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LuxR Solos are Becoming Major Players in Cell-Cell Communication in Bacteria

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199174 Year: Pages: 122 DOI: 10.3389/978-2-88919-917-4 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Biology
Added to DOAB on : 2016-01-19 14:05:46
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The most common quorum sensing (QS) system in Gram-negative bacteria occurs via N-acyl homoserine lactone (AHLs) signals. An archetypical system consists of a LuxI-family protein synthesizing the AHL signal which binds at quorum concentrations to the cognate LuxR-family transcription factors which then control gene expression by binding to specific sequences in target gene promoters. QS LuxR-family proteins are approximately 250 amino acids long and made up of two domains; at the N-terminus there is an autoinducer-binding domain whereas the C-terminus contains a DNA-binding helix-turn-helix (HTH) domain. QS LuxRs display surprisingly low similarities (18-25%) even if they respond to structurally similar AHLs. 95% of LuxRs share 9 highly conserved amino acid residues; six of these are hydrophobic or aromatic and form the cavity of the AHL-binding domain and the remaining three are in the HTH domain. With only very few exceptions, the luxI/R cognate genes of AHL QS systems are located adjacent to each other. The sequencing of many bacterial genomes has revealed that many proteobacteria also possess LuxRs that do not have a cognate LuxI protein associated with them. These LuxRs have been called orphans and more recently solos. LuxR solos are widespread in proteobacterial species that possess a canonical complete AHL QS system as well as in species that do not. In many cases more than one LuxR solo is present in a bacterial genome. Scientists are beginning to investigate these solos. Are solos responding to AHL signals? If present in a bacterium which possesses a canonical AHL QS system are solos an integral part of the regulatory circuit? Are LuxR solos eavesdropping on AHLs produced by neighboring bacteria? Have they evolved to respond to different signals instead of AHLs, and are these signals endogenously produced or exogenously provided? Are they involved in interkingdom signaling by responding to eukaryotic signals? Recent studies have revealed that LuxR solos are involved in several mechanisms of cell-cell communication in bacteria implicating them in bacterial intraspecies and interspecies communication as well as in interkingdom signaling by responding to molecules produced by eukaryotes. LuxR solos are likely to become major players in signaling since they are widespread among proteobacterial genomes and because initial studies highlight their different roles in bacterial communication. This Research Topic allows scientists studying or interested in LuxR solos to report their data and/or express their hypotheses and thoughts on this important and currently understudied family of signaling proteins.

Keywords

AHL --- LuxR solos --- Quorum Sensing --- signaling --- Bacteria

Molecular Pathways of Estrogen Receptor Action

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ISBN: 9783038972969 9783038972976 Year: Pages: 304 DOI: 10.3390/books978-3-03897-297-6 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Biology
Added to DOAB on : 2018-10-22 10:23:01
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ca. 200 words; this text will present the book in all promotional forms (e.g. flyers). Please describe the book in straightforward and consumer-friendly terms.[Estrogen receptors (ERs) are typical members of the superfamily of nuclear receptors that mainly function as ligand-inducible transcription factors that bind chromatin, as homodimers, at specific response elements. A tight reciprocal coupling between rapid ‘non-genomic’ and ‘genomic’ ER actions may also occur in many physiological processes. ERs have long been evaluated for their roles in controlling the expression of genes involved in vital cellular processes such as proliferation, apoptosis, and differentiation. Therefore, given the various and pleiotropic functions of ERs, the dysregulation of their pathways contributes to several diseases such as the hormone-dependent breast; endometrial and ovarian cancers; and neurodegenerative diseases, cardiovascular diseases, and osteoporosis. In this printed edition of the Special Issue, “Molecular Pathways of Estrogen Receptor Action”, promising results on understanding the mechanisms underlying ER-mediated effects in various pathophysiological processes are represented, covering different roles of ER pathways in the tumorigenesis, the resistance to endocrine therapy, the dynamics of 3D genome organization, and cross-talk with other signaling pathways. This Special Issue also provides insight into the emerging roles of estrogen-signaling pathways in lung cancer, the tumor microenvironment, and the immune system.]

Ethylene: A Key Regulatory Molecule in Plants

Authors: --- --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453412 Year: Pages: 310 DOI: 10.3389/978-2-88945-341-2 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Botany --- Physiology
Added to DOAB on : 2018-11-22 11:28:10
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Ethylene is a simple gaseous phytohormone with multiple roles in regulation of metabolism at cellular, molecular, and whole plant level. It influences performance of plants under optimal and stressful environments by interacting with other signaling molecules. Understanding the ethylene biosynthesis and action through the plant’s life can contribute to improve the knowledge of plant functionality and use of this plant hormone may drive adaptation and defense of plants from the adverse environmental conditions. The action of ethylene depends on its concentration in cell and the sensitivity of plants to the hormone. In recent years, research on ethylene has been focused, due to its dual action, on the regulation of plant processes at physiological and molecular level. The involvement of ethylene in the regulation of transcription needs to be widely explored involving the interaction with other key molecular regulators. The aim of the current research topic was to explore and update our understanding on its regulatory role in plant developmental mechanisms at cellular or whole plant level under optimal and changing environmental conditions. The present edited volume includes original research papers and review articles describing ethylene’s regulatory role in plant development during plant ontogeny and also explains how it interacts with biotic and abiotic stress factors. This comprehensive collection of researches provide evidence that ethylene is essential in different physiological processes and does not always work alone, but in coordinated manner with other plant hormones. This research topic is also a source of tips for further works that should be addressed for the biology and molecular effects on plants.

Advanced Signaling Support for IP-based Networks

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ISBN: 9783731500377 Year: Pages: XXX, 333 p. DOI: 10.5445/KSP/1000035118 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Computer Science
Added to DOAB on : 2019-07-30 20:02:01
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This work develops a set of advanced signaling concepts for IP-based networks. It proposes a design for secure and authentic signaling and provides QoS signaling support for mobile users. Furthermore, this work develops methods which allow for scalable QoS signaling by realizing QoS-based group communication mechanisms and through aggregation of resource reservations.

Towards a molecular classification of colorectal cancer

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195671 Year: Pages: 62 DOI: 10.3389/978-2-88919-567-1 Language: English
Publisher: Frontiers Media SA
Subject: Oncology --- Medicine (General)
Added to DOAB on : 2016-02-05 17:24:33
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In 2007, Jeremy Jass proposed a molecular classification of colorectal cancer including KRAS, BRAF, Mismatch Repair, CIMP and MGMT Status. Since then, many prognostic and predictive studies have been published on this topic, mainly focusing on one single molecular marker. The aim of the e-book is to summarize the knowledge in 2014 from a multidisciplinary point of view that can potentially be used as a manual by CRC researchers in every field.

Cell Signaling in Host-Pathogen Interactions: The Host Point of View

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889454556 Year: Pages: 414 DOI: 10.3389/978-2-88945-455-6 Language: English
Publisher: Frontiers Media SA
Subject: Medicine (General) --- Allergy and Immunology --- Science (General) --- Microbiology
Added to DOAB on : 2018-11-16 17:17:57
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The ability of pathogens, such as parasites, bacteria, fungi and viruses to invade, persist and adapt in both invertebrate and vertebrate hosts is multifactorial and depends on both pathogen and host fitness. Communication between a pathogen and its host relies on a wide and dynamic array of molecular interactions. Through this constant communication most pathogens evolved to be relatively benign, whereas killing of its host by a pathogen represents a failure to adapt. Pathogens are lethal to their host when their interaction has not been long enough for adaptation. Evolution has selected conserved immune receptors that recognize signature patterns of pathogens as non-self elements and initiate host innate responses aimed at eradicating infection. Conversely, pathogens evolved mechanisms to evade immune recognition and subvert cytokine secretion in order to survive, replicate and cause disease. The cell signaling machinery is a critical component of the immune system that relays information from the receptors to the nucleus where transcription of key immune genes is activated. Host cells have developed signal transduction systems to maintain homeostasis with pathogens. Most cellular processes and cell signaling pathways are tightly regulated by protein phosphorylation in which protein kinases are key protagonists. Pathogens have developed multiple mechanisms to subvert important signal transduction pathways such as the mitogen activated protein kinase (MAPK) and the nuclear factor kB (NF-kB) pathways. Pathogens also secrete effectors that manipulate actin cytoskeleton and its regulators, hijack cell cycle machinery and alter vesicular trafficking. This research topic focuses on the cellular signaling mechanisms that are essential for host immunity and their subversion by pathogens.

Thiol-based redox homeostasis and signalling

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889192847 Year: Pages: 235 DOI: 10.3389/978-2-88919-284-7 Language: English
Publisher: Frontiers Media SA
Subject: Botany --- Physiology --- Science (General)
Added to DOAB on : 2015-12-10 11:59:07
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In contrast to the situation in heterotrophic organisms, plant genomes code for a significantly larger number of oxidoreductases such as thioredoxins (TRXs) and glutaredoxins (GRXs). These proteins provide a biochemical mechanism that allows the rapid and reversible activation or deactivation of protein functions in response to changing environmental conditions, as oxidative conditions caused by excessive photosynthesis. Indeed, owing to the fact that cysteines are sensitive to oxidation, TRXs and GRXs play an essential role in controlling the redox state of protein thiol groups. These redox-dependent post-translational modifications have proven to be critical for many cellular functions constituting regulatory, signalling or protective mechanisms. The articles contained in this Research Topic provide timely overviews and new insights into thiol-dependent redox regulation mechanisms with a focus on TRX- and GRX-based reduction systems in plants. The different contexts discussed take into account physiological, developmental and environmental conditions.

Essential Pathways and Circuits of Autism Pathogenesis

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199051 Year: Pages: 181 DOI: 10.3389/978-2-88919-905-1 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology --- Genetics
Added to DOAB on : 2016-01-19 14:05:46
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The Centers for Disease Control and Prevention estimate that 1 in 68 children in the United states is afflicted with autism spectrum disorders (ASD), yet at this time, there is no cure for the disease. Autism is characterized by delays in the development of many basic skills, most notably the ability to socialize and adapt to novelty. The condition is typically identified in children around 3 years of age, however the high heritability of autism suggests that the disease process begins at conception. The identification of over 500 ASD risk genes, has enabled the molecular genetic dissection of the pathogenesis of the disease in model organisms such as mice. Despite the genetic heterogeneity of ASD etiology, converging evidence suggests that these disparate genetic lesions may result in the disruption of a limited number of key biochemical pathways or circuits. Classification of patients into groups by pathogenic rather than etiological categories, will likely aid future therapeutic development and clinical trials. In this set of papers, we explore the existing evidence supporting this view. Specifically, we focus on biochemical cascades such as mTOR and ERK signaling, the mRNA network bound by FMRP and UBE3A, dorsal and ventral striatal circuits, cerebellar circuits, hypothalamic projections, as well as prefrontal and anterior cingulate cortical circuits. Special attention will be given to studies that demonstrate the necessity and/or sufficiency of genetic disruptions (e.g. by molecular deletion and/or replacement) in these pathways and circuits for producing characteristic behavioral features of autism. Necessarily these papers will be heavily weighted towards basic mechanisms elucidated in animal models, but may also include investigations in patients.

Lipid Signalling In Plant Development And Responses To Environmental Stresses

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199105 Year: Pages: 112 DOI: 10.3389/978-2-88919-910-5 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Botany
Added to DOAB on : 2016-01-19 14:05:46
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In response to environmental stresses, or during development, plant cells will produce lipids that will act as intracellular or intercellular mediators. Glycerophospholipid and/or sphingolipid second messengers resulting from the action of lipid metabolizing enzymes (e.g. lipid-kinases or lipases) are commonly found within cells. The importance of such mediating lipids in plants has become increasingly apparent. Responses to biotic and abiotic stresses, and to plant hormones, all appear to involve and require lipid signals. Likewise, developmental processes, in particular polarized growth, seem also to involve signalling lipids. Amongst these lipids, phosphatidic acid (PA) has received the most attention. It can be produced by phospholipases D, but also by diacylglycerol kinases coupled to phospholipases C. Proteins that bind phosphatidic acid, and for which the activity is altered upon binding, have been identified. Furthermore, other lipids are also important in signalling processes. PA can be phosphorylated into diacylglycerol-pyrophosphate, and plants are one of the first biological models where the production of this lipid has been reported, and its implication in signal transduction have been demonstrated. PA can also be deacylated into lyso- phosphatidic acid. The phosphorylated phosphatidylinositols, i.e. the phosphoinositides, can act as substrate of phospholipases C, but are also mediating lipids per se, since proteins that bind them have been identified. Other important lipid mediators belong to the sphingolipid family such the phosphorylated phytosphingosine, or long-chain bases. Many questions remain unanswered concerning lipid signalling in plants. Understanding and discussing current knowledge on these mechanisms will provide insights into plant mechanisms in response to constraints, either developmental or environmental.

A dynamic interplay between membranes and the cytoskeleton critical for cell development and signaling

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889193233 Year: Pages: 80 DOI: 10.3389/978-2-88919-323-3 Language: English
Publisher: Frontiers Media SA
Subject: Botany --- Science (General)
Added to DOAB on : 2016-02-05 17:24:33
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Various cellular processes underlying plant development and response to environmental cues rely on a dynamic interplay between membranes and the cytoskeleton, e.g. vesicle and organelle trafficking, endocytosis, exocytosis, and signal transduction. In recent years, significant progress in the understanding of such interplay has been achieved and several critical links between membranes and the cytoskeleton have been characterized. As an example, recent work has clarified how auxin promotes the reorganization of cortical actin filaments by the activation of Rho GTPase pathways, and how such reorganization in turn locally modifies endocytosis and/or exocytosis and directs asymmetric distribution of PIN family of auxin transporters. Another recent achievement is the characterization of the Rho- and microtubule-driven mechanism by which the cell wall architecture is established. In particular, the elegant work by Oda and Fukuda (Science 337 p.1333, 2012) provides evidence that secondary wall patterning in xylem vessel primarily relies on two processes: a local activation of the plant Rho GTPase ROP11 and a mutual, MIDD1-mediated, inhibitory interaction between active ROP domains and cortical microtubules. Additional examples include recent genetic evidence that microtubule and actin filament interacting/regulatory proteins, such as MAP65-1 and capping protein, function as transducers of membrane lipid signaling into changes in cytoskeleton dynamics and organization. This Research Topic aims at collecting a comprehensive set of articles dealing with cellular processes involving membrane-cytoskeleton interactions. Its scope extends beyond the specific fields defined by the above examples and includes intracellular trafficking, host-pathogen interactions, response to biotic and abiotic stresses and hormonal regulation of growth. We hope that this Research Topic will also highlight critical questions that need to be addressed in the future. We welcomed Original Research Articles, Technical/Methodological Advances (e.g. analysis of cytoskeleton dynamics close to membranes), Reviews and Mini Reviews that can expand our understanding of how and why membranes and the cytoskeleton interact.

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