A single immunoglobulin-domain IgSF protein from Sciaenops ocellatus regulates pathogen-induced immune response in a negative manner

• Published in: Developmental & Comparative Immunology
• Main Authors: Cheng, Shun-feng, Hu, Yong-hua, Sun, Bo-guang, Zhang, Min, Chi, Heng, Sun, Li, Sun, L (reprint author), Chinese Acad Sci, Inst Oceanol, Key Lab Expt Marine Biol, 7 Nanhai Rd, Qingdao 266071, Peoples R China.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2012
• Subjects: Sciaenops Ocellatus; Immunoglobulin Superfamily (Igsf); Novel Immune Type Receptors (Nitrs); Immunoregulatory Receptor; Immunology; Zoology; Red drum; Sciaenops ocellatus
• Online Access: http://ir.qdio.ac.cn/handle/337002/12270; https://doi.org/10.1016/j.dci.2012.04.012

The immunoglobulin superfamily (IgSF) is a large group of cell surface proteins that include various immunoregulatory receptors such as novel immune type receptors (NITRs), which are a family of diversified proteins found exclusively in body fish. In this study, we identified and analyzed an IgSF protein, SolgSF1, from red drum (Sciaenops oceans). SoIgSF1 is composed of 225 amino acid residues and moderately related to teleost NITRs. In silico analysis indicated that SoIgSF1 is a type I transmembrane glycoprotein and contains an N-terminal signal peptide sequence, a single extracellular immunoglobulin V domain, a transmembrane region, and a cytoplasmic region. However, unlike most NITRs, the cytoplasmic region of SoIgSF1 exhibits no consensus inhibitory or stimulatory signaling sequences but has two tyrosine-containing motifs that conform to the right-half sequence of the immunoreceptor tyrosine-based inhibitory motif (ITIM). Quantitative real time RT-PCR analysis showed that SolgSF1 expression occurred mainly in immune organs and was drastically induced by viral and bacterial infection. Immunofluorescence microscopy indicated that viral infection of head kidney (HK) leukocytes induced surface expression of SolgSF1, which was able to interact with antibodies against recombinant SoIgSF1. Antibody cross-linking of SolgSF1 on HK leukocytes inhibited the expression of immune relevant genes and promoted viral and bacterial infection. Taken together, these results indicate that SolgSF1, though lacking canonical intracellular signaling motifs, is involved in regulation of host immune response during pathogen infection possibly by functioning as a negative signaling receptor through a novel mechanism. (C) 2012 Elsevier Ltd. All rights reserved.