m6A modification of mutant huntingtin RNA promotes the biogenesis of pathogenic huntingtin transcripts

作者：Anika Pupak, Irene Rodríguez-Navarro, Kirupa Sathasivam, Ankita Singh, Amelie Essmann, Daniel del Toro, Sílvia Ginés, Ricardo Mouro Pinto, Gillian P. Bates, Ulf Andersson Ørom, Eulàlia Martı́, Verónica Brito · 发表于：EMBO Reports · 年份：2024 · DOI：10.1038/s44319-024-00283-7 · 被引用次数：8 · 研究领域：RNA modifications and cancer、RNA Research and Splicing、Cancer-related gene regulation

Abstract In Huntington’s disease (HD), aberrant processing of huntingtin ( HTT ) mRNA produces HTT1a transcripts that encode the pathogenic HTT exon 1 protein. The mechanisms behind HTT1a production are not fully understood. Considering the role of m 6 A in RNA processing and splicing, we investigated its involvement in HTT1a generation. Here, we show that m 6 A methylation is increased before the cryptic poly(A) sites (IpA1 and IpA2) within the huntingtin RNA in the striatum of Hdh+/Q111 mice and human HD samples. We further assessed m 6 A’s role in mutant Htt mRNA processing by pharmacological inhibition and knockdown of METTL3, as well as targeted demethylation of Htt intron 1 using a dCas13-ALKBH5 system in HD mouse cells. Our data reveal that Htt1a transcript levels are regulated by both METTL3 and the methylation status of Htt intron 1. They also show that m 6 A methylation in intron 1 depends on expanded CAG repeats. Our findings highlight a potential role for m 6 A in aberrant splicing of Htt mRNA.