Mutation in splicing consensus sequences causes lack of TCR membrane expression due to exon excision.
T-cell antigen receptor (TCR) membrane-negative T-cell mutants can be divided into two groups: 1) those which lack one of the six TCR polypeptides and 2) those which contain a mutated TCR chain. The present experiments reveal a new mechanism for the development of TCR membrane-negative T-cell variants: mutations in splicing consensus motifs causing excision or misreading of an entire exon (exon 3 of the TCRAC or TCRBC genes). C27.15 cells transcribe a TCR alpha chain consisting of TCRAVJCexon1Cexon2-encoded amino acids plus six new amino acids. The assembly defect seems to be that the truncated alpha chain does not interact with CD3 delta molecules; consequently, no TCR alphabeta/CD3 deltaepsilongammaepsilon complexes are formed. E6.E12 cells transcribe a TCR beta chain composed of TCRBVDJCexon1Cexon2-encoded amino acids plus twenty-seven new amino acids, which seem not to form a transmembrane region. The truncated beta chain does associate with CD3 gammaepsilon heterodimers, yet no TCR alphabeta/CD3 deltaepsilongammaepsilon complexes are made. This may be due either to low assembly of TCR beta/CD3 gammaepsilon trimers or to lack of access of the mutated TCR beta/CD3 gammaepsilon trimers to the TCR alpha/CD3 deltaepsilon compartment in the endoplasmic reticulum.
Arnaud
J
J
Laboratoire d'Immunologie Cellulaire et Moléculaire, Centre d' Immunopathologie et de Génétique Humaine, CNRS UPR 8291, CHU de PURPAN, 31300 Toulouse, France.
Cayrou
C
C
Llobera
R
R
Rubin
B
B
D000595:Amino Acid Sequence; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism*; D016384:Consensus Sequence; D005091:Exons; D005434:Flow Cytometry; D005796:Genes; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics; D008969:Molecular Sequence Data; D017354:Point Mutation; D012326:RNA Splicing; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D014407:Tumor Cells, Cultured
D008562:Membrane Glycoproteins; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta