TY - JOUR

T1 - The role of the different CD3γ domains in TCR expression and signaling

AU - Garcillán, Beatriz

AU - Megino, Rebeca F.

AU - Herrero-Alonso, Marta

AU - Guardo, Alberto C.

AU - Perez-Flores, Veronica

AU - Juraske, Claudia

AU - Idstein, Vincent

AU - Martin-Fernandez, Jose M.

AU - Geisler, Carsten

AU - Schamel, Wolfgang W.A.

AU - Marin, Ana V.

AU - Regueiro, Jose R.

N1 - Publisher Copyright: Copyright © 2022 Garcillán, Megino, Herrero-Alonso, Guardo, Perez-Flores, Juraske, Idstein, Martin-Fernandez, Geisler, Schamel, Marin and Regueiro.

PY - 2022

Y1 - 2022

N2 - The CD3 subunits of the T-cell antigen receptor (TCR) play a central role in regulation of surface TCR expression levels. Humans who lack CD3γ (γ—) show reduced surface TCR expression levels and abolished phorbol ester (PMA)-induced TCR down-regulation. The response to PMA is mediated by a double leucine motif in the intracellular (IC) domain of CD3γ. However, the molecular cause of the reduced TCR surface expression in γ— lymphocytes is still not known. We used retroviral vectors carrying wild type CD3γ or CD3δ or the following chimeras (EC-extracellular, TM-transmembrane and IC): δECγTMγIC (δγγ for short), γγδ, γδδ and γγ-. Expression of γγγ, γγδ, γδδ or γγ- in the γ— T cell line JGN, which lacks surface TCR, demonstrated that cell surface TCR levels in JGN were dependent on the EC domain of CD3γ and could not be replaced by the one of CD3δ. In JGN and primary γ— patient T cells, the tested chimeras confirmed that the response to PMA maps to the IC domain of CD3γ. Since protein homology explains these results better than domain structure, we conclude that CD3γ contributes conformational cues that improve surface TCR expression, likely at the assembly or membrane transport steps. In JGN cells all chimeric TCRs were signalling competent. However, an IC domain at CD3γ was required for TCR-induced IL-2 and TNF-α production and CD69 expression, indicating that a TCR without a CD3γ IC domain has altered signalling capabilities.

AB - The CD3 subunits of the T-cell antigen receptor (TCR) play a central role in regulation of surface TCR expression levels. Humans who lack CD3γ (γ—) show reduced surface TCR expression levels and abolished phorbol ester (PMA)-induced TCR down-regulation. The response to PMA is mediated by a double leucine motif in the intracellular (IC) domain of CD3γ. However, the molecular cause of the reduced TCR surface expression in γ— lymphocytes is still not known. We used retroviral vectors carrying wild type CD3γ or CD3δ or the following chimeras (EC-extracellular, TM-transmembrane and IC): δECγTMγIC (δγγ for short), γγδ, γδδ and γγ-. Expression of γγγ, γγδ, γδδ or γγ- in the γ— T cell line JGN, which lacks surface TCR, demonstrated that cell surface TCR levels in JGN were dependent on the EC domain of CD3γ and could not be replaced by the one of CD3δ. In JGN and primary γ— patient T cells, the tested chimeras confirmed that the response to PMA maps to the IC domain of CD3γ. Since protein homology explains these results better than domain structure, we conclude that CD3γ contributes conformational cues that improve surface TCR expression, likely at the assembly or membrane transport steps. In JGN cells all chimeric TCRs were signalling competent. However, an IC domain at CD3γ was required for TCR-induced IL-2 and TNF-α production and CD69 expression, indicating that a TCR without a CD3γ IC domain has altered signalling capabilities.

KW - CD3 chimeras

KW - CD3γ

KW - CD3δ

KW - domains

KW - T cell receptor

U2 - 10.3389/fimmu.2022.978658

DO - 10.3389/fimmu.2022.978658

M3 - Journal article

C2 - 36119034

AN - SCOPUS:85138186960

VL - 13

JO - Frontiers in Immunology

JF - Frontiers in Immunology

SN - 1664-3224

M1 - 978658

ER -