Identification of cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) isoforms in the Pekin duck.
Cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4, CD152) is an inhibitory T cell receptor predominately expressed on activated T cells. The duck CTLA-4 (DuCTLA-4) cDNA and a transcript lacking the predicted transmembrane encoding region (DuCTLA-4DeltaTM) were isolated from splenocytes using RT-PCR. The predicted DuCTLA-4 protein showed an identity of 92%, 49% and 47% with chicken, human and mouse homologues, respectively. Sequence comparison revealed conservation of residues implicated in the B7 ligand binding, disulfide linkages, glycosylation and intracellular signaling. DuCTLA-4 mRNA was predominately expressed in primary and secondary immune organs. DuCTLA-4 and DuCTLA-4DeltaTM transcripts were differentially regulated in PBMCs. Flow cytometric analysis showed constitutive expression of DuCTLA-4 protein on freshly isolated PBMCs and a modest increase upon mitogen stimulation. Our observations suggest that DuCTLA-4 and its isoform DuCTLA-4DeltaTM evolved before the divergence of birds and mammals. Both DuCTLA-4 isoforms have significant structural homology to mammalian CTLA-4 proteins but their individual roles in the regulation of duck immune responses remains to be elucidated.
Yao
Qingxia
Q
Division of Gastroenterology, Department of Medicine, University of Alberta, 130 University Campus, Edmonton, Alberta, Canada.
Fischer
Karl P
KP
Motyka
Bruce
B
Ferland
Sean
S
Li
Lena
L
Tyrrell
D Lorne
DL
Gutfreund
Klaus S
KS
D056704:Adaptive Immunity / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D001483:Base Sequence; D060908:CTLA-4 Antigen; D003001:Cloning, Molecular; D004372:Ducks / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D015703:Antigens, CD; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C556707:Ctla4 protein, mouse; D020033:Protein Isoforms; D012333:RNA, Messenger; D011994:Recombinant Proteins