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Tsilosani A, Gao C, Zhang W. Aldosterone-Regulated Sodium Transport and Blood Pressure. Front Physiol 2022; 13:770375. [PMID: 35197862 PMCID: PMC8859437 DOI: 10.3389/fphys.2022.770375] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
Aldosterone is a major mineralocorticoid steroid hormone secreted by glomerulosa cells in the adrenal cortex. It regulates a variety of physiological responses including those to oxidative stress, inflammation, fluid disruption, and abnormal blood pressure through its actions on various tissues including the kidney, heart, and the central nervous system. Aldosterone synthesis is primarily regulated by angiotensin II, K+ concentration, and adrenocorticotrophic hormone. Elevated serum aldosterone levels increase blood pressure largely by increasing Na+ re-absorption in the kidney through regulating transcription and activity of the epithelial sodium channel (ENaC). This review focuses on the signaling pathways involved in aldosterone synthesis and its effects on Na+ reabsorption through ENaC.
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Affiliation(s)
- Akaki Tsilosani
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Chao Gao
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Wenzheng Zhang
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
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2
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Chang M, Chen B, Shaffner J, Dworkin LD, Gong R. Melanocortin System in Kidney Homeostasis and Disease: Novel Therapeutic Opportunities. Front Physiol 2021; 12:651236. [PMID: 33716796 PMCID: PMC7943476 DOI: 10.3389/fphys.2021.651236] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/03/2021] [Indexed: 12/30/2022] Open
Abstract
Melanocortin peptides, melanocortin receptors, melanocortin receptor accessory proteins, and endogenous antagonists of melanocortin receptors are the key components constituting the melanocortin hormone system, one of the most complex and important hormonal systems in our body. A plethora of evidence suggests that melanocortins possess a protective activity in a variety of kidney diseases in both rodent models and human patients. In particular, the steroidogenic melanocortin peptide adrenocorticotropic hormone (ACTH), has been shown to exert a beneficial effect in a number of kidney diseases, possibly via a mechanism independent of its steroidogenic activity. In patients with steroid-resistant nephrotic glomerulopathy, ACTH monotherapy is still effective in inducing proteinuria remission. This has inspired research on potential implications of the melanocortin system in glomerular diseases. However, our understanding of the role of the melanocortinergic pathway in kidney disease is very limited, and there are still huge unknowns to be explored. The most controversial among these is the identification of effector cells in the kidney as well as the melanocortin receptors responsible for conveying the renoprotective action. This review article introduces the melanocortin hormone system, summarizes the existing evidence for the expression of melanocortin receptors in the kidney, and evaluates the potential strategy of melanocortin therapy for kidney disease.
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Affiliation(s)
- Mingyang Chang
- Division of Nephrology, Department of Medicine, University of Toledo College of Medicine, Toledo, OH, United States
| | - Bohan Chen
- Division of Nephrology, Department of Medicine, University of Toledo College of Medicine, Toledo, OH, United States
| | - James Shaffner
- Division of Nephrology, Department of Medicine, University of Toledo College of Medicine, Toledo, OH, United States
| | - Lance D Dworkin
- Division of Nephrology, Department of Medicine, University of Toledo College of Medicine, Toledo, OH, United States
| | - Rujun Gong
- Division of Nephrology, Department of Medicine, University of Toledo College of Medicine, Toledo, OH, United States
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3
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Tsai YY, Rainey WE, Johnson MH, Bollag WB. VLDL-activated cell signaling pathways that stimulate adrenal cell aldosterone production. Mol Cell Endocrinol 2016; 433:138-46. [PMID: 27222295 PMCID: PMC4955520 DOI: 10.1016/j.mce.2016.05.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/20/2016] [Accepted: 05/20/2016] [Indexed: 01/29/2023]
Abstract
Aldosterone plays an important role in regulating ion and fluid homeostasis and thus blood pressure, and hyperaldosteronism results in hypertension. Hypertension is also observed with obesity, which is associated with additional health risks, including cardiovascular disease. Obese individuals have high serum levels of very low-density lipoprotein (VLDL), which has been shown to stimulate aldosterone production; however, the mechanisms underlying VLDL-induced aldosterone production are still unclear. Here we demonstrate in human adrenocortical carcinoma (HAC15) cells that submaximal concentrations of angiotensin II and VLDL stimulate aldosterone production in an additive fashion, suggesting the possibility of common mechanisms of action. We show using inhibitors that VLDL-induced aldosterone production is mediated by the PLC/IP3/PKC signaling pathway. Our results suggest that PKC is upstream of the extracellular signal-regulated kinase (ERK) activation previously observed with VLDL. An understanding of the mechanisms mediating VLDL-induced aldosterone production may provide insights into therapies to treat obesity-associated hypertension.
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Affiliation(s)
- Ying-Ying Tsai
- Department of Physiology, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, United States
| | - William E Rainey
- Department of Physiology, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, United States
| | - Maribeth H Johnson
- Department of Biostatistics and Epidemiology, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, United States
| | - Wendy B Bollag
- Charlie Norwood VA Medical Center, One Freedom Way, Augusta, GA, 30904, United States; Department of Physiology, Medical College of Georgia at Augusta University, 1120 15th Street, Augusta, GA, 30912, United States.
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Abstract
Phospholipases are lipid-metabolizing enzymes that hydrolyze phospholipids. In some cases, their activity results in remodeling of lipids and/or allows the synthesis of other lipids. In other cases, however, and of interest to the topic of adrenal steroidogenesis, phospholipases produce second messengers that modify the function of a cell. In this review, the enzymatic reactions, products, and effectors of three phospholipases, phospholipase C, phospholipase D, and phospholipase A2, are discussed. Although much data have been obtained concerning the role of phospholipases C and D in regulating adrenal steroid hormone production, there are still many gaps in our knowledge. Furthermore, little is known about the involvement of phospholipase A2, perhaps, in part, because this enzyme comprises a large family of related enzymes that are differentially regulated and with different functions. This review presents the evidence supporting the role of each of these phospholipases in steroidogenesis in the adrenal cortex.
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Affiliation(s)
- Wendy B Bollag
- Charlie Norwood VA Medical CenterOne Freedom Way, Augusta, GA, USA Department of PhysiologyMedical College of Georgia, Augusta University (formerly Georgia Regents University), Augusta, GA, USA
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5
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Abstract
Aldosterone is a steroid hormone synthesized in and secreted from the outer layer of the adrenal cortex, the zona glomerulosa. Aldosterone is responsible for regulating sodium homeostasis, thereby helping to control blood volume and blood pressure. Insufficient aldosterone secretion can lead to hypotension and circulatory shock, particularly in infancy. On the other hand, excessive aldosterone levels, or those too high for sodium status, can cause hypertension and exacerbate the effects of high blood pressure on multiple organs, contributing to renal disease, stroke, visual loss, and congestive heart failure. Aldosterone is also thought to directly induce end-organ damage, including in the kidneys and heart. Because of the significance of aldosterone to the physiology and pathophysiology of the cardiovascular system, it is important to understand the regulation of its biosynthesis and secretion from the adrenal cortex. Herein, the mechanisms regulating aldosterone production in zona glomerulosa cells are discussed, with a particular emphasis on signaling pathways involved in the secretory response to the main controllers of aldosterone production, the renin-angiotensin II system, serum potassium levels and adrenocorticotrophic hormone. The signaling pathways involved include phospholipase C-mediated phosphoinositide hydrolysis, inositol 1,4,5-trisphosphate, cytosolic calcium levels, calcium influx pathways, calcium/calmodulin-dependent protein kinases, diacylglycerol, protein kinases C and D, 12-hydroxyeicostetraenoic acid, phospholipase D, mitogen-activated protein kinase pathways, tyrosine kinases, adenylate cyclase, and cAMP-dependent protein kinase. A complete understanding of the signaling events regulating aldosterone biosynthesis may allow the identification of novel targets for therapeutic interventions in hypertension, primary aldosteronism, congestive heart failure, renal disease, and other cardiovascular disorders.
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Affiliation(s)
- Wendy B Bollag
- Charlie Norwood VA Medical Center, Augusta, Georgia; Department of Physiology, Medical College of Georgia at Georgia Regents University, Augusta, Georgia
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6
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Abstract
The purpose of this article is to review fundamentals in adrenal gland histophysiology. Key findings regarding the important signaling pathways involved in the regulation of steroidogenesis and adrenal growth are summarized. We illustrate how adrenal gland morphology and function are deeply interconnected in which novel signaling pathways (Wnt, Sonic hedgehog, Notch, β-catenin) or ionic channels are required for their integrity. Emphasis is given to exploring the mechanisms and challenges underlying the regulation of proliferation, growth, and functionality. Also addressed is the fact that while it is now well-accepted that steroidogenesis results from an enzymatic shuttle between mitochondria and endoplasmic reticulum, key questions still remain on the various aspects related to cellular uptake and delivery of free cholesterol. The significant progress achieved over the past decade regarding the precise molecular mechanisms by which the two main regulators of adrenal cortex, adrenocorticotropin hormone (ACTH) and angiotensin II act on their receptors is reviewed, including structure-activity relationships and their potential applications. Particular attention has been given to crucial second messengers and how various kinases, phosphatases, and cytoskeleton-associated proteins interact to ensure homeostasis and/or meet physiological demands. References to animal studies are also made in an attempt to unravel associated clinical conditions. Many of the aspects addressed in this article still represent a challenge for future studies, their outcome aimed at providing evidence that the adrenal gland, through its steroid hormones, occupies a central position in many situations where homeostasis is disrupted, thus highlighting the relevance of exploring and understanding how this key organ is regulated. © 2014 American Physiological Society. Compr Physiol 4:889-964, 2014.
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Affiliation(s)
- Nicole Gallo-Payet
- Division of Endocrinology, Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, and Centre de Recherche Clinique Étienne-Le Bel of the Centre Hospitalier Universitaire de Sherbrooke (CHUS), Sherbrooke, Quebec, Canada
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7
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Olala LO, Shapiro BA, Merchen TC, Wynn JJ, Bollag WB. Protein kinase C and Src family kinases mediate angiotensin II-induced protein kinase D activation and acute aldosterone production. Mol Cell Endocrinol 2014; 392:173-81. [PMID: 24859649 PMCID: PMC4120960 DOI: 10.1016/j.mce.2014.05.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/26/2014] [Accepted: 05/14/2014] [Indexed: 12/26/2022]
Abstract
Recent evidence has shown a role for the serine/threonine protein kinase D (PKD) in the regulation of acute aldosterone secretion upon angiotensin II (AngII) stimulation. However, the mechanism by which AngII activates PKD remains unclear. In this study, using both pharmacological and molecular approaches, we demonstrate that AngII-induced PKD activation is mediated by protein kinase C (PKC) and Src family kinases in primary bovine adrenal glomerulosa cells and leads to increased aldosterone production. The pan PKC inhibitor Ro 31-8220 and the Src family kinase inhibitors PP2 and Src-1 inhibited both PKD activation and acute aldosterone production. Additionally, like the dominant-negative serine-738/742-to-alanine PKD mutant that cannot be phosphorylated by PKC, the dominant-negative tyrosine-463-to-phenylalanine PKD mutant, which is not phosphorylatable by the Src/Abl pathway, inhibited acute AngII-induced aldosterone production. Taken together, our results demonstrate that AngII activates PKD via a mechanism involving Src family kinases and PKC, to underlie increased aldosterone production.
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Affiliation(s)
- Lawrence O Olala
- Charlie Norwood VA Medical Center, Augusta, GA 30904, United States; Department of Physiology, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States
| | - Brian A Shapiro
- Institute of Molecular Medicine and Genetics, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States
| | - Todd C Merchen
- Department of Surgery, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States
| | - James J Wynn
- Department of Surgery, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States
| | - Wendy B Bollag
- Charlie Norwood VA Medical Center, Augusta, GA 30904, United States; Department of Physiology, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States; Departments of Cell Biology and Anatomy, Medicine and Orthopaedic Surgery, Medical College of Georgia at Georgia Regents University, Augusta, GA 30912, United States.
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Hattangady N, Olala L, Bollag WB, Rainey WE. Acute and chronic regulation of aldosterone production. Mol Cell Endocrinol 2012; 350:151-62. [PMID: 21839803 PMCID: PMC3253327 DOI: 10.1016/j.mce.2011.07.034] [Citation(s) in RCA: 206] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 07/11/2011] [Accepted: 07/17/2011] [Indexed: 11/28/2022]
Abstract
Aldosterone is the major mineralocorticoid synthesized by the adrenal and plays an important role in the regulation of systemic blood pressure through the absorption of sodium and water. Aldosterone production is regulated tightly by selective expression of aldosterone synthase (CYP11B2) in the adrenal outermost zone, the zona glomerulosa. Angiotensin II (Ang II), potassium (K(+)) and adrenocorticotropin (ACTH) are the main physiological agonists which regulate aldosterone secretion. Aldosterone production is regulated within minutes of stimulation (acutely) through increased expression and phosphorylation of the steroidogenic acute regulatory (StAR) protein and over hours to days (chronically) by increased expression of the enzymes involved in the synthesis of aldosterone, particularly CYP11B2. Imbalance in any of these processes may lead to several disorders of aldosterone excess. In this review we attempt to summarize the key molecular events involved in the acute and chronic phases of aldosterone secretion.
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Affiliation(s)
- Namita Hattangady
- Department of Physiology, Georgia Health Sciences University (formerly the Medical College of Georgia), 1120 15 Street, Augusta, GA 30912
| | - Lawrence Olala
- Department of Physiology, Georgia Health Sciences University (formerly the Medical College of Georgia), 1120 15 Street, Augusta, GA 30912
| | - Wendy B. Bollag
- Department of Physiology, Georgia Health Sciences University (formerly the Medical College of Georgia), 1120 15 Street, Augusta, GA 30912
- Charlie Norwood VA Medical Center, One Freedom Way, Augusta, GA 30904
| | - William E. Rainey
- Department of Physiology, Georgia Health Sciences University (formerly the Medical College of Georgia), 1120 15 Street, Augusta, GA 30912
- To whom correspondence should be addressed: William E. Rainey, Department of Physiology, Georgia Health Sciences University, 1120 15 Street, Augusta, GA 30912, , Tel: (706) 721-7665, Fax: (706) 721-7299
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9
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Qin H, Frohman MA, Bollag WB. Phospholipase D2 mediates acute aldosterone secretion in response to angiotensin II in adrenal glomerulosa cells. Endocrinology 2010; 151:2162-70. [PMID: 20219982 PMCID: PMC2869249 DOI: 10.1210/en.2009-1159] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In primary bovine adrenal glomerulosa cells, the signaling enzyme phospholipase D (PLD) is suggested to mediate priming, the enhancement of aldosterone secretion after pretreatment with and removal of angiotensin II (AngII), via the formation of persistently elevated diacylglycerol (DAG). To further explore PLD's role in priming, glomerulosa cells were pretreated with an exogenous bacterial PLD. Using this approach, phosphatidic acid (PA) is generated on the outer, rather than the inner, leaflet of the plasma membrane. Although PA is not readily internalized, the PA is nonetheless rapidly hydrolyzed by cell-surface PA phosphatases to DAG, which efficiently flips to the inner leaflet and accesses the cell interior. Pretreatment with bacterial PLD resulted in priming upon subsequent AngII exposure, supporting a role of DAG in this process, because the increase in DAG persisted after exogenous PLD removal. To determine the PLD isoform mediating aldosterone secretion, and presumably priming, primary glomerulosa cells were infected with adenoviruses expressing GFP, PLD1, PLD2, or lipase-inactive mutants. Overexpressed PLD2 increased aldosterone secretion by approximately 3-fold over the GFP-infected control under basal conditions, with a significant enhancement to about 16-fold over the basal value upon AngII stimulation. PLD activity was also increased basally and upon stimulation with AngII. In contrast, PLD1 overexpression had little effect on aldosterone secretion, despite the fact that PLD activity was enhanced. In both cases, the lipase-inactive PLD mutants showed essentially no effect on PLD activity or aldosterone secretion. Our results suggest that PLD2 is the isoform that mediates aldosterone secretion and likely priming.
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Affiliation(s)
- Haixia Qin
- Department of Physiology, Medical College of Georgia, Augusta, Georgia 30912-2630, USA
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10
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Chang HW, Wu VC, Huang CY, Huang HY, Chen YM, Chu TS, Wu KD, Hsieh BS. D4 dopamine receptor enhances angiotensin II-stimulated aldosterone secretion through PKC-epsilon and calcium signaling. Am J Physiol Endocrinol Metab 2008; 294:E622-9. [PMID: 18171914 DOI: 10.1152/ajpendo.00657.2007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aldosterone secretion is subjected to dopaminergic regulation. Our previous study showed that both human D2 and D4 dopamine receptors (D2R and D4R) modulate aldosterone secretion, but in opposing directions. The inhibitory effect of D2R is mediated by attenuating protein kinase C-micro (PKC-micro) and calcium-dependent signaling. The mechanism of D4R effect on angiotensin II (AII)-stimulated aldosterone secretion is explored in this study. Experiments were done with primary human adrenal cortical cells and human adrenocarcinoma (NCI-H295R) cells. Activation of different PKC isoforms was detected by specific phospho-PKC antibodies and PKC translocation. The role of calcium-dependent signaling was examined by measuring the cytoplasmic inositol 1,4,5-triphosphate (IP(3)) and calcium ([Ca(2+)](i)). The D4R agonist PD-168,077 enhanced AII-stimulated aldosterone synthesis and secretion as early as 30 min following exposure independently of the modulation of aldosterone synthase (CYP11B2) transcription. CYP11B2 mRNA level elevated by AII was augmented by D4R in the later period. These effects were reversed by the D4R antagonist L-745,870. AII activated PKC-alpha/betaII, -epsilon, and -micro but not PKC-delta, -theta, or -zeta/lambda of H295R cells. The D4R agonist selectively enhanced AII-stimulated PKC-epsilon phosphorylation and its translocation to the cell membrane. Furthermore, the D4R agonist enhanced the AII-stimulated elevation of intracellular IP(3) and [Ca(2+)](i). Inhibition of PKC-epsilon translocation by the PKC-epsilon-specific inhibitory peptide attenuated AII-stimulated aldosterone secretion, CYP11B2 mRNA expression, and elevation of intracellular IP(3) and [Ca(2+)](i). We conclude that D4R augmented aldosterone synthesis/secretion induced by AII. The mechanisms responsible for this augmentation are mediated through enhancing PKC-epsilon phosphorylation and [Ca(2+)](i) elevation.
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Affiliation(s)
- Hong-Wei Chang
- Nephrology Division, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
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Adenosine-stimulated adrenal steroidogenesis involves the adenosine A2A and A2B receptors and the Janus kinase 2–mitogen-activated protein kinase kinase–extracellular signal-regulated kinase signaling pathway. Int J Biochem Cell Biol 2008; 40:2815-25. [DOI: 10.1016/j.biocel.2008.05.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 05/15/2008] [Accepted: 05/29/2008] [Indexed: 11/22/2022]
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Getting SJ. Targeting melanocortin receptors as potential novel therapeutics. Pharmacol Ther 2006; 111:1-15. [PMID: 16488018 DOI: 10.1016/j.pharmthera.2005.06.022] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 06/21/2005] [Indexed: 10/25/2022]
Abstract
Adrenocorticotrophic hormone (ACTH(1-39)) and the melanocortins (alpha, beta and gamma-melanocyte-stimulating hormone [MSH]) are derived from a larger precursor molecule known as the pro-opiomelanocortin (POMC) protein. They exert their numerous biological effects by activating 7 transmembrane G-protein coupled receptors (GPCR), leading to adenylyl cyclase activation and subsequent cAMP accumulation within the target cell. To date, 5 melanocortin receptors (MCR) have been identified and termed MC1R to MC5R, they have been shown to have a wide and varied distribution throughout the body, being found in the central nervous system (CNS), periphery and immune cells. Melanocortins have a multitude of actions including: (i) modulating disease pathologies including arthritis, asthma, obesity; (ii) affecting functions, for example erectile dysfunction, skin tanning; and (iii) organ systems, for example cardiovascular system. Recently a mechanistic approach has been identified with alpha-MSH preventing NF-kappaB activation via the preservation and expression of IkappaBalphaprotein. This leads to a reduction of pro-inflammatory mediators including cytokines and inhibition of adhesion molecule expression, with subsequent reduction in leukocyte emigration. Development of selective ligands with an appropriate pharmacokinetic profile will enable a pharmacological evaluation of the potential beneficial effects of the melanocortins. In this review I have discussed the potential mechanistic action for the melanocortins and some of the disease pathologies shown to be modulated. This review proposes targeting the MCR with the ultimate aim of controlling many of the diseases that we face today.
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Affiliation(s)
- Stephen J Getting
- The William Harvey Research Institute, Charterhouse Square, London, EC1M 6BQ, United Kingdom.
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Kendirci M, Walls MM, Hellstrom WJG. Central Nervous System Agents in the Treatment of Erectile Dysfunction. Urol Clin North Am 2005; 32:487-501, vii. [PMID: 16291040 DOI: 10.1016/j.ucl.2005.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In the last two decades, a better understanding of the mechanisms governing erectile function and the pathophysiologies underlying erectile dysfunction (ED) have led re-searchers to investigate novel treatment concepts. Selective type-5 phosphodiesterase inhibitors are recommended as first-line therapy because of their high efficacy, but 30% to 40% of patients who have ED do not respond adequately to these agents and require alternative methods. The central nervous system plays a fundamental role in sexual behavior. Animal models have advanced our understanding of the neuroanatomic and neuropharmacologic basis of centrally induced penile erections. Clinical research with apomorphine has demonstrated efficacy in men who have a range of ED. Recent interest has focused on other centrally acting agents for ED treatment, including the melanocortin receptor agonists.
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Affiliation(s)
- Muammer Kendirci
- Department of Urology, Tulane University, Health Sciences Center, SL-42, New Orleans, LA 70112, USA
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Carroll L, Voisey J, van Daal A. Gene polymorphisms and their effects in the melanocortin system. Peptides 2005; 26:1871-85. [PMID: 15979205 DOI: 10.1016/j.peptides.2004.12.031] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 12/08/2004] [Indexed: 12/22/2022]
Abstract
In addition to its role in human pigmentation, components of the melanocortin system regulate appetite, energy homeostasis and hormone production. Recent studies have suggested possible roles of this system in immunity, transmission of pain signals, and reproductive potential. A number of polymorphisms have been identified in genes of the melanocortin system and are associated with pigmentation in humans, as well as being causative of disorders of adrenal hormone production and obesity. This review gives an outline of these polymorphisms, their functional significance and possible application to or impact on diagnosis and pharmacotherapy based on melanocortin pathways.
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Affiliation(s)
- Levi Carroll
- CRC for Diagnostics, Level 5, Q Block, Queensland University of Technology, 2 George St, Brisbane 4000, Australia
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Miranda TB, Lowenson JD, Clarke S. A new type of protein methylation activated by tyrphostin A25 and vanadate. FEBS Lett 2004; 577:181-6. [PMID: 15527782 DOI: 10.1016/j.febslet.2004.09.080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Accepted: 09/11/2004] [Indexed: 11/17/2022]
Abstract
It has been reported that S-adenosylmethionine-dependent protein methylation in rat kidney extracts can be greatly stimulated by tyrphostin A25, a tyrosine kinase inhibitor. We have investigated the nature of this stimulation. We find that addition of tyrphostin A25, in combination with the protein phosphatase inhibitor vanadate, leads to the stimulation of methylation of polypeptides of 64, 42, 40, 36, 31, and 15 kDa in cytosolic extracts of mouse kidney. The effect of tyrphostin appears to be relatively specific for the A25 species. The enhanced methylation does not represent the activity of the families of protein histidine, lysine or arginine methyltransferases, nor that of the l-isoaspartyl/d-aspartyl methyltransferase, enzymes responsible for the bulk of protein methylation in most cell types. Chemical and enzymatic analyses of the methylated polypeptides suggest that the methyl group is in an ester linkage to the protein. In heart extracts, we find a similar situation but here the stimulation of methylation is not dependent upon vanadate and an additional 18 kDa methylated species is found. In contrast, little or no stimulation of methylation is found in brain or testis extracts. This work provides evidence for a novel type of protein carboxyl methylation reaction that may play a role in signaling reactions in certain mammalian tissues.
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Affiliation(s)
- Tina Branscombe Miranda
- Department of Chemistry and Biochemistry, Molecular Biology Institute, UCLA, Los Angeles, CA 90095-1569, USA
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16
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Spät A, Hunyady L. Control of aldosterone secretion: a model for convergence in cellular signaling pathways. Physiol Rev 2004; 84:489-539. [PMID: 15044681 DOI: 10.1152/physrev.00030.2003] [Citation(s) in RCA: 344] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Aldosterone secretion by glomerulosa cells is stimulated by angiotensin II (ANG II), extracellular K(+), corticotrophin, and several paracrine factors. Electrophysiological, fluorimetric, and molecular biological techniques have significantly clarified the molecular action of these stimuli. The steroidogenic effect of corticotrophin is mediated by adenylyl cyclase, whereas potassium activates voltage-operated Ca(2+) channels. ANG II, bound to AT(1) receptors, acts through the inositol 1,4,5-trisphosphate (IP(3))-Ca(2+)/calmodulin system. All three types of IP(3) receptors are coexpressed, rendering a complex control of Ca(2+) release possible. Ca(2+) release is followed by both capacitative and voltage-activated Ca(2+) influx. ANG II inhibits the background K(+) channel TASK and Na(+)-K(+)-ATPase, and the ensuing depolarization activates T-type (Ca(v)3.2) Ca(2+) channels. Activation of protein kinase C by diacylglycerol (DAG) inhibits aldosterone production, whereas the arachidonate released from DAG in ANG II-stimulated cells is converted by lipoxygenase to 12-hydroxyeicosatetraenoic acid, which may also induce Ca(2+) signaling. Feedback effects and cross-talk of signal-transducing pathways sensitize glomerulosa cells to low-intensity stimuli, such as physiological elevations of [K(+)] (< or =1 mM), ANG II, and ACTH. Ca(2+) signaling is also modified by cell swelling, as well as receptor desensitization, resensitization, and downregulation. Long-term regulation of glomerulosa cells involves cell growth and proliferation and induction of steroidogenic enzymes. Ca(2+), receptor, and nonreceptor tyrosine kinases and mitogen-activated kinases participate in these processes. Ca(2+)- and cAMP-dependent phosphorylation induce the transfer of the steroid precursor cholesterol from the cytoplasm to the inner mitochondrial membrane. Ca(2+) signaling, transferred into the mitochondria, stimulates the reduction of pyridine nucleotides.
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Affiliation(s)
- András Spät
- Dept. of Physiology, Semmelweis University, Faculty of Medicine, PO Box 259, H-1444 Budapest, Hungary.
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Abstract
In the adrenal glomerulosa cell, aldosterone is synthesized from cholesterol, which is supplied to the cell and stored under the form of cholesterol esters, then hydrolyzed to be transferred to the mitochondrial outer membrane and finally transported to the inner membrane where the P450 side-chain cleavage enzyme will convert it to pregnenolone. Angiotensin II (AngII), one of the major physiological regulators of mineralocorticoid synthesis, appears to affect most of the steps along this cascade and thus to exert a powerful control over the use of cholesterol for aldosterone production.
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Affiliation(s)
- Alessandro M Capponi
- Division of Endocrinology, Diabetology and Nutrition, Faculty of Medicine, University Hospital, 24 rue Micheli-du-Crest, CH-1211 Geneva 14, Switzerland.
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18
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Soltoff SP. Evidence That Tyrphostins AG10 and AG18 Are Mitochondrial Uncouplers That Alter Phosphorylation-dependent Cell Signaling. J Biol Chem 2004; 279:10910-8. [PMID: 14688271 DOI: 10.1074/jbc.m305396200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Receptor agonists that initiate fluid secretion in salivary gland epithelial cells also increase protein phosphorylation. To assess contributions of tyrosine phosphorylation to secretion, changes in muscarinic receptor-initiated secretion (estimated from sodium pump-dependent increases in oxygen consumption) were measured in parotid acinar cells exposed to tyrosine kinase inhibitors. However, like the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxyphenyl hydrazone, tyrphostins AG10 and AG18 increased the rate of oxygen consumption and reduced cellular ATP by approximately 90% in the absence of the muscarinic agonist carbachol, indicating that these tyrphostins uncouple mitochondria. Exposure of isolated mitochondria to five structurally related tyrphostins demonstrated that their relative potencies as uncouplers differed from their in vitro kinase-inhibitory potencies due to different molecular requirements for the two effects. AG10 and AG18 blocked parotid phosphorylation events only at concentrations that reduced ATP content. The tyrosine kinase inhibitor genistein reduced ATP content by 15-20% and weakly uncoupled isolated mitochondria, but its inhibition of carbachol-mediated protein kinase Cdelta tyrosine phosphorylation and ERK1/2 activation appeared attributable to blocking tyrosine kinases directly. Carbachol itself rapidly reduced ATP content by 15-20%. Carbachol, 3'-O-(4-benzoyl)benzoyl adenosine 5'-triphosphate (P2X(7) receptor agonist), AG10, AG18, and carbonyl cyanide p-trifluoromethoxyphenyl hydrazone rapidly activated the fuel sensor AMP-activated protein kinase (AMPK); however, only AMPK activation by carbachol and BzATP was due to sodium pump stimulation. AG10 and AG18 also activated AMPK and/or uncoupled mitochondria in PC12, HeLa, and HEK293 cells. These studies demonstrate that some tyrosine kinase inhibitors produce cellular effects that are mechanistically different from their primary in vitro characterizations and, as do salivary secretory stimuli, promote rapid metabolic alterations that initiate secondary signaling events.
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Affiliation(s)
- Stephen P Soltoff
- Beth Israel Deaconess Medical Center, Division of Signal Transduction, Boston, Massachusetts 02215, USA
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19
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Abstract
The melanocortin system consists of melanocortin peptides derived from the proopiomelanocortin gene, five melanocortin receptors, two endogenous antagonists, and two ancillary proteins. This review provides an abbreviated account of the basic biochemistry, pharmacology, and physiology of the melanocortin system and highlights progress made in four areas. In particular, recent pharmacological and genetic studies have affirmed the role of melanocortins in pigmentation, inflammation, energy homeostasis, and sexual function. Development of selective agonists and antagonists is expected to further facilitate the investigation of these complex physiological functions and provide an experimental basis for new pharmacotherapies.
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Affiliation(s)
- Ira Gantz
- Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109-0682, USA.
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20
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Abstract
Adrenocortical carcinoma is a rare tumor that carries a very poor prognosis. Despite efforts to develop new therapeutic regimens to treat this disease, surgery remains the mainstay of treatment. Laboratory studies of adrenocortical cancers have revealed a wide variety of signaling pathways that can be altered in these neoplasms. Although ACTH signaling through adenylyl cyclase and protein kinase A is important for normal adrenal cellular physiology, there is evidence to suggest that this pathway may inhibit the growth of adrenocortical tumors, and that inactivation of the ACTH receptor may promote tumor formation. Although multiple signal transduction pathways are essential for normal adrenal growth and hormone secretion, efforts to identify events required for neoplastic transformation have met with limited success. Alterations that have frequently been observed in adrenocortical carcinoma include up-regulation of the IGF-II system, as well as mutations in TP53 and RAS. Current studies aim to elucidate the mechanisms of tumor growth by studying proproliferative signaling pathways, such as those involving Akt/PKB and the mitogen-activated protein kinases (MAPKs). Although studies of single pathways have been helpful in guiding investigations, new tools to study the integration and multiplicity of signaling pathways hold the hope of improved understanding of the signaling pathway alterations in adrenocortical cancer.
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Affiliation(s)
- Lawrence S Kirschner
- Unit on Genetics and Endocrinology, DEB, NICHD, National Instutes of Health, Bethesda, Maryland 20892-1862, USA
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21
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Lachowicz A, Rebas E. Gender differences in steroid modulation of angiotensin II-induced protein kinase C activity in anterior pituitary of the rat. Biochem Biophys Res Commun 2002; 294:95-100. [PMID: 12054746 DOI: 10.1016/s0006-291x(02)00433-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To investigate whether the various steroid hormones can modulate the basal and angiotensin II-induced protein kinase C (PKC) activity in the anterior pituitary of the rat, female and male intact and ovariectomized female Wistar rats were treated in vivo with estradiol (E2), progesterone (P), dehydroepiandrostendione sulfate (DHEA-S), and pregnenolone sulfate (PREG-S). Estradiol caused the increase of basal PKC activity in intact and ovariectomized females, but did not change the enzyme activity in males. In ovariectomized animals the increase of PKC activity was lower than in intact females. Progesterone decreased PKC activity only in intact animals. DHEA-S strongly enhanced activity of PKC in ovariectomized females. Pregnenolone sulfate did not significantly change PKC function of all studied groups. Incubation with AngII enhanced the PKC activity in intact (without steroid treatment) animals of both genders. In females, AngII and estradiol together rise the PKC-stimulated phosphorylation in greater degree than used separately. Treatment with other investigated steroids reduced the effect of AngII. In intact males every examined hormone turned back the stimulatory effect of AngII on PKC activity. These data suggest that gender differences in PKC activity are likely related to hormonal milieu of experimental animals and may depend in part on the basic plasma level of estrogens.
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Affiliation(s)
- Agnieszka Lachowicz
- Department of Experimental Endocrinology and Hormone Research, Institute of Endocrinology, Medical University of Łodź, Poland.
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22
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Abstract
Adrenomedullin (AM) was originally characterized in extracts of an adrenal medullary tumor. Since this original finding the peptide and its mRNA have also been found in the adrenal cortex, specifically, in the cells of the aldosterone-secreting zona glomerulosa. It is clear that the synthesis of AM is actively regulated in both cortex and medulla. Much research effort has been focused on identifying a role for AM in the adrenal gland. To date, no consistent effect on medullary catecholamine biosynthesis has been demonstrated. In the cortex the actions of AM are controversial and appear to depend on both the tissue preparation used and on the specific receptor population expressed in the individual gland. The results of further studies on the long-term actions of AM on adrenal growth and differentiation are awaited with interest.
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Affiliation(s)
- Supriya Kapas
- Molecular Signaling Group, Clinical Sciences Research Centre, Barts & the London, Queen Mary's School of Medicine & Dentistry, London E1 2AD, UK
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23
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Betancourt-Calle S, Jung EM, White S, Ray S, Zheng X, Calle RA, Bollag WB. Elevated K(+) induces myristoylated alanine-rich C-kinase substrate phosphorylation and phospholipase D activation in glomerulosa cells. Mol Cell Endocrinol 2001; 184:65-76. [PMID: 11694342 DOI: 10.1016/s0303-7207(01)00642-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Elevated extracellular potassium concentrations ([K(+)](e)) are known to stimulate aldosterone secretion from adrenal glomerulosa cells in vivo and in vitro. The mechanism is thought to involve depolarization-elicited activation of voltage-dependent calcium channels and an increase in calcium influx. Until now protein kinase C (PKC) was thought not to play a role in the steroidogenic response to elevated [K(+)](e). In this report, we provide evidence in bovine adrenal glomerulosa cells to suggest that elevated [K(+)](e) increases PKC activity, as shown by an enhancement in the phosphorylation of myristoylated alanine-rich C-kinase substrate (MARCKS). Elevated [K(+)](e)-induced MARCKS phosphorylation was delayed and transient and was not the result of a local production of angiotensin II (AngII). MARCKS phosphorylation in response to elevated [K(+)](e) was not accompanied by phosphoinositide hydrolysis but was inhibited by a selective PKC inhibitor. Elevated [K(+)](e) also activated phospholipase D (PLD) in a delayed but sustained manner. We propose that the observed PLD activation mediates the elevated [K(+)](e)-induced MARCKS phosphorylation via PKC, although other factors may modulate this phosphorylation event.
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Affiliation(s)
- S Betancourt-Calle
- Program in Cell Signaling, Department of Medicine, Institute of Molecular Medicine and Genetics, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912-2630, USA
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24
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Suga S, Wu J, Ogawa Y, Takeo T, Kanno T, Wakui M. Phorbol ester impairs electrical excitation of rat pancreatic beta-cells through PKC-independent activation of KATP channels. BMC Pharmacol 2001; 1:3. [PMID: 11560763 PMCID: PMC55693 DOI: 10.1186/1471-2210-1-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2001] [Accepted: 08/16/2001] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Phorbol 12-myristate 13-acetate (PMA) is often used as an activating phorbol ester of protein kinase C (PKC) to investigate the roles of the kinase in cellular functions. Accumulating lines of evidence indicate that in addition to activating PKC, PMA also produces some regulatory effects in a PKC-independent manner. In this study, we investigated the non-PKC effects of PMA on electrical excitability of rat pancreatic beta-cells by using patch-clamp techniques. RESULTS In current-clamp recording, PMA (80 nM) reversibly inhibited 15 mM glucose-induced action potential spikes superimposed on a slow membrane depolarization and this inhibition can not be prevented by pre-treatment of the cell with a specific PKC inhibitor, bisindolylmaleimide (BIM, 1 microM). In the presence of a subthreshold concentration (5.5 mM) of glucose, PMA hyperpolarized beta-cells in a concentration-dependent manner (0.8-240 nM), even in the presence of BIM. Based on cell-attached single channel recordings, PMA increased ATP-sensitive K+ channel (KATP) activity. Based on inside-out patch-clamp recordings, PMA had little effect on KATP activity if no ATP was in the bath, while PMA restored KATP activity that was suppressed by 10 microM ATP in the bath. In voltage-clamp recording, PMA enhanced tolbutamide-sensitive membrane currents elicited by repetitive ramp pulses from -90 to -50 mV in a concentration-dependent manner, and this potentiation could not be prevented by pre-treatment of cell with BIM. 4alpha-phorbol 12,13-didecanoate (4alpha-PDD), a non-PKC-activating phorbol ester, mimicked the effect of PMA on both current-clamp and voltage-clamp recording configurations. With either 5.5 or 16.6 mM glucose in the extracellular solution, PMA (80 nM) increased insulin secretion from rat islets. However, in islets pretreated with BIM (1 microM), PMA did not increase, but rather reduced insulin secretion. CONCLUSION In rat pancreatic beta-cells, PMA modulates insulin secretion through a mixed mechanism: increases insulin secretion by activation of PKC, and meanwhile decrease insulin secretion by impairing beta-cell excitability in a PKC-independent manner. The enhancement of KATP activity by reducing sensitivity of KATP to ATP seems to underlie the PMA-induced impairment of beta-cells electrical excitation in response to glucose stimulation.
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Affiliation(s)
- Sechiko Suga
- Department of Physiology, Hirosaki University School of Medicine, Hirosaki, 036-8562, Japan
| | - Jie Wu
- Devision of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013-4496, USA
| | - Yoshiji Ogawa
- The Third Department of Internal Medicine, Hirosaki University School of Medicine, Hirosaki, 036-8562, Japan
| | - Teruko Takeo
- Department of Physiology, Hirosaki University School of Medicine, Hirosaki, 036-8562, Japan
| | - Takahiro Kanno
- Department of Physiology, Hirosaki University School of Medicine, Hirosaki, 036-8562, Japan
| | - Makoto Wakui
- Department of Physiology, Hirosaki University School of Medicine, Hirosaki, 036-8562, Japan
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25
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Calle RA, Bollag WB, White S, Betancourt-Calle S, Kent P. ANPs effect on MARCKS and StAR phosphorylation in agonist-stimulated glomerulosa cells. Mol Cell Endocrinol 2001; 177:71-9. [PMID: 11377822 DOI: 10.1016/s0303-7207(01)00454-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Atrial natriuretic peptide (ANP) is a cardiac hormone that inhibits aldosterone secretion induced by all physiologic agonists. The purpose of this study is to explore ANP-induced changes in the phosphorylation of myristoylated alanine-rich C-kinase substrate (MARCKS) and the steroidogenic acute regulatory protein (StAR), in AngII or K(+)-stimulated glomerulosa cells. The data show that ANP completely inhibits the phosphorylation of MARCKS and partially inhibits that of StAR in cells stimulated with K(+). ANP also partially inhibits MARCKS phosphorylation but does not affect StAR phosphorylation in cells stimulated with AngII. These effects appear to be cGMP-independent and at least partially dependent on inhibition of protein kinase C (PKC). To our knowledge, this is the first report of ANP modulating either MARCKS or StAR phosphorylation in [(32)P]-labeled cells. The data also support the hypothesis that ANP inhibits aldosterone secretion acting as a step involved in cholesterol transport to the mitochondria.
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Affiliation(s)
- R A Calle
- Program in Cell Signaling, Institute of Molecular Medicine and Genetics, Medical College of Georgia, CB-2801, 1120 15th Street, Augusta, GA 30912, USA.
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26
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Abstract
Sixty years after its initial discovery, the octapeptide hormone angiotensin II (AngII) has proved to play numerous physiological roles that reach far beyond its initial description as a hypertensive factor. In spite of the host of target tissues that have been identified, only two major receptor subtypes, AT1 and AT2, are currently fully identified. The specificity of the effects of AngII relies upon numerous and complex intracellular signaling pathways that often mobilize calcium ions from intracellular stores or from the extracellular medium. Various types of calcium channels (store- or voltage-operated channels) endowed with distinct functional properties play a crucial role in these processes. The activity of these channels can be modulated by AngII in a positive and/or negative fashion, depending on the cell type under observation. This chapter reviews the main characteristics of AngII receptor subtypes and of the various calcium channels as well as the involvement of the multiple signal transduction mechanisms triggered by the hormone in the cell-specific modulation of the activity of these channels.
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Affiliation(s)
- M F Rossier
- Department of Internal Medicine, University Hospital, Geneva, Switzerland
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27
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Yingst DR, Davis J, Schiebinger R. Inhibitors of tyrosine phosphatases block angiotensin II inhibition of Na(+) pump. Eur J Pharmacol 2000; 406:49-52. [PMID: 11011032 DOI: 10.1016/s0014-2999(00)00664-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To determine how angiotensin II inhibits the Na(+) pump (Na(+), K(+)-ATPase) in rat zona glomerulosa, we selectively blocked signaling proteins that could be activated by the angiotensin AT(1) receptor and known to affect Na(+) pump activity. Inhibitors of protein kinase C [calphostin C (1 microM); staurosporine (1 microM)], phospholipase A(2) [arachidonyl triflouromethyl ketone (25 microM); quinacrine (75 microM)], diacylgycerol lipase [RHC-80267 (5 microM)], and tyrosine phosphorylation [tyrphostin 47 (100 microM)] had no effect on angiotensin II inhibition of the Na(+) pump. On the other hand, inhibitors of tyrosine phosphatases [phenylarsine oxide (5 microM) and 4-bromotetramisole oxalate (100 microM)] blocked angiotensin II inhibition, where as inhibitors of serine/threonine phosphatases [okadaic acid (1 microM) and microcystin (1.5 microM)] did not. Thus, angiotensin II inhibition of the Na(+) pump may in part be mediated by a tyrosine phosphatase.
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Affiliation(s)
- D R Yingst
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield Avenue, Detroit, MI 48201-1928, USA.
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28
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Lachowicz A, Ocedalski T, Pawlikowski M, Rebas E. Effect of 17-beta-estradiol and progesterone on angiotensin II-induced changes in inositol-1,4,5-trisphosphate content and protein kinase C activity in anterior pituitary. Biochem Biophys Res Commun 2000; 275:7-10. [PMID: 10944431 DOI: 10.1006/bbrc.2000.3272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Angiotensin II (AngII) is known to act in the anteriorpituitary through phosphatidiloinositol breakdown, increasing the level of inositol-1,4,5-trisphosphate (IP(3)) and diacyloglycerol (DAG), a potential activator of protein kinase C (PKC). We examined the effect of estradiol and progesterone treatment in vivo on IP(3) levels and activity of PKC under the influence of AngII. Three groups of intact female rats received in vivo injections of 17-beta-estradiol, progesterone, and oil (control) for five days, and then the in vitro effect of AngII was examined using homogenate of the anterior pituitary. AngII increased either the IP(3) concentration or the synapsin I phosphorylation catalyzed by PKC. Estradiol enhanced the basal (without AngII) IP(3) level and PKC activity induced by AngII. Progesterone did not change the basal and AngII-induced IP(3) concentrations. On the other hand, it decreased the basal PKC activity and blocked the effect of AngII. Our data suggest that ovarian steroids can modulate the effect of AngII on the anterior pituitary gland.
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Affiliation(s)
- A Lachowicz
- Department of Experimental Endocrinology and Hormone Research, Institute of Endocrinology, Institute of Obstetrics and Gynecology, Dr. Sterling Str. 3, Lódz, 91-425, Poland
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29
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Kigoshi T, Imaizumi N, Yoshida J, Nakagawa A, Nakano S, Nishio M, Uchida K. Involvement of tyrosine kinase in citrate-stimulated aldosterone production in bovine glomerulosa cells. Am J Physiol Endocrinol Metab 2000; 279:E140-5. [PMID: 10893333 DOI: 10.1152/ajpendo.2000.279.1.e140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed to assess whether citrate stimulates aldosterone production by isolated bovine adrenal glomerulosa cells in vitro. When the cells were incubated with graded concentrations of citrate up to 4.0 mM, basal aldosterone production was significantly elevated, with a gradual reduction of extracellular ionized calcium concentration. Without citrate, however, adding increasing amounts of calcium chloride to a calcium-free medium did not reproduce the citrate's effect on basal aldosterone production. Genistein, an inhibitor of tyrosine kinases, inhibited the citrate (4 mM)-induced aldosterone production in a dose-dependent manner, with 89.8% of inhibition at a concentration of 10 microM. When the cells were exposed to citrate (4 mM) for 5, 10, and 30 min, tyrosine in Mr 105,000 endogenous protein was dominantly phosphorylated. This study demonstrates for the first time that citrate stimulates aldosterone production in bovine adrenal glomerulosa cells in vitro and also suggests a crucial involvement of protein tyrosine kinase in the steroidogenic action of citrate in the cells.
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Affiliation(s)
- T Kigoshi
- Division of Endocrinology, Department of Internal Medicine, Kanazawa Medical University, Ishikawa 920-02, Japan
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30
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Slominski A, Wortsman J, Luger T, Paus R, Solomon S. Corticotropin releasing hormone and proopiomelanocortin involvement in the cutaneous response to stress. Physiol Rev 2000; 80:979-1020. [PMID: 10893429 DOI: 10.1152/physrev.2000.80.3.979] [Citation(s) in RCA: 559] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The skin is a known target organ for the proopiomelanocortin (POMC)-derived neuropeptides alpha-melanocyte stimulating hormone (alpha-MSH), beta-endorphin, and ACTH and also a source of these peptides. Skin expression levels of the POMC gene and POMC/corticotropin releasing hormone (CRH) peptides are not static but are determined by such factors as the physiological changes associated with hair cycle (highest in anagen phase), ultraviolet radiation (UVR) exposure, immune cytokine release, or the presence of cutaneous pathology. Among the cytokines, the proinflammatory interleukin-1 produces important upregulation of cutaneous levels of POMC mRNA, POMC peptides, and MSH receptors; UVR also stimulates expression of all the components of the CRH/POMC system including expression of the corresponding receptors. Molecular characterization of the cutaneous POMC gene shows mRNA forms similar to those found in the pituitary, which are expressed together with shorter variants. The receptors for POMC peptides expressed in the skin are functional and include MC1, MC5 and mu-opiate, although most predominant are those of the MC1 class recognizing MSH and ACTH. Receptors for CRH are also present in the skin. Because expression of, for example, the MC1 receptor is stimulated in a similar dose-dependent manner by UVR, cytokines, MSH peptides or melanin precursors, actions of the ligand peptides represent a stochastic (predictable) nonspecific response to environmental/endogenous stresses. The powerful effects of POMC peptides and probably CRH on the skin pigmentary, immune, and adnexal systems are consistent with stress-neutralizing activity addressed at maintaining skin integrity to restrict disruptions of internal homeostasis. Hence, cutaneous expression of the CRH/POMC system is highly organized, encoding mediators and receptors similar to the hypothalamic-pituitary-adrenal (HPA) axis. This CRH/POMC skin system appears to generate a function analogous to the HPA axis, that in the skin is expressed as a highly localized response which neutralizes noxious stimuli and attendant immune reactions.
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Affiliation(s)
- A Slominski
- Department of Pathology, Loyola University Medical Center, Maywood, Illinois, USA
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31
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Andreis PG, Markowska A, Champion HC, Mazzocchi G, Malendowicz LK, Nussdorfer GG. Adrenomedullin enhances cell proliferation and deoxyribonucleic acid synthesis in rat adrenal zona glomerulosa: receptor subtype involved and signaling mechanism. Endocrinology 2000; 141:2098-104. [PMID: 10830296 DOI: 10.1210/endo.141.6.7508] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effect of adrenomedullin (ADM) on the proliferative activity of the rat adrenal cortex has been investigated in vivo, using an in situ perfusion technique of the intact left gland. ADM and other chemicals were dissolved in the perfusion medium, and the perfusion was continued for 180 min. ADM infusion concentration dependently increased the mitotic index and [3H]thymidine incorporation into DNA in the zona glomerulosa (ZG; the maximal effective concentration was 10(-8) M), but not in inner adrenocortical layers, where basal proliferative activity was negligible. The effect of 10(-8) M ADM was equipotently counteracted by both the calcitonin gene-related peptide (CGRP) type 1 receptor antagonist CGRP-(8-37) and ADM-(22-52). The adenylate cyclase inhibitor SQ-22536 (10(-4) M), the cAMP blocker Rp-cAMP-S (10(-3) M), and the protein kinase A inhibitor H-89 (10(-5) M), although counteracting the ZG proliferogenic action of 10(-9) M ACTH, did not affect the 10(-8) M ADM-elicited increase in ZG DNA synthesis. Similar results were obtained using the phospholipase C inhibitor U-73122 (10(-5) M), the inositol-1,4,5-trisphosphate antagonist D,L-myo-inositol-1,4,5-trisphosphothiate (10(-4) M), and the protein kinase C inhibitor calphostin C (10(-5) M), which, however, significantly inhibited the ZG proliferogenic effect of 10(-9) M angiotensin II. The growth-promoting action of 10(-8) M ADM was not affected by the phospholipase A2 inhibitor AACOCF3 (10(-5) M), the cyclooxygenase (COX) inhibitor indomethacin (10(-5) M), or the mixed COX/lipoxygenase inhibitor phenidone (10(-5) M). In contrast, the ZG proliferogenic effect of 10(-8) M ADM was abolished by either the tyrosine kinase (TK) inhibitor tyrphostin-23 (10(-5) M) or the mitogen-activated protein kinase (MAPK) antagonists PD-98059 and U0216 (10(-4) M). ADM (10(-8) M) stimulated TK and p42/p44 MAPK activity in dispersed ZG, but not ZF, cells, and the effect was reversed by either 10(-6) M CGRP-(8-37) and ADM-(22-52) or preincubation with 10(-5) M tyrphostin-23. Collectively, our findings indicate that 1) ADM stimulates cell proliferation in the rat ZG, through CGRP-(8-37)- and ADM-(22-52)-sensitive receptors, probably of the CGRP1 subtype; and 2) the mitogenic effect of ADM is mediated by activation of the TK-MAPK cascade, without any involvement of the adenylate cyclase/protein kinase A-, phospholipase C/protein kinase C-, and COX- or lipoxygenase-dependent signaling pathways.
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Affiliation(s)
- P G Andreis
- Department of Human Anatomy and Physiology, University of Padua, Italy
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32
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Betancourt-Calle S, Bollag WB, Jung EM, Calle RA, Rasmussen H. Effects of angiotensin II and adrenocorticotropic hormone on myristoylated alanine-rich C-kinase substrate phosphorylation in glomerulosa cells. Mol Cell Endocrinol 1999; 154:1-9. [PMID: 10509794 DOI: 10.1016/s0303-7207(99)00111-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Angiotensin II (AngII) is thought to stimulate aldosterone secretion from bovine adrenal glomerulosa cells in part via activation of protein kinase C (PKC), while adrenocorticotropic hormone (ACTH) functions through increases in intracellular cAMP levels and calcium influx. Rather than using invasive homogenization techniques as in previous studies, we chose to monitor PKC activity in intact glomerulosa cells in situ by measuring the phosphorylation of the endogenous PKC substrate, myristoylated alanine-rich C-kinase substrate (MARCKS). AngII enhanced MARCKS phosphorylation in a rapid, sustained manner; whereas ACTH induced a rapid and sustained inhibition of MARCKS phosphorylation. Studies using pharmacological agents to mimic various signals indicated that the AngII-induced MARCKS phosphorylation was due to PKC activation, and the ACTH-elicited decrease was mediated by increases in calcium influx rather than cAMP production. We propose that changes in the phosphorylation state of MARCKS, an actin-binding protein, may contribute to cytoskeletal rearrangements involved in steroidogenesis.
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Affiliation(s)
- S Betancourt-Calle
- Department of Medicine, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta 30912-2630, USA
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33
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Ikegwuonu FI, Christou M, Jefcoate CR. Regulation of cytochrome P4501B1 (CYP1B1) in mouse embryo fibroblast (C3H10T1/2) cells by protein kinase C (PKC). Biochem Pharmacol 1999; 57:619-30. [PMID: 10037446 DOI: 10.1016/s0006-2952(98)00344-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The effects of co-treatment of C3H10T1/2 (10T1/2) cells with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 12-O-tetradecanoylphorbol-13-acetate (TPA) on the expression of the novel cytochrome P4501B1 (CYP1B1) were investigated. As monitored by CYP1B1-catalyzed 7,12-dimethylbenzanthracene (DMBA) metabolism, TPA suppressed basal and TCDD-induced DMBA metabolism in a concentration-dependent manner, with a maximum inhibitory concentration of 100 nM. The suppression of CYP1B1 catalytic activity occurred at two time points during which protein kinase C (PKC) was activated and down-regulated in these cells as judged by analyses of cellular PKC content and PKC-inhibitor (chelerythrine chloride)-influenced suppression of CYP1B1 catalytic activity. Experiments in which TCDD and benzanthracene (BA)-induced DMBA metabolism were monitored in PKCbeta1-overexpressing 10T1/2 cells revealed that the suppression of CYP1B1 activity is a consequence of cellular PKC elevation. This suppression phenomenon could be accounted for by PKC-mediated suppression of TCDD-induced CYP1B1 mRNA and apoprotein and of nuclear translocation of the Ah-receptor. In contrast, the mitogen-activated protein kinase (MAPK) proteins ERKs 1 and 2 were stimulated by TCDD under conditions in which PKC was activated. Collectively, our results suggest that PKC participates in the regulation of CYP1B1 in 10T1/2 cells, positively by directly suppressing the Ah-receptor signaling pathway, followed by an indirect or negative activation of the MAPK signaling pathway.
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Affiliation(s)
- F I Ikegwuonu
- Department of Pharmacology, University of Wisconsin Medical School, Madison 53706, USA
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Ciesla W. Can high maternal melatonin concentrations be responsible for inducing fetal pathologies, and can melatonin participate in immunohormonal homeostasis by determining prohormone convertase activity?--Hypothesis and facts. Med Hypotheses 1998; 51:269-80. [PMID: 9824829 DOI: 10.1016/s0306-9877(98)90046-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The hypothesis proposed here presents a mechanism of melatonin action, which may explain the role of this neurohormone in the genesis of various human pathologies, including fetal abnormalities. It assumes that monomeric or dimeric forms of indoloderived compounds such as melatonin and precursors of melanin have the ability to selectively stimulate the synthesis of prohormone 1 convertase (PC1) or prohormone 2 convertase (PC2), in proportion to their concentrations in the body. Thus, the mean circadian level of melatonin, by determining the manner and rapidity of proopiomelanocortin (POMC) cleavage, would also determine the mean proopiomelanocortin (POMC) level, maintained in dynamic equilibrium as a result of the simultaneous influence of testosterone, estradiol and cortisol on the intensity of POMC mRNA synthesis. The correlative proportions between the activity of PC1 and PC2 would therefore shape the character of hormonal balance in the organism, and in particular the mean ACTH concentration that determines the level of cyclic adenosine monophosphate (cAMP) concentration in its cells. The hypothesis also suggests that melatonin, by influencing the concentration of ACTH and beta-endorphin and their relative proportion could determine the stimulation or suppression of the immune system, thereby confirming its role as an immunomodulator. A disturbance in the above model of immunohormonal equilibrium, resulting from, for example, decreased pineal efficiency, would lead to stimulation of an alternative mode of achieving homeostasis, i.e. increase in concentration of melanin monomers and dimers, with concomitant high activity of tyrosine kinase and high cyclic guanosine monophosphate (cGMP) concentration in the cells. According to the proposed hypothesis, the risk of bearing a developmentally handicapped child would be highest in a woman with a high circadian secretion of melatonin, i.e. with domination of melatonin dimers and high PC1 activity, a condition which may be additionally aggravated by the exposure of the mother to adverse environmental factors or by immunohormonal disturbances. The hypothetical break-up of maternal melatonin dimers when crossing placenta would be the cause of excessive concentration of melatonin monomers and high PC2 activity in the fetus, and thus it should be the reason for very low levels of vimentin filaments and cAMP concentration in embryonal cells, the latter being directly responsible for inducing fetal pathologies.
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Affiliation(s)
- W Ciesla
- Department of Endocrinology, Sterling's Hospital, Medical University of Lódź, Poland.
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Synthesis and Biodistribution of (R,S)-[O-Methyl-11C]-1-[3-(5-Methoxy-1,2,3,4-tetrahydro-1-naphtalenyl)propyl]-4-Phenylpiperazine (PNU-157760), A Putative Radioligand for 5-HT1AReceptors. Bioorg Chem 1998. [DOI: 10.1006/bioo.1998.1089] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Mazzocchi G, Malendowicz LK, Gottardo G, Rebuffat P, Nussdorfer GG. Angiotensin-II stimulates DNA synthesis in rat adrenal zona glomerulosa cells: receptor subtypes involved and possible signal transduction mechanism. Endocr Res 1997; 23:191-203. [PMID: 9378106 DOI: 10.3109/07435809709031853] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Using an in situ perfusion technique of isolated left rat adrenal gland, it has been demonstrated that angiotensin-II (ANG-II) increases DNA synthesis in the zona glomerulosa (ZG), but not fasciculata-reticularis cells. The AT1 receptor antagonist DuP753 abolished the effect of ANG-II, while the AT2 receptor antagonist PD 123319 potentiated it. Both Ro31-8220, an inhibitor of protein kinase C (PKC), and tyrphostin-23, an inhibitor of tyrosine kinase (TK), evoked a partial reversal of ANG-II effect, and when added together to the perfusion medium abolished it. In contrast, the phospholipase C inhibitor U-73122 alone was able to induce a complete blockade of ANG-II effect. Neither the phospholipase A2 inhibitor AACOCF3 nor the cyclooxygenase inhibitor indomethacin and the lipoxygenase inhibitor phenidone affected ANG-II-induced stimulation of DNA synthesis, thereby making unlikely the involvement of the arachidonic acid signaling pathways. Our findings suggest that (i) ANG-II stimulates rat ZG cell proliferation acting via AT1 receptors coupled with phospholipase C, which activates both PKC and TK signaling systems; and (ii) the proliferogenic effect of ANG-II is partially counteracted by the activation of the AT2 receptor subtype.
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Affiliation(s)
- G Mazzocchi
- Department of Anatomy, University of Padua, Italy
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Mazzocchi G, Gottardo G, Nussdorfer GG. Effects of Somatostatin on Steroid Production by Adrenocortical Cells of the Domestic Turkey and Fowl. Zoolog Sci 1997. [DOI: 10.2108/zsj.14.359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Nussdorfer GG, Rossi GP, Belloni AS. The role of endothelins in the paracrine control of the secretion and growth of the adrenal cortex. INTERNATIONAL REVIEW OF CYTOLOGY 1997; 171:267-308. [PMID: 9066130 DOI: 10.1016/s0074-7696(08)62590-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Endothelins (ETs) are a family of vasoactive peptides (ET-1, ET-2, and ET-3) mainly secreted by vascular endothelium and widely distributed in the various body systems, where they play major autocrine/paracrine regulatory functions, acting via two subtypes of receptors (ETA and ETB): Adrenal cortex synthesizes and releases ETS and expresses both ETA and ETB. Zona glomerulosa possesses both ETA and ETB, whereas zona fasciculata/reticularis is almost exclusively provided with ETB. ETS exert a strong mineralocorticoid and a less intense glucocorticoid secretagogue action, mainly via ETB receptors. ETS also appear to enhance the growth and steroidogenic capacity of zona glomerulosa and to stimulate its proliferative activity. This trophic action of ETS is likely to be mediated mainly by ETA receptors. The intraadrenal release of ETS undergoes a multiple regulation, with the rise in blood flow rate and the local release of nitric oxide being the main stimulatory factors. Data are also available that indicate that ETS may also have a role in the pathophysiology of primary aldosteronism caused by adrenal adenomas and carcinomas.
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Premdas PD, Metcalfe CD. Regulation of protein kinase C and ornithine decarboxylase in the epidermis of juvenile white suckers (Catostomus commersoni) by 12-O-tetradecanoylphorbol-13-acetate, 17 α-ethinylestradiol and testosterone. Comp Biochem Physiol B Biochem Mol Biol 1996. [DOI: 10.1016/s0305-0491(96)00133-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Wheeler-Jones CP, May MJ, Morgan AJ, Pearson JD. Protein tyrosine kinases regulate agonist-stimulated prostacyclin release but not von Willebrand factor secretion from human umbilical vein endothelial cells. Biochem J 1996; 315 ( Pt 2):407-16. [PMID: 8615807 PMCID: PMC1217210 DOI: 10.1042/bj3150407] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The rapid synthesis and release of prostacyclin (PGI2) and the exocytotic secretion of von Willebrand Factor (vWF) elicited by activation of G-protein-coupled receptors on endothelium occur via signaling mechanisms which are incompletely defined. Activation of protein tyrosine kinases (PTKs) and modulation of the tyrosine-phosphorylation state of endogenous proteins have been implicated in several cellular processes including arachidonate release and exocytosis. In the present study we have examined the regulatory role of PTKs in agonist-stimulated release of PGI2 and vWF from human umbilical vein endothelial cells (HUVECs) using two chemically and mechanistically dissimilar PTK inhibitors (genistein and ST271). Genistein, but not the less active analogue daidzein, dose-dependently attenuated PGI2 release in response to thrombin and histamine (IC50 approx. 20 microM), and to the thrombin-receptor-activating peptide. A more potent inhibition of thrombin- and histamine-induced PGI2 synthesis was observed in cells exposed to ST271. In contrast, neither genistein nor ST271 modulated agonist-drive vWF secretion. At concentrations that abolished PGI2 release, genistein blocked thrombin- or histamine-evoked tyrosine phosphorylation of a 42 kDa protein. Ca2+ ionophore-induced PGI2 generation, but not vWF secretion, was also inhibited by both genistein and ST271, suggesting that these agents modulate PGI2 synthesis by acting at, or distal to, agonist-induced changes in intracellular CA2+ ([Ca2+]i). In fura-2-loaded HUVECs genistein partially reduced the histamine-induced peak [Ca2+]i but had no effect on the thrombin response. Ca(2+)-induced PGI2 release from electrically permeabilized HUVECs was abolished in the presence of ST271 or genistein, but not diadzein. The generation of PGI2 in response to exogenous arachidonic acid was not modulated by genistein or ST271, suggesting that PTK inhibitors do not directly inhibit cyclo-oxygenase activity. Taken together, these results suggest that PTKs regulate PGI2 synthesis and release in HUVECs by modulating, directly or indirectly, a CA(2+)-sensitive step upstream of cyclo-oxygenase.
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Affiliation(s)
- C P Wheeler-Jones
- Vascular Biology Research Centre, King's College London, Kensington, U.K
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Kapas S, Hinson JP. Inhibition of endothelin- and phorbol ester-stimulated tyrosine kinase activity by corticotrophin in the rat adrenal zona glomerulosa. Biochem J 1996; 313 ( Pt 3):867-72. [PMID: 8611168 PMCID: PMC1216991 DOI: 10.1042/bj3130867] [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: 01/31/2023]
Abstract
1. The experiments described in this study were carried out to investigate the role of tyrosine kinase in the acute adrenal response to peptide hormone stimulation, and to determine whether the activity of this kinase may be subject to regulation by other intracellular signalling mechanisms in the adrenal zona glomerulosa. 2. Previous studies from this laboratory have shown that angiotensin II stimulates tyrosine kinase activity in the rat adrenal cortex. This study has shown, for the first time, that endothelin-1 also stimulates tyrosine kinase activity in this tissue. 3. Using the specific inhibitor of protein kinase C (PKC) activity, Ro 31-8220, we have shown that stimulation of tyrosine kinase activity, in response to endothelin-1, angiotensin II or the phorbol ester phorbol 12-myristate 13-acetate, is at least partly dependent on increased PKC activity. 4. The data presented also provide further evidence of cross-talk between signalling systems in the adrenal cortex. Corticotrophin and its intracellular second messenger, cyclic AMP, significantly attenuate the increment in tyrosine kinase activity seen in response to each of the effectors used. 5. The results of this study provide important new evidence for the regulation of protein kinases by other intracellular second messenger systems.
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Affiliation(s)
- S Kapas
- Department of Biochemistry, Faculty of Medical Sciences, Queen Mary and Westfield College, London, U.K
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Barker S, Kapas S, Fluck RJ, Clark AJ. Effects of the selective protein kinase C inhibitor Ro 31-7549 on human angiotensin II receptor desensitisation and intracellular calcium release. FEBS Lett 1995; 369:263-6. [PMID: 7649269 DOI: 10.1016/0014-5793(95)00725-o] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mechanism underlying type I angiotensin II (Ang II) receptor (AT1 receptor) desensitisation is unknown. Structural features suggest it may be a substrate for protein kinase C (PKC). The effects of a selective PKC inhibitor, Ro 31-7549, on receptor desensitisation were investigated in CHO cells expressing the human AT1 receptor. Desensitisation was demonstrated with respect to the calcium response to Ang II in Fura-2-loaded cells. Ro 31-7549 had no effect on desensitisation. However, pretreatment with Ro 31-7549 caused a dose-dependent reduction in calcium release from intracellular stores. PKC may therefore act at a locus distal from the receptor itself.
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Affiliation(s)
- S Barker
- Department of Chemical Endocrinology, St. Bartholomew's Hospital Medical College, London, UK
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