P66Shc Mediates SUMO2-induced Endothelial Dysfunction.

Sumoylation is a post-translational modification that can regulate different physiological functions. Increased sumoylation, specifically conjugation of SUMO2/3 (small ubiquitin like modifier 2/3), is detrimental to vascular health. However, the molecular mechanism mediating this effect is poorly understood. Here, we demonstrate that SUMO2 modifies p66Shc, which impairs endothelial function. Using multiple approaches, we show that p66Shc is a direct target of SUMO2. Mass spectrometry identified that SUMO2 modified lysine-81 in the unique collagen homology-2 domain of p66Shc. SUMO2ylation of p66Shc increased phosphorylation at serine-36, causing it to translocate to the mitochondria. Notably, sumoylation-deficient p66Shc (p66ShcK81R) was resistant to SUMO2-induced p66ShcS36 phosphorylation and mitochondrial translocation. Ingenuity pathway analysis showed that majority of effects of p66Shc SUMO2ylation were mediated via p66ShcK81. Finally, p66ShcK81R knockin mice were resistant to SUMO2-induced endothelial dysfunction. Collectively, our work uncovers a posttranslational modification of redox protein p66Shc and identifies SUMO2-p66Shc signaling as a regulator of vascular endothelial function.

Human microbiome and cardiovascular diseases.

A number of microorganisms are co-evolved with the host, among which bacteria are the predominant organisms in the colonic site. The human microbiota contributes to various physiological functions, including the digestion and degradation of food components, harvesting of inaccessible nutrients, immune system regulation, maintenance of gut barrier function, and regulation of brain function and behavior. Microbes in the gut produce a wealth of metabolites from the exogenous dietary substances or endogenous metabolic compounds produced by the host and the resident microorganisms. These microbial-derived metabolites are the major factors in the host-microbiota cross-talk and influence the host's cardiometabolic health directly or indirectly depending on the structure and function of the microbial community. Evidence suggests that the perturbation in the composition and function of gut microbiota (referred to as gut dysbiosis) is associated with the development of several diseased conditions such as that of the gastrointestinal tract or colorectal cancer, metabolic diseases such as obesity, diabetes, immune disorders e.g. asthma, allergies, depression, anxiety and cardiometabolic disease. Several pathological conditions in the gastrointestinal tract may impair the intestinal barrier that allows translocation of bacteria and their metabolites to a remote organ such as the heart, which may ultimately be associated with systemic inflammation and the development of CVDs. In this chapter, we will discuss various gut microbiota-dependent metabolites, which have a significant role in cardiovascular diseases' pathologic processes and their risk factors. Finally, we will discuss the therapeutic potential of the gut-metabolite-heart axis as a novel target for the treatment of CVD and highlight the current updates and exciting directions for future research.

Role of GSK-3 in Cardiac Health: Focusing on Cardiac Remodeling and Heart Failure.

Glycogen synthase kinase 3 (GSK-3) is a ubiquitously expressed serine/threonine kinase and was first identified as a regulator of glycogen synthase enzyme and glucose homeostasis. It regulates cellular processes like cell proliferation, metabolism, apoptosis and development. Recent findings suggest that GSK-3 is required to maintain the normal cardiac homeostasis that regulates cardiac development, proliferation, hypertrophy and fibrosis. GSK-3 is expressed as two isoforms, α and ß. The role of GSK-3α and GSK-3ß in cardiac biology is well documented. Both isoforms have common as well as isoform-specific functions. Human data also suggests that GSK-3ß is downregulated in hypertrophy and heart failure and acts as a negative regulator. Pharmacological inhibition of GSK-3α and GSK-3ß leads to endogenous cardiomyocyte proliferation and cardiac regeneration via the upregulation of cell cycle regulators, which results in cell cycle re-entry and DNA synthesis. It was found that cardiac-specific knockout (KO) of GSK-3α retained cardiac function, inhibited cardiovascular remodelling and restricted scar expansion during ischemia. Further, knockout of GSK-3α decreases cardiomyocyte apoptosis and enhances its proliferation. However, GSK-3ß KO also results in hypertrophic myopathy due to cardiomyocyte hyper-proliferation. Thus GSK-3 inhibitors are named as a double-edged sword because of their beneficial and off-target effects. This review focuses on the isoform-specific functions of GSK-3 that will help in better understanding the role of GSK-3α and GSK-3ß in cardiac biology and pave the way for the development of new isoform-specific GSK-3 modulator for the treatment of ischemic heart disease, cardiac regeneration and heart failure.

Understanding the Activation of Platelets in Diabetes and Its Modulation by Allyl Methyl Sulfide, an Active Metabolite of Garlic.

BACKGROUND: Diabetes mellitus (DM) is a chronic metabolic disorder associated with higher risk of having cardiovascular disease. Platelets play a promising role in the pathogenesis of cardiovascular complications in diabetes. Since last several decades, garlic and its bioactive components are extensively studied in diabetes and its complications. Our aim was to explore the antiplatelet property of allyl methyl sulfide (AMS) focusing on ameliorating platelet activation in diabetes. METHOD: We used streptozotocin- (STZ-) induced diabetic rats as model for type 1 diabetes. We have evaluated the effect of allyl methyl sulfide on platelet activation by administrating AMS to diabetic rats for 10 weeks. Flow cytometry-based analysis was used to evaluate the platelet activation, platelet aggregation, platelet macrophage interaction, and endogenous ROS generation in the platelets obtained from control, diabetes, and AMS- and aspirin-treated diabetic rats. RESULTS: AMS treatment for 10 weeks effectively reduced the blood glucose levels in diabetic rats. Three weeks of AMS (50 mg/kg/day) treatment did not reduce the activation of platelets but a significant (p < 0.05) decrease was observed after 10 weeks of treatment. Oral administration of AMS significantly (p < 0.05) reduced the baseline and also reduced ADP-induced aggregation of platelets after 3 and 10 weeks of treatment. Furthermore, 10 weeks of AMS treatment in diabetic rats attenuated the endogenous ROS content (p < 0.05) of platelets and platelet macrophage interactions. The inhibition of platelet activation in diabetic rats after AMS treatment was comparable with aspirin treatment (30 mg/kg/day). CONCLUSION: We observed an inhibitory effect of allyl methyl sulfide on platelet aggregation, platelet activation, platelet macrophage interaction, and increased ROS levels in type 1 diabetes. Our data suggests that AMS can be useful to control cardiovascular complication in diabetes via inhibition of platelet activation.