biostudies-literatureZinzow-Kramer WMNIA NIH HHSNIAMS NIH HHS671-683https://www.ebi.ac.uk/biostudies/studies/S-EPMC12917752biostudies-literatureUnknown6(9)T cells experience varying intensities of tonic or basal TCR signaling in response to self-peptides presented by MHC (self-pMHC) in vivo. We analyzed four subpopulations of mouse naive CD4⁺ cells that express different levels of Nur77-GFP and Ly6C, surrogate markers that positively and inversely correlate with the strength of tonic TCR signaling, respectively. Adoptive transfer studies suggest that relatively weak or strong Nur77-GFP intensity in thymocytes tends to be maintained in mature T cells. Two-dimensional affinity measurements were lowest for Nur77-GFP^loLy6C⁺ cells and highest for Nur77-GFP^hiLy6C^- cells, highlighting a positive correlation between apparent TCR affinity and tonic TCR signal strength. Despite experiencing the strongest tonic TCR signaling, Nur77-GFP^hiLy6C^- cells were least responsive to multiple concentrations of a cognate or suboptimal pMHC. Gene expression analyses suggest that Nur77-GFP^hiLy6C^- cells induce a gene expression program that has similarities with that of acutely stimulated T cells. However, strong tonic TCR signaling also correlates with increased expression of genes with inhibitory functions, including coinhibitory receptors. Similarly, assay for transposase-accessible chromatin with sequencing analyses suggested that increased tonic TCR signal strength correlated with increased chromatin accessibility associated with genes that have positive and inhibitory roles in T cell activation. Strikingly, Nur77-GFP^hiLy6C^- cells exhibited differential accessibility within regions of <i>Cd200r1</i> and <i>Tox</i> that were similar in location to differentially accessible regions previously identified in exhausted CD8⁺ T cells. We propose that constitutive strong tonic TCR signaling triggers adaptations detectable at both the transcriptional and epigenetic levels, ultimately contributing to the tuning of T cell responsiveness.ImmunoHorizonsStrong Basal/Tonic TCR Signals Are Associated with Negative Regulation of Naive CD4&lt;sup&gt;+&lt;/sup&gt; T Cells.PMC12917752K01 AG065485K01 AR065481Evavold BDScharer CDEggert JKolawole EMZinzow-Kramer WMAu-Yeung BBfalseStrong Basal/Tonic TCR Signals Are Associated with Negative Regulation of Naive CD4&lt;sup&gt;+&lt;/sup&gt; T Cells.T cells experience varying intensities of tonic or basal TCR signaling in response to self-peptides presented by MHC (self-pMHC) in vivo. We analyzed four subpopulations of mouse naive CD4⁺ cells that express different levels of Nur77-GFP and Ly6C, surrogate markers that positively and inversely correlate with the strength of tonic TCR signaling, respectively. Adoptive transfer studies suggest that relatively weak or strong Nur77-GFP intensity in thymocytes tends to be maintained in mature T cells. Two-dimensional affinity measurements were lowest for Nur77-GFP^loLy6C⁺ cells and highest for Nur77-GFP^hiLy6C^- cells, highlighting a positive correlation between apparent TCR affinity and tonic TCR signal strength. Despite experiencing the strongest tonic TCR signaling, Nur77-GFP^hiLy6C^- cells were least responsive to multiple concentrations of a cognate or suboptimal pMHC. Gene expression analyses suggest that Nur77-GFP^hiLy6C^- cells induce a gene expression program that has similarities with that of acutely stimulated T cells. However, strong tonic TCR signaling also correlates with increased expression of genes with inhibitory functions, including coinhibitory receptors. Similarly, assay for transposase-accessible chromatin with sequencing analyses suggested that increased tonic TCR signal strength correlated with increased chromatin accessibility associated with genes that have positive and inhibitory roles in T cell activation. Strikingly, Nur77-GFP^hiLy6C^- cells exhibited differential accessibility within regions of <i>Cd200r1</i> and <i>Tox</i> that were similar in location to differentially accessible regions previously identified in exhausted CD8⁺ T cells. We propose that constitutive strong tonic TCR signaling triggers adaptations detectable at both the transcriptional and epigenetic levels, ultimately contributing to the tuning of T cell responsiveness.2022-01-01T00:00:00Z2022 Sep2026-07-09T11:36:05.43Z2026-07-09T10:52:02.641ZS-EPMC129177523610036710.4049/immunohorizons.2200051