biostudies-literatureZhang FAgence Nationale de la RechercheNational Discipline Innovation and Intelligence Introduction Base 111 ProjectInvestissement d’Avenir program ProFiNational Natural Science Foundation of ChinaPHENOMINInstitut National de la Santé et de la Recherche MédicaleAix-Marseille UniversitéEuropean Research CouncilHenan ProvinceInvestissement d'Avenir program ProFiCentre National de la Recherche ScientifiqueDCBIOLMSDAvenire20250339https://www.ebi.ac.uk/biostudies/studies/S-EPMC12097149biostudies-literatureUnknown222(8)Naive T cell activation requires both TCR and CD28 signals. The CARMIL2 cytosolic protein enables CD28-dependent activation of the NF-κB transcription factor via its ability to link CD28 to the CARD11 adaptor protein. Here, we developed mice expressing a mutation named Carmil2QE and mimicking a mutation found in human T cell malignancies. Naive T cells from Carmil2QE mice contained preformed CARMIL2QE-CARD11 complexes in numbers comparable to those assembling in wild-type T cells after CD28 engagement. Such ready-made CARMIL2QE-CARD11 complexes also formed in CD28-deficient mice where they unexpectedly induced most of the functions that normally result from CD28 engagement in a manner that remains antigen-dependent. In turn, tumor-specific T cells expressing Carmil2QE do not require CD28 eThe Journal of experimental medicineA CARMIL2 gain-of-function mutation suffices to trigger most CD28 costimulatory functions in vivo.PMC12097149ANR-10-INBS-0732170879ANR-10-INBS-08D20036U1904157C2418532070898787300ANR-AAP-2021 Carmil2 21-CE15-0034-02ANR-AAP-2018 Super-Basilic 18-CE15-0021-0132000627Zhang FRoncagalli RLiang YVoisinne GVilarnau Wolek CZhang LMori DMalissen BBurlet-Schiltz OGelard LLu LMellado VMalissen MFiore FCelis-Gutierrez JMello MPanigot SGonzalez de Peredo AfalseA CARMIL2 gain-of-function mutation suffices to trigger most CD28 costimulatory functions in vivo.Naive T cell activation requires both TCR and CD28 signals. The CARMIL2 cytosolic protein enables CD28-dependent activation of the NF-κB transcription factor via its ability to link CD28 to the CARD11 adaptor protein. Here, we developed mice expressing a mutation named Carmil2QE and mimicking a mutation found in human T cell malignancies. Naive T cells from Carmil2QE mice contained preformed CARMIL2QE-CARD11 complexes in numbers comparable to those assembling in wild-type T cells after CD28 engagement. Such ready-made CARMIL2QE-CARD11 complexes also formed in CD28-deficient mice where they unexpectedly induced most of the functions that normally result from CD28 engagement in a manner that remains antigen-dependent. In turn, tumor-specific T cells expressing Carmil2QE do not require CD28 e2025-01-01T00:00:00Z2025 Aug2026-06-02T20:45:29.515Z2025-08-12T03:04:49.515ZS-EPMC120971494040214910.1084/jem.20250339