%0 Journal Article
%T Nonsense CD247 mutations show dominant-negative features in T-cell receptor expression and function.
%A Briones AC
%A Megino RF
%A Marin AV
%A Chacón-Arguedas D
%A García-Martinez E
%A Balastegui-Martín H
%A Reyburn HT
%A Henrickson SE
%A Rodríguez-Sainz C
%A Seoane-Reula E
%A Sanchez-Mateos P
%A Cardenas PP
%A Regueiro JR
%J J Allergy Clin Immunol
%V 0
%N 0
%D 2024 Jul 9
%M 38992472
%F 14.29
%R 10.1016/j.jaci.2024.06.019
%X <B>BACKGROUND: </B>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.<BR><B>OBJECTIVE: </B>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.<BR><B>METHODS: </B>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.<BR><B>RESULTS: </B>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.<BR><B>CONCLUSIONS: </B>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.