@article {510, title = {Sirtuin 1 regulates cardiac electrical activity by deacetylating the cardiac sodium channel.}, journal = {Nat Med}, year = {2017}, month = {2017 Feb 13}, abstract = {

The voltage-gated cardiac Na(+) channel (Nav1.5), encoded by the SCN5A gene, conducts the inward depolarizing cardiac Na(+) current (INa) and is vital for normal cardiac electrical activity. Inherited loss-of-function mutations in SCN5A lead to defects in the generation and conduction of the cardiac electrical impulse and are associated with various arrhythmia phenotypes. Here we show that sirtuin 1 deacetylase (Sirt1) deacetylates Nav1.5 at lysine 1479 (K1479) and stimulates INa via lysine-deacetylation-mediated trafficking of Nav1.5 to the plasma membrane. Cardiac Sirt1 deficiency in mice induces hyperacetylation of K1479 in Nav1.5, decreases expression of Nav1.5 on the cardiomyocyte membrane, reduces INa and leads to cardiac conduction abnormalities and premature death owing to arrhythmia. The arrhythmic phenotype of cardiac-Sirt1-deficient mice recapitulated human cardiac arrhythmias resulting from loss of function of Nav1.5. Increased Sirt1 activity or expression results in decreased lysine acetylation of Nav1.5, which promotes the trafficking of Nav1.5 to the plasma membrane and stimulation of INa. As compared to wild-type Nav1.5, Nav1.5 with K1479 mutated to a nonacetylatable residue increases peak INa and is not regulated by Sirt1, whereas Nav1.5 with K1479 mutated to mimic acetylation decreases INa. Nav1.5 is hyperacetylated on K1479 in the hearts of patients with cardiomyopathy and clinical conduction disease. Thus, Sirt1, by deacetylating Nav1.5, plays an essential part in the regulation of INa and cardiac electrical activity.

}, issn = {1546-170X}, doi = {10.1038/nm.4284}, author = {Vikram, Ajit and Lewarchik, Christopher M and Yoon, Jin-Young and Naqvi, Asma and Kumar, Santosh and Morgan, Gina M and Jacobs, Julia S and Li, Qiuxia and Kim, Young-Rae and Kassan, Modar and Liu, Jing and Gabani, Mohanad and Kumar, Ajay and Mehdi, Haider and Zhu, Xiaodong and Guan, Xiaoqun and Kutschke, William and Zhang, Xiaoming and Boudreau, Ryan L and Dai, Shengchuan and Matasic, Daniel S and Jung, Saet-Byel and Margulies, Kenneth B and Kumar, Vikas* and Bachschmid, Markus M and London, Barry and Irani, Kaikobad} } @article {511, title = {Sirtuin1-regulated lysine acetylation of p66Shc governs diabetes-induced vascular oxidative stress and endothelial dysfunction.}, journal = {Proc Natl Acad Sci U S A}, year = {2017}, month = {2017 Jan 30}, abstract = {

The 66-kDa Src homology 2 domain-containing protein (p66Shc) is a master regulator of reactive oxygen species (ROS). It is expressed in many tissues where it contributes to organ dysfunction by promoting oxidative stress. In the vasculature, p66Shc-induced ROS engenders endothelial dysfunction. Here we show that p66Shc is a direct target of the Sirtuin1 lysine deacetylase (Sirt1), and Sirt1-regulated acetylation of p66Shc governs its capacity to induce ROS. Using diabetes as an oxidative stimulus, we demonstrate that p66Shc is acetylated under high glucose conditions and is deacetylated by Sirt1 on lysine 81. High glucose-stimulated lysine acetylation of p66Shc facilitates its phosphorylation on serine 36 and translocation to the mitochondria, where it promotes hydrogen peroxide production. Endothelium-specific transgenic and global knockin mice expressing p66Shc that is not acetylatable on lysine 81 are protected from diabetic oxidative stress and vascular endothelial dysfunction. These findings show that p66Shc is a target of Sirt1, uncover a unique Sirt1-regulated lysine acetylation-dependent mechanism that governs the oxidative function of p66Shc, and demonstrate the importance of p66Shc lysine acetylation in vascular oxidative stress and diabetic vascular pathophysiology.

}, issn = {1091-6490}, doi = {10.1073/pnas.1614112114}, author = {Kumar, Santosh and Kim, Young-Rae and Vikram, Ajit and Naqvi, Asma and Li, Qiuxia and Kassan, Modar and Kumar, Vikas* and Bachschmid, Markus M and Jacobs, Julia S and Kumar, Ajay and Irani, Kaikobad} } @article {536, title = {Does reversible cysteine oxidation link the Western diet to cardiac dysfunction?}, journal = {FASEB J}, volume = {28}, year = {2014}, month = {2014 May}, pages = {1975-87}, abstract = {

Using a novel cysteine thiol labeling strategy coupled with mass spectrometric analysis, we identified and quantified the changes in global reversible cysteine oxidation of proteins in the left ventricle of hearts from mice with metabolic syndrome-associated diastolic dysfunction. This phenotype was induced by feeding a high-fat, high-sucrose, type-2 diabetogenic diet to C57BL/6J mice for 8 mo. The extent of reversible thiol oxidation in relationship to the total available (free and reducible) level of each cysteine could be confidently determined for 173 proteins, of which 98 contained cysteines differentially modified >=1.5-fold by the diet. Our findings suggest that the metabolic syndrome leads to potentially deleterious changes in the oxidative modification of metabolically active proteins. These alterations may adversely regulate energy substrate flux through glycolysis, β-oxidation, citric acid (TCA) cycle, and oxidative phosphorylation (oxphos), thereby contributing to maladaptive tissue remodeling that is associated with, and possibly contributing to, diastolic left ventricular dysfunction.

}, keywords = {Animals, Chromatography, Liquid, Citric Acid Cycle, Cysteine, Diet, Fatty Acids, Glycolysis, Heart Diseases, Male, Mice, Mice, Inbred C57BL, Myocardial Contraction, Myocardium, Obesity, Oxidative Phosphorylation, Oxygen, Phenotype, Protein Processing, Post-Translational, Proteomics, Reactive Nitrogen Species, Reactive Oxygen Species, Sulfhydryl Compounds, Tandem Mass Spectrometry}, issn = {1530-6860}, doi = {10.1096/fj.13-233445}, author = {Behring, Jessica B and Kumar, Vikas and Whelan, Stephen A and Chauhan, Pratibha and Siwik, Deborah A and Costello, Catherine E and Colucci, Wilson S and Cohen, Richard A and McComb, Mark E and Bachschmid, Markus M} }