9-OR: ADA Presidents' Select Abstract: m6A mRNA Methylation Regulates the Innate Immune Response in Human Beta Cells

Abstract

Innate immunity is directly associated with Type 1 diabetes (T1D) . Recently, N6-methyladenosine (m6A) has been shown to modulate human β-cell biology and innate immunity. Here, we focused on the contribution of m6A in modulating T1D development. RNA-seq. in β-cells revealed downregulation of the m6A writers (Mettl3, Mettl14, and Wtap) in pre-diabetic NOD mice. Consistently, pancreases from female NOD mice and human T1D showed downregulation of METTL3 protein levels in insulin-positive cells as the disease progressed. m6A-sequencing in human T1D versus control islets and intersection with differentially expressed genes (DEGs) in T1D β-cells from a single-cell RNA seq. dataset, revealed enriched pathways associated with ER function, T1D, and apoptosis. Pro-inflammatory cytokines are directly linked to β-cell autoimmunity and are considered a useful tool to study T1D onset. We applied m6A-sequencing in cytokine-treated human islet preparations, and in parallel studies, treated EndoC-βH1 cells with cytokines followed by RNA-sequencing. Intersection of m6A-decorated and common DEGs in human islets and EndoC-βH1 cells revealed enrichment in pathways associated with the innate immune response. METTL3 silencing in EndoC-βH1 impacted several innate immune mediators upon cytokine challenge. Incubation of human islets from multiple donors with ER-stress inducers, ROS donors, NO donors, and ROS or NO scavengers revealed that pre-existing ER stress and ROS decrease METTL3, while physiological levels of NO upregulate METTL3. We conclude that ROS drives METTL3 downregulation associated with T1D. Exploring therapeutic relevance by AAV-8 mediated gene delivery showed that β-cell specific upregulation of Mettl3 leads to a decrease in hyperglycemia during early stages of T1D in female NOD mice. Together, these results demonstrate a novel layer of regulation in human β-cells in the context of T1D and point to targeting METTL3 as a therapeutic approach to promote β-cell survival and improve glycemia. Disclosure D.F.De jesus: n/a. D.L.Eizirik: None. R.Kulkarni: Advisory Panel; Biomea, Novo Nordisk, REDD Pharma, Consultant; Relay Therapeutics, Research Support; Inversago, SerPlus. Z.Zhang: Research Support; SinoVac. N.K.Brown: None. G.Basile: None. L.Xiao: None. S.Kahraman: Employee; Boehringer Ingelheim International GmbH. C.E.Mathews: None. A.C.Powers: None. M.A.Atkinson: None. Funding American Diabetes Association (7-21-PDF-140) ; R01 DK067536R01 DK103215R01 DK117639