Glucose and hypotonicity induced cell swelling stimulate insulin release from pancreatic β-cells but the mechanisms are poorly understood. Recently, Piezo1 was identified as a mechanically-activated nonselective Ca2+ permeable cationic channel in a range of mammalian cells. As cell swelling induced insulin release could be through stimulation of Ca2+ permeable stretch activated channels, we hypothesised a role for Piezo1 in cell swelling induced insulin release. Two rat β-cell lines (INS-1 and BRIN-BD11) and freshly-isolated mouse pancreatic islets were studied. Intracellular Ca2+ measurements were performed using the fura-2 Ca2+ indicator dye and ionic current was recorded by whole cell patch-clamp. Piezo1 agonist Yoda1, a competitive antagonist of Yoda1 (Dooku1) and an inactive analogue of Yoda1 (2e) were used as chemical probes. Piezo1 mRNA and insulin secretion were measured by RT-PCR and ELISA respectively. Piezo1 mRNA was detected in both β-cell lines and mouse islets. Yoda1 evoked Ca2+ entry was inhibited by Yoda1 antagonist Dooku1 as well as other Piezo1 inhibitors gadolinium and ruthenium red, and not mimicked by 2e. Yoda1, but not 2e, stimulated Dooku1-sensitive insulin release from β-cells and pancreatic islets. Hypotonicity and high glucose increased intracellular Ca2+ and enhanced Yoda1 Ca2+ influx responses. Yoda1 and hypotonicity induced insulin release were significantly inhibited by Piezo1 specific siRNA. Pancreatic islets from mice with haploinsufficiency of Piezo1 released less insulin upon exposure to Yoda1. The data show that Piezo1 channel agonist induces insulin release from β-cell lines and mouse pancreatic islets suggesting a role for Piezo1 in cell swelling induced insulin release. Hence Piezo1 agonists have the potential to be used as enhancers of insulin release.

COVID-19, caused by the SARS-CoV-2 virus, carries significant risk of mortality and has spread globally with devastating societal consequences. Endothelial infection has been identified as a feature of the disease and so there is motivation to determine the relevance of endothelial membrane mechanisms affecting viral entry and response. Here, through a study of patient data in UK Biobank released on 16 April 2020, we suggest relevance of PIEZO1, a non-selective cation channel protein that both mediates endothelial responses to mechanical force and unusually indents the cell membrane. PIEZO1 notably has roles that may also be relevant in red blood cell function, pulmonary inflammation, bacterial infection and fibrotic auto-inflammation. We provide evidence that single nucleotide polymorphisms (SNPs) in the gene encoding PIEZO1 are more common in individuals who test positive for SARS-CoV-2 regardless of pre-existing hypertension, myocardial infarction, stroke, diabetes mellitus or arthritis. Some of these SNPs are more common in African and Caribbean populations, which are groups that were recently shown to have greater susceptibility to infection. One of the SNPs is a missense mutation that results in an amino acid change in an evolutionarily conserved and previously unexplored N-terminal region PIEZO1. The data support the notion of genetic factors influencing SARS-CoV-2 infection and suggest a specific role for PIEZO1.

Objective: Glucose and hypotonicity induced cell swelling stimulate insulin release from pancreatic b-cells but the mechanisms are poorly understood. Recently, Piezo1 was identified as a mechanically-activated nonselective Ca 2+ permeable cationic channel in a range of mammalian cells. As cell swelling induced insulin release could be through stimulation of Ca 2+ permeable stretch activated channels, we hypothesised a role for Piezo1 in cell swelling induced insulin release. Methods:Two rat b-cell lines (INS-1 and BRIN-BD11) and freshly-isolated mouse pancreatic islets were studied. Intracellular Ca 2+ measurements were performed using the fura-2 Ca 2+ indicator dye. Piezo1 agonist Yoda1, a competitive antagonist of Yoda1 (Dooku1) and an inactive analogue of Yoda1 (2e) were used as chemical probes. Piezo1 mRNA and insulin secretion were measured by RT-PCR and ELISA respectively.Results: Piezo1 mRNA was detected in both b-cell lines and mouse islets. Yoda1 evoked Ca 2+ entry which was inhibited by Yoda1 antagonist Dooku1 as well as other Piezo1 inhibitors gadolinium and ruthenium red, and not mimicked by 2e. Yoda1, but not 2e, stimulated Dooku1-sensitive insulin release from b-cells and pancreatic islets. Hypotonicity and high glucose increased intracellular Ca 2+ and enhanced Yoda1 Ca 2+ influx responses. Pre-treatment with ruthenium red significantly reduced hypotonicity induced insulin release from b-cells and pancreatic islets. Conclusion:The data show that Piezo1 channel agonist induces insulin release from b-cell lines and mouse pancreatic islets suggesting a role for Piezo1 in cell swelling induced insulin release. Hence Piezo1 agonists have a potential to be used as enhancers of insulin release.