J Hunter Cox, Richard S McCain, Emery Tran, Shoba Swaminathan, Holland H Smith, Gerardo G Piroli, Michael Shtutman, Michael D Walla, William E Cotham, Norma Frizzell
{"title":"Quantification of the immunometabolite protein modifications S-2-succinocysteine and 2,3-dicarboxypropylcysteine.","authors":"J Hunter Cox, Richard S McCain, Emery Tran, Shoba Swaminathan, Holland H Smith, Gerardo G Piroli, Michael Shtutman, Michael D Walla, William E Cotham, Norma Frizzell","doi":"10.1152/ajpendo.00354.2023","DOIUrl":null,"url":null,"abstract":"<p><p>The tricarboxylic acid (TCA) cycle metabolite fumarate nonenzymatically reacts with the amino acid cysteine to form S-(2-succino)cysteine (2SC), referred to as protein succination. The immunometabolite itaconate accumulates during lipopolysaccharide (LPS) stimulation of macrophages and microglia. Itaconate nonenzymatically reacts with cysteine residues to generate 2,3-dicarboxypropylcysteine (2,3-DCP), referred to as protein dicarboxypropylation. Since fumarate and itaconate levels dynamically change in activated immune cells, the levels of both 2SC and 2,3-DCP reflect the abundance of these metabolites and their capacity to modify protein thiols. We generated ethyl esters of 2SC and 2,3-DCP from protein hydrolysates and used stable isotope dilution mass spectrometry to determine the abundance of these in LPS-stimulated Highly Aggressively Proliferating Immortalized (HAPI) microglia. To quantify the stoichiometry of the succination and dicarboxypropylation, reduced cysteines were alkylated with iodoacetic acid to form S-carboxymethylcysteine (CMC), which was then esterified. Itaconate-derived 2,3-DCP, but not fumarate-derived 2SC, increased in LPS-treated HAPI microglia. Stoichiometric measurements demonstrated that 2,3-DCP increased from 1.57% to 9.07% of total cysteines upon LPS stimulation. This methodology to simultaneously distinguish and quantify both 2SC and 2,3-DCP will have broad applications in the physiology of metabolic diseases. In addition, we find that available anti-2SC antibodies also detect the structurally similar 2,3-DCP, therefore \"succinate moiety\" may better describe the antigen recognized.<b>NEW & NOTEWORTHY</b> Itaconate and fumarate have roles as immunometabolites modulating the macrophage response to inflammation. Both immunometabolites chemically modify protein cysteine residues to modulate the immune response. Itaconate and fumarate levels change dynamically, whereas their stable protein modifications can be quantified by mass spectrometry. This method distinguishes itaconate and fumarate-derived protein modifications and will allow researchers to quantify their contributions in isolated cell types and tissues across a range of metabolic diseases.</p>","PeriodicalId":7594,"journal":{"name":"American journal of physiology. Endocrinology and metabolism","volume":null,"pages":null},"PeriodicalIF":4.2000,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"American journal of physiology. Endocrinology and metabolism","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1152/ajpendo.00354.2023","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/2/7 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"ENDOCRINOLOGY & METABOLISM","Score":null,"Total":0}
引用次数: 0
Abstract
The tricarboxylic acid (TCA) cycle metabolite fumarate nonenzymatically reacts with the amino acid cysteine to form S-(2-succino)cysteine (2SC), referred to as protein succination. The immunometabolite itaconate accumulates during lipopolysaccharide (LPS) stimulation of macrophages and microglia. Itaconate nonenzymatically reacts with cysteine residues to generate 2,3-dicarboxypropylcysteine (2,3-DCP), referred to as protein dicarboxypropylation. Since fumarate and itaconate levels dynamically change in activated immune cells, the levels of both 2SC and 2,3-DCP reflect the abundance of these metabolites and their capacity to modify protein thiols. We generated ethyl esters of 2SC and 2,3-DCP from protein hydrolysates and used stable isotope dilution mass spectrometry to determine the abundance of these in LPS-stimulated Highly Aggressively Proliferating Immortalized (HAPI) microglia. To quantify the stoichiometry of the succination and dicarboxypropylation, reduced cysteines were alkylated with iodoacetic acid to form S-carboxymethylcysteine (CMC), which was then esterified. Itaconate-derived 2,3-DCP, but not fumarate-derived 2SC, increased in LPS-treated HAPI microglia. Stoichiometric measurements demonstrated that 2,3-DCP increased from 1.57% to 9.07% of total cysteines upon LPS stimulation. This methodology to simultaneously distinguish and quantify both 2SC and 2,3-DCP will have broad applications in the physiology of metabolic diseases. In addition, we find that available anti-2SC antibodies also detect the structurally similar 2,3-DCP, therefore "succinate moiety" may better describe the antigen recognized.NEW & NOTEWORTHY Itaconate and fumarate have roles as immunometabolites modulating the macrophage response to inflammation. Both immunometabolites chemically modify protein cysteine residues to modulate the immune response. Itaconate and fumarate levels change dynamically, whereas their stable protein modifications can be quantified by mass spectrometry. This method distinguishes itaconate and fumarate-derived protein modifications and will allow researchers to quantify their contributions in isolated cell types and tissues across a range of metabolic diseases.
期刊介绍:
The American Journal of Physiology-Endocrinology and Metabolism publishes original, mechanistic studies on the physiology of endocrine and metabolic systems. Physiological, cellular, and molecular studies in whole animals or humans will be considered. Specific themes include, but are not limited to, mechanisms of hormone and growth factor action; hormonal and nutritional regulation of metabolism, inflammation, microbiome and energy balance; integrative organ cross talk; paracrine and autocrine control of endocrine cells; function and activation of hormone receptors; endocrine or metabolic control of channels, transporters, and membrane function; temporal analysis of hormone secretion and metabolism; and mathematical/kinetic modeling of metabolism. Novel molecular, immunological, or biophysical studies of hormone action are also welcome.