O-GlcNAcylation of Histone Deacetylase 4 Protects the Diabetic Heart From Failure

Abstract

Background: Worldwide, diabetes mellitus and heart failure represent frequent comorbidities with high socioeconomic impact and steadily growing incidence, calling for a better understanding of how diabetic metabolism promotes cardiac dysfunction. Paradoxically, some glucose-lowering drugs have been shown to worsen heart failure, raising the question of how glucose mediates protective versus detrimental cardiac signaling. Here, we identified a histone deacetylase 4 (HDAC4) subdomain as a molecular checkpoint of adaptive and maladaptive signaling in the diabetic heart. Methods: A conditional HDAC4 allele was used to delete HDAC4 specifically in cardiomyocytes (HDAC4-knockout). Mice were subjected to diabetes mellitus either by streptozotocin injections (type 1 diabetes mellitus model) or by crossing into mice carrying a leptin receptor mutation (db/db; type 2 diabetes mellitus model) and monitored for remodeling and cardiac function. Effects of glucose and the posttranslational modification by β-linked N -acetylglucosamine (O-GlcNAc) on HDAC4 were investigated in vivo and in vitro by biochemical and cellular assays. Results: We show that the cardio-protective N-terminal proteolytic fragment of HDAC4 is enhanced in vivo in patients with diabetes mellitus and mouse models, as well as in vitro under high-glucose and high–O-GlcNAc conditions. HDAC4-knockout mice develop heart failure in models of type 1 and type 2 diabetes mellitus, whereas wild-type mice do not develop clear signs of heart failure, indicating that HDAC4 protects the diabetic heart. Reexpression of the N-terminal fragment of HDAC4 prevents HDAC4-dependent diabetic cardiomyopathy. Mechanistically, the posttranslational modification of HDAC4 at serine (Ser)-642 by O-GlcNAcylation is an essential step for production of the N-terminal fragment of HDAC4, which was attenuated by Ca 2+ /calmodulin–dependent protein kinase II–mediated phosphorylation at Ser-632. Preventing O-GlcNAcylation at Ser-642 not only entirely precluded production of the N-terminal fragment of HDAC4 but also promoted Ca 2+ /calmodulin–dependent protein kinase II–mediated phosphorylation at Ser-632, pointing to a mutual posttranslational modification cross talk of (cardio-detrimental) phosphorylation at Ser-632 and (cardio-protective) O-GlcNAcylation at Ser-642. Conclusions: In this study, we found that O-GlcNAcylation of HDAC4 at Ser-642 is cardio-protective in diabetes mellitus and counteracts pathological Ca 2+ /calmodulin–dependent protein kinase II signaling. We introduce a molecular model explaining how diabetic metabolism possesses important cardio-protective features besides its known detrimental effects. A deeper understanding of the here-described posttranslational modification cross talk may lay the groundwork for the development of specific therapeutic concepts to treat heart failure in the context of diabetes mellitus.

An Important Role for DNMT3A-Mediated DNA Methylation in Cardiomyocyte Metabolism and Contractility

“… 5 – 7 Methylation of cytosines in the context of so-called CpG islands, regions of high cytosine-guanidine dinucleotide density often found in promoter regions of genes, is typically associated with a change in expression of genes in close proximity, for example by interference with transcription factor binding or recruitment of repressor complexes. 8 However, whereas a contribution of other epigenetic marks such as histone modifications to cardiac disease progression has already been firmly established, 9 – 13 the role of DNA methylation remains controversial. DNA methylation analysis in patients experiencing end-stage heart failure or dilated cardiomyopathy showed distinct methylation patterns in diseased individuals compared with healthy controls.…”

Acute Increase in O-GlcNAc Improves Survival in Mice With LPS-Induced Systemic Inflammatory Response Syndrome

“…Hence, OGT and OGA expression and activity are important to regulate O-GlcNAc and, consequently, proteins function by changing their subcellular localization, activity, and interaction with other proteins (Andrali et al, 2007;Guinez et al, 2011;Baudoin and Issad, 2015;Zachara, 2018). In the cardiovascular system, O-GlcNAc modulates cardiac and vascular contractility and remodeling as well as inflammation-related processes (da Costa et al, 2018;Kronlage et al, 2019). Glucosamine, which increases O-GlcNAc-modified proteins, reduces the levels of circulating pro-inflammatory cytokines, including TNF-α and IL-6 (Azuma et al, 2015) and attenuates LPS-induced activation of NF-κB in RAW264.7 macrophages (Shin et al, 2013).…”

Four Dimensions of the Cardiac Myocyte Epigenome: from Fetal to Adult Heart

“…In adult mouse cardiac myocyte nuclei, 60.8% of nuclear mRNAs were unspliced as compared with only 2.6% unspliced mRNAs in intact cardiac myocyte cells [23••]. Cellular to nuclear mRNA expression ratios differed by a factor of 2 16 for all expressed genes, indicating a high degree of posttranscriptional alteration of transcript levels in cardiac myocytes [23••]. In total, 12,653 mRNAs were found to be expressed in adult mouse ventricular cardiac myocytes reflecting 63% of all coding genes in the mouse genome [23••].…”

“…Development, growth and the response to injury of cardiac myocytes are controlled by transcription factors, which orchestrate cardiac myocyte gene expression in close interaction with multiple layers of epigenetic regulation [13•, 14••, [15][16][17][18][19][20][21]. Essential epigenetic mechanisms modulating physiological and pathological gene expression include chromatin remodelling, histone modifications, DNA methylation and non-coding RNAs [22].…”