Project Summary Genetic and environmental factors play important roles in the etiology of diabetes. How these factors interact to promote disease remains unclear. N6-methyladenosine (m6A) is a dynamic mRNA modification that can direct splicing fate and stabilization, promote translation of mRNAs, and integrate nutritional information. Drosophila melanogaster, flies, with lowered levels of m6A in insulin-producing cells (IPCs) are diabetic; this phenotype is exacerbated by exposure to a nutrient-rich diet. mRNAs that encode proteins in the insulin system are methylated in the brain of flies. These results suggest that m6A plays a critical role in the insulin system. Yet, the mechanisms through which m6A contributes to the development of diabetes are unknown. The power of Drosophila genetics, the anatomy of the IPCs, the relative simplicity of the system, and the recent development of direct RNA-sequencing will be leveraged to uncover mechanisms through which m6A controls gene expression in IPCs. The central hypothesis is that reduced m6A in IPCs impairs necessary dynamic translational control over the insulin system. Aims 1 and 2 (K99) will focus on cell-intrinsic mechanisms that are sensitive to the loss of m6A regulation. These will uncover cell biological properties that depend on m6A for proper insulin output. Aims 2 and 4 (R00) will probe cell-extrinsic factors, which require m6A, that integrate external inputs. These will elucidate how m6A impacts insulin receptor translation and how the levels of m6A respond to nutritional state. Together, this proposed work will define a role for m6A methylation of mRNA in the function of IPCs and reveal how metabolic inputs modulate m6A control over mRNAs. This will advance our understanding of RNA control and may facilitate the discovery of therapeutic targets for diabetes prevention and therapy.