Identification of Regulatory Phosphorylation Sites in a Cell Volume– and Ste20 Kinase–dependent ClC Anion Channel

Changes in phosphorylation regulate the activity of various ClC anion transport proteins. However, the physiological context under which such regulation occurs and the signaling cascades that mediate phosphorylation are poorly understood. We have exploited the genetic model organism Caenorhabditis elegans to characterize ClC regulatory mechanisms and signaling networks. CLH-3b is a ClC anion channel that is expressed in the worm oocyte and excretory cell. Channel activation occurs in response to oocyte meiotic maturation and swelling via serine/threonine dephosphorylation mediated by the type I phosphatases GLC-7α and GLC-7β. A Ste20 kinase, germinal center kinase (GCK)-3, binds to the cytoplasmic C terminus of CLH-3b and inhibits channel activity in a phosphorylation-dependent manner. Analysis of hyperpolarization-induced activation kinetics suggests that phosphorylation may inhibit the ClC fast gating mechanism. GCK-3 is an ortholog of mammalian SPAK and OSR1, kinases that bind to, phosphorylate, and regulate the cell volume–dependent activity of mammalian cation-Cl− cotransporters. Using mass spectrometry and patch clamp electrophysiology, we demonstrate here that CLH-3b is a target of regulatory phosphorylation. Concomitant phosphorylation of S742 and S747, which are located 70 and 75 amino acids downstream from the GCK-3 binding site, are required for kinase-mediated channel inhibition. In contrast, swelling-induced channel activation occurs with dephosphorylation of S747 alone. Replacement of both S742 and S747 with glutamate gives rise to kinase- and swelling-insensitive channels that exhibit activity and biophysical properties similar to those of wild-type CLH-3b inhibited by GCK-3. Our studies provide novel insights into ClC regulation and mechanisms of cell volume signaling, and provide the foundation for studies aimed at defining how conformational changes in the cytoplasmic C terminus alter ClC gating and function in response to intracellular signaling events

A New LC-MS/MS Method for the Quantification of Endogenous and Vinyl Chloride-Induced 7-(2-Oxoethyl)Guanine in Sprague–Dawley Rats

Vinyl chloride (VC) is an industrial chemical that is known to be carcinogenic to animals and humans. VC primarily induces hepatic angiosarcomas following high exposures (≥50 ppm). VC is also found in Superfund sites at ppb concentrations as a result of microbial metabolism of trichloroethylene and perchloroethylene. Here, we report a new sensitive LC-MS/MS method to analyze the major DNA adduct formed by VC, 7-(2-oxoethylguanine) (7-OEG). We used this method to analyze tissue DNA from both adult and weanling rats exposed to 1100 ppm [13C2]-VC for 5 days. After neutral thermal hydrolysis, 7-OEG was derivatized with O-t-butyl hydroxylamine to an oxime adduct, followed by LC-MS/MS analysis. The limit of detection was 1 fmol and the limit of quantitation was 1.5 fmol on the column. The use of stable isotope VC allowed us to demonstrate for the first time that endogenous 7-OEG was present in tissue DNA. We hypothesized that endogenous 7-OEG was formed from lipid peroxidation and demonstrated the formation of [13C2]-7-OEG from the reaction of calf thymus DNA with [13C18]-ethyl linoleate (EtLa) under peroxidizing conditions. The concentrations of endogenous 7-OEG in liver, lung, kidney, spleen, testis and brain DNA from adult and weanling rats typically ranged from 1.0-10.0 adducts per 106 guanine. The exogenous 7-OEG in liver DNA from adult rats exposed to 1100 ppm [13C2]-VC for 5 days was 104.0 ± 23.0 adducts per 106 guanine (n=4), while concentrations in other tissues ranged from 1.0-39.0 adducts per 106 guanine (n=4). Although endogenous concentrations of 7-OEG in tissues in weanling rats were similar to those of adult rats, exogenous [13C2]-7-OEG concentrations were higher in weanlings, averaging 300 adducts per 106 guanine in liver. Studies on the persistence of [13C2]-7-OEG in adult rats sacrificed 2, 4, and 8 wks post exposure to [13C2]-VC demonstrated a half-life of 7-OEG of 4 days in both liver and lung

A Dynamic Pathway for Calcium-Independent Activation of CaMKII by Methionine Oxidation

SummaryCalcium/calmodulin (Ca2+/CaM)-dependent protein kinase II (CaMKII) couples increases in cellular Ca2+ to fundamental responses in excitable cells. CaMKII was identified over 20 years ago by activation dependence on Ca2+/CaM, but recent evidence shows that CaMKII activity is also enhanced by pro-oxidant conditions. Here we show that oxidation of paired regulatory domain methionine residues sustains CaMKII activity in the absence of Ca2+/CaM. CaMKII is activated by angiotensin II (AngII)-induced oxidation, leading to apoptosis in cardiomyocytes both in vitro and in vivo. CaMKII oxidation is reversed by methionine sulfoxide reductase A (MsrA), and MsrA−/− mice show exaggerated CaMKII oxidation and myocardial apoptosis, impaired cardiac function, and increased mortality after myocardial infarction. Our data demonstrate a dynamic mechanism for CaMKII activation by oxidation and highlight the critical importance of oxidation-dependent CaMKII activation to AngII and ischemic myocardial apoptosis

Allopurinol versus usual care in UK patients with ischaemic heart disease (ALL-HEART) : a multicentre, prospective, randomised, open-label, blinded-endpoint trial

Funding Information: ISM reports research grants from Menarini, EMA, Sanofi, Health Data Research UK, the British Heart Foundation, and Innovative Medicines Initiative; institutional consultancy income from AstraZeneca outside the submitted work; and personal income from AstraZeneca and Amgen outside the submitted work. TMM reports grants from Menarini/Ipsen/Teijin and Merck Sharp & Dohme outside the submitted work, and personal income for consultancy from Novartis and AstraZeneca outside the submitted work, and is a trustee of the Scottish Heart Arterial Risk Prevention Society. AGB reports personal income from Novartis, Mylan, AstraZeneca, Bayer, Daiichi-Sankyo, Boehringer, Pfizer, Galderma, Zambon, and Novo-Nordisk outside the submitted work. ADS and the University of Dundee hold a European patent for the use of xanthine oxidase inhibitors in treating chest pain in angina pectoris. AW declares personal income for consultancy from AbbVie, Akcea, Albireo, Alexion, Allergan, Amarin, Apsara, Arena, Astellas, AstraZeneca, Autolus, Bayer, Biocryst, Biogen, Biomarin, Bristol Myers Squibb, Boehringer Ingelheim, Calico, Celgene, Chiesi, Daiichi Sankyo, Diurnal, Elsai, Eli Lilly, Ferring, Galapagos, Gedeon Richter, Gilead, GlaxoSmithKline, GW Pharma, Idorsia, Incyte, Intercept, Ionis, Ipsen, Janssen, Jazz, Jcyte, Kite Gilead, LEK, Leo Pharma, Les Laboratoires Servier, Lundbeck, Merck (Merck Sharp & Dohme), Merck-Serono, Mitenyi, Mundibiopharma, Mustang Bio, Mylan, Myovant, Norgine, Novartis, Novo Nordisk, Orchard, Paion, Pfizer, Pierre Fabre, PTC, RegenXBio, Rhythm, Sanofi, Santen, Sarepta, SeaGen, Shionogi, Sigmatec, SOBI, Takeda, Tanaya, UCB, and Vertex outside the submitted work. JST declares research funding from the UK National Institute for Health and Care Research (NIHR) and NHS England outside the submitted work and membership of a UK National Institute for Health and Care Excellence guideline committee on management of atrial fibrillation. All other authors declare no competing interests. Funding Information: This study was funded by the NIHR Health Technology Assessment programme (HTA 11/36/41 to ISM, IF, CJH, LW, ADS, AGB, AJA, AW, JST, and TMM). The views expressed are those of the authors and not necessarily those of the NIHR or the UK Department of Health and Social Care. The study was supported by the Scottish Primary Care Research Network, Support for Science Scotland (Grampian, Highlands, Tayside, Fife, Forth Valley, Greater Glasgow and Clyde, Lothian, Ayrshire and Arran, Dumfries and Galloway, and Lanarkshire), and the NIHR Local Clinical Research Networks (East Midlands, West Midlands, Eastern, North Thames, Yorkshire and Humber, North East and North Cumbria, North West Coast, Kent, Surrey and Sussex, and South West Peninsula), which assisted with recruitment and other study activities. We thank Public Health Scotland and NHS Digital for providing data linkage. We thank all the participants, physicians, nurses, and other staff who participated in the ALL-HEART study. Funding Information: This study was funded by the NIHR Health Technology Assessment programme (HTA 11/36/41 to ISM, IF, CJH, LW, ADS, AGB, AJA, AW, JST, and TMM). The views expressed are those of the authors and not necessarily those of the NIHR or the UK Department of Health and Social Care. The study was supported by the Scottish Primary Care Research Network, Support for Science Scotland (Grampian, Highlands, Tayside, Fife, Forth Valley, Greater Glasgow and Clyde, Lothian, Ayrshire and Arran, Dumfries and Galloway, and Lanarkshire), and the NIHR Local Clinical Research Networks (East Midlands, West Midlands, Eastern, North Thames, Yorkshire and Humber, North East and North Cumbria, North West Coast, Kent, Surrey and Sussex, and South West Peninsula), which assisted with recruitment and other study activities. We thank Public Health Scotland and NHS Digital for providing data linkage. We thank all the participants, physicians, nurses, and other staff who participated in the ALL-HEART study. Publisher Copyright: © 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licensePeer reviewedPublisher PD

Allopurinol versus usual care in UK patients with ischaemic heart disease (ALL-HEART): a multicentre, prospective, randomised, open-label, blinded-endpoint trial

BACKGROUND: Allopurinol is a urate-lowering therapy used to treat patients with gout. Previous studies have shown that allopurinol has positive effects on several cardiovascular parameters. The ALL-HEART study aimed to determine whether allopurinol therapy improves major cardiovascular outcomes in patients with ischaemic heart disease. METHODS: ALL-HEART was a multicentre, prospective, randomised, open-label, blinded-endpoint trial done in 18 regional centres in England and Scotland, with patients recruited from 424 primary care practices. Eligible patients were aged 60 years or older, with ischaemic heart disease but no history of gout. Participants were randomly assigned (1:1), using a central web-based randomisation system accessed via a web-based application or an interactive voice response system, to receive oral allopurinol up-titrated to a dose of 600 mg daily (300 mg daily in participants with moderate renal impairment at baseline) or to continue usual care. The primary outcome was the composite cardiovascular endpoint of non-fatal myocardial infarction, non-fatal stroke, or cardiovascular death. The hazard ratio (allopurinol vs usual care) in a Cox proportional hazards model was assessed for superiority in a modified intention-to-treat analysis (excluding randomly assigned patients later found to have met one of the exclusion criteria). The safety analysis population included all patients in the modified intention-to-treat usual care group and those who took at least one dose of randomised medication in the allopurinol group. This study is registered with the EU Clinical Trials Register, EudraCT 2013-003559-39, and ISRCTN, ISRCTN32017426. FINDINGS: Between Feb 7, 2014, and Oct 2, 2017, 5937 participants were enrolled and then randomly assigned to receive allopurinol or usual care. After exclusion of 216 patients after randomisation, 5721 participants (mean age 72·0 years [SD 6·8], 4321 [75·5%] males, and 5676 [99·2%] white) were included in the modified intention-to-treat population, with 2853 in the allopurinol group and 2868 in the usual care group. Mean follow-up time in the study was 4·8 years (1·5). There was no evidence of a difference between the randomised treatment groups in the rates of the primary endpoint. 314 (11·0%) participants in the allopurinol group (2·47 events per 100 patient-years) and 325 (11·3%) in the usual care group (2·37 events per 100 patient-years) had a primary endpoint (hazard ratio [HR] 1·04 [95% CI 0·89–1·21], p=0·65). 288 (10·1%) participants in the allopurinol group and 303 (10·6%) participants in the usual care group died from any cause (HR 1·02 [95% CI 0·87–1·20], p=0·77). INTERPRETATION: In this large, randomised clinical trial in patients aged 60 years or older with ischaemic heart disease but no history of gout, there was no difference in the primary outcome of non-fatal myocardial infarction, non-fatal stroke, or cardiovascular death between participants randomised to allopurinol therapy and those randomised to usual care. FUNDING: UK National Institute for Health and Care Research

Multi-site assessment of the precision and reproducibility of multiple reaction monitoring–based measurements of proteins in plasma

Verification of candidate biomarkers relies upon specific, quantitative assays optimized for selective detection of target proteins, and is increasingly viewed as a critical step in the discovery pipeline that bridges unbiased biomarker discovery to preclinical validation. Although individual laboratories have demonstrated that multiple reaction monitoring (MRM) coupled with isotope dilution mass spectrometry can quantify candidate protein biomarkers in plasma, reproducibility and transferability of these assays between laboratories have not been demonstrated. We describe a multilaboratory study to assess reproducibility, recovery, linear dynamic range and limits of detection and quantification of multiplexed, MRM-based assays, conducted by NCI-CPTAC. Using common materials and standardized protocols, we demonstrate that these assays can be highly reproducible within and across laboratories and instrument platforms, and are sensitive to low µg/ml protein concentrations in unfractionated plasma. We provide data and benchmarks against which individual laboratories can compare their performance and evaluate new technologies for biomarker verification in plasma