Project description:Transforming growth factor-beta (TGF-β) restrains cytotoxic immune response to maintain self-tolerance and to promote tumor immune evasion. Yet how SMAD4, a central transcription factor component of TGF-β signaling, regulates CD8+ T cell function remains unclear. Here we have demonstrated SMAD4 played a critical role in promoting CD8+ T cell activation and cytotoxic function. SMAD4-mediated transcriptional regulation of CD8+ T cell activation and cytotoxicity is regulated by T-cell receptor (TCR) signaling pathway rather than TGF-β signaling pathway. We described a new mechanism that in TCR-mediated intracellular signal propagation, SMAD4 markedly translocated into the nucleus, upregulated genes that encoding TCR complex subunits and cytotoxic molecules in CD8+ T cells, reinforced the TCR-activation signals through a positive feedback loop. And in this signaling, SMAD4 is phosphorylated by ERK at Ser367 residue. Our study thus demonstrates an essential role of SMAD4 in promoting CD8+ T cell mediated cytotoxic immune responses.
Project description:Transforming growth factor-beta (TGF-β) restrains cytotoxic immune response to maintain self-tolerance and to promote tumor immune evasion. Yet how SMAD4, a central transcription factor component of TGF-β signaling, regulates CD8+ T cell function remains unclear. Here we have demonstrated SMAD4 played a critical role in promoting CD8+ T cell activation and cytotoxic function. SMAD4-mediated transcriptional regulation of CD8+ T cell activation and cytotoxicity is regulated by T-cell receptor (TCR) signaling pathway rather than TGF-β signaling pathway. We described a new mechanism that in TCR-mediated intracellular signal propagation, SMAD4 markedly translocated into the nucleus, upregulated genes that encoding TCR complex subunits and cytotoxic molecules in CD8+ T cells, reinforced the TCR-activation signals through a positive feedback loop. And in this signaling, SMAD4 is phosphorylated by ERK at Ser367 residue. Our study thus demonstrates an essential role of SMAD4 in promoting CD8+ T cell mediated cytotoxic immune responses.
Project description:SMAD4, a key mediator of TGF-beta signaling, plays a crucial role in T cells to prevent chronic intestinal inflammation through unknown mechanisms. We reveal that SMAD4 in CD8 T cells prevents chronic intestinal inflammation primarily in a TGF-beta-independent manner. Mechanistically, SMAD4, in CD8 T cells, acts as a basal and tonic repressor of TGF-beta-target genes at the transcriptional and epigenetic level, prior to any TGF-beta signal. SMAD4 deletion affects aberrantly a wide range of TGF-beta-target genes, thereby promoting accumulation and epithelial retention of CD8.alpha.beta T cells inversely to total TGF-beta signaling disruption. Moreover, SMAD4 deletion unleashes the expression of TGF-beta-signaling-repressors and hampers TGF-β-mediated CD8 T cell immunosuppression, eliciting their chronic activation. Hence, in a feedforward mechanism, SMAD4 both blocks the TGF-beta signature in CD8 T cells and pre-sensitizes them to TGF-beta.
Project description:SMAD4, a key mediator of TGF-beta signaling, plays a crucial role in T cells to prevent chronic intestinal inflammation through unknown mechanisms. We reveal that SMAD4 in CD8 T cells prevents chronic intestinal inflammation primarily in a TGF-beta-independent manner. Mechanistically, SMAD4, in CD8 T cells, acts as a basal and tonic repressor of TGF-beta-target genes at the transcriptional and epigenetic level, prior to any TGF-beta signal. SMAD4 deletion affects aberrantly a wide range of TGF-beta-target genes, thereby promoting accumulation and epithelial retention of CD8.alpha.beta T cells inversely to total TGF-beta signaling disruption. Moreover, SMAD4 deletion unleashes the expression of TGF-beta-signaling-repressors and hampers TGF-β-mediated CD8 T cell immunosuppression, eliciting their chronic activation. Hence, in a feedforward mechanism, SMAD4 both blocks the TGF-beta signature in CD8 T cells and pre-sensitizes them to TGF-beta.
Project description:We compared gene expression profiling between CD4+ helper T cells and CD8+ cytotoxic T cells CD4+ helper T cells vs CD8+ cytotoxic T cells
Project description:Although belonging to different branches of the immune system, cytotoxic CD8+ αβ T cells and γδ T cells utilize common cytolytic effectors including FasL, granzymes, perforin and granulysin. The effector proteins are stored in different subsets of lysosome-related effector vesicles (LREVs) and released to the immunological synapse upon target cell encounter. EVs of activated and expanded cytotoxic CD8+ αβ T cells or γδ T cells were enriched from culture supernatants by differential and ultracentrifugation and characterized by a comparative proteomic profiling with tandem mass tags (TMT10plex).
Project description:TGF-beta/Smads signaling plays important roles in vascular integrity. To identify potential Smad4 target genes in brain endothelial cells that control cerebrovascular integrity, the microarray assay was performed to compare the gene expression profiles of bEnd3 transfected with Smad4-siRNA and control-siRNA. bEnd3 cells were infected by Smad4-siRNA or control-siRNA retrovirus particles produced by PLAT-E packaging cells and selected by puromycin. The specific and control RNAi cells were used for RNA extraction and hybridization on Affymetrix microarrays. Two independent infections were performed and samples were pooled in order to obtain representative populations.