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Suo WZ. GRK5 Deficiency Causes Mild Cognitive Impairment due to Alzheimer's Disease. J Alzheimers Dis 2021; 85:1399-1410. [PMID: 34958040 DOI: 10.3233/jad-215379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Prevention of Alzheimer's disease (AD) is a high priority mission while searching for a disease modifying therapy for AD, a devastating major public health crisis. Clinical observations have identified a prodromal stage of AD for which the patients have mild cognitive impairment (MCI) though do not yet meet AD diagnostic criteria. As an identifiable transitional stage before the onset of AD, MCI should become the high priority target for AD prevention, assuming successful prevention of MCI and/or its conversion to AD also prevents the subsequent AD. By pulling this string, one demonstrated cause of amnestic MCI appears to be the deficiency of G protein-coupled receptor-5 (GRK5). The most compelling evidence is that GRK5 knockout (GRK5KO) mice naturally develop into aMCI during aging. Moreover, GRK5 deficiency was reported to occur during prodromal stage of AD in CRND8 transgenic mice. When a GRK5KO mouse was crossbred with Tg2576 Swedish amyloid precursor protein transgenic mouse, the resulted double transgenic GAP mice displayed exaggerated behavioral and pathological changes across the spectrum of AD pathogenesis. Therefore, the GRK5 deficiency possesses unique features and advantage to serve as a prophylactic therapeutic target for MCI due to AD.
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Affiliation(s)
- William Z Suo
- Laboratory for Alzheimer's Disease & Aging Research, VA Medical Center, Kansas City, MO, USA.,Department of Neurology, University of Kansas Medical Center, Kansas City, KS, USA.,Department of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA.,The University of Kansas Alzheimer's Disease Center, Kansas City, KS, USA
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2
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Speranza L, di Porzio U, Viggiano D, de Donato A, Volpicelli F. Dopamine: The Neuromodulator of Long-Term Synaptic Plasticity, Reward and Movement Control. Cells 2021; 10:735. [PMID: 33810328 PMCID: PMC8066851 DOI: 10.3390/cells10040735] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/20/2021] [Accepted: 03/23/2021] [Indexed: 01/11/2023] Open
Abstract
Dopamine (DA) is a key neurotransmitter involved in multiple physiological functions including motor control, modulation of affective and emotional states, reward mechanisms, reinforcement of behavior, and selected higher cognitive functions. Dysfunction in dopaminergic transmission is recognized as a core alteration in several devastating neurological and psychiatric disorders, including Parkinson's disease (PD), schizophrenia, bipolar disorder, attention deficit hyperactivity disorder (ADHD) and addiction. Here we will discuss the current insights on the role of DA in motor control and reward learning mechanisms and its involvement in the modulation of synaptic dynamics through different pathways. In particular, we will consider the role of DA as neuromodulator of two forms of synaptic plasticity, known as long-term potentiation (LTP) and long-term depression (LTD) in several cortical and subcortical areas. Finally, we will delineate how the effect of DA on dendritic spines places this molecule at the interface between the motor and the cognitive systems. Specifically, we will be focusing on PD, vascular dementia, and schizophrenia.
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Affiliation(s)
- Luisa Speranza
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA;
| | - Umberto di Porzio
- Institute of Genetics and Biophysics “Adriano Buzzati Traverso”, CNR, 80131 Naples, Italy
| | - Davide Viggiano
- Department of Translational Medical Sciences, Genetic Research Institute “Gaetano Salvatore”, University of Campania “L. Vanvitelli”, IT and Biogem S.c.a.r.l., 83031 Ariano Irpino, Italy; (D.V.); (A.d.D.)
| | - Antonio de Donato
- Department of Translational Medical Sciences, Genetic Research Institute “Gaetano Salvatore”, University of Campania “L. Vanvitelli”, IT and Biogem S.c.a.r.l., 83031 Ariano Irpino, Italy; (D.V.); (A.d.D.)
| | - Floriana Volpicelli
- Department of Pharmacy, School of Medicine and Surgery, University of Naples Federico II, 80131 Naples, Italy;
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3
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Vella SA, Moore CA, Li ZH, Hortua Triana MA, Potapenko E, Moreno SNJ. The role of potassium and host calcium signaling in Toxoplasma gondii egress. Cell Calcium 2021; 94:102337. [PMID: 33524795 DOI: 10.1016/j.ceca.2020.102337] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 01/22/2023]
Abstract
Toxoplasma gondii is an obligate intracellular parasite and replicates inside a parasitophorous vacuole (PV) within the host cell. The membrane of the PV (PVM) contains pores that permits for equilibration of ions and small molecules between the host cytosol and the PV lumen. Ca2+ signaling is universal and both T. gondii and its mammalian host cell utilize Ca2+ signals to stimulate diverse cellular functions. Egress of T. gondii from host cells is an essential step for the infection cycle of T. gondii, and a cytosolic Ca2+ increase initiates a Ca2+ signaling cascade that culminates in the stimulation of motility and egress. In this work we demonstrate that intracellular T. gondii tachyzoites are able to take up Ca2+ from the host cytoplasm during host cell signaling events. Both intracellular and extracellular Ca2+ sources are important in reaching a threshold of parasite cytosolic Ca2+ needed for successful egress. Two peaks of Ca2+ were observed in egressing single parasites with the second peak resulting from Ca2+ entry. We patched infected host cells to allow the delivery of precise concentrations of Ca2+ for the stimulation of motility and egress. Using this approach of patching infected host cells, allowed us to determine that increasing the host cytosolic Ca2+ to a specific concentration can trigger egress, which is further accelerated by diminishing the concentration of potassium (K+).
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Affiliation(s)
- Stephen A Vella
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States; Department of Microbiology, University of Georgia, United States
| | - Christina A Moore
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States; Department of Cellular Biology, University of Georgia, Athens, GA, 30602, United States
| | - Zhu-Hong Li
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States
| | | | - Evgeniy Potapenko
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, United States; Department of Cellular Biology, University of Georgia, Athens, GA, 30602, United States.
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4
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Gurevich EV, Gurevich VV. GRKs as Modulators of Neurotransmitter Receptors. Cells 2020; 10:cells10010052. [PMID: 33396400 PMCID: PMC7823573 DOI: 10.3390/cells10010052] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 01/08/2023] Open
Abstract
Many receptors for neurotransmitters, such as dopamine, norepinephrine, acetylcholine, and neuropeptides, belong to the superfamily of G protein-coupled receptors (GPCRs). A general model posits that GPCRs undergo two-step homologous desensitization: the active receptor is phosphorylated by kinases of the G protein-coupled receptor kinase (GRK) family, whereupon arrestin proteins specifically bind active phosphorylated receptors, shutting down G protein-mediated signaling, facilitating receptor internalization, and initiating distinct signaling pathways via arrestin-based scaffolding. Here, we review the mechanisms of GRK-dependent regulation of neurotransmitter receptors, focusing on the diverse modes of GRK-mediated phosphorylation of receptor subtypes. The immediate signaling consequences of GRK-mediated receptor phosphorylation, such as arrestin recruitment, desensitization, and internalization/resensitization, are equally diverse, depending not only on the receptor subtype but also on phosphorylation by GRKs of select receptor residues. We discuss the signaling outcome as well as the biological and behavioral consequences of the GRK-dependent phosphorylation of neurotransmitter receptors where known.
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5
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Beta-adrenergic and M-cholinergic receptor interactions characteristics in the pathogenesis of bronchial obstructive pulmonary diseases. КЛИНИЧЕСКАЯ ПРАКТИКА 2020. [DOI: 10.17816/clinpract35134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Crosstalk between beta-2-adrenoceptor and M- cholinoreceptors in the airway plays one of the main role in the pathogenesis of bronchoobstructive diseases. The interaction of M3-cholinergic receptors and beta2-receptors in the lungs can be characterized as functional antagonism. M3 activation can lead to desensitization of beta2 receptors. Beta2 receptors also limit the action of M3 receptors in various ways. In this case, M2 cholinergic receptors act as autoreceptors. On the one hand, they limit bronchoconstriction caused by a change in the conformation of the M3 cholinergic receptor, and on the other hand, they are able to suppress the excessive bronchorelaxating effect that occurs when beta2 receptor is activated. Knowledge of the crosstalk mechanisms can help to understanad the pathogenesis of bronchial obstructive diseases, optimize existing treatment regimens for chronic obstructive disease (COPD) and bronchial asthma (BA)
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6
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Lee D, Hong JH. Physiological application of nanoparticles in calcium-related proteins and channels. Nanomedicine (Lond) 2019; 14:2479-2486. [PMID: 31456482 DOI: 10.2217/nnm-2019-0004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nanoparticles (NPs) have been studied as therapeutic drug-delivery agents for promising clinical trial outcomes. Nanomaterial-based drugs can transfer conventional drugs to target lesions, such as tumors, with increasing efficiency by enhancing drug-cell interaction or drug absorption. Although they are favorable as efficient drug transfer systems, NPs also exhibit cytotoxicity that affects nonpathological regions. Here, we review the basic information behind NP-induced Ca2+ signaling and its participation in channel physiology and pathology. NPs are observed to demonstrate inhibitory or active effects on Ca2+ signaling. Thus, understanding Ca2+ signaling by NPs as a key mechanism in signal transduction will progress the application of nano-drugs in various diseases without deleterious effect.
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Affiliation(s)
- Dongun Lee
- Department of Physiology, Lee Gil Ya Cancer & Diabetes Institute, College of Medicine, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, South Korea
| | - Jeong Hee Hong
- Department of Physiology, Lee Gil Ya Cancer & Diabetes Institute, College of Medicine, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, South Korea
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Lee NR, Gujarathi S, Bommagani S, Siripurapu K, Zheng G, Dwoskin LP. Muscarinic agonist, (±)-quinuclidin-3-yl-(4-fluorophenethyl)(phenyl)carbamate: High affinity, but low subtype selectivity for human M 1 - M 5 muscarinic acetylcholine receptors. Bioorg Med Chem Lett 2019; 29:471-476. [PMID: 30554957 PMCID: PMC7160324 DOI: 10.1016/j.bmcl.2018.12.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 11/21/2018] [Accepted: 12/10/2018] [Indexed: 11/21/2022]
Abstract
Novel quinuclidinyl N-phenylcarbamate analogs were synthesized, and binding affinities at M1-M5 muscarinic acetylcholine receptor (mAChR) subtypes were determined using Chinese hamster ovary (CHO) cell membranes stably expressing one specific subtype of human mAChR. Although not subtype selective, the lead analog (±)-quinuclidin-3-yl-(4-fluorophenethyl)(phenyl)carbamate (3c) exhibited the highest affinity (Ki = 2.0, 13, 2.6, 2.2, 1.8 nM) at each of the M1-M5 mAChRs, respectively. Based on results from the [3H]dopamine release assay using rat striatal slices, 3c acted as an agonist at mAChRs. The effect of 3c was inhibited by the nonselective mAChR antagonist, scopolamine, and 3c augmented release evoked by oxotremorine. A potent analog from the same scaffold, (±)-quinuclidin-3-yl-(4-methoxyphenethyl)(phenyl)-carbamate (3b) exhibited the greatest selectivity (17-fold) at M3 over M2 mAChRs. These analogs could serve as leads for further discovery of novel subtype-selective muscarinic ligands with the goal of providing therapeutics for substance use disorders and chronic obstructive pulmonary disease.
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Affiliation(s)
- Na-Ra Lee
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, United States
| | - Satheesh Gujarathi
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States
| | - Shobanbabu Bommagani
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States
| | - Kiranbabu Siripurapu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, United States
| | - Guangrong Zheng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States
| | - Linda P Dwoskin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, United States.
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8
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Niu B, Liu P, Shen M, Liu C, Wang L, Wang F, Ma L. GRK5 Regulates Social Behavior Via Suppression of mTORC1 Signaling in Medial Prefrontal Cortex. Cereb Cortex 2017; 28:421-432. [DOI: 10.1093/cercor/bhw364] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 11/01/2016] [Indexed: 01/28/2023] Open
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9
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Santulli G, Iaccarino G. Adrenergic signaling in heart failure and cardiovascular aging. Maturitas 2016; 93:65-72. [PMID: 27062709 PMCID: PMC5036981 DOI: 10.1016/j.maturitas.2016.03.022] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 03/23/2016] [Accepted: 03/25/2016] [Indexed: 12/15/2022]
Abstract
Both cardiovascular disease and aging are associated with changes in the sympathetic nervous system. Indeed, mounting evidence indicates that adrenergic receptors are functionally involved in numerous processes underlying both aging and cardiovascular disorders, in particular heart failure. This article will review the pathophysiological role of the sympathetic nervous system in heart failure and cardiovascular aging.
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Affiliation(s)
- Gaetano Santulli
- College of Physicians & Surgeons, Columbia University Medical Center, New York, NY, USA.
| | - Guido Iaccarino
- Division of Internal Medicine, Department of Medicine and Surgery, University of Salerno, Italy.
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10
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Pera T, Penn RB. Crosstalk between beta-2-adrenoceptor and muscarinic acetylcholine receptors in the airway. Curr Opin Pharmacol 2014; 16:72-81. [PMID: 24747364 DOI: 10.1016/j.coph.2014.03.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 03/17/2014] [Accepted: 03/21/2014] [Indexed: 01/12/2023]
Abstract
The M3 and M2 muscarinic acetylcholine receptors (mAChRs) and beta-2-adrenoceptors (β2ARs) are important regulators of airway cell function, and drugs targeting these receptors are among the first line drugs in the treatment of the obstructive lung diseases asthma and chronic obstructive lung disease (COPD). Cross-regulation or crosstalk between mAChRs and β2ARs in airway smooth muscle (ASM) helps determine the contractile state of the muscle, thus airway diameter and resistance to airflow. In this review we will detail mAChR and β2AR-signaling and crosstalk, focusing on events in the ASM cell but also addressing the function of these receptors in other cell types that impact airway physiology. We conclude by discussing how recent advances in GPCR pharmacology offer a unique opportunity to fine tune mAChR and β2AR signaling and their crosstalk, and thereby produce superior therapeutics for obstructive lung and other diseases.
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Affiliation(s)
- Tonio Pera
- Center for Translational Medicine, Jefferson-Jane and Leonard Korman Lung Center, Department of Medicine, Division of Pulmonary and Critical Care Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Raymond B Penn
- Center for Translational Medicine, Jefferson-Jane and Leonard Korman Lung Center, Department of Medicine, Division of Pulmonary and Critical Care Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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11
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Santulli G, Trimarco B, Iaccarino G. G-protein-coupled receptor kinase 2 and hypertension: molecular insights and pathophysiological mechanisms. High Blood Press Cardiovasc Prev 2013; 20:5-12. [PMID: 23532739 DOI: 10.1007/s40292-013-0001-8] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 11/06/2012] [Indexed: 12/17/2022] Open
Abstract
Numerous factors partake in the fine-tuning of arterial blood pressure. The heptahelical G-protein-coupled receptors (GPCRs) represent one of the largest classes of cell-surface receptors. Further, ligands directed at GPCRs account for nearly 30 % of current clinical pharmaceutical agents available. Given the wide variety of GPCRs involved in blood pressure control, it is reasonable to speculate for a potential role of established intermediaries involved in the GPCR desensitization process, like the G-protein-coupled receptor kinases (GRKs), in the regulation of vascular tone. Of the seven mammalian GRKs, GRK2 seems to be the most relevant isoform at the cardiovascular level. This review attempts to assemble the currently available information concerning GRK2 and hypertension, opening new potential fields of translational investigation to treat this vexing disease.
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Affiliation(s)
- Gaetano Santulli
- Department of Advanced Biomedical Sciences, Federico II University of Naples, 80131, Naples, Italy.
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12
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Suo WZ. Accelerating Alzheimer’s pathogenesis by GRK5 deficiency via cholinergic dysfunction. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/aad.2013.24020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Haack KKV, Engler CW, Papoutsi E, Pipinos II, Patel KP, Zucker IH. Parallel changes in neuronal AT1R and GRK5 expression following exercise training in heart failure. Hypertension 2012; 60:354-61. [PMID: 22753221 DOI: 10.1161/hypertensionaha.112.195693] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although exercise training (ExT) is an important therapeutic strategy for improving quality of life in patients with chronic heart failure (CHF), the central mechanisms by which ExT is beneficial are not well understood. The angiotensin II type 1 receptor (AT1R) plays a pivotal role in the development of CHF and is upregulated in a number of tissues owing, in part, to transcription factor nuclear factor kappa B (NF-κB). In addition, AT1R is marked for internalization and recycling via G-protein-coupled receptor kinase (GRK) phosphorylation. Because previous studies have shown that the beneficial effects of ExT in CHF rely on a reduction in angiotensin II, we hypothesized ExT would decrease AT1R, GRK5, and NF-κB protein expression in the paraventricular nucleus and rostral ventrolateral medulla of CHF rats. Following infarction by coronary artery ligation, animals were exercised 4 weeks postsurgery on a treadmill at a final speed of 25 miles per minute for 60 minutes, 5 days per week for 6 weeks. Western blot analysis of paraventricular nucleus and rostral ventrolateral medulla micropunches revealed an upregulation of AT1R, GRK5, and NF-κB in the infarcted group that was reversed by ExT. Furthermore, the relative expression of phosphorylated AT1R and AT1R/GRK5 physical association was increased in the CHF sedentary group and reversed by ExT. Overexpression of GRK5 in cultured CATH.a neurons blunted angiotensin II-mediated upregulation of AT1R and NF-κB; conversely, silencing of GRK5 exacerbated angiotensin II-mediated AT1R and NF-κB upregulation. Taken together, increased GRK5 may regulate AT1R expression in CHF, and ExT mitigates AT1R and its pathway components.
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Affiliation(s)
- Karla K V Haack
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA
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Dontigny E, Patenaude C, Cyr M, Massicotte G. Sphingomyelinase selectively reduces M1 muscarinic receptors in rat hippocampal membranes. Hippocampus 2012; 22:1589-96. [PMID: 22228652 DOI: 10.1002/hipo.21001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2011] [Indexed: 01/20/2023]
Abstract
Although there is evidence that nicotinic acetylcholine (Ach) receptors are influenced by ceramides, we do not currently know whether or not these sphingolipids can also regulate the muscarinic subtypes of Ach receptors. Using the whole-cell patch technique, we demonstrated that the effectiveness of the muscarinic receptor agonist pilocarpine, in enhancing spontaneous inhibitory postsynaptic currents in CA1 pyramidal cells, was completely abolished in hippocampal slices pre-exposed to the ceramide-generating enzyme sphingomyelinase (SMase). Western blot experiments, performed with biotinylated hippocampal membranes, showed that this electrophysiological defect possibly relies on the loss of M1 muscarinic Ach receptors at the cell surface. However, the effect appears to be relatively specific as the cell-surface expression of M4 muscarinic receptors was not found to be impacted by SMase treatment. Interestingly, we observed that G protein-coupled receptor kinases 2 and β-arrestin1/2 interactions with M1-immunoprecipitated proteins were substantially augmented in SMase-treated slices and that the reduction of cell-surface M1 muscarinic receptor expression generated was completely suppressed by the muscarinic antagonist atropine. Collectively, our data suggest that selective internalization of M1 muscarinic receptors can be accentuated in neurons subjected to high ceramide levels. The potential physiopathological implications of this finding are presented.
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Affiliation(s)
- Eve Dontigny
- Groupe de recherche en Neuroscience, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
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15
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Chen Y, Wang F, Long H, Chen Y, Wu Z, Ma L. GRK5 promotes F-actin bundling and targets bundles to membrane structures to control neuronal morphogenesis. ACTA ACUST UNITED AC 2011; 194:905-20. [PMID: 21930777 PMCID: PMC3207290 DOI: 10.1083/jcb.201104114] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Neuronal morphogenesis requires extensive membrane remodeling and cytoskeleton dynamics. In this paper, we show that GRK5, a G protein-coupled receptor kinase, is critically involved in neurite outgrowth, dendrite branching, and spine morphogenesis through promotion of filopodial protrusion. Interestingly, GRK5 is not acting as a kinase but rather provides a key link between the plasma membrane and the actin cytoskeleton. GRK5 promoted filamentous actin (F-actin) bundling at the membranes of dynamic neuronal structures by interacting with both F-actin and phosphatidylinositol-4,5-bisphosphate. Moreover, separate domains of GRK5 mediated the coupling of actin cytoskeleton dynamics and membrane remodeling and were required for its effects on neuronal morphogenesis. Accordingly, GRK5 knockout mice exhibited immature spine morphology and deficient learning and memory. Our findings identify GRK5 as a critical mediator of dendritic development and suggest that coordinated actin cytoskeleton and membrane remodeling mediated by bifunctional actin-bundling and membrane-targeting molecules, such as GRK5, is crucial for proper neuronal morphogenesis and the establishment of functional neuronal circuitry.
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Affiliation(s)
- Yuejun Chen
- The State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China
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17
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Abstract
G protein-coupled receptors (GPCRs) represent the largest family of membrane receptors and are responsible for regulating a wide variety of physiological processes. This is accomplished via ligand binding to GPCRs, activating associated heterotrimeric G proteins and intracellular signaling pathways. G protein-coupled receptor kinases (GRKs), in concert with β-arrestins, classically desensitize receptor signal transduction, thus preventing hyperactivation of GPCR second-messenger cascades. As changes in GRK expression have featured prominently in many cardiovascular pathologies, including heart failure, myocardial infarction, hypertension, and cardiac hypertrophy, GRKs have been intensively studied as potential diagnostic or therapeutic targets. Herein, we review our evolving understanding of the role of GRKs in cardiovascular pathophysiology.
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Affiliation(s)
- Stephen L Belmonte
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
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Cheng S, Li L, He S, Liu J, Sun Y, He M, Grasing K, Premont RT, Suo WZ. GRK5 deficiency accelerates {beta}-amyloid accumulation in Tg2576 mice via impaired cholinergic activity. J Biol Chem 2010; 285:41541-8. [PMID: 21041302 PMCID: PMC3009881 DOI: 10.1074/jbc.m110.170894] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 10/24/2010] [Indexed: 12/25/2022] Open
Abstract
Membrane G protein-coupled receptor kinase 5 (GRK5) deficiency is linked to Alzheimer disease, yet its precise roles in the disease pathogenesis remain to be delineated. We have previously demonstrated that GRK5 deficiency selectively impairs desensitization of presynaptic M2 autoreceptors, which causes presynaptic M2 hyperactivity and inhibits acetylcholine release. Here we report that inactivation of one copy of Grk5 gene in transgenic mice overexpressing β-amyloid precursor protein (APP) carrying Swedish mutations (Tg2576 or APPsw) resulted in significantly increased β-amyloid (Aβ) accumulation, including increased Aβ(+) plaque burdens and soluble Aβ in brain lysates and interstitial fluid (ISF). In addition, secreted β-APP fragment (sAPPβ) also increased, whereas full-length APP level did not change, suggesting an alteration in favor of β-amyloidogenic APP processing in these animals. Reversely, perfusion of methoctramine, a selective M2 antagonist, fully corrected the difference between the control and GRK5-deficient APPsw mice for ISF Aβ. In contrast, a cholinesterase inhibitor, eserine, although significantly decreasing the ISF Aβ in both control and GRK5-deficient APPsw mice, failed to correct the difference between them. However, combining eserine with methoctramine additively reduced the ISF Aβ further in both animals. Altogether, these findings indicate that GRK5 deficiency accelerates β-amyloidogenic APP processing and Aβ accumulation in APPsw mice via impaired cholinergic activity and that presynaptic M2 hyperactivity is the specific target for eliminating the pathologic impact of GRK5 deficiency. Moreover, a combination of an M2 antagonist and a cholinesterase inhibitor may reach the maximal disease-modifying effect for both amyloid pathology and cholinergic dysfunction.
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Affiliation(s)
- Shaowu Cheng
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Longxuan Li
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Department of Neurology, Guangdong Medical College Affiliated Hospital, Zhanjiang 524001, China
| | - Shuangteng He
- the Substance Abuse Research Laboratory, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Jun Liu
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Department of Neurology, the Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510120, China
| | - Yuning Sun
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Minchao He
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- The Department of Biochemistry and Molecular Biology, Ningxia Medical University, Yinchuan, Ningxia 750004, China, and
| | - Kenneth Grasing
- the Substance Abuse Research Laboratory, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Richard T. Premont
- the Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710
| | - William Z. Suo
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Departments of Neurology and
- Physiology, University of Kansas Medical College, Kansas City, Kansas 66170
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Nedi T, White PJ, Coupar IM, Irving HR. Tissue dependent differences in G-protein coupled receptor kinases associated with 5-HT4 receptor desensitization in the rat gastro-intestinal tract. Biochem Pharmacol 2010; 81:123-33. [PMID: 20836992 DOI: 10.1016/j.bcp.2010.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 08/31/2010] [Accepted: 09/02/2010] [Indexed: 12/12/2022]
Abstract
Desensitization of 5-HT(4) receptors is regulated by G-protein coupled receptor kinases (GRKs). However, the specific GRK(s) that regulates the desensitization of 5-HT(4) receptors in the in vivo setting is unknown. We investigated the in situ expression of 5-HT(4) receptors and the GRKs in the rat gastrointestinal tract using immunohistochemistry and their interaction using coimmunoprecipitation. 5-HT(4) receptors were expressed in the tunica muscularis mucosae of the oesophagus, longitudinal muscle, myenteric plexus, circular muscle, submucosal plexus and muscularis mucosae of both the proximal and distal colon. GRK2 was expressed in longitudinal muscle and occasionally in myenteric plexus whilst GRK5 showed limited expression in the nerve endings of the myenteric plexus and submucosal plexus of the colon. GRK3 was expressed in the tunica muscularis mucosae of the oesophagus, circular muscle, submucosal plexus and muscularis mucosae of the colon. GRK6 was expressed in the tunica muscularis mucosae of the oesophagus, longitudinal muscle, circular muscle, and muscularis mucosae of the colon. Stimulation of tunica muscularis mucosae of the oesophagus and distal colon using the 5-HT(4) receptor agonist, tegaserod, followed by analysis of the 5-HT(4) receptor antibody immunoprecipitate, revealed the coimmunoprecipitation of GRK6 with 5-HT(4) receptors in the tunica muscularis mucosae of oesophagus while GRK2 and GRK6 were coimmunoprecipitated with 5-HT(4) receptors in the distal colon. This study indicates that GRK6 may be involved in the regulation of the desensitization of 5-HT(4) receptors in the rat oesophagus whilst GRK2 and GRK6 may be involved in regulation of the desensitization of 5-HT(4) receptors in the distal colon.
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Affiliation(s)
- Teshome Nedi
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Vic 3052, Australia
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20
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Pastva AM, Walker JKL, Maddox LA, Mukherjee S, Giamberardino C, Hsia B, Potts E, Zhu H, Degan S, Sunday ME, Lawson BL, Korfhagen TR, Schwartz DA, Eu JP, Foster WM, McMahon TJ, Que L, Wright JR. Nitric oxide mediates relative airway hyporesponsiveness to lipopolysaccharide in surfactant protein A-deficient mice. Am J Respir Cell Mol Biol 2010; 44:175-84. [PMID: 20348208 PMCID: PMC3049231 DOI: 10.1165/rcmb.2009-0284oc] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Surfactant protein A (SP-A) mediates innate immune cell responses to LPS, a cell wall component of gram-negative bacteria that is found ubiquitously in the environment and is associated with adverse health effects. Inhaled LPS induces lung inflammation and increases airway responsiveness (AR). However, the role of SP-A in mediating LPS-induced AR is not well-defined. Nitric oxide (NO) is described as a potent bronchodilator, and previous studies showed that SP-A modulates the LPS-induced production of NO. Hence, we tested the hypothesis that increased AR, observed in response to aerosolized LPS exposure, would be significantly reduced in an SP-A-deficient condition. Wild-type (WT) and SP-A null (SP-A(-/-)) mice were challenged with aerosolized LPS. Results indicate that despite similar inflammatory indices, LPS-treated SP-A(-/-) mice had attenuated AR after methacholine challenge, compared with WT mice. The attenuated AR could not be attributed to inherent differences in SP-D concentrations or airway smooth muscle contractile and relaxation properties, because these measures were similar between WT and SP-A(-/-) mice. LPS-treated SP-A(-/-) mice, however, had elevated nitrite concentrations, inducible nitric oxide synthase (iNOS) expression, and NOS activity in their lungs. Moreover, the administration of the iNOS-specific inhibitor 1400W completely abrogated the attenuated AR. Thus, when exposed to aerosolized LPS, SP-A(-/-) mice demonstrate a relative airway hyporesponsiveness that appears to be mediated at least partly via an iNOS-dependent mechanism. These findings may have clinical significance, because recent studies reported associations between surfactant protein polymorphisms and a variety of lung diseases.
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Affiliation(s)
- Amy M Pastva
- Duke University Medical Center, Durham, NC 27710, USA.
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21
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Molfino NA. Increased vagal airway tone in fatal asthma. Med Hypotheses 2009; 74:521-3. [PMID: 19906493 DOI: 10.1016/j.mehy.2009.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 10/08/2009] [Indexed: 11/18/2022]
Abstract
Slow-onset asthma deaths are characterized by eosinophilic airway infiltrates and thickening of the basal membrane, while rapid-onset asthma deaths are associated with fewer airway inflammatory changes, suggesting that bronchospasm may be responsible for the latter events. Airway tone is primarily controlled by the autonomous nervous system and can be pharmacologically modified. Therapies that stimulate the sympathetic beta(2) adrenoreceptor or inhibit the muscarinic receptor signal transduction induce bronchodilation. Parasympathetic (vagal) airway tone is enhanced in some asthmatics due to a number of stimuli, while in others it is constitutively heightened. Mainstream asthma therapy, however, only consists of corticosteroids and beta(2) agonists, not addressing this aspect. In this publication, I propose that increased vagal airway tone resulting in overwhelming bronchoconstriction and mucus plugging could be responsible for the near-fatal or fatal events observed in a number of asthmatics, in spite of their adequate treatment with standard therapies. On the basis of this hypothesis, I recommend that vagal airway tone be assessed in all patients with asthma, particularly in those with a history of near-fatal events. If the airway tone is increased, individuals should be treated with a triple combination of long-acting beta(2) agonists, inhaled steroids, and inhaled anticholinergics to prevent vagally mediated fatal events.
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Affiliation(s)
- Nestor A Molfino
- MedImmune, LLC, Clinical Development, One MedImmune Way, Office # 45C20, Gaithersburg, MD 20854, USA.
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22
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Targeted transgenesis reveals discrete attenuator functions of GRK and PKA in airway beta2-adrenergic receptor physiologic signaling. Proc Natl Acad Sci U S A 2009; 106:15007-12. [PMID: 19706446 DOI: 10.1073/pnas.0906034106] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Phosphorylation by protein kinase A (PKA) and G protein-coupled receptor kinases (GRKs) desensitize beta2-adrenergic receptor (beta2AR) signaling, and these are thought to be mechanisms involved with cell and organ homeostasis and tolerance to agonists. However, there is little direct evidence that these events are relevant to beta2AR physiological function, such as airway smooth muscle (ASM) relaxation leading to bronchodilation. To maintain cell- and receptor-specificity without altering the natural complement of kinases/arrestins, transgenic mice were generated expressing the human WT and mutated beta2ARs lacking PKA and/or GRK phosphorylation sites on ASM at approximately 4-fold over background. Functional gains in response to beta-agonist from the selective loss of these mechanisms were determined in mouse airways. Relaxation kinetics were altered in all mutant airways compared with beta2WT. At low receptor occupancy, beta2PKA(-) had enhanced agonist-promoted relaxation, while beta2GRK(-) airways were unaffected. In contrast, at saturating agonist concentrations, the greatest relaxation enhancement was with beta2GRK(-), with no evidence for additivity when PKA sites were also removed. For the full range of responses, the beta2PKA(-)/GRK(-) airways had the greatest relaxation efficiency, indicating a graded effect of GRKs as agonist concentration increased. ASM cAMP levels paralleled relaxation phenotypes. No interaction between PKA phosphorylation of beta2AR and GRK-promoted events was identified by beta-arrestin-2 recruitment. Thus, these two mechanisms indeed impact a relevant beta2AR physiologic function, acting as attenuators of the acute response, and represent specific interfaces where adjunct therapy or biased ligands may improve beta-agonist treatment of obstructive lung disease.
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Liu J, Rasul I, Sun Y, Wu G, Li L, Premont RT, Suo WZ. GRK5 deficiency leads to reduced hippocampal acetylcholine level via impaired presynaptic M2/M4 autoreceptor desensitization. J Biol Chem 2009; 284:19564-71. [PMID: 19478075 PMCID: PMC2740582 DOI: 10.1074/jbc.m109.005959] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptor kinase 5 (GRK5) deficiency has been linked recently to early Alzheimer disease (AD), but the mechanism by which GRK5 deficiency may contribute to AD pathogenesis remains elusive. Here we report that overexpression of dominant negative mutant of GRK5 (dnGRK5) in a cholinergic neuronal cell line led to decreased acetylcholine (ACh) release. This reduction was fully corrected by pertussis toxin, atropine (a nonselective muscarinic antagonist), or methoctramine (a selective M2/M4 muscarinic receptor antagonist). Consistent with results in cultured cells, high potassium-evoked ACh release in hippocampal slices from young GRK5 knock-out mice was significantly reduced compared with wild type littermates, and this reduced ACh release was also fully corrected by methoctramine. In addition, following treatment with the nonselective muscarinic agonist oxotremorine-M, M2, and M4 receptors underwent significantly reduced internalization in GRK5KO slices compared with wild type slices, as assessed by plasma membrane retention of receptor immunoreactivity, whereas M1 receptor internalization was not affected by loss of GRK5 expression. Moreover, Western blotting revealed no synaptic or cholinergic degenerative changes in young GRK5 knock-out mice. Altogether, these results suggest that GRK5 deficiency leads to a reduced hippocampal ACh release and cholinergic hypofunction by selective impairment of desensitization of presynaptic M2/M4 autoreceptors. Because this nonstructural cholinergic hypofunction precedes the hippocampal cholinergic hypofunction associated with structural cholinergic degeneration and cognitive decline in aged GRK5 knock-out mice, this nonstructural alteration may be an early event contributing to cholinergic degeneration in AD.
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Affiliation(s)
- Jun Liu
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Department of Neurology, the Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510120, China
| | - Imtiaz Rasul
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Yuning Sun
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Department of Biochemistry and Molecular Biology, Ningxia Medical University, Yinchuan, Ningxia 750004, China, and
| | - Guisheng Wu
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
| | - Longxuan Li
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Department of Neurology, Guangdong Medical College Affiliated Hospital, Zhanjian, Guangdong 524001, China
| | - Richard T. Premont
- the Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710
| | - William Z. Suo
- From the Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri 64128
- the Departments of Neurology and Physiology, University of Kansas Medical College, Kansas City, Kansas 66170
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24
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GRK mythology: G-protein receptor kinases in cardiovascular disease. J Mol Med (Berl) 2009; 87:455-63. [DOI: 10.1007/s00109-009-0450-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 01/21/2009] [Accepted: 01/26/2009] [Indexed: 01/14/2023]
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25
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Liu J, Li L, Suo WZ. HT22 hippocampal neuronal cell line possesses functional cholinergic properties. Life Sci 2008; 84:267-71. [PMID: 19135458 DOI: 10.1016/j.lfs.2008.12.008] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 11/21/2008] [Accepted: 12/04/2008] [Indexed: 01/20/2023]
Abstract
AIMS Hippocampal cholinergic hypofunction is known to be involved in the cognitive deficits of Alzheimer's disease, but the detailed mechanisms remain to be elucidated. In order to establish an in vitro hippocampal cholinergic neuronal model for the relevant mechanistic studies, we have characterized a widely used hippocampal neuronal cell line, HT22, a sub-line derived from parent HT4 cells that were originally immortalized from primary mouse hippocampal neuronal culture. MAIN METHODS Western blot and immunocytochemistry were used to examine expression of cholinergic markers in HT22 cells. High potassium-evoked [(3)H]ACh release was used to evaluate the cholinergic functional properties of the cells. KEY FINDINGS We found that HT22 cells express essential cholinergic markers, such as the high affinity choline transporter, choline acetyltransferase, vesicular acetylcholine transporter, and muscarinic acetylcholine receptors. Exposure of HT22 cells to high potassium evoked [(3)H]ACh release in a dose-dependent manner. In addition, the [(3)H]ACh release was significantly potentiated when presynaptic autoreceptors were blocked. SIGNIFICANCE Our results suggest that HT22 cells possess functional cholinergic properties, and can be used for an in vitro model for defining the mechanisms in cognitive deficits of Alzheimer's disease.
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Affiliation(s)
- Jun Liu
- Department of Neurology, the Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510120, PR China
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26
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Li L, Rasul I, Liu J, Zhao B, Tang R, Premont RT, Suo WZ. Augmented axonal defects and synaptic degenerative changes in female GRK5 deficient mice. Brain Res Bull 2008; 78:145-51. [PMID: 18955119 DOI: 10.1016/j.brainresbull.2008.09.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 08/08/2008] [Accepted: 09/23/2008] [Indexed: 10/21/2022]
Abstract
Recent studies suggested that G protein-coupled receptor kinase 5 (GRK5) deficiency plays a significant role in early Alzheimer's disease (AD) pathogenesis, and that the GRK5 knockout (GRK5KO) mouse displays an early Alzheimer-like cognitive deficit associated with increased hippocampal axonal defects and synaptic degenerative changes. Gender is known to play a role in AD, with females showing more extensive pathologic changes in brain compared to males. Although GRK5 deficiency is linked to AD, it is unknown whether the pathologic changes solely driven by the GRK5 deficiency are gender-dependent. To determine this, extent of the pathologic changes in aged GRK5KO mice was compared between genders. We find that female GRK5KO mice had a 2.5-fold increase in hippocampal swollen axonal clusters compared to male GRK5KO mice. Moreover, hippocampal levels of several synaptic proteins, including synaptophysin, were significantly lower in the female than the male. In addition, although increased Luteinizing hormone (LH) activity is believed to play a significant role in the gender phenomenon in AD, we found that desensitization of LH receptor is not affected by the GRK5 deficiency. Therefore, the worsened pathologic changes in the female mice cannot be attributed to an impaired LH receptor desensitization. Taken together, this study demonstrates a synergistic interaction between GRK5 deficiency and gender in promoting early AD-like pathologic changes in the female GRK5KO mice, although the underlying molecular mechanisms remain to be elucidated.
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Affiliation(s)
- Longxuan Li
- Lab. for Alzheimer's Disease & Aging Res., VA Med. Center, Kansas City, MO 64128, United States
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27
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Tobin AB, Butcher AJ, Kong KC. Location, location, location...site-specific GPCR phosphorylation offers a mechanism for cell-type-specific signalling. Trends Pharmacol Sci 2008; 29:413-20. [PMID: 18606460 PMCID: PMC2880250 DOI: 10.1016/j.tips.2008.05.006] [Citation(s) in RCA: 236] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 05/14/2008] [Accepted: 05/14/2008] [Indexed: 12/21/2022]
Abstract
It is now established that most of the approximately 800 G-protein-coupled receptors (GPCRs) are regulated by phosphorylation in a process that results in the recruitment of arrestins, leading to receptor desensitization and the activation of arrestin-dependent processes. This generalized view of GPCR regulation, however, does not provide an adequate mechanism for the control of tissue-specific GPCR signalling. Here, we review the evidence that GPCR phosphorylation is, in fact, a flexible and dynamic regulatory process in which GPCRs are phosphorylated in a unique manner that is associated with the cell type in which the receptor is expressed. In this scenario, phosphorylation offers a mechanism of regulating the signalling outcome of GPCRs that can be tailored to meet a specific physiological role.
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Affiliation(s)
- Andrew B Tobin
- Department of Cell Physiology and Pharmacology, University of Leicester, LE1 9HN, UK.
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29
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Sánchez-Mendoza ME, Castillo-Henkel C, Navarrete A. Relaxant action mechanism of berberine identified as the active principle of Argemone ochroleuca Sweet in guinea-pig tracheal smooth muscle. J Pharm Pharmacol 2008; 60:229-36. [PMID: 18237471 DOI: 10.1211/jpp.60.2.0012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
In this study we investigated the relaxant effect of the aerial parts of Argemone ochroleuca (Papaveraceae), which is used in Mexican traditional medicine for the treatment of various respiratory diseases such as cough, bronchitis and asthma. The alkaloid berberine was identified as one of the active relaxant principles (EC50 = 118.50 +/-3.91 microM) in the dichloromethane extract of A. ochroleuca (EC50 = 78.03 +/- 2.15 microg mL(-1) with 95.12 +/- 3.56% of relaxation). Berberine concentration-dependently relaxed the carbachol-induced precontractions but not histamine- or KCl-induced precontraction. The relaxant effect of berberine was unaffected by the presence of propranolol (3 microM), glibenclamide (10 microM) or ODQ (10microM). However, 2', 5'-dideoxyadenosine (10 microM) blocked the log concentration-response curves of berberine. On the other hand, berberine produced a leftward shift of the log concentration-response curves of isoproterenol, forskolin and nitroprusside. Additionally, berberine produced a parallel rightward shift of the concentration-response curve of carbachol in a competitive manner with a pA2 of 3.87 +/- 0.045. The above results suggest that the relaxant effect of berberine on tracheal muscle is due to its antagonistic effect on muscarinic acetylcholine receptors.
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Affiliation(s)
- María Elena Sánchez-Mendoza
- Facultad de Química, Departamento de Farmacia, Universidad Nacional Autónoma de México, México D.F., 04510, México
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30
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Torrecilla I, Spragg EJ, Poulin B, McWilliams PJ, Mistry SC, Blaukat A, Tobin AB. Phosphorylation and regulation of a G protein-coupled receptor by protein kinase CK2. ACTA ACUST UNITED AC 2007; 177:127-37. [PMID: 17403928 PMCID: PMC2064117 DOI: 10.1083/jcb.200610018] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We demonstrate a role for protein kinase casein kinase 2 (CK2) in the phosphorylation and regulation of the M3-muscarinic receptor in transfected cells and cerebellar granule neurons. On agonist occupation, specific subsets of receptor phosphoacceptor sites (which include the SASSDEED motif in the third intracellular loop) are phosphorylated by CK2. Receptor phosphorylation mediated by CK2 specifically regulates receptor coupling to the Jun-kinase pathway. Importantly, other phosphorylation-dependent receptor processes are regulated by kinases distinct from CK2. We conclude that G protein–coupled receptors (GPCRs) can be phosphorylated in an agonist-dependent fashion by protein kinases from a diverse range of kinase families, not just the GPCR kinases, and that receptor phosphorylation by a defined kinase determines a specific signalling outcome. Furthermore, we demonstrate that the M3-muscarinic receptor can be differentially phosphorylated in different cell types, indicating that phosphorylation is a flexible regulatory process where the sites that are phosphorylated, and hence the signalling outcome, are dependent on the cell type in which the receptor is expressed.
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Affiliation(s)
- Ignacio Torrecilla
- Department of Cell Physiology and Pharmacology and Protein and Nucleic Acid Chemistry Laboratory, University of Leicester, Leicester LE1 9HN, England, UK
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31
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Abstract
Heterotrimeric G protein-coupled receptors (GPCRs) are found on the surface of all cells of multicellular organisms and are major mediators of intercellular communication. More than 800 distinct GPCRs are present in the human genome, and individual receptor subtypes respond to hormones, neurotransmitters, chemokines, odorants, or tastants. GPCRs represent the most widely targeted pharmacological protein class. Because drugs that target GPCRs often engage receptor regulatory mechanisms that limit drug effectiveness, particularly in chronic treatment, there is great interest in understanding how GPCRs are regulated, as a basis for designing therapeutic drugs that evade this regulation. The major GPCR regulatory pathway involves phosphorylation of activated receptors by G protein-coupled receptor kinases (GRKs), followed by binding of arrestin proteins, which prevent receptors from activating downstream heterotrimeric G protein pathways while allowing activation of arrestin-dependent signaling pathways. Although the general mechanisms of GRK-arrestin regulation have been well explored in model cell systems and with purified proteins, much less is known about the role of GRK-arrestin regulation of receptors in physiological and pathophysiological settings. This review focuses on the physiological functions and potential pathophysiological roles of GRKs and arrestins in human disorders as well as on recent studies using knockout and transgenic mice to explore the role of GRK-arrestin regulation of GPCRs in vivo.
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Affiliation(s)
- Richard T Premont
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Rossi JL, Velentza AV, Steinhorn DM, Watterson DM, Wainwright MS. MLCK210 gene knockout or kinase inhibition preserves lung function following endotoxin-induced lung injury in mice. Am J Physiol Lung Cell Mol Physiol 2007; 292:L1327-34. [PMID: 17307813 DOI: 10.1152/ajplung.00380.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Barrier dysfunction, involving the endothelium or epithelium, is implicated in the pathophysiology of many disease states, including acute and ventilator-associated lung injury. Evidence from cell culture, in vivo and clinical studies, has identified myosin light chain kinase as a drug discovery target for such diseases. Here, we measured disease-relevant end points to test the hypothesis that inhibition of myosin light chain kinase is a potential therapeutic target for treatment of barrier dysfunction resulting from acute lung injury. We used a combined gene knockout and chemical biology approach with an in vivo intact lung injury model. We showed that inhibition of myosin light chain kinase protects lung function, preserves oxygenation, prevents acidosis, and enhances survival after endotoxin exposure with subsequent mechanical ventilation. This protective effect provided by the small molecule inhibitor of myosin light chain kinase is present when the inhibitor is administered during a clinically relevant injury paradigm after endotoxin exposure. Treatment with inhibitor confers additional protection against acute lung injury to that provided by a standard protective mode of ventilation. These results support the hypothesis that myosin light chain kinase is a potential therapeutic target for acute lung injury and provide clinical end points of arterial blood gases and pulmonary compliance that facilitate the direct extrapolation of these studies to measures used in critical care medicine.
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Affiliation(s)
- Janet L Rossi
- Center for Drug Discovery and Chemical Biology, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Northwestern Univ., 303 E. Chicago Ave., Ward 8-196, Chicago, IL 60611, USA.
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De Lorme KC, Sikorski KL, Grant MKO, El-Fakahany EE. Long-term wash-resistant effects of brief interaction of xanomeline at the M1 muscarinic receptor. Neurosci Lett 2006; 410:11-4. [PMID: 17052840 PMCID: PMC1850384 DOI: 10.1016/j.neulet.2006.09.062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 09/21/2006] [Accepted: 09/23/2006] [Indexed: 11/28/2022]
Abstract
Compared to other M(1) muscarinic acetylcholine receptor (M(1) mAChR) agonists, xanomeline demonstrates both reversible and persistent modes of binding to the receptor. In our study, we investigated the long-term consequences of brief incubation of Chinese hamster ovary cells expressing M(1) mAChR (M(1)-CHO) with low concentrations of xanomeline followed by washing off the free drug. Thus, M(1)-CHO cells were exposed to 100 nM xanomeline for 1h then washed extensively. Washed cells were either used immediately for binding assays or incubated for 23 h in the absence of free xanomeline. Only the latter treatment conditions resulted in marked attenuation of binding of the muscarinic radioligand [(3)H]N-methylscopolamine ([(3)H]NMS) to intact cells. Shortening the xanomeline pretreatment period to 1 min had the same trends as the 1h pretreatment, implying that xanomeline binds instantly to the receptor to elicit long-term wash-resistant effects. Presence of atropine during the brief period of xanomeline pretreatment did not markedly modulate xanomeline's long-term effects, which suggests that persistent anchoring of the xanomeline molecule to the M(1) receptor takes place at a site distinct from the orthosteric binding domain. Our findings suggest the possibility of a time-dependent transition of the conformation of the muscarinic M(1) receptor-xanomeline complex between states that vary in their ability to bind [(3)H]NMS. However, possible involvement of other mechanisms of long-term receptor regulation cannot be discounted.
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Affiliation(s)
- Kayla C De Lorme
- Division of Neuroscience Research in Psychiatry, University of Minnesota Medical School, Mayo Mail Code 392, 420 Delaware St. SE, Minneapolis, MN 55455, USA
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34
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Suo Z, Cox AA, Bartelli N, Rasul I, Festoff BW, Premont RT, Arendash GW. GRK5 deficiency leads to early Alzheimer-like pathology and working memory impairment. Neurobiol Aging 2006; 28:1873-88. [PMID: 17011668 DOI: 10.1016/j.neurobiolaging.2006.08.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 08/25/2006] [Accepted: 08/29/2006] [Indexed: 11/29/2022]
Abstract
G-protein coupled receptor kinase-5 (GRK5) deficiency has been linked to early Alzheimer's disease in humans and mouse models of the disease. To determine potential roles of GRK5 in the disease pathogenesis, the GRK5 knockout mouse was evaluated at pathological and behavioral levels. We found that these mice displayed an age-dependent increase in hippocampal axonal defects characterized by clusters of axonal swellings that accumulated abnormal amounts of molecular motor proteins, microtubule-associated proteins, intracellular beta-amyloid, and subcellular organelles. In severe cases, extracellular beta-amyloid fibrillar deposits were occasionally observed, along with degenerating axonal components, and were tightly surrounded by reactive astrocytes. Moreover, significant loss of synaptic proteins and early signs of cholinoceptive neurodegeneration were evident in the hippocampus as well. Consistent with the moderate level of pathologic change, aged GRK5 knockout mice displayed selective working memory impairment, with other cognitive domains unaffected. Taken together, these findings not only strongly support an important role of GRK5 deficiency in early Alzheimer's pathogenesis, but also promote the GRK5 knockout mouse as an additional model for early Alzheimer-related studies.
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Affiliation(s)
- Zhiming Suo
- Laboratory for Alzheimer's Disease & Aging Research, Veterans Affairs Medical Center, Kansas City, MO 64128, USA.
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35
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Matkovich SJ, Diwan A, Klanke JL, Hammer DJ, Marreez Y, Odley AM, Brunskill EW, Koch WJ, Schwartz RJ, Dorn GW. Cardiac-specific ablation of G-protein receptor kinase 2 redefines its roles in heart development and beta-adrenergic signaling. Circ Res 2006; 99:996-1003. [PMID: 17008600 DOI: 10.1161/01.res.0000247932.71270.2c] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
G-protein receptor kinase 2 (GRK2) is 1 of 7 mammalian GRKs that phosphorylate ligand-bound 7-transmembrane receptors, causing receptor uncoupling from G proteins and potentially activating non-G-protein signaling pathways. GRK2 is unique among members of the GRK family in that its genetic ablation causes embryonic lethality. Cardiac abnormalities in GRK2 null embryos implicated GRK2 in cardiac development but prevented studies of the knockout phenotype in adult hearts. Here, we created GRK2-loxP-targeted mice and used Cre recombination to generate germline and cardiac-specific GRK2 knockouts. GRK2 deletion in the preimplantation embryo with EIIa-Cre (germline null) resulted in developmental retardation and embryonic lethality between embryonic day 10.5 (E10.5) and E11.5. At E9.5, cardiac myocyte specification and cardiac looping were normal, but ventricular development was delayed. Cardiomyocyte-specific ablation of GRK2 in the embryo with Nkx2.5-driven Cre (cardiac-specific GRK2 knockout) produced viable mice with normal heart structure, function, and cardiac gene expression. Cardiac-specific GRK2 knockout mice exhibited enhanced inotropic sensitivity to the beta-adrenergic receptor agonist isoproterenol, with impairment of normal inotropic and lusitropic tachyphylaxis, and exhibited accelerated development of catecholamine toxicity with chronic isoproterenol treatment. These findings show that cardiomyocyte autonomous GRK2 is not essential for myocardial development after cardiac specification, suggesting that embryonic developmental abnormalities may be attributable to extracardiac effects of GRK2 ablation. In the adult heart, cardiac GRK2 is a major factor regulating inotropic and lusitropic tachyphylaxis to beta-adrenergic agonist, which likely contributes to its protective effects in catecholamine cardiomyopathy.
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Affiliation(s)
- Scot J Matkovich
- Center for Molecular Cardiovascular Research, University of Cincinnati, Ohio, USA
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Halayko AJ, Stelmack GL. The association of caveolae, actin, and the dystrophin-glycoprotein complex: a role in smooth muscle phenotype and function? Can J Physiol Pharmacol 2006; 83:877-91. [PMID: 16333360 DOI: 10.1139/y05-107] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Smooth muscle cells exhibit phenotypic and mechanical plasticity. During maturation, signalling pathways controlling actin dynamics modulate contractile apparatus-associated gene transcription and contractile apparatus remodelling resulting from length change. Differentiated myocytes accumulate abundant caveolae that evolve from the structural association of lipid rafts with caveolin-1, a protein with domains that confer unique functional properties. Caveolae and caveolin-1 modulate and participate in receptor-mediated signalling, and thus contribute to functional diversity of phenotypically similar myocytes. In mature smooth muscle, caveolae are partitioned into discrete linear domains aligned with structural proteins that tether actin to the extracellular matrix. Caveolin-1 binds with beta-dystroglycan, a subunit of the dystrophin glycoprotein complex (DGC), and with filamin, an actin binding protein that organizes cortical actin, to which integrins and focal adhesion complexes are anchored. The DGC is linked to the actin cytoskeleton by a dystrophin subunit and is a receptor for extracellular laminin. Thus, caveolae and caveolin-associated signalling proteins and receptors are linked via structural proteins to a dynamic filamentous actin network. Despite development of transgenic models to investigate caveolins and membrane-associated actin-linking proteins in skeletal and cardiac muscle function, only superficial understanding of this association in smooth muscle phenotype and function has emerged.
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Affiliation(s)
- Andrew J Halayko
- Department of Physiology, University of Manitoba, Winnipeg, Canada.
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Premont RT. Once and future signaling: G protein-coupled receptor kinase control of neuronal sensitivity. Neuromolecular Med 2005; 7:129-47. [PMID: 16052042 DOI: 10.1385/nmm:7:1-2:129] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Accepted: 03/02/2005] [Indexed: 12/22/2022]
Abstract
G protein-coupled receptors (GPCRs) are the most numerous class of cell surface receptor, and substances acting through GPCRs mediate many critical signaling events and physiological processes. GPCR sensitivity and signaling is dynamic, responding rapidly to adjust to changes in the ambient level of stimulation of target cells. One important mediator of such receptor sensitivity is the family of GPCR kinases (GRKs). Like heterotrimeric G proteins, GRKs recognize agonist-bound, activated receptors, and this recognition promotes catalytic activation of GRKs, resulting in the preferential phosphorylation of activated receptors. GRK-phosphorylated receptors are then targeted by arrestin proteins, which bind to phosphorylated receptors. Arrestin-bound receptors are uncoupled from heterotrimeric G proteins, resulting in decreased sensitivity to further receptor stimulation (desensitization). Arrestin-bound receptors are also accelerated into internalization pathways and linked to distinct arrestin-mediated signaling pathways. GRKs thus serve as gatekeepers for receptors, terminating some signaling pathways and initiating others. One major outstanding question concerning GRKs understanding the mechanisms by which any particular receptor subtype (of the 800 or so in the body) is regulated by a specific GRK(s), and the consequences of this specificity. An understanding of this regulatory specificity could allow targeting of GRK function to ameliorate diseases involving GPCR dysregulation.
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Affiliation(s)
- Richard T Premont
- Liver Center, Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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Feldman DS, Carnes CA, Abraham WT, Bristow MR. Mechanisms of disease: beta-adrenergic receptors--alterations in signal transduction and pharmacogenomics in heart failure. ACTA ACUST UNITED AC 2005; 2:475-83. [PMID: 16265588 DOI: 10.1038/ncpcardio0309] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 06/23/2005] [Indexed: 01/08/2023]
Abstract
Beta-adrenergic signaling is an important regulator of myocardial function. During the progression of heart failure (HF), a reproducible series of biochemical events occurs that affects beta-adrenergic receptor (beta-AR) signaling and cardiac function. Furthermore, there are pathophysiologic alterations in the expression and regulation of proteins that are regulated by beta-ARs during HF. Analyses of these complex signaling pathways have led to a better understanding of HF mechanisms and the use of beta-adrenergic antagonists, which have notably altered HF-related morbidity and mortality. Despite therapeutic advances that have affected beta-AR signaling, HF remains a leading cause of hospitalization and a principal cause of death in industrialized nations. In this review, we summarize current insights into beta-adrenergic signal-transduction pathways, the best-described beta-AR polymorphisms, and therapies that target the beta-AR pathway in HF.
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Affiliation(s)
- David S Feldman
- Davis Heart and Lung Research Institute, Division of Cardiology/Medicine, Ohio State University, Columbus, OH 43210, USA.
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Hu P, Greenwood CMT, Beyene J. Integrative analysis of multiple gene expression profiles with quality-adjusted effect size models. BMC Bioinformatics 2005; 6:128. [PMID: 15921507 PMCID: PMC1173085 DOI: 10.1186/1471-2105-6-128] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Accepted: 05/27/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND With the explosion of microarray studies, an enormous amount of data is being produced. Systematic integration of gene expression data from different sources increases statistical power of detecting differentially expressed genes and allows assessment of heterogeneity. The challenge, however, is in designing and implementing efficient analytic methodologies for combination of data generated by different research groups. RESULTS We extended traditional effect size models to combine information from different microarray datasets by incorporating a quality measure for each gene in each study into the effect size estimation. We illustrated our method by integrating two datasets generated using different Affymetrix oligonucleotide types. Our results indicate that the proposed quality-adjusted weighting strategy for modelling inter-study variation of gene expression profiles not only increases consistency and decreases heterogeneous results between these two datasets, but also identifies many more differentially expressed genes than methods proposed previously. CONCLUSION Data integration and synthesis is becoming increasingly important. We live in a high-throughput era where technologies constantly change leaving behind a trail of data with different forms, shapes and sizes. Statistical and computational methodologies are therefore critical for extracting the most out of these related but not identical sources of data.
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Affiliation(s)
- Pingzhao Hu
- The Hospital for Sick Children Research Institute, 555 University Ave., Toronto, ON, M5G 1X8, Canada
| | - Celia MT Greenwood
- The Hospital for Sick Children Research Institute, 555 University Ave., Toronto, ON, M5G 1X8, Canada
- Department of Public Health Sciences, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
| | - Joseph Beyene
- The Hospital for Sick Children Research Institute, 555 University Ave., Toronto, ON, M5G 1X8, Canada
- Department of Public Health Sciences, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
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Raehal KM, Walker JKL, Bohn LM. Morphine side effects in beta-arrestin 2 knockout mice. J Pharmacol Exp Ther 2005; 314:1195-201. [PMID: 15917400 DOI: 10.1124/jpet.105.087254] [Citation(s) in RCA: 450] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Morphine is a potent analgesic, yet, like most opioid narcotics, it exerts unwanted side effects such as constipation and respiratory suppression, thereby limiting its clinical utility. Pharmacological approaches taken to preserve the analgesic properties, while eliminating the unwanted side effects, have met with very limited success. Here, we provide evidence that altering mu opioid receptor regulation may provide a novel approach to discriminate morphine's beneficial and deleterious effects in vivo. We have previously reported that mice lacking the G protein-coupled receptor regulatory protein, beta-arrestin 2, display profoundly altered morphine responses. beta-Arrestin 2 knockout mice have enhanced and prolonged morphine analgesia with very little morphine tolerance. In this report, we examine whether the side effects of morphine treatment are also augmented in this animal model. Surprisingly, the genetic disruption of opioid receptor regulation, while enhancing and prolonging analgesia, dramatically attenuates the respiratory suppression and acute constipation caused by morphine.
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Affiliation(s)
- Kirsten M Raehal
- Department of Pharmacology and Psychiatry, Ohio State University College of Medicine, Columbus, 43210-1239, USA
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Métayé T, Gibelin H, Perdrisot R, Kraimps JL. Pathophysiological roles of G-protein-coupled receptor kinases. Cell Signal 2005; 17:917-28. [PMID: 15894165 DOI: 10.1016/j.cellsig.2005.01.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 01/11/2005] [Indexed: 12/19/2022]
Abstract
G-protein-coupled receptor kinases (GRKs) interact with the agonist-activated form of G-protein-coupled receptors (GPCRs) to effect receptor phosphorylation and to initiate profound impairment of receptor signalling, or desensitization. GPCRs form the largest family of cell surface receptors known and defects in GRK function have the potential consequence to affect GPCR-stimulated biological responses in many pathological situations. This review focuses on the physiological role of GRKs revealed by genetically modified animals but also develops the involvement of GRKs in human diseases as, Oguchi disease, heart failure, hypertension or rhumatoid arthritis. Furthermore, the regulation of GRK levels in opiate addiction, cancers, psychiatric diseases, cystic fibrosis and cardiac diseases is discussed. Both transgenic mice and human pathologies have demonstrated the importance of GRKs in the signalling pathways of rhodopsin, beta-adrenergic and dopamine-1 receptors. The modulation of GRK activity in animal models of cardiac diseases can be effective to restore cardiac function in heart failure and opens a novel therapeutic strategy in diseases with GPCR dysregulation.
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Affiliation(s)
- Thierry Métayé
- Department of Nuclear Medicine and Biophysics, Groupe de Recherche en Endocrinologie Expérimentale et Clinique, CHU de Poitiers, France.
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Johnson LR, Scott MGH, Pitcher JA. G protein-coupled receptor kinase 5 contains a DNA-binding nuclear localization sequence. Mol Cell Biol 2005; 24:10169-79. [PMID: 15542828 PMCID: PMC529036 DOI: 10.1128/mcb.24.23.10169-10179.2004] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
G protein-coupled receptor kinases (GRKs) mediate desensitization of agonist-occupied G protein-coupled receptors (GPCRs). Here we report that GRK5 contains a DNA-binding nuclear localization sequence (NLS) and that its nuclear localization is regulated by GPCR activation, results that suggest potential nuclear functions for GRK5. As assessed by fluorescence confocal microscopy, transfected and endogenous GRK5 is present in the nuclei of HEp2 cells. Mutation of basic residues in the catalytic domain of GRK5 (between amino acids 388 and 395) results in the nuclear exclusion of the mutant enzyme (GRK5(Delta)(NLS)), demonstrating that GRK5 contains a functional NLS. The nuclear localization of GRK5 is subject to dynamic regulation. Calcium ionophore treatment or activation of Gq-coupled muscarinic-M3 receptors promotes the nuclear export of the kinase in a Ca(2+)/calmodulin (Ca(2+)/CaM)-dependent fashion. Ca(2+)/CaM binding to the N-terminal CaM binding site of GRK5 mediates this effect. Furthermore, GRK5, but not GRK5(Delta)(NLS) or GRK2, binds specifically and directly to DNA in vitro. Consistent with their presence in the nuclei of transfected cells, all the GRK4, but not GRK2, subfamily members contain putative NLSs. These results suggest that the GRK4 subfamily of GRKs may play a signaling role in the nucleus and that GRK4 and GRK2 subfamily members perform divergent cellular functions.
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Affiliation(s)
- Laura R Johnson
- Laboratory for Molecular and Cellular Biology and Department of Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
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Gainetdinov RR, Premont RT, Bohn LM, Lefkowitz RJ, Caron MG. Desensitization of G protein-coupled receptors and neuronal functions. Annu Rev Neurosci 2004; 27:107-44. [PMID: 15217328 DOI: 10.1146/annurev.neuro.27.070203.144206] [Citation(s) in RCA: 624] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) have proven to be the most highly favorable class of drug targets in modern pharmacology. Over 90% of nonsensory GPCRs are expressed in the brain, where they play important roles in numerous neuronal functions. GPCRs can be desensitized following activation by agonists by becoming phosphorylated by members of the family of G protein-coupled receptor kinases (GRKs). Phosphorylated receptors are then bound by arrestins, which prevent further stimulation of G proteins and downstream signaling pathways. Discussed in this review are recent progress in understanding basics of GPCR desensitization, novel functional roles, patterns of brain expression, and receptor specificity of GRKs and beta arrestins in major brain functions. In particular, screening of genetically modified mice lacking individual GRKs or beta arrestins for alterations in behavioral and biochemical responses to cocaine and morphine has revealed a functional specificity in dopamine and mu-opioid receptor regulation of locomotion and analgesia. An important and specific role of GRKs and beta arrestins in regulating physiological responsiveness to psychostimulants and morphine suggests potential involvement of these molecules in certain brain disorders, such as addiction, Parkinson's disease, mood disorders, and schizophrenia. Furthermore, the utility of a pharmacological strategy aimed at targeting this GPCR desensitization machinery to regulate brain functions can be envisaged.
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Affiliation(s)
- Raul R Gainetdinov
- Howard Hughes Medical Institute Laboratories, Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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