title: Molecular characterization and expression analysis during embryo development of CD4-1 homologue in large yellow croaker Larimichthys crocea.
abstract: CD4+helper T (Th) cells are a master component of the adaptive immune response. CD4 is one of the most effective surface markers for identifying Th cells. In the present study, we cloned and characterized a CD4-1 homologue, LycCD4-1, from large yellow croaker Larimichthys crocea. The full-length cDNA of LycCD4-1 is 1695 bp long, encoding a protein of 462 amino acids. The deduced LycCD4-1 protein has a typical domain architecture as found in mammalian CD4 molecules, including a signal peptide, four extracellular immunoglobulin-like (Ig-like) domains, a transmembrane region, and a CXC signaling motif in the cytoplasmic tail. Four N-glycosylation sites and 10 cysteine residues were also found in LycCD4-1, which may be essential for its tertiary structure and succeeding function. Homology comparison showed that LycCD4-1 has 27.9-58.4% identity to other teleost fish CD4-1 molecules, and 16.4-20% identity to those of higher vertebrates. Genomic analysis revealed that the LycCD4-1 gene consisted of nine exons and eight introns and exhibited a similar exon-intron organization to other species CD4 genes except for a different intron length. Phylogenetic analysis showed that LycCD4-1 form a cluster with CD4-1 molecules in other fish species. The LycCD4-1 was constitutively expressed in all tissues tested, with a higher expression in gills and spleen. LycCD4-1 mRNA expression in the spleen and head kidney tissue was increased by poly (I:C) at 48 h, whereas its expression levels were somewhat down-regulated at 6 h and 72 h after bacterial vaccine induction in spleen. Unexpectedly, LycCD4-1 mRNA could be detected in each stage of early embryo development since fertilized eggs, with a higher level before mid-gastrula and the highest level in high blastocysts. These results will be helpful for better understanding molecular characteristics of CD4-1 and tracing origin of CD4-1+cell precursors in fish.
authors.affiliation: Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, PR China; School of Life Sciences, Xiamen University, Xiamen 361005, PR China.
authors.forename: Kaiqiong
authors.initials: K
authors.lastname: Mao
authors.affiliation: Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, PR China; School of Life Sciences, Xiamen University, Xiamen 361005, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, PR China.
authors.forename: Yinnan
authors.initials: Y
authors.lastname: Mu
authors.affiliation: Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, PR China.
authors.forename: Jingqun
authors.initials: J
authors.lastname: Ao
authors.affiliation: Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, PR China; Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources, Xiamen 361005, PR China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, PR China. Electronic address: chenxinhua@tio.org.cn.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015704:CD4 Antigens / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000276:immunology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D010473:Perciformes / Q000196:embryology / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment / Q000662:veterinary; D014018:Tissue Distribution
chemical_list: D015704:CD4 Antigens; D018076:DNA, Complementary; D029941:Fish Proteins; D012333:RNA, Messenger
keywords: CD4-1; Embryo development; Expression pattern; Large yellow croaker (Larimichthys crocea)