scholarly journals OCTN Cation Transporters in Health and Disease

2013 ◽  
Vol 18 (8) ◽  
pp. 851-867 ◽  
Author(s):  
Lorena Pochini ◽  
Mariafrancesca Scalise ◽  
Michele Galluccio ◽  
Cesare Indiveri
Keyword(s):  
Large Scale ◽  
Intact Cell ◽  
Organic Cation Transporter ◽  
Carnitine Deficiency ◽  
Transmembrane Segments ◽  
Pharmacological Targets ◽  
Carnitine Transport ◽  
Health And Disease ◽  
Inflammatory Bowel ◽  
Molecular Bases

The three members of the organic cation transporter novel subfamily are known to be involved in interactions with xenobiotic compounds. These proteins are characterized by 12 transmembrane segments connected by nine short loops and two large hydrophilic loops. It has been recently pointed out that acetylcholine is a physiological substrate of OCTN1. Its transport could be involved in nonneuronal cholinergic functions. OCTN2 maintains the carnitine homeostasis, resulting from intestinal absorption, distribution to tissues, and renal excretion/reabsorption. OCTN3, identified only in mouse, mediates also carnitine transport. OCTN1 and OCTN2 are associated with several pathologies, such as inflammatory bowel disease, primary carnitine deficiency, diabetes, neurological disorders, and cancer, thus representing useful pharmacological targets. The function and interaction with drugs of OCTNs have been studied in intact cell systems and in proteoliposomes. The latter experimental model enables reduced interference from other transporters or enzyme pathways. Using proteoliposomes, the molecular bases of toxicity of some drugs have recently been revealed. Therefore, proteoliposomes represent a promising experimental tool suitable for large-scale molecular screening of interactions of OCTNs with chemicals regarding human health.

Functional and pharmacological characterization of human Na+-carnitine cotransporter hOCTN2

2000 ◽  
Vol 279 (3) ◽  
pp. F584-F591 ◽  
Author(s):  
Carsten A. Wagner ◽  
Ulrike Lükewille ◽  
Simone Kaltenbach ◽  
Ivano Moschen ◽  
Angelika Bröer ◽  
...  
Keyword(s):  
Organic Cation ◽  
Organic Cation Transporter ◽  
Carnitine Deficiency ◽  
Significant Inhibition ◽  
Xenopus Laevis Oocytes ◽  
Channel Blockers ◽  
Pharmacological Characterization ◽  
Transporter Family ◽  
Carnitine Transport ◽  
Induced Currents

l-Carnitine is essential for the translocation of acyl-carnitine into the mitochondria for β-oxidation of long-chain fatty acids. It is taken up into the cells by the recently cloned Na+-driven carnitine organic cation transporter OCTN2. Here we expressed hOCTN2 in Xenopus laevis oocytes and investigated with two-electrode voltage- clamp and flux measurements its functional and pharmacological properties as a Na+-carnitine cotransporter. l-carnitine transport was electrogenic. The l-carnitine-induced currents were voltage and Na+ dependent, with half-maximal currents at 0.3 ± 0.1 mM Na+ at −60 mV. Furthermore,l-carnitine-induced currents were pH dependent, decreasing with acidification. In contrast to other members of the organic cation transporter family, hOCTN2 functions as a Na+-coupled carnitine transporter. Carnitine transport was stereoselective, with an apparent Michaelis-Menten constant ( K m) of 4.8 ± 0.3 μM for l-carnitine and 98.3 ± 38.0 μM for d-carnitine. The substrate specificity of hOCTN2 differs from rOCT-1 and hOCT-2 as hOCTN2 showed only small currents with classic OCT substrates such as choline or tetraethylammonium; by contrast hOCTN2 mediated transport of betaine. hOCTN2 was inhibited by several drugs known to induce secondary carnitine deficiency. Most potent blockers were the antibiotic emetine and the ion channel blockers quinidine and verapamil. The apparent IC50 for emetine was 4.2 ± 1.2 μM. The anticonvulsant valproic acid did not induce a significant inhibition of carnitine transport, pointing to a different mode of action. In summary, hOCTN2 mediates electrogenic Na+-dependent stereoselective high-affinity transport ofl-carnitine and Na+. hOCTN2 displays transport properties distinct from other members of the OCT family and is directly inhibited by several substances known to induce systemic carnitine deficiency.

scholarly journals GutCyc: a Multi-Study Collection of Human Gut Microbiome Metabolic Models

2016 ◽  
Author(s):  
Aria S. Hahn ◽  
Tomer Altman ◽  
Kishori M. Konwar ◽  
Niels W. Hanson ◽  
Dongjae Kim ◽  
...  
Keyword(s):  
Gut Microbiome ◽  
Large Scale ◽  
High Throughput Sequencing ◽  
Human Microbiome ◽  
Therapeutic Interventions ◽  
Human Gut ◽  
Human Gut Microbiome ◽  
Disease States ◽  
Health And Disease ◽  
Inflammatory Bowel

AbstractAdvances in high-throughput sequencing are reshaping how we perceive microbial communities inhabiting the human body, with implications for therapeutic interventions. Several large-scale datasets derived from hundreds of human microbiome samples sourced from multiple studies are now publicly available. However, idiosyncratic data processing methods between studies introduce systematic differences that confound comparative analyses. To overcome these challenges, we developed GUTCYC, a compendium of environmental pathway genome databases constructed from 418 assembled human microbiome datasets using METAPATHWAYS, enabling reproducible functional metagenomic annotation. We also generated metabolic network reconstructions for each metagenome using the PATHWAY TOOLS software, empowering researchers and clinicians interested in visualizing and interpreting metabolic pathways encoded by the human gut microbiome. For the first time, GUTCYC provides consistent annotations and metabolic pathway predictions, making possible comparative community analyses between health and disease states in inflammatory bowel disease, Crohn’s disease, and type 2 diabetes. GUTCYC data products are searchable online, or may be downloaded and explored locally using METAPATHWAYS and PATHWAY TOOLS.

scholarly journals Microbial contributions to oxalate metabolism in health and disease

2020 ◽  
Author(s):  
Menghan Liu ◽  
Joseph C. Devlin ◽  
Jiyuan Hu ◽  
Angelina Volkova ◽  
Thomas W. Battaglia ◽  
...  
Keyword(s):  
Intestinal Microbiota ◽  
Large Scale ◽  
Degradation Pathways ◽  
Omics Data ◽  
Oxalobacter Formigenes ◽  
Increased Risk ◽  
Health And Disease ◽  
Inflammatory Bowel ◽  
Oxalate Metabolism

AbstractOver-accumulation of oxalate in humans may lead to nephrolithiasis and nephrocalcinosis. Humans lack endogenous oxalate degradation pathways (ODP), but intestinal microbiota can degrade oxalate and protect against its absorption. However, the particular microbes that actively degrade oxalate in vivo are ill-defined, which restricts our ability to disentangle the underlying taxonomic contributions. Here we leverage large-scale multi-omics data (>3000 samples from >1000 subjects) to show that the human microbiota in health harbors diverse ODP-encoding microbial species, but an oxalate autotroph-Oxalobacter formigenes- dominates this function transcriptionally. Patients with Inflammatory Bowel Disease (IBD) are at significantly increased risk for disrupted oxalate homeostasis and calcium-oxalate nephrolithiasis. Here, by analyzing multi-omics data from the iHMP-IBD study, we demonstrate that the oxalate degradation function conferred by the intestinal microbiota is severely impaired in IBD patients. In parallel, the enteric oxalate levels of IBD patients are significantly elevated and associated with intestinal disease severity, which is consistent with the clinically known nephrolithiasis risk. The specific changes in ODP expression by several important taxa suggest that they play different roles in the IBD-induced nephrolithiasis risk.

scholarly journals Novel gut pathobionts confound results in a widely used mouse model of human inflammatory disease

2021 ◽  
Author(s):  
Samuel C. Forster ◽  
Simon Clare ◽  
Benjamin S. Beresford-Jones ◽  
Katherine Harcourt ◽  
George Notley ◽  
...  
Keyword(s):  
Mouse Model ◽  
Mouse Models ◽  
Large Scale ◽  
Bacterial Species ◽  
The Novel ◽  
Host Immune Responses ◽  
Causes Of Disease ◽  
Health And Disease ◽  
Inflammatory Bowel ◽  
Scale Experiment

The mammalian gut microbiota consists of hundreds of anaerobic bacterial species that shape intestinal homeostasis and influence host immune responses. Although the causal roles of specific human gut bacterial species in health and disease are emerging, the role of indigenous gut bacteria in driving immunophenotypic variability in mouse models of human disease remains poorly understood. We performed a large-scale experiment using 579 laboratory mice designed to identify and validate the causes of disease variability in the widely used dextran sulphate sodium (DSS) mouse model of inflammatory bowel disease. Using microbiome analysis, coupled with machine learning and targeted anaerobic culturing, we identified and isolated the novel gut pathobiont species Duncaniella muricolitica and Alistipes okayasuensis and fulfilled Koch’s postulates in mice to show that each pathobiont exerts dominant effects in the DSS model leading to variable treatment responses. We show these pathobiont species are common, but not ubiquitous, in mouse facilities around the world, raising experimental design opportunities for improved mouse models of human intestinal diseases.

Molecular bases of impaired water and ion movements in inflammatory bowel diseases

2009 ◽  
Vol 15 (1) ◽  
pp. 114-127 ◽  
Author(s):  
Olga Martínez-Augustin ◽  
Isabel Romero-Calvo ◽  
María Dolores Suárez ◽  
Antonio Zarzuelo ◽  
Fermín Sánchez de Medina
Keyword(s):  
Inflammatory Bowel Diseases ◽  
Bowel Diseases ◽  
Ion Movements ◽  
Inflammatory Bowel ◽  
Molecular Bases ◽  
Impaired Water

scholarly journals A Potential of microRNAs for High-Content Screening

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Andrius Serva ◽  
Christoph Claas ◽  
Vytaute Starkuviene
Keyword(s):  
Large Scale ◽  
Cellular Processes ◽  
Comprehensive Knowledge ◽  
Functional Models ◽  
Rapid Accumulation ◽  
Health And Disease ◽  
Temporal And Spatial ◽  
And Function ◽  
Functional Analyses ◽  
Immense Potential

In the last years miRNAs have increasingly been recognised as potent posttranscriptional regulators of gene expression. Possibly, miRNAs exert their action on virtually any biological process by simultaneous regulation of numerous genes. The importance of miRNA-based regulation in health and disease has inspired research to investigate diverse aspects of miRNA origin, biogenesis, and function. Despite the recent rapid accumulation of experimental data, and the emergence of functional models, the complexity of miRNA-based regulation is still far from being well understood. In particular, we lack comprehensive knowledge as to which cellular processes are regulated by which miRNAs, and, furthermore, how temporal and spatial interactions of miRNAs to their targets occur. Results from large-scale functional analyses have immense potential to address these questions. In this review, we discuss the latest progress in application of high-content and high-throughput functional analysis for the systematic elucidation of the biological roles of miRNAs.

scholarly journals Biosynthesis of the Essential Fatty Acid Oxidation Cofactor Carnitine Is Stimulated in Heart and Liver after a Single Bout of Exercise in Mice

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Tom L. Broderick ◽  
Frank A. Cusimano ◽  
Chelsea Carlson ◽  
Jeganathan Ramesh Babu
Keyword(s):  
Acute Exercise ◽  
Organic Cation Transporter ◽  
Carnitine Deficiency ◽  
Treadmill Running ◽  
Moderate Intensity ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Single Bout ◽  
Carnitine Uptake

We determined whether one single bout of exercise stimulates carnitine biosynthesis and carnitine uptake in liver and heart. Free carnitine (FC) in plasma was assayed using acetyltransferase and [14C]acetyl-CoA in Swiss Webster mice after 1 hour of moderate-intensity treadmill running or 4 hours and 8 hours into recovery. Liver and heart were removed under the same conditions for measurement of carnitine biosynthesis enzymes (liver butyrobetaine hydroxylase, γ-BBH; heart trimethyllysine dioxygenase, TMLD), organic cation transporter-2 (OCTN2, carnitine transporter), and liver peroxisome proliferator-activated receptor-alpha (PPARα, transcription factor for γ-BBH and OCTN2 synthesis). In exercised mice, FC levels in plasma decreased while heart and liver OCTN2 protein expressed increased, reflecting active uptake of FC. During recovery, the rise in FC to control levels was associated with increased liver γ-BBH expression. Protein expression of PPARα was stimulated in liver after exercise and during recovery. Interestingly, heart TMLD protein was also detected after exercise. Acute exercise stimulates carnitine uptake in liver and heart. The rapid return of FC levels in plasma after exercise indicates carnitine biosynthesis by liver is stimulated to establish carnitine homeostasis. Our results suggest that exercise may benefit patients with carnitine deficiency syndromes.

scholarly journals Hidden in plain sight: What remains to be discovered in the eukaryotic proteome?

2018 ◽  
Author(s):  
Valerie Wood ◽  
Antonia Lock ◽  
Midori A. Harris ◽  
Kim Rutherford ◽  
Jürg Bähler ◽  
...  
Keyword(s):  
Gene Ontology ◽  
Fission Yeast ◽  
Genome Sequencing ◽  
Large Scale ◽  
Biological Process ◽  
Blind Spot ◽  
Model Organisms ◽  
Biological Processes ◽  
Health And Disease

AbstractThe first decade of genome sequencing stimulated an explosion in the characterization of unknown proteins. More recently, the pace of functional discovery has slowed, leaving around 20% of the proteins even in well-studied model organisms without informative descriptions of their biological roles. Remarkably, many uncharacterized proteins are conserved from yeasts to human, suggesting that they contribute to fundamental biological processes. To fully understand biological systems in health and disease, we need to account for every part of the system. Unstudied proteins thus represent a collective blind spot that limits the progress of both basic and applied biosciences.We use a simple yet powerful metric based on Gene Ontology (GO) biological process terms to define characterized and uncharacterized proteins for human, budding yeast, and fission yeast. We then identify a set of conserved but unstudied proteins in S. pombe, and classify them based on a combination of orthogonal attributes determined by large-scale experimental and comparative methods. Finally, we explore possible reasons why these proteins remain neglected, and propose courses of action to raise their profile and thereby reap the benefits of completing the catalog of proteins’ biological roles.

scholarly journals ENIGMA and Global Neuroscience: A Decade of Large-Scale Studies of the Brain in Health and Disease across more than 40 Countries

2019 ◽  
Author(s):  
Paul Thompson ◽  
Neda Jahanshad ◽  
Christopher R. K. Ching ◽  
Lauren Salminen ◽  
Sophia I Thomopoulos ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
22Q11.2 Deletion Syndrome ◽  
Autism Spectrum ◽  
Deletion Syndrome ◽  
Sex And Gender ◽  
Post Traumatic Stress ◽  
Global Alliance ◽  
Compulsive Disorder ◽  
Health And Disease

This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1,400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of “big data” (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA’s activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive and psychosocial factors.

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