The identification of ‘secretory’ RNA-binding proteins (RBPs) provides evidence for a hitherto unknown link between gene expression and insulin exocytosis R Almomani1, R Wardman1, C Charoensuk1, T Sekaran2, T Schwarzl2, I Huppertz2, J Whitehead1, D Hodson3, M Hentze2, TP Herbert1 1School of Pharmacy and Life Sciences, University of Lincoln, Lincoln, UK; 2European Molecular Biology Laboratory, Heidelberg, Germany; 3Medical Sciences Division, University of Oxford, Oxford, UK Aims: The aims of the study were to identify global changes in the binding of RBPs to RNA in response to glucose in pancreatic beta cells, and then to determine the role of selected glucose-regulated RBPs in beta cell function. Methods: Experiments were performed using the mouse beta cell line, MIN6. Global identification of RBPs was determined using RNA interactome capture (RIC) and quantitative mass spectroscopy (SWATH-MS). Enhanced crosslinking immunoprecipitation (eCLIP) was used to identify RNAs bound to RBPs, and electrophoretic mobility shift assays (EMSA) and RNA immunoprecipitation (RIP) were used to confirm these findings. Results: Three hundred ninety-eight RBPs were identified of which the binding of 59 to RNAs were significantly modulated by glucose. Ontological analysis revealed an enrichment of non-canonical RBPs associated with membrane trafficking and exocytosis, which we have named ‘secretory-RBPs’. These included N-ethylmaleimide sensitive fusion protein (NSF) and vesicle-associated membrane protein 2 (VAMP2), whose binding to RNA was stimulated by glucose, driven by an increase in intracellular calcium. RNAs bound to NSF and VAMP2 were identified using eCLIP which demonstrated an enrichment of mRNAs encoding proteins associated with exocytosis, which was confirmed using EMSA and RIP. Conclusion: An increase in calcium promotes the coordinated recruitment of a subset of mRNAs to secretory-RBPs, which we hypothesise modulates their localisation and/or expression, thus revealing a hitherto unknown link between gene expression and insulin exocytosis. Support Information: This work was/is supported by the Diabetes Research and Wellness Foundation, the European Molecular Biology Organisation, the Leverhulme Trust, and Diabetes UK.