CPT1A induction following epigenetic perturbation promotes MAVS palmitoylation and activation to potentiate antitumor immunity

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. Overall design: GFP-labeled scramble, LSD1 KO and LSD1/CPT1A DKO B16/F10 tumors were implanted in C57BL/6 mice for 14 days. Tumors were harvested, dissociated into single cells, and subjected to GFP+ tumor cell isolation by FACS. Total RNA was extracted and used to poly(A)+ RNA enrichment by magnetic mRNA isolation kit for constructing library. The prepared libraries were sequenced at 150 bp from both ends.