Genomic organization and expression of CD8alpha and CD8beta genes in fugu Takifugu rubripes.
We have cloned cDNAs encoding the alpha and beta chains of CD8 from the tiger pufferfish (fugu), Takifugu rubripes. The cDNA sequences encode a putative leader peptide, extracellular immunoglobulin variable region-like domain, stalk region, transmembrane region, and cytoplasmic tail. A protein tyrosine kinase p56lck binding motif was not found in the putative fugu CD8alpha cytoplasmic tail. O-linked glycosylation sites were found in the stalk of both CD8 chains, suggesting possible stalk formation. Phylogenetic analysis showed that fugu CD8alpha and CD8beta chains cluster with other vertebrate CD8alpha and CD8beta chains, respectively. The fugu CD8 genes comprise six exons separated by five introns. The genes are tandemly aligned 3.6 kb apart and are in the same transcription orientation. Quantitative RT-PCR analysis demonstrated that fugu CD8 is expressed predominantly in lymphoid tissues. In situ hybridization showed that fugu CD8 genes are expressed in thymocytes and lymphocytes within lymphoid organs. Molecular characterization of CD8 in fish provides the basis for development of specific antibodies to identify T-cell subsets, as well as potentially important insights into the evolution of CD8 and the adaptive immunity.
Suetake
Hiroaki
H
Fisheries Laboratory, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Hamamatsu, Shizuoka 431-0214, Japan. asuetake@mail.ecc.u-tokyo.ac.jp
Araki
Kyosuke
K
Akatsu
Kanako
K
Somamoto
Tomonori
T
Dijkstra
Johannes Martinus
JM
Yoshiura
Yasutoshi
Y
Kikuchi
Kiyoshi
K
Suzuki
Yuzuru
Y
D000595:Amino Acid Sequence; D000818:Animals; D016827:CD8 Antigens / Q000737:chemistry / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation; D023061:Gene Order; D016678:Genome / Q000235:genetics; D006801:Humans; D017403:In Situ Hybridization; D007668:Kidney / Q000502:physiology; D008214:Lymphocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D023741:Takifugu / Q000235:genetics* / Q000378:metabolism*
D016827:CD8 Antigens; C431698:CD8alpha antigen; C477867:CD8beta antigen; D018076:DNA, Complementary