Calcineurin/NFATc2 and PI3K/AKT signaling maintains β-cell identity and function during metabolic and inflammatory stress
Carly M. Darden,
Srividya Vasu,
Jordan Mattke,
Yang Liu,
Christopher J. Rhodes,
Bashoo Naziruddin,
Michael C. Lawrence
Affiliations
Carly M. Darden
Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA; Institute of Biomedical Studies, Baylor University, Waco, TX 76706, USA
Srividya Vasu
Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA
Jordan Mattke
Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA; Institute of Biomedical Studies, Baylor University, Waco, TX 76706, USA
Yang Liu
Annette C. and Harold C. Simmons Transplant Institute, Baylor University Medical Center, Dallas, TX 75246, USA
Christopher J. Rhodes
Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes & Metabolism, University of Chicago, Chicago, IL 60637, USA; Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca Ltd, Gaithersburg, MD 20878, USA
Bashoo Naziruddin
Annette C. and Harold C. Simmons Transplant Institute, Baylor University Medical Center, Dallas, TX 75246, USA
Michael C. Lawrence
Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA; Corresponding author
Summary: Pancreatic islets respond to metabolic and inflammatory stress by producing hormones and other factors that induce adaptive cellular and systemic responses. Here we show that intracellular Ca2+ ([Ca2+]i) and ROS signals generated by high glucose and cytokine-induced ER stress activate calcineurin (CN)/NFATc2 and PI3K/AKT to maintain β-cell identity and function. This was attributed in part by direct induction of the endocrine differentiation gene RFX6 and suppression of several β-cell “disallowed” genes, including MCT1. CN/NFATc2 targeted p300 and HDAC1 to RFX6 and MCT1 promoters to induce and suppress gene transcription, respectively. In contrast, prolonged exposure to stress, hyperstimulated [Ca2+]i, or perturbation of CN/NFATc2 resulted in downregulation of RFX6 and induction of MCT1. These findings reveal that CN/NFATc2 and PI3K/AKT maintain β-cell function during acute stress, but β-cells dedifferentiate to a dysfunctional state upon loss or exhaustion of Ca2+/CN/NFATc2 signaling. They further demonstrate the utility of targeting CN/NFATc2 to restore β-cell function
