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Molecular Regulation and Therapeutic Potential of Thermogenic Fat Cells

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198696 Year: Pages: 127 DOI: 10.3389/978-2-88919-869-6 Language: English
Publisher: Frontiers Media SA
Subject: Internal medicine --- Medicine (General)
Added to DOAB on : 2016-01-19 14:05:46
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Obesity has emerged as a major threat to public health in both the western and developing world. Essentially a disorder of energy balance, obesity occurs when energy intake and storage exceeds expenditure. Much of energy homeostasis depends on the activity and function of adipose tissue. Adipocytes in mammals fall into two categories classified by their primary functions: white fat cells that mediate energy storage and thermogenic fat cells that counteract hypothermia and obesity through adaptive thermogenesis. Whereas white fat and its function as an energy reservoir and endocrine organ have been studied for decades and are relatively well understood, until recently many aspects of the thermogenic fat biology have remained elusive. Accumulating evidence supports the hypothesis that thermogenic fat cells arise from at least two different developmental origins: the ones of a skeletal muscle-like lineage are now called “classical” brown fat cells, and the rest of the thermogenic fat cells are normally referred to as the beige fat cells. The last decade has witnessed an explosion of interest and studies focusing on the regulation of thermogenic fat cells and potential therapeutics targeting these adipocytes. Here we summarize the recent advancements in our understanding of these metabolically active fat cells.

Proceedings of the 3rd International Conference on Genetics of Aging and Longevity

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199266 Year: Pages: 88 DOI: 10.3389/978-2-88919-926-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Genetics
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In this book, we present a collection of articles covering a wide range of current aging research and highlighting its prospects and future directions. These articles are based on or related to the topics of the 3rd International Conference «Genetics of aging and longevity». The Conference took place 6-10 April, 2014 in Sochi, the city located on the Black Sea coast near the Caucasian mountains, in Russia. Top gerontologists and geneticists from 31 countries around the world came together to discuss current problems in many areas related to the genetics of longevity and mechanisms of aging. We would like to thank those of them who contributed to this e-Book by sharing latest achievements, ideas and hypotheses. We hope that this e-Book will come to notice of scientists interested in the development of genetics of aging and longevity and in the search for life-beneficial environments and life-prolonging interventions.

Obesity and Diabetes: Energy Regulation by Free Fatty Acid Receptors

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197477 Year: Pages: 45 DOI: 10.3389/978-2-88919-747-7 Language: English
Publisher: Frontiers Media SA
Subject: Internal medicine --- Medicine (General)
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Food intake regulates energy balance and its dysregulation leads to metabolic disorder, such as obesity and diabetes. During feeding, free fatty acids (FFAs) are not only essential nutrients but also act as signaling molecules in various cellular processes. Recently, several orphan G protein-coupled receptors (GPCRs) that act as FFA receptors (FFARs) have been identified; GPR40/FFAR1, GPR119, and GPR120 are activated by medium- and long-chain FFAs. GPR84 is activated by medium-chain FFAs. GPR41/FFAR3 and GPR43/FFAR2 are activated by short-chain FFAs. These FFARs have come to be regarded as new drug targets for metabolic disorder such as obesity and type 2 diabetes, because a number of pharmacological and physiological studies have shown that these receptors are primarily involved in the energy metabolism in various tissues; insulin secretion, gastrointestinal hormone secretion, adipokine secretion, regulation of inflammation, regulation of autonomic nervous system, relation to gut microbiota, and so on. This Research Topic provides a comprehensive overview of the energy regulation by free fatty acid receptors and a new prospect for treatment of metabolic disorder such as obesity and type 2 diabetes.

Current Challenges in Modeling Cellular Metabolism

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197545 Year: Pages: 115 DOI: 10.3389/978-2-88919-754-5 Language: English
Publisher: Frontiers Media SA
Subject: Biology --- Science (General) --- Biotechnology --- General and Civil Engineering
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Mathematical and computational models play an essential role in understanding the cellular metabolism. They are used as platforms to integrate current knowledge on a biological system and to systematically test and predict the effect of manipulations to such systems. The recent advances in genome sequencing techniques have facilitated the reconstruction of genome-scale metabolic networks for a wide variety of organisms from microbes to human cells. These models have been successfully used in multiple biotechnological applications. Despite these advancements, modeling cellular metabolism still presents many challenges. The aim of this Research Topic is not only to expose and consolidate the state-of-the-art in metabolic modeling approaches, but also to push this frontier beyond the current edge through the introduction of innovative solutions. The articles presented in this e-book address some of the main challenges in the field, including the integration of different modeling formalisms, the integration of heterogeneous data sources into metabolic models, explicit representation of other biological processes during phenotype simulation, and standardization efforts in the representation of metabolic models and simulation results.

Salicylic Acid Signaling Networks

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198276 Year: Pages: 188 DOI: 10.3389/978-2-88919-827-6 Language: English
Publisher: Frontiers Media SA
Subject: Botany --- Science (General)
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The small phenolic compound salicylic acid (SA) is critical for plant defense against a broad spectrum of pathogens. SA is also involved in multi-layered defense responses, from pathogen-associated molecular pattern triggered basal defense, resistance gene-mediated defense, to systemic acquired resistance. Recent decades have witnessed tremendous progress towards our understanding of SA-mediated signaling networks. Many genes have been identified to have direct or indirect effect on SA biosynthesis or to regulate SA accumulation. Several SA receptors have been identified and characterization of these receptors has shed light on the mechanisms of SA-mediated defense signaling, which encompass chromosomal remodeling, DNA repair, epigenetics, to transcriptional reprogramming. Molecules from plant-associated microbes have been identified, which manipulate SA levels and/or SA signaling. SA does not act alone. It engages in crosstalk with other signaling pathways, such as those mediated by other phytohormones, in an agonistic or antagonistic manner, depending on hormones and pathosystems. Besides affecting plant innate immunity, SA has also been implicated in other cellular processes, such as flowering time determination, lipid metabolism, circadian clock control, and abiotic stress responses, possibly contributing to the regulation of plant development. The multifaceted function of SA makes it critically important to further identify genes involved in SA signaling networks, understand their modes of action, and delineate interactions among the components of SA signaling networks. In addition, genetic manipulation of genes involved in SA signaling networks has also provided a promising approach to enhance disease resistance in economically important plants. This ebook collects articles in the Research Topic "Salicylic Acid Signaling Networks". For this collection we solicited reviews, perspectives, and original research articles that highlight recent exciting progress on the understanding of molecular mechanisms underlying SA-mediated defense, SA-crosstalk with other pathways and how microbes impact these events.

Redox Homeostasis Managers in Plants under Environmental Stresses

Authors: --- --- --- --- et al.
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198788 Year: Pages: 208 DOI: 10.3389/978-2-88919-878-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Environmental Sciences
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The production of cellular oxidants such as reactive oxygen species (ROS) is an inevitable con-sequence of redox cascades of aerobic metabolism in plants. This milieu is further aggravated by a myriad of adverse environmental conditions that plants, owing to their sessile life-style, have to cope with during their life cycle. Adverse conditions prevent plants reaching their full genetic potential in terms of growth and productivity mainly as a result of accelerated ROS generation-accrued redox imbalances and halted cellular metabolism. In order to sustain ROS-accrued consequences, plants tend to manage a fine homeostasis between the generation and antioxidants-mediated metabolisms of ROS and its reaction products. Well-known for their involvement in the regulation of several non-stress-related processes, redox related components such as proteinaceous thiol members such as thioredoxin, glutaredoxin, and peroxiredoxin proteins, and key soluble redox-compounds namely ascorbate (AsA) and glutathione (GSH) are also listed as efficient managers of cellular redox homeostasis in plants. The management of the cellular redox homeostasis is also contributed by electron carriers and energy metabolism mediators such as non-phosphorylated (NAD+) and the phosphorylated (NADP+) coenzyme forms and their redox couples DHA/AsA, GSSG/GSH, NAD+/NADH and NADP+/NADPH. Moreover, intracellular concentrations of these cellular redox homeostasis managers in plant cells fluctuate with the external environments and mediate dynamic signaling in pant stress responses. This research topic aims to exemplify new information on how redox homeostasis managers are modulated by environmental cues and what potential strategies are useful for improving cellular concentrations of major redox homeostasis managers. Additionally, it also aims to pro-vide readers detailed updates on specific topics, and to highlight so far unexplored aspects in the current context.

Hormonal and Neuroendocrine Regulation of Energy Balance

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198856 Year: Pages: 117 DOI: 10.3389/978-2-88919-885-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Physiology
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Alteration in adequate energy balance maintenance results in serious disturbances such as obesity and its related metabolic disorders. In Mammals, energy balance is homeostatically controlled through hormonal and neuroendocrine systems which cooperation is based on cross-talk between central and peripheral signals. The hypothalamus as well as peripheral hormones among which adipokines from adipose tissue and thyroid hormones play a crucial role in energy homeostasis. Unraveling the physiological, cellular and molecular mechanisms through which hormonal and neuroendocrine systems regulate energy balance has been a long-standing challenge in biology and is now more necessary when considering the world-wide increasing prevalence of obesity. Indeed, recognizing and understanding the biochemical and nutrient signaling pathways contributing to the nervous and endocrine integration of physiological mechanisms involved in the normal and/or abnormal regulation of energy balance is fundamental also to the development of new, effective, and targeted treatments for obesity. Recent studies have highlighted the role of hypothalamic pro-opiomelanocortin-expressing neurons in the regulation of energy homeostasis by controlling energy expenditure and food intake. This is accomplished through a precise balance of production and degradation of a-melanocyte-stimulating hormone, an anorexigenic neuropeptide which is degraded to an inactive form unable to inhibit food intake by the key enzyme prolyl carboxypeptidase (PRCP), thus suggesting that pharmacologic approaches targeting PRCP may provide a novel and effective option for the management of obesity and its associated metabolic disorders. Indeed, efforts have been made to generate potent, brain-penetrant PRCP inhibitors. Weight loss due to negative energy balance is a goal for obese subjects not always reachable by dietary caloric restriction or increased physical activity. Lipid-lowering therapies have been suggested to have potential benefits, however, the establishment of comprehensive therapeutic strategies is still awaited. Recently, it has been reported that thyroid hormone (TH)- derivatives such as 3,5-diiodothyronine and 3-iodothyronamine possess interesting biological activities, opening new perspectives in thyroid physiology and TH derivatives therapeutic usage. Moreover, several studies, focusing on the interaction between thyroid hormone (TH), the autonomic nervous system and the liver, revealed an important role for the hypothalamus in the differential effects of TH on autonomic outflow to peripheral organs controlling energy balance. This Research Topic aims to give a comprehensive and integrate view of the factors involved in the endocrine and neuroendocrine signaling in energy balance regulation to highlight their involvement into physiological processes and regulatory systems as well as their perturbation during pathological processes.

The two-way link between eating behavior and brain metabolism

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197057 Year: Pages: 197 DOI: 10.3389/978-2-88919-705-7 Language: English
Publisher: Frontiers Media SA
Subject: Psychology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
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This research topic collected and connected information concerning both the underlying metabolic mechanisms and consequences of eating behaviors. These two aspects are tremendously important for a better understanding of eating behavior abnormalities as well as for improving education on eating disorders and behaviors.

The Coevolution of IDO1 and AhR in the Emergence of Regulatory T Cells in Mammals

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197293 Year: Pages: 89 DOI: 10.3389/978-2-88919-729-3 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
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Indoleamine 2,3-dioxygenase (IDO1) is an ancestral enzyme that, initially confined to the regulation of tryptophan availability in local tissue microenvironments, is now considered to play a wider role that extends to homeostasis and plasticity of the immune system. Thus IDO biology has implications for many aspects of immunopathology, including viral infections, neoplasia, autoimmunity, and chronic inflammation. Its immunoregulatory effects are mainly mediated by dendritic cells (DCs) and involve not only tryptophan deprivation but also production of kynurenines that act on IDO- DCs, thus rendering an otherwise stimulatory DC capable of regulatory effects, as well as on T cells. The aryl hydrocarbon receptor (AhR) is a ligand-operated transcription factor originally recognized as the effector mediating the pathologic effects of dioxins and other pollutants. However, it is now well established that AhR activation by endogenous ligands can produce immunoregulatory effects. The IDO1 mechanism appears to have been selected through phylogenesis primarily to prevent overreacting responses to TLR-recognized pathogen-associated molecular patterns, and only later did it become involved in the response to T cell receptor-recognized antigens. As a result, in mammals, IDO1 has become pivotal in fetomaternal tolerance, at a time when regulatory T cells emerged to meet the same need, namely protecting the fetus. IDO1 and regulatory T (Treg) cells may have then coevolved to broaden their function well beyond their initial task of protecting the fetus, such that, in acquired immunity, IDO1 (with its dual enzymic and signaling function) has turned into an important component of the peripheral generation and effector function of regulatory T cells. AhR, in turn, which has a role in regulatory T-cell generation, is presumed to have evolved from invertebrates, where it served a ligand-independent role in normal development processes. Evolution of the receptor in vertebrates resulted in the ability to bind structurally different ligands, including xenobiotics and microbiota-derived catabolites. Considering the inability of invertebrate AhR homologs to bind dioxins, the adaptive role of the AhR to act as a regulator of xenobiotic-metabolizing enzymes may have been a vertebrate innovation, to later acquire an additional immune regulatory role by coevolutive pressure in mammals by IDO1 and regulatory T cells. Thus an entirely new paradigm in immunology, and more specifically in immune tolerance, is the coevolution of three systems, namely, the IDO1 mechanism, AhR-driven gene transcription, and T-cell regulatory activity, that originating from the initial need of protecting the fetus in mammals, have later turned into a pivotal mechanism of peripheral tolerance in autoimmunity, transplantation, and neoplasia.

Polar Microbiology: Recent Advances and Future Perspectives

ISBN: 9783038421757 9783038421764 Year: Pages: 466 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2016-05-12 11:49:37
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