Abstract
SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) is an adaptor protein that is essential for T cell development and T cell receptor (TCR) signaling activation. Previous studies have identified an important negative feedback regulation of SLP-76 by HPK1 (hematopoietic progenitor kinase 1; MAP4K1)-induced Ser-376 phosphorylation. Ser-376 phosphorylation of SLP-76 mediates 14-3-3 binding, resulting in the attenuation of SLP-76 activation and downstream signaling; however, the underlying mechanism of this action remains unknown. Here, we report that phosphorylated SLP-76 is ubiquitinated and targeted for proteasomal degradation during TCR signaling. SLP-76 ubiquitination is mediated by Ser-376 phosphorylation. Furthermore, Lys-30 is identified as a ubiquitination site of SLP-76. Loss of Lys-30 ubiquitination of SLP-76 results in enhanced anti-CD3 antibody-induced ERK and JNK activation. These results reveal a novel regulation mechanism of SLP-76 by ubiquitination and proteasomal degradation of activated SLP-76, which is mediated by Ser-376 phosphorylation, leading to down-regulation of TCR signaling.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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14-3-3 Proteins / genetics
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14-3-3 Proteins / immunology
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14-3-3 Proteins / metabolism
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Adaptor Proteins, Signal Transducing / genetics
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Adaptor Proteins, Signal Transducing / immunology
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Adaptor Proteins, Signal Transducing / metabolism*
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Animals
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Enzyme Activation / physiology
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Extracellular Signal-Regulated MAP Kinases / genetics
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Extracellular Signal-Regulated MAP Kinases / immunology
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Extracellular Signal-Regulated MAP Kinases / metabolism
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Humans
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Jurkat Cells
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MAP Kinase Kinase 4 / genetics
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MAP Kinase Kinase 4 / immunology
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MAP Kinase Kinase 4 / metabolism
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Mice
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Mice, Mutant Strains
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Phosphoproteins / genetics
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Phosphoproteins / immunology
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Phosphoproteins / metabolism*
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Phosphorylation / physiology
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Proteasome Endopeptidase Complex / genetics
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Proteasome Endopeptidase Complex / immunology
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Proteasome Endopeptidase Complex / metabolism
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Proteolysis*
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Receptors, Antigen, T-Cell / genetics
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Receptors, Antigen, T-Cell / immunology
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Receptors, Antigen, T-Cell / metabolism*
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Serine / genetics
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Serine / immunology
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Serine / metabolism
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Signal Transduction / physiology*
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Ubiquitination / physiology*
Substances
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14-3-3 Proteins
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Adaptor Proteins, Signal Transducing
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Phosphoproteins
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Receptors, Antigen, T-Cell
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SLP-76 signal Transducing adaptor proteins
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Serine
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Extracellular Signal-Regulated MAP Kinases
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MAP Kinase Kinase 4
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Proteasome Endopeptidase Complex