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Dadam FM, Amigone JL, Vivas L, Macchione. Comparison of dipsogenic responses of adult rat offspring as a function of different perinatal programming models. Brain Res Bull 2022; 188:77-91. [PMID: 35882279 DOI: 10.1016/j.brainresbull.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 07/12/2022] [Accepted: 07/20/2022] [Indexed: 11/30/2022]
Abstract
The perinatal environment interacts with the genotype of the developing organism resulting in a unique phenotype through a developmental or perinatal programming phenomenon. However, it remains unclear how this phenomenon differentially affects particular targets expressing specific drinking responses depending on the perinatal conditions. The main goal of the present study was to compare the dipsogenic responses induced by different thirst models as a function of two perinatal manipulation models, defined by the maternal free access to hypertonic sodium solution and a partial aortic ligation (PAL-W/Na) or a sham-ligation (Sham-W/Na). The programmed adult offspring of both perinatal manipulated models responded similarly when was challenged by overnight water dehydration or after a sodium depletion showing a reduced water intake in comparison to the non-programmed animals. However, when animals were evaluated after a body sodium overload, only adult Sham-W/Na offspring showed drinking differences compared to PAL and control offspring. By analyzing the central neurobiological substrates involved, a significant increase in the number of Fos + cells was found after sodium depletion in the subfornical organ of both programmed groups and an increase in the number of Fos + cells in the dorsal raphe nucleus was only observed in adult depleted PAL-W/Na. Our results suggest that perinatal programming is a phenomenon that differentially affects particular targets which induce specific dipsogenic responses depending on matching between perinatal programming conditions and the osmotic challenge in the latter environment. Probably, each programmed-drinking phenotype has a particular set point to elicit specific repertoires of mechanisms to reestablish fluid balance.
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Affiliation(s)
- F M Dadam
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - J L Amigone
- Sección de Bioquímica Clínica, Hospital Privado, Córdoba, Argentina
| | - L Vivas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina; Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Macchione
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina.
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Beta-Arrestins in the Treatment of Heart Failure Related to Hypertension: A Comprehensive Review. Pharmaceutics 2021. [DOI: 10.3390/pharmaceutics13060838
expr 929824082 + 956151497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Abstract
Heart failure (HF) is a complicated clinical syndrome that is considered an increasingly frequent reason for hospitalization, characterized by a complex therapeutic regimen, reduced quality of life, and high morbidity. Long-standing hypertension ultimately paves the way for HF. Recently, there have been improvements in the treatment of hypertension and overall management not limited to only conventional medications, but several novel pathways and their pharmacological alteration are also conducive to the treatment of hypertension. Beta-arrestin (β-arrestin), a protein responsible for beta-adrenergic receptors’ (β-AR) functioning and trafficking, has recently been discovered as a potential regulator in hypertension. β-arrestin isoforms, namely β-arrestin1 and β-arrestin2, mainly regulate cardiac function. However, there have been some controversies regarding the function of the two β-arrestins in hypertension regarding HF. In the present review, we try to figure out the paradox between the roles of two isoforms of β-arrestin in the treatment of HF.
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3
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Rakib A, Eva TA, Sami SA, Mitra S, Nafiz IH, Das A, Tareq AM, Nainu F, Dhama K, Emran TB, Simal-Gandara J. Beta-Arrestins in the Treatment of Heart Failure Related to Hypertension: A Comprehensive Review. Pharmaceutics 2021; 13:838. [PMID: 34198801 PMCID: PMC8228839 DOI: 10.3390/pharmaceutics13060838] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/28/2021] [Accepted: 05/31/2021] [Indexed: 12/24/2022] Open
Abstract
Heart failure (HF) is a complicated clinical syndrome that is considered an increasingly frequent reason for hospitalization, characterized by a complex therapeutic regimen, reduced quality of life, and high morbidity. Long-standing hypertension ultimately paves the way for HF. Recently, there have been improvements in the treatment of hypertension and overall management not limited to only conventional medications, but several novel pathways and their pharmacological alteration are also conducive to the treatment of hypertension. Beta-arrestin (β-arrestin), a protein responsible for beta-adrenergic receptors' (β-AR) functioning and trafficking, has recently been discovered as a potential regulator in hypertension. β-arrestin isoforms, namely β-arrestin1 and β-arrestin2, mainly regulate cardiac function. However, there have been some controversies regarding the function of the two β-arrestins in hypertension regarding HF. In the present review, we try to figure out the paradox between the roles of two isoforms of β-arrestin in the treatment of HF.
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Affiliation(s)
- Ahmed Rakib
- Department of Pharmacy, Faculty of Biological Sciences, University of Chittagong, Chittagong 4331, Bangladesh; (A.R.); (T.A.E.); (S.A.S.)
| | - Taslima Akter Eva
- Department of Pharmacy, Faculty of Biological Sciences, University of Chittagong, Chittagong 4331, Bangladesh; (A.R.); (T.A.E.); (S.A.S.)
| | - Saad Ahmed Sami
- Department of Pharmacy, Faculty of Biological Sciences, University of Chittagong, Chittagong 4331, Bangladesh; (A.R.); (T.A.E.); (S.A.S.)
| | - Saikat Mitra
- Department of Pharmacy, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh;
| | - Iqbal Hossain Nafiz
- Department of Biochemistry and Molecular Biology, Faculty of Biological Sciences, University of Chittagong, Chittagong 4331, Bangladesh; (I.H.N.); (A.D.)
| | - Ayan Das
- Department of Biochemistry and Molecular Biology, Faculty of Biological Sciences, University of Chittagong, Chittagong 4331, Bangladesh; (I.H.N.); (A.D.)
| | - Abu Montakim Tareq
- Department of Pharmacy, International Islamic University Chittagong, Chittagong 4318, Bangladesh;
| | - Firzan Nainu
- Faculty of Pharmacy, Hasanuddin University, Tamalanrea, Kota Makassar, Sulawesi Selatan 90245, Indonesia;
| | - Kuldeep Dhama
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly 243122, Uttar Pradesh, India;
| | - Talha Bin Emran
- Department of Pharmacy, BGC Trust University Bangladesh, Chittagong 4381, Bangladesh
| | - Jesus Simal-Gandara
- Nutrition and Bromatology Group, Department of Analytical and Food Chemistry, Faculty of Food Science and Technology, University of Vigo–Ourense Campus, E32004 Ourense, Spain
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Lymperopoulos A, Wertz SL, Pollard CM, Desimine VL, Maning J, McCrink KA. Not all arrestins are created equal: Therapeutic implications of the functional diversity of the β-arrestins in the heart. World J Cardiol 2019; 11:47-56. [PMID: 30820275 PMCID: PMC6391623 DOI: 10.4330/wjc.v11.i2.47] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/28/2018] [Accepted: 01/10/2019] [Indexed: 02/06/2023] Open
Abstract
The two ubiquitous, outside the retina, G protein-coupled receptor (GPCR) adapter proteins, β-arrestin-1 and -2 (also known as arrestin-2 and -3, respectively), have three major functions in cells: GPCR desensitization, i.e., receptor decoupling from G-proteins; GPCR internalization via clathrin-coated pits; and signal transduction independently of or in parallel to G-proteins. Both β-arrestins are expressed in the heart and regulate a large number of cardiac GPCRs. The latter constitute the single most commonly targeted receptor class by Food and Drug Administration-approved cardiovascular drugs, with about one-third of all currently used in the clinic medications affecting GPCR function. Since β-arrestin-1 and -2 play important roles in signaling and function of several GPCRs, in particular of adrenergic receptors and angiotensin II type 1 receptors, in cardiac myocytes, they have been a major focus of cardiac biology research in recent years. Perhaps the most significant realization coming out of their studies is that these two GPCR adapter proteins, initially thought of as functionally interchangeable, actually exert diametrically opposite effects in the mammalian myocardium. Specifically, the most abundant of the two β-arrestin-1 exerts overall detrimental effects on the heart, such as negative inotropy and promotion of adverse remodeling post-myocardial infarction (MI). In contrast, β-arrestin-2 is overall beneficial for the myocardium, as it has anti-apoptotic and anti-inflammatory effects that result in attenuation of post-MI adverse remodeling, while promoting cardiac contractile function. Thus, design of novel cardiac GPCR ligands that preferentially activate β-arrestin-2 over β-arrestin-1 has the potential of generating novel cardiovascular therapeutics for heart failure and other heart diseases.
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Affiliation(s)
- Anastasios Lymperopoulos
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Shelby L Wertz
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Celina M Pollard
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Victoria L Desimine
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
| | - Jennifer Maning
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
- Jackson Memorial Hospital, Miami, FL 33136, United States
| | - Katie A McCrink
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences (Pharmacology), College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States
- Massachusetts General Hospital, Boston, MA 02114, United States
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Santollo J, Volcko KL, Daniels D. Sex Differences in the Behavioral Desensitization of Water Intake Observed After Repeated Central Injections of Angiotensin II. Endocrinology 2018; 159:676-684. [PMID: 29186291 PMCID: PMC5774252 DOI: 10.1210/en.2017-00848] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/21/2017] [Indexed: 01/13/2023]
Abstract
Previous in vivo and in vitro studies demonstrate that the angiotensin type 1 receptor rapidly desensitizes after exposure to angiotensin II (AngII). Behaviorally, this likely underlies the reduced drinking observed after acute repeated central injections of AngII. To date, this phenomenon has been studied exclusively in male subjects. Because there are sex differences in the dipsogenic potency of AngII, we hypothesized that sex differences also exist in desensitization caused by AngII. As expected, when male rats were pretreated with AngII, they drank less water after a test injection of AngII than did rats pretreated with vehicle. Intact cycling female rats, however, drank similar amounts of water after AngII regardless of the pretreatment. To probe the mechanism underlying this sex difference, we tested the role of gonadal hormones in adult and developing rats. Gonadectomy in adults did not produce a male-like propensity for desensitization of water intake in female rats, nor did it produce a female-like response in male rats. To test if neonatal brain masculinization generated a male-like responsiveness, female pups were treated at birth with vehicle, testosterone propionate (TP), or dihydrotestosterone (DHT). When tested as adults, TP-treated female rats showed a male-like desensitization after repeated AngII that was not found in vehicle- or DHT-treated rats. Together, these data reveal a striking sex difference in the behavioral response to elevated AngII that is mediated by organizational effects of gonadal hormones and provide an example of one of the many ways that sex influences the renin-angiotensin-aldosterone system.
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Affiliation(s)
- Jessica Santollo
- Department of Biology, University of Kentucky, Lexington, Kentucky 40506
| | - K. Linnea Volcko
- Department of Psychology, Behavioral Neuroscience Program, University at Buffalo, The State University of New York, Buffalo, New York 14260
| | - Derek Daniels
- Department of Psychology, Behavioral Neuroscience Program, University at Buffalo, The State University of New York, Buffalo, New York 14260
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Arrestins in the Cardiovascular System: An Update. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 159:27-57. [DOI: 10.1016/bs.pmbts.2018.07.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Morinelli TA, Luttrell LM, Strungs EG, Ullian ME. Angiotensin II receptors and peritoneal dialysis-induced peritoneal fibrosis. Int J Biochem Cell Biol 2016; 77:240-50. [PMID: 27167177 PMCID: PMC5038354 DOI: 10.1016/j.biocel.2016.04.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 12/22/2022]
Abstract
The vasoactive hormone angiotensin II initiates its major hemodynamic effects through interaction with AT1 receptors, a member of the class of G protein-coupled receptors. Acting through its AT1R, angiotensin II regulates blood pressure and renal salt and water balance. Recent evidence points to additional pathological influences of activation of AT1R, in particular inflammation, fibrosis and atherosclerosis. The transcription factor nuclear factor κB, a key mediator in inflammation and atherosclerosis, can be activated by angiotensin II through a mechanism that may involve arrestin-dependent AT1 receptor internalization. Peritoneal dialysis is a therapeutic modality for treating patients with end-stage kidney disease. The effectiveness of peritoneal dialysis at removing waste from the circulation is compromised over time as a consequence of peritoneal dialysis-induced peritoneal fibrosis. The non-physiological dialysis solution used in peritoneal dialysis, i.e. highly concentrated, hyperosmotic glucose, acidic pH as well as large volumes infused into the peritoneal cavity, contributes to the development of fibrosis. Numerous trials have been conducted altering certain components of the peritoneal dialysis fluid in hopes of preventing or delaying the fibrotic response with limited success. We hypothesize that structural activation of AT1R by hyperosmotic peritoneal dialysis fluid activates the internalization process and subsequent signaling through the transcription factor nuclear factor κB, resulting in the generation of pro-fibrotic/pro-inflammatory mediators producing peritoneal fibrosis.
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Affiliation(s)
- Thomas A Morinelli
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
| | - Louis M Luttrell
- Division of Endocrinology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States; Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401, United States
| | - Erik G Strungs
- Division of Endocrinology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States
| | - Michael E Ullian
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States; Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401, United States
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8
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Santollo J, Whalen PE, Speth RC, Clark SD, Daniels D. Properly timed exposure to central ANG II prevents behavioral sensitization and changes in angiotensin receptor expression. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1396-404. [PMID: 25354729 DOI: 10.1152/ajpregu.00373.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Previous studies show that the angiotensin type 1 receptor (AT1R) is susceptible to rapid desensitization, but that more chronic treatments that stimulate ANG II lead to sensitization of several responses. It is unclear, however, if the processes of desensitization and sensitization interact. To test for differences in AT1R expression associated with single or repeated injections of ANG II, we measured AT1R mRNA in nuclei that control fluid intake of rats given ANG II either in a single injection or divided into three injections spaced 20 min apart. Rats given a single injection of ANG II had more AT1R mRNA in the subfornical organ (SFO) and the periventricular tissue surrounding the anteroventral third ventricle (AV3V) than did controls. The effect was not observed, however, when the same cumulative dose of ANG II was divided into multiple injections. Behavioral tests found that single daily injections of ANG II sensitized the dipsogenic response to ANG II, but a daily regimen of four injections did not cause sensitization. Analysis of (125)I-Sar(1)-ANG II binding revealed a paradoxical decrease in binding in the caudal AV3V and dorsal median preoptic nucleus after 5 days of single daily injections of ANG II; however, this effect was absent in rats treated for 5 days with four daily ANG II injections. Taken together, these data suggest that a desensitizing treatment regimen prevents behavior- and receptor-level effects of repeated daily ANG II.
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Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo, State University of New York (SUNY), Buffalo, New York
| | - Philip E Whalen
- Department of Psychology, University at Buffalo, State University of New York (SUNY), Buffalo, New York
| | - Robert C Speth
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida; Department of Pharmacology and Physiology, College of Medicine, Georgetown University, Washington, DC; and
| | - Stewart D Clark
- Department of Pharmacology and Toxicology, University at Buffalo, SUNY, Buffalo, New York
| | - Derek Daniels
- Department of Psychology, University at Buffalo, State University of New York (SUNY), Buffalo, New York;
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βArrestins in cardiac G protein-coupled receptor signaling and function: partners in crime or "good cop, bad cop"? Int J Mol Sci 2013; 14:24726-41. [PMID: 24351844 PMCID: PMC3876138 DOI: 10.3390/ijms141224726] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 12/12/2013] [Accepted: 12/13/2013] [Indexed: 12/12/2022] Open
Abstract
βarrestin (βarr)-1 and -2 (βarrs) (or Arrestin-2 and -3, respectively) are universal G protein-coupled receptor (GPCR) adapter proteins expressed abundantly in extra-retinal tissues, including the myocardium. Both were discovered in the lab of the 2012 Nobel Prize in Chemistry co-laureate Robert Lefkowitz, initially as terminators of signaling from the β-adrenergic receptor (βAR), a process known as functional desensitization. They are now known to switch GPCR signaling from G protein-dependent to G protein-independent, which, in the case of βARs and angiotensin II type 1 receptor (AT1R), might be beneficial, e.g., anti-apoptotic, for the heart. However, the specific role(s) of each βarr isoform in cardiac GPCR signaling and function (or dysfunction in disease), remain unknown. The current consensus is that, whereas both βarr isoforms can desensitize and internalize cardiac GPCRs, they play quite different (even opposing in certain instances) roles in the G protein-independent signaling pathways they initiate in the cardiovascular system, including in the myocardium. The present review will discuss the current knowledge in the field of βarrs and their roles in GPCR signaling and function in the heart, focusing on the three most important, for cardiac physiology, GPCR types (β1AR, β2AR & AT1R), and will also highlight important questions that currently remain unanswered.
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10
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Daniels D. Diverse Roles of Angiotensin Receptor Intracellular Signaling Pathways in the Control of Water and Salt Intake. NEUROBIOLOGY OF BODY FLUID HOMEOSTASIS 2013. [DOI: 10.1201/b15544-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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11
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Arrestins in the cardiovascular system. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:297-334. [PMID: 23764059 DOI: 10.1016/b978-0-12-394440-5.00012-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Of the four mammalian arrestins, only the β-arrestins (βarrs; Arrestin2 and -3) are expressed throughout the cardiovascular system, where they regulate, as either desensitizers/internalizers or signal transducers, several G-protein-coupled receptors (GPCRs) critical for cardiovascular homeostasis. The cardiovascular roles of βarrs have been delineated at an accelerated pace via a variety of techniques and tools, such as knockout mice, siRNA knockdown, artificial or naturally occurring polymorphic GPCRs, and availability of new βarr "biased" GPCR ligands. This chapter summarizes the current knowledge of cardiovascular arrestin physiology and pharmacology, addressing the individual cardiovascular receptors affected by βarrs in vivo, as well as the individual cell types, tissues, and organs of the cardiovascular system in which βarr effects are exerted; for example, cardiac myocyte or fibroblast, vascular smooth muscle, adrenal gland and platelet. In the broader scope of cardiovascular βarr pharmacology, a discussion of the βarr "bias" of certain cardiovascular GPCR ligands is also included.
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12
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Vento PJ, Daniels D. Mitogen-activated protein kinase is required for the behavioural desensitization that occurs after repeated injections of angiotensin II. Exp Physiol 2012; 97:1305-14. [PMID: 22581747 DOI: 10.1113/expphysiol.2012.065771] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Angiotensin II (Ang II) acts on central angiotensin type 1 (AT(1)) receptors to increase water and saline intake. Prolonged exposure to Ang II in cell culture models results in a desensitization of the AT(1) receptor that is thought to involve receptor internalization, and a behavioural correlate of this desensitization has been shown in rats after repeated central injections of Ang II. Specifically, rats given repeated injections of Ang II drink less water than control animals after a subsequent test injection of Ang II. In the same conditions, however, repeated injections of Ang II have no effect on Ang II-induced saline intake. Given earlier studies indicating that separate intracellular signalling pathways mediate Ang II-induced water and saline intake, we hypothesized that the desensitization observed in rats may be incomplete, leaving the receptor able to activate mitogen-activated protein (MAP) kinases (ERK1/2), which play a role in Ang II-induced saline intake without affecting water intake. In support of this hypothesis, we found no difference in MAP kinase phosphorylation after an Ang II test injection in rats given prior treatment with repeated injections of vehicle, Ang II or Sar(1),Ile(4),Ile(8)-Ang II (SII), an Ang II analogue that activates MAP kinase without G protein coupling. In addition, we found that pretreatment with the MAP kinase inhibitor U0126 completely blocked the desensitizing effect of repeated Ang II injections on water intake. Furthermore, Ang II-induced water intake was reduced to a similar extent by repeated injections of Ang II or SII. The results suggest that G protein-independent signalling is sufficient to produce behavioural desensitization of the angiotensin system and that the desensitization requires MAP kinase activation.
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Affiliation(s)
- Peter J Vento
- Behavioral Neuroscience Program, Department of Psychology, The State University of New York at Buffalo, 14260, USA
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Kumar R, Yong QC, Thomas CM, Baker KM. Intracardiac intracellular angiotensin system in diabetes. Am J Physiol Regul Integr Comp Physiol 2011; 302:R510-7. [PMID: 22170614 DOI: 10.1152/ajpregu.00512.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The renin-angiotensin system (RAS) has mainly been categorized as a circulating and a local tissue RAS. A new component of the local system, known as the intracellular RAS, has recently been described. The intracellular RAS is defined as synthesis and action of ANG II intracellularly. This RAS appears to differ from the circulating and the local RAS, in terms of components and the mechanism of action. These differences may alter treatment strategies that target the RAS in several pathological conditions. Recent work from our laboratory has demonstrated significant upregulation of the cardiac, intracellular RAS in diabetes, which is associated with cardiac dysfunction. Here, we have reviewed evidence supporting an intracellular RAS in different cell types, ANG II's actions in cardiac cells, and its mechanism of action, focusing on the intracellular cardiac RAS in diabetes. We have discussed the significance of an intracellular RAS in cardiac pathophysiology and implications for potential therapies.
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Affiliation(s)
- Rajesh Kumar
- Division of Molecular Cardiology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, USA
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14
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Vento PJ, Myers KP, Daniels D. Investigation into the specificity of angiotensin II-induced behavioral desensitization. Physiol Behav 2011; 105:1076-81. [PMID: 22192708 DOI: 10.1016/j.physbeh.2011.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 12/05/2011] [Accepted: 12/06/2011] [Indexed: 11/16/2022]
Abstract
Angiotensin II (AngII) plays a key role in maintaining body fluid homeostasis. The physiological and behavioral effects of central AngII include increased blood pressure and fluid intake. In vitro experiments demonstrate that repeated exposure to AngII reduces the efficacy of subsequent AngII, and behavioral studies indicate that prior icv AngII administration reduces the dipsogenic response to AngII administered later. Specifically, rats given a treatment regimen of three icv injections of a large dose of AngII, each separated by 20 min, drink less water in response to a test injection of AngII than do vehicle-treated controls given the same test injection. The present studies were designed to test three potential explanations for the reduced dipsogenic potency of AngII after repeated administration. To this end, we tested for motor impairment caused by repeated injections of AngII, for a possible role of visceral distress or illness, and for differences in the pressor response to the final test injection of AngII. We found that repeated injections of AngII neither affected drinking stimulated by carbachol nor did they produce a conditioned flavor avoidance. Furthermore, we found no evidence that differences in the pressor response to the final test injection of AngII accounted for the difference in intake. In light of these findings, we are able to reject these three explanations for the observed behavioral desensitization, and, we suggest instead that the mechanism for this phenomenon may be at the level of the receptor.
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Affiliation(s)
- Peter J Vento
- Behavioral Neuroscience Program, Department of Psychology, The State University of New York at Buffalo, Buffalo, NY 14260, USA
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15
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Zapparoli A, Figueiredo JF, Boer PA, Rocha Gontijo JA. Impaired dipsogenic and renal response to repetitive intracerebroventricular angiotensin II (AngII) injections in rats. J Renin Angiotensin Aldosterone Syst 2011; 12:161-8. [PMID: 21393358 DOI: 10.1177/1470320310392617] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The role of the central nervous system (CNS) in the control of blood pressure and hydrosaline homeostasis has been demonstrated by several studies. While circulating angiotensin II (AngII) tends to retain sodium by a direct renal action as well as through aldosterone release, stimulation of brain AngII receptors has been reported to induce natriuresis. Repetitive intracerebroventricular AngII injection was recently demonstrated to be capable of leading to desensitisation of the dipsogenic effect of AngII stimuli. The aim of the current study was to investigate a possible central desensitisation to AngII stimuli by observing the effects of a low-concentration solution of AngII on the dipsogenic and natriuretic mechanisms in conscious rats, compared with appropriate age-matched 0.15 M NaCl-injected subjects, as evaluated by lithium clearance. The present report confirmed earlier reports on the potent natriuretic and dipsogenic effects of central AngII receptor stimulation. Natriuresis is mediated by a decrease in sodium reabsorption in the proximal and post-proximal tubule segments of the nephron. The current findings lend further support to the idea that AngII, in the CNS, is instrumental in the regulation of body fluid homeostasis. The magnitude of the dipsogenic and renal response to AngII was significantly decreased by repetitive stimulus.
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Affiliation(s)
- Adriana Zapparoli
- Disciplina de Medicina Interna, Laboratório de Metabolismo Hidro-Salino, Núcleo de Medicina e Cirurgia Experimental, Departamento de Clínica Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Sao Paolo, Brazil
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16
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Daniels D. Alan [corrected] N. Epstein award: Intracellular signaling and ingestive behaviors. Physiol Behav 2010; 100:496-502. [PMID: 20346964 DOI: 10.1016/j.physbeh.2010.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 03/08/2010] [Accepted: 03/12/2010] [Indexed: 12/12/2022]
Abstract
Understanding the role of intracellular signaling pathways in ingestive behavior is a challenging problem in behavioral neuroscience. This review summarizes work conducted on two systems with the aim of identifying intracellular events that relate to food and fluid intake. The first set of experiments focused on melanocortin receptors and their ability to signal through members of the mitogen-activated protein (MAP) kinase family. The second set of experiments focused on the role of intracellular signaling pathways in water and saline intakes that are stimulated by angiotensin II (AngII). The initial findings in each line of research have been extended by subsequent research that is discussed in turn. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.
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Affiliation(s)
- Derek Daniels
- Behavioral Neuroscience Program, Department of Psychology, The State University of New York at Buffalo, SUNY, Buffalo, New York 14260, USA.
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Vento PJ, Daniels D. Repeated administration of angiotensin II reduces its dipsogenic effect without affecting saline intake. Exp Physiol 2010; 95:736-45. [PMID: 20228119 DOI: 10.1113/expphysiol.2010.052191] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Angiotensin II (Ang II) acts at central type 1 (AT(1)) receptors to increase intake of water and saline. In vitro studies demonstrated rapid desensitization of the AT(1) receptor after Ang II exposure, and behavioural studies in rats suggest that exposure to Ang II decreases the dipsogenic potency of subsequent Ang II. Nevertheless, the effect of repeated Ang II injections on saline intake remains untested, and a reliable protocol for examining this purported behavioural desensitization has not emerged from the literature. To address these issues, we established a reliable approach to study Ang II-induced dipsetic desensitization and used this approach to test the requirement of central AT(1) receptors and the specificity of the effect for water intake. Rats given a treatment regimen of three injections of Ang II (300 ng, intracerebroventricular), each separated by 20 min, drank less water than control rats after a subsequent test injection of Ang II. The effect was relatively short lasting, dependent on the dose and timing of Ang II, and was almost completely blocked by the AT(1) receptor antagonist losartan. In further testing, when rats were given access to both water and 1.5% saline, animals that received an Ang II treatment regimen drank less water than control animals, but saline intake was unaffected. These data support previous suggestions that Ang II-induced water and saline intakes are separable. Given the role of G protein uncoupling in desensitization of the AT(1) receptor, these data are consistent with the emerging hypothesis that AT(1) receptor G protein-dependent intracellular signalling pathways are more relevant for water, but not saline, intake.
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Affiliation(s)
- Peter J Vento
- Department of Psychology, University at Buffalo, SUNY, Buffalo, NY 14260, USA
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18
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Baker KM, Kumar R. Intracellular angiotensin II induces cell proliferation independent of AT1 receptor. Am J Physiol Cell Physiol 2006; 291:C995-1001. [PMID: 16774988 DOI: 10.1152/ajpcell.00238.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We recently reported intracrine effects of angiotensin II (ANG II) on cardiac myocyte growth and hypertrophy that were not inhibited by the ANG II type 1 receptor (AT1) antagonist, losartan. To further determine the role of AT1 in intracrine effects, we studied the effect of intracellular ANG II (iANG II) on cell proliferation in native Chinese hamster ovary (CHO) cells and those stably transfected with AT1 receptor (CHO-AT1). CHO-AT1, but not CHO cells, showed enhanced proliferation following exposure to extracellular ANG II (eANG II). However, when transiently transfected with an iANG II expression vector, both cell types showed significantly enhanced proliferation, compared with those transfected with a scrambled peptide. Losartan blocked eANG II-induced cell proliferation, but not that induced by iANG II. To further confirm these findings, CHO and CHO-AT1 cells were stably transfected for iANG II expression (CHO-iA and CHO-AT1-iA, respectively). Cells grown in serum-free medium were counted every 24 h, up to 72 h. CHO-iA and CHO-AT1-iA cells showed a steeper growth curve compared with CHO and CHO-AT1, respectively. These observations were confirmed by Wst-1 assay. The AT1 receptor antagonists losartan, valsartan, telmisartan, and candesartan did not attenuate the faster growth rate of CHO-iA and CHO-AT1-iA cells. eANG II showed an additional growth effect in CHO-AT1-iA cells, which could be selectively blocked by losartan. These data demonstrate that intracrine ANG II can act independent of AT1 receptors and suggest novel intracellular mechanisms of action for ANG II.
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Affiliation(s)
- Kenneth M Baker
- Cardiovascular Research Institute, The Texas A&M University System Health Science Center, Temple, TX 76504, USA
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19
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Yee DK, Suzuki A, Luo L, Fluharty SJ. Identification of Structural Determinants for G Protein-Independent Activation of Mitogen-Activated Protein Kinases in the Seventh Transmembrane Domain of the Angiotensin II Type 1 Receptor. Mol Endocrinol 2006; 20:1924-34. [PMID: 16556732 DOI: 10.1210/me.2006-0018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Although the intrareceptor mechanisms whereby the angiotensin II (AngII) type 1 receptor activates phospholipase C (PLC) have been extensively investigated, analogous studies of signaling through mitogen-activated protein kinases (MAPK) have been lacking. We investigated MAPK activation and traditional G(q)/PLC signaling in transfected cells using AngII and the signaling selective agonist [Sar(1),Ile(4),Ile(8)] AngII (SII). SII stimulated MAPK without inositol trisphosphate (IP(3)) production and thereby stabilizes an activated receptor state linked to G protein-independent MAPK signaling. Using receptor mutagenesis, we focused on the seventh transmembrane domain and identified three key residues-Tyr(292), Phe(293), and Thr(287). At least three distinct activated states were revealed: 1) an AngII-stabilized state linked to G(q)/PLC signaling, 2) an AngII-stabilized state connected to G protein-independent MAPK activation, and 3) a SII-stabilized state associated with G protein-independent MAPK signaling. The mutant Y292F failed to exhibit AngII-induced IP(3) turnover yet remained capable of AngII-induced MAPK activation. SII failed to stimulate MAPK in Y292F-transfected cells. Thus, Tyr(292) is a key epitope for activated states 1 and 3 but not required for activated state 2. Although the F293L mutant retained normal AngII responses, it also showed an IP(3) response to SII, indicating that Phe(293) may be involved in constraining the receptor to its inactive state. Mutations of Thr(287) abolished all SII-induced signaling without affecting any AngII responses. Thr(287) therefore represents a key residue for a SII-stabilized activated state. Taken together, the data identified a novel structural requirement (Thr(287)) for the SII-stabilized activated state and redefined the mechanistic roles for Tyr(292) and Phe(293).
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MESH Headings
- Animals
- COS Cells
- Chlorocebus aethiops
- Conserved Sequence
- Enzyme Activation/physiology
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Extracellular Signal-Regulated MAP Kinases/physiology
- GTP-Binding Proteins/metabolism
- GTP-Binding Proteins/physiology
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Models, Biological
- Mutation
- Point Mutation
- Protein Structure, Quaternary
- Protein Structure, Tertiary
- Rats
- Receptor, Angiotensin, Type 1/agonists
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Transfection
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Affiliation(s)
- Daniel K Yee
- Department of Animal Biology, University of Pennsylvania, Philadelphia, 19104-6046, USA.
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20
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Alvarez BV, Vilas GL, Casey JR. Metabolon disruption: a mechanism that regulates bicarbonate transport. EMBO J 2005; 24:2499-511. [PMID: 15990874 PMCID: PMC1176462 DOI: 10.1038/sj.emboj.7600736] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Accepted: 06/08/2005] [Indexed: 02/07/2023] Open
Abstract
Carbonic anhydrases (CA) catalyze the reversible conversion of CO2 to HCO3-. Some bicarbonate transporters bind CA, forming a complex called a transport metabolon, to maximize the coupled catalytic/transport flux. SLC26A6, a plasma membrane Cl-/HCO3- exchanger with a suggested role in pancreatic HCO3- secretion, was found to bind the cytoplasmic enzyme CAII. Mutation of the identified CAII binding (CAB) site greatly reduced SLC26A6 activity, demonstrating the importance of the interaction. Regulation of SLC26A6 bicarbonate transport by protein kinase C (PKC) was investigated. Angiotensin II (AngII), which activates PKC, decreased Cl-/HCO3- exchange in cells coexpressing SLC26A6 and AT1a-AngII receptor. Activation of PKC reduced SLC26A6/CAII association in immunoprecipitates. Similarly, PKC activation displaced CAII from the plasma membrane, as monitored by immunofluorescence. Finally, mutation of a PKC site adjacent to the SLC26A6 CAB site rendered the transporter unresponsive to PKC. PKC therefore reduces CAII/SLC26A6 interaction, reducing bicarbonate transport rate. Taken together, our data support a mechanism for acute regulation of membrane transport: metabolon disruption.
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Affiliation(s)
- Bernardo V Alvarez
- Membrane Protein Research Group, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Gonzalo L Vilas
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph R Casey
- Membrane Protein Research Group, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7. Tel.: +1 780 492 7203; Fax: +1 780 492 8915; E-mail:
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21
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Baker KM, Chernin MI, Schreiber T, Sanghi S, Haiderzaidi S, Booz GW, Dostal DE, Kumar R. Evidence of a novel intracrine mechanism in angiotensin II-induced cardiac hypertrophy. ACTA ACUST UNITED AC 2005; 120:5-13. [PMID: 15177915 DOI: 10.1016/j.regpep.2004.04.004] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Revised: 04/07/2004] [Accepted: 04/07/2004] [Indexed: 11/29/2022]
Abstract
Angiotensin II (Ang II) has a significant role in regulating cardiac homeostasis through humoral, autocrine and paracrine pathways, via binding to the plasma membrane AT1 receptor. Recent literature has provided evidence for intracrine growth effects of Ang II in some cell lines, which does not involve interaction with the plasma membrane receptor. We hypothesized that such intracrine mechanisms are operative in the heart and likely participate in the cardiac hypertrophy induced by Ang II. Adenoviral and plasmid vectors were constructed to express Ang II peptide intracellularly. Neonatal rat ventricular myocytes (NRVMs) infected with the adenoviral vector showed significant hypertrophic growth as determined by cell size, protein synthesis and enhanced cytoskeletal arrangement. Adult mice injected with the plasmid vector developed significant cardiac hypertrophy after 48 h, without an increase in blood pressure or plasma Ang II levels. This was accompanied by increased transcription of transforming growth factor-beta (TGF-beta) and insulin-like growth factor-1 (IGF-1) genes. Losartan did not block the growth effects, excluding the involvement of extracellular Ang II and the plasma membrane AT1 receptor. These data demonstrate a previously unknown growth mechanism of Ang II in the heart, which should be considered when designing therapeutic strategies to block Ang II actions.
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Affiliation(s)
- Kenneth M Baker
- Division of Molecular Cardiology, Cardiovascular Research Institute, The Texas A&M University System Health Science Center, College of Medicine, 1901 S 1st Street, Building 205, Temple 76504, USA
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22
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Calegari VC, Bezerra RMN, Torsoni MA, Torsoni AS, Franchini KG, Saad MJA, Velloso LA. Suppressor of cytokine signaling 3 is induced by angiotensin II in heart and isolated cardiomyocytes, and participates in desensitization. Endocrinology 2003; 144:4586-96. [PMID: 12960061 DOI: 10.1210/en.2003-0046] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II (Ang II) exerts a potent growth stimulus on the heart and vascular wall. Activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) intracellular signaling pathway by Ang II mediates at least some of the mitogenic responses to this hormone. In other signaling systems that use the JAK/STAT pathway, proteins of the suppressor of cytokine signaling (SOCS) family participate in signal regulation. In the present study it is demonstrated that SOCS3 is constitutively expressed at a low level in rat heart and neonatal rat ventricular myocytes. Ang II at a physiological concentration enhances the expression of SOCS3 mRNA and protein, mainly via AT1 receptors. After induction, SOCS3 associates with JAK2 and impairs further activation of the JAK2/STAT1 pathway. Pretreatment of rats with a specific phosphorthioate antisense oligonucleotide to SOCS3, reverses the desensitization to angiotensin signaling, as detected by a fall in c-Jun expression after repetitive infusions of the hormone. Thus, SOCS3 is induced by Ang II in rat heart and neonatal rat ventricular myocytes and participates in the modulation of the signal generated by this hormone.
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Affiliation(s)
- Vivian C Calegari
- Department of Internal Medicine, State University of Campinas, 13084 970 Campinas SP, Brazil
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23
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Hines J, Fluharty SJ, Yee DK. Structural determinants for the activation mechanism of the angiotensin II type 1 receptor differ for phosphoinositide hydrolysis and mitogen-activated protein kinase pathways. Biochem Pharmacol 2003; 66:251-62. [PMID: 12826267 DOI: 10.1016/s0006-2952(03)00257-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
While the mechanism whereby the angiotensin II type 1 receptor (AT(1) receptor) activates its classical effector phospholipase C-beta (PLC-beta) has largely been elucidated, there is little consensus on how this receptor activates a more recently identified effector, the p42/44 mitogen-activated protein kinases (p42/44(MAPK)). Using transfected COS-1 cells, we investigated the activation of this signaling pathway at the receptor level itself. Previous mutational studies that relied on phosphoinositide turnover as an index of receptor activation have indicated that key residues in the second and seventh transmembrane domains participate in AT(1) receptor activation mechanisms. Thus, we introduced a variety of mutations-AT(1)[D74N], AT(1)[Y292F], AT(1)[N295S], and AT(1)[AT(2) TM7], which is composed of a chimeric substitution of the AT(1) seventh transmembrane domain with its AT(2) counterpart. These mutations that strongly diminished the receptor's ability to activate PLC-beta had little to no effect on its ability to activate p42/44(MAPK), which not only suggests that p42/44(MAPK) does not exclusively lie downstream of the G-protein G(q)/PLC-beta pathway but also indicates that more than one activation state may exist for the AT(1) receptor. The failure of a protein kinase C inhibitor to block AT(1) receptor activation of p42/44(MAPK) further corroborated evidence that the receptor's activation of p42/44(MAPK) is largely independent of the G(q)/PLC-beta/PKC pathway. Taken together, the experimental evidence strongly suggests that the mechanism whereby the AT(1) receptor activates p42/44(MAPK) is fundamentally different from that for PLC-beta, even at the level of the receptor itself.
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Affiliation(s)
- John Hines
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104-6046, USA
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24
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Fabiani ME, Hawkes DJ, Frauman AG, Tikellis C, Johnston CI, Wilkinson-Berka JL. Regulation of angiotensin II receptors in the prostate of the transgenic (mRen-2)27 rat: effect of angiotensin-converting enzyme inhibition. Int J Biochem Cell Biol 2003; 35:973-83. [PMID: 12676181 DOI: 10.1016/s1357-2725(02)00303-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We examined the regulation/expression of angiotensin II (Ang II) receptors in the transgenic (TG) (mRen-2)27 rat compared to the normal Sprague-Dawley (SD) rat. Ang II receptor binding and mRNA expression were determined by quantitative autoradiography and real-time PCR, respectively. Ang II receptors in the rat prostate rat were of the AT(1) receptor subtype and were significantly reduced in the prostate of the TG rat compared to the normal SD rat. However, AT(1) receptor binding was significantly higher in the prostate of the TG rat treated with the ACE inhibitor lisinopril compared to the untreated TG rat and comparable to the control SD rat. In contrast to the protein, AT(1) receptor mRNA expression was not reduced in the prostate of the TG rat compared to the SD rat. However, AT(1) receptor mRNA was markedly reduced in the prostate of the lisinopril-treated TG rat compared to the untreated TG rat or control SD rat. In conclusion, the findings suggest that AT(1) receptors are present in the rat prostate at a protein level and are subject to down-regulation in the TG rat which may be due to receptor internalisation as a consequence of receptor hyper-stimulation by increased local tissue levels of Ang II. Moreover, AT(1) receptor protein and mRNA expression in the prostate may be inversely modulated.
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Affiliation(s)
- Maurice E Fabiani
- Department of Medicine, University of Melbourne, Austin and Repatriation Medical Centre, Heidelberg, VIC 3084, Australia.
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25
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Crowley CM, Lee CH, Gin SA, Keep AM, Cook RC, Van Breemen C. The mechanism of excitation-contraction coupling in phenylephrine-stimulated human saphenous vein. Am J Physiol Heart Circ Physiol 2002; 283:H1271-81. [PMID: 12234776 DOI: 10.1152/ajpheart.01129.2001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The human saphenous vein (HSV) is the most widely used graft in coronary artery revascularization procedures and is susceptible to spasm perioperatively. The aim of this study is to elucidate the mechanism(s) of agonist-induced excitation-contraction coupling in this vessel. Isometric contraction experiments were combined with in situ smooth muscle intracellular Ca(2+) concentration ([Ca(2+)](i)) imaging by confocal microscopy of intact undistended HSV segments during activation with phenylephrine (PE; 50 microM). Stimulation with PE produced a sustained contraction. Preincubation with 5 microM nifedipine, a blocker of the L-type voltage-operated Ca(2+) channel, or 50 microM SKF-96365, a blocker of both the voltage- and receptor-operated channels, reduced force generation by 25-30%. Ca(2+) imaging revealed that PE elicited only a transient rise in [Ca(2+)](i), suggesting that Ca(2+) plays only a minor role. However, a requirement for basal Ca(2+) levels was demonstrated when PE contractions could not be maintained in Ca(2+)-free medium. In light of the transient Ca(2+) response, it appears that signals other than Ca(2+) must maintain the tonic contraction elicited by PE, such as those that sensitize the myofilaments to Ca(2+). Application of HA-1077 (a Rho kinase inhibitor) at the peak of the contraction completely abolished the plateau phase of the response, whereas application of genistein (a tyrosine kinase inhibitor) reduced this phase by approximately 50%. The foregoing results suggest that, whereas the transient Ca(2+) signal can contribute to the development of force, maintenance of the plateau phase of the PE contraction in the HSV is the result of myofilament Ca(2+) sensitization by Rho kinase and tyrosine phosphorylation. The elucidation of the mechanisms of excitation-contraction coupling in the HSV may be useful for the development of therapeutic strategies for the alleviation of vein graft spasm.
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Affiliation(s)
- Christine M Crowley
- iCAPTURE Centre, Vancouver Vascular Biology Research Centre, St. Paul's Hospital, University of British Columbia, V5Z 4E3 Canada
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26
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Ishihata A, Tasaki K, Katano Y. Involvement of p44/42 mitogen-activated protein kinases in regulating angiotensin II- and endothelin-1-induced contraction of rat thoracic aorta. Eur J Pharmacol 2002; 445:247-56. [PMID: 12079690 DOI: 10.1016/s0014-2999(02)01790-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In order to elucidate the signal transduction pathway of vascular smooth muscle contraction induced by the activation of receptors for angiotensin II and endothelin-1, we examined whether tyrosine kinases and mitogen-activated protein (MAP) kinases are involved in the development of force of contraction in the rat aorta. Isolated aortic smooth muscles without endothelium were incubated in a modified Krebs-Henseleit solution and stimulated with angiotensin II (100 nM) or endothelin-1 (10 nM). A tyrosine kinase inhibitor genistein (10 microM) reduced the angiotensin II- and endothelin-1-induced aortic contraction, while 10 microM of daidzein (an inactive analogue of genistein) did not. The K(+) depolarization-induced contraction was not attenuated by 10 microM of genistein. Selective inhibitors of MAP kinase/extracellular signal-regulated kinase (Erk) kinase (MEK) such as PD98059 [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one] and U0126 [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene] inhibited the angiotensin II- and endothelin-1-induced vasocontraction. The p44/42 MAP kinases were phosphorylated in cultured aortic smooth muscle cells and in physiologically contracted aortic vessels stimulated with angiotensin II and endothelin-1 for 5 min. The angiotensin II- and endothelin-1-induced phosphorylations of p44/42 MAP kinases were inhibited by PD98059 as well as U0126 in the intact aorta. These results suggest that the activation of genistein-sensitive tyrosine kinases and p44/42 MAP kinases is involved in the angiotensin II- and endothelin-1-induced rat aortic contraction.
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Affiliation(s)
- Akira Ishihata
- Department of Physiology I, Yamagata University School of Medicine, 2-2-2, Iida-Nishi, Japan.
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27
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Holloway AC, Qian H, Pipolo L, Ziogas J, Miura SI, Karnik S, Southwell BR, Lew MJ, Thomas WG. Side-chain substitutions within angiotensin II reveal different requirements for signaling, internalization, and phosphorylation of type 1A angiotensin receptors. Mol Pharmacol 2002; 61:768-77. [PMID: 11901215 DOI: 10.1124/mol.61.4.768] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Binding of the peptide hormone angiotensin II (AngII) to the type 1 (AT(1A)) receptor and the subsequent activation of phospholipase C-mediated signaling, involves specific determinants within the AngII peptide sequence. In contrast, the contribution of such determinants to AT(1A) receptor internalization, phosphorylation and activation of mitogen-activated protein kinase (MAPK) signaling is not known. In this study, the internalization of an enhanced green fluorescent protein-tagged AT(1A) receptor (AT(1A)-EGFP), in response to AngII and a series of substituted analogs, was visualized and quantified using confocal microscopy. AngII-stimulation resulted in a rapid, concentration-dependent internalization of the chimeric receptor, which was prevented by pretreatment with the nonpeptide AT(1) receptor antagonist EXP3174. Remarkably, AT(1A) receptor internalization was unaffected by substitution of AngII side chains, including single and double substitutions of Tyr(4) and Phe(8) that abolish phospholipase C signaling through the receptor. AngII-induced receptor phosphorylation was significantly inhibited by several substitutions at Phe(8) as well as alanine replacement of Asp(1). The activation of MAPK was only significantly inhibited by substitutions at position eight in the peptide and specific substitutions did not equally inhibit inositol phosphate production, receptor phosphorylation and MAPK activation. These results indicate that separate, yet overlapping, contacts made between the AngII peptide and the AT(1A) receptor select/induce distinct receptor conformations that preferentially affect particular receptor outcomes. The requirements for AT(1A) receptor internalization seem to be less stringent than receptor activation and signaling, suggesting an inherent bias toward receptor deactivation.
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Affiliation(s)
- Alice C Holloway
- Molecular Endocrinology Laboratory, Baker Medical Research Institute, Melbourne, Australia
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28
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Abstract
-The active end product of the renin-angiotensin system, angiotensin II (Ang II), through the activation of specific Ang II receptors, regulates cardiac contractility, cell coupling, and impulse propagation and is involved in cardiac remodeling, growth, and apoptosis. We review these subjects, as well as the second messengers that are involved, and the synthesis of Ang II in the heart under normal and pathological conditions. Finally, we discuss the possibility that there is an intracrine renin-angiotensin system in the heart that plays a role in the control of cell communication and inward Ca(2+) current.
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Affiliation(s)
- W C De Mello
- Department of Pharmacology, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067
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29
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Booz GW, Carl LL, Baker KM. Amplification of angiotensin II signaling in cardiac myocytes by adenovirus-mediated overexpression of the AT1 receptor. Ann N Y Acad Sci 1999; 874:20-6. [PMID: 10415517 DOI: 10.1111/j.1749-6632.1999.tb09221.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Low levels of AT1 receptor can make studying the growth-related signal transduction events mediated by this angiotensin II receptor in cardiac myocytes technically difficult. The purpose of the present study was to establish whether an adenovirus expression system could be used to increase the number of plasma membrane AT1 receptors in neonatal rat ventricular myocytes, thereby amplifying the signaling pathways activated by this receptor. Cardiac myocytes infected with adenovirus expressing the AT1 receptor exhibited increased ligand binding. The overexpressed receptor appeared to function like the endogenous receptor, in regard to agonist-induced internalization, as well as coupling to MAPK activation and protein tyrosine phosphorylation events. In addition, adenovirus-mediated overexpression of the AT1 receptor resulted in the amplification of angiotensin II intracellular signaling. In conclusion, adenovirus-mediated overexpression of angiotensin II receptors appears to be a useful strategy for studying the signal transduction events activated by this hormone in cardiac myocytes and for unraveling the molecular means by which this receptor type couples to a hypertrophic pattern of growth and gene expression.
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Affiliation(s)
- G W Booz
- Henry Hood MD Research Program, Pennsylvania State University College of Medicine, Weis Center for Research, Danville 17822-2611, USA.
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30
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Abstract
The type 1 angiotensin receptor (AT1) mediates the important biological actions of the peptide hormone, angiotensin II (AngII), by activating an array of intracellular signaling pathways. The unique temporal arrangement and duration of AngII-stimulated signals suggests a hierarchy of post-AT1 receptor binding events that permits activation of selective effector pathways. Moreover, it predicts that the coupling of AT1 receptors is tightly regulated, allowing cells to differentiate acute responses from those requiring longer periods of stimulation. Recent studies have concentrated on delineating the molecular processes involved in modulating AT1 receptor activity. In addition to AT1 receptor modification (phosphorylation), trafficking (internalization and degradation) and interaction with regulatory intracellular proteins, other processes may include receptor dimerization, cross-regulation by other receptor systems, and receptor isomerization between activated and non-activated forms. This review focuses on recent advances in this area of research, highlighting directions for future investigation.
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Affiliation(s)
- W G Thomas
- Molecular Endocrinology Laboratory, Baker Medical Research Institute, Melbourne, Australia.
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31
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Mascareno E, Dhar M, Siddiqui MA. Signal transduction and activator of transcription (STAT) protein-dependent activation of angiotensinogen promoter: a cellular signal for hypertrophy in cardiac muscle. Proc Natl Acad Sci U S A 1998; 95:5590-4. [PMID: 9576927 PMCID: PMC20422 DOI: 10.1073/pnas.95.10.5590] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The role of the peptide hormone angiotensin (AngII) in promoting myocardial hypertrophy is well documented. Our studies demonstrate that AngII uses a signaling pathway in cardiac myocytes in which the promoter of the gene encoding its prohormone, angiotensinogen, serves as the target site for activated signal transduction and activator of transcription (STAT) proteins. Gel mobility-shift assay revealed that STAT3 and STAT6 are selectively activated by AngII treatment of cardiomyocytes in culture and bind to a sequence motif (St-domain) in the angiotensinogen promoter to activate its transcription in transient transfection assay. We have also observed a dramatic increase in the St-domain binding activity of STAT proteins in the hypertrophied heart of the genetically hypertensive rat relative to that of the aged-matched normotensive strain WKY, providing a compelling argument in favor of the linkage of STAT pathway to the heart tissue autocrine AngII loop. These studies thus uncover a mechanism by which the activation of a selective set of STATs underlies mobilization of the gene activation program intrinsic to cardiac hypertrophy.
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Affiliation(s)
- E Mascareno
- Center for Cardiovascular and Muscle Research and Department of Anatomy and Cell Biology, State University of New York Health Science Center at Brooklyn, Brooklyn, NY 11203, USA
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