, 12, 13)
Although all efforts to find in Invertebrates a Major Histocompatibility Complex System have been
unsuccessful, we find to day, for the first time, a MHC class II gene (HLA-DRB1 gene) in
Echinodermata: It's of great novelty.It's a fundamental discovery in the domain of Comparative
Immunology.
REFERENCES:
1)Janeway, C.A et al (2001) Immunobiology New York Garland Sciences ed.
2) Holling , T.M et al (2004) Function and regulation of MHC class II molecules in T lymphocytes:
of mice and men. Hum.Immunol 65(4) 282-289
3)Leclerc, M. (2018) The complement system in Echinodermata includes the Lectin Pathway.
Archives of Immunology and Allergy 1(2) 1-2
4) Leclerc, M. et al(2016) Evidence of Fab gene in an Invertebrate: Ophiocomina nigra
(Echinodermata. E.C Microbiology 3(5) 539-41
5) Leclerc, M et al (2016) Evidence of Fc receptor gene in an Invertebrate: Ophiocomina nigra
(Echinodermata. E.C Microbiology 4(5) 759-60
6)Leclerc, M. et al (2018) Evidence of immune genes in the crinoïd: Antedon bifida. Evidence of a
A.bifida IGKappa gene, Fc receptor gene. Int. J.Vaccine Res 3(1) 1-2
7)Vincent, N. et al (2014) A new gene in A. Rubens A sea star IGKappa gene. Meta Gene 2 320-22
8) Grabher, M.G et al (2011) Full-length transcriptome assembly from RNA-seq data without a
reference genome. Nature Biotechnology 29 644-52
9) Altschul, S.F et al (1990) Basic local Alignment search tool. J.Mol.Biol 215(3) 403-10
10)Leclerc,M. (2018)Evidence of complement genes in the crinoïd A. Bifida. Comparisons with
other Echinodermata. Int. J. Biotech. And Bioeng 5(1) 17-18
11)Hiby, S.E et al (2004) Combinations of material KIR and fetal HLA-C genes influence the risk
of preeclampsis and reproductive success. J. Exp. Med 200(8) 957-65
12)Khakoo, S.I (2004)HLA and NK cell inhibitory receptor genes in resolving hepatitis C virus
infection. Science 305 872-74
13) Nair, R.P et al (2006)Sequence and haplotype analysis supports HLA-C as the psoriasis
susceptibility 1 gene. AJHG 78(5) 827-51
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