Diabetic cardiomyopathy is a common complication in patients with diabetes and is associated with underlying chronic inflammation and cardiac cell death, subsequently leading to heart failure (HF). ELAV-like protein 1 (ELAVL1) plays a critical role in the progression of inflammation and HF. However the role of ELAVL-1 in inflammation induced cardiac cell death (pyroptosis) under hyper glycemic condition remains elusive. Our data demonstrates that ELAVL1 expression augmented with a concomitant increase in caspase-1 and IL-1 beta expression in human hearts and human ventricular cardiomyocytes under hyperglycemic condition. Furthermore, ELAVL1 knockdown abrogates TNF-α induced canonical pyroptosis via NLRP3, caspase-1 and IL-1beta suppression. Bioinformatics analysis and target validation assays showed that miR-9 directly targets ELAVL1. Interestingly, miRNA-9 expression significantly reduced in high glucose treated cardiomyocytes and in human diabetic hearts. Inhibition of miR-9 upregulates ELAVL1 expression and activates caspase-1. Alternatively, treatment with miR-9 mimics attenuates hyperglycemia-induced ELAVL1 and inhibits cardiomyocyte pyroptosis. Taken together our study highlights the potential therapeutic implications of targeting miR-9/ELAVL1 in preventing cardiomyocyte cell loss during HF in diabetics.

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Background Micro ribonucleic acid (miR) dysregulation in the myocardium has been implicated in cardiac remodeling after injury or stress. Objectives This study sought to explore the role of miR in human CD34+ cell (hCD34+) dysfunction in vivo after transplantation into the myocardium under ischemia-reperfusion (I-R) conditions. Methods In response to inflammatory stimuli, the miR array profile of endothelial progenitor cells (EPC) was analyzed using a polymerase chain reaction-based miR microarray. MiR-377 expression was assessed in myocardial tissue from human patients with heart failure (HF). We investigated the effect of miR-377 inhibition on hCD34+ cell angiogenic proteome profile, in vitro and on cardiac repair and function after I-R injury in immunodeficient mice. Results The miR array data from EPCs in response to inflammatory stimuli indicate changes in numerous miR with a robust decrease in miR-377. Human cardiac biopsies from HF patients showed significant increase in miR-377 expression compared to nonfailing control hearts. Proteome profile of hCD34+ cells transfected with miR-377 mimics showed significant decrease in proangiogenic proteins versus nonspecific control transfected cells. We also validated that serine/threonine kinase 35 is a target of miR-377 using a dual-luciferase reporter assay. In a mouse model of myocardial I-R, intramyocardial transplantation of miR-377-silenced hCD34+ cells in immunodeficient mice, promoting neovascularization (at 28 days, post-I-R) and lower interstitial fibrosis, leading to improved left ventricular (LV) function. Conclusions These findings indicate that HF increases miR-377 in the myocardium, which is detrimental to stem cell function, and transplantation of miR-377 knockdown hCD34+ cells into ischemic myocardium promoted their angiogenic ability, attenuating LV remodeling and cardiac fibrosis.

Efferocytosis, a process of clearance of apoptotic cells by phagocytes, is essential for successful resolution of inflammation and maintenance of tissue homeostasis. Diabetes compromises the function of macrophages leading to adverse inflammatory response during wound healing, myocardial injury, atherosclerosis and autoimmune disorders. However, the effect of diabetes on macrophage-mediated efferocytosis of apoptotic cardiomyocytes (ACM) and the molecular mechanisms involved are not understood so far. In the present study we found that invitro efferocytosis of ACM was impaired in macrophages from db/db (diabetic) mice. Macrophages exposed to high glucose (HG) decreases microRNA-126 (miR-126) expression with a corresponding increase in ADAM9 expression. Dual-luciferase reporter assay confirms that ADAM9 3′UTR contains miR-126 target site. ADAM9 inhibition reduces HG-induced proteolytic cleavage of Mer tyrosine receptor kinase (MerTK, a proto-oncogene that plays a critical role in phagocytosis), resulting in shedding of soluble-Mer (sMER) and loss of MERTK function. Over-expression of miR-126 attenuates HG-induced impairment of efferocytosis. Furthermore, human diabetic hearts show lower miR-126 expression with a corresponding increase in ADAM9 expression vs. normal counterparts. These data suggests that diabetes impairs efferocytosis of ACM and that strategies to enhance efferocytosis might attenuate diabetes-induced impairment in inflammation resolution and cardiac repair after injury.

Cardiac diseases are the predominant cause of human mortality in the United States and around the world. MicroRNAs (miRNAs) are small non-coding RNAs that have been shown to modulate a wide range of biological functions under various pathophysiological conditions. miRNAs alter target expression by post-transcriptional regulation of gene expression. Numerous studies have implicated specific miRNAs in cardiovascular development, pathology, regeneration and repair. These observations suggest that miRNAs are potential therapeutic targets to prevent or treat cardiovascular diseases. This review focuses on the emerging role of miRNAs in cardiac development, pathogenesis of cardiovascular diseases, cardiac regeneration and stem cell-mediated cardiac repair. We also discuss the novel diagnostic and therapeutic potential of these miRNAs and their targets in patients with cardiac diseases.

BackgroundExposure of vascular smooth muscle cells (VSMCs) to excessive cyclic stretch such as in hypertension causes a shift in their phenotype. The focal adhesion protein zyxin can transduce such biomechanical stimuli to the nucleus of both endothelial cells and VSMCs, albeit with different thresholds and kinetics. However, there is no distinct vascular phenotype in young zyxin-deficient mice, possibly due to functional redundancy among other gene products belonging to the zyxin family. Analyzing zyxin function in VSMCs at the cellular level might thus offer a better mechanistic insight. We aimed to characterize zyxin-dependent changes in gene expression in VSMCs exposed to biomechanical stretch and define the functional role of zyxin in controlling the resultant VSMC phenotype.Methods and ResultsDNA microarray analysis was used to identify genes and pathways that were zyxin regulated in static and stretched human umbilical artery–derived and mouse aortic VSMCs. Zyxin-null VSMCs showed a remarkable shift to a growth-promoting, less apoptotic, promigratory and poorly contractile phenotype with ≈90% of the stretch-responsive genes being zyxin dependent. Interestingly, zyxin-null cells already seemed primed for such a synthetic phenotype, with mechanical stretch further accentuating it. This could be accounted for by higher RhoA activity and myocardin-related transcription factor-A mainly localized to the nucleus of zyxin-null VSMCs, and a condensed and localized accumulation of F-actin upon stretch.ConclusionsAt the cellular level, zyxin is a key regulator of stretch-induced gene expression. Loss of zyxin drives VSMCs toward a synthetic phenotype, a process further consolidated by exaggerated stretch.

Vascular cells respond to supraphysiological amounts of stretch with a characteristic phenotypic change that results in dysfunctional remodeling of the affected arteries. Although the pathophysiological consequences of stretch-induced signaling are well characterized, the mechanism of mechanotransduction is unclear. We focused on the mechanotransducer zyxin, which translocates to the nucleus to drive gene expression in response to stretch. In cultured human endothelial cells and perfused femoral arteries isolated from wild-type and several knockout mouse strains, we characterized a multistep signaling pathway whereby stretch led to a transient receptor potential channel 3-mediated release of the endothelial vasoconstrictor peptide endothelin-1 (ET-1). ET-1, through autocrine activation of its B-type receptor, elicited the release of pro-atrial natriuretic peptide (ANP), which caused the autocrine activation of the ANP receptor guanylyl cyclase A (GC-A). Activation of GC-A, in turn, led to protein kinase G-mediated phosphorylation of zyxin at serine 142, thereby triggering the translocation of zyxin to the nucleus, where it was required for stretch-induced gene expression. Thus, we have identified a stretch-induced signaling pathway in vascular cells that leads to the activation of zyxin, a cytoskeletal protein specifically involved in transducing mechanical stimuli.

Delayed wound healing is one of the major complications in diabetes and is characterized by chronic proinflammatory response, and abnormalities in angiogenesis and collagen deposition. Sirtuin family proteins regulate numerous pathophysiological processes, including those involved in promotion of longevity, DNA repair, glycolysis and inflammation. However the role of sirtuin 6 (SIRT6), a NAD+-dependent nuclear deacetylase, in wound healing specifically under diabetic condition remains unclear. To analyze the role of SIRT6 in cutaneous wound healing, paired 6 mm stented wound were created in diabetic db/db mice and injected siRNA against SIRT6 in the wound margins (transfection agent alone and non-sensed siRNA served as controls). Wound time to closure was assessed by digital planimetry, and wounds were harvested for histology, immunohistochemistry and Western blotting. SIRT6-siRNA treated diabetic wound showed impaired healing, which was associated with reduced capillary density (CD31 staining vessels) when compared to control treatment. Interestingly, SIRT6 deficiency decreased vascular endothelial growth factor (VEGF) expression and proliferation markers in the wounds. Furthermore, SIRT6 ablation in diabetic wound promotes nuclear factor kB (NF-kB) activation resulting in increased expression of proinflammatory markers (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, tumor necrosis factor-α and interleukin-1β) and increased oxidative stress. Collectively, our findings demonstrate that loss of SIRT6 in cutaneous wound aggravates proinflammatory response by increasing NF-kB activation, oxidative stress and decrease in angiogenesis in the diabetic mice. Based on these findings, we speculate that activation of SIRT6 signaling might be a potential therapeutic approach for promoting wound healing in diabetics.