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Updated: Sep 21, 2025
Intravitreous Injection for Establishing Ocular Diseases Model
Published on: October 1, 2007
Intravitreal injection of mitochondrial DNA induces cell damage and retinal dysfunction in rats
Yue Guo1, Dekang Gan1,2,3, Fangyuan Hu4
1Department of Ophthalmology, Eye and ENT Hospital of Fudan University, Shanghai, 200031, China.
Background:
Retinal neurodegeneration is induced by a variety of environmental insults and stresses, but the exact mechanisms are unclear. In the present study, we explored the involvement of cytosolic mitochondrial DNA (mtDNA), resulting in the cGAS-STING dependent inflammatory response and apoptosis in retinal damage in vivo.
Methods:
Retinal injury was induced with white light or intravitreal injection of lipopolysaccharide (LPS). After light- or LPS-induced injury, the amount of cytosolic mtDNA in the retina was detected by PCR. The mtDNA was isolated and used to transfect retinas in vivo. WB and real-time PCR were used to evaluate the activation of cGAS-STING pathway and the levels of apoptosis-associated protein at different times after mtDNA injection. Retinal cell apoptosis rate was detected by TUNEL staining. Full-field electroretinography (ERG) was used to assess the retinal function.
Results:
Light injury and the intravitreal injection of LPS both caused the leakage of mtDNA into the cytoplasm in retinal tissue. After the transfection of mtDNA in vivo, the levels of cGAS, STING, and IFN-β mRNAs and the protein levels of STING, phosph-TBK1, phospho-IRF3, and IFN-β were upregulated. mtDNA injection also induced the activation of caspase 3 and caspase 9. BAX and BAK were increased at both the mRNA and protein levels. The release of cytochrome c from the mitochondria to the cytosol was increased after mtDNA injection. The wave amplitudes on ERG decreased and retinal cell apoptosis was detected after mtDNA injection.
Conclusions:
Cytosolic mtDNA triggers an inflammatory response. It also promotes apoptosis and the dysfunction of the retina.
Insights
Cytosolic mitochondrial DNA (mtDNA) triggers inflammation and apoptosis, leading to retinal damage. This study reveals mtDNA
Area of Science:
- Ophthalmology
- Immunology
- Cell Biology
Background:
- Retinal neurodegeneration mechanisms remain unclear.
- Environmental factors can induce retinal damage.
- Cytosolic mitochondrial DNA (mtDNA) involvement is explored.
Purpose of the Study:
- Investigate cytosolic mtDNA's role in retinal damage.
- Elucidate the cGAS-STING inflammatory pathway in retinal injury.
- Determine mtDNA-induced apoptosis in retinal cells.
Main Methods:
- Retinal injury induced by light or LPS.
- Cytosolic mtDNA quantified using PCR.
- mtDNA transfection in vivo, followed by pathway analysis (WB, real-time PCR).
- Apoptosis assessed by TUNEL staining and caspase activity.
- Retinal function evaluated by electroretinography (ERG).
Main Results:
- Light and LPS induced mtDNA leakage into the cytoplasm.
- mtDNA transfection upregulated cGAS-STING pathway components (cGAS, STING, IFN-β).
- mtDNA injection activated caspases (3, 9) and apoptotic proteins (BAX, BAK).
- Mitochondrial cytochrome c release increased, ERG amplitudes decreased, and apoptosis was observed.
Conclusions:
- Cytosolic mtDNA acts as a trigger for retinal inflammation.
- mtDNA promotes retinal cell apoptosis and dysfunction.
- The cGAS-STING pathway mediates mtDNA-induced retinal damage.
