Protein succination is a stable post-translational modification that occurs when fumarate reacts with cysteine residues to generate S-(2-succino)cysteine (2SC). We demonstrate that both alpha (α) and beta (β) tubulin are increasingly modified by succination in 3T3-L1 adipocytes and in the adipose tissue of db/db mice. Incubation of purified tubulin from porcine brain with fumarate (50 mM) or the pharmacological compound dimethylfumarate (DMF, 500 μM) inhibited polymerization up to 35% and 59%, respectively. Using mass spectrometry we identified Cys347α, Cys376α, Cys12β and Cys303β as sites of succination in porcine brain tubulin and the relative abundance of succination at these cysteines increased in association with fumarate concentration. The increase in succination after incubation with fumarate altered tubulin recognition by an anti-α-tubulin antibody. Succinated tubulin in adipocytes cultured in high glucose vs. normal glucose also had reduced reactivity with the anti-αtubulin antibody; suggesting that succination may interfere with tubulin:protein interactions. DMF reacted rapidly with 11 of the 20 cysteines in the αβ tubulin dimer, decreased the number of free sulfhydryls and inhibited the proliferation of 3T3-L1 fibroblasts. Our data suggests that inhibition of tubulin polymerization is an important, undocumented mechanism of action of DMF. Taken together, our results demonstrate that succination is a novel post-translational modification of tubulin and suggest that extensive modification by fumarate, either physiologically or pharmacologically, may alter microtubule dynamics.
S-(2-SuccinylWe show here that succination of protein is also increased in epididymal, mesenteric, and subcutaneous adipose tissue of diabetic (db/db) mice and that adiponectin is a major target for succination in both adipocytes and adipose tissue. Cys-39, which is involved in cross-linking of adiponectin monomers to form trimers, was identified as a key site of succination of adiponectin in adipocytes. 2SC was detected on two of seven monomeric forms of adiponectin immunoprecipitated from adipocytes and epididymal adipose tissue. Based on densitometry, 2SC-adiponectin accounted for ϳ7 and 8% of total intracellular adiponectin in cells and tissue, respectively. 2SC was found only in the intracellular, monomeric forms of adiponectin and was not detectable in polymeric forms of adiponectin in cell culture medium or plasma. We conclude that succination of adiponectin blocks its incorporation into trimeric and higher molecular weight, secreted forms of adiponectin. We propose that succination of proteins is a biomarker of mitochondrial stress and accumulation of Krebs cycle intermediates in adipose tissue in diabetes and that succination of adiponectin may contribute to the decrease in plasma adiponectin in diabetes.The accumulation of sugar and lipid-derived chemical modifications on proteins is associated with the etiology of several age-related diseases, including diabetes and its complications (1, 2). The irreversible adducts formed, termed advanced glycation/lipoxidation end products (AGE/ALEs), 2 accumulate over time on long lived proteins, such as collagens, affecting the solubility, elasticity, and proteolytic digestibility of the protein (3). AGE/ALEs are considered important mediators of the pathogenesis of diabetic complications through engagement of scavenger receptors, such as RAGE (receptor for AGE) and activation of proinflammatory signaling pathways (4). To date, the study of AGE/ALEs has focused mainly on modification of lysine and arginine residues in proteins by reactive carbonyl intermediates formed during metabolism or autoxidation of carbohydrates and lipids (2, 5). However, free cysteine is more abundant on intracellular proteins and, because of its greater nucleophilicity, is a more likely target for chemical modification by intracellular electrophiles.We recently identified S-(2-succinyl)-cysteine (2SC), a cysteine modification formed by a Michael addition reaction between the Krebs cycle intermediate fumarate and free sulfhydryl groups on proteins (6). This reaction, in which a thioether bond is formed, is described as succination of protein in order to distinguish it from succinylation, which leads to formation of amide, ester, or thioester bonds. 2SC was detected in human serum albumin and skin collagen and was increased in skeletal muscle protein and urine of diabetic rats. We also identified glyceraldehyde-3-phosphate dehydrogenase as one protein that is significantly modified by 2SC in skeletal muscle, resulting in the decrease in specific activity of glyceraldehyde-3-phosphate dehydr...
Purulent pericarditis is a rare disease in the era of antibiotics, with Streptococcus pyogenes being a possible, though uncommon etiology. Even more uncommon are mycotic aneurysms secondary to group A strep purulent pericarditis and bacteremia. We report a case of an 18-year-old female with a history of strep pharyngitis develop Streptococcus pyogenes purulent pericarditis with subsequent ventricular fibrillation (VF). Following initial stabilization, she ultimately developed a 4.8 cm mycotic aneurysm of the ascending aorta, with resultant compression of the pulmonary trunk and right pulmonary arteries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.