Nonsense CD247 mutations show dominant-negative features in T-cell receptor expression and function - 03/10/24
Graphical abstract |
Abstract |
Background |
The invariant TCR ζ/CD247 homodimer is crucial for TCR/CD3 expression and signaling through its 3 immunoreceptor tyrosine-based activation motifs (ITAMs). Homozygous null mutations in CD247 lead to immunodeficiency, while carriers exhibit 50% reduced surface CD3. It is unclear whether carriers of other CD247 variants show dominant-negative effects.
Objective |
We sought to analyze and model the potential impact on T-cell receptor (TCR) expression and function of heterozygous nonsense CD247 mutations found in patients with signs of immunodeficiency or autoimmunity.
Methods |
Jurkat T cells, either wild-type (WT) or CRISPR/Cas9-edited CD247-deficient (ZKO), were lentivirally transduced with WT CD247 or mutations ablating 1 (Q142X), 2 (Q101X), or 3 (Q70X) ITAMs.
Results |
Three patients from unrelated families were studied. Two heterozygous nonsense CD247 mutations were identified (p.Y152X and p.Q101X), which affected ITAM-3 and ITAM-2 and ITAM-3, respectively. Both mutations were associated with low surface CD3 expression and normal intracellular CD247 levels using a transmembrane-specific antibody, but very low intracellular CD247 levels using an ITAM-3–specific one, suggesting the presence of truncated variants in T cells. Transduction of the mutations lacking 1, 2, or 3 ITAMs into ZKO cells could not restore normal surface CD3 expression (only 60%, 22%, and 10%, respectively), whereas in WT cells, normal surface CD3 expression was reduced (to 39%, 19%, and 9% of normal levels), and both effects were dependent on ITAM number. All 6 transfectants showed reduced CD69 induction (25% to 50%), indicating that they were unable to signal downstream properly, neither isolated nor associated with WT CD247.
Conclusions |
Our results suggest that CD247 variants lacking ITAMs due to nonsense, but not null, mutations are defective for normal TCR assembly and exert a dominant-negative effect on TCR expression and signaling in vitro. This, in turn, may correlate with clinical features in vivo.
Le texte complet de cet article est disponible en PDF.Key words : CD247, TCR ζ, CD3ζ, TCR, ITAM, immunodeficiency, autoimmunity
Abbreviations used : crRNA, iCD247, ITAM, NK, PHA-L, SCID, SEE, tracrRNA, TCR, TEMRA, WT
Plan
Vol 154 - N° 4
P. 1022-1032 - octobre 2024 Retour au numéro
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