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Methodology for Accurate Detection of Mitochondrial DNA Methylation
Published on: May 20, 2018
Mitochondrial DNA 6 mA methylation by METTL4 drives neuroinflammation via cGAS-STING activation in vascular cognitive
Zhe Gong1, Ziyi Chen2, Shuixian Sang2
1Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
Background:
Vascular cognitive impairment (VCI) is strongly associated with mitochondrial dysfunction, yet the underlying molecular mechanisms connecting mitochondrial impairment to neuroinflammation remain elusive. While mitochondrial epigenetic modifications are emerging as key regulators of cellular metabolism, the role of mitochondrial DNA (mtDNA) N6-methyladenine (6 mA) modification and its writer enzyme METTL4 in VCI pathogenesis has not been established.
Methods:
Using complementary in vitro (oxygen-glucose deprivation, OGD) and in vivo (chronic cerebral hypoperfusion, CCH) models of VCI, we systematically investigated METTL4-mediated mtDNA epigenetic regulation. Approaches included RNA sequencing (RNA-seq), mitochondrial functional assays, reactive oxygen species (ROS) measurement, and comprehensive analysis of cGAS-STING-mediated neuroinflammatory responses.
Results:
We identified mitochondrial-specific enrichment of METTL4 in hippocampal neurons, with significantly elevated mtDNA 6 mA levels following CCH. Mechanistically, OGD-induced METTL4 preferentially methylated the light-strand promoter region of mtDNA, leading to (Dichgans and Leys, 2017) [1]: impaired electron transport chain (ETC) activity (Kim et al., 2020) [2], excessive ROS production, and (Johnson, 2023) [3] oxidized mtDNA leakage. These mitochondrial abnormalities robustly activated the cGAS-STING neuroinflammatory pathway. Genetic inhibition of METTL4 normalized 6 mA levels, restored mitochondrial gene expression profiles, and significantly improved cognitive function in VCI models.
Conclusion:
Our study delineates a complete METTL4-mtDNA 6 mA-mitochondrial dysfunction-neuroinflammation axis in VCI pathogenesis. These findings not only provide novel insights into the epigenetic control of neuroinflammation but also position METTL4 as a promising therapeutic target for mitigating cerebrovascular-related cognitive decline.
Insights
This study reveals how METTL4-mediated mitochondrial DNA (mtDNA) epigenetic changes drive neuroinflammation in vascular cognitive impairment (VCI). Inhibiting METTL4 improves mitochondrial function and cognitive deficits in VCI models.
Area of Science:
- Neuroscience
- Epigenetics
- Mitochondrial Biology
Background:
- Vascular cognitive impairment (VCI) is linked to mitochondrial dysfunction, but the mechanisms causing neuroinflammation are unclear.
- The role of mitochondrial DNA (mtDNA) N6-methyladenine (6mA) modification and its writer enzyme METTL4 in VCI is unknown.
Purpose of the Study:
- To investigate METTL4-mediated mtDNA epigenetic regulation in VCI.
- To explore the connection between METTL4, mitochondrial dysfunction, and neuroinflammation in VCI.
Main Methods:
- Utilized in vitro (oxygen-glucose deprivation) and in vivo (chronic cerebral hypoperfusion) VCI models.
- Employed RNA sequencing, mitochondrial function assays, ROS measurement, and cGAS-STING pathway analysis.
Main Results:
- METTL4 and mtDNA 6mA levels were elevated in VCI models, particularly in hippocampal neurons.
- METTL4-induced mtDNA methylation impaired electron transport chain activity, increased ROS, and led to mtDNA leakage, activating the cGAS-STING pathway.
- Inhibiting METTL4 restored mitochondrial function, normalized gene expression, and improved cognitive function.
Conclusions:
- A METTL4-mtDNA 6mA-mitochondrial dysfunction-neuroinflammation axis was identified in VCI pathogenesis.
- METTL4 is a potential therapeutic target for VCI and related cognitive decline.
