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Kim, H.-D.

Publications and source records attributed to Kim, H.-D..

2 recordsLinked to original sources

Transcriptional Profiling of D1-MSNs Reveals SIRT1-Dependent and -Independent Responses to Chronic Social Defeat Stress

SIRT1 is a critical regulator of neuronal functions and has been implicated in various neurological disorders, including depression. In a previous study, we demonstrated the pro-depressive roles of SIRT1 in the nucleus accumbens (NAc) using the chronic social defeat stress (CSDS) model, a well-validated preclinical mouse model of depression. We found that SIRT1 modulates synaptic functions and exhibits pro-susceptible effects specifically in D1-medium spiny neurons in the NAc. In this study, we extended our investigation of SIRT1 functions by employing cell-type-specific transcriptomics to compare control and susceptible groups under CSDS. Our results revealed that in wild-type mice with functional SIRT1, cellular metabolism is crucial for inducing susceptibility to depression. Conversely, in the absence of functional SIRT1 expression, circadian clock-controlled transcriptional regulation becomes a key factor. These findings suggest that SIRT1 differentially modulates key pathophysiological mechanisms of depression via its deacetylase functions, highlighting its role in both metabolic and circadian regulation in the brain. This research provides new insights into the molecular underpinnings of depression and identifies potential targets for therapeutic intervention.

neuroscience↗

TCR signaling via NFATc1 constrains IL-15-induced NK-like activation of human memory CD8+ T cells

Here we investigated the regulatory mechanisms of TCR-independent bystander activation and NK-like cytotoxicity of human memory CD8+ T cells. We found that TCR signals suppressed characteristic features of IL-15-induced CD8+ T-cell activation, including increased NKG2D expression and upregulation of genes related to NK cytotoxicity and IFN response. Moreover, ionomycin suppressed IL-15-induced bystander activation and NK-like cytotoxicity, indicating that Ca2+-calcineurin signaling is responsible for TCR-mediated suppression of IL-15-induced bystander activation. In detail, NFATc1 suppressed IL-15-induced bystander activation via binding to AP-1 that is necessary for the IL-15-induced upregulation of NK cytotoxicity-related genes. Consistent with these results, calcineurin inhibitors enhanced IL-15-induced NKG2D expression in the presence of TCR signals. Additionally, we defined genes upregulated by IL-15 and downregulated by concurrent TCR signals as an IL-15-induced bystander activation gene set, and found that this gene signature was upregulated in bystander CD8+ T cells from patients with hepatitis A virus infection. This study paves the way for further investigation of bystander CD8+ T-cell activation in various pathological conditions, and its regulation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=191 HEIGHT=200 SRC="FIGDIR/small/632884v2_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@1e6c320org.highwire.dtl.DTLVardef@114a23eorg.highwire.dtl.DTLVardef@1a7b9edorg.highwire.dtl.DTLVardef@9faccc_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LITCR signaling downregulates IL-15-induced transcriptomic features related to NK-like bystander activation of human memory CD8+ T cells via the Ca2+-calcineurin pathway. C_LIO_LINFATc1 suppresses IL-15-induced bystander activation via binding to AP-1, which is responsible for IL-15-induced NK-like cytotoxic activity. C_LIO_LICalcineurin inhibitors cannot suppress IL-15-induced bystander CD8+ T-cell activation, and paradoxically increase IL-15-induced NKG2D expression in the presence of TCR signals. C_LIO_LIGenes upregulated by IL-15 and downregulated by concurrent TCR signals define the gene set of bystander CD8+ T-cell activation, which was validated in disease contexts. C_LI

immunology↗