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Silnitsky S, Rubin SJS, Zerihun M, Qvit N. An Update on Protein Kinases as Therapeutic Targets-Part I: Protein Kinase C Activation and Its Role in Cancer and Cardiovascular Diseases. Int J Mol Sci 2023; 24:17600. [PMID: 38139428 PMCID: PMC10743896 DOI: 10.3390/ijms242417600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/10/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Protein kinases are one of the most significant drug targets in the human proteome, historically harnessed for the treatment of cancer, cardiovascular disease, and a growing number of other conditions, including autoimmune and inflammatory processes. Since the approval of the first kinase inhibitors in the late 1990s and early 2000s, the field has grown exponentially, comprising 98 approved therapeutics to date, 37 of which were approved between 2016 and 2021. While many of these small-molecule protein kinase inhibitors that interact orthosterically with the protein kinase ATP binding pocket have been massively successful for oncological indications, their poor selectively for protein kinase isozymes have limited them due to toxicities in their application to other disease spaces. Thus, recent attention has turned to the use of alternative allosteric binding mechanisms and improved drug platforms such as modified peptides to design protein kinase modulators with enhanced selectivity and other pharmacological properties. Herein we review the role of different protein kinase C (PKC) isoforms in cancer and cardiovascular disease, with particular attention to PKC-family inhibitors. We discuss translational examples and carefully consider the advantages and limitations of each compound (Part I). We also discuss the recent advances in the field of protein kinase modulators, leverage molecular docking to model inhibitor-kinase interactions, and propose mechanisms of action that will aid in the design of next-generation protein kinase modulators (Part II).
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Affiliation(s)
- Shmuel Silnitsky
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
| | - Samuel J. S. Rubin
- Department of Medicine, School of Medicine, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA;
| | - Mulate Zerihun
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
| | - Nir Qvit
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel; (S.S.); (M.Z.)
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Saiyang X, Qingqing W, man X, Chen L, Min Z, Yun X, Wenke S, Haiming W, Xiaofeng Z, Si C, Haipeng G, Wei D, Qizhu T. Activation of Toll-like receptor 7 provides cardioprotection in septic cardiomyopathy-induced systolic dysfunction. Clin Transl Med 2021; 11:e266. [PMID: 33463061 PMCID: PMC7775988 DOI: 10.1002/ctm2.266] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 12/07/2020] [Accepted: 12/12/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND As a pattern recognition receptor, Toll-like receptor 7 (TLR7) widely presented in the endosomal membrane of various cells. However, the precise role and mechanism of TLR7 in septic cardiomyopathy remain unknown. This study aims to determine the role of TLR7 in cardiac dysfunction during sepsis and explore the mechanism of TLR7 in septic cardiomyopathy. METHODS We generated a mouse model of septic cardiomyopathy by challenging with lipopolysaccharide (LPS). TLR7-knockout (TLR7-/- ), wild-type (WT) mice, cardiac-specific TLR7-transgenic (cTG-TLR7) overexpression, and littermates WT (LWT) mice were subjected to septic model. Additionally, to verify the role and mechanism of TLR7 in vitro, we transfected neonatal rat ventricular myocytes (NRVMs) with Ad-TLR7 and TLR7 siRNA before LPS administration. The effects of TLR7 were assessed by Ca2+ imaging, western blotting, immunostaining, and quantitative real-time polymerase chain reaction (qPCR). RESULTS We found that TLR7 knockout markedly exacerbated sepsis-induced systolic dysfunction. Moreover, cardiomyocytes isolated from TLR7-/- mice displayed weaker Ca2+ handling than that in WT mice in response to LPS. Conversely, TLR7 overexpression alleviated LPS-induced systolic dysfunction, and loxoribine (TLR7-specific agonist) improved LPS-induced cardiac dysfunction. Mechanistically, these optimized effects were associated with enhanced the adenosine (cAMP)-protein kinase A (PKA) pathway, which upregulated phosphorylate-phospholamban (p-PLN) (Ser16) and promoted sarco/endoplasmic reticulum Ca2+ ATPase (Serca) and Ryanodine Receptor 2 (RyR2) expression in the sarcoplasmic reticulum (SR), and ultimately restored Ca2+ handling in response to sepsis. While improved Ca2+ handling was abrogated after H89 (a specific PKA inhibitor) pretreatment in cardiomyocytes isolated from cTG-TLR7 mice. Consistently, TLR7 overexpression improved LPS-induced Ca2+ -handling decrement in NRVMs. Nevertheless, TLR7 knockdown showed a deteriorative phenotype. CONCLUSIONS Our data demonstrated that activation of TLR7 protected against sepsis-induced cardiac dysfunction through promoting cAMP-PKA-PLN pathway, and we revealed that TLR7 might be a novel therapeutic target to block the septic cardiomyopathy and support systolic function during sepsis.
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Affiliation(s)
- Xie Saiyang
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Wu Qingqing
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Xu man
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Liu Chen
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Zhang Min
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Xing Yun
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Shi Wenke
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Wu Haiming
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Zeng Xiaofeng
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Chen Si
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
| | - Guo Haipeng
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of HealthQilu Hospital of Shandong UniversityJinanChina
- Department of Critical Care MedicineQilu Hospital of Shandong UniversityJinanPeople's Republic of China
| | - Deng Wei
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
- Department of CardiologyThe Fifth Affiliated Hospital of Xinjiang Medical UniversityÜrümqiChina
| | - Tang Qizhu
- Department of CardiologyRenmin Hospital of Wuhan UniversityWuhanPeople's Republic of China
- Hubei Key Laboratory of Metabolic and Chronic DiseasesWuhanPeople's Republic of China
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Joyce W, Scholman KT, Jensen B, Wang T, Boukens BJ. α 1-adrenergic stimulation increases ventricular action potential duration in the intact mouse heart. Facets (Ott) 2021. [DOI: 10.1139/facets-2020-0081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of α1-adrenergic receptors (α-ARs) in the regulation of myocardial function is less well-understood than that of β-ARs. Previous reports in the mouse heart have described that α1-adrenergic stimulation shortens action potential duration in isolated cells or tissues, in contrast to prolongation of the action potential reported in most other mammalian hearts. It has since become appreciated, however, that the mouse heart exhibits marked variation in inotropic response to α1-adrenergic stimulation between ventricles and even individual cardiomyocytes. We investigated the effects of α1-adrenergic stimulation on action potential duration at 80% of repolarization in the right and left ventricles of Langendorff-perfused mouse hearts using optical mapping. In hearts under β-adrenergic blockade (propranolol), phenylephrine or noradrenaline perfusion both increased action potential duration in both ventricles. The increased action potential duration was partially reversed by subsequent perfusion with the α-adrenergic antagonist phentolamine (1 μmol L−1). These data show that α1-receptor stimulation may lead to a prolonging of action potential in the mouse heart and thereby refine our understanding of how action potential duration adjusts during sympathetic stimulation.
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Affiliation(s)
- William Joyce
- Department of Biology—Zoophysiology, Aarhus University, DK-8000 Aarhus C, Denmark
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Koen T. Scholman
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 11005 AZ Amsterdam, the Netherlands
| | - Bjarke Jensen
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 11005 AZ Amsterdam, the Netherlands
| | - Tobias Wang
- Department of Biology—Zoophysiology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Bastiaan J. Boukens
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 11005 AZ Amsterdam, the Netherlands
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, 1100 DD Amsterdam, the Netherlands
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Abstract
Heart failure (HF) is a physiological state in which cardiac output is insufficient to meet the needs of the body. It is a clinical syndrome characterized by impaired ability of the left ventricle to either fill or eject blood efficiently. HF is a disease of multiple aetiologies leading to progressive cardiac dysfunction and it is the leading cause of deaths in both developed and developing countries. HF is responsible for about 73,000 deaths in the UK each year. In the USA, HF affects 5.8 million people and 550,000 new cases are diagnosed annually. Cardiac remodelling (CD), which plays an important role in pathogenesis of HF, is viewed as stress response to an index event such as myocardial ischaemia or imposition of mechanical load leading to a series of structural and functional changes in the viable myocardium. Protein kinase C (PKC) isozymes are a family of serine/threonine kinases. PKC is a central enzyme in the regulation of growth, hypertrophy, and mediators of signal transduction pathways. In response to circulating hormones, activation of PKC triggers a multitude of intracellular events influencing multiple physiological processes in the heart, including heart rate, contraction, and relaxation. Recent research implicates PKC activation in the pathophysiology of a number of cardiovascular disease states. Few reports are available that examine PKC in normal and diseased human hearts. This review describes the structure, functions, and distribution of PKCs in the healthy and diseased heart with emphasis on the human heart and, also importantly, their regulation in heart failure.
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Affiliation(s)
- Raphael M Singh
- School of Forensic and Applied Sciences, University of Central Lancashire, Preston, England, PR1 2HE, UK.
- Faculty of Medicine and Health Sciences, University of Guyana, Turkeyen, Georgetown, Guyana.
| | - Emanuel Cummings
- Faculty of Medicine and Health Sciences, University of Guyana, Turkeyen, Georgetown, Guyana
| | - Constantinos Pantos
- Department of Pharmacology, School of Medicine, University of Athens, Athens, Greece
| | - Jaipaul Singh
- School of Forensic and Applied Sciences, University of Central Lancashire, Preston, England, PR1 2HE, UK
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Bo L, Jiang L, Zhou A, Wu C, Li J, Gao Q, Zhang P, Lv J, Li N, Gu X, Zhu Z, Mao C, Xu Z. Maternal high-salt diets affected pressor responses and microvasoconstriction via PKC/BK channel signaling pathways in rat offspring. Mol Nutr Food Res 2015; 59:1190-9. [PMID: 25737272 DOI: 10.1002/mnfr.201400841] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/20/2015] [Accepted: 02/17/2015] [Indexed: 02/03/2023]
Abstract
SCOPE High-salt (HS) intake is linked to hypertension, and prenatal exposure to maternal HS diets may have long-term impact on cardiovascular systems. The relationship between HS diets and cardiovascular disease has received extensive attention. This study determined pressor responses and microvessel functions in the adult offspring rats exposed to prenatal HS. METHODS AND RESULTS The offspring of 5-month old as young adults in rats were used. Blood pressure, vascular tone, intracellular Ca(2+), and BK channels in mesenteric arteries were measured in the offspring. Phenylephrine (Phe)-induced pressor responses were significantly higher in the prenatal HS offspring. Vessel tension and intracellular Ca(2+) concentrations associated with Phe-induced pressor responses were increased in the mesenteric arteries of the HS offspring. PKC α- and δ-isoforms were upregulated in mesenteric arteries of the HS offspring. The enhanced Phe-mediated vascular activity was linked to the altered PKC-modulated BK channel functions. CONCLUSION The results suggested that prenatal exposure to HS altered microvascular activity probably via changes in PKC/BK signaling pathways, which may lead to increased risks of hypertension in the offspring.
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Affiliation(s)
- Le Bo
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Lin Jiang
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Anwen Zhou
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Chonglong Wu
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Jiayue Li
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Qinqin Gao
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Pengjie Zhang
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Juanxiu Lv
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Na Li
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Xiuxia Gu
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Zhoufeng Zhu
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Caiping Mao
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China
| | - Zhice Xu
- Institute for Fetology & Reproductive Medicine Center, First Hospital of Soochow University, Suzhou, P. R. China.,Center for Prenatal Biology, Loma Linda University, CA, USA
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Jeong MY, Walker JS, Brown RD, Moore RL, Vinson CS, Colucci WS, Long CS. AFos inhibits phenylephrine-mediated contractile dysfunction by altering phospholamban phosphorylation. Am J Physiol Heart Circ Physiol 2010; 298:H1719-26. [PMID: 20363890 DOI: 10.1152/ajpheart.00937.2009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Using neonatal rat ventricular myocytes, we previously reported that the expression of a dominant negative form of the c-Fos proto-oncogene (AFos) inhibited activator protein 1 activity and blocked the induction of the pathological gene profile stimulated by phenylephrine (PE) while leaving growth unaffected. We now extend these observations to the adult rat ventricular myocyte (ARVM) to understand the relationship between gene expression, growth, and function. Ventricular myocytes were isolated from adult rats and infected with adenovirus expressing beta-galactosidase (control) or AFos. The cells were subsequently treated with PE, and protein synthesis, gene program, calcium transients, and contractility were evaluated. As seen with the neonatal rat ventricular myocytes, in control cells PE stimulated an increase in protein synthesis, induced the pathological gene profile, and exhibited both depressed contractility and calcium transients. Although ARVMs expressing AFos still had PE-induced growth, pathological gene expression as well as contractility and calcium handling abnormalities were inhibited. To determine a possible mechanism of the preserved myocyte function in AFos-expressing cells, we examined phospholamban (PLB) and sarco(endo)plasmic reticulum calcium-ATPase proteins. Although there was no change in total PLB or sarco(endo)plasmic reticulum calcium-ATPase expression in response to PE treatment, PE decreased the phosphorylation of PLB at serine-16, an observation that was prevented in AFos-expressing cells. In conclusion, although PE-induced growth was unaffected in AFos-expressing ARVMs, the expression of the pathological gene profile was inhibited and both contractile function and calcium cycling were preserved. The inhibition of functional deterioration was, in part, due to the preservation of PLB phosphorylation.
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Affiliation(s)
- Mark Y Jeong
- University of Colorado Health Sciences Center, Aurora, Colorado, USA
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DAS DIPAKK, MORARU IONI, MAULIK NILANJANA, ENGELMAN RICHARDM. Gene Expression during Myocardial Adaptation to Ischemia and Reperfusion a. Ann N Y Acad Sci 2006. [DOI: 10.1111/j.1749-6632.1994.tb36735.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Iliodromitis EK, Tasouli A, Andreadou I, Bofilis E, Zoga A, Cokkinos P, Kremastinos DT. Intravenous atenolol and esmolol maintain the protective effect of ischemic preconditioning in vivo. Eur J Pharmacol 2005; 499:163-9. [PMID: 15363963 DOI: 10.1016/j.ejphar.2004.07.093] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Revised: 05/10/2004] [Accepted: 07/20/2004] [Indexed: 10/26/2022]
Abstract
Catecholamines bind to alpha- and beta-adrenoreceptors and are capable of preconditioning ischemic myocardium. Our purpose was to investigate the effect of acute either short or prolonged i.v. administration of beta-adrenoreceptor antagonists on ischemic preconditioning in vivo. Fifty-five anesthetized rabbits were divided into 10 groups (n=5-7 per group) and were subjected to 30-min regional ischemia of the heart after ligation of a prominent left coronary artery and 3-h reperfusion after releasing the snare. Ischemic preconditioning was obtained by three cycles of 5-min ischemia separated by 10-min reperfusion. beta-Adrenoreceptor blockade was obtained by the long acting beta-adrenoreceptor antagonist atenolol or by the short acting esmolol, which were given as a short 5-min infusion or as a prolonged 45-min infusion, starting respectively 20 min before and ending 15 min before the beginning of sustained ischemia, or starting 45 min before and ending immediately before the beginning of sustained ischemia. Atenolol was given at a rate of 0.2 mg min(-1) during 5 min or at a rate of 0.088 mg min(-1) as a 45-min infusion. Esmolol was given as an initial dose of 500 microg kg(-1) within 1 min, followed by a 4-min infusion at a rate of 50 microg kg(-1) min(-1) or as an initial dose of 3.4 mg within 1 min, followed by a 44-min infusion at a rate of 0.15 mg min(-1). Blood pressure and heart rate were continuously monitored. The infarcted and risk areas were delineated with the aid of tetrazolium chloride staining and fluorescent Zn-Cd particles. Infarct size was expressed in percent of the area at risk. All the animals without preconditioning developed an infarct size ranging between 36.3+/-2.4% and 49.6+/-7.6% (P=NS) and all the preconditioning groups developed an infarct size ranging between 14.9+/-1.2% and 21.0+/-2.2% (P=NS). All the preconditioning groups, independently of the use of beta-adrenoreceptor antagonists, had a smaller infarct size than the control group, which developed an infarct size of 47.3+/-2.5% (P<0.01). Intravenous atenolol and esmolol, independent of timing and mode of administration, does not seem to interfere with protection afforded by ischemic preconditioning in vivo.
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Affiliation(s)
- Efstathios K Iliodromitis
- 2nd Department of Cardiology, FESC, Onassis Cardiac Surgery Center, 356 Syngrou Ave, 176 74 Athens, Greece.
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Fan QI, Vanderpool K, Marsh JD. A 27 bp cis-acting sequence is essential for L-type calcium channel alpha(1C) subunit expression in vascular smooth muscle cells. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1577:401-11. [PMID: 12359330 DOI: 10.1016/s0167-4781(02)00441-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Expression of L-type calcium channels in cardiac myocytes and vascular smooth muscle cells (VSMC) critically regulates the contractile state of these cells. In order to discover the elements in the promoter region of the Ca(v)1.2 gene encoding the vascular/cardiac calcium channel alpha(1C) subunit that are important for the basal gene expression, approximately 2 kb of the 5'-flanking sequence of the Ca(v)1.2 gene has been cloned in our lab. In this study, using various lengths of the 5'-flanking DNA fused with a luciferase gene as a reporter, we have defined a 493-bp fragment of the cis-regulatory DNA which carries the majority of promoter activity in pulmonary artery smooth muscle (PAC1) cells. DNase I footprinting analysis of this 493-bp DNA using nuclear extracts from PAC1 cells revealed a 27-bp DNA sequence that contains a c-Ets like motif (CAGGATGC). Mutation of the Ets-like site and the respective flanking sequence within the DNase I footprinting protection region induced a marked change in the promoter activity in PAC1 cells. Electrophoretic mobility shift assays (EMSA) confirmed the presence of specific binding factor(s) in PAC1 cells' nuclear extracts for this 27-bp DNA. Competition studies with the wild-type and mutated DNA fragments established the importance of the 27 bp DNA sequence for high-affinity binding of the nuclear proteins to the promoter. We conclude that there is a 27 bp region in the promoter of the Ca(v)1.2 gene to which nuclear proteins from VSMC bind and strongly regulate the basal promoter activity.
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Affiliation(s)
- Q Ivy Fan
- Program in Molecular and Cellular Cardiology, Department of Internal Medicine, Wayne State University School of Medicine, 421 E. Canfield Avenue, Detroit, MI 48201, USA
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Salas MA, Vila-Petroff MG, Palomeque J, Aiello EA, Mattiazzi A. Positive inotropic and negative lusitropic effect of angiotensin II: intracellular mechanisms and second messengers. J Mol Cell Cardiol 2001; 33:1957-71. [PMID: 11708841 DOI: 10.1006/jmcc.2001.1460] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the cat ventricle angiotensin II exerts a positive inotropic effect produced by an increase in intracellular calcium associated with a prolongation of relaxation. The signaling cascades involved in these effects as well as the subcellular mechanisms of the negative lusitropic effect are still not clearly defined. The present study was directed to investigate these issues in cat papillary muscles and isolated myocytes. The functional suppression of the sarcoplasmic reticulum (SR) with either 0.5 microm ryanodine or 0.5 microm ryanodine plus 1 microm thapsigargin or the preincubation of the myocytes with the specific inhibitor of the inositol 1,4,5-triphosphate (IP3) receptors [diphenylborinic acid, ethanolamine ester (2-APB), 5-50 microm] did not prevent the positive inotropic effect and the increment in Ca2+ transient produced by 1 microm angiotensin II. In contrast, protein kinase C (PKC) inhibitors, chelerythrine (20 microm) and calphostin C (1 microm) completely inhibited both, the angiotensin II-induced increase in L-type calcium current and positive inotropic effect. The prolongation of half relaxation time produced by 0.5 microm angiotensin II [207+/-15.4 msec (control) to 235+/-19.98 msec (angiotensin II), P<0.05] was completely blunted by PKC inhibition. This antirelaxant effect, which was independent of intracellular pH changes, was associated with a prolongation of the action potential duration and was preserved after either the inhibition of the SR and the SR Ca2+ ATPase (ryanodine plus thapsigargin) or of the reverse mode of the Na+/Ca2+ exchanger (KB-R7943, 5 microm). We conclude that in feline myocardium the positive inotropic and negative lusitropic effects of angiotensin II are both entirely mediated by PKC without any significant participation of the IP3 limb of the phosphatidylinositol/phospholipase C cascade. The results suggest that the antirelaxant effect of angiotensin II might be determined by the decrease in Ca2+ efflux through the Na+/Ca2+ exchanger produced by the angiotensin II-induced prolongation of the action potential duration.
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Affiliation(s)
- M A Salas
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, La Plata, 1900, Argentina
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Abstract
Kappa-opioid receptor stimulation of the heart transiently increases twitch amplitude and decreases Ca2+-dependent actomyosin Mg2+-ATPase activity through an undetermined mechanism. One purpose of the present study was to determine if the increase in twitch amplitude is due to changes in myofilament Ca2+ sensitivity. We also wanted to determine if kappa-opioid receptor activation alters maximum actin-myosin ATPase activity and Ca2+ sensitivity of tension in a way consistent with protein kinase A or protein kinase C (PKC) action. Rat hearts were treated with U50,488H (a kappa-opioid receptor agonist), phenylephrine plus propranolol (alpha-adrenergic receptor stimulation), isoproterenol (a beta-adrenergic receptor agonist), or phorbol 12-myristate 13-acetate (PMA, receptor independent activator of PKC) or were untreated (control), and myofibrils were isolated. U50,488H, phenylephrine plus propranolol, and PMA all decreased maximum Ca2+-dependent actomyosin Mg2+-ATPase activity, whereas isoproterenol treatment increased maximum Ca2+-dependent actomyosin Mg2+- ATPase activity. Untreated myofibrils exposed to exogenous PKC-epsilon, but not PKC-delta, decreased maximum actomyosin Mg2+-ATPase activity. Langendorff-perfused hearts treated with U50,488H, phenylephrine plus propranolol, or isoproterenol had significantly higher ventricular ATP levels compared with control hearts. PKC inhibitors abolished the effects of U50,488H on Ca2+-dependent actomyosin Mg2+-ATPase activity and myocardial ATP levels. U50,488H and PMA treatment of isolated ventricular myocytes increased Ca2+ sensitivity of isometric tension compared with control myocytes at pH 7.0. The U50,488H-dependent increase in Ca2+ sensitivity of tension was retained at pH 6.6. Together, these findings are consistent with the hypotheses that 1) the positive inotropy associated with kappa-opioid receptor activation may be due in part to a PKC-mediated increase in myofilament Ca2+-sensitivity of tension and 2) the kappa-opioid receptor-PKC pathway is a modulator of myocardial energy status through reduction of actomyosin ATP consumption.
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Affiliation(s)
- W G Pyle
- Department of Physiology, University of Tennessee, Memphis, Tennessee 38163, USA
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Lester JW, Hofmann PA. Role for PKC in the adenosine-induced decrease in shortening velocity of rat ventricular myocytes. Am J Physiol Heart Circ Physiol 2000; 279:H2685-93. [PMID: 11087222 DOI: 10.1152/ajpheart.2000.279.6.h2685] [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: 11/22/2022]
Abstract
We previously demonstrated that both adenosine receptor activation and direct activation of protein kinase C (PKC) decrease unloaded shortening velocity (V(max)) of rat ventricular myocytes. The goal of this study was to further investigate a possible link among adenosine receptors, phosphoinositide-PKC signaling, and V(max) in rat ventricular myocytes. We determined that the adenosine receptor agonist R-phenylisopropyladenosine (R-PIA, 100 microM) and the alpha-adrenergic receptor agonist phenylephrine (Phe, 10 microM) increased turnover of inositol phosphates. PKC translocation from the cytosol to the sarcolemma was used as an indicator of PKC activation. Western blot analysis demonstrated an increased PKC-epsilon translocation after exposure to R-PIA, Phe, and the PKC activators dioctanoylglycerol (50 microM) and phorbol myristate acetate (1 microM). PKC-alpha, PKC-delta, and PKC-zeta did not translocate to the membrane after R-PIA exposure. Finally, PKC inhibitors blocked R-PIA-induced decreases in V(max) as well as Ca(2+)-dependent actomyosin ATPase in rat ventricular myocytes. These results support the conclusions that adenosine receptors activate phosphoinositide-PKC signaling and that adenosine receptor-induced PKC activation mediates a decrease in V(max) in ventricular myocytes.
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Affiliation(s)
- J W Lester
- Department of Physiology, University of Tennessee, Memphis, Tennessee 38163, USA
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15
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Layland J, Kentish JC. Effects of 1- or -adrenoceptor stimulation on work-loop and isometric contractions of isolated rat cardiac trabeculae. J Physiol 2000; 524 Pt 1:205-19. [PMID: 10747193 PMCID: PMC2269858 DOI: 10.1111/j.1469-7793.2000.t01-1-00205.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. We studied the effects of alpha1- or beta-adrenoceptor stimulation on the contractility of isolated rat ventricular trabeculae at 24 degrees C using the work-loop technique, which simulates the cyclical changes in length and force that occur during the cardiac cycle. Some muscles were injected with fura-2 to monitor the intracellular Ca2+ transient. 2. Comparison of twitch records revealed that peak force was greater and was reached earlier in work-loop contractions than in corresponding isometric contractions. This was attributed to the changes in muscle length and velocity during work-loop contractions, since the Ca2+ transients were largely unaffected by the length changes. 3. Stimulation of alpha1-adrenoceptors (with 100 microM phenylephrine) increased net work, power production, the frequency for maximum work, and the frequency for maximum power production (fopt). The increase in net work was due to the positive inotropic effect of phenylephrine, which was similar at all frequencies investigated (0. 33-4.5 Hz). The increase in fopt was attributed to an abbreviation of twitch duration induced by alpha1-stimulation at higher frequencies (> 1 Hz), even though the twitch became longer at 0.33 Hz. 4. beta-Adrenoceptor stimulation (with 5 microM isoprenaline) produced marked increases in net work, power output, the frequency for net work, and fopt. These effects were attributed both to the positive inotropic effect of beta-stimulation, which was greater at higher frequencies, and to the reduction in twitch duration. beta-stimulation also abolished the frequency-dependent acceleration of twitch duration. 5. The increase in power output and fopt with alpha1- as well as beta-adrenoceptor stimulation suggested that both receptor types may contribute to the effects of catecholamines, released during stress or exercise, although the greater effects of beta-stimulation are likely to predominate.
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Affiliation(s)
- J Layland
- Centre for Cardiovascular Biology and Medicine, Kings College London, St Thomas's Campus, Lambeth Palace Road, London SE1 7EH, UK.
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16
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Varma DR, Deng XF. Cardiovascular α1-adrenoceptor subtypes: functions and signaling. Can J Physiol Pharmacol 2000. [DOI: 10.1139/y99-142] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
α1-Adrenoceptors (α1AR) are G protein-coupled receptors and include α1A, α1B, and α1D subtypes corresponding to cloned α1a, α1b, and α1d, respectively. α1AR mediate several cardiovascular actions of sympathomimetic amines such as vasoconstriction and cardiac inotropy, hypertrophy, metabolism, and remodeling. α1AR subtypes are products of separate genes and differ in structure, G protein-coupling, tissue distribution, signaling, regulation, and functions. Both α1AAR and α1BAR mediate positive inotropic responses. On the other hand, cardiac hypertrophy is primarily mediated by α1AAR. The only demonstrated major function of α1DAR is vasoconstriction. α1AR are coupled to phospholipase C, phospholipase D, and phospholipase A2; they increase intracellular Ca2+ and myofibrillar sensitivity to Ca2+ and cause translocation of specific phosphokinase C isoforms to the particulate fraction. Cardiac hypertrophic responses to α1AR agonists might involve activation of phosphokinase C and mitogen-activated protein kinase via Gq. α1AR subtypes might interact with each other and with other receptors and signaling mechanisms.Key words: cardiac hypertrophy, inotropic responses, central α1-adrenoreceptors, arrythmias.
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17
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Ueyama T, Yoshida K, Senba E. Emotional stress induces immediate-early gene expression in rat heart via activation of alpha- and beta-adrenoceptors. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H1553-61. [PMID: 10516195 DOI: 10.1152/ajpheart.1999.277.4.h1553] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have studied the adrenergic mechanisms of immediate-early gene (IEG) induction in the discrete types of cardiac cells with the use of in situ hybridization histochemistry in an immobilization-stress model in conscious rats. Expression of c-fos, fos B, c-jun, jun B, NGFI-A, and NGFI-B mRNA was rapidly upregulated in the endothelial, myocardial, and smooth muscle cells of coronary vessels by 15-45 min after the onset of immobilization. Simultaneous blockade of both alpha- and beta-adrenoceptors completely abolished expression of IEGs in these cardiac cells. Application of an alpha-agonist or beta-agonist alone to the perfused rat heart under constant pressure elicited the upregulation of IEGs in a fashion similar to that of emotional stress. These data suggest that activation of either alpha- or beta-adrenoceptor is sufficient to evoke expression of these genes and that there may be cross talk in signal transduction downstream from alpha- and beta-adrenoceptors in cardiac cells.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic beta-Agonists/pharmacology
- Animals
- Coronary Vessels/cytology
- Coronary Vessels/physiology
- Endothelium, Vascular/physiology
- Gene Expression
- Genes, Immediate-Early/genetics
- Heart/drug effects
- Heart/physiology
- In Vitro Techniques
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/physiology
- Myocardium/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha/physiology
- Receptors, Adrenergic, beta/physiology
- Stress, Psychological/genetics
- Up-Regulation
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Affiliation(s)
- T Ueyama
- Department of Anatomy, Wakayama Medical College, Wakayama 641-8509, Japan.
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18
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Mounsey JP, Lu KP, Patel MK, Chen ZH, Horne LT, John JE, Means AR, Jones LR, Moorman JR. Modulation of Xenopus oocyte-expressed phospholemman-induced ion currents by co-expression of protein kinases. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1451:305-18. [PMID: 10556585 DOI: 10.1016/s0167-4889(99)00102-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Phospholemman (PLM), the major sarcolemmal substrate for phosphorylation by cAMP-dependent kinase (PKA) protein kinase C (PKC) and NIMA kinase in muscle, induces hyperpolarization-activated anion currents in Xenopus oocytes, most probably by enhancing endogenous oocyte currents. PLM peptides from the cytoplasmic tail are phosphorylated by PKA at S68, by NIMA kinase at S63, and by PKC at both S63 and S68. We have confirmed the phosphorylation sites in the intact protein, and we have investigated the role of phosphorylation in the regulatory activity of PLM using oocyte expression experiments. We found: (1) the cytoplasmic domain is not essential for inducing currents in oocytes; (2) co-expression of PKA increased the amplitude of oocyte currents and the amount of PLM in the oocyte membrane largely, but not exclusively, through phosphorylation of S68; (3) co-expression of PKA had no effect on a PLM mutant in which all putative phosphorylation sites had been inactivated by serine to alanine mutation (SSST 62, 63, 68, 69 AAAA); (4) co-expression of PKC had no effect in this system; (5) co-expression of NIMA kinase increased current amplitude and membrane protein level, but did not require PLM phosphorylation. These findings point to a role for phosphorylation in the function of PLM.
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Affiliation(s)
- J P Mounsey
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA.
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19
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Gruen M, Prinz H, Gautel M. cAPK-phosphorylation controls the interaction of the regulatory domain of cardiac myosin binding protein C with myosin-S2 in an on-off fashion. FEBS Lett 1999; 453:254-9. [PMID: 10405155 DOI: 10.1016/s0014-5793(99)00727-9] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Myosin binding protein C is a protein of the myosin filaments of striated muscle which is expressed in isoforms specific for cardiac and skeletal muscle. The cardiac isoform is phosphorylated rapidly upon adrenergic stimulation of myocardium by cAMP-dependent protein kinase, and together with the phosphorylation of troponin-I and phospholamban contributes to the positive inotropy that results from adrenergic stimulation of the heart. Cardiac myosin binding protein C is phosphorylated by cAMP-dependent protein kinase on three sites in a myosin binding protein C specific N-terminal domain which binds to myosin-S2. This interaction with myosin close to the motor domain is likely to mediate the regulatory function of the protein. Cardiac myosin binding protein C is a common target gene of familial hypertrophic cardiomyopathy and most mutations encode N-terminal subfragments of myosin binding protein C. The understanding of the signalling interactions of the N-terminal region is therefore important for understanding the pathophysiology of myosin binding protein C associated cardiomyopathy. We demonstrate here by cosedimentation assays and isothermal titration calorimetry that the myosin-S2 binding properties of the myosin binding protein C motif are abolished by cAMP-dependent protein kinase-mediated tris-phosphorylation, decreasing the S2 affinity from a Kd of approximately 5 microM to undetectable levels. We show that the slow and fast skeletal muscle isoforms are no cAMP-dependent protein kinase substrates and that the S2 interaction of these myosin binding protein C isoforms is therefore constitutively on. The regulation of cardiac contractility by myosin binding protein C therefore appears to be a 'brake-off' mechanism that will free a specific subset of myosin heads from sterical constraints imposed by the binding to the myosin binding protein C motif.
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Affiliation(s)
- M Gruen
- Max-Planck-Institute für molekulare Physiologie, Abt. Physikalische Biochemie, Dortmund, Germany
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20
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Meng X, Shames BD, Pulido EJ, Meldrum DR, Ao L, Joo KS, Harken AH, Banerjee A. Adrenergic induction of bimodal myocardial protection: signal transduction and cardiac gene reprogramming. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R1525-33. [PMID: 10233047 DOI: 10.1152/ajpregu.1999.276.5.r1525] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study tested the hypothesis that in vivo norepinephrine (NE) treatment induces bimodal cardiac functional protection against ischemia and examined the roles of alpha1-adrenoceptors, protein kinase C (PKC), and cardiac gene expression in cardiac protection. Rats were treated with NE (25 micrograms/kg iv). Cardiac functional resistance to ischemia-reperfusion (25/40 min) injury was examined 30 min and 1, 4, and 24 h after NE treatment with the Langendorff technique, and effects of alpha1-adrenoceptor antagonism and PKC inhibition on the protection were determined. Northern analysis was performed to examine cardiac expression of mRNAs encoding alpha-actin and myosin heavy chain (MHC) isoforms. Immunofluorescent staining was performed to localize PKC-betaI in the ventricular myocardium. NE treatment improved postischemic functional recovery at 30 min, 4 h, and 24 h but not at 1 h. Pretreatment with prazosin or chelerythrine abolished both the early adaptive response at 30 min and the delayed adaptive response at 24 h. NE treatment induced intranuclear translocation of PKC-betaI in cardiac myocytes at 10 min and increased skeletal alpha-actin and beta-MHC mRNAs in the myocardium at 4-24 h. These results demonstrate that in vivo NE treatment induces bimodal myocardial functional adaptation to ischemia in a rat model. alpha1-Adrenoceptors and PKC appear to be involved in signal transduction for inducing both the early and delayed adaptive responses. The delayed adaptive response is associated with the expression of cardiac genes encoding fetal contractile proteins, and PKC-betaI may transduce the signal for reprogramming of cardiac gene expression.
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Affiliation(s)
- X Meng
- Department of Surgery, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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21
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Kan H, Xie Z, Finkel MS. Norepinephrine-stimulated MAP kinase activity enhances cytokine-induced NO production by rat cardiac myocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H47-52. [PMID: 9887016 DOI: 10.1152/ajpheart.1999.276.1.h47] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of norepinephrine (NE) on cytokine-stimulated nitric oxide (NO) production by cardiac myocytes has not been previously reported. NE alone caused no significant increase in NO-2 levels over vehicle. Addition of NE to interleukin-1beta (IL-1beta) significantly increased inducible NO synthase (iNOS) mRNA expression, iNOS protein, and NO-2 production vs. IL-1beta alone. Addition of the alpha-adrenergic blocker prazosin or the beta-adrenergic blocker propranolol partially reduced the NE-mediated increase in iNOS mRNA expression and NO-2 production. Addition of prazosin and propranolol together completely abolished the NE-induced increase in iNOS mRNA expression and NO-2 production. NE significantly enhanced mitogen-activated protein (MAP) kinase activity that was reduced by prazosin, propranolol, and PD-98059, a selective MAP kinase kinase inhibitor. Addition of PD-98059 reduced the NE-mediated increase in iNOS mRNA expression and NO-2 production. We report for the first time that NE enhances IL-1beta-stimulated NO production by activation of alpha- and beta-adrenergic receptors through a novel MAP kinase mechanism.
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Affiliation(s)
- H Kan
- Department of Medicine, Morgantown, West Virginia 26506-9157, USA
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22
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Moorman JR, Jones LR. Phospholemman: a cardiac taurine channel involved in regulation of cell volume. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 442:219-28. [PMID: 9635035 DOI: 10.1007/978-1-4899-0117-0_28] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- J R Moorman
- University of Virginia, Charlottesville, USA
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23
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Abstract
Protein phosphorylation acts a pivotal mechanism in regulating the contractile state of the heart by modulating particular levels of autonomic control on cardiac force/length relationships. Early studies of changes in cardiac protein phosphorylation focused on key components of the excitation-coupling process, namely phospholamban of the sarcoplasmic reticulum and myofibrillar troponin I. In more recent years the emphasis has shifted towards the identification of other phosphoproteins, and more importantly, the delineation of the mechanistic and signaling pathways regulating the various known phosphoproteins. In addition to cAMP- and Ca(2+)-calmodulin-dependent kinase processes, these have included regulation by protein kinase C and the ever-emerging family of growth factor-related kinases such as the tyrosine-, mitogen- and stress-activated protein kinases. Similarly, the role of protein dephosphorylation by protein phosphatases has been recognized as integral in modulating normal cardiac cellular function. Recent studies involving a variety of cardiovascular pathologies have demonstrated that changes in the phosphorylation states of key cardiac regulatory proteins may underlie cardiac dysfunction in disease states. The emphasis of this comprehensive review will be on discussing the role of cardiac phosphoproteins in regulating myocardial function and pathophysiology based not only on in vitro data, but more importantly, from ex vivo experiments with corroborative physiological and biochemical evidence.
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Affiliation(s)
- S T Rapundalo
- Department of Biochemistry, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert, Ann Arbor, MI 48105, USA.
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24
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Endoh M. Differential Effects of Protein Kinase C Activators and Inhibitors on alpha- and beta-Adrenoceptor-mediated Positive Inotropic Effect in Isolated Rabbit Papillary Muscle. J Cardiovasc Pharmacol Ther 1997; 2:159-170. [PMID: 10684455 DOI: 10.1177/107424849700200303] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND: A number of novel agents that activate or inhibit protein kinase C (PKC) in vitro have been developed to evaluate the physiologic role of PKC in regulation of cellular function. However, most of the PKC inhibitors also affect the protein kinase A, and the effects of these agents in intact myocardium remain still controversial. The present study was carried out to examine the effects of these agents on the positive inotropic effect (PIE) medicated by alpha- and beta-adrenoceptors in isolated rabbit papillary muscle. METHODS AND RESULTS: A potent PKC activator, phorbol 12, 13-dibutyrate (PDBu) at 10 and 30 nM, induced a significant PIE. PDBu at 3 nM and higher inhibited the alpha-mediated PIE and abolished it at 100 nM without affecting the beta-mediated PIE. Phorbol 12-myrisate 13-acetate (PMA) and 1-oleyl-2-acetyl-sn-glycerol (OAG) elicited a similar selective inhibitory action on the alpha-mediated PIE. The PIE of PDBu was abolished by chelerythrine and partially inhibited by staurosporine, but H-7 or calphostin-C did not affect the PIE. These PKC inhibitors consistently inhibited the alpha-mediated PIE by 20-30% at concentrations that they did not affect the beta-mediated PIE. None of the PKC inhibitors influence the PDBu-induced inhibitory action on the alpha-mediated PIE, an indication that they failed to reach the site of the inhibitory action of PDBu. CONCLUSION: Selective modulation by the PKC activators and inhibitors of the alpha-mediated PIE with little effect on the beta-mediated PIE implies that the activation of PKC has a physiological relevance to the alpha-mediated PIE. However, the externally administered PKC activators do not mimic the effect of diacylglycerol that is generated endogenously by alpha-stimulation. By contrast, externally applied PKC inhibitors selectively antagonize the alpha-adrenoreceptor-mediated PIE in rabbit ventricular myocardium.
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25
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Nasa Y, Yabe K, Takeo S. Beta-adrenoceptor stimulation-mediated preconditioning-like cardioprotection in perfused rat hearts. J Cardiovasc Pharmacol 1997; 29:436-43. [PMID: 9156351 DOI: 10.1097/00005344-199704000-00002] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To determine whether adrenergic stimulation induces preconditioning-like cardioprotection, rat hearts were perfused for 2 min with either norepinephrine, phenylephrine, or isoproterenol followed by 10-min drug-free perfusion. Then the hearts were subjected to 40-min ischemia and 30-min reperfusion. Little recovery of left ventricular developed pressure (LVDP) and loss of the myocardial creatine kinase (CK) during reperfusion were observed in the drug-untreated heart. Preperfusion with norepinephrine (0.25 microM) or isoproterenol (0.25 microM), but not phenylephrine (10 microM), resulted in a better recovery of LVDP in the postischemic reperfused heart and a reduction in CK release during reperfusion. A similar improvement of postischemic cardiac contractile dysfunction and CK loss was seen in the heart subjected to 5-min ischemia followed by 5-min reperfusion (ischemic preconditioning) before the prolonged period of ischemia/reperfusion. Pretreatment with timolol, a beta-adrenoceptor blocker, abolished the protective effect of norepinephrine, whereas pretreatment with bunazosin, an alpha 1-adrenoceptor blocker, did not affect the protective effect of isoproterenol. The results suggest that a brief period of stimulation of cardiac beta-adrenoceptor exerts the preconditioning-mimetic protective effect against postischemic contractile dysfunction in perfused rat hearts.
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Affiliation(s)
- Y Nasa
- Department of Pharmacology, Tokyo University of Pharmacy and Life Science, Japan
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26
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Wientzek M, Allen BG, McDonald-Jones G, Katz S. Characterization of calcium-dependent forms of protein kinase C in adult rat ventricular myocytes. Mol Cell Biochem 1997; 166:11-23. [PMID: 9046017 DOI: 10.1023/a:1006861011857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The presence and subcellular localization of the Ca2+-dependent protein kinase C (PKC) isoforms alpha and beta were investigated in freshly isolated adult rat cardiac ventricular myocytes. PKC activity was measured in cytosolic and particulate fractions prepared from control myocytes and those treated with either phorbol ester (phorbol 12-myristate 13-acetate, PMA) or a permeant synthetic diacylglycerol analog (1-oleoyl-2-acetylglycerol, OAG) in the absence or presence of an inhibitor of diacylglycerol kinase activity, compound R59022. Preliminary studies detected no Ca2+-/phospholipid-dependent histone kinase activity in either subcellular fraction. To reproducibly observe Ca2+-/phospholipid-dependent protein kinase activity, partial purification using a MonoQ HR 5/5 column and the presence of the peptide inhibitor of the cAMP-dependent protein kinase were essential. MonoQ chromatography of cytosolic and particulate fractions resulted in three peaks of Ca2+/phospholipid-dependent protein kinase activity. In the cytosolic fraction a large peak of activity eluted at 230-300 mM NaCl. Isoform-specific antisera indicated both PKC alpha and PKC beta were present. In the particulate fraction two peaks of Ca2+-/phospholipid-dependent protein kinase activity, both containing PKCa immunoreactivity, were observed. The larger peak eluted at 230-300 mM NaCl. In addition, a peak eluting at lower salt concentrations contained a Ca2+-/phospholipid-independent histone kinase activity. This peak of kinase activity contained PKC alpha immunoreactive bands of 80- and 50-kDa. The 80-kDa band was the holoenzyme of PKC alpha whereas the band of lower molecular mass was likely a proteolytic fragment. In both cytosolic and particulate fractions, the peak of kinase activity eluting at 230-300 mM NaCl contained PKC alpha in the form of an 80-kDa doublet; this suggested the presence of autophosphorylated PKC. Incubation of the myocytes with PMA, but not OAG, resulted in translocation of PKC from the cytosolic to the particulate fraction. Curiously, a transient decrease in PKC activity was observed in both subcellular fractions following treatment with either OAG or ethanol (1%). Results from this study show that freshly isolated adult rat cardiac ventricular myocytes contain both PKC alpha and PKC beta, and that these isoforms translocate to the particulate fraction in response to treatment with PMA, but not OAG.
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Affiliation(s)
- M Wientzek
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
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27
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Affiliation(s)
- M Goto
- Department of Physiology, University of South Alabama, College of Medicine, Mobile 36688, USA
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28
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Allen BG, Katz S. Phosphorylation of cardiac junctional and free sarcoplasmic reticulum by PKC alpha, PKC beta, PKA and the Ca2+/calmodulin-dependent protein kinase. Mol Cell Biochem 1996; 155:91-103. [PMID: 8700163 DOI: 10.1007/bf00229306] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Phosphorylation of cardiac junctional and free sarcoplasmic reticulum (SR) by protein kinase C (PKC) isoforms alpha and beta was investigated. Both SR and PKC were isolated from canine heart. Junctional and free SR vesicles were prepared by calcium-phosphate-loading. The substrate specificities of PKC alpha and PKC beta were found to be similar in both SR fractions. A high molecular weight junctionally-associated protein was phosphorylated by PKA, PKC and an endogenous Ca2+/calmodulin-dependent protein kinase activity: the highest levels of phosphate incorporation being catalysed by the latter kinase. In addition to this high molecular weight junctionally-associated protein, PKC induced phosphorylation of 45, 96 kDa and several proteins of greater than 200 kDa in junctional SR. A protein of 96 kDa was phosphorylated by both isoforms in junctional and free SR. The major substrate for PKA, PKC alpha, PKC beta and the Ca2+/calmodulin-dependent protein kinase, in both junctional and free SR, was phospholamban. Although the phosphorylation of phospholamban by PKC was activated by Ca2+, a component of this activity appeared to be independent of Ca2+. PKC-mediated phosphorylation of phospholamban was fully activated by 1 microM Ca2+ whereas the Ca2+/calmodulin dependent kinase required concentrations in excess of 5 microM Ca2+. In the in vitro system employed in these studies, the concentrations of either PKC alpha or the catalytic subunit of PKA required to phosphorylate phospholamban were found to be similar. In addition, in the presence of a 15 kDa sarcolemmal-associated protein, which becomes phosphorylated upon activation of PKC in vivo, phosphorylation of phospholamban by PKC was unaffected. These results demonstrate that, although substrates for both subtypes are found in both junctional and free SR, PKC alpha and PKC beta do not show differences in selectivity towards these substrates.
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Affiliation(s)
- B G Allen
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
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29
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Cohen MV, Downey JM. Myocardial preconditioning promises to be a novel approach to the treatment of ischemic heart disease. Annu Rev Med 1996; 47:21-9. [PMID: 8712775 DOI: 10.1146/annurev.med.47.1.21] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In the phenomenon termed "ischemic preconditioning," a brief period of ischemia prior to a more prolonged one improves myocardial function (after reperfusion) and diminishes infarction. This phenomenon has been described extensively in experimental animals and now in humans. It is triggered by several agents released by ischemic cells and can be reproduced by infusion of agonists coupled to protein kinase C (PKC), e.g. adenosine, angiotensin, phenylephrine, bradykinin, and endothelin. The intracellular signaling pathway involves a phospholipase, either C or D, which metabolizes membrane phospholipids to produce diacylglycerol, a necessary endogenous cofactor for PKC activation. Which protein(s) is phosphorylated by PKC is not yet known, nor is the identity of the end-effector that actually mediates protection of the ischemic cell. Identification of the end-effector may make it possible in the routine treatment of patients with ischemic heart disease to precondition and thereby salvage ischemic myocardium and improve survival.
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Affiliation(s)
- M V Cohen
- Department of Medicine, University of South Alabama, College of Medicine, Mobile 36688, USA
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30
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Martinussen HJ. Myocardial contractile response and IP3, cAMP and cGMP interrelationships. Ups J Med Sci 1996; 101:1-33. [PMID: 8740925 DOI: 10.3109/03009739609178912] [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: 02/01/2023] Open
Abstract
An experimental study in the perfused working normal and pressure overloaded rat heart. A mini review based on a doctoral thesis.
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Affiliation(s)
- H J Martinussen
- Department of Anestesiology and Intensive Care, Uppsala University Hospital, Sweden
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31
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Martinussen HJ, Waldenström A, Ronquist G. Carbachol-induced increase in inositol trisphosphate (IP3) content is attenuated by adrenergic stimulation in the isolated working rat heart. ACTA PHYSIOLOGICA SCANDINAVICA 1995; 153:151-8. [PMID: 7778455 DOI: 10.1111/j.1748-1716.1995.tb09846.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The interrelated responses of concomitant adrenergic and muscarinic receptor stimulation on second messengers and mechanical activity in the isolated perfused working rat heart were studied. The hearts were perfused with Krebs-Henseleit buffer in a modified Langendorff apparatus. The hearts were perfused with noradrenaline (10(-6) mol L-1, n = 20), with carbachol (3 x 10(-7) mol L-1, n = 11) or with noradrenaline plus carbachol (n = 20) in the above-mentioned concentrations. The hearts were frozen at 20 s, 30 s and 40 min after addition of noradrenaline and noradrenaline plus carbachol and at 20 s and 40 min after addition of carbachol. Five hearts were freeze-clamped directly after preperfusion and another five hearts after 40 min of perfusion and used as controls. Myocardial cAMP increased at 20 s and 40 min after noradrenaline perfusion. In contrast to this cAMP was unchanged at 20 s and decreased at 40 min after perfusion with noradrenaline plus carbachol. IP3 content increased after 20 s of carbachol- and after 40 min of noradrenaline perfusion (P < 0.05). However, noradrenaline plus carbachol did not induced any significant increase in IP3 content after 20 s and 30 s, but after 40 min a decrease below basal level was found (P < 0.05). Noradrenaline stimulation attenuated muscarinic agonist induced IP3 formation. A reciprocity existed in that noradrenaline induced IP3 formation was attenuated by carbachol. No direct relationship was observed between the IP3 response and contractility, also valid for cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H J Martinussen
- Department of Anaesthesiology, University Hospital, Uppsala, Sweden
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32
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Affiliation(s)
- S F Steinberg
- Department of Medicine, Columbia University, New York, NY 10032, USA
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Vittone L, Mundiña-Weilenmann C, Mattiazzi A, Cingolani H. Physiologic and pharmacologic factors that affect myocardial relaxation. J Pharmacol Toxicol Methods 1994; 32:7-18. [PMID: 7833510 DOI: 10.1016/1056-8719(94)90011-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Evaluation of the myocardial relaxation has become important in the last years. An impaired relaxation may precede contractile dysfunctions and even cause heart failure. To treat this impaired lusitropism it is necessary to properly assess the lusitropic state of the heart and understand how drugs affect the cellular mechanisms underlying myocardial relaxation (sarcoplasmic reticulum function, Ca2+ fluxes through the sarcolemma and myofilament Ca2+ sensitivity). Current information regarding these issues is provided in this review. The relative usefulness of the mechanical parameters used to evaluate the lusitropic state of the heart in experimental models applied in pharmacology will also be discussed.
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Affiliation(s)
- L Vittone
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina
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Protein kinase C-mediated phosphorylation of troponin I and C-protein in isolated myocardial cells is associated with inhibition of myofibrillar actomyosin MgATPase. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53831-x] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Noland TA, Kuo JF. Protein kinase C phosphorylation of cardiac troponin T decreases Ca(2+)-dependent actomyosin MgATPase activity and troponin T binding to tropomyosin-F-actin complex. Biochem J 1992; 288 ( Pt 1):123-9. [PMID: 1445257 PMCID: PMC1132088 DOI: 10.1042/bj2880123] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Effects of phosphorylation of bovine cardiac troponin T (TnT) by protein kinase C on the Ca(2+)-stimulated MgATPase activity of reconstituted actomyosin complex and the binding of TnT to tropomyosin(Tm)-F-actin were investigated. The Ca(2+)-stimulated MgATPase of actomyosin containing phosphorylated TnT (1.8 mol of P/mol), compared with that containing unphosphorylated TnT, was decreased by up to 48%. Phosphorylation of TnT also decreased (up to 48%) its maximum binding to Tm-F-actin, which was accompanied by a decrease (up to 3.5-fold) in its apparent binding affinity. The findings indicate that the effects of phosphorylated TnT in decreasing actomyosin MgATPase might be secondary to its decreased interactions with the other components of the thin filament, representing a new mechanism underlying the negative inotropic responses of various cardiac preparations to protein kinase C-activating phorbol esters.
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Affiliation(s)
- T A Noland
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
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