Introduction: The transcription factor ETV5 regulates various biological processes such as cell proliferation and apoptosis, and activates a whole string of obesity- and diabetes-related genes. ETV5 is involved in tissue protection since mice with pancreatic loss of Etv5 show increased severity of pancreatitis and delayed tissue recovery. Here, we investigate the role of Etv5 knockdown (KD) on survival of injured endocrine pancreatic beta cells.
Methods: We generated INS-1E beta cells with doxycycline (dox) -inducible lentiviral Etv5 sh-RNA knock-down (KD) . Cellular stress was induced by streptozotocin (STZ) and palmitate (PA) . We assessed viability (MTS) , apoptosis (caspases-3/7 activation) , necrosis (assay) , ER stress (BiP and CHOP gene expression) , oxidative stress (ROS production) and gene expression of SOD1, SOD2 and Catalase.
Results: Etv5 KD significantly increases STZ/PA-induced loss of viability without changes in apoptosis but with increased necrosis. Etv5 KD did not change STZ/PA-induced gene expression of ER stress markers BiP and CHOP but significantly increased H2O2 production. This was associated with significantly elevated gene expression of mitochondrial SOD2, which converts superoxide into H2O2. Cytoplasmatic SOD1 and H2O2-decomposing catalase, PRDX1 and GPx1 remained unaffected.
Conclusion: Increased circulating free fatty acids in obesity promote oxidative stress. Loss of ETV5 increases ROS production in mitochondria during cellular stress by PA and STZ, as indicated by upregulated SOD2 gene expression. This suggests a role for ETV5 in controlling mitochondrial oxidative stress in pancreatic β-cells.
X. Yi: None. G. Päth: None. J. Seufert: Advisory Panel; Abbott, Sanofi-Aventis Deutschland GmbH. Research Support; Boehringer Ingelheim International GmbH. Speaker's Bureau; Abbott Diabetes, AstraZeneca, Bayer AG, Boehringer Ingelheim International GmbH, Lilly, Novo Nordisk, Sanofi-Aventis Deutschland GmbH.
XY is supported by China Scolarship Council (CSC) China,GP received Projektförderung from the German Diabetes Society (DDG)