Intracrine signaling through lipid mediators and their cognate nuclear G-protein-coupled receptors: a paradigm based on PGE2, PAF, and LPA1 receptorsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

Prostaglandins (PGs), platelet-activating factor (PAF), and lysophosphatidic acid (LPA) are ubiquitous lipid mediators that play important roles in inflammation, cardiovascular homeostasis, and immunity and are also known to modulate gene expression of specific pro-inflammatory genes. The mechanism of action of these lipids is thought to be primarily dependent on their specific plasma membrane receptors belonging to the superfamily of G-protein-coupled receptors (GPCR). Increasing evidence suggests the existence of a functional intracellular GPCR population. It has been proposed that immediate effects are mediated via cell surface receptors whereas long-term responses are dependent upon intracellular receptor effects. Indeed, receptors for PAF, LPA, and PGE2 (specifically EP1, EP3, and EP4) localize at the cell nucleus of cerebral microvascular endothelial cells of newborn pigs, rat hepatocytes, and cells overexpressing each receptor. Stimulation of isolated nuclei with these lipids reveals biological functions including transcriptional regulation of major genes, namely c-fos, cylooxygenase-2, and endothelial as well as inducible nitric oxide synthase. In the present review, we shall focus on the nuclear localization and signaling of GPCRs recognizing PGE2, PAF, and LPA phospholipids as ligands. Mechanisms on how nuclear PGE2, PAF, and LPA receptors activate gene transcription and nuclear localization pathways are presented. Intracrine signaling for lipid mediators uncover novel pathways to elicit their effects; accordingly, intracellular GPCRs constitute a distinctive mode of action for gene regulation.

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NPY, ET-1, and Ang II nuclear receptors in human endocardial endothelial cellsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y05-158 ◽

2006 ◽

Vol 84 (3-4) ◽

pp. 299-307 ◽

Cited By ~ 19

Author(s):

Danielle Jacques ◽

Sawsan Sader ◽

Claudine Perreault ◽

Dima Abdel-Samad ◽

Farah Jules ◽

...

Keyword(s):

G Protein ◽

G Protein Coupled Receptors ◽

Membrane Receptors ◽

Ang Ii ◽

Special Issue ◽

A Cell ◽

Endocardial Endothelial Cells ◽

Plasma Membrane Receptors ◽

G Protein Coupled ◽

Selection Of

Neuropeptide Y (NPY), endothelin-1 (ET-1), and angiotensin II (Ang II) are peptides that are known to play many important roles in cardiovascular homeostasis. The physiological actions of these peptides are thought to be primarily mediated by plasma membrane receptors that belong to the G-protein-coupled receptor superfamily. However, there is increasing evidence that suggests the existence of functional G-protein-coupled receptors at the level of the nucleus and that the nucleus could be a cell within a cell. Here, we review our work showing the presence in the nucleus of the NPY Y1 receptor, the ETA and ETB receptors, as well as the AT1 and AT2 receptors and their respective ligands. This work was carried out in 20-week-old fetal human endocardial endothelial cells. Our results demonstrate that nuclear Y1, AT1, and ETA receptors modulate nuclear calcium in these cells.

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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.

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y05-127 ◽

2006 ◽

Vol 84 (3-4) ◽

pp. 287-297 ◽

Cited By ~ 124

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.

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Imaging of persistent cAMP signaling by internalized G protein-coupled receptors

Journal of Molecular Endocrinology ◽

10.1677/jme-10-0014 ◽

2010 ◽

Vol 45 (1) ◽

pp. 1-8 ◽

Cited By ~ 47

Author(s):

Davide Calebiro ◽

Viacheslav O Nikolaev ◽

Martin J Lohse

Keyword(s):

G Protein ◽

Intracellular Signaling ◽

Current Model ◽

Living Cells ◽

G Protein Coupled Receptors ◽

Membrane Receptors ◽

Optical Methods ◽

Camp Signaling ◽

Gpcr Signaling ◽

G Protein Coupled

G protein-coupled receptors (GPCRs) are the largest family of plasma membrane receptors. They mediate the effects of several endogenous cues and serve as important pharmacological targets. Although many biochemical events involved in GPCR signaling have been characterized in great detail, little is known about their spatiotemporal dynamics in living cells. The recent advent of optical methods based on fluorescent resonance energy transfer allows, for the first time, to directly monitor GPCR signaling in living cells. Utilizing these methods, it has been recently possible to show that the receptors for two protein/peptide hormones, the TSH and the parathyroid hormone, continue signaling to cAMP after their internalization into endosomes. This type of intracellular signaling is persistent and apparently triggers specific cellular outcomes. Here, we review these recent data and explain the optical methods used for such studies. Based on these findings, we propose a revision of the current model of the GPCR–cAMP signaling pathway to accommodate receptor signaling at endosomes.

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

Journal of Cell Science ◽

10.1242/jcs.113.13.2463 ◽

2000 ◽

Vol 113 (13) ◽

pp. 2463-2470 ◽

Cited By ~ 1

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.

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

International Journal of Molecular Sciences ◽

10.3390/ijms222212329 ◽

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.

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The tyrosine phosphatase CD148 is an essential positive regulator of platelet activation and thrombosis

Blood ◽

10.1182/blood-2008-08-174318 ◽

2009 ◽

Vol 113 (20) ◽

pp. 4942-4954 ◽

Cited By ~ 84

Author(s):

Yotis A. Senis ◽

Michael G. Tomlinson ◽

Stuart Ellison ◽

Alexandra Mazharian ◽

Jenson Lim ◽

...

Keyword(s):

G Protein ◽

Platelet Activation ◽

Drug Target ◽

Tyrosine Phosphatase ◽

Underlying Mechanism ◽

G Protein Coupled Receptors ◽

Bleeding Tendency ◽

Platelet Surface ◽

Surface Receptors ◽

G Protein Coupled

Abstract Platelets play a fundamental role in hemostasis and thrombosis. They are also involved in pathologic conditions resulting from blocked blood vessels, including myocardial infarction and ischemic stroke. Platelet adhesion, activation, and aggregation at sites of vascular injury are regulated by a diverse repertoire of tyrosine kinase–linked and G protein–coupled receptors. Src family kinases (SFKs) play a central role in initiating and propagating signaling from several platelet surface receptors; however, the underlying mechanism of how SFK activity is regulated in platelets remains unclear. CD148 is the only receptor-like protein tyrosine phosphatase identified in platelets to date. In the present study, we show that mutant mice lacking CD148 exhibited a bleeding tendency and defective arterial thrombosis. Basal SFK activity was found to be markedly reduced in CD148-deficient platelets, resulting in a global hyporesponsiveness to agonists that signal through SFKs, including collagen and fibrinogen. G protein–coupled receptor responses to thrombin and other agonists were also marginally reduced. These results highlight CD148 as a global regulator of platelet activation and a novel antithrombotic drug target.

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Expression of G protein coupled receptors in a cell-free translational system using detergents and thioredoxin-fusion vectors

Protein Expression and Purification ◽

10.1016/j.pep.2005.01.013 ◽

2005 ◽

Vol 41 (1) ◽

pp. 27-37 ◽

Cited By ~ 135

Author(s):

Goshi Ishihara ◽

Mie Goto ◽

Mihoro Saeki ◽

Kaori Ito ◽

Tetsuya Hori ◽

...

Keyword(s):

G Protein ◽

G Protein Coupled Receptors ◽

A Cell ◽

G Protein Coupled

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Identification and Functional Analysis of G Protein-Coupled Receptors in 20-Hydroxyecdysone Signaling From the Helicoverpa armigera Genome

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.753787 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yan-Li Li ◽

Yan-Xue Li ◽

Xiao-Pei Wang ◽

Xin-Le Kang ◽

Ke-Qin Guo ◽

...

Keyword(s):

G Protein ◽

Helicoverpa Armigera ◽

Hormone Receptor ◽

G Protein Coupled Receptors ◽

Membrane Receptors ◽

Pest Species ◽

Metamorphic Stage ◽

Adipokinetic Hormone ◽

Helicoverpa Armígera ◽

G Protein Coupled

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors in animals and humans, which transmit various signals from the extracellular environment into cells. Studies have reported that several GPCRs transmit the same signal; however, the mechanism is unclear. In the present study, we identified all 122 classical GPCRs from the genome of Helicoverpa armigera, a lepidopteran pest species. Twenty-four GPCRs were identified as upregulated at the metamorphic stage by comparing the transcriptomes of the midgut at the metamorphic and feeding stages. Nine of them were confirmed to be upregulated at the metamorphic stage. RNA interference in larvae revealed the prolactin-releasing peptide receptor (PRRPR), smoothened (SMO), adipokinetic hormone receptor (AKHR), and 5-hydroxytryptamine receptor (HTR) are involved in steroid hormone 20-hydroxyecdysone (20E)-promoted pupation. Frizzled 7 (FZD7) is involved in growth, while tachykinin-like peptides receptor 86C (TKR86C) had no effect on growth and pupation. Via these GPCRs, 20E regulated the expression of different genes, respectively, including Pten (encoding phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase), FoxO (encoding forkhead box O), BrZ7 (encoding broad isoform Z7), Kr-h1 (encoding Krüppel homolog 1), Wnt (encoding Wingless/Integrated) and cMyc, with hormone receptor 3 (HHR3) as their common regulating target. PRRPR was identified as a new 20E cell membrane receptor using a binding assay. These data suggested that 20E, via different GPCRs, regulates different gene expression to integrate growth and development.

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The complex role of Prostaglandin E2-EP receptor signaling in wound healing

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00185.2020 ◽

2020 ◽

Author(s):

Kristy E. Gilman ◽

Kirsten H. Limesand

Keyword(s):

Wound Healing ◽

G Protein ◽

Lipid Mediators ◽

G Protein Coupled Receptors ◽

Prostaglandin E ◽

Receptor Signaling ◽

Wound Healing Response ◽

Ep Receptor ◽

G Protein Coupled

Prostaglandins are critical lipid mediators involved in the wound healing response, with prostaglandin E2 (PGE2) being the most complex and exhibiting the most diverse physiological outputs. PGE2 signals via four G-protein coupled receptors, termed EP-receptors 1-4, that induce distinct signaling pathways upon activation and lead to an array of different outputs. Recent studies examining the role of PGE2 and EP receptor signaling in wound healing following various forms of tissue damage are discussed in this review.

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