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.
Division of Gastroenterology, Department of Medicine, University of Alberta, 130 University Campus, Edmonton, Alberta, Canada.
Qingxia
Q
Yao
Karl P
KP
Fischer
Bruce
B
Motyka
Sean
S
Ferland
Lena
L
Li
D Lorne
DL
Tyrrell
Klaus S
KS
Gutfreund
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