scRNA-seq reveals ATPIF1 activity in control of T cell antitumor activity

ATP synthase inhibitory factor 1 (ATPIF1) is a mitochondrial protein with an activity in inhibition of F₁F_o-ATP synthase. ATPIF1 activity remains unknown in the control of immune activity of T cells. In this study, we identified ATPIF1 activity in the induction of CD8⁺ T cell function in tumor models through genetic approaches. ATPIF1 gene inactivation impaired the immune activities of CD8⁺ T cells leading to quick tumor growth (B16 melanoma and Lewis lung cancer) in ATPIF1-KO mice. The KO T cells exhibited a reduced activity in proliferation and IFN-γ secretion with metabolic reprogramming of increased glycolysis and decreased oxidative phosphorylation (OXPHOS) after activation. T cell exhaustion was increased in the tumor infiltrating leukocytes (TILs) of KO mice as revealed by the single-cell RNA sequencing (scRNA-seq) and confirmed by flow cytometry. In contrast, ATPIF1 overexpression in T cells increased expression of IFN-γ and Granzyme B, subset of central memory T cells in CAR-T cells, and survival rate of NALM-6 tumor-bearing mice. These data demonstrate that ATPIF1 deficiency led to tumor immune deficiency through induction of T cell exhaustion. ATPIF1 overexpression enhanced the T cell tumor immunity. Therefore, ATPIF1 is a potential molecular target in the modulation of antitumor immunity of CD8⁺ T cells in cancer immunotherapy. Induction of ATPIF1 activity may promote CAR-T activity in cancer therapy.