Tonic ubiquitylation controls T-cell receptor:CD3 complex expression during T-cell development.
Expression of the T-cell receptor (TCR):CD3 complex is tightly regulated during T-cell development. The mechanism and physiological role of this regulation are unclear. Here, we show that the TCR:CD3 complex is constitutively ubiquitylated in immature double positive (DP) thymocytes, but not mature single positive (SP) thymocytes or splenic T cells. This steady state, tonic CD3 monoubiquitylation is mediated by the CD3varepsilon proline-rich sequence, Lck, c-Cbl, and SLAP, which collectively trigger the dynamin-dependent downmodulation, lysosomal sequestration and degradation of surface TCR:CD3 complexes. Blocking this tonic ubiquitylation by mutating all the lysines in the CD3 cytoplasmic tails significantly upregulates TCR levels on DP thymocytes. Mimicking monoubiquitylation by expression of a CD3zeta-monoubiquitin (monoUb) fusion molecule significantly reduces TCR levels on immature thymocytes. Moreover, modulating CD3 ubiquitylation alters immunological synapse (IS) formation and Erk phosphorylation, thereby shifting the signalling threshold for positive and negative selection, and regulatory T-cell development. Thus, tonic TCR:CD3 ubiquitylation results in precise regulation of TCR expression on immature T cells, which is required to maintain the fidelity of T-cell development.
Department of Immunology, St Jude Children's Research Hospital, Memphis, TN, USA.
Haopeng
H
Wang
Jeff
J
Holst
Seng-Ryong
SR
Woo
Cliff
C
Guy
Matt
M
Bettini
Yao
Y
Wang
Aaron
A
Shafer
Mayumi
M
Naramura
Michaël
M
Mingueneau
Leonard L
LL
Dragone
Sandra M
SM
Hayes
Bernard
B
Malissen
Hamid
H
Band
Dario A A
DA
Vignali
D000595:Amino Acid Sequence; D000818:Animals; D034281:Dynamins / Q000378:metabolism; D005786:Gene Expression Regulation; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000737:chemistry / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D050721:Proto-Oncogene Proteins c-cbl / Q000378:metabolism; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D054875:Ubiquitination
D017260:Receptor-CD3 Complex, Antigen, T-Cell; D050721:Proto-Oncogene Proteins c-cbl; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D034281:Dynamins; D008239:Lysine