FTO-mediated mA demethylation of CRTC1 coordinates with p300 and EGR2 to promote alveolar ECM degradation in acute respiratory distress syndrome.

Abstract

BACKGROUND: N6-methyladenosine (mA) RNA modification is key epigenetic mechanism implicated in various diseases, yet its role in acute respiratory distress syndrome (ARDS) remains unclear. METHODS: An ARDS mouse model was generated via intratracheal administration of lipopolysaccharide (LPS). Transcriptomic profiling by RNA sequencing identified differentially expressed genes. Protein-protein interactions were assessed through immunoprecipitation and co-immunoprecipitation assays. Gene and protein expression levels were measured by reverse transcription-quantitative PCR and Western blotting. Histopathological analysis assessed tissue injury. RESULTS: We observed a marked upregulation of the mA demethylase FTO (Fat mass and obesity-associated protein) in LPS-challenged alveolar macrophages (AMs). FTO coordinates with the mA reader YTHDF2 (YT521-B homology domain family member 2) to modulate the mRNA stability and expression of the transcriptional coactivator CRTC1 (CREB-regulated transcription coactivator 1). Elevated CRTC1 protein assembled a transcriptional complex with the histone acetyltransferase p300 and the transcription factor EGR2 (Early growth response protein 2). This complex transcriptionally activates a subset of extracellular matrix (ECM)-degrading enzymes, including MMP8/14/17/23 (Matrix metalloproteinases 8/14/17/23) and ADAMTS3/5/7/15 (A disintegrin and metalloproteinase with thrombospondin motifs 3/5/7/15). These proteases degrade the alveolar basement membrane, increasing alveolar-capillary permeability and promoting inflammation-key features of ARDS. FTO inhibition or knockdown suppressed MMP and ADAMTS expression, alleviating ECM degradation and preventing ARDS onset in mice. CONCLUSION: These results define a novel mA-dependent regulatory axis in AMs that mediates ECM remodeling and alveolar injury in ARDS. Importantly, they suggest that FTO and its downstream effectors may serve as viable therapeutic targets to mitigate disease progression.