Characterization and expression analysis of tandemly-replicated asc genes in the Japanese medaka, Oryzias latipes.

ASC is a component of the inflammasome playing crucial roles in the inflammatory response. In mammals, ASC induces pyroptosis and inflammatory cytokine production. In this study, three asc genes (asc1, asc2, and asc3) from the Japanese medaka (Oryzias latipes) were identified and characterized. These asc genes were tandem replicates on chromosome 16, and their exon-intron structures differed between them. All three ASCs conserved the pyrin and caspase-recruitment domains, which are important for inflammasome formation. In phylogenetic analysis, all ASCs clustered with those of other teleosts. The asc1 expression levels were significantly higher in several organs than those of asc2 and asc3, suggesting that asc1 may act as a dominant asc in the Japanese medaka. Expression of the three asc genes showed different patterns during Aeromonas hydrophila and Edwardsiella piscicida infections. Furthermore, their expression was adequately down-regulated in the medaka fin-derived cells stimulated with ATP for 12 h, while asc2 expression was statistically up-regulated after nigericin stimulation for 24 h. Moreover, the expression of asc2 and asc3 was significantly higher in the skin of ASC-1-knockout medaka than in that of the wild type medaka during A. hydrophila infection.

Genome-Wide Analysis of LysM-Containing Gene Family in Wheat: Structural and Phylogenetic Analysis during Development and Defense.

The lysin motif (LysM) family comprise a number of defense proteins that play important roles in plant immunity. The LysM family includes LysM-containing receptor-like proteins (LYP) and LysM-containing receptor-like kinase (LYK). LysM generally recognizes the chitin and peptidoglycan derived from bacteria and fungi. Approximately 4000 proteins with the lysin motif (Pfam PF01476) are found in prokaryotes and eukaryotes. Our study identified 57 LysM genes and 60 LysM proteins in wheat and renamed these genes and proteins based on chromosome distribution. According to the phylogenetic and gene structure of intron-exon distribution analysis, the 60 LysM proteins were classified into seven groups. Gene duplication events had occurred among the LysM family members during the evolution process, resulting in an increase in the LysM gene family. Synteny analysis suggested the characteristics of evolution of the LysM family in wheat and other species. Systematic analysis of these species provided a foundation of LysM genes in crop defense. A comprehensive analysis of the expression and cis-elements of LysM gene family members suggested that they play an essential role in defending against plant pathogens. The present study provides an overview of the LysM family in the wheat genome as well as information on systematic, phylogenetic, gene duplication, and intron-exon distribution analyses that will be helpful for future functional analysis of this important protein family, especially in Gramineae species.

Four selenoprotein P genes exist in salmonids: Analysis of their origin and expression following Se supplementation and bacterial infection.

The following research was conducted to elucidate the evolution and expression of salmonid selenoprotein P (SelP), a selenoprotein that is unique in having multiple selenocysteine (Sec) residues, following supranutritional selenium supplementation and infection in rainbow trout. We show that in salmonids SelP is present as four paralogues and that the diversification of SelP genes during vertebrate evolution relates to whole genome duplication events. With 17 and 16 selenocysteine residues for rainbow trout (Oncorhynchus mykiss)/Atlantic salmon (Salmo salar) SelPa1 and SelPa2 proteins respectively and 1 or 2 (trout or salmon) and 4 or 3 (trout or salmon) selenocysteine residues for salmonid SelPb1 and SelPb2 proteins respectively, this is the highest number of (predicted) multiple selenocysteine containing SelP proteins reported for any vertebrate species to date. To investigate the effects of selenium form on SelP expression we added different concentrations (1 nM- 10 µM) of organic or inorganic selenium to a trout cell line (RTG-2 cells) and analysed changes in mRNA abundance. We next studied the impact of supplementation on the potential modulation of these transcripts by PAMPs and proinflammatory cytokines in RTG-2 and RTS-11 cells. These experiments revealed that selenium type influenced the responses, and that SelP gene subfunctionalisation was apparent. To get an insight into the expression patterns in vivo we conducted a feeding trial with 2 diets differing in selenium content and 5 weeks later challenged the trout with a bacterial pathogen (Aeromonas salmonicida). Four tissues were analysed for SelP paralogue expression. The results show a significant induction of SelPa1 in gills and intestine following infection in selenium supplemented fish and for SelPa2 in gills. SelPb1 was significantly reduced in head kidney of both diet groups following infection, whilst SelPb2 was significantly upregulated in skin of both diet groups post infection. Overall these findings reveal differential expression profiles for the SelPa/SelPb paralogues in trout, influenced by selenium supply, cell type/tissue and stimulant. The increase of multiple Sec containing SelP proteins in salmonids could indicate an enhanced requirement for selenium in this lineage.

CHRFAM7A, a human-specific and partially duplicated α7-nicotinic acetylcholine receptor gene with the potential to specify a human-specific inflammatory response to injury.

Conventional wisdom presumes that the α7nAChR product of CHRNA7 expression mediates the ability of the vagus nerve to regulate the inflammatory response to injury and infection. Yet, 15 years ago, a 2nd structurally distinct and human-specific α7nAChR gene was discovered that has largely escaped attention of the inflammation research community. The gene, originally called dupα7nAChR but now known as CHRFAM7A, has been studied exhaustively in psychiatric research because of its association with mental illness. However, dupα7nAChR/CHRFAM7A expression is relatively low in human brain but elevated in human leukocytes. Furthermore, α7nAChR research in human tissues has been confounded by cross-reacting antibodies and nonspecific oligonucleotide primers that crossreact in immunoblotting, immunohistochemistry, and RT-PCR. Yet, 3 independent reports show the human-specific CHRFAM7A changes cell responsiveness to the canonical α7nAChR/CHRNA7 ion-gated channel. Because of its potential for the injury research community, its possible significance to human leukocyte biology, and its relevance to human inflammation, we review the discovery and structure of the dupα7nAChR/CHRFAM7A gene, the distribution of its mRNA, and its biologic activities and then discuss its possible role(s) in specifying human inflammation and injury. In light of emerging concepts that point to a role for human-specific genes in complex human disease, the existence of a human-specific α7nAChR regulating inflammatory responses in injury underscores the need for caution in extrapolating findings in the α7nAChR literature to man. To this end, we discuss the translational implications of a uniquely human α7nAChR-like gene on new drug target discovery and therapeutics development for injury, infection, and inflammation.

Toll-like receptors in bony fish: from genomics to function.

Receptors that recognize conserved pathogen molecules are the first line of cellular innate immunity defense. Toll-like receptors (TLRs) are the best understood of the innate immune receptors that detect infections in mammals. Key features of the fish TLRs and the factors involved in their signaling cascade have high structural similarity to the mammalian TLR system. However, the fish TLRs also exhibit very distinct features and large diversity which is likely derived from their diverse evolutionary history and the distinct environments that they occupy. Six non-mammalian TLRs were identified in fish. TLR14 shares sequence and structural similarity with TLR1 and 2, and the other five (TLR19, 20, 21, 22 and 23) form a cluster of novel TLRs. TLR4 was lost from the genomes of most fishes, and the TLR4 genes found in zebrafish do not recognize the mammalian agonist LPS and are likely paralogous and not orthologous to mammalian TLR4 genes. TLR6 and 10 are also absent from all fish genomes sequenced to date. Of the at least 16 TLR types identified in fish, direct evidence of ligand specificity has only been shown for TLR2, TLR3, TLR5M, TLR5S and TLR22. The common carp TLR2 was shown to recognize the synthetic triacylated lipopeptide Pam(3)CSK(4) and lipopeptides from gram positive bacteria. The membrane-bound TLR5 (TLR5M) signaling in response to flagellin in rainbow trout is amplified through interaction with the soluble form (TLR5S) in a positive loop feedback. In Fugu, TLR3 is localized to the endoplasmic reticulum (ER) and recognizes relatively short dsRNA, while TLR22 has a surveillance function like the human cell-surface TLR3. Genome and gene duplications have been major contributors to the teleost's rich evolutionary history and genomic diversity. Duplicate or multi-copy TLR genes were identified for TLR3 and 7 in common carp, TLR4b, 5, 8 and 20 in zebrafish, TLR8a in rainbow trout and TLR22 in rainbow trout and Atlantic salmon. The main task for current and near-future fish TLRs research is to develop specificity assays to identify the ligands of all fish TLRs, which will advance comparative immunology research and will contribute to our understanding of disease resistance mechanisms in fish and the development of new adjuvants and/or more effective vaccines and therapeutics.