Identification of IL-34 in teleost fish: differential expression of rainbow trout IL-34, MCSF1 and MCSF2, ligands of the MCSF receptor.

• Published in: Molecular Immunology
• Main Authors: Wang, Tiehui, Kono, Tomoya, Mira Monte, Milena, Kuse, Haruka, Costa, Maria M., Korenaga, Hiroki, Maehr, Tanja, Husain, Mansourah, Sakai, Masahiro, Secombes, Christopher J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2013
• Subjects: Amino Acid Sequence; Animals; Conserved Sequence; Cytokines/pharmacology; Exons; Gene Expression Regulation/drug effects/immunology; Humans; Interleukins/genetics/immunology; Introns; Macrophage Colony-Stimulating Factor/genetics/immunology; Macrophages/cytology/immunology/metabolism; Molecular Sequence Data; Oncorhynchus mykiss/genetics/immunology; Phylogeny; Protein Isoforms/genetics/immunology; Receptor; Recombinant Proteins/genetics/immunology; Sequence Homology; Amino Acid; Life sciences; Veterinary medicine & animal health; Sciences du vivant; Médecine vétérinaire & santé animale; Atlantic salmon
• Online Access: https://orbi.uliege.be/handle/2268/205342; https://doi.org/10.1016/j.molimm.2012.09.008

peer reviewed The mononuclear phagocyte system is composed of monocytes, macrophages and dendritic cells and has crucial roles in inflammation, autoimmunity, infection, cancer, organ transplantation and in maintaining organismal homeostasis. Interleukin-34 (IL-34) and macrophage colony stimulating factor (MCSF), both signalling through the MCSF receptor, regulate the mononuclear phagocyte system. A single IL-34 and MCSF gene are present in tetrapods. Two types of MCSF exist in teleost fish which is resulted from teleost-wide whole genome duplication. In this report, we first identified and sequence analysed six IL-34 genes in five teleost fish, rainbow trout, fugu, Atlantic salmon, catfish and zebrafish. The fish IL-34 molecules had a higher identity within fish group but low identities to IL-34s from birds (27.2-33.8%) and mammals (22.2-31.4%). However, they grouped with tetrapod IL-34 molecules in phylogenetic tree analysis, had a similar 7 exon/6 intron gene organisation, and genes in the IL-34 loci were syntenically conserved. In addition, the regions of the four main helices, along with a critical N-glycosylation site were well conserved. Taken together these data suggest that the teleost IL-34 genes described in this report are orthologues of tetrapod IL-34. Comparative expression study of the three trout MCSFR ligands revealed that IL-34, MCSF1 and MCSF2 are differentially expressed in tissues and cell lines. The expression of MCSF1 and MCSF2 showed great variance in different tissues and cell lines, suggesting a role in the differentiation and maintenance of specific macrophage lineages in specific locations. The relatively high levels of IL-34 expression across different tissues suggests a homeostatic role of IL-34 for the macrophage lineage in fish. One striking observation in the present study was the lack of induction of MCSF1 and MCSF2 expression but the quick induction of IL-34 expression by PAMPs and inflammatory cytokines in cell lines and primary head kidney macrophages in rainbow trout. In a ...