| abstract |
The innate immune response serves as the primary defense against microbial infection,
triggered by the detection of Pathogen-Associated Molecular Patterns (PAMPs) by Pattern
Recognition Receptors (PRRs). During viral infection, activation of the cGAS-STING pathway
triggers a signaling cascade resulting in the production of Type I Interferons (IFNs) and the
subsequent expression of Interferon-Stimulated Genes (ISGs) to establish an antiviral state.
Although the recognition of RNA and DNA were long considered to occur via distinct pathways,
recent investigations reveal that RNA virus infections can unexpectedly activate DNA-sensing
proteins. This activation is driven by cellular stress and the leakage of mitochondrial DNA
(mtDNA) into the cytosol, where it acts as a Damage-Associated Molecular Pattern (DAMP).
Given that RNA viruses trigger mtDNA leakage after viral genome recognition, we hypothesize
that DNA viruses employ a parallel mechanism where mtDNA is partially responsible for
cGAS-STING activation.
To investigate this, we utilized a THP-1 cell model treated with ABT-737 and
Q-VD-OPH to induce mtDNA release and prevent cell death. Using an adapted DNA
fractionation protocol and reverse transcription quantitative real-time PCR (RT-qPCR), we
confirmed that ABT-737 and Q-VD-OPH successfully trigger the transcriptional upregulation of
ISGs and IFNs. Our initial results demonstrate that while total cellular DNA levels remain
constant across all conditions, mtDNA leaks into the cytosol following viral DNA stimulation,
lipid transfection, and the pharmacological treatment. This model provides a robust framework to
decouple the sensing of exogenous viral DNA from endogenous mtDNA leakage, clarifying the
specific contributions of each to the cGAS-STING response during DNA virus infection.
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