TIM-3 Suppresses Anti-CD3/CD28-Induced TCR Activation and IL-2 Expression through the NFAT Signaling Pathway.
TIM-3 (T cell immunoglobulin and mucin-domain containing protein 3) is a member of the TIM family of proteins that is preferentially expressed on Th1 polarized CD4+ and CD8+ T cells. Recent studies indicate that TIM-3 serves as a negative regulator of T cell function (i.e. T cell dependent immune responses, proliferation, tolerance, and exhaustion). Despite having no recognizable inhibitory signaling motifs, the intracellular tail of TIM-3 is apparently indispensable for function. Specifically, the conserved residues Y265/Y272 and surrounding amino acids appear to be critical for function. Mechanistically, several studies suggest that TIM-3 can associate with interleukin inducible T cell kinase (ITK), the Src kinases Fyn and Lck, and the p85 phosphatidylinositol 3-kinase (PI3K) adaptor protein to positively or negatively regulate IL-2 production via NF-κB/NFAT signaling pathways. To begin to address this discrepancy, we examined the effect of TIM-3 in two model systems. First, we generated several Jurkat T cell lines stably expressing human TIM-3 or murine CD28-ECD/human TIM-3 intracellular tail chimeras and examined the effects that TIM-3 exerts on T cell Receptor (TCR)-mediated activation, cytokine secretion, promoter activity, and protein kinase association. In this model, our results demonstrate that TIM-3 inhibits several TCR-mediated phenotypes: i) NF-kB/NFAT activation, ii) CD69 expression, and iii) suppression of IL-2 secretion. To confirm our Jurkat cell observations we developed a primary human CD8+ cell system that expresses endogenous levels of TIM-3. Upon TCR ligation, we observed the loss of NFAT reporter activity and IL-2 secretion, and identified the association of Src kinase Lck, and PLC-γ with TIM-3. Taken together, our results support the conclusion that TIM-3 is a negative regulator of TCR-function by attenuating activation signals mediated by CD3/CD28 co-stimulation.
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Brian
B
Tomkowicz
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Eileen
E
Walsh
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Adam
A
Cotty
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Raluca
R
Verona
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Nina
N
Sabins
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Fred
F
Kaplan
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Sandy
S
Santulli-Marotto
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Chen-Ni
CN
Chin
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Jill
J
Mooney
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Russell B
RB
Lingham
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Michael
M
Naso
Janssen BioTherapeutics, 1400 McKean Road, Spring House, PA 19477, United States of America.
Timothy
T
McCabe
D015703:Antigens, CD / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D017930:Genes, Reporter; D000072597:Hepatitis A Virus Cellular Receptor 2; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000276:immunology; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D017434:Protein Structure, Tertiary; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism
D015703:Antigens, CD; D016207:Cytokines; C448908:HAVCR2 protein, human; D000072597:Hepatitis A Virus Cellular Receptor 2; D007376:Interleukin-2; D008565:Membrane Proteins; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D011948:Receptors, Antigen, T-Cell; D002118:Calcium