scholarly journals Uncovering Molecular Mechanisms Involved in Activation of G Protein-Coupled Receptors

2000 ◽  
Vol 21 (1) ◽  
pp. 90-113 ◽  
Author(s):  
Ulrik Gether
Keyword(s):  
G Protein ◽  
Molecular Mechanisms ◽  
G Protein Coupled Receptors ◽  
G Protein Coupled

G-protein-coupled receptors signalling at the cell nucleus: an emerging paradigmThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 287-297 ◽  
Author(s):  
Fernand Gobeil ◽  
Audrey Fortier ◽  
Tang Zhu ◽  
Michela Bossolasco ◽  
Martin Leduc ◽  
...  
Keyword(s):  
G Protein ◽  
Cell Nucleus ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Cell Metabolism ◽  
Hormone Secretion ◽  
G Protein Coupled Receptors ◽  
A Cell ◽  
G Protein Coupled

G-protein-coupled receptors (GPCRs) comprise a wide family of monomeric heptahelical glycoproteins that recognize a broad array of extracellular mediators including cationic amines, lipids, peptides, proteins, and sensory agents. Thus far, much attention has been given towards the comprehension of intracellular signaling mechanisms activated by cell membrane GPCRs, which convert extracellular hormonal stimuli into acute, non-genomic (e.g., hormone secretion, muscle contraction, and cell metabolism) and delayed, genomic biological responses (e.g., cell division, proliferation, and apoptosis). However, with respect to the latter response, there is compelling evidence for a novel intracrine mode of genomic regulation by GPCRs that implies either the endocytosis and nuclear translocation of peripheral-liganded GPCR and (or) the activation of nuclearly located GPCR by endogenously produced, nonsecreted ligands. A noteworthy example of the last scenario is given by heptahelical receptors that are activated by bioactive lipoids (e.g., PGE2 and PAF), many of which may be formed from bilayer membranes including those of the nucleus. The experimental evidence for the nuclear localization and signalling of GPCRs will be reviewed. We will also discuss possible molecular mechanisms responsible for the atypical compartmentalization of GPCRs at the cell nucleus, along with their role in gene expression.

scholarly journals Ionotropic and Metabotropic Proton-Sensing Receptors Involved in Airway Inflammation in Allergic Asthma

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Haruka Aoki ◽  
Chihiro Mogi ◽  
Fumikazu Okajima
Keyword(s):  
Airway Inflammation ◽  
Allergic Asthma ◽  
G Protein ◽  
Molecular Mechanisms ◽  
G Protein Coupled Receptors ◽  
Airway Smooth Muscle Cells ◽  
Transient Receptor Potential Vanilloid ◽  
Acidic Ph ◽  
Airway Responses ◽  
G Protein Coupled

An acidic microenvironment has been shown to evoke a variety of airway responses, including cough, bronchoconstriction, airway hyperresponsiveness (AHR), infiltration of inflammatory cells in the lung, and stimulation of mucus hyperproduction. Except for the participation of transient receptor potential vanilloid-1 (TRPV1) and acid-sensing ion channels (ASICs) in severe acidic pH (of less than 6.0)-induced cough and bronchoconstriction through sensory neurons, the molecular mechanisms underlying extracellular acidic pH-induced actions in the airways have not been fully understood. Recent studies have revealed that ovarian cancer G protein-coupled receptor 1 (OGR1)-family G protein-coupled receptors, which sense pH of more than 6.0, are expressed in structural cells, such as airway smooth muscle cells and epithelial cells, and in inflammatory and immune cells, such as eosinophils and dendritic cells. They function in a variety of airway responses related to the pathophysiology of inflammatory diseases, including allergic asthma. In the present review, we discuss the roles of ionotropic TRPV1 and ASICs and metabotropic OGR1-family G protein-coupled receptors in the airway inflammation and AHR in asthma and respiratory diseases.

scholarly journals Misfolded G Protein-Coupled Receptors and Endocrine Disease. Molecular Mechanisms and Therapeutic Prospects

2021 ◽  
Vol 22 (22) ◽  
pp. 12329
Author(s):  
Alfredo Ulloa-Aguirre ◽  
Teresa Zariñán ◽  
Eduardo Jardón-Valadez
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
G Protein Coupled Receptors ◽  
Membrane Receptors ◽  
Therapeutic Interventions ◽  
Endocrine Function ◽  
Receptor Protein ◽  
G Protein Coupled

Misfolding of G protein-coupled receptors (GPCRs) caused by mutations frequently leads to disease due to intracellular trapping of the conformationally abnormal receptor. Several endocrine diseases due to inactivating mutations in GPCRs have been described, including X-linked nephrogenic diabetes insipidus, thyroid disorders, familial hypocalciuric hypercalcemia, obesity, familial glucocorticoid deficiency [melanocortin-2 receptor, MC2R (also known as adrenocorticotropin receptor, ACTHR), and reproductive disorders. In these mutant receptors, misfolding leads to endoplasmic reticulum retention, increased intracellular degradation, and deficient trafficking of the abnormal receptor to the cell surface plasma membrane, causing inability of the receptor to interact with agonists and trigger intracellular signaling. In this review, we discuss the mechanisms whereby mutations in GPCRs involved in endocrine function in humans lead to misfolding, decreased plasma membrane expression of the receptor protein, and loss-of-function diseases, and also describe several experimental approaches employed to rescue trafficking and function of the misfolded receptors. Special attention is given to misfolded GPCRs that regulate reproductive function, given the key role played by these particular membrane receptors in sexual development and fertility, and recent reports on promising therapeutic interventions targeting trafficking of these defective proteins to rescue completely or partially their normal function.

Molecular mechanisms of GABAB receptor activation: new insights from the mechanism of action of CGP7930, a positive allosteric modulator

2004 ◽  
Vol 32 (5) ◽  
pp. 871-872 ◽  
Author(s):  
V. Binet ◽  
C. Goudet ◽  
C. Brajon ◽  
L. Le Corre ◽  
F. Acher ◽  
...  
Keyword(s):  
G Protein ◽  
Mechanism Of Action ◽  
Molecular Mechanisms ◽  
Gabab Receptor ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Class Iii ◽  
G Protein Coupled ◽  
New Strategies

The GABAB (γ-aminobutyric acid-B) receptor is composed of two subunits, GABAB1 and GABAB2. Both subunits share structural homology with other class-III G-protein-coupled receptors. They contain two main domains, a heptahelical domain typical of all G-protein-coupled receptors and a large ECD (extracellular domain). It has not been demonstrated whether the association of these two subunits is always required for function. However, GABAB2 plays a major role in coupling with G-proteins, and GABAB1 has been shown to bind GABA. To date, only ligands interacting with GABAB1-ECD have been identified. In the present study, we explored the mechanism of action of CGP7930, a compound described as a positive allosteric regulator of the GABAB receptor. We have shown that it can weakly activate the wild-type GABAB receptor, but also the GABAB2 expressed alone, thus being the first described agonist of GABAB2. CGP7930 retains its weak agonist activity on a GABAB2 subunit deleted of its ECD. Thus the heptahelical domain of GABAB2 behaves similar to a rhodopsin-like receptor. These results open new strategies for studying the mechanism of activation of GABAB receptor and examine any possible role of GABAB2.

scholarly journals G Protein-Coupled Receptors in Taste Physiology and Pharmacology

2020 ◽  
Vol 11 ◽  
Author(s):  
Raise Ahmad ◽  
Julie E. Dalziel
Keyword(s):  
Binding Site ◽  
G Protein ◽  
Molecular Mechanisms ◽  
Taste Receptor ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Type I ◽  
Taste Receptors ◽  
Agonist Binding ◽  
G Protein Coupled

Heterotrimeric G protein-coupled receptors (GPCRs) comprise the largest receptor family in mammals and are responsible for the regulation of most physiological functions. Besides mediating the sensory modalities of olfaction and vision, GPCRs also transduce signals for three basic taste qualities of sweet, umami (savory taste), and bitter, as well as the flavor sensation kokumi. Taste GPCRs reside in specialised taste receptor cells (TRCs) within taste buds. Type I taste GPCRs (TAS1R) form heterodimeric complexes that function as sweet (TAS1R2/TAS1R3) or umami (TAS1R1/TAS1R3) taste receptors, whereas Type II are monomeric bitter taste receptors or kokumi/calcium-sensing receptors. Sweet, umami and kokumi receptors share structural similarities in containing multiple agonist binding sites with pronounced selectivity while most bitter receptors contain a single binding site that is broadly tuned to a diverse array of bitter ligands in a non-selective manner. Tastant binding to the receptor activates downstream secondary messenger pathways leading to depolarization and increased intracellular calcium in TRCs, that in turn innervate the gustatory cortex in the brain. Despite recent advances in our understanding of the relationship between agonist binding and the conformational changes required for receptor activation, several major challenges and questions remain in taste GPCR biology that are discussed in the present review. In recent years, intensive integrative approaches combining heterologous expression, mutagenesis and homology modeling have together provided insight regarding agonist binding site locations and molecular mechanisms of orthosteric and allosteric modulation. In addition, studies based on transgenic mice, utilizing either global or conditional knock out strategies have provided insights to taste receptor signal transduction mechanisms and their roles in physiology. However, the need for more functional studies in a physiological context is apparent and would be enhanced by a crystallized structure of taste receptors for a more complete picture of their pharmacological mechanisms.

scholarly journals The Role of G Protein-Coupled Receptors (GPCRs) and Calcium Signaling in Schizophrenia. Focus on GPCRs Activated by Neurotransmitters and Chemokines

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1228
Author(s):  
Tomasz Boczek ◽  
Joanna Mackiewicz ◽  
Marta Sobolczyk ◽  
Julia Wawrzyniak ◽  
Malwina Lisek ◽  
...  
Keyword(s):  
G Protein ◽  
Psychiatric Illness ◽  
Antipsychotic Drugs ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
G Protein Coupled Receptors ◽  
Disease Development ◽  
Complex Picture ◽  
G Protein Coupled

Schizophrenia is a common debilitating disease characterized by continuous or relapsing episodes of psychosis. Although the molecular mechanisms underlying this psychiatric illness remain incompletely understood, a growing body of clinical, pharmacological, and genetic evidence suggests that G protein-coupled receptors (GPCRs) play a critical role in disease development, progression, and treatment. This pivotal role is further highlighted by the fact that GPCRs are the most common targets for antipsychotic drugs. The GPCRs activation evokes slow synaptic transmission through several downstream pathways, many of them engaging intracellular Ca2+ mobilization. Dysfunctions of the neurotransmitter systems involving the action of GPCRs in the frontal and limbic-related regions are likely to underly the complex picture that includes the whole spectrum of positive and negative schizophrenia symptoms. Therefore, the progress in our understanding of GPCRs function in the control of brain cognitive functions is expected to open new avenues for selective drug development. In this paper, we review and synthesize the recent data regarding the contribution of neurotransmitter-GPCRs signaling to schizophrenia symptomology.

Sign in / Sign up

Export Citation Format

Share Document