Hyperglycaemia-induced epigenetic changes drive persistent cardiac dysfunction via the adaptor p66Shc. (1st October 2018)

• Record Type: Journal Article
• Authors: Costantino, Sarah; Paneni, Francesco; Mitchell, Katharyn; Mohammed, Shafeeq A.; Hussain, Shafaat; Gkolfos, Christos; Berrino, Liberato; Volpe, Massimo; Schwarzwald, Colin; Lüscher, Thomas Felix; Cosentino, Francesco
• Is Part Of: International journal of cardiology. Volume 268(2018)
• Page Start: 179
• Page End: 186
• Publication Date: 2018-10-01
• Subjects: Epigenetics -- miRNAs -- miR-34a -- miR-218 -- Oxidative stress -- Diabetic cardiomyopathy; Cardiology -- Periodicals; Electronic journals; 616.12
• DOI: 10.1016/j.ijcard.2018.04.082
• Languages: English
• ISSNs: 0167-5273

Abstract

Abstract: Aims: Hyperglycaemia-induced reactive oxygen species (ROS) are key mediators of cardiac dysfunction. Intensive glycaemic control (IGC) has failed to reduce risk of heart failure in patients with diabetes but the underlying mechanisms remain to be elucidated. The present study investigates whether epigenetic regulation of the pro-oxidant adaptor p66 Shc contributes to persistent myocardial dysfunction despite IGC. Methods and results: p66 Shc expression was increased in the heart of diabetic mice, and 3-week IGC by slow-release insulin implants did not revert this phenomenon. Sustained p66 Shc upregulation was associated with oxidative stress, myocardial inflammation and left ventricular dysfunction, as assessed by conventional and 2D speckle-tracking echocardiography. In vivo gene silencing of p66 Shc, performed during IGC, inhibited ROS production and restored cardiac function. Furthermore, we show that dysregulation of methyltransferase DNMT3b and deacetylase SIRT1 causes CpG demethylation and histone 3 acetylation on p66 Shc promoter, leading to persistent transcription of the adaptor. Altered DNMT3b/SIRT1 axis in the diabetic heart was explained by upregulation of miR-218 and miR-34a. Indeed, in human cardiomyocytes exposed to high glucose, inhibition of these miRNAs restored the expression of DNMT3b and SIRT1 and erased the adverse epigenetic signatures on p66 Shc promoter. Consistently, reprogramming miR-218 and miR-34a attenuated persistent p66 Shc expression and ROS generation. Conclusions: In diabetic left ventricular dysfunction, a complex epigenetic mechanism linking miRNAs and chromatin modifying enzymes drives persistent p66 Shc transcription and ROS generation. Our results set the stage for pharmacological targeting of epigenetic networks to alleviate the clinical burden of diabetic cardiomyopathy. Highlights: Glycemic control does not affect p66Shc expression and oxidative stress in theheart of diabetic mice; Silencing of p66Shc, at the time of normoglycaemia restoration, blunts oxidative stress and restorescardiac function; DNA hypomethylation and H3 acetylation, were observed on p66Shc promoter of diabetic mice even after glycemic control; Downregulation of DNMT3b and SIRT1 cause these epigenetic changes on p66Shc promoter fostering gene upregulation; miR-218 and miR-34a, upstream regulators of DNMT3b/SIRT1, lead to persistent p66Shcupregulation in the diabetic heart.