Transcriptome-Wide N7-Methylguanosine (m7G) Map Profiling Reveals the Regulatory Role of m7G in Atherosclerosis

The uptake of modified lipoproteins by macrophages to form foam cells is a crucial step in atherosclerosis (AS) development. N7-methylguanosine (m7G) is frequently methylated internally in eukaryotic RNA transcripts and plays a crucial role in various processes. This study aimed to investigate the m7G RNA methylation profile in AS. We employed high-throughput sequencing to analyze the m7G methylome in foam cells induced by ox-LDL, using an in vitro AS model. Then, m7G-seq, RNA-seq, bioinformatic analysis, cell biological analyses, followed by qRT-PCR were performed. Additionally, the roles of SCARB2 and RASSF8 were investigated in an in vivo AS mouse model, and cells with SCARB2/RASSF8 overexpression/knockdown. In vitro and in vivo oil red O staining confirmed the successful establishment of the atherosclerotic foam cell and mouse models. We identified 1197 m7G peaks and 430 differentially expressed mRNAs during foam cell formation. Bioinformatics analyses revealed different m7G peaks associated with the gonadotropin-releasing hormone (GnRH) signaling pathway, cytoskeleton-dependent intracellular transport, and mitochondrial organization, regulating the processes of macrophage foaminess. Moreover, 28 key differentially expressed methylated genes were identified. m7G methyltransferases (WDR4, METTL1, WBSCR22) were upregulated in the AS cell model, and m7G modification genes (SCARB2 and RASSF8) associated with pathological processes were confirmed. Immunofluorescence staining showed that RASSF8 and SCARB2 were both expressed in AS mice plaque tissues. Finally, RASSF8/SCARB2 overexpression could promote apoptosis and lipid accumulation of ox-LDL-induced RAW264.7 cells. An m7G transcriptome-wide map of AS in vitro was created, and the differentially m7G methylated genes SCARB2 and RASSF8 may be crucial in macrophage foaminess. Our findings offer novel insights into the underlying mechanisms and potential treatments for AS.