Vesicular and non-vesicular transport feed distinct glycosylation pathways in the Golgi.

Newly synthesized proteins and lipids are transported across the Golgi complex via different mechanisms whose respective roles are not completely clear. We previously identified a non-vesicular intra-Golgi transport pathway for glucosylceramide (GlcCer)--the common precursor of the different series of glycosphingolipids-that is operated by the cytosolic GlcCer-transfer protein FAPP2 (also known as PLEKHA8) (ref. 1). However, the molecular determinants of the FAPP2-mediated transfer of GlcCer from the cis-Golgi to the trans-Golgi network, as well as the physiological relevance of maintaining two parallel transport pathways of GlcCer--vesicular and non-vesicular--through the Golgi, remain poorly defined. Here, using mouse and cell models, we clarify the molecular mechanisms underlying the intra-Golgi vectorial transfer of GlcCer by FAPP2 and show that GlcCer is channelled by vesicular and non-vesicular transport to two topologically distinct glycosylation tracks in the Golgi cisternae and the trans-Golgi network, respectively. Our results indicate that the transport modality across the Golgi complex is a key determinant for the glycosylation pattern of a cargo and establish a new paradigm for the branching of the glycosphingolipid synthetic pathway.

Reactive Oxygen Species in COPD-Related Vascular Remodeling.

The pathogenesis of chronic obstructive pulmonary disease (COPD) is a multifaceted process involving the alteration of pulmonary vasculature. Such vascular remodeling can be associated with inflammation, shear stress, and hypoxia-conditions commonly seen in patients with lung diseases. Particularly, the overproduction of reactive oxygen species (ROS) in the diseased lungs contributes greatly to pulmonary vascular remodeling. ROS play an important role in vascular homeostasis, yet excessive ROS can alter pulmonary vasculature and impair lung function, as implicated in COPD at all stages. Increased inflammatory cell infiltration and endothelial dysfunction both correspond to the severity of COPD. As a byproduct of vascular remodeling, pulmonary hypertension negatively affects the long-term survival rate of COPD patients. While there is currently no cure for COPD, several treatment options have focused on alleviating COPD symptoms. Interventions such as long-term oxygen therapy, endothelium-targeted treatment, and pharmacological therapies show promising results in improving the life span of COPD patients and attenuating the progression of pulmonary hypertension. In this chapter, we aim to discuss the contributing factors of pulmonary vascular remodeling in COPD with an emphasis on the ROS, as well as potential redox treatments for COPD-related vascular remodeling.

The Expression and Clinical Outcome of pCHK2-Thr68 and pCDC25C-Ser216 in Breast Cancer.

Checkpoint kinase 2 (CHK2) and cell division cycle 25C (CDC25C) are two proteins involved in the DNA damage response pathway, playing essential roles in maintaining genome integrity. As one of the major hallmarks of abnormal cellular division, genomic instability occurs in most cancers. In this study, we identified the functional expression of pCHK2-Thr68 and pCDC25C-Ser216 in breast cancer, as well as its association with breast cancer survival. Tissue microarray analysis using immunohistochemistry was constructed to identify the expression of pCHK2-Thr68 and pCDC25C-Ser216 in 292 female breast cancer patients. The relationship among protein expression, clinicopathological factors (e.g., human epidermal growth factor receptor 2 (HER 2), tumor size, tumor-node-metastasis (TNM) classification), and overall survival of the breast cancer tissues were analyzed using Pearson's χ-square (χ²) test, Fisher's exact test, multivariate logistic regression and Kaplan-Meier survival analysis. Significantly higher expressions of pCHK2-Thr68 and pCDC25C-Ser216 were observed in the nucleus of the breast cancer cells compared to the paracancerous tissue (pCHK2-Thr68, 20.38% vs. 0%; pCDC25C-Ser216, 82.26% vs. 24.24%). The expression of pCHK2-Thr68 and pCDC25C-Ser216 in breast cancer showed a positive linear correlation (p = 0.026). High expression of pCHK2-Thr68 was associated with decreased patient survival (p = 0.001), but was not an independent prognostic factor. Our results suggest that pCHK2-Thr68 and pCDC25C-Ser216 play important roles in breast cancer and may be potential treatment targets.

Glycosphingolipid synthesis requires FAPP2 transfer of glucosylceramide.

The molecular machinery responsible for the generation of transport carriers moving from the Golgi complex to the plasma membrane relies on a tight interplay between proteins and lipids. Among the lipid-binding proteins of this machinery, we previously identified the four-phosphate adaptor protein FAPP2, the pleckstrin homology domain of which binds phosphatidylinositol 4-phosphate and the small GTPase ARF1. FAPP2 also possesses a glycolipid-transfer-protein homology domain. Here we show that human FAPP2 is a glucosylceramide-transfer protein that has a pivotal role in the synthesis of complex glycosphingolipids, key structural and signalling components of the plasma membrane. The requirement for FAPP2 makes the whole glycosphingolipid synthetic pathway sensitive to regulation by phosphatidylinositol 4-phosphate and ARF1. Thus, by coupling the synthesis of glycosphingolipids with their export to the cell surface, FAPP2 emerges as crucial in determining the lipid identity and composition of the plasma membrane.

Recruitment of NAADP-sensitive acidic Ca2+ stores by glutamate.

NAADP (nicotinic acid-adenine dinucleotide phosphate) is an unusual second messenger thought to mobilize acidic Ca(2+) stores, such as lysosomes or lysosome-like organelles, that are functionally coupled to the ER (endoplasmic reticulum). Although NAADP-sensitive Ca(2+) stores have been described in neurons, the physiological cues that recruit them are not known. Here we show that in both hippocampal neurons and glia, extracellular application of glutamate, in the absence of external Ca(2+), evoked cytosolic Ca(2+) signals that were inhibited by preventing organelle acidification or following osmotic bursting of lysosomes. The sensitivity of both cell types to glutamate correlated well with lysosomal Ca(2+) content. However, interfering with acidic compartments was largely without effect on the Ca(2+) content of the ER or Ca(2+) signals in response to ATP. Glutamate but not ATP elevated cellular NAADP levels. Our results provide evidence for the agonist-specific recruitment of NAADP-sensitive Ca(2+) stores by glutamate. This links the actions of NAADP to a major neurotransmitter in the brain.

Effects of Pre-Hospital Antiplatelet Therapy on the Incidence of ARDS.

BACKGROUND: Clinical observations on the potential of pre-hospital antiplatelet therapy in preventing ARDS have been inconsistent. To further the correlation between antiplatelet therapy and ARDS, we conducted a meta-analysis to evaluate the effects of pre-hospital antiplatelet therapy on subjects with ARDS. METHODS: A literature search in major data banks was performed. We included prospective and retrospective cohorts, case-control trials, and randomized controlled trials that compared the ARDS incidence in subjects with or without pre-hospital antiplatelet agents. RESULTS: Meta-analysis of 7 studies (a total of 30,291 subjects) showed significantly lower odds of ARDS in the pre-hospital antiplatelet therapy group compared with subjects with no pre-hospital antiplatelet therapy (odds ratio 0.68, 95% CI 0.56-0.83; P < .001). However, ARDS mortalities in the hospital and ICUs were not affected. CONCLUSIONS: These findings indicated that pre-hospital antiplatelet therapy was associated with a reduced rate of ARDS but had no effect on the mortality in the subjects at high risk.

Correction: Redox correlation in muscle lengthening and immune response in eccentric exercise.

[This corrects the article DOI: 10.1371/journal.pone.0208799.].

Hypoxic Preconditioning Attenuates Reoxygenation-Induced Skeletal Muscle Dysfunction in Aged Pulmonary TNF-α Overexpressing Mice.

Aim: Skeletal muscle subjected to hypoxia followed by reoxygenation is susceptible to injury and subsequent muscle function decline. This phenomenon can be observed in the diaphragm during strenuous exercise or in pulmonary diseases such as chronic obstructive pulmonary diseases (COPD). Previous studies have shown that PO2 cycling or hypoxic preconditioning (HPC), as it can also be referred to as, protects muscle function via mechanisms involving reactive oxygen species (ROS). However, this HPC protection has not been fully elucidated in aged pulmonary TNF-α overexpressing (Tg+) mice (a COPD-like model). We hypothesize that HPC can exert protection on the diaphragms of Tg+ mice during reoxygenation through pathways involving ROS/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/extracellular signal regulated kinase (ERK), as well as the downstream activation of mitochondrial ATP-sensitive potassium channel (mitoKATP) and inhibition of mitochondrial permeability transition pore (mPTP). Methods: Isolated Tg+ diaphragm muscle strips were pre-treated with inhibitors for ROS, PI3K, Akt, ERK, or a combination of mitoKATP inhibitor and mPTP opener, respectively, prior to HPC. Another two groups of muscles were treated with either mitoKATP activator or mPTP inhibitor without HPC. Muscles were treated with 30-min hypoxia, followed by 15-min reoxygenation. Data were analyzed by multi-way ANOVA and expressed as means ± SE. Results: Muscle treated with HPC showed improved muscle function during reoxygenation (n = 5, p < 0.01). Inhibition of ROS, PI3K, Akt, or ERK abolished the protective effect of HPC. Simultaneous inhibition of mitoKATP and activation of mPTP also diminished HPC effects. By contrast, either the opening of mitoKATP channel or the closure of mPTP provided a similar protective effect to HPC by alleviating muscle function decline, suggesting that mitochondria play a role in HPC initiation (n = 5; p < 0.05). Conclusion: Hypoxic preconditioning may protect respiratory skeletal muscle function in Tg+ mice during reoxygenation through redox-sensitive signaling cascades and regulations of mitochondrial channels.

Redox correlation in muscle lengthening and immune response in eccentric exercise.

This study was designed to examine the potential involvement of reactive oxygen species in skeletal muscle dysfunction linked with stretching in a mouse model and to explore the effects of combined antioxidant intake on peripheral leukocyte apoptosis following eccentrically-biased downhill runs in human subjects. In the mouse model, diaphragmatic muscle was stretched by 30% of its optimal length, followed by 5-min contraction. Muscle function and extracellular reactive oxygen species release was measured ex vivo. In human models, participants performed two trials of downhill running either with or without antioxidant supplementation, followed by apoptotic assay of inflammatory cells in the blood. The results showed that stretch led to decreased muscle function and prominent ROS increase during muscle contraction. In human models, we observed an elevation in circulating leukocyte apoptosis 24-48 hours following acute downhill runs. However, there is an attenuated leukocyte apoptosis following the second bout of downhill run. Interestingly, the combination of ascorbic acid (vitamin C) and α-tocopherol (vitamin E) supplementation attenuated the decrease in B-cell lymphoma 2 (Bcl-2) at 24 hours following acute downhill running. These data collectively suggest that significant ROS formation can be induced by muscle-lengthening associated with eccentric exercise, which is accompanied by compromised muscle function. The combination of antioxidants supplementation appears to have a protective role via the attenuation of decrease in anti-apoptotic protein.

Role of ROS and Nutritional Antioxidants in Human Diseases.

The overproduction of reactive oxygen species (ROS) has been implicated in the development of various chronic and degenerative diseases such as cancer, respiratory, neurodegenerative, and digestive diseases. Under physiological conditions, the concentrations of ROS are subtlety regulated by antioxidants, which can be either generated endogenously or externally supplemented. A combination of antioxidant-deficiency and malnutrition may render individuals more vulnerable to oxidative stress, thereby increasing the risk of cancer occurrence. In addition, antioxidant defense can be overwhelmed during sustained inflammation such as in chronic obstructive pulmonary diseases, inflammatory bowel disease, and neurodegenerative disorders, cardiovascular diseases, and aging. Certain antioxidant vitamins, such as vitamin D, are essential in regulating biochemical pathways that lead to the proper functioning of the organs. Antioxidant supplementation has been shown to attenuate endogenous antioxidant depletion thus alleviating associated oxidative damage in some clinical research. However, some results indicate that antioxidants exert no favorable effects on disease control. Thus, more studies are warranted to investigate the complicated interactions between ROS and different types of antioxidants for restoration of the redox balance under pathologic conditions. This review highlights the potential roles of ROS and nutritional antioxidants in the pathogenesis of several redox imbalance-related diseases and the attenuation of oxidative stress-induced damages.

Potential roles of microRNAs and ROS in colorectal cancer: diagnostic biomarkers and therapeutic targets.

As one of the most commonly diagnosed cancers worldwide, colorectal adenocarcinoma often occurs sporadically in individuals aged 50 or above and there is an increase among younger patients under 50. Routine screenings are recommended for this age group to improve early detection. The multifactorial etiology of colorectal cancer consists of both genetic and epigenetic factors. Recently, studies have shown that the development and progression of colorectal cancer can be attributed to aberrant expression of microRNA. Reactive oxygen species (ROS) that play a key role in cancer cell survival, can also lead to carcinogenesis and cancer exacerbations. Given the rapid accumulating knowledge in the field, an updated review regarding microRNA and ROS in colorectal cancer is necessary. An extensive literature search has been conducted in PubMed/Medline databases to review the roles of microRNAs and ROS in colorectal cancer. Unique microRNA expression in tumor tissue, peripheral blood, and fecal samples from patients with colorectal cancer is outlined. Therapeutic approaches focusing on microRNA and ROS in colorectal cancer treatment is also delineated. This review aims to summarize the newest knowledge on the pathogenesis of colorectal cancer in the hopes of discovering novel diagnostic biomarkers and therapeutic techniques.

Historical role of alpha-1-antitrypsin deficiency in respiratory and hepatic complications.

Alpha-1-antitrypsin (AAT) deficiency is a heritable disease that is commonly associated with complications in the respiratory and hepatic systems. AAT acts as a regulatory enzyme that primarily inhibits neutrophil elastase activity thus protecting tissues from proteolytic damage after inflammation. This paper provides a historical review of the discovery, classification, phenotypic expression, and treatment of AAT deficiency. While its pattern of inheritance has been long understood, the underlying mechanism between AAT deficiency and related diseases remains to be elucidated. Most commonly, AAT deficiency is associated with the development of emphysema in the lungs as well as various liver injuries. Cigarette smoke has been shown to be particularly detrimental in AAT deficient individuals during the development of lung disease. Therefore, understanding familial history may be beneficial when educating patients regarding lifestyle choices. While numerous AAT deficient phenotypes exist in the human populations, only specific variants have been proven to markedly predispose individuals to lung and liver disorders. The exact relationship between AAT levels and the aforementioned diseases is an essential area of further research. It is imperative that clinicians and researchers alike strive to standardize diagnostic criteria and develop safe and effective therapies for this genetic disease.

Redox Mechanism of Reactive Oxygen Species in Exercise.

It is well known that regular exercise can benefit health by enhancing antioxidant defenses in the body. However, unaccustomed and/or exhaustive exercise can generate excessive reactive oxygen species (ROS), leading to oxidative stress-related tissue damages and impaired muscle contractility. ROS are produced in both aerobic and anaerobic exercise. Mitochondria, NADPH oxidases and xanthine oxidases have all been identified as potential contributors to ROS production, yet the exact redox mechanisms underlying exercise-induced oxidative stress remain elusive. Interestingly, moderate exposure to ROS is necessary to induce body's adaptive responses such as the activation of antioxidant defense mechanisms. Dietary antioxidant manipulation can also reduce ROS levels and muscle fatigue, as well as enhance exercise recovery. To elucidate the complex role of ROS in exercise, this review updates on new findings of ROS origins within skeletal muscles associated with various types of exercises such as endurance, sprint and mountain climbing. In addition, we will examine the corresponding antioxidant defense systems as well as dietary manipulation against damages caused by ROS.

Paeonol Protects Rat Heart by Improving Regional Blood Perfusion during No-Reflow.

No-reflow phenomenon, defined as inadequate perfusion of myocardium without evident artery obstruction, occurs at a high incidence after coronary revascularization. The mechanisms underlying no-reflow is only partially understood. It is commonly caused by the swelling of endothelial cells, neutrophil accumulation, and vasoconstriction, which are all related to acute inflammation. Persistent no-reflow can lead to hospitalization and mortality. However, an effective preventive intervention has not yet been established. We have previously found that paeonol, an active extraction from the root of Paeonia suffruticosa, can benefit the heart function by inhibiting tissue damage after ischemia, reducing inflammation, and inducing vasodilatation. To further investigate the potential cardioprotective action of paeonol on no-reflow, healthy male Wistar rats were randomly divided into four groups: sham, ischemia-reperfusion (I/R) injury (left anterior descending coronary artery was ligated for 4 h followed by reperfusion for 8 h), and I/R injury pretreated with paeonol at two different doses. Real-time myocardial contrast echocardiography was used to monitor regional blood perfusion and cardiac functions. Our data indicated that paeonol treatment significantly reduces myocardial infarct area and no-reflow area (n = 8; p < 0.05). Regional myocardial perfusion (A·ß) and cardiac functions such as ejection fraction, stroke volume, and fractional shortening were elevated by paeonol (n = 8; p < 0.05). Paeonol also lowered the serum levels of lactate dehydrogenase, creatine kinase, cardiac troponin T, and C-reactive protein, as indices of myocardial injury. Paeonol exerts beneficial effects on attenuating I/R-associated no-reflow injuries, and may be considered as a potential preventive treatment for cardiac diseases or post-coronary revascularization in which no-reflow often occurs.

Fine particulate matter in acute exacerbation of COPD.

Chronic obstructive pulmonary disease (COPD) is a common airway disorder. In particular, acute exacerbations of COPD (AECOPD) can significantly reduce pulmonary function. The majority of AECOPD episodes are attributed to infections, although environmental stress also plays a role. Increasing urbanization and associated air pollution, especially in developing countries, have been shown to contribute to COPD pathogenesis. Elevated levels of particulate matter (PM) in polluted air are strongly correlated with the onset and development of various respiratory diseases. In this review, we have conducted an extensive literature search of recent studies of the role of PM2.5 (fine PM) in AECOPD. PM2.5 leads to AECOPD via inflammation, oxidative stress (OS), immune dysfunction, and altered airway epithelial structure and microbiome. Reducing PM2.5 levels is a viable approach to lower AECOPD incidence, attenuate COPD progression and decrease the associated healthcare burden.

Molecular Characterization of Reactive Oxygen Species in Myocardial Ischemia-Reperfusion Injury.

Myocardial ischemia-reperfusion (I/R) injury is experienced by individuals suffering from cardiovascular diseases such as coronary heart diseases and subsequently undergoing reperfusion treatments in order to manage the conditions. The occlusion of blood flow to the tissue, termed ischemia, can be especially detrimental to the heart due to its high energy demand. Several cellular alterations have been observed upon the onset of ischemia. The danger created by cardiac ischemia is somewhat paradoxical in that a return of blood to the tissue can result in further damage. Reactive oxygen species (ROS) have been studied intensively to reveal their role in myocardial I/R injury. Under normal conditions, ROS function as a mediator in many cell signaling pathways. However, stressful environments significantly induce the generation of ROS which causes the level to exceed body's antioxidant defense system. Such altered redox homeostasis is implicated in myocardial I/R injury. Despite the detrimental effects from ROS, low levels of ROS have been shown to exert a protective effect in the ischemic preconditioning. In this review, we will summarize the detrimental role of ROS in myocardial I/R injury, the protective mechanism induced by ROS, and potential treatments for ROS-related myocardial injury.

The Role of Oxidative Stress-Induced Epigenetic Alterations in Amyloid-ß Production in Alzheimer's Disease.

An increasing number of studies have proposed a strong correlation between reactive oxygen species (ROS)-induced oxidative stress (OS) and the pathogenesis of Alzheimer's disease (AD). With over five million people diagnosed in the United States alone, AD is the most common type of dementia worldwide. AD includes progressive neurodegeneration, followed by memory loss and reduced cognitive ability. Characterized by the formation of amyloid-beta (Aß) plaques as a hallmark, the connection between ROS and AD is compelling. Analyzing the ROS response of essential proteins in the amyloidogenic pathway, such as amyloid-beta precursor protein (APP) and beta-secretase (BACE1), along with influential signaling programs of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and c-Jun N-terminal kinase (JNK), has helped visualize the path between OS and Aß overproduction. In this review, attention will be paid to significant advances in the area of OS, epigenetics, and their influence on Aß plaque assembly. Additionally, we aim to discuss available treatment options for AD that include antioxidant supplements, Asian traditional medicines, metal-protein-attenuating compounds, and histone modifying inhibitors.

Reactive oxygen species in redox cancer therapy.

The role of reactive oxygen species (ROS) in cancer cells has been intensively studied for the past two decades. Cancer cells mostly have higher basal ROS levels than their normal counterparts. The induction of ROS has been shown to be associated with cancer development, metastasis, progression, and survival. Various therapeutic approaches targeting intracellular ROS levels have yielded mixed results. As widely accepted dietary supplements, antioxidants demonstrate both ROS scavenging ability and anti-cancer characteristics. However, antioxidants may not always be safe to use since excessive intake of antioxidants could lead to serious health concerns. In this review, we have evaluated the production and scavenging systems of ROS in cells, as well as the beneficial and harmful roles of ROS in cancer cells. We also examine the effect of antioxidants in cancer treatment, the effect of combined treatment of antioxidants with traditional cancer therapies, and the side effects of excessive antioxidant intake.

Heart failure with preserved ejection fraction: Defining the function of ROS and NO.

The understanding of complex molecular mechanisms underlying heart failure (HF) is constantly under revision. Recent research has paid much attention to understanding the growing number of patients that exhibit HF symptoms yet have an ejection fraction similar to a normal phenotype. Termed heart failure with preserved ejection fraction (HFpEF), this novel hypothesis traces its roots to a proinflammatory state initiated in part by the existence of comorbidities that create a favorable environment for the production of reactive oxygen species (ROS). Triggering a cascade that involves reduced nitric oxide (NO) availability, elevated ROS levels in the coronary endothelium eventually contribute to hypertrophy and increased resting tension in cardiomyocytes. Improved understanding of the molecular pathways associated with HFpEF has led to studies that concentrate on reducing ROS production in the heart, boosting NO availability, and increasing exercise capacity for HFpEF patients. This review will explore the latest research into the role of ROS and NO in the progression of HFpEF, as well as discuss the encouraging results of numerous therapeutic studies.

Molecular Regulation of Toll-like Receptors in Asthma and COPD.

Asthma and chronic obstructive pulmonary disease (COPD) have both been historically associated with significant morbidity and financial burden. These diseases can be induced by several exogenous factors, such as pathogen-associated molecular patterns (PAMPs) (e.g., allergens and microbes). Endogenous factors, including reactive oxygen species, and damage-associated molecular patterns (DAMPs) recognized by toll-like receptors (TLRs), can also result in airway inflammation. Asthma is characterized by the dominant presence of eosinophils, mast cells, and clusters of differentiation (CD)4(+) T cells in the airways, while COPD typically results in the excessive formation of neutrophils, macrophages, and CD8(+) T cells in the airways. In both asthma and COPD, in the respiratory tract, TLRs are the primary proteins of interest associated with the innate and adaptive immune responses; hence, multiple treatment options targeting TLRs are being explored in an effort to reduce the severity of the symptoms of these disorders. TLR-mediated pathways for both COPD and asthma have their similarities and differences with regards to cell types and the pro-inflammatory cytotoxins present in the airway. Because of the complex TLR cascade, a variety of treatments have been used to minimize airway hypersensitivity and promote bronchodilation. Although unsuccessful at completely alleviating COPD and severe asthmatic symptoms, new studies are focused on possible targets within the TLR cascade to ameliorate airway inflammation.