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T cell receptor for antigen induces linker for activation of T cell-dependent activation of a negative signaling complex involving Dok-2, SHIP-1, and Grb-2.

ABSTRACT: Adaptor proteins positively or negatively regulate the T cell receptor for antigen (TCR) signaling cascade. We report that after TCR stimulation, the inhibitory adaptor downstream of kinase (Dok)-2 and its homologue Dok-1 are involved in a multimolecular complex including the lipid phosphatase Src homology 2 domain-containing inositol polyphosphate 5'-phosphatase (SHIP)-1 and Grb-2 which interacts with the membrane signaling scaffold linker for activation of T cells (LAT). Knockdown of LAT and SHIP-1 expression indicated that SHIP-1 favored recruitment of Dok-2 to LAT. Knockdown of Dok-2 and Dok-1 revealed their negative control on Akt and, unexpectedly, on Zap-70 activation. Our findings support the view that Dok-1 and -2 are critical elements of a LAT-dependent negative feedback loop that attenuates early TCR signal. Dok-1 and -2 may therefore exert a critical role in shaping the immune response and as gatekeepers for T cell tolerance.

SUBMITTER: Dong S

PROVIDER: S-EPMC2118126 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature

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T cell receptor for antigen induces linker for activation of T cell-dependent activation of a negative signaling complex involving Dok-2, SHIP-1, and Grb-2.

Dong Shen S Corre Béatrice B Foulon Eliane E Dufour Evelyne E Veillette André A Acuto Oreste O Michel Frédérique F

The Journal of experimental medicine 20061016 11

Adaptor proteins positively or negatively regulate the T cell receptor for antigen (TCR) signaling cascade. We report that after TCR stimulation, the inhibitory adaptor downstream of kinase (Dok)-2 and its homologue Dok-1 are involved in a multimolecular complex including the lipid phosphatase Src homology 2 domain-containing inositol polyphosphate 5'-phosphatase (SHIP)-1 and Grb-2 which interacts with the membrane signaling scaffold linker for activation of T cells (LAT). Knockdown of LAT and S ...[more]

PMID: 17043143

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Project description:OBJECTIVE:A widely recognized metabolic side effect of glucocorticoid (GC) therapy is steroid-induced diabetes mellitus (DM). However, studies on the molecular basis of GC-induced pancreatic beta cell dysfunction in human beta cells are lacking. The significance of non-coding RNAs in various cellular processes is emerging. In this study, we aimed to show the direct negative impact of GC on beta cell function and elucidate the role of riborepressor GAS5 lincRNA in the GC signaling pathway in human pancreatic beta cells. METHODS:Patients undergoing two weeks of high-dose prednisolone therapy were monitored for C-peptide levels. Human pancreatic islets and the human beta cell line EndoC-?H1 were incubated in pharmacological concentrations of dexamethasone. The GAS5 level was modulated using anti-sense LNA gapmeR or short oligonucleotides with GAS5 HREM (hormone response element motif). Immunoblotting and/or real-time PCR were used to assess changes in protein and RNA expression, respectively. Functional characterization included glucose-stimulated insulin secretion and apoptosis assays. Correlation analysis was performed on RNAseq data of human pancreatic islets. RESULTS:We found reduced C-peptide levels in patients undergoing high-dose GC therapy. Human islets and the human beta cell line EndoC-?H1 exposed to GC exhibited reduced insulin secretion and increased apoptosis. Concomitantly, reduced expression of important beta cell transcription factors, PDX1 and NKX6-1, as well as exocytotic protein SYT13 were observed. The expression of the glucocorticoid receptor was decreased, while that of serum and glucocorticoid-regulated kinase 1 (SGK1) was elevated. The expression of these genes was found to significantly correlate with GAS5 in human islet transcriptomics data. Increasing GAS5 levels using GAS5 HREM alleviated the inhibitory effects of dexamethasone on insulin secretion. CONCLUSIONS:The direct adverse effect of glucocorticoid in human beta cell function is mediated via important beta cell proteins and components of the GC signaling pathway in an intricate interplay with GAS5 lincRNA, a potentially novel therapeutic target to counter GC-mediated beta cell dysfunction.

Dataset Information

T cell receptor for antigen induces linker for activation of T cell-dependent activation of a negative signaling complex involving Dok-2, SHIP-1, and Grb-2.

Publications

T cell receptor for antigen induces linker for activation of T cell-dependent activation of a negative signaling complex involving Dok-2, SHIP-1, and Grb-2.

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