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Published on: November 30, 2013
METTL3-Mediated N 6 -Methyladenosine mRNA Modification and cGAS-STING Pathway Activity in Kidney Fibrosis
Yu-Cheng Tsai1,2, Tsung-Han Hsieh3, Yuan-Ru Liao1,2
1Division of Nephrology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
Background:
Chemical modifications on RNA profoundly affect RNA function and regulation. m6A, the most abundant RNA modification in eukaryotes, plays a pivotal role in diverse cellular processes and disease mechanisms. However, its importance is understudied in human CKD samples regarding its influence on pathological mechanisms.
Methods:
Liquid chromatography–tandem mass spectrometry and methylated RNA immunoprecipitation sequencing were used to examine alterations in m6A levels and patterns in CKD samples. Overexpression of the m6A writer METTL3 in cultured kidney tubular cells was performed to confirm the effect of m6A in tubular cells and explore the biological functions of m6A modification on target genes. In addition, tubule-specific deletion of Mettl3 (Ksp-Cre Mettl3f/f) mice and antisense oligonucleotides inhibiting Mettl3 expression were used to reduce m6A modification in an animal kidney disease model.
Results:
By examining 127 human CKD samples, we observed a significant increase in m6A modification and METTL3 expression in diseased kidneys. Epitranscriptomic analysis unveiled an enrichment of m6A modifications in transcripts associated with the activation of inflammatory signaling pathways, particularly the cyclic guanosine monophosphate–AMP synthase (cGAS)-stimulator of IFN genes (STING) pathway. m6A hypermethylation increased mRNA stability in cGAS and STING1 as well as elevated the expression of key proteins within the cGAS-STING pathway. Both the tubule-specific deletion of Mettl3 and the use of antisense oligonucleotides to inhibit Mettl3 expression protected mice from inflammation, reduced cytokine expression, decreased immune cell recruitment, and attenuated kidney fibrosis.
Conclusions:
Our research revealed heightened METTL3-mediated m6A modification in fibrotic kidneys, particularly enriching the cGAS-STING pathway. This hypermethylation increased mRNA stability for cGAS and STING1, leading to sterile inflammation and fibrosis.
Insights
Increased N6-methyladenosine (m6A) RNA modification and METTL3 expression in chronic kidney disease (CKD) kidneys activate inflammatory pathways, driving fibrosis. Reducing m6A levels protects against kidney disease progression.
Area of Science:
- Biochemistry
- Molecular Biology
- Pathology
Background:
- N6-methyladenosine (m6A) is the most abundant RNA modification in eukaryotes, crucial for RNA function and regulation.
- While m6A's role in cellular processes and disease is recognized, its specific impact on pathological mechanisms in human chronic kidney disease (CKD) remains understudied.
- This study investigates the role of m6A modification in the progression of kidney disease.
Purpose of the Study:
- To investigate the alterations in m6A levels and patterns in human CKD samples.
- To elucidate the functional role of m6A modification, particularly mediated by METTL3, in kidney tubular cells and CKD pathogenesis.
- To explore the therapeutic potential of targeting m6A modification in kidney disease.
Main Methods:
- Liquid chromatography–tandem mass spectrometry and methylated RNA immunoprecipitation sequencing were employed to analyze m6A alterations in CKD samples.
- METTL3 was overexpressed in kidney tubular cells to study m6A's effects, and its expression was manipulated in vivo using tubule-specific deletion (Ksp-Cre Mettl3f/f mice) and antisense oligonucleotides.
- Epitranscriptomic analysis identified m6A-modified transcripts and associated signaling pathways.
Main Results:
- A significant increase in m6A modification and METTL3 expression was observed in 127 human CKD samples.
- m6A hypermethylation was enriched in transcripts of the cyclic guanosine monophosphate–AMP synthase (cGAS)-stimulator of IFN genes (STING) pathway, increasing mRNA stability of cGAS and STING1.
- Inhibition of METTL3 in mice attenuated kidney inflammation, reduced cytokine expression, decreased immune cell infiltration, and mitigated kidney fibrosis.
Conclusions:
- Heightened METTL3-mediated m6A modification is a key feature of fibrotic kidneys, specifically promoting the cGAS-STING pathway.
- This m6A hypermethylation enhances cGAS and STING1 mRNA stability, contributing to sterile inflammation and kidney fibrosis.
- Targeting METTL3-mediated m6A modification presents a potential therapeutic strategy for mitigating kidney fibrosis and inflammation.
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