Project description:The cytotoxic activity of lymphocytes is particularly dependent on the regulated and polarised delivery of lytic granules to infected or malignant cells. Although genetic and mechanistic studies have identified a number of factors that regulate exocytosis in cytotoxic lymphocytes, a systematic mapping of the relevant factors and their relationships is lacking. Here, using a genome-scale CRISPR knockout screen in human natural killer cells, we characterise a complex genetic network regulating cytotoxic granule exocytosis, with lipid metabolism and protein lipidation among the most prominent pathways. By combining global protein lipidation and membrane lipid composition studies, we further uncover the critical role of ZDHHC17 in SNAP23 palmitoylation and targeting of palmitoylated SNAP23 to the membrane for cytotoxic granule fusion and release. Using ODYA-17 labelling of Ctrl and sgZDHHC17 NK-92 cells followed by pulldown and proteomic analysis, we investigated the palmitoylome of the NK-92 model cell line. By comparing the abundance of ODYA-17 labelled proteins in the lysates of Ctrl and sgZDHHC17 NK-92 cells, we defined the molecules that depend on the activity of the palmitoyl transferase ZDHHC17.
Project description:Regulated exocytosis controls key cellular functions ranging from neurotransmitter release to the secretion of immune mediators and its disruption is associated with numerous pathologies. The cytotoxic activity of lymphocytes is particularly dependent on regulated and polarized lytic granule delivery towards infected or malignant cells. Although genetic and mechanistic studies have identified factors regulating exocytosis in cytotoxic lymphocytes, a systematic mapping of the relevant factors and their relationships is lacking. Through a genome-scale CRISPR knockout screen in a human natural killer cell line, we characterized a complex genetic network regulating cytotoxic granule exocytosis, with lipid metabolism and protein lipidation amongst the most prominent pathways. By combining global protein lipidation and membrane lipid composition studies, we found that ZDHHC17 drives palmitoylation of the core SNARE complex protein SNAP23 to target cytotoxic granules to GM1-rich lipid rafts whose assembly is controlled by serine palmitoyltransferase.
Project description:Cdc42 is a Rho family GTPase known for its central role in cell polarity and cytoskeletal regulation. To understand the role of Cdc42 in polarised secretion from cytotoxic T lymphocytes (CTLs) we used CRISPR/Cas9 gene deletion. While Cdc42-deleted CTLs initially showed reduced secretion for up to two days after CRISPR-mediated deletion, full secretion was rapidly restored and even enhanced while CDC42 protein remained absent. In contrast, chemical inhibition of CDC42 using CASIN consistently decreased secretion in wild-type cells, but had no impact on Cdc42-deleted CTLs, confirming the specificity of this inhibitor. Comparative proteomics and transcriptomics of CTLs after Cdc42-deletion revealed transcriptional changes that could support improved T cell function including compensation via other Rho GTPases. Targeting the promoter region of Cdc42 did not trigger transcriptional adaptation, consistent with a nonsense-mediated decay mechanism of genetic compensation. Our work highlights the importance of taking orthogonal approaches to study protein function, and reveals the remarkable robustness of primary T cells to adapt to loss of an essential gene.
Project description:Treg cells play an important role in immune tolerance and tumor immune evasion through suppression of effector T cells. Treg cell lineage instability may be harnessed to trigger anti-tumor T cell immunity. However, the mechanism underlying Treg cell stability remains poorly understand. By characterizing Treg cell-specific heterozygous and homozygous Cdc42 knockout mice, we found that Cdc42 is essential for Treg cell stability. By RNA sequencing of heterozygous and homozygous Cdc42 knockout Treg cells, we found that Cdc42 maintains Treg cell stability through suppression of carbonic anhydrase I (CAI) expression.
Project description:Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death. However, the mechanism for HCC initiation remains poorly known. Cdc42, a small Rho GTPase, with multiple cellular functions has been shown involved in variant types of human cancers, but its role in HCC initiation remains unclear. Cdc42 liver-specific knockout mice (Cdc42LK) developed HCC at 6-month-old. We used microarrays to detail the global programme of gene expression induced by Cdc42 deletion and identified distinct classes of up or down-regulated genes during HCC initial time.
Project description:We wished to examine early transcriptional changes that occur after TCR engagement in CD8+ cytotoxic T lymphocytes (CTLs). To this end, we differentiated effector CTLs from OTI TCR transgenic mice for 7 days in vitro and then stimulated them with anti-CD3 for various times before lysing for RNA-seq. Results demonstrated significant transcriptional changes starting from 20 minutes. After 60 minutes, upregulated genes were most enriched for cytokines and transcriptional machinery.
Project description:We investigated transcriptional changes in MAZR-, Runx3- and MAZR/Runx3-deficient cytotoxic T lymphocytes (CTLs). This analysis revealed that MAZR plays a compensatory role in the Runx3-dependent transcriptional program of CTL differentiation.
Project description:Neoantigen-reactive cytotoxic T lymphocytes play a vital role in precise cancer cell elimination. In this study, we demonstrate the effectiveness of personalized neoantigen-based T cell therapy in inducing tumor regression in two patients suffering from heavily-burdened metastatic ovarian cancer. Our approach involved the development of a robust pipeline for ex vivo expansion of neoantigen-reactive T lymphocytes. Neoantigen peptides were designed and synthesized based on the somatic mutations of the tumors and their predicted HLA binding affinities. These peptides were then presented to T lymphocytes through co-culture with neoantigen-loaded dendritic cells for ex vivo expansion. Subsequent to cell therapy, both patients exhibited significant reductions in tumor marker levels and experienced substantial tumor regression. One patient achieved repeated cancer regression through infusions of T cell products generated from newly identified neoantigens. Transcriptomic analyses revealed a remarkable increase in neoantigen-reactive cytotoxic lymphocytes in the peripheral blood of the patients following cell therapy. These cytotoxic T lymphocytes expressed polyclonal T cell receptors (TCR) against neoantigens, along with abundant cytotoxic proteins and pro-inflammatory cytokines. The efficacy of neoantigen targeting was significantly associated with the immunogenicity and TCR polyclonality. Notably, the neoantigen-specific TCR clonotypes persisted in the peripheral blood after cell therapy. Our findings indicate that personalized neoantigen-based T cell therapy triggers cytotoxic lymphocytes expressing polyclonal TCR against ovarian cancer, suggesting its promising potential in cancer immunotherapy.