scholarly journals Emerging Roles of Protease-Activated Receptors (PARs) in the Modulation of Synaptic Transmission and Plasticity

2021 ◽  
Vol 22 (2) ◽  
pp. 869
Author(s):  
Rachel Price ◽  
Nicola Biagio Mercuri ◽  
Ada Ledonne
Keyword(s):  
G Protein Coupled Receptors ◽  
Synaptic Efficacy ◽  
Protease Activated Receptors ◽  
Gabaergic Transmission ◽  
Cellular Survival ◽  
Physiological Conditions ◽  
Tethered Ligand ◽  
G Protein Coupled ◽  
The Brain ◽  
Unique Mechanism

Protease-activated receptors (PARs) are a class of G protein-coupled receptors (GPCRs) with a unique mechanism of activation, prompted by a proteolytic cleavage in their N-terminal domain that uncovers a tethered ligand, which binds and stimulates the same receptor. PARs subtypes (PAR1-4) have well-documented roles in coagulation, hemostasis, and inflammation, and have been deeply investigated for their function in cellular survival/degeneration, while their roles in the brain in physiological conditions remain less appreciated. Here, we describe PARs’ effects in the modulation of neurotransmission and synaptic plasticity. Available evidence, mainly concerning PAR1-mediated and PAR2-mediated regulation of glutamatergic and GABAergic transmission, supports that PARs are important modulators of synaptic efficacy and plasticity in normal conditions.

scholarly journals Protease Activated Receptors and Arthritis

2021 ◽  
Vol 22 (17) ◽  
pp. 9352
Author(s):  
Flora Lucena ◽  
Jason J. McDougall
Keyword(s):  
Serine Proteases ◽  
Vascular Reactivity ◽  
Structural Integrity ◽  
Therapeutic Potential ◽  
G Protein Coupled Receptors ◽  
Tissue Remodelling ◽  
Protease Activated Receptors ◽  
Tethered Ligand ◽  
Arthritic Joints ◽  
G Protein Coupled

The catabolic and destructive activity of serine proteases in arthritic joints is well known; however, these enzymes can also signal pain and inflammation in joints. For example, thrombin, trypsin, tryptase, and neutrophil elastase cleave the extracellular N-terminus of a family of G protein-coupled receptors and the remaining tethered ligand sequence then binds to the same receptor to initiate a series of molecular signalling processes. These protease activated receptors (PARs) pervade multiple tissues and cells throughout joints where they have the potential to regulate joint homeostasis. Overall, joint PARs contribute to pain, inflammation, and structural integrity by altering vascular reactivity, nociceptor sensitivity, and tissue remodelling. This review highlights the therapeutic potential of targeting PARs to alleviate the pain and destructive nature of elevated proteases in various arthritic conditions.

Protease-activated receptor 2: activation, signalling and function

2003 ◽  
Vol 31 (6) ◽  
pp. 1191-1197 ◽  
Author(s):  
G.S. Cottrell ◽  
S. Amadesi ◽  
F. Schmidlin ◽  
N. Bunnett
Keyword(s):  
Inflammatory Cells ◽  
Coagulation Factors ◽  
G Protein Coupled Receptors ◽  
Protease Activated Receptors ◽  
Mitogen Activated Protein ◽  
Tethered Ligand ◽  
And Function ◽  
Protease Activated Receptor 2 ◽  
G Protein Coupled ◽  
Deficient Mice

PARs (protease-activated receptors) are a family of four G-protein-coupled receptors for proteases from the circulation, inflammatory cells and epithelial tissues. This report focuses on PAR2, which plays an important role in inflammation and pain. Pancreatic (trypsin I and II) and extrapancreatic (trypsin IV) trypsins, mast cell tryptase and coagulation factors VIIa and Xa cleave and activate PAR2. Proteases cleave PAR2 to expose a tethered ligand that binds to the cleaved receptor. Despite this irreversible activation, PAR2 signalling is attenuated by β-arrestin-mediated desensitization and endocytosis, and by lysosomal targeting and degradation, which requires ubiquitination of PAR2. β-Arrestins also act as scaffolds for the assembly of multi-protein signalling complexes that determine the location and function of activated mitogen-activated protein kinases. Observations of PAR2-deficient mice support a role for PAR2 in inflammation, and many of the effects of PAR2 activators promote inflammation. Inflammation is mediated in part by activation of PAR2 in the peripheral nervous system, which results in neurogenic inflammation and hyperalgesia.

Adenosine Receptors in the Central Nervous System

Physiology ◽  
1995 ◽  
Vol 10 (3) ◽  
pp. 122-128 ◽  
Author(s):  
BB Fredholm
Keyword(s):  
Neurotransmitter Release ◽  
Cell Function ◽  
G Protein Coupled Receptors ◽  
Neuronal Firing ◽  
Ischemic Brain ◽  
Physiological Conditions ◽  
Neuronal Firing Rate ◽  
The Central Nervous System ◽  
G Protein Coupled ◽  
The Brain

Adenosine is present in the brain under physiological conditions and acts on G protein-coupled receptors. Adenosine regulates neurotransmitter release and neuronal firing rate, dopaminergic neurotransmission, glial cell function, and cerebral blood flow. Adenosine is implicated in sleep/wakefulness and protection against ischemic brain damage, epilepsy, and pain.

Selective recruitment of arrestin-3 to clathrin coated pits upon stimulation of G protein-coupled receptors

2000 ◽  
Vol 113 (13) ◽  
pp. 2463-2470 ◽  
Author(s):  
F. Santini ◽  
R.B. Penn ◽  
A.W. Gagnon ◽  
J.L. Benovic ◽  
J.H. Keen
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Coated Pits ◽  
Over Expression ◽  
Physiological Conditions ◽  
A Cell ◽  
G Protein Coupled ◽  
Comparable Magnitude

Non-visual arrestins (arrestin-2 and arrestin-3) play critical roles in the desensitization and internalization of many G protein-coupled receptors. In vitro experiments have shown that both non-visual arrestins bind with high and approximately comparable affinities to activated, phosphorylated forms of receptors. They also exhibit high affinity binding, again of comparable magnitude, to clathrin. Further, agonist-promoted internalization of many receptors has been found to be stimulated by exogenous over-expression of either arrestin2 or arrestin3. The existence of multiple arrestins raises the question whether stimulated receptors are selective for a specific endogenous arrestin under more physiological conditions. Here we address this question in RBL-2H3 cells, a cell line that expresses comparable levels of endogenous arrestin-2 and arrestin-3. When (beta)(2)-adrenergic receptors are stably expressed in these cells the receptors internalize efficiently following agonist stimulation. However, by immunofluorescence microscopy we determine that only arrestin-3, but not arrestin-2, is rapidly recruited to clathrin coated pits upon receptor stimulation. Similarly, in RBL-2H3 cells that stably express physiological levels of m1AChR, the addition of carbachol selectively induces the localization of arrestin-3, but not arrestin-2, to coated pits. Thus, this work demonstrates coupling of G protein-coupled receptors to a specific non-visual arrestin in an in vivo setting.

scholarly journals The cell biology of smell

2010 ◽  
Vol 191 (3) ◽  
pp. 443-452 ◽  
Author(s):  
Shannon DeMaria ◽  
John Ngai
Keyword(s):  
Olfactory System ◽  
Cell Biology ◽  
Odorant Receptor ◽  
Large Family ◽  
G Protein Coupled Receptors ◽  
Odorant Receptors ◽  
Chemical Structures ◽  
Wide Range ◽  
G Protein Coupled ◽  
The Brain

The olfactory system detects and discriminates myriad chemical structures across a wide range of concentrations. To meet this task, the system utilizes a large family of G protein–coupled receptors—the odorant receptors—which are the chemical sensors underlying the perception of smell. Interestingly, the odorant receptors are also involved in a number of developmental decisions, including the regulation of their own expression and the patterning of the olfactory sensory neurons' synaptic connections in the brain. This review will focus on the diverse roles of the odorant receptor in the function and development of the olfactory system.

Transmembrane Signaling in the Brain by Serotonin, A Key Regulator of Physiology and Emotion

2005 ◽  
Vol 25 (5-6) ◽  
pp. 363-385 ◽  
Author(s):  
Tatyana Adayev ◽  
Buddima Ranasinghe ◽  
Probal Banerjee
Keyword(s):  
Gene Expression ◽  
Immune Cells ◽  
Functional Role ◽  
Living Organism ◽  
Covalent Modification ◽  
G Protein Coupled Receptors ◽  
And Behavior ◽  
G Protein Coupled ◽  
Compare And Contrast ◽  
The Brain

Serotonin (5-HT) is an ancient chemical that plays a crucial functional role in almost every living organism. It regulates platelet aggregation, activation of immune cells, and contraction of stomach and intestinal muscles. In addition, serotonin acts as a neurotransmitter in the brain and the peripheral nervous system. These activities are initiated by the binding of serotonin to 15 or more receptors that are pharmacologically classified into seven groups, 5-HT1 through 5-HT7. Each group is further divided into subgroups of receptors that are homologous but are encoded by discrete genes. With the exception of the 5-HT3 receptor-a cation channel—all of the others are G protein-coupled receptors that potentially activate or inhibit a large number of biochemical cascades. This review will endeavor to compare and contrast such signaling pathways with special attention to their tissue-specific occurrence, their possible role in immediate effects on covalent modification of other proteins, and relatively slower effects on gene expression, physiology and behavior.

scholarly journals Effect of 5-hydroxytryptamine Receptor in the Lower Esophageal Sphincter Regulation Mechanism

2020 ◽  
Vol 3 (6) ◽  
Author(s):  
Hefei Li ◽  
Junfeng Liu ◽  
Xixuan Zhang ◽  
Zhiwei Lai ◽  
Zhen Gao ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Regulation Mechanism ◽  
Visceral Sensitivity ◽  
Gastrointestinal Dysfunction ◽  
Secretion Regulation ◽  
The Central Nervous System ◽  
Esophageal Sphincter ◽  
G Protein Coupled ◽  
The Brain

As a neurotransmitter and avascular active substance, the 5-hydroxytryptamine (5-HT, serotonin) is widely distributed in the central nervous system and surrounding tissues. The 5-HT can play its role by acting on its corresponding 5-HT receptor. Nowadays, the 5-HT receptor can be classified into seven, according to different signal transduction method of receptors, the 5-HT3 receptor belongs to the ligand-gated ion channels, while other six 5-HT receptors are involved into the G protein-coupled receptors and play the biological role by binding to specific G protein-coupled receptors (GPCRs) on the surface of the cell membrane. The 5-HT plays an important role in the brain-gut information transmission and studies showed that the physiological stimulations like having meals, and pathological stimulations like ischemia and stress could promote the release of the 5-HT. In the gastrointestinal tract, the 5-HT is closely related to gastrointestinal sensitivity, gastrointestinal movement and secretion regulation, as well as many gastrointestinal dysfunction disorders, such as gastrointestinal power and visceral sensitivity abnormality and abnormalities of brain-gut axis.

scholarly journals Melatonin

2002 ◽  
Vol 4 (1) ◽  
pp. 57-72 ◽  
Keyword(s):  
Seasonal Affective Disorder ◽  
Physiological Role ◽  
G Protein Coupled Receptors ◽  
The Body ◽  
Receptor Subtypes ◽  
Seasonal Breeding ◽  
Livestock Management ◽  
G Protein Coupled ◽  
The Brain ◽  
Melatonin Production

Melatonin (MEL) is a hormone synthesized and secreted by the pineal gland deep within the brain in response to photoperiodic cues relayed from the retina via an endogenous circadian oscillator within the suprachiasmatic nucleus in the hypothalamus. The circadian rhythm of melatonin production and release, characterized by nocturnal activity and daytime quiescence, is an important temporal signal to the body structures that can read it. Melatonin acts through high-affinity receptors located centrally and in numerous peripheral organs. Different receptor subtypes have been cloned and characterized: MT(1) and MT(2) (transmembrane G-protein-coupled receptors), and MT(3). However, their physiological role remains unelucidated, although livestock management applications already include the control of seasonal breeding and milk production. As for potential therapeutic applications, exogenous melatonin or a melatonin agonist and selective 5-hydroxytrypiamine receptor (5-HT(2c)) antagonist, eg, S 20098, can be used to manipulate circadian processes such as the sleep-vake cycle, which are frequently disrupted in many conditions, most notably seasonal affective disorder.

scholarly journals Evaluation on Potential Contributions of Protease Activated Receptors Related Mediators in Allergic Inflammation

2014 ◽  
Vol 2014 ◽  
pp. 1-20 ◽  
Author(s):  
Huiyun Zhang ◽  
Xiaoning Zeng ◽  
Shaoheng He
Keyword(s):  
Serine Proteases ◽  
Inflammatory Cell ◽  
Allergic Inflammation ◽  
G Protein Coupled Receptors ◽  
Cell Behavior ◽  
Protease Activated Receptors ◽  
Pathologic Process ◽  
Allergic Disorders ◽  
G Protein Coupled

Protease activated receptors (PARs) have been recognized as a distinctive four-member family of seven transmembrane G protein-coupled receptors (GPCRs) that can be cleaved by certain serine proteases. In recent years, there has been considerable interest in the role of PARs in allergic inflammation, the fundamental pathologic changes of allergy, but the potential roles of PARs in allergy remain obscure. Since many of these proteases are produced and actively involved in the pathologic process of inflammation including exudation of plasma components, inflammatory cell infiltration, and tissue damage and repair, PARs appear to make important contribution to allergy. The aim of the present review is to summarize the expression of PARs in inflammatory and structural cells, the influence of agonists or antagonists of PARs on cell behavior, and the involvement of PARs in allergic disorders, which will help us to better understand the roles of serine proteases and PARs in allergy.

scholarly journals Emerging roles of adhesion G protein-coupled receptors

2021 ◽  
Author(s):  
Matthew Rosa ◽  
Timothy Noel ◽  
Matthew Harris ◽  
Graham Ladds
Keyword(s):  
G Protein ◽  
Conformational Changes ◽  
Current Knowledge ◽  
Receptor Activation ◽  
G Protein Coupled Receptors ◽  
Extracellular Region ◽  
Extracellular Matrix Components ◽  
Ligand Interactions ◽  
Tethered Ligand ◽  
G Protein Coupled

Adhesion G protein-coupled receptors (aGPCRs) form a sub-group within the GPCR superfamily. Their distinctive structure contains an abnormally large N-terminal, extracellular region with a GPCR autoproteolysis-inducing (GAIN) domain. In most aGPCRs, the GAIN domain constitutively cleaves the receptor into two fragments. This process is often required for aGPCR signalling. Over the last two decades, much research has focussed on aGPCR-ligand interactions, in an attempt to deorphanize the family. Most ligands have been found to bind to regions N-terminal to the GAIN domain. These receptors may bind a variety of ligands, ranging across membrane-bound proteins and extracellular matrix components. Recent advancements have revealed a conserved method of aGPCR activation involving a tethered ligand within the GAIN domain. Evidence for this comes from increased activity in receptor mutants exposing the tethered ligand. As a result, G protein-coupling partners of aGPCRs have been more extensively characterised, making use of their tethered ligand to create constitutively active mutants. This has led to demonstrations of aGPCR function in, for example, neurodevelopment and tumour growth. However, questions remain around the ligands that may bind many aGPCRs, how this binding is translated into changes in the GAIN domain, and the exact mechanism of aGPCR activation following GAIN domain conformational changes. This review aims to examine the current knowledge around aGPCR activation, including ligand binding sites, the mechanism of GAIN domain-mediated receptor activation and how aGPCR transmembrane domains may relate to activation. Other aspects of aGPCR signalling will be touched upon, such as downstream effectors and physiological roles.

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