biostudies-literatureUnknown9(40)Bui CVSeveral genetically encoded sensors have been developed to study live cell NADPH/NADP⁺ dynamics, but their use has been predominantly in vitro. Here, we developed an in vivo assay using the Apollo-NADP⁺ sensor and microfluidic devices to measure endogenous NADPH/NADP⁺ dynamics in the pancreatic β cells of live zebrafish embryos. Flux through the pentose phosphate pathway, the main source of NADPH in many cell types, has been reported to be low in β cells. Thus, it is unclear how these cells compensate to meet NADPH demands. Using our assay, we show that pyruvate cycling is the main source of NADP⁺ reduction in β cells, with contributions from folate cycling after acute electrical activation. INS1E β cells also showed a stress-induced increase in folate cycling and further suggested that this cycling requires both increased glycolytic intermediates and cytosolic NAD⁺. Overall, we show in vivo application of the Apollo-NADP⁺ sensor and reveal that β cells are capable of adapting NADPH/NADP⁺ redox during stress.Science advanceseadi8317https://www.ebi.ac.uk/biostudies/studies/S-EPMC10550227biostudies-literatureApollo-NADP⁺ reveals in vivo adaptation of NADPH/NADP⁺ metabolism in electrically activated pancreatic β cells.PMC10550227Boswell CWCiruna BBui CVRocheleau JVfalseApollo-NADP⁺ reveals in vivo adaptation of NADPH/NADP⁺ metabolism in electrically activated pancreatic β cells.Several genetically encoded sensors have been developed to study live cell NADPH/NADP⁺ dynamics, but their use has been predominantly in vitro. Here, we developed an in vivo assay using the Apollo-NADP⁺ sensor and microfluidic devices to measure endogenous NADPH/NADP⁺ dynamics in the pancreatic β cells of live zebrafish embryos. Flux through the pentose phosphate pathway, the main source of NADPH in many cell types, has been reported to be low in β cells. Thus, it is unclear how these cells compensate to meet NADPH demands. Using our assay, we show that pyruvate cycling is the main source of NADP⁺ reduction in β cells, with contributions from folate cycling after acute electrical activation. INS1E β cells also showed a stress-induced increase in folate cycling and further suggested that this cycling requires both increased glycolytic intermediates and cytosolic NAD⁺. Overall, we show in vivo application of the Apollo-NADP⁺ sensor and reveal that β cells are capable of adapting NADPH/NADP⁺ redox during stress.2023-01-01T00:00:00Z2023 Oct2025-04-18T13:25:05.347Z2025-04-04T08:46:11.499ZS-EPMC105502273779293410.1126/sciadv.adi8317