Showing papers on "Signal transduction published in 2013"
TL;DR: An overview of the most relevant modes of crosstalk and cooperativity between NF-κB and other signaling molecules during inflammation and cancer is provided.
Abstract: The NF-κB family of transcription factors has an essential role in inflammation and innate immunity. Furthermore, NF-κB is increasingly recognized as a crucial player in many steps of cancer initiation and progression. During these latter processes NF-κB cooperates with multiple other signaling molecules and pathways. Prominent nodes of crosstalk are mediated by other transcription factors such as STAT3 and p53 or the ETS related gene ERG. These transcription factors either directly interact with NF-κB subunits or affect NF-κB target genes. Crosstalk can also occur through different kinases, such as GSK3-β, p38, or PI3K, which modulate NF-κB transcriptional activity or affect upstream signaling pathways. Other classes of molecules that act as nodes of crosstalk are reactive oxygen species and miRNAs. In this review, we provide an overview of the most relevant modes of crosstalk and cooperativity between NF-κB and other signaling molecules during inflammation and cancer.
2,404 citations
TL;DR: The mechanisms through which T cell activation, differentiation and function is controlled by co-stimulatory and co-inhibitory receptors are reviewed.
Abstract: Co-stimulatory and co-inhibitory receptors have a pivotal role in T cell biology, as they determine the functional outcome of T cell receptor (TCR) signalling. The classic definition of T cell co-stimulation continues to evolve through the identification of new co-stimulatory and co-inhibitory receptors, the biochemical characterization of their downstream signalling events and the delineation of their immunological functions. Notably, it has been recently appreciated that co-stimulatory and co-inhibitory receptors display great diversity in expression, structure and function, and that their functions are largely context dependent. Here, we focus on some of these emerging concepts and review the mechanisms through which T cell activation, differentiation and function is controlled by co-stimulatory and co-inhibitory receptors.
2,378 citations
TL;DR: Dysregulation of caspases underlies human diseases including cancer and inflammatory disorders, and major efforts to design better therapies for these diseases seek to understand how these enzymes work and how they can be controlled.
Abstract: Caspases are a family of endoproteases that provide critical links in cell regulatory networks controlling inflammation and cell death. The activation of these enzymes is tightly controlled by their production as inactive zymogens that gain catalytic activity following signaling events promoting their aggregation into dimers or macromolecular complexes. Activation of apoptotic caspases results in inactivation or activation of substrates, and the generation of a cascade of signaling events permitting the controlled demolition of cellular components. Activation of inflammatory caspases results in the production of active proinflammatory cytokines and the promotion of innate immune responses to various internal and external insults. Dysregulation of caspases underlies human diseases including cancer and inflammatory disorders, and major efforts to design better therapies for these diseases seek to understand how these enzymes work and how they can be controlled.
2,127 citations
TL;DR: Recent advances in understanding the diversity of molecular mechanisms that govern ER stress signaling in health and disease are summarized.
1,605 citations
TL;DR: This review highlights key advances in understanding PPARγ signaling in energy homeostasis and metabolic disease and also provides new explanations for adverse events linked to TZD-based therapy.
Abstract: Thiazolidinediones (TZDs) are potent insulin sensitizers that act through the nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ) and are highly effective oral medications for type 2 diabetes. However, their unique benefits are shadowed by the risk for fluid retention, weight gain, bone loss and congestive heart failure. This raises the question as to whether it is possible to build a safer generation of PPARγ-specific drugs that evoke fewer side effects while preserving insulin-sensitizing potential. Recent studies that have supported the continuing physiologic and therapeutic relevance of the PPARγ pathway also provide opportunities to develop newer classes of molecules that reduce or eliminate adverse effects. This review highlights key advances in understanding PPARγ signaling in energy homeostasis and metabolic disease and also provides new explanations for adverse events linked to TZD-based therapy.
1,460 citations
TL;DR: This Review discusses the current knowledge about the regulation and the function of MAPKs in innate immunity, as well as the importance of negative feedback loops in limiting MAPK activity to prevent host tissue damage and how pathogens have evolved complex mechanisms to manipulate MAPK activation to increase their virulence.
Abstract: Following pathogen infection or tissue damage, the stimulation of pattern recognition receptors on the cell surface and in the cytoplasm of innate immune cells activates members of each of the major mitogen-activated protein kinase (MAPK) subfamilies--the extracellular signal-regulated kinase (ERK), p38 and Jun N-terminal kinase (JNK) subfamilies. In conjunction with the activation of nuclear factor-κB and interferon-regulatory factor transcription factors, MAPK activation induces the expression of multiple genes that together regulate the inflammatory response. In this Review, we discuss our current knowledge about the regulation and the function of MAPKs in innate immunity, as well as the importance of negative feedback loops in limiting MAPK activity to prevent host tissue damage. We also examine how pathogens have evolved complex mechanisms to manipulate MAPK activation to increase their virulence. Finally, we consider the potential of the pharmacological targeting of MAPK pathways to treat autoimmune and inflammatory diseases.
1,285 citations
TL;DR: Evidence suggests that ATM-mediated phosphorylation has a role in the response to other types of genotoxic stress and it has become apparent that ATM is active in other cell signalling pathways involved in maintaining cellular homeostasis.
Abstract: The protein kinase ataxia-telangiectasia mutated (ATM) is best known for its role as an apical activator of the DNA damage response in the face of DNA double-strand breaks (DSBs). Following induction of DSBs, ATM mobilizes one of the most extensive signalling networks that responds to specific stimuli and modifies directly or indirectly a broad range of targets. Although most ATM research has focused on this function, evidence suggests that ATM-mediated phosphorylation has a role in the response to other types of genotoxic stress. Moreover, it has become apparent that ATM is active in other cell signalling pathways involved in maintaining cellular homeostasis.
1,281 citations
TL;DR: This review focuses on the design ofCARs, including the requirements for optimal antigen recognition and different modalities to provide costimulatory support to targeted T cells, which include the use of second- and third generation CARs, costimulation ligands, chimericcostimulatory receptors, and cytokines.
Abstract: Chimeric antigen receptors (CAR) are recombinant receptors that provide both antigen-binding and T-cell–activating functions. A multitude of CARs has been reported over the past decade, targeting an array of cell surface tumor antigens. Their biologic functions have dramatically changed following the introduction of tripartite receptors comprising a costimulatory domain, termed second-generation CARs. These have recently shown clinical benefit in patients treated with CD19-targeted autologous T cells. CARs may be combined with costimulatory ligands, chimeric costimulatory receptors, or cytokines to further enhance T-cell potency, specificity, and safety. CARs represent a new class of drugs with exciting potential for cancer immunotherapy.
Significance: CARs are a new class of drugs with great potential for cancer immunotherapy. Upon their expression in T lymphocytes, CARs direct potent, targeted immune responses that have recently shown encouraging clinical outcomes in a subset of patients with B-cell malignancies. This review focuses on the design of CARs, including the requirements for optimal antigen recognition and different modalities to provide costimulatory support to targeted T cells, which include the use of second- and third-generation CARs, costimulatory ligands, chimeric costimulatory receptors, and cytokines. Cancer Discov; 3(4); 388–98. ©2013 AACR.
1,170 citations
TL;DR: This work focuses on thyroid cancer, where the elucidation of the fundamental role of several major signalling pathways and related molecular derangements and central to these mechanisms are mutation, gene copy-number gain and aberrant gene methylation.
Abstract: Thyroid cancer is a common endocrine malignancy. There has been exciting progress in understanding its molecular pathogenesis in recent years, as best exemplified by the elucidation of the fundamental role of several major signalling pathways and related molecular derangements. Central to these mechanisms are the genetic and epigenetic alterations in these pathways, such as mutation, gene copy-number gain and aberrant gene methylation. Many of these molecular alterations represent novel diagnostic and prognostic molecular markers and therapeutic targets for thyroid cancer, which provide unprecedented opportunities for further research and clinical development of novel treatment strategies for this cancer.
1,119 citations
TL;DR: Regulatory mechanisms of the Hippo pathway are reviewed and potential implications involved in different physiological and pathological conditions are discussed.
Abstract: Control of cell number is crucial in animal development and tissue homeostasis, and its dysregulation may result in tumor formation or organ degeneration. The Hippo pathway in both Drosophila and mammals regulates cell number by modulating cell proliferation, cell death, and cell differentiation. Recently, numerous upstream components involved in the Hippo pathway have been identified, such as cell polarity, mechanotransduction, and G-protein-coupled receptor (GPCR) signaling. Actin cytoskeleton or cellular tension appears to be the master mediator that integrates and transmits upstream signals to the core Hippo signaling cascade. Here, we review regulatory mechanisms of the Hippo pathway and discuss potential implications involved in different physiological and pathological conditions.
1,049 citations
TL;DR: The studies suggest that Nrf2 contributes to both intrinsic and acquired chemoresistance, and the challenges in the development of NRF2-based drugs for chemoprevention and chemotherapy are outlined.
Abstract: The Nrf2 (nuclear factor erythroid 2 [NF-E2]-related factor 2 [Nrf2])-Keap1 (Kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein 1) signaling pathway is one of the most important cell defense and survival pathways. Nrf2 can protect cells and tissues from a variety of toxicants and carcinogens by increasing the expression of a number of cytoprotective genes. As a result, several Nrf2 activators are currently being tested as chemopreventive compounds in clinical trials. Just as Nrf2 protects normal cells, studies have shown that Nrf2 may also protect cancer cells from chemotherapeutic agents and facilitate cancer progression. Nrf2 is aberrantly accumulated in many types of cancer, and its expression is associated with a poor prognosis in patients. In addition, Nrf2 expression is induced during the course of drug resistance. Collectively, these studies suggest that Nrf2 contributes to both intrinsic and acquired chemoresistance. This discovery has opened up a broad spectrum of research geared toward a better understanding of the role of Nrf2 in cancer. This review provides an overview of (1) the Nrf2-Keap1 signaling pathway, (2) the dual role of Nrf2 in cancer, (3) the molecular basis of Nrf2 activation in cancer cells, and (4) the challenges in the development of Nrf2-based drugs for chemoprevention and chemotherapy.
TL;DR: Inhibitory receptors for major histocompatibility complex class I (MHC-I) have a critical role in controlling NK cell responses and, paradoxically, in maintaining NK cells in a state of responsiveness to subsequent activation events, a process referred to as licensing.
Abstract: Understanding how signals are integrated to control natural killer (NK) cell responsiveness in the absence of antigen-specific receptors has been a challenge, but recent work has revealed some underlying principles that govern NK cell responses. NK cells use an array of innate receptors to sense their environment and respond to alterations caused by infections, cellular stress, and transformation. No single activation receptor dominates; instead, synergistic signals from combinations of receptors are integrated to activate natural cytotoxicity and cytokine production. Inhibitory receptors for major histocompatibility complex class I (MHC-I) have a critical role in controlling NK cell responses and, paradoxically, in maintaining NK cells in a state of responsiveness to subsequent activation events, a process referred to as licensing. MHC-I-specific inhibitory receptors both block activation signals and trigger signals to phosphorylate and inactivate the small adaptor Crk. These different facets of inhibito...
TL;DR: The interplay between tissue mechanics and biochemical signaling orchestrates tissue morphogenesis and patterning in development.
TL;DR: It is found that Olfr78, an olfactory receptor expressed in the kidney, responds to short chain fatty acids (SCFAs), and SCFAs produced by the gut microbiota modulate blood pressure via OlfR78 and Gpr41.
Abstract: Olfactory receptors are G protein-coupled receptors that mediate olfactory chemosensation and serve as chemosensors in other tissues. We find that Olfr78, an olfactory receptor expressed in the kidney, responds to short chain fatty acids (SCFAs). Olfr78 is expressed in the renal juxtaglomerular apparatus, where it mediates renin secretion in response to SCFAs. In addition, both Olfr78 and G protein-coupled receptor 41 (Gpr41), another SCFA receptor, are expressed in smooth muscle cells of small resistance vessels. Propionate, a SCFA shown to induce vasodilation ex vivo, produces an acute hypotensive response in wild-type mice. This effect is differentially modulated by disruption of Olfr78 and Gpr41 expression. SCFAs are end products of fermentation by the gut microbiota and are absorbed into the circulation. Antibiotic treatment reduces the biomass of the gut microbiota and elevates blood pressure in Olfr78 knockout mice. We conclude that SCFAs produced by the gut microbiota modulate blood pressure via Olfr78 and Gpr41.
TL;DR: This Review focuses on ceramide signalling and the targeting of specific metabolic junctures to amplify the tumour suppressive activities of ceramide.
Abstract: One crucial barrier to progress in the treatment of cancer has been the inability to control the balance between cell proliferation and apoptosis: enter ceramide. Discoveries over the past 15 years have elevated this sphingolipid to the lofty position of a regulator of cell fate. Ceramide, it turns out, is a powerful tumour suppressor, potentiating signalling events that drive apoptosis, autophagic responses and cell cycle arrest. However, defects in ceramide generation and metabolism in cancer cells contribute to tumour cell survival and resistance to chemotherapy. This Review focuses on ceramide signalling and the targeting of specific metabolic junctures to amplify the tumour suppressive activities of ceramide. The potential of ceramide-based therapeutics in the treatment of cancer is also discussed.
TL;DR: A better understanding of how astrocytes regulate neural circuit development and function in the healthy and diseased brain might lead to the development of therapeutic agents to treat these diseases.
Abstract: Astrocytes are now emerging as key participants in many aspects of brain development, function and disease. In particular, new evidence shows that astrocytes powerfully control the formation, maturation, function and elimination of synapses through various secreted and contact-mediated signals. Astrocytes are also increasingly being implicated in the pathophysiology of many psychiatric and neurological disorders that result from synaptic defects. A better understanding of how astrocytes regulate neural circuit development and function in the healthy and diseased brain might lead to the development of therapeutic agents to treat these diseases.
TL;DR: The ability of proline to influence disparate cellular outcomes may be governed by ROS levels generated in the mitochondria, and defining the threshold at which proline metabolic enzyme expression switches from inducing survival pathways to cellular apoptosis would provide molecular insights into cellular redox regulation by proline.
Abstract: Significance: The imino acid proline is utilized by different organisms to offset cellular imbalances caused by environmental stress. The wide use in nature of proline as a stress adaptor molecule indicates that proline has a fundamental biological role in stress response. Understanding the mechanisms by which proline enhances abiotic/biotic stress response will facilitate agricultural crop research and improve human health. Recent Advances: It is now recognized that proline metabolism propels cellular signaling processes that promote cellular apoptosis or survival. Studies have shown that proline metabolism influences signaling pathways by increasing reactive oxygen species (ROS) formation in the mitochondria via the electron transport chain. Enhanced ROS production due to proline metabolism has been implicated in the hypersensitive response in plants, lifespan extension in worms, and apoptosis, tumor suppression, and cell survival in animals. Critical Issues: The ability of proline to influence...
TL;DR: The results support a model whereby calcium-dependent TSLP release by keratinocytes activates both primary afferent neurons and immune cells to promote inflammatory responses in the skin and airways.
TL;DR: Although these structures only provide snapshots of isolated processes, an emerging picture is that these signaling cascades coalesce into large oligomeric signaling complexes, or signalosomes, for signal propagation.
Abstract: NF-κB (nuclear factor kappa B) family transcription factors are master regulators of immune and inflammatory processes in response to both injury and infection. In the latent state, NF-κBs are sequestered in the cytosol by their inhibitor IκB (inhibitor of NF-κB) proteins. Upon stimulations of innate immune receptors such as Toll-like receptors and cytokine receptors such as those in the TNF (tumor necrosis factor) receptor superfamily, a series of membrane proximal events lead to the activation of the IKK (IκB kinase). Phosphorylation of IκBs results in their proteasomal degradation and the release of NF-κB for nuclear translocation and activation of gene transcription. Here, we review the plethora of structural studies in these NF-κB activation pathways, including the TRAF (TNF receptor–associated factor) proteins, IKK, NF-κB, ubiquitin ligases, and deubiquitinating enzymes. Although these structures only provide snapshots of isolated processes, an emerging picture is that these signaling cascades coale...
TL;DR: In this article, the authors discuss the origin and molecular properties of the glucocorticoid receptor (GR) isoforms and their contribution to the specificity and sensitivity of glucoc corticoid signaling in healthy and diseased tissues.
Abstract: Glucocorticoids are primary stress hormones necessary for life that regulate numerous physiologic processes in an effort to maintain homeostasis. Synthetic derivatives of these hormones have been mainstays in the clinic for treating inflammatory diseases, autoimmune disorders, and hematologic cancers. The physiologic and pharmacologic actions of glucocorticoids are mediated by the glucocorticoid receptor (GR), a member of the nuclear receptor superfamily of ligand-dependent transcription factors. Ligand-occupied GR induces or represses the transcription of thousands of genes through direct binding to DNA response elements, physically associating with other transcription factors, or both. The traditional view that glucocorticoids act through a single GR protein has changed dramatically with the discovery of a large cohort of receptor isoforms with unique expression, gene-regulatory, and functional profiles. These GR subtypes are derived from a single gene by means of alternative splicing and alternative translation initiation mechanisms. Posttranslational modification of these GR isoforms further expands the diversity of glucocorticoid responses. Here we discuss the origin and molecular properties of the GR isoforms and their contribution to the specificity and sensitivity of glucocorticoid signaling in healthy and diseased tissues.
TL;DR: Two small molecule RIP3 kinase inhibitors are described and employ them to demonstrate the common requirement for RIP3 Kinase in programmed necrosis induced by RIP1-RIP3, DAI- RIP3, and TRIF-RIP 3 complexes.
TL;DR: It is shown that the adrenergic agonist isoprenaline promotes receptor and G protein activation in the plasma membrane as expected, but also in the early endosome membrane, and that internalized receptors contribute to the overall cellular cyclic AMP response within several minutes after agonist application, providing direct support for the hypothesis that canonical GPCR signalling occurs from endosomes as well as the plasma membranes.
Abstract: Conformation-specific antibodies capable of monitoring the activation state of a G-protein-coupled seven-transmembrane receptor, the β2-adrenoceptor, reveals receptor and G-protein activation not only in the plasma membrane, but also in the endosome. It is widely assumed that G-protein-linked signalling occurs only at the plasma membrane. In this study, Mark von Zastrow and colleagues use conformation-specific single-chain antibodies to directly probe the activation of the β2-adrenoceptor, which is a prototypical G-protein-coupled receptor, and its cognate G protein, Gs, in living cells. They show that classical or canonical G-protein-linked signalling occurs from endosomes as well as from the plasma membrane. A long-held tenet of molecular pharmacology is that canonical signal transduction mediated by G-protein-coupled receptor (GPCR) coupling to heterotrimeric G proteins is confined to the plasma membrane. Evidence supporting this traditional view is based on analytical methods that provide limited or no subcellular resolution1. It has been subsequently proposed that signalling by internalized GPCRs is restricted to G-protein-independent mechanisms such as scaffolding by arrestins2,3, or GPCR activation elicits a discrete form of persistent G protein signalling4,5,6,7,8,9, or that internalized GPCRs can indeed contribute to the acute G-protein-mediated response10. Evidence supporting these various latter hypotheses is indirect or subject to alternative interpretation, and it remains unknown if endosome-localized GPCRs are even present in an active form. Here we describe the application of conformation-specific single-domain antibodies (nanobodies) to directly probe activation of the β2-adrenoceptor, a prototypical GPCR11, and its cognate G protein, Gs (ref. 12), in living mammalian cells. We show that the adrenergic agonist isoprenaline promotes receptor and G protein activation in the plasma membrane as expected, but also in the early endosome membrane, and that internalized receptors contribute to the overall cellular cyclic AMP response within several minutes after agonist application. These findings provide direct support for the hypothesis that canonical GPCR signalling occurs from endosomes as well as the plasma membrane, and suggest a versatile strategy for probing dynamic conformational change in vivo.
TL;DR: Recent advances in the molecular understanding of cytosolic nucleic acid detection and its evasion by viruses are detailed.
TL;DR: GPR41 and GPR43 mice had reduced inflammatory responses after administration of ethanol or TNBS compared with control mice, and had a slower immune response against C rodentium infection, clearing the bacteria more slowly.
TL;DR: NMR spectroscopy is used to characterize the conformational dynamics of the transmembrane core of the β(2)-adrenergic receptor (β(2)AR), a prototypical GPCR, and shows that for β( 2)AR, unlike rhodopsin, an agonist alone does not stabilize a fully active conformation.
TL;DR: The differentiation plasticity of epithelial cells that mediates TGF-&bgr;-induced EMT and reversion from mesenchymal to epithelial phenotype are increasingly seen as integral aspects of cancer progression that contribute to survival and dissemination of cancer cells.
Abstract: Purpose of reviewTGF-β acts as a potent driver of cancer progression through the induction of epithelial–mesenchymal transition (EMT), in which epithelial cells acquire mesenchymal phenotype, leading to enhanced motility and invasion. Recent reports highlight the fundamental roles of TGF-β-induced E
TL;DR: The molecular mechanisms of the antagonistic signaling between NF-κB and SIRT1 are examined and how this crosstalk controls inflammatory process and energy metabolism is described to induce the appearance of chronic inflammation in metabolic diseases.
TL;DR: By understanding how tumor-initiating cells such as CSCs escape chemotherapy, more informed approaches to treating cancer will develop and may improve clinical outcomes for cancer patients, this review describes a number of mechanisms of chemoresistance in cancer stem cells.
Abstract: Chemotherapy is one of the standard methods of treatment in many cancers. While chemotherapy is often capable of inducing cell death in tumors and reducing the tumor bulk, many cancer patients experience recurrence and ultimately death because of treatment failure. In recent years, cancer stem cells (CSCs) have gained intense interest as key tumor-initiating cells that may also play an integral role in recurrence following chemotherapy. As such, a number of mechanisms of chemoresistance have been identified in CSCs. In this review, we describe a number of these mechanisms of chemoresistance including ABC transporter expression, aldehyde dehydrogenase (ALDH) activity, B-cell lymphoma-2 (BCL2) related chemoresistance, enhanced DNA damage response and activation of key signaling pathways. Furthermore, we evaluate studies that demonstrate potential methods for overcoming chemoresistance and treating chemoresistant cancers that are driven by CSCs. By understanding how tumor-initiating cells such as CSCs escape chemotherapy, more informed approaches to treating cancer will develop and may improve clinical outcomes for cancer patients.
TL;DR: It is shown that EZH2 binds to and methylates STAT3, leading to enhanced STAT3 activity by increased tyrosine phosphorylation of STAT3.
TL;DR: An update on glucocorticoid receptor signaling is provided and the role of GR signaling in physiological and pathophysiological conditions in the major organ systems in the human body is highlighted.