METTL3-Mediated N 6 -Methyladenosine mRNA Modification and cGAS-STING Pathway Activity in Kidney Fibrosis

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.