Key Points
Ubc9 interacts with and SUMOylates the immune adaptor SLP-76 in T cells.
Synergy of SLP-76–Ubc9 on IL-2 transcription is SLP-76 SUMOylation dependent.
SLP-76 SUMOylation is required for Ubc9-NFAT complex assembly for IL-2 transcription.
Visual Abstract
Abstract
Although the immune adaptor SH2 domain containing leukocyte phosphoprotein of 76 kDa (SLP-76) integrates and propagates the TCR signaling, the regulation of SLP-76 during the TCR signaling is incompletely studied. In this article, we report that SLP-76 interacts with the small ubiquitin-like modifier (SUMO) E2 conjugase Ubc9 and is a substrate for Ubc9-mediated SUMOylation in human and mouse T cells. TCR stimulation promotes SLP-76–Ubc9 binding, accompanied by an increase in SLP-76 SUMOylation. Ubc9 binds to the extreme C terminus of SLP-76 spanning residues 516–533 and SUMOylates SLP-76 at two conserved residues K266 and K284. In addition, SLP-76 and Ubc9 synergizes to augment the TCR-mediated IL-2 transcription by NFAT in a manner dependent of SUMOylation of SLP-76. Moreover, although not affecting the TCR proximal signaling events, the Ubc9-mediated SUMOylation of SLP-76 is required for TCR-induced assembly of Ubc9-NFAT complex for IL-2 transcription. Together, these results suggest that Ubc9 modulates the function of SLP-76 in T cell activation both by direct interaction and by SUMOylation of SLP-76 and that the Ubc9–SLP-76 module acts as a novel regulatory complex in the control of T cell activation.
Footnotes
This work was supported by grants from the National Natural Science Foundation of China (31470840 to H.L.) and the Suzhou Key Program Special Fund (KSF-E-30 to H.L.).
The online version of this article contains supplemental material.
Abbreviations used in this article:
- ADAP
- adhesion and degranulation-promoting adapter protein
- ChIP
- chromatin immunoprecipitation
- GADS
- Grb2-related adaptor downstream of Shc
- HA
- hemagglutinin
- LC-MS/MS
- liquid chromatography–tandem mass spectrometry
- PLCγ1
- phospholipase Cγ1
- PRR
- proline-rich region
- RanGAP1
- Ran GTPase activating protein 1
- SKAP1
- src kinase associated phosphoprotein 1
- SLP-76
- SH2 domain containing leukocyte phosphoprotein of 76 kDa
- SUMO
- small ubiquitin-like modifier
- WT
- wild type.
- Received May 14, 2019.
- Accepted September 30, 2019.
- Copyright © 2019 by The American Association of Immunologists, Inc.
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