IRAP-dependent endosomal T cell receptor signalling is essential for T cell responses

Irini Evnouchidou (1, 2) , Pascal Chappert (2, 3) , Samira Benadda (1) , Andrés Ernesto Zucchetti (4) , Mirjana Weimershaus (1) , Marcelle Bens (1) , Vivien Caillens (1) , Despoina Koumantou (1) , Sophie Lotersztajn (1) , Peter Van van Endert (3) , J. Davoust (5, 3) , Pierre Guermonprez (1, 6) , Claire Hivroz (4) , David Alexandre Gross (1, 7) , Loredana Saveanu (1)

1 CRI (UMR_S_1149 / ERL_8252 / U1149) - Centre de recherche sur l'Inflammation
2 Inovarion [Paris]
3 INEM - UM 111 (UMR 8253 / U1151) - Institut Necker Enfants-Malades
4 U932 - Immunité et cancer
5 END-ICAP - Handicap neuromusculaire : Physiopathologie, Biothérapie et Pharmacologies appliquées
6 King‘s College London
7 INTEGRARE - Approches génétiques intégrées et nouvelles thérapies pour les maladies rares

T cell receptor (TCR) activation is modulated by mechanisms such as TCR endocytosis, which is thought to terminate TCR signalling. Here we show that, upon internalization, TCR continues to signal from a set of specialized endosomes that are crucial for T cell functions. Mechanistically, TCR ligation leads to clathrin-mediated internalization of the TCR-CD3ζ complex, while maintaining CD3ζ signalling, in endosomal vesicles that contain the insulin responsive aminopeptidase (IRAP) and the SNARE protein Syntaxin 6. Destabilization of this compartment through IRAP deletion enhances plasma membrane expression of the TCR-CD3ζ complex, yet compromises overall CD3ζ signalling; moreover, the integrity of this compartment is also crucial for T cell activation and survival after suboptimal TCR activation, as mice engineered with a T cell-specific deletion of IRAP fail to develop efficient polyclonal anti-tumour responses. Our results thus reveal a previously unappreciated function of IRAP-dependent endosomal TCR signalling in T cell activation.

Domaines: Immunité adaptative

Irini Evnouchidou, Pascal Chappert, Samira Benadda, Andrés Ernesto Zucchetti, Mirjana Weimershaus, et al.. IRAP-dependent endosomal T cell receptor signalling is essential for T cell responses. Nature Communications, 2020, 11 (1), pp.2779. ⟨10.1038/s41467-020-16471-7⟩. ⟨hal-02867476⟩