Molecular characterization of cobia (Rachycentron canadum) CD4 homologues revealed the first evidence of soluble CD4 in fish. Issue 99 (April 2020)

• Record Type: Journal Article
• Authors: Tran, Hung Bao; Rizky, Putri Nurhanida; McDaniel Padgett, Stanley Rob; Lee, Yen-Hung; Chaung, Hso-Chi; Cheng, Ta-Chih
• Is Part Of: Fish & shellfish immunology. Issue 99(2020)
• Page Start: 239
• Page End: 242
• Publication Date: 2020-04
• Subjects: CD4-2 -- Embryonic development -- Rachycentron canadum -- Soluble CD4; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2020.02.017
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: The co-receptor CD4 plays an important role in distinguishing between helper T-cell (Th) and cytotoxic T lymphocyte (CTL). In the present study, we investigated the molecular features of CD4-2 cDNA to facilitate understanding of their roles in cobia ( Rachycentron canadum ). Two CD4-2 molecules have been identified and exhibited 16.10% amino acids identity with each other. The cDNA of CD4-2A consists of a 993 bp ORF encoding 330 aa with long intracytoplasmic tail containing conserved protein tyrosine kinase p56 Lck binding (C-X-C) motif, a transmembrane region, and two extracellular Ig-like (Ig-like) domains are predicted. Comparatively, the cDNA of cobia CD4-2B consists of a 990 bp ORF encoding 329 aa without a transmembrane domain as well as C-X-C motif, and three Ig-like domains are present. Homology comparison showed that the CD4-2A aa sequence of cobia showed high similarity and similar structural features to CD4-2 from other species, while the deduced CD4-2B protein shares higher structural similarity to CD4-1 group. Phylogenetic analysis indicated that cobia CD4-2A was closer with CD4-2 molecules in other fish species, distant from the clade formed by fish CD4-1 and mammalian CD4 sequences. However, cobia CD4-2B grouped with other known teleost CD4-1 sequences. The expression pattern of CD4-2A and CD4-2B mRNA during the embryonic development followed the trend of an initial increase after fertilized, providing evidence of maternal transfer of CD4-2 homologues to the developing cobia embryos and larvae. All of these results are useful for better understanding of cell-mediated immunity of cobia. Highlights: The first report on the possible soluble CD4 in cobia. Two CD4-2 molecules have been identified and exhibited 16.10% amino acids identity with each other. The results confirmed a maternal transfer of CD4-2 homologues to cobia embryos and larvae.