Tespa1 protein is phosphorylated in response to store-operated calcium entry

The Lung Adenocarcinoma Microenvironment Mining and Its Prognostic Merit

Background:

As a common pathological type of lung cancer, lung adenocarcinoma (LUAD) is mainly treated by surgery, chemotherapy, targeted therapy and radiotherapy. Although a relatively mature treatment system has been established, there are few studies on the microenvironment of LUAD.

Material and Methods:

The immune and stromal scores of patients from the LUAD cohort in the TCGA database were obtained by using ESTIMATE. The relationship of immune and stromal scores with the clinicopathological characteristics and overall survival of LUAD patients was assessed by R. GO, KEGG and Cox regression analyses were employed to analyze intersecting genes and to identify reliable prognostic markers. The identified genes were also analyzed in the GEPIA database to assess their correlations with survival, and these relationships were verified with the Kaplan-Meier Plotter database.

Results:

The immune score was related to the survival time and tumor topography of LUAD patients. There was a significant correlation between stromal score and tumor metastasis. Through multivariate analysis, stage (HR = 1.640, 95% CI = 1.019-2.642, P = 0.042) and risk score (HR = 1.036, 95% CI = 1.026-1.046, P < 0.001). The genes (ARHGAP15, BTLA, CASS4, CLECL1, FAM129C, STAP1, TESPA1, and S100P) showed credible prognostic value in LUAD patients in TCGA through GEPIA database online analysis and verification in the Kaplan-Meier plotter database.

Conclusions:

In the microenvironment of lung adenocarcinoma, the differentially expressed genes screened by immune score and stromal score have certain value in evaluating the survival/prognosis of patients, as well as the invasion and progression of tumors.

Thymocyte selection: From signaling to epigenetic regulation

During thymocyte development at the double positive stage, thymocytes are subjected to a TCR quality check process termed "thymocyte selection." TCRs with proper binding capabilities to MHC molecules (with self-peptide) are able to transduce cell survival signals and allow the continuing of development to single positive T cells. It has been known that TCRs in DP cells can transduce signals with higher efficiency than peripheral mature T cells, even though they share most of the signaling components. Recent studies have revealed some thymocyte-specific signaling modulators including Themis and Tespa1. The activation of TCR signaling during positive selection results in the activation of several key transcription factors and extensive gene expression change, which has been revealed by newly developed systemic transcriptome analysis tools, and could be used for the evaluation of positive selection process. The fate determination postpositive selection is also governed on the epigenetic level including both DNA methylation and histone modifications.

TCR Signal Strength and T Cell Development

Thymocyte selection involves the positive and negative selection of the repertoire of T cell receptors (TCRs) such that the organism does not suffer autoimmunity, yet has the benefit of the ability to recognize any invading pathogen. The signal transduced through the TCR is translated into a number of different signaling cascades that result in transcription factor activity in the nucleus and changes to the cytoskeleton and motility. Negative selection involves inducing apoptosis in thymocytes that express strongly self-reactive TCRs, whereas positive selection must induce survival and differentiation programs in cells that are more weakly self-reactive. The TCR recognition event is analog by nature, but the outcome of signaling is not. A large number of molecules regulate the strength of the TCR-derived signal at various points in the cascades. This review discusses the various factors that can regulate the strength of the TCR signal during thymocyte development.

Tespa1 negatively regulates FcεRI-mediated signaling and the mast cell-mediated allergic response

Antigen-mediated cross-linking of IgE on mast cells triggers a signaling cascade that results in their degranulation and proinflammatory cytokine production, which are key effectors in allergic reactions. We show that the activation of mast cells is negatively regulated by the newly identified adaptor protein Tespa1. Loss of Tespa1 in mouse mast cells led to hyper-responsiveness to stimulation via FcεRI. Mice lacking Tespa1 also displayed increased sensitivity to IgE-mediated allergic responses. The dysregulated signaling in KO mast cells was associated with increased activation of Grb2-PLC-γ1-SLP-76 signaling within the LAT1 (linker for activation of T cells family, member 1) signalosome versus the LAT2 signalosome. Collectively, these findings show that Tespa1 orchestrates mast cell activation by tuning the balance of LAT1 and LAT2 signalosome assembly.

Fine-tuning T cell receptor signaling to control T cell development

T cell development from immature CD4(+)CD8(+) double-positive (DP) thymocytes to the mature CD4 or CD8 single-positive (SP) stage requires proper T cell receptor (TCR) signaling. The current working model of thymocyte development is that the strength of the TCR-mediated signal - from little-or-none, through intermediate, to strong - received by the immature cells determines whether they will undergo death by neglect, positive selection, or negative selection, respectively. In recent years, several developmentally regulated, stage-specifically expressed proteins and miRNAs have been found that act like fine-tuners for signal transduction and propagation downstream of the TCR. This allows them to govern thymocyte positive selection. Here, we summarize recent findings on these molecules and suggest new concepts of TCR positive-selection signaling.