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Maki Fukami, Erina Suzuki, Maki Igarashi, Mami Miyado, Tsutomu Ogata
The human genome encodes more than 700 G-protein coupled receptors (GPCRs), many of which are involved in hormone secretion. To date, more than 100 gain-of-function (activating) mutations in at least ten genes for GPCRs, in addition to several loss-of-function mutations, have been implicated in human endocrine disorders. Previously reported gain-of-function GPCR mutations comprise various missense substitutions, frameshift mutations, intragenic inframe deletions, and copy-number gains. Such mutations appear in both germline and somatic tumour cells, and lead to various hormonal abnormalities reflecting excessive receptor activity...
October 13, 2017: Clinical Endocrinology
Qing-Hong Zhang, Ji-Wei Hao, Guang-Lei Li, Xiao-Jing Ji, Xu-Dong Yao, Ning Dong, Yong-Ming Yao
OBJECTIVE: Glucagon-like peptide-1 (GLP-1)-based therapy via G protein-coupled receptor (GPCR) GLP-1R, to attenuate hyperglycemia in critical care has attracted great attention. However, the exaggerated inflammation by GLP-1R agonist, Exendin-4, in a mouse model of burn injury was quite unexpected. Recent studies found that GPCR might elicit proinflammatory effects by switching from Gαs to Gαi signaling in the immune system. Thus, we aimed to investigate the possible Gαs to Gαi switch in GLP-1R signaling in monocyte following burn injury...
October 11, 2017: Inflammation Research: Official Journal of the European Histamine Research Society ... [et Al.]
Simon R Foster, Hans Bräuner-Osborne
The ability to regulate the interaction between cells and their extracellular environment is essential for the maintenance of appropriate physiological function. For G protein-coupled receptors (GPCRs), this regulation occurs through multiple mechanisms that provide spatial and temporal control for signal transduction. One of the major mechanisms for GPCR regulation involves their endocytic trafficking, which serves to internalize the receptors from the plasma membrane and thereby attenuate G protein-dependent signaling...
October 11, 2017: Handbook of Experimental Pharmacology
Ronan Crepin, Gianluca Veggiani, Selma Djender, Anne Beugnet, François Planeix, Christophe Pichon, Sandrine Moutel, Sebastian Amigorena, Franck Perez, Nicolae Ghinea, Ario de Marco
Antibodies are essential reagents that are increasingly used in diagnostics and therapy. Their specificity and capacity to recognize their native antigen are critical characteristics for their in vivo application. Follicle-stimulating hormone receptor is a GPCR protein regulating ovarian follicular maturation and spermatogenesis. Recently, its potentiality as a cancer biomarker has been demonstrated but no antibody suitable for in vivo tumor targeting and treatment has been characterized so far. In this paper we describe the first successful attempt to recover recombinant antibodies against the FSHR and that: i) are directly panned from a pre-immune library using whole cells expressing the target receptor at their surface; ii) show inhibitory activity towards the FSH-induced cAMP accumulation; iii) do not share the same epitope with the natural binder FSH; iv) can be produced inexpensively as mono- or bivalent functional molecules in the bacterial cytoplasm...
October 7, 2017: Biochemical and Biophysical Research Communications
Yimei Wang, Li Jin, Ying Song, Mao Zhang, Dan Shan, Yuli Liu, Meng Fang, Fengxiang Lv, Rui-Ping Xiao, Yan Zhang
Aims: Ischemic heart disease is a leading cause of morbidity and mortality worldwide. Although timely restoration of coronary blood flow (reperfusion) is the most effective therapeutics of myocardial infarction, reperfusion causes further cardiac damage, i.e. ischemia-reperfusion (I/R) injury. β-arrestins (Arrbs) have been traditionally defined as negative regulators of G protein-coupled receptor (GPCR) signalling, but recent studies have shown that they are essential for G protein-independent, GPCR-mediated biased signalling...
August 4, 2017: Cardiovascular Research
Widad Dantoft, Pablo Martínez-Vicente, James Jafali, Lara Pérez-Martínez, Kim Martin, Konstantinos Kotzamanis, Marie Craigon, Manfred Auer, Neil T Young, Paul Walsh, Arnaud Marchant, Ana Angulo, Thorsten Forster, Peter Ghazal
Neonates and especially premature infants are highly susceptible to infection but still can have a remarkable resilience that is poorly understood. The view that neonates have an incomplete or deficient immune system is changing. Human neonatal studies are challenging, and elucidating host protective responses and underlying cognate pathway biology, in the context of viral infection in early life, remains to be fully explored. In both resource rich and poor settings, human cytomegalovirus (HCMV) is the most common cause of congenital infection...
2017: Frontiers in Immunology
Chih-Ta Henry Chien, Lukas R Helfinger, Mark J Bostock, Andras Solt, Yi Lei Tan, Daniel Nietlispach
Based on the saposin-A (SapA) scaffold protein we demonstrate the suitability of a size-adaptable phospholipid membrane-mimetic system for solution NMR studies of membrane proteins under close-to-native conditions. The Salipro nanoparticle size can be tuned over a wide pH range by adjusting the saposin-to-lipid stoichiometry enabling maintenance of sufficiently high amounts of phospholipid in the Salipro nanoparticle to mimic a realistic membrane environment while controlling the overall size to enable solution NMR for a range of membrane proteins...
October 9, 2017: Journal of the American Chemical Society
Parijat Sarkar, Amitabha Chattopadhyay
Solubilization of membrane proteins by amphiphilic detergents represents a crucial step in studies of membrane proteins in which proteins and lipids in natural membranes are dissociated giving rise to mixed clusters of proteins, lipids and detergents in the aqueous dispersion. Although solubilization is a popular method, physicochemical principles underlying solubilization are not well understood. In this work, we monitored solubilization of the bovine hippocampal serotonin1A receptor, a representative member of the GPCR family, using membrane dipole potential measured by a dual fluorescence ratiometric approach with a potential-sensitive fluorophore...
October 4, 2017: Chemistry and Physics of Lipids
Meng Zhou, Shuyu Guo, Lichan Yuan, Yuxin Zhang, Mengnan Zhang, Huimin Chen, Mengting Lu, Jianrong Yang, Junqing Ma
During tooth root development, stem cells from apical papillae (SCAPs) are indispensable, and their abilities of proliferation, migration and odontoblast differentiation are linked to root formation. Leucine-rich repeat-containing GPCR 4 (LGR4) modulates the biological processes of proliferation and differentiation in multiple stem cells. In this study, we showed that LGR4 is expressed in all odontoblast cell lineage cells and Hertwig's epithelial root sheath (HERS) during the mouse root formation in vivo. In vitro we determined that LGR4 is involved in the Wnt/β-catenin signaling pathway regulating proliferation and odonto/osteogenic differentiation of SCAPs...
October 6, 2017: Journal of Molecular Histology
Lindsay D Clark, Igor Dikiy, Karen Chapman, Karin E J Rödström, James Aramini, Michael V LeVine, George Khelashvili, Søren G F Rasmussen, Kevin H Gardner, Daniel M Rosenbaum
GPCRs regulate all aspects of human physiology, and biophysical studies have deepened our understanding of GPCR conformational regulation by different ligands. Yet there is no experimental evidence for how sidechain dynamics control allosteric transitions between GPCR conformations. To address this deficit, we generated samples of a wild-type GPCR (A2AR) that are deuterated apart from (1)H/(13)C NMR probes at isoleucine δ1 methyl groups, which facilitated (1)H/(13)C methyl TROSY NMR measurements with opposing ligands...
October 6, 2017: ELife
Johanna Breuer, Sebastian Herich, Tilman Schneider-Hohendorf, Achmet I Chasan, Nina Wettschureck, Catharina C Gross, Karin Loser, Alexander Zarbock, Johannes Roth, Luisa Klotz, Heinz Wiendl, Nicholas Schwab
OBJECTIVE: Dimethyl fumarate (DMF) is prescribed against relapsing-remitting multiple sclerosis (MS). Here, we investigated the effects of DMF and monomethyl fumarate (MMF), its metabolite in vivo, at the (inflamed) blood-brain barrier (BBB). METHODS: Effects of fumaric acid esters were analyzed using primary human brain-derived microvascular endothelial cells (HBMECs) in combination with peripheral blood mononuclear cells (PBMCs) derived from DMF-treated MS patients...
October 1, 2017: Multiple Sclerosis: Clinical and Laboratory Research
Sungsoo M Yoo, Richard A Cerione, Marc A Antonyak
Cool-associated tyrosine phosphorylated protein 1 (Cat1), also referred to as GPCR-kinase interacting protein 1 (Git1), is a ubiquitously expressed, multi-domain protein that is best known for regulating cell shape and migration. Cat1/Git1 functions as a GTPase activating protein (GAP) that inactivates certain members of the ADP-ribosylation factor (Arf) family of small GTPases. It is also a scaffold that brings together several signaling proteins at specific locations within the cell, ensuring their efficient activation...
October 5, 2017: Small GTPases
Garret R Anderson, Stephan Maxeiner, Richard Sando, Theodoros Tsetsenis, Robert C Malenka, Thomas C Südhof
Synapse assembly likely requires postsynaptic target recognition by incoming presynaptic afferents. Using newly generated conditional knock-in and knockout mice, we show in this study that latrophilin-2 (Lphn2), a cell-adhesion G protein-coupled receptor and presumptive α-latrotoxin receptor, controls the numbers of a specific subset of synapses in CA1-region hippocampal neurons, suggesting that Lphn2 acts as a synaptic target-recognition molecule. In cultured hippocampal neurons, Lphn2 maintained synapse numbers via a postsynaptic instead of a presynaptic mechanism, which was surprising given its presumptive role as an α-latrotoxin receptor...
September 28, 2017: Journal of Cell Biology
Elizabeth O Harrington, Alexander Vang, Julie Braza, Aparna Shil, Havovi Chichger
A hallmark of acute respiratory distress syndrome (ARDS) is pulmonary vascular permeability. In these settings, loss of barrier integrity is mediated by cell-contact disassembly and actin-remodelling. Studies into molecular mechanisms responsible for improving microvascular barrier function are therefore vital in the development of therapeutic targets for reducing vascular permeability in ARDS. The sweet taste receptor, T1R3 is a GPCR, activated following exposure to sweet molecules, to trigger a gustducin-dependent signal cascade...
September 28, 2017: American Journal of Physiology. Lung Cellular and Molecular Physiology
Yuichi Mazaki, Yasuhito Onodera, Tsunehito Higashi, Takahiro Horinouchi, Tsukasa Oikawa, Hisataka Sabe
BACKGROUND: The small GTPase ARF1 mediates membrane trafficking mostly from the Golgi, and is essential for the G protein-coupled receptor (GPCR)-mediated chemotaxis of neutrophils. In this process, ARF1 is activated by the guanine nucleotide exchanger GBF1, and is inactivated by the GTPase-activating protein GIT2. Neutrophils generate the Gβγ-PAK1-αPIX-GIT2 linear complex during GPCR-induced chemotaxis, in which αPIX activates RAC1/CDC42, which then employs PAK1. However, it has remained unclear as to why GIT2 is included in this complex...
October 2, 2017: Cell Communication and Signaling: CCS
Irini Topalidou, Kirsten Cooper, Laura Pereira, Michael Ailion
The NALCN/NCA ion channel is a cation channel related to voltage-gated sodium and calcium channels. NALCN has been reported to be a sodium leak channel with a conserved role in establishing neuronal resting membrane potential, but its precise cellular role and regulation are unclear. The Caenorhabditis elegans orthologs of NALCN, NCA-1 and NCA-2, act in premotor interneurons to regulate motor circuit activity that sustains locomotion. Recently we found that NCA-1 and NCA-2 are activated by a signal transduction pathway acting downstream of the heterotrimeric G protein Gq and the small GTPase Rho...
October 2017: PLoS Genetics
Ryan H Purcell, Randy A Hall
The adhesion G protein-coupled receptors (aGPCRs) are an evolutionarily ancient family of receptors that play key roles in many different physiological processes. These receptors are notable for their exceptionally long ectodomains, which span several hundred to several thousand amino acids and contain various adhesion-related domains, as well as a GPCR autoproteolysis-inducing (GAIN) domain. The GAIN domain is conserved throughout almost the entire family and undergoes autoproteolysis to cleave the receptors into two noncovalently-associated protomers...
October 2, 2017: Annual Review of Pharmacology and Toxicology
Eshan Ghosh, Ashish Srivastava, Mithu Baidya, Punita Kumari, Hemlata Dwivedi, Kumari Nidhi, Ravi Ranjan, Shalini Dogra, Akiko Koide, Prem N Yadav, Sachdev S Sidhu, Shohei Koide, Arun K Shukla
Beta-arrestins (βarrs) critically mediate desensitization, endocytosis and signalling of G protein-coupled receptors (GPCRs), and they scaffold a large number of interaction partners. However, allosteric modulation of their scaffolding abilities and direct targeting of their interaction interfaces to modulate GPCR functions selectively have not been fully explored yet. Here we identified a series of synthetic antibody fragments (Fabs) against different conformations of βarrs from phage display libraries. Several of these Fabs allosterically and selectively modulated the interaction of βarrs with clathrin and ERK MAP kinase...
October 2, 2017: Nature Nanotechnology
Aashish Manglik, Andrew Kruse
G protein-coupled receptors (GPCRs) are critical regulators of human physiology and are the largest single class of therapeutic drug targets. Although GPCRs regulate highly diverse physiology, they share a common signaling mechanism whereby extracellular stimuli induce conformational changes in the receptor that enable activation of heterotrimeric G proteins and other intracellular effectors. Advances in GPCR structural biology have made it possible to examine ligand-induced GPCR activation at an unprecedented level of detail...
October 2, 2017: Biochemistry
Wataru Nomura
 Interactions between bio-macromolecules such as proteins, DNA, and polysaccharides play pivotal roles in maintaining homeostasis in living systems. For elucidating the function of biomolecules, peptides are powerful tools, compared to native proteins, because of their lower molecular weights, compatibility with chemical modification, and predictability of interaction with the target molecules. These advantages enabled us to develop peptide-based functional molecules. However, for the purposes of controlling or regulating biomolecule functions, designing artificial proteins is also an effective approach...
2017: Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan
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