Recruitment of Sprouty1 to immune synapse regulates T cell receptor signaling.
TCR stimulation not only initiates positive signals for T cell activation, but also induces negative signals that down-regulate T cells. We previously reported that Sprouty1, a negative regulator of Ras-MAPK pathway of receptor tyrosine kinases, was induced by TCR signal and inhibited TCR signaling in CD4+ T cell clones. In this study, we addressed the mechanism underlying Sprouty1 inhibition of T cells. When overexpressed in Jurkat T cells, Sprouty1 inhibited TCR signal-induced IL-2 transcription, and also AP-1, NFAT, and NF-kappaB activation, which suggests that Sprouty1 acts at proximal TCR signalosome. Accordingly, we found that Sprouty1 translocated to immune synapse upon TCR engagement in both Jurkat cells and activated primary T cells and interacted with various signaling molecules in the TCR signalosome, such as linker for activation of T cells (LAT), phospholipase C-gamma1 (PLC-gamma1), c-Cbl/Cbl-b, and HPK1. Sprouty1 inhibited LAT phosphorylation, leading to decreased MAPK activation and IL-2 production. Deletion of C-terminal 54 amino acids in Sprouty1 abolished its inhibitory effect and this deletion mutant was unable to translocate to immune synapse and interact with LAT. Overall, our data suggest that Sprouty1 induced by TCR signal negatively regulates further TCR signaling by interacting with proximal signaling molecules in immune synapse, providing a novel regulatory mechanism of T cells.
Lee
Jun Sung
JS
Specific Organs Cancer Branch Research Institute National Cancer Center, Gyeonggi-do, Korea.
Lee
Ji Eun
JE
Oh
Yu Mi
YM
Park
Jong Bae
JB
Choi
Heonsik
H
Choi
Chung Yeon
CY
Kim
In-Hoo
IH
Lee
Seung Hoon
SH
Choi
Kyungho
K
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D015153:Blotting, Western; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D054992:Immunological Synapses / Q000276:immunology* / Q000378:metabolism; D047468:Immunoprecipitation; D007376:Interleukin-2 / Q000096:biosynthesis; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000276:immunology; D008565:Membrane Proteins / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D010750:Phosphoproteins / Q000276:immunology* / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D007376:Interleukin-2; C110810:LAT protein, human; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; C486055:SPRY1 protein, human