Proinflammatory cytokines suppress nonsense-mediated RNA decay to impair regulated transcript isoform processing in pancreatic β cells

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Introduction: Proinflammatory cytokines are implicated in pancreatic ß cell failure in type 1 and type 2 diabetes and are known to stimulate alternative RNA splicing and the expression of nonsense-mediated RNA decay (NMD) components. Here, we investigate whether cytokines regulate NMD activity and identify transcript isoforms targeted in ß cells. Methods: A luciferase-based NMD reporter transiently expressed in rat INS1(832/13), human-derived EndoC-ßH3, or dispersed human islet cells is used to examine the effect of proinflammatory cytokines (Cyt) on NMD activity. The gain- or loss-of-function of two key NMD components, UPF3B and UPF2, is used to reveal the effect of cytokines on cell viability and function. RNA-sequencing and siRNA-mediated silencing are deployed using standard techniques. Results: Cyt attenuate NMD activity in insulin-producing cell lines and primary human ß cells. These effects are found to involve ER stress and are associated with the downregulation of UPF3B. Increases or decreases in NMD activity achieved by UPF3B overexpression (OE) or UPF2 silencing raise or lower Cyt-induced cell death, respectively, in EndoC-ßH3 cells and are associated with decreased or increased insulin content, respectively. No effects of these manipulations are observed on glucose-stimulated insulin secretion. Transcriptomic analysis reveals that Cyt increases alternative splicing (AS)-induced exon skipping in the transcript isoforms, and this is potentiated by UPF2 silencing. Gene enrichment analysis identifies transcripts regulated by UPF2 silencing whose proteins are localized and/or functional in the extracellular matrix (ECM), including the serine protease inhibitor SERPINA1/α-1-antitrypsin, whose silencing sensitizes ß-cells to Cyt cytotoxicity. Cytokines suppress NMD activity via UPR signaling, potentially serving as a protective response against Cyt-induced NMD component expression. Conclusion: Our findings highlight the central importance of RNA turnover in ß cell responses to inflammatory stress.

TidsskriftFrontiers in Endocrinology
Antal sider13
StatusUdgivet - 2024

Bibliografisk note

Funding Information:
Author GR is a consultant for, and has received grant funding from, Sun Pharmaceuticals Inc.

Funding Information:
The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by grants to SG from the Medical Council for Independent Research Fund Denmark (Independent Postdoctoral International Mobility, grant number: 9034-00001B) and the Society for Endocrinology (SfE) (SEF/2021/ICL-SMG), London, UK. GR was supported by a Wellcome Trust Investigator (WT212625/Z/18/Z) Award, an MRC (UKRI) Programme grant (MR/R022259/1), an NIH-NIDDK project grant (R01DK135268), a CIHR-JDRF Team grant (CIHR-IRSC TDP-186358 and JDRF 4-SRA-2023-1182-S-N), CRCHUM start-up funds, and an Innovation Canada John R. Evans Leader Award (CFI 42649). This project has received funding from the European Union’s Horizon 2020 research and innovation program via the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No. 115881 (RHAPSODY) to GR and PM. Provision of human islets from Milan was supported by JDRF award 31-2008-416 (ECIT Islet for Basic Research program). Acknowledgments

Publisher Copyright:
Copyright © 2024 Ghiasi, Marchetti, Piemonti, Nielsen, Porse, Mandrup-Poulsen and Rutter.

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