Masante, L. | Search bioRxiv

bioRxiv2026

Insulin synthesis is sustained by Tent5 poly(A) polymerases

Insulin is an essential regulator of glucose homeostasis in vertebrates, and impairment of its synthesis or action leads to diabetes with severe health complications in humans. It is therefore essential to understand how beta cells control insulin synthesis and secretion, including the transcription, translation and decay of its messenger RNA. Using sequencing-based poly(A) tail length profiling from human tissue, genetic evidence for type 2 diabetes, bulk and single-cell transcriptomics and perturbation experiments, here we find that the insulin mRNA is stabilized by the activity of noncanonical poly(A) polymerases of the Tent5 family. We show that Tent5 activity is specific, promoted by both localization at the endoplasmic reticulum and regulatory sequences within the insulin mRNA and regulated by glucose. Overall, our findings provide a mechanistic link between the dynamic control of insulin production by beta cells and the direct regulation of insulin mRNA metabolism.

molecular biology↗

bioRxiv2023

Short 2'-O-methyl/LNA oligomers as highly-selective inhibitors of miRNA production in vitro and in vivo

MicroRNAs (miRNAs) that share identical or near-identical sequences constitute miRNA families and are predicted to act redundantly. Yet recent evidence suggests that members of the same miRNA family with high sequence similarity might have different roles and that this functional divergence might be rooted in their precursors sequence. Current knock-down strategies such as antisense oligonucleotides (ASOs) or miRNA sponges cannot distinguish between identical or near identical miRNAs originating from different precursors to allow exploring unique functions of these miRNAs. We now develop a method based on short 2'-OMe/LNA-modified oligonucleotides to selectively target specific precursor molecules and ablate the production of individual members of miRNA families in vitro and in vivo. Using the highly conserved Xenopus miR-181a family as a proof-of-concept, we demonstrate that 2'-OMe/LNA-ASOs targeting pre-miRNA apical region elicit a precursor-selective inhibition of mature miRNA-5p production. The levels of miRNAs released from the 3'-arm of these precursors are not reduced, suggesting that our approach is also arm-selective. Overall, we show that this strategy can be successfully applied in vivo to achieve high target selectivity to study identical or highly similar miRNAs stemming from different precursors.

molecular biology↗