Molecular characterization of the cytotoxic and regulatory T cell coreceptor (CRTAM), and its ligand CADM1, in the European seabass and gilthead seabream

• Published in: Fish & shellfish immunology 2023-03, Vol.134, p.108569-108569, Article 108569
• Main Authors: García-Álvarez, Miguel Ángel, González-Fernández, Carmen, Esteban, María Ángeles, Cuesta, Alberto
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic Agents; Bass; CADM1; Cell Adhesion Molecule-1; CRTAM; Environmental Sciences; European seabass; Gilthead seabream; Immunology; Life Sciences; Ligands; Mammals; Nodavirus; Sea Bream; T cells; T-Lymphocytes, Regulatory
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2023.108569

T cell activation is a multifaceted process that depends on the activation of the T cell receptor (TCR). However, other coreceptors are also strictly necessary to provide co-signals and modulate the immune response. However, to date, most of these coreceptors are unknown in fish or their information is very limited. Therefore, in this work, we have identified the cytotoxic and regulatory T cell molecule, CRTAM, and its ligand, the cell adhesion molecule 1, CADM1, in European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata); and evaluated their transcriptional levels. Both putative proteins showed the canonical architecture observed in mammals, where CRTAM exhibited two immunoglobulin domains and CADM1, both the a and b forms, exhibited three of these domains. In addition, phylogeny and synteny analyses showed their conservation throughout vertebrate evolution. We found constitutive expression of all three genes, with crtam and cadm1a being predominant in immune tissues such as spleen, thymus and head-kidney (HK), while cadm1b expression was more limited to the brain. In vitro, only the T cell mitogen phytohemagglutinin (PHA) up-regulated the transcription of crtam and cadm1a in HK leucocytes. Nodavirus (NNV) infection elicited an up-regulation of crtam and cadm1a in brain and HK, appearing earlier in seabream than in seabass, which could explain the resistance of seabream to the development of nodavirus disease. In addition, they are up-regulated during the innate cell-mediated cytotoxic response in seabream but not in seabass. Altogether, our data seem to indicate that CRTAM is more related to the innate cytotoxicity in seabream and more in the specific and T cell-mediated cytotoxicity in seabass. Our results highlight the importance of CRTAM and CADM1 as important molecules in the activation of T lymphocytes in seabass and seabream, but further studies are needed. •CRTAM and CADM1 genes are present and well-conserved in seabream and seabass.•European seabass crtam is up-regulated by T cell mitogens.•CRTAM and CADM1a genes are mainly expressed in lymphoid tissues and brain.•Upon nodavirus infection, CRTAM is up-regulated earlier in seabream than in seabass.•CRTAM and CADM1a seem to be related to the cell-mediated cytotoxic response.