CPT1A induction following epigenetic perturbation promotes MAVS palmitoylation and activation to potentiate antitumor immunity
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ABSTRACT: Targeting epigenetic regulators to potentiate anti-PD-1 immunotherapy converges on the activation of type I interferon (IFN-I) response, mimicking cellular response to viral infection, but how its strength and duration are regulated to impact combination therapy efficacy remains largely unknown. Here, we show that mitochondrial CPT1A downregulation following viral infection restrains, while its induction by epigenetic perturbations sustains, a double-stranded RNA-activated IFN-I response. Mechanistically, CPT1A recruits the endoplasmic reticulum-localized ZDHHC4 to catalyze MAVS Cys79-palmitoylation, which promotes MAVS stabilization and activation by inhibiting K48- but facilitating K63-linked ubiquitination. Further elevation of CPT1A incrementally increases MAVS palmitoylation and amplifies the IFN-I response, which enhances control of viral infection and epigenetic perturbation-induced antitumor immunity. Moreover, CPT1A chemical inducers augment the therapeutic effect of combined epigenetic treatment with PD-1 blockade in refractory tumors. Our study identifies CPT1A as a stabilizer of MAVS activation, and its link to epigenetic perturbation can be exploited for cancer immunotherapy.
Project description:argeting epigenetic regulators to potentiate anti-PD-1 immunotherapy converges on the activation of type I interferon (IFN-I) response, mimicking cellular response to viral infection, but how its strength and duration are regulated to impact combination therapy efficacy remains largely unknown. Here, we show that mitochondrial CPT1A downregulation following viral infection restrains, while its induction by epigenetic perturbations sustains, a double-stranded RNA-activated IFN-I response. Mechanistically, CPT1A recruits the endoplasmic reticulum-localized ZDHHC4 to catalyze MAVS Cys79-palmitoylation, which promotes MAVS stabilization and activation by inhibiting K48- but facilitating K63-linked ubiquitination. Further elevation of CPT1A incrementally increases MAVS palmitoylation and amplifies the IFN-I response, which enhances control of viral infection and epigenetic perturbation-induced antitumor immunity. Moreover, CPT1A chemical inducers augment the therapeutic effect of combined epigenetic treatment with PD-1 blockade in refractory tumors. Our study identifies CPT1A as a stabilizer of MAVS activation, and its link to epigenetic perturbation can be exploited for cancer immunotherapy.
Project description:Innate immunity serves as the primary defense against viral and microbial infections in humans. Among its components, retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) are well-characterized intracellular pattern-recognition proteins that trigger innate immune responses upon viral infection. However, the precise influence of cellular metabolites, especially fatty acids, on the regulation of RLR-mediated antiviral innate immunity remains largely elusive. Here, through screening a metabolite library, palmitic acid (PA) has been identified as a crucial metabolite responsible for modulating antiviral infections. Mechanistically, PA induces the palmitoylation of MAVS, leading to MAVS aggregation and subsequent activation, thereby enhancing the innate immune response against viral infections. Functionally, the enzyme palmitoyl-transferase ZDHHC24 plays a key role in catalyzing the palmitoylation of MAVS at both C46 and C79 residues, thereby facilitating the transduction of RLR-mediated TBK1-IRF3-IFN signaling pathway, particularly under conditions of PA stimulation or high-fat diet feeding. Conversely, the absence of ZDHHC24 significantly attenuates virus-induced innate immune responses in both cells and mice. Moreover, APT2 counteracts with ZDHHC24 to de-palmitoylate MAVS, thus inhibiting the antiviral response. Consequently, inhibition of APT2 using compounds like ML349 effectively reverses MAVS palmitoylation and activation in response to antiviral infections. These findings underscore the critical role of PA and ZDHHC24 in regulating antiviral innate immunity through MAVS palmitoylation, and suggest potential therapeutic strategies for combating viral infections, such as enhancing PA intake or specifically targeting APT2.
Project description:Pattern recognition receptors (PRRs)-mediated innate immune responses are critical for host defense against microbial pathogens including RNA/DNA viruses. A growing number of coding genes and genes originally defined as non-coding RNAs (ncRNAs) are found to encode short peptides or proteins, named microproteins. However, the landscape of microproteins in responsive to virus infection and the functions of these microproteins remain uncharacterized. Here, we systematically identified microproteins, both from coding and non-coding genes, that are responsive to Vesicular Stomatitis Virus (VSV) infection. Among which, a highly conserved, endoplasmic reticulum (ER) membrane-localized microprotein, , MAVI1 (microprotein in antiviral immunity 1), was found to interact with mitochondrial localized MAVS protein, inhibiting the aggregation of MAVS and the activation of downstream type I interferon (IFN) signaling pathway. The critical role of MAVI1 was highlighted that viral infection was significantly attenuated and survival rate was significantly increased in Mavi1 knockout mice in vivo. A peptide inhibitor targeting the interaction between MAVI1 and MAVS is potent in activating the type I IFN signaling and defending viral infection both in vitro and in vivo. Our findings uncovered that microproteins could play critical roles in regulating antiviral innate immune responses via cross-organelle interaction, and targeting microproteins might represent a potential therapeutic avenue for treating viral infection in clinic.
Project description:Despite the remarkable achievement of immune checkpoint blockade (ICB) therapy, the response rate is relatively low and only a subset of patients can benefit from the treatment. We hypothesize that targeting RNA decay machinery may lead to accumulation of aberrantRNA, triggering interferon (IFN) signaling and sensitizing tumor cells to immunotherapy. With this in mind, we identified an RNA exoribonuclease, XRN1 as a potential target. Silencing of XRN1 suppressed tumor growth in syngeneic immunocompetent mice and potentiated immunotherapy, while silencing of XRN1 alone did not affect tumor growth in immune deficient mice. Mechanistically, XRN1 depletion activated interferon signaling and viral defense pathway; both pathways play determinant roles in regulating immune evasion. We identified aberrant-RNA sensing signaling proteins (RIG-I/MAVS and PKR) in mediating the expression of IFN genes, as depletion of each of them blunted the elevation of anti-viral/IFN signaling in Xrn1 silenced cells. Analysis of pan-cancer CRISPR screening data indicated that IFN signaling triggered by Xrn1 silencing is a common phenomenon, suggesting that the effect of Xrn1 silencing may be extend to multiple types of cancers.
Project description:While inhibition of T cell co-inhibitory receptors has revolutionized cancer therapy, the mechanisms governing their expression on human T cells have not been elucidated. Type 1 interferon (IFN-I) modulates T cell immunity in viral infection, autoimmunity, and cancer, and may facilitate induction of T cell exhaustion in chronic viral infection. Here we show that IFN-I regulates co-inhibitory receptor expression on human T cells, inducing PD-1/TIM-3/LAG-3 while surprisingly inhibiting TIGIT expression. High-temporal-resolution mRNA profiling of IFN-I responses enabled the construction of dynamic transcriptional regulatory networks uncovering three temporal transcriptional waves. Perturbation of key transcription factors on human primary T cells revealed unique regulators that control expression of co-inhibitory receptors. We found that the dynamic IFN-I response in vitro closely mirrored T cell features with IFN-I linked acute SARS-CoV-2 infection in human, with high LAG3 and decreased TIGIT expression. Finally, our gene regulatory network identified SP140 as a key regulator for differential LAG3 and TIGIT expression, which were validated at the level of protein expression. The construction of IFN-I regulatory networks with identification of unique transcription factors controlling co-inhibitory receptor expression may provide targets for enhancement of immunotherapy in cancer, infectious diseases, and autoimmunity.
Project description:While inhibition of T cell co-inhibitory receptors has revolutionized cancer therapy, the mechanisms governing their expression on human T cells have not been elucidated. Type 1 interferon (IFN-I) modulates T cell immunity in viral infection, autoimmunity, and cancer, and may facilitate induction of T cell exhaustion in chronic viral infection. Here we show that IFN-I regulates co-inhibitory receptor expression on human T cells, inducing PD-1/TIM-3/LAG-3 while surprisingly inhibiting TIGIT expression. High-temporal-resolution mRNA profiling of IFN-I responses enabled the construction of dynamic transcriptional regulatory networks uncovering three temporal transcriptional waves. Perturbation of key transcription factors on human primary T cells revealed unique regulators that control expression of co-inhibitory receptors. We found that the dynamic IFN-I response in vitro closely mirrored T cell features with IFN-I linked acute SARS-CoV-2 infection in human, with high LAG3 and decreased TIGIT expression. Finally, our gene regulatory network identified SP140 as a key regulator for differential LAG3 and TIGIT expression, which were validated at the level of protein expression. The construction of IFN-I regulatory networks with identification of unique transcription factors controlling co-inhibitory receptor expression may provide targets for enhancement of immunotherapy in cancer, infectious diseases, and autoimmunity.
Project description:While inhibition of T cell co-inhibitory receptors has revolutionized cancer therapy, the mechanisms governing their expression on human T cells have not been elucidated. Type 1 interferon (IFN-I) modulates T cell immunity in viral infection, autoimmunity, and cancer, and may facilitate induction of T cell exhaustion in chronic viral infection. Here we show that IFN-I regulates co-inhibitory receptor expression on human T cells, inducing PD-1/TIM-3/LAG-3 while surprisingly inhibiting TIGIT expression. High-temporal-resolution mRNA profiling of IFN-I responses enabled the construction of dynamic transcriptional regulatory networks uncovering three temporal transcriptional waves. Perturbation of key transcription factors on human primary T cells revealed unique regulators that control expression of co-inhibitory receptors. We found that the dynamic IFN-I response in vitro closely mirrored T cell features with IFN-I linked acute SARS-CoV-2 infection in human, with high LAG3 and decreased TIGIT expression. Finally, our gene regulatory network identified SP140 as a key regulator for differential LAG3 and TIGIT expression, which were validated at the level of protein expression. The construction of IFN-I regulatory networks with identification of unique transcription factors controlling co-inhibitory receptor expression may provide targets for enhancement of immunotherapy in cancer, infectious diseases, and autoimmunity.