Cooperative sensing of mitochondrial DNA by ZBP1 and cGAS promotes cardiotoxicity

Abstract

Mitochondrial DNA (mtDNA) is a potent agonist of the cyclic GMP-AMP (cGAMP) synthase (cGAS)-Stimulator of Interferon Genes (STING)-type I interferon (IFN-I) pathway. However, the kinetics of mtDNA detection by cGAS or other nucleic acid sensors and the exact immunostimulatory features of mtDNA remain poorly defined. Here, we show that robust and sustained IFN-I responses downstream of mtDNA stress require the nucleic acid sensor Z-DNA binding protein 1 (ZBP1) in a cell death independent manner. Cells experiencing persistent mtDNA release display robust ZBP1 expression, as well as a marked increase in the cytoplasmic pool of cGAS. Biochemical and microscopy analyses reveal that the receptor-interacting protein homotypic interaction motif (RHIMs) of ZBP1 bind the N-terminus of cGAS, leading to its entrapment in the cytoplasm. Moreover, we show that genetic and pharmacologic induction of mtDNA stress leads to the mitochondrial and cytoplasmic accumulation of Z-form DNA. Nuclease treatment or deletion of Z-DNA binding domains of ZBP1 reduces its interaction with cGAS and impairs cGAMP production downstream of mtDNA stress. Finally, we uncover that ZBP1 is a novel regulator of IFN-I-mediated disease pathology, working in tandem with the cGAS-STING pathway to sense mtDNA instability and sustain IFN-I signaling that contributes to cardiac remodeling and heart failure. These results provide new insight into the molecular mechanisms of mtDNA sensing by the innate immune system and reveal that ZBP1 is a cooperative partner for cGAS. Moreover, our findings highlight ZBP1 as a potential therapeutic target in heart failure and other disorders where mtDNA instability drives disease-promoting IFN-I and inflammatory responses.

Identification of a Multi-Messenger RNA Signature as Type 2 Diabetes Mellitus Candidate Genes Involved in Crosstalk between Inflammation and Insulin Resistance

“…A previous study by Jiao et al, in 2020, suggested that activation of ZBP1 may lead to necrosis and chronic inflammation through triggering receptor-interacting serine/threonine-protein kinase 3 (RIPK3) [ 39 ]. A study made by Lei, Y. et al, in 2022, stated that ZBP1 can be considered a new regulator of IFN-1-mediated disease progression, acting on the cGAS-STING pathway to sense mitochondrial DNA (mtDNA) instability and sustain IFN-1 signaling, which has a role in heart failure and cardiac cell remodeling [ 15 ]. Previous studies found that single-point mutations in genes responsible for innate immunity as DDX58 might have a role in the risk of developing T1DM [ 40 ].…”

“…STING knockout significantly improved insulin resistance and glucose intolerance in rat on a high-fat diet [ 8 ]. Z-DNA-binding protein 1 (ZBP1) is a positive mediator of innate immunity through its cooperation with the cGAS-STING pathway [ 15 ]. ZBP1 is a cytoplasmic sensor of DNA and has an important role in the immune response activated by the introduction of different viruses inside the body [ 16 ].…”