Phorbol esters increase the amount of Ca2+, phospholipid-dependent protein kinase associated with plasma membrane

Although the biochemical mechanism of action of phorbol ester tumour promoters is not fully understood, it is known that phorbol ester binding to the cell surface causes rapid changes in calcium flux and phospholipid metabolism. A protein kinase activity has recently been described which is dependent on calcium and acidic phospholipids and is further enhanced by diacylglycerol. Previously, we have observed that phorbol ester treatment of EL4 mouse thymoma cells causes a rapid decrease in cytosolic calcium, phospholipid-dependent protein kinase (Ca, PL-PK) activity, which is mediated through the specific phorbol ester cell-surface receptors identified on EL4 cells. We now show that treatment of parietal yolk sacs (PYS-2) cells with biologically active 12-O-tetradecanoyl phorbol-13-acetate (TPA) provokes a rapid decrease in cytosolic Ca, PL-PK activity that is accompanied by a significant increase in the amount of Ca, PL-PK activity associated with the plasma membrane fraction. These results suggest that the rapid and tight association of Ca, PL-PK activity with the plasma membrane may be an early event in mediating some of the effects of phorbol esters.

A genome-wide association study in chronic obstructive pulmonary disease (COPD): identification of two major susceptibility loci

There is considerable variability in the susceptibility of smokers to develop chronic obstructive pulmonary disease (COPD). The only known genetic risk factor is severe deficiency of alpha(1)-antitrypsin, which is present in 1-2% of individuals with COPD. We conducted a genome-wide association study (GWAS) in a homogenous case-control cohort from Bergen, Norway (823 COPD cases and 810 smoking controls) and evaluated the top 100 single nucleotide polymorphisms (SNPs) in the family-based International COPD Genetics Network (ICGN; 1891 Caucasian individuals from 606 pedigrees) study. The polymorphisms that showed replication were further evaluated in 389 subjects from the US National Emphysema Treatment Trial (NETT) and 472 controls from the Normative Aging Study (NAS) and then in a fourth cohort of 949 individuals from 127 extended pedigrees from the Boston Early-Onset COPD population. Logistic regression models with adjustments of covariates were used to analyze the case-control populations. Family-based association analyses were conducted for a diagnosis of COPD and lung function in the family populations. Two SNPs at the alpha-nicotinic acetylcholine receptor (CHRNA 3/5) locus were identified in the genome-wide association study. They showed unambiguous replication in the ICGN family-based analysis and in the NETT case-control analysis with combined p-values of 1.48 x 10(-10), (rs8034191) and 5.74 x 10(-10) (rs1051730). Furthermore, these SNPs were significantly associated with lung function in both the ICGN and Boston Early-Onset COPD populations. The C allele of the rs8034191 SNP was estimated to have a population attributable risk for COPD of 12.2%. The association of hedgehog interacting protein (HHIP) locus on chromosome 4 was also consistently replicated, but did not reach genome-wide significance levels. Genome-wide significant association of the HHIP locus with lung function was identified in the Framingham Heart study (Wilk et al., companion article in this issue of PLoS Genetics; doi:10.1371/journal.pgen.1000429). The CHRNA 3/5 and the HHIP loci make a significant contribution to the risk of COPD. CHRNA3/5 is the same locus that has been implicated in the risk of lung cancer.

Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE)

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease and not well understood. The forced expiratory volume in one second is used for the diagnosis and staging of COPD, but there is wide acceptance that it is a crude measure and insensitive to change over shorter periods of time. Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE) is a 3-yr longitudinal study with four specific aims: 1) definition of clinically relevant COPD subtypes; 2) identification of parameters that predict disease progression in these subtypes; 3) examination of biomarkers that correlate with COPD subtypes and may predict disease progression; and 4) identification of novel genetic factors and/or biomarkers that both correlate with clinically relevant COPD subtypes and predict disease progression. ECLIPSE plans to recruit 2,180 COPD subjects in Global Initiative for Chronic Obstructive Lung Disease categories II-IV and 343 smoking and 223 nonsmoking control subjects. Study procedures are to be performed at baseline, 3 months, 6 months and every 6 months thereafter. Assessments include pulmonary function measurements (spirometry, impulse oscillometry and plethysmography), chest computed tomography, biomarker measurement (in blood, sputum, urine and exhaled breath condensate), health outcomes, body impedance, resting oxygen saturation and 6-min walking distance. Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points is the largest study attempting to better describe the subtypes of chronic obstructive pulmonary disease, as well as defining predictive markers of its progression.

Interleukin-2 stimulates association of protein kinase C with plasma membrane

Interleukin-2 (IL-2) is a regulatory peptide important for the growth and differentiation of antigen-specific T lymphocytes and large granular lymphocytes. Interaction of IL-2 with its specific receptor results in the promotion of S-phase progression as well as, in certain circumstances, the production and release of gamma-interferon (IFN-gamma). Although the binding of IL-2 with high-affinity specific receptors has been well characterized, the intracellular mechanisms by which this ligand-receptor interaction promotes growth and differentiation are unknown. Here, we present evidence that IL-2/receptor interaction produces a rapid and transient redistribution of protein kinase C (PK-C) from the cytosol to the plasma membrane. Phorbol myristate acetate (PMA) also induces PK-C transposition in an analogous manner, except that PMA-induced PK-C transposition to the plasma membrane is apparently protracted. As phorbol esters have been shown to mimic IL-2 in the regulation of cellular proliferation as well as IFN-gamma production, the activation of PK-C by either phorbol esters or IL-2/receptor interaction seems to have a crucial role in signal transduction elicited by these extracellular messengers.

Ca2+- and phospholipid-independent activation of protein kinase C by selective oxidative modification of the regulatory domain

The susceptibility of purified protein kinase C to oxidative inactivation by H2O2 was found to be increased by Ca2+ either alone at a high (5 mM) concentration or at a low (approximately 50 microM) concentration along with phosphatidylserine and diacylglycerol and by tumor-promoting phorbol esters even in the absence of Ca2+. This suggested that the membrane-bound and/or catalytically active form of protein kinase C is relatively more susceptible to oxidative inactivation. Although both the regulatory and catalytic domains of protein kinase C were susceptible to oxidative inactivation, a selective modification of the regulatory domain was obtained under mild oxidative conditions by protecting the catalytic site with ATP/Mg2+. Under these conditions there was a loss of both phorbol ester binding and Ca2+/phospholipid-stimulated kinase activity. However, this modified form of enzyme exhibited an increase in Ca2+/phospholipid-independent kinase activity. This suggests that selective oxidative modification of the regulatory domain may negate the requirement for Ca2+ and lipids for activation. Treatment of intact C6 glioma or B16 melanoma cells with H2O2 resulted in a time- and temperature-dependent decrease in Ca2+/phospholipid-dependent protein kinase C activity along with a concomitant transient increase in an oxidatively modified isoform of protein kinase C that exhibited activity in the absence of Ca2+ and phospholipids. Since protein kinase C can initially be activated by mild oxidative modification and subsequently inactivated by further oxidation, this dual activation-inactivation of protein kinase C in response to H2O2 suggests an effective on/off signal mechanism to influence cellular events.

Discovery of the dual orexin receptor antagonist [(7R)-4-(5-chloro-1,3-benzoxazol-2-yl)-7-methyl-1,4-diazepan-1-yl][5-methyl-2-(2H-1,2,3-triazol-2-yl)phenyl]methanone (MK-4305) for the treatment of insomnia

Despite increased understanding of the biological basis for sleep control in the brain, few novel mechanisms for the treatment of insomnia have been identified in recent years. One notable exception is inhibition of the excitatory neuropeptides orexins A and B by design of orexin receptor antagonists. Herein, we describe how efforts to understand the origin of poor oral pharmacokinetics in a leading HTS-derived diazepane orexin receptor antagonist led to the identification of compound 10 with a 7-methyl substitution on the diazepane core. Though 10 displayed good potency, improved pharmacokinetics, and excellent in vivo efficacy, it formed reactive metabolites in microsomal incubations. A mechanistic hypothesis coupled with an in vitro assay to assess bioactivation led to replacement of the fluoroquinazoline ring of 10 with a chlorobenzoxazole to provide 3 (MK-4305), a potent dual orexin receptor antagonist that is currently being tested in phase III clinical trials for the treatment of primary insomnia.

Metabolic features of chronic fatigue syndrome

More than 2 million people in the United States have myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). We performed targeted, broad-spectrum metabolomics to gain insights into the biology of CFS. We studied a total of 84 subjects using these methods. Forty-five subjects (n = 22 men and 23 women) met diagnostic criteria for ME/CFS by Institute of Medicine, Canadian, and Fukuda criteria. Thirty-nine subjects (n = 18 men and 21 women) were age- and sex-matched normal controls. Males with CFS were 53 (±2.8) y old (mean ± SEM; range, 21-67 y). Females were 52 (±2.5) y old (range, 20-67 y). The Karnofsky performance scores were 62 (±3.2) for males and 54 (±3.3) for females. We targeted 612 metabolites in plasma from 63 biochemical pathways by hydrophilic interaction liquid chromatography, electrospray ionization, and tandem mass spectrometry in a single-injection method. Patients with CFS showed abnormalities in 20 metabolic pathways. Eighty percent of the diagnostic metabolites were decreased, consistent with a hypometabolic syndrome. Pathway abnormalities included sphingolipid, phospholipid, purine, cholesterol, microbiome, pyrroline-5-carboxylate, riboflavin, branch chain amino acid, peroxisomal, and mitochondrial metabolism. Area under the receiver operator characteristic curve analysis showed diagnostic accuracies of 94% [95% confidence interval (CI), 84-100%] in males using eight metabolites and 96% (95% CI, 86-100%) in females using 13 metabolites. Our data show that despite the heterogeneity of factors leading to CFS, the cellular metabolic response in patients was homogeneous, statistically robust, and chemically similar to the evolutionarily conserved persistence response to environmental stress known as dauer.

Cigarette smoking behaviors and time since quitting are associated with differential DNA methylation across the human genome

The impact of cigarette smoking can persist for extended periods following smoking cessation and may involve epigenetic reprogramming. Changes in DNA methylation associated with smoking may help to identify molecular pathways that contribute to the latency between exposure and disease onset. Cross-sectional cohort data from subjects in the International COPD Genetics Network (n = 1085) and the Boston Early-Onset COPD study (n = 369) were analyzed as the discovery and replication cohorts, respectively. Genome-wide methylation data on 27 578 CpG sites in 14 475 genes were obtained on DNA from peripheral blood leukocytes using the Illumina HumanMethylation27K Beadchip in both cohorts. We identified 15 sites significantly associated with current smoking, 2 sites associated with cumulative smoke exposure, and, within the subset of former smokers, 3 sites associated with time since quitting cigarettes. Two loci, factor II receptor-like 3 (F2RL3) and G-protein-coupled receptor 15 (GPR15), were significantly associated in all three analyses and were validated by pyrosequencing. These findings (i) identify a novel locus (GPR15) associated with cigarette smoking and (ii) suggest the existence of dynamic, site-specific methylation changes in response to smoking which may contribute to the extended risks associated with cigarette smoking that persist after cessation.

Altered cytosol/membrane enzyme redistribution on interleukin-3 activation of protein kinase C

Interleukin-3 (IL-3) is a member of a family of growth and differentiation peptides, collectively referred to as colony-stimulating factors, which regulate haematopoiesis. IL-3 has been highly purified from medium conditioned by WEHI-3B cells, and recently the molecular cloning of complementary DNA for murine IL-3 has been reported. IL-3 seems to stimulate a wide range of colony-forming cells derived from murine bone marrow and has consequently been studied under a variety of names, including burst-promoting activity, mast cell growth factor, P-cell stimulating factor and multi-colony-stimulating factor. Here we present evidence that IL-3-receptor interaction stimulates the rapid and transient redistribution of protein kinase C (PK-C) from cytosol to plasma membrane in FDC-P1 cells. Phorbol myristate acetate (PMA) is shown to have a similar effect in these IL-3-dependent FDC-P1 cells. Our data suggest that IL-3 and phorbol esters share a common feature of transmembrane signalling crucial for growth and differentiation.

Use of a long-acting inhaled beta2-adrenergic agonist, salmeterol xinafoate, in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a condition in which continuous bronchodilation may have clinical advantages. This study evaluated salmeterol, a beta-agonist bronchodilator with a duration of action substantially longer than that of short-acting beta-agonists, compared with ipratropium, an anticholinergic bronchodilator, and placebo in patients with COPD. Four hundred and five patients with COPD received either salmeterol 42 microg twice daily, ipratropium bromide 36 microg four times daily, or placebo for 12 wk in this randomized, double-blind, parallel-group study. Patients were stratified on the basis of bronchodilator response to albuterol (> 12% and > 200-ml improvement) and were randomized within each stratum. Bronchodilator response was measured over 12 h four times during the treatment period. Salmeterol provided similar maximal bronchodilatation to ipratropium but had a longer duration of action and a more constant bronchodilatory effect with no evidence of bronchodilator tolerance. Both active treatments were well tolerated. Salmeterol was an effective bronchodilator with a consistent effect over this 12-wk study in patients with COPD, including those "unresponsive" to albuterol. The long duration of action of salmeterol offers the advantage of twice daily dosing compared with the required four times a day dosing with ipratropium.

Variable DNA methylation is associated with chronic obstructive pulmonary disease and lung function

RATIONALE

Chronic obstructive pulmonary disease (COPD) is associated with local (lung) and systemic (blood) inflammation and manifestations. DNA methylation is an important regulator of gene transcription, and global and specific gene methylation marks may vary with cigarette smoke exposure.

OBJECTIVES

To perform a comprehensive assessment of methylation marks in DNA from subjects well phenotyped for nonneoplastic lung disease.

METHODS

We conducted array-based methylation screens, using a test-replication approach, in two family-based cohorts (n = 1,085 and 369 subjects).

MEASUREMENTS AND MAIN RESULTS

We observed 349 CpG sites significantly associated with the presence and severity of COPD in both cohorts. Seventy percent of the associated CpG sites were outside of CpG islands, with the majority of CpG sites relatively hypomethylated. Gene ontology analysis based on these 349 CpGs (330 genes) suggested the involvement of a number of genes responsible for immune and inflammatory system pathways, responses to stress and external stimuli, as well as wound healing and coagulation cascades. Interestingly, our observations include significant, replicable associations between SERPINA1 hypomethylation and COPD and lower average lung function phenotypes (combined P values: COPD, 1.5 × 10(-23); FEV(1)/FVC, 1.5 × 10(-35); FEV(1), 2.2 × 10(-40)).

CONCLUSIONS

Genetic and epigenetic pathways may both contribute to COPD. Many of the top associations between COPD and DNA methylation occur in biologically plausible pathways. This large-scale analysis suggests that DNA methylation may be a biomarker of COPD and may highlight new pathways of COPD pathogenesis.

Protein kinase C epsilon is localized to the Golgi via its zinc-finger domain and modulates Golgi function

Protein kinase C (PKC) is a multigene family of serine/threonine kinases that are central to many signal transduction pathways. Among the PKC isozymes, only PKC epsilon has been reported to exhibit full oncogenic potential. PKC epsilon also displays unique substrate specificity and intracellular localization. To examine the interrelationship between the biological effects and domain structure of PKC epsilon, NIH 3T3 cells were stably transfected to overexpress different epitope-tagged fragments of PKC epsilon. The overexpressed proteins each contain the epsilon-tag peptide at the C terminus to allow ready detection with an antibody specific for the tag. The holo-PKC epsilon was found to localize with the Golgi network and other compartments, whereas the zinc-finger domain localized exclusively at the Golgi. Golgi-specific glycosaminoglycan sulfation was strongly inhibited in cells overexpressing either holo-PKC epsilon or its zinc-finger domain, while the secretion of sulfated glycosaminoglycans into the medium was impaired in cells expressing the PKC epsilon zinc-finger domain. Thus, these results suggest that PKC epsilon may be involved in specifically regulating Golgi-related processes. Further, the results indicate that PKC epsilon domains other than the kinase domain may also have biological activity and that the zinc-finger domain may function as a subcellular localization signal.

Thyroid hormone insufficiency during brain development reduces parvalbumin immunoreactivity and inhibitory function in the hippocampus

Thyroid hormones are necessary for brain development. gamma-Amino-butyric acid (GABA)ergic interneurons comprise the bulk of local inhibitory circuitry in brain, many of which contain the calcium binding protein, parvalbumin (PV). A previous report indicated that severe postnatal hypothyroidism reduces PV immunoreactivity (IR) in rat neocortex. We examined PV-IR and GABA-mediated synaptic inhibition in the hippocampus of rats deprived of thyroid hormone from gestational d 6 until weaning on postnatal d 30. Pregnant dams were exposed to propylthiouracil (0, 3, 10 ppm) via the drinking water, which decreased maternal serum T(4) by approximately 50-75% and increased TSH. At weaning, T(4) was reduced by approximately 70% in offspring in the low-dose group and fell below detectable levels in high-dose animals. PV-IR was diminished in the hippocampus and neocortex of offspring killed on postnatal d 21, an effect that could be reversed by postnatal administration of T(4). Dose-dependent decreases in the density of PV-IR neurons were observed in neocortex and hippocampus, with the dentate gyrus showing the most severe reductions (50-75% below control counts). Altered staining persisted to adulthood despite the return of thyroid hormones to control levels. Developmental cross-fostering and adult-onset deprivation studies revealed that early postnatal hormone insufficiency was required for an alteration in PV-IR. Synaptic inhibition of the perforant path-dentate gyrus synapse evaluated in adult offspring, in vivo, revealed dose-dependent reductions in paired pulse depression indicative of a suppression of GABA-mediated inhibition. These data demonstrate that moderate degrees of thyroid hormone insufficiency during the early postnatal period permanently alters interneuron expression of PV and compromises inhibitory function in the hippocampus.

Mucus Plugs and Emphysema in the Pathophysiology of Airflow Obstruction and Hypoxemia in Smokers

Rationale: The relative roles of mucus plugs and emphysema in mechanisms of airflow limitation and hypoxemia in smokers with chronic obstructive pulmonary disease (COPD) are uncertain.Objectives: To relate image-based measures of mucus plugs and emphysema to measures of airflow obstruction and oxygenation in patients with COPD.Methods: We analyzed computed tomographic (CT) lung images and lung function in participants in the Subpopulations and Intermediate Outcome Measures in COPD Study. Radiologists scored mucus plugs on CT lung images, and imaging software automatically quantified emphysema percentage. Unadjusted and adjusted relationships between mucus plug score, emphysema percentage, and lung function were determined using regression.Measurements and Main Results: Among 400 smokers, 229 (57%) had mucus plugs and 207 (52%) had emphysema, and subgroups could be identified with mucus-dominant and emphysema-dominant disease. Only 33% of smokers with high mucus plug scores had mucus symptoms. Mucus plug score and emphysema percentage were independently associated with lower values for FEV1 and peripheral oxygen saturation (P < 0.001). The relationships between mucus plug score and lung function outcomes were strongest in smokers with limited emphysema (P < 0.001). Compared with smokers with low mucus plug scores, those with high scores had worse COPD Assessment Test scores (17.4 ± 7.7 vs. 14.4 ± 13.3), more frequent annual exacerbations (0.75 ± 1.1 vs. 0.43 ± 0.85), and shorter 6-minute-walk distance (329 ± 115 vs. 392 ± 117 m) (P < 0.001).Conclusions: Symptomatically silent mucus plugs are highly prevalent in smokers and independently associate with lung function outcomes. These data provide rationale for targeting patients with mucus-high/emphysema-low COPD in clinical trials of mucoactive treatments.Clinical trial registered with www.clinicaltrials.gov (NCT01969344).