Semi-automated image analysis: detecting carbonylation in subcellular regions of skeletal muscle

Measurement of Reactive Oxygen Species, Reactive Nitrogen Species, and Redox-Dependent Signaling in the Cardiovascular System: A Scientific Statement From the American Heart Association

Reactive oxygen species and reactive nitrogen species are biological molecules that play important roles in cardiovascular physiology and contribute to disease initiation, progression, and severity. Because of their ephemeral nature and rapid reactivity, these species are difficult to measure directly with high accuracy and precision. In this statement, we review current methods for measuring these species and the secondary products they generate and suggest approaches for measuring redox status, oxidative stress, and the production of individual reactive oxygen and nitrogen species. We discuss the strengths and limitations of different methods and the relative specificity and suitability of these methods for measuring the concentrations of reactive oxygen and reactive nitrogen species in cells, tissues, and biological fluids. We provide specific guidelines, through expert opinion, for choosing reliable and reproducible assays for different experimental and clinical situations. These guidelines are intended to help investigators and clinical researchers avoid experimental error and ensure high-quality measurements of these important biological species.

Fluorescence labeling of carbonylated lipids and proteins in cells using coumarin-hydrazide

Carbonylation is a generic term which refers to reactive carbonyl groups present in biomolecules due to oxidative reactions induced by reactive oxygen species. Carbonylated proteins, lipids and nucleic acids have been intensively studied and often associated with onset or progression of oxidative stress related disorders. In order to reveal underlying carbonylation pathways and biological relevance, it is crucial to study their intracellular formation and spatial distribution. Carbonylated species are usually identified and quantified in cell lysates and body fluids after derivatization using specific chemical probes. However, spatial cellular and tissue distribution have been less often investigated. Here, we report coumarin-hydrazide, a fluorescent chemical probe for time- and cost-efficient labeling of cellular carbonyls followed by fluorescence microscopy to evaluate their intracellular formation both in time and space. The specificity of coumarin-hydrazide was confirmed in time- and dose-dependent experiments using human primary fibroblasts stressed with paraquat and compared with conventional DNPH-based immunocytochemistry. Both techniques stained carbonylated species accumulated in cytoplasm with strong perinuclear clustering. Using a complimentary array of analytical methods specificity of coumarin-hydrazide probe towards both protein- and lipid-bound carbonyls has been shown. Additionally, co-distribution of carbonylated species and oxidized phospholipids was demonstrated.

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Coumarin-hydrazide (CHH) chemical probe was used to label cellular carbonyls.

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CHH fluorescence microscopy allowed to monitor protein and lipid carbonyl distribution.

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CHH specificity towards protein- and lipid-bound carbonyls was demonstrated.

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CHH labeling and DNPH immunocytochemistry for microscopy imaging were compared.

Re-evaluation of the role of calcium homeostasis endoplasmic reticulum protein (CHERP) in cellular calcium signaling

Changes in cytoplasmic Ca(2+) concentration, resulting from activation of intracellular Ca(2+) channels within the endoplasmic reticulum, regulate several aspects of cellular growth and differentiation. Ca(2+) homeostasis endoplasmic reticulum protein (CHERP) is a ubiquitously expressed protein that has been proposed as a regulator of both major families of endoplasmic reticulum Ca(2+) channels, inositol 1,4,5-trisphosphate receptors (IP(3)Rs) and ryanodine receptors (RyRs), with resulting effects on mitotic cycling. However, the manner by which CHERP regulates intracellular Ca(2+) channels to impact cellular growth is unknown. Here, we challenge previous findings that CHERP acts as a direct cytoplasmic regulator of IP(3)Rs and RyRs and propose that CHERP acts in the nucleus to impact cellular proliferation by regulating the function of the U2 snRNA spliceosomal complex. The previously reported effects of CHERP on cellular growth therefore are likely indirect effects of altered spliceosomal function, consistent with prior data showing that loss of function of U2 snRNP components can interfere with cell growth and induce cell cycle arrest.