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Le NT. The significance of ERK5 catalytic-independent functions in disease pathways. Front Cell Dev Biol 2023; 11:1235217. [PMID: 37601096 PMCID: PMC10436230 DOI: 10.3389/fcell.2023.1235217] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 07/26/2023] [Indexed: 08/22/2023] Open
Abstract
Extracellular signal-regulated kinase 5 (ERK5), also known as BMK1 or MAPK7, represents a recent addition to the classical mitogen-activated protein kinase (MAPK) family. This family includes well-known members such as ERK1/2, c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (p38 MAPK), as well as atypical MAPKs such as ERK3, ERK4, ERK7 (ERK8), and Nemo-like kinase (NLK). Comprehensive reviews available elsewhere provide detailed insights into ERK5, which interested readers can refer to for in-depth knowledge (Nithianandarajah-Jones et al., 2012; Monti et al., Cancers (Basel), 2022, 14). The primary aim of this review is to emphasize the essential characteristics of ERK5 and shed light on the intricate nature of its activation, with particular attention to the catalytic-independent functions in disease pathways.
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Affiliation(s)
- Nhat-Tu Le
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, United States
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2
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Gao C, Gong J, Cao N, Wang Y, Steinberg SF. Lipid-independent activation of a muscle-specific PKCα splicing variant. Am J Physiol Heart Circ Physiol 2022; 323:H825-H832. [PMID: 36112502 PMCID: PMC9550568 DOI: 10.1152/ajpheart.00304.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/16/2022] [Accepted: 08/28/2022] [Indexed: 11/22/2022]
Abstract
Protein kinase C-α (PKCα) plays a major role in a diverse range of cellular processes. Studies to date have defined the regulatory controls and function of PKCα entirely based upon the previously annotated ubiquitously expressed prototypical isoform. From RNA-seq-based transcriptome analysis in murine heart, we identified a previously unannotated PKCα variant produced by alternative RNA splicing. This PKCα transcript variant, which we named PKCα-novel exon (PKCα-NE), contains an extra exon between exon 16 and exon 17, and is specifically detected in adult mouse cardiac and skeletal muscle, but not other tissues; it is also detected in human hearts. This transcript variant yields a PKCα isoform with additional 16 amino acids inserted in its COOH-terminal variable region. Although the canonical PKCα enzyme is a lipid-dependent kinase, in vitro kinase assays show that PKCα-NE displays a high level of basal lipid-independent catalytic activity. Our unbiased proteomic analysis identified a specific interaction between PKCα-NE and eukaryotic elongation factor-1α (eEF1A1). Studies in cardiomyocytes link PKCα-NE expression to an increase in eEF1A1 phosphorylation and elevated protein synthesis. In summary, we have identified a previously uncharacterized muscle-specific PKCα splicing variant, PKCα-NE, with distinct biochemical properties that plays a unique role in the control of the protein synthesis machinery in cardiomyocytes.NEW & NOTEWORTHY PKCα is an important signaling molecule extensively studied in many cellular processes. However, no isoforms have been reported for PKCα except one prototypic isoform. Alternative mRNA splicing of Prkca gene was detected for the first time in rodent and human cardiac tissue, which can produce a previously unknown PKCα-novel exon (NE) isoform. The biochemistry and molecular effects of PKCα-NE are markedly different from PKCα wild type, suggesting potential functional diversity of PKCα signaling in muscle.
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Affiliation(s)
- Chen Gao
- Department of Pharmacology and System Physiology, University of Cincinnati, Cincinnati, Ohio
| | - Jianli Gong
- The Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, New York
| | - Nancy Cao
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Yibin Wang
- Signature Research Program in Cardiovascular and Metabolic Diseases, Duke-NUS Medical School, Singapore
| | - Susan F Steinberg
- The Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, New York
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3
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The Histone Modifications of Neuronal Plasticity. Neural Plast 2021; 2021:6690523. [PMID: 33628222 PMCID: PMC7892255 DOI: 10.1155/2021/6690523] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/21/2021] [Accepted: 01/30/2021] [Indexed: 12/19/2022] Open
Abstract
Nucleosomes composed of histone octamer and DNA are the basic structural unit in the eukaryote chromosome. Under the stimulation of various factors, histones will undergo posttranslational modifications such as methylation, phosphorylation, acetylation, and ubiquitination, which change the three-dimensional structure of chromosomes and affect gene expression. Therefore, the combination of different states of histone modifications modulates gene expression is called histone code. The formation of learning and memory is one of the most important mechanisms for animals to adapt to environmental changes. A large number of studies have shown that histone codes are involved in the formation and consolidation of learning and memory. Here, we review the most recent literature of histone modification in regulating neurogenesis, dendritic spine dynamic, synapse formation, and synaptic plasticity.
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4
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Stathopoulou K, Schobesberger S, Bork NI, Sprenger JU, Perera RK, Sotoud H, Geertz B, David JP, Christ T, Nikolaev VO, Cuello F. Divergent off-target effects of RSK N-terminal and C-terminal kinase inhibitors in cardiac myocytes. Cell Signal 2019; 63:109362. [PMID: 31344438 DOI: 10.1016/j.cellsig.2019.109362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/18/2019] [Accepted: 07/18/2019] [Indexed: 12/15/2022]
Abstract
P90 ribosomal S6 kinases (RSK) are ubiquitously expressed and regulate responses to neurohumoral stimulation. To study the role of RSK signalling on cardiac myocyte function and protein phosphorylation, pharmacological RSK inhibitors were tested. Here, the ATP competitive N-terminal kinase domain-targeting compounds D1870 and SL0101 and the allosteric C-terminal kinase domain-targeting FMK were evaluated regarding their ability to modulate cardiac myocyte protein phosphorylation. Exposure to D1870 and SL0101 significantly enhanced phospholamban (PLN) Ser16 and cardiac troponin I (cTnI) Ser22/23 phosphorylation in response to D1870 and SL0101 upon exposure to phenylephrine (PE) that activates RSK. In contrast, FMK pretreatment significantly reduced phosphorylation of both proteins in response to PE. D1870-mediated enhancement of PLN Ser16 phosphorylation was also observed after exposure to isoprenaline or noradrenaline (NA) stimuli that do not activate RSK. Inhibition of β-adrenoceptors by atenolol or cAMP-dependent protein kinase (PKA) by H89 prevented the D1870-mediated increase in PLN phosphorylation, suggesting that PKA is the kinase responsible for the observed phosphorylation. Assessment of changes in cAMP formation by FRET measurements revealed increased cAMP formation in vicinity to PLN after exposure to D1870 and SL0101. D1870 inhibited phosphodiesterase activity similarly as established PDE inhibitors rolipram or 3-isobutyl-1-methylxanthine. Assessment of catecholamine-mediated force development in rat ventricular muscle strips revealed significantly reduced EC50 for NA after D1870 pretreatment (DMSO/NA: 2.33 μmol/L vs. D1870/NA: 1.30 μmol/L). The data reveal enhanced cardiac protein phosphorylation by D1870 and SL0101 that was not detectable in response to FMK. This disparate effect might be attributed to off-target inhibition of PDEs with impact on muscle function as demonstrated for D1870.
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Affiliation(s)
- Konstantina Stathopoulou
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Sophie Schobesberger
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Nadja I Bork
- DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Julia U Sprenger
- DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Ruwan K Perera
- DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Hannieh Sotoud
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Birgit Geertz
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Jean-Pierre David
- Institute of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Viacheslav O Nikolaev
- DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Friederike Cuello
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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5
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Lin L, White SA, Hu K. Role of p90RSK in Kidney and Other Diseases. Int J Mol Sci 2019; 20:ijms20040972. [PMID: 30813401 PMCID: PMC6412535 DOI: 10.3390/ijms20040972] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/18/2019] [Accepted: 02/20/2019] [Indexed: 12/14/2022] Open
Abstract
The 90 kDa ribosomal s6 kinases (RSKs) are a group of serine/threonine kinases consisting of 4 RSK isoforms (RSK1-4), of which RSK1 is also designated as p90RSK. p90RSK plays an important role in the Ras-mitogen-activated protein kinase (MAPK) signalling cascade and is the direct downstream effector of Ras-extracellular signal-regulated kinase (ERK1/2) signalling. ERK1/2 activation directly phosphorylates and activates p90RSK, which, in turn, activates various signalling events through selection of different phosphorylation substrates. Upregulation of p90RSK has been reported in numerous human diseases. p90RSK plays an important role in the regulation of diverse cellular processes. Thus, aberrant activation of p90RSK plays a critical role in the pathogenesis of organ dysfunction and damage. In this review, we focus on the current understanding of p90RSK functions and roles in the development and progression of kidney diseases. Roles of p90RSK, as well as other RSKs, in cardiovascular disorders and cancers are also discussed.
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Affiliation(s)
- Ling Lin
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
| | - Samantha A White
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
| | - Kebin Hu
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
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Biesiadecki BJ, Westfall MV. Troponin I modulation of cardiac performance: Plasticity in the survival switch. Arch Biochem Biophys 2019; 664:9-14. [PMID: 30684464 DOI: 10.1016/j.abb.2019.01.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/11/2018] [Accepted: 01/22/2019] [Indexed: 01/21/2023]
Abstract
Signaling complexes targeting the myofilament are essential in modulating cardiac performance. A central target of this signaling is cardiac troponin I (cTnI) phosphorylation. This review focuses on cTnI phosphorylation as a model for myofilament signaling, discussing key gaps and future directions towards understanding complex myofilament modulation of cardiac performance. Human heart cTnI is phosphorylated at 14 sites, giving rise to a complex modulatory network of varied functional responses. For example, while classical Ser23/24 phosphorylation mediates accelerated relaxation, protein kinase C phosphorylation of cTnI serves as a brake on contractile function. Additionally, the functional response of cTnI multi-site phosphorylation cannot necessarily be predicted from the response of individual sites alone. These complexities underscore the need for systematically evaluating single and multi-site phosphorylation on myofilament cellular and in vivo contractile function. Ultimately, a complete understanding of these multi-site responses requires work to establish site occupancy and dominance, kinase/phosphatase signaling balance, and the function of adaptive secondary phosphorylation. As cTnI phosphorylation is essential for modulating cardiac performance, future insight into the complex role of cTnI phosphorylation is important to establish sarcomere signaling in the healthy heart as well as identification of novel myofilament targets in the treatment of disease.
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Affiliation(s)
- Brandon J Biesiadecki
- Department of Physiology and Cell Biology, The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, 43210, USA.
| | - Margaret V Westfall
- Department of Cardiac Surgery, University of Michigan, Ann Arbor, MI, 48109, USA.
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7
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Lee BK, Jung YS. Sustained Intracellular Acidosis Triggers the Na⁺/H⁺ Exchager-1 Activation in Glutamate Excitotoxicity. Biomol Ther (Seoul) 2017; 25:593-598. [PMID: 28605830 PMCID: PMC5685428 DOI: 10.4062/biomolther.2017.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 03/08/2017] [Accepted: 03/18/2017] [Indexed: 11/18/2022] Open
Abstract
The Na+/H+ exchanger-1 (NHE-1) is a ubiquitously expressed pH-regulatory membrane protein that functions in the brain, heart, and other organs. It is increased by intracellular acidosis through the interaction of intracellular H+ with an allosteric modifier site in the transport domain. In the previous study, we reported that glutamate-induced NHE-1 phosphorylation mediated by activation of protein kinase C-β (PKC-β) in cultured neuron cells via extracellular signal-regulated kinases (ERK)/p90 ribosomal s6 kinases (p90RSK) pathway results in NHE-1 activation. However, whether glutamate stimulates NHE-1 activity solely by the allosteric mechanism remains elusive. Cultured primary cortical neuronal cells were subjected to intracellular acidosis by exposure to 100 μM glutamate or 20 mM NH4Cl. After the desired duration of intracellular acidosis, the phosphorylation and activation of PKC-β, ERK1/2 and p90RSK were determined by Western blotting. We investigated whether the duration of intracellular acidosis is controlled by glutamate exposure time. The NHE-1 activation increased while intracellular acidosis sustained for >3 min. To determine if sustained intracellular acidosis induced NHE-1 phosphorylation, we examined phosphorylation of NHE-1 induced by intracellular acidosis by transient exposure to NH4Cl. Sustained intracellular acidosis led to activation and phosphorylation of NHE-1. In addition, sustained intracellular acidosis also activated the PKC-β, ERK1/2, and p90RSK in neuronal cells. We conclude that glutamate stimulates NHE-1 activity through sustained intracellular acidosis, which mediates NHE-1 phosphorylation regulated by PKC-β/ERK1/2/p90RSK pathway in neuronal cells.
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Affiliation(s)
- Bo Kyung Lee
- College of Pharmacy, Ajou University, Suwon 16499, Republic of Korea
| | - Yi-Sook Jung
- College of Pharmacy, Ajou University, Suwon 16499, Republic of Korea.,Research Institute of Pharmaceutical Sciences and Technology, Ajou University, Suwon 16499, Republic of Korea
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8
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Wen J, Huang C. Coxsackieviruses B3 infection of myocardial microvascular endothelial cells activates fractalkine via the ERK1/2 signaling pathway. Mol Med Rep 2017; 16:7548-7552. [PMID: 28944873 PMCID: PMC5865889 DOI: 10.3892/mmr.2017.7536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 09/07/2017] [Indexed: 12/13/2022] Open
Abstract
Infections by pathogens may lead to cardiovascular diseases, including acute/chronic myocarditis. (Coxsackieviruses B3) CVB3 is considered to be the most common causative agent in m‑yocarditis, which can lead to dilated cardiomyopathy. The present study aimed to investigate the mechanism of CVB3‑infected myocardial microvascular endothelial cells. The CVB3 infection was detected by 50% tissue culture infective dose (TCID50). The role of fractalkine (FKN) in the infection was detected using western blotting and RNA interference. To assess mitogen‑activated protein kinase signaling activity, levels of total and phosphorylated extracellular signal‑regulated kinase (ERK)1/2, c‑Jun N‑terminal kinase, and p38 were measured at 0, 20, 40, and 60 min after CVB3 infection by western blot analysis. The results showed that infection activated FKN via the ERK1/2 signaling pathway. Furthermore, the TCID50 of CVB3 in infected cells was lower compared with that in myocardial microvascular endothelial cells following ERK1/2 inhibition and FKN silencing. CVB3 infection of myocardial microvascular endothelial cells activates FKN via the ERK1/2 signaling pathway. These findings represent a foundation for the development of novel methods of treating CVB3‑induced myocarditis.
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Affiliation(s)
- Jili Wen
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
- Cardiovascular Research Institute, Wuhan University, Wuhan, Hubei 430060, P.R. China
- Hubei Key Laboratory of Cardiology, Wuhan, Hubei 430060, P.R. China
| | - Congxin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
- Cardiovascular Research Institute, Wuhan University, Wuhan, Hubei 430060, P.R. China
- Hubei Key Laboratory of Cardiology, Wuhan, Hubei 430060, P.R. China
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9
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Exposure to Amphetamines Leads to Development of Amphetamine Type Stimulants Associated Cardiomyopathy (ATSAC). Cardiovasc Toxicol 2017; 17:13-24. [PMID: 27663745 DOI: 10.1007/s12012-016-9385-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
With rapidly rising prevalence of exposure to Amphetamine Type Stimulants (ATS), novel insights into cardiotoxic effects of this substance are being presented in the literature and remarkably ATS Associated Cardiomyopathy (ATSAC) is emerging as a novel cardiovascular condition with its distinctive pathogenesis, risk factors, clinical features and prognosis. A comprehensive systematic review was performed to explore and analyze the current evidence on the association between ATS exposure and development of cardiomyopathy, biological mechanisms involved in pathogenesis of ATSAC, risk factors, clinical features and course of patients with ATSAC. Several animal studies, case reports, case series and case-control studies support the association between ATS exposure and ATSAC. Oxidative stress, accelerated apoptosis, increased p53 activity, cardiomyocyte necrosis, perfusion defects, fatty acid toxicity, altered gene expression, abnormal cardiac protein synthesis and function in addition to defects in intracellular calcium hemostasis present themselves as likely mechanisms of cardiotoxicity in ATSAC. Majority of patients with ATSAC were found to be male, young and presented late with severe dilated cardiomyopathy. Female ATS users predominantly develop Takotsubo type of ATSAC and in particular its atypical basal variant. Overall, cessation of ATS exposure seems to be associated with some degree of reversibility and recovery in ATSAC sufferers.
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10
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Ryba DM, Li J, Cowan CL, Russell B, Wolska BM, Solaro RJ. Long-Term Biased β-Arrestin Signaling Improves Cardiac Structure and Function in Dilated Cardiomyopathy. Circulation 2017; 135:1056-1070. [PMID: 28104714 DOI: 10.1161/circulationaha.116.024482] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 01/12/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND Biased agonism of the angiotensin II receptor is known to promote cardiac contractility. Our laboratory indicated that these effects may be attributable to changes at the level of the myofilaments. However, these signaling mechanisms remain unknown. Because a common finding in dilated cardiomyopathy is a reduction in the myofilament-Ca2+ response, we hypothesized that β-arrestin signaling would increase myofilament-Ca2+ responsiveness in a model of familial dilated cardiomyopathy and improve cardiac function and morphology. METHODS We treated a dilated cardiomyopathy-linked mouse model expressing a mutant tropomyosin (Tm-E54K) for 3 months with either TRV120067, a β-arrestin 2-biased ligand of the angiotensin II receptor, or losartan, an angiotensin II receptor blocker. At the end of the treatment protocol, we assessed cardiac function using echocardiography, the myofilament-Ca2+ response of detergent-extracted fiber bundles, and used proteomic approaches to understand changes in posttranslational modifications of proteins that may explain functional changes. We also assessed signaling pathways altered in vivo and by using isolated myocytes. RESULTS TRV120067- treated Tm-E54K mice showed improved cardiac structure and function, whereas losartan-treated mice had no improvement. Myofilaments of TRV120067-treated Tm-E54K mice had significantly improved myofilament-Ca2+ responsiveness, which was depressed in untreated Tm-E54K mice. We attributed these changes to increased MLC2v and MYPT1/2 phosphorylation seen only in TRV120067-treated mice. We found that the functional changes were attributable to an activation of ERK1/2-RSK3 signaling, mediated through β-arrestin, which may have a novel role in increasing MLC2v phosphorylation through a previously unrecognized interaction of β-arrestin localized to the sarcomere. CONCLUSIONS Long-term β-arrestin 2-biased agonism of the angiotensin II receptor may be a viable approach to the treatment of dilated cardiomyopathy by not only preventing maladaptive signaling, but also improving cardiac function by altering the myofilament-Ca2+ response via β-arrestin signaling pathways.
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Affiliation(s)
- David M Ryba
- From Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago (D.M.R., J.L., B.R., B.M.W., R.J.S.); Department of Medicine, Division of Cardiology, University of Illinois at Chicago (B.M.W.); and Trevena, Inc. King of Prussia, PA (B.M.W.)
| | - Jieli Li
- From Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago (D.M.R., J.L., B.R., B.M.W., R.J.S.); Department of Medicine, Division of Cardiology, University of Illinois at Chicago (B.M.W.); and Trevena, Inc. King of Prussia, PA (B.M.W.)
| | - Conrad L Cowan
- From Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago (D.M.R., J.L., B.R., B.M.W., R.J.S.); Department of Medicine, Division of Cardiology, University of Illinois at Chicago (B.M.W.); and Trevena, Inc. King of Prussia, PA (B.M.W.)
| | - Brenda Russell
- From Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago (D.M.R., J.L., B.R., B.M.W., R.J.S.); Department of Medicine, Division of Cardiology, University of Illinois at Chicago (B.M.W.); and Trevena, Inc. King of Prussia, PA (B.M.W.)
| | - Beata M Wolska
- From Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago (D.M.R., J.L., B.R., B.M.W., R.J.S.); Department of Medicine, Division of Cardiology, University of Illinois at Chicago (B.M.W.); and Trevena, Inc. King of Prussia, PA (B.M.W.)
| | - R John Solaro
- From Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago (D.M.R., J.L., B.R., B.M.W., R.J.S.); Department of Medicine, Division of Cardiology, University of Illinois at Chicago (B.M.W.); and Trevena, Inc. King of Prussia, PA (B.M.W.).
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11
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Liu C, Du Q, Zhang X, Tang Z, Ji H, Li Y. Clematichinenoside Serves as a Neuroprotective Agent Against Ischemic Stroke: The Synergistic Action of ERK1/2 and cPKC Pathways. Front Cell Neurosci 2016; 9:517. [PMID: 26793066 PMCID: PMC4709476 DOI: 10.3389/fncel.2015.00517] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 12/23/2015] [Indexed: 12/18/2022] Open
Abstract
There are numerous evidences suggesting that inhibition of apoptosis of neurons play a critical role in preventing the damage and even death of neurons after brain ischemia/reperfusion, which shows therapeutic potential for clinical treatment of brain injury induced by stroke. In this study, we aimed to investigate the neuroprotective effect of Clematichinenoside (AR) and its underlying mechanisms. MCAO mode was performed in rats and OGD/R model in primary cortical neurons to investigate the neuroprotective effect of AR. The rate of apoptotic cells was measured using TUNEL assay in cerebral cortex and flow cytometric assay in cortical neurons. Apoptosis-related proteins such as bcl-2, bcl-xl, and bax and the phosphorylation of ERK1/2, cPKC, p90RSK, and CREB in ischemic penumbra were assayed by western blot. Furthermore, we made a thorough inquiry about how these proteins play roles in the anti-apoptotic mechanism using targets-associated inhibitors step by step. The results revealed that AR could activate both ERK1/2 and cPKC which resulted in p90RSK phosphorylation and translocation into the nucleus. Moreover, CREB, a downstream target of p90RSK, was phosphorylated and then bound to cAMP-regulated enhancer (CRE) to activate apoptosis-related genes, and finally ameliorate ischemic stroke through preventing neuron death. In conclusion, these data strongly suggest that AR could be used as an effective neuroprotective agent to protect against ischemic stroke after cerebral I/R injury through regulating both ERK1/2 and cPKC mediated p90RSK/CREB apoptotic pathways.
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Affiliation(s)
- Chao Liu
- State Key Laboratory of Natural Medicines, Department of Physiology, China Pharmaceutical University Nanjing, China
| | - Qianming Du
- State Key Laboratory of Natural Medicines, Department of Pharmacology, China Pharmaceutical University Nanjing, China
| | - Xu Zhang
- Department of Combine Traditional Chinese and Western Medicine, College of Clinical Medicine, Chengdu University of TCM Chengdu, China
| | - Zhichao Tang
- State Key Laboratory of Natural Medicines, Department of Pharmacochemistry, China Pharmaceutical University Nanjing, China
| | - Hui Ji
- State Key Laboratory of Natural Medicines, Department of Pharmacology, China Pharmaceutical University Nanjing, China
| | - Yunman Li
- State Key Laboratory of Natural Medicines, Department of Physiology, China Pharmaceutical University Nanjing, China
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12
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Martinez EC, Passariello CL, Li J, Matheson CJ, Dodge-Kafka K, Reigan P, Kapiloff MS. RSK3: A regulator of pathological cardiac remodeling. IUBMB Life 2015; 67:331-7. [PMID: 25988524 PMCID: PMC4449288 DOI: 10.1002/iub.1383] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/08/2015] [Indexed: 12/18/2022]
Abstract
The family of p90 ribosomal S6 kinases (RSKs) are pleiotropic effectors for extracellular signal-regulated kinase signaling pathways. Recently, RSK3 was shown to be important for pathological remodeling of the heart. Although cardiac myocyte hypertrophy can be compensatory for increased wall stress, in chronic heart diseases, this nonmitotic cell growth is usually associated with interstitial fibrosis, increased cell death, and decreased cardiac function. Although RSK3 is less abundant in the cardiac myocyte than other RSK family members, RSK3 appears to serve a unique role in cardiac myocyte stress responses. A potential mechanism conferring the unique function of RSK3 in the heart is anchoring by the scaffold protein muscle A-kinase anchoring protein β (mAKAPβ). Recent findings suggest that RSK3 should be considered as a therapeutic target for the prevention of heart failure, a clinical syndrome of major public health significance.
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Affiliation(s)
- Eliana C. Martinez
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Catherine L. Passariello
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Jinliang Li
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Christopher J. Matheson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, USA
| | - Kimberly Dodge-Kafka
- Calhoun Center for Cardiology, University of Connecticut Health Center, Farmington, CT, USA
| | - Philip Reigan
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, USA
| | - Michael S. Kapiloff
- Department of Pediatrics, Division of Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL, USA
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13
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Na+/H+ exchanger isoform 1 induced cardiomyocyte hypertrophy involves activation of p90 ribosomal s6 kinase. PLoS One 2015; 10:e0122230. [PMID: 25830299 PMCID: PMC4382094 DOI: 10.1371/journal.pone.0122230] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 02/10/2015] [Indexed: 01/30/2023] Open
Abstract
Studies using pharmacological and genetic approaches have shown that increased activity/expression of the Na+/H+ exchanger isoform 1 (NHE1) play a critical role in the pathogenesis of cardiac hypertrophy. Despite the importance of NHE1 in cardiac hypertrophy, severe cerebrovascular side effects were associated with the use of NHE1 inhibitors when administered to patients with myocardial infarctions. p90 ribosomal S6 Kinase (RSK), a downstream regulator of the mitogen-activated protein kinase pathway, has also been implicated in cardiac hypertrophy. We hypothesized that RSK plays a role in the NHE1 induced cardiomyocyte hypertrophic response. Infection of H9c2 cardiomyoblasts with the active form of the NHE1 adenovirus induced hypertrophy and was associated with an increase in the phosphorylation of RSK (P<0.05). Parameters of hypertrophy such as cell area, protein content and atrial natriuretic mRNA expression were significantly reduced in H9c2 cardiomyoblasts infected with active NHE1 in the presence of dominant negative RSK (DN-RSK) (P<0.05). These results confirm that NHE1 lies upstream of RSK. Increased phosphorylation and activation of GATA4 at Ser261 was correlated with increased RSK phosphorylation. This increase was reversed upon inhibition of RSK or NHE1. These findings demonstrate for the first time that the NHE1 mediated hypertrophy is accounted for by increased activation and phosphorylation of RSK, which subsequently increased the phosphorylation of GATA4; eventually activating fetal gene transcriptional machinery.
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14
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Reactive oxygen species and excitation-contraction coupling in the context of cardiac pathology. J Mol Cell Cardiol 2014; 73:92-102. [PMID: 24631768 DOI: 10.1016/j.yjmcc.2014.03.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/05/2014] [Accepted: 03/01/2014] [Indexed: 01/12/2023]
Abstract
Reactive oxygen species (ROS) are highly reactive oxygen-derived chemical compounds that are by-products of aerobic cellular metabolism as well as crucial second messengers in numerous signaling pathways. In excitation-contraction-coupling (ECC), which links electrical signaling and coordinated cardiac contraction, ROS have a severe impact on several key ion handling proteins such as ion channels and transporters, but also on regulating proteins such as protein kinases (e.g. CaMKII, PKA or PKC), thereby pivotally influencing the delicate balance of this finely tuned system. While essential as second messengers, ROS may be deleterious when excessively produced due to a disturbed balance in Na(+) and Ca(2+) handling, resulting in Na(+) and Ca(2+) overload, SR Ca(2+) loss and contractile dysfunction. This may, in the end, result in systolic and diastolic dysfunction and arrhythmias. This review aims to provide an overview of the single targets of ROS in ECC and to outline the role of ROS in major cardiac pathologies, such as heart failure and arrhythmogenesis. This article is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System"
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15
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Lee BK, Yoon JS, Lee MG, Jung YS. Protein kinase C-β mediates neuronal activation of Na(+)/H(+) exchanger-1 during glutamate excitotoxicity. Cell Signal 2013; 26:697-704. [PMID: 24378530 DOI: 10.1016/j.cellsig.2013.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/05/2013] [Accepted: 12/22/2013] [Indexed: 11/25/2022]
Abstract
Na(+)/H(+) exchanger-1 (NHE-1) activity is known to play a critical role in the neuronal injury caused by glutamate. However, the underlying mechanism is not clear. This study shows that NHE-1 activation and its phosphorylation during glutamate exposure were attenuated by the inhibition of protein kinase C (PKC)-βI and -βII, leading to reduced neuronal death. In addition, activations of PKC-βI and -βII by PKC-βI and -βII CAT plasmid or by PMA, PKC-β pharmacological activator have stimulated the activity and phosphorylation of NHE-1, which were abolished by inhibition of PKC-β in neuronal cells. Furthermore, the inhibition of PKC-β has mediated neuroprotective effect on glutamate-induced cells, which is similar to neuroprotective efficacy of siRNA NHE-1 transfection. Taken together, these results suggest that activation of the PKC-βI and -βII pathway by glutamate increases the activity and phosphorylation of NHE-1, and that these increases contribute to neuronal cell death. In this study, we demonstrate that PKC-βI and -βII are involved in the regulation of NHE-1 activation following glutamate exposure in neuron.
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Affiliation(s)
- Bo Kyung Lee
- College of Pharmacy, Ajou University, 206, Worldcup-ro, Yeongtong-gu, Suwon 443-749, Republic of Korea.
| | - Jae Seok Yoon
- Department of Pharmacology, Yonsei University, College of Medicine, 50, Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea.
| | - Min Goo Lee
- Department of Pharmacology, Yonsei University, College of Medicine, 50, Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea.
| | - Yi-Sook Jung
- College of Pharmacy, Ajou University, 206, Worldcup-ro, Yeongtong-gu, Suwon 443-749, Republic of Korea; Research Institute of Pharmaceutical Sciences and Technology, Ajou University, 206, Worldcup-ro, Yeongtong-gu, Suwon 443-749, Republic of Korea.
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16
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Oikawa M, Wu M, Lim S, Knight WE, Miller CL, Cai Y, Lu Y, Blaxall BC, Takeishi Y, Abe JI, Yan C. Cyclic nucleotide phosphodiesterase 3A1 protects the heart against ischemia-reperfusion injury. J Mol Cell Cardiol 2013; 64:11-9. [PMID: 23988739 PMCID: PMC3869570 DOI: 10.1016/j.yjmcc.2013.08.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 08/08/2013] [Accepted: 08/13/2013] [Indexed: 10/26/2022]
Abstract
Phosphodiesterase 3A (PDE3A) is a major regulator of cAMP in cardiomyocytes. PDE3 inhibitors are used for acute treatment of congestive heart failure, but are associated with increased incidence of arrhythmias and sudden death with long-term use. We previously reported that chronic PDE3A downregulation or inhibition induced myocyte apoptosis in vitro. However, the cardiac protective effect of PDE3A has not been demonstrated in vivo in disease models. In this study, we examined the role of PDE3A in regulating myocardial function and survival in vivo using genetically engineered transgenic mice with myocardial overexpression of the PDE3A1 isozyme (TG). TG mice have reduced cardiac function characterized by reduced heart rate and ejection fraction (52.5±7.8% vs. 83.9±4.7%) as well as compensatory expansion of left ventricular diameter (4.19±0.19mm vs. 3.10±0.18mm). However, there was no maladaptive increase of fibrosis and apoptosis in TG hearts compared to wild type (WT) hearts, and the survival rates also remained the same. The diminution of cardiac contractile function is very likely attributed to a decrease in beta-adrenergic receptor (β-AR) response in TG mice. Importantly, the myocardial infarct size (4.0±1.8% vs. 24.6±3.8%) and apoptotic cell number (1.3±1.0% vs. 5.6±1.5%) induced by ischemia/reperfusion (I/R) injury were significantly attenuated in TG mice. This was associated with decreased expression of inducible cAMP early repressor (ICER) and increased expression of anti-apoptotic protein BCL-2. To further verify the anti-apoptotic effects of PDE3A1, we performed in vitro apoptosis study in isolated adult TG and WT cardiomyocytes. We found that the apoptotic rates stimulated by hypoxia/reoxygenation or H2O2 were indeed significantly reduced in TG myocytes, and the differences between TG and WT myocytes were completely reversed in the presence of the PDE3 inhibitor milrinone. These together indicate that PDE3A1 negatively regulates β-AR signaling and protects against I/R injury by inhibiting cardiomyocyte apoptosis.
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Affiliation(s)
- Masayoshi Oikawa
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Meiping Wu
- Department of Cardiovascular, Shanghai Hospital of TCM, Affiliated to Shanghai University of TCM, Shanghai, China
| | - Soyeon Lim
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Walter E. Knight
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Clint L. Miller
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Yujun Cai
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Yan Lu
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Burns C. Blaxall
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Yasuchika Takeishi
- Fukushima Medical University, Department of Cardiology and Hematology, Fukushima city, Fukushima prefecture, Japan
| | - Jun-ichi Abe
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
| | - Chen Yan
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, NY, USA
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17
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Loirand G, Sauzeau V, Pacaud P. Small G Proteins in the Cardiovascular System: Physiological and Pathological Aspects. Physiol Rev 2013; 93:1659-720. [DOI: 10.1152/physrev.00021.2012] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Small G proteins exist in eukaryotes from yeast to human and constitute the Ras superfamily comprising more than 100 members. This superfamily is structurally classified into five families: the Ras, Rho, Rab, Arf, and Ran families that control a wide variety of cell and biological functions through highly coordinated regulation processes. Increasing evidence has accumulated to identify small G proteins and their regulators as key players of the cardiovascular physiology that control a large panel of cardiac (heart rhythm, contraction, hypertrophy) and vascular functions (angiogenesis, vascular permeability, vasoconstriction). Indeed, basal Ras protein activity is required for homeostatic functions in physiological conditions, but sustained overactivation of Ras proteins or spatiotemporal dysregulation of Ras signaling pathways has pathological consequences in the cardiovascular system. The primary object of this review is to provide a comprehensive overview of the current progress in our understanding of the role of small G proteins and their regulators in cardiovascular physiology and pathologies.
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Affiliation(s)
- Gervaise Loirand
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
| | - Vincent Sauzeau
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
| | - Pierre Pacaud
- INSERM, UMR S1087; University of Nantes; and CHU Nantes, l'Institut du Thorax, Nantes, France
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18
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Abstract
High glucose inhibits mitochondrial respiration, known as the 'Crabtree effect', in cancer cells and possibly other cell types. The upstream pathways regulating this phenomenon are poorly understood. In diabetes, where glucose levels are elevated, the p90(RSK) (p90 ribosomal S6 kinase) has received much attention as a potential upstream mediator of the effects of high glucose. Evidence is also emerging that p90(RSK) may play a role in cancer cell signalling, although the role of p90(RSK) in regulating cancer cell metabolism is unclear. In the present paper, we provide an overview of the Crabtree effect and its relationship to mitochondrial metabolism. Furthermore, preliminary data are presented suggesting a role for p90(RSK) and its upstream components, the ERK (extracellular-signal-regulated kinase) family of MAPKs (mitogen-activated protein kinases), in the Crabtree effect.
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19
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Abstract
Oxidative stress accompanies a wide spectrum of clinically important cardiac disorders, including ischemia/reperfusion, diabetes mellitus, and hypertensive heart disease. Although reactive oxygen species (ROS) can activate signaling pathways that contribute to ischemic preconditioning and cardioprotection, high levels of ROS induce structural modifications of the sarcomere that impact on pump function and the pathogenesis of heart failure. However, the precise nature of the redox-dependent change in contractility is determined by the source/identity of the oxidant species, the level of oxidative stress, and the chemistry/position of oxidant-induced posttranslational modifications on individual proteins within the sarcomere. This review focuses on various ROS-induced posttranslational modifications of myofilament proteins (including direct oxidative modifications of myofilament proteins, myofilament protein phosphorylation by ROS-activated signaling enzymes, and myofilament protein cleavage by ROS-activated proteases) that have been implicated in the control of cardiac contractility.
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Affiliation(s)
- Susan F Steinberg
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, 630 W. 168 St, New York, NY 10032, USA.
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20
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Le NT, Heo KS, Takei Y, Lee H, Woo CH, Chang E, McClain C, Hurley C, Wang X, Li F, Xu H, Morrell C, Sullivan MA, Cohen MS, Serafimova IM, Taunton J, Fujiwara K, Abe JI. A crucial role for p90RSK-mediated reduction of ERK5 transcriptional activity in endothelial dysfunction and atherosclerosis. Circulation 2012; 127:486-99. [PMID: 23243209 DOI: 10.1161/circulationaha.112.116988] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Diabetes mellitus is a major risk factor for cardiovascular mortality by increasing endothelial cell (EC) dysfunction and subsequently accelerating atherosclerosis. Extracellular-signal regulated kinase 5 (ERK5) is activated by steady laminar flow and regulates EC function by increasing endothelial nitric oxide synthase expression and inhibiting EC inflammation. However, the role and regulatory mechanisms of ERK5 in EC dysfunction and atherosclerosis are poorly understood. Here, we report the critical role of the p90 ribosomal S6 kinase (p90RSK)/ERK5 complex in EC dysfunction in diabetes mellitus and atherosclerosis. METHODS AND RESULTS Inducible EC-specific ERK5 knockout (ERK5-EKO) mice showed increased leukocyte rolling and impaired vessel reactivity. To examine the role of endothelial ERK5 in atherosclerosis, we used inducible ERK5-EKO-LDLR(-/-) mice and observed increased plaque formation. When activated, p90RSK associated with ERK5, and this association inhibited ERK5 transcriptional activity and upregulated vascular cell adhesion molecule 1 expression. In addition, p90RSK directly phosphorylated ERK5 S496 and reduced endothelial nitric oxide synthase expression. p90RSK activity was increased in diabetic mouse vessels, and fluoromethyl ketone-methoxyethylamine, a specific p90RSK inhibitor, ameliorated EC-leukocyte recruitment and diminished vascular reactivity in diabetic mice. Interestingly, in ERK5-EKO mice, increased leukocyte rolling and impaired vessel reactivity were resistant to the beneficial effects of fluoromethyl ketone-methoxyethylamine, suggesting a critical role for endothelial ERK5 in mediating the salutary effects of fluoromethyl ketone-methoxyethylamine on endothelial dysfunction. Fluoromethyl ketone-methoxyethylamine also inhibited atherosclerosis formation in ApoE(-/-) mice. CONCLUSIONS Our study highlights the importance of the p90RSK/ERK5 module as a critical mediator of EC dysfunction in diabetes mellitus and atherosclerosis formation, thus revealing a potential new target for therapeutic intervention.
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Affiliation(s)
- Nhat-Tu Le
- Program in Chemistry and Chemical Biology, Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
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21
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Le NT, Takei Y, Shishido T, Woo CH, Chang E, Heo KS, Lee H, Lu Y, Morrell C, Oikawa M, McClain C, Wang X, Tournier C, Molina CA, Taunton J, Yan C, Fujiwara K, Patterson C, Yang J, Abe JI. p90RSK targets the ERK5-CHIP ubiquitin E3 ligase activity in diabetic hearts and promotes cardiac apoptosis and dysfunction. Circ Res 2012; 110:536-50. [PMID: 22267842 PMCID: PMC3306797 DOI: 10.1161/circresaha.111.254730] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 01/12/2011] [Indexed: 12/15/2022]
Abstract
RATIONALE Cardiomyocyte apoptosis is one of the key events in the development and progression of heart failure, and a crucial role for ICER (inducible cAMP early repressor) in this process has been previously reported. ERK5 is known to inhibit cardiac apoptosis after myocardial infarction (MI), especially in hyperglycemic states, via association with CHIP ubiquitin (Ub) ligase and subsequent upregulation of CHIP ligase activity, which induces ICER ubiquitination and subsequent protein degradation. The regulatory mechanism governing ERK5/CHIP interaction is unknown. OBJECTIVE We previously demonstrated increased p90RSK activation in the diabetic heart. As a logical extension of this work, we now investigate whether p90RSK activation inhibits ERK5-mediated CHIP activation, and subsequently increases ICER levels and apoptosis. METHODS AND RESULTS p90RSK activation inhibits ERK5/CHIP association and CHIP Ub ligase activity. p90RSK and CHIP share a common binding site in the ERK5 C-terminal domain (aa571-807). Overexpression of either p90RSK or an ERK5 fragment (aa571-807) inhibits ERK5/CHIP association, suggesting that p90RSK and CHIP competes for ERK5 binding and that p90RSK activation is critical for inhibiting ERK5/CHIP interaction. We also identified ERK5-S496 as being directly phosphorylated by p90RSK and demonstrated that an ERK5-S496A mutant significantly impairs Angiotensin II-mediated inhibition of CHIP activity and subsequent increase in ICER levels. In vivo, either cardiac-specific depletion of ERK5 or overexpression of p90RSK inhibits CHIP activity and accelerates cardiac apoptosis after MI-a phenomenon fully reversible by activating ERK5. CONCLUSIONS These data suggest a role for p90RSK in inhibiting CHIP activity and promoting cardiac apoptosis through binding to and phosphorylation of ERK5-S496.
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MESH Headings
- Angiotensin II/metabolism
- Animals
- Animals, Newborn
- Apoptosis
- Binding Sites
- Binding, Competitive
- Cells, Cultured
- Cyclic AMP Response Element Modulator/metabolism
- Diabetes Mellitus, Experimental/enzymology
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Experimental/physiopathology
- Enzyme Activation
- MAP Kinase Kinase 5/genetics
- MAP Kinase Kinase 5/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Mitogen-Activated Protein Kinase 7/deficiency
- Mitogen-Activated Protein Kinase 7/genetics
- Mitogen-Activated Protein Kinase 7/metabolism
- Myocardial Infarction/enzymology
- Myocardial Infarction/pathology
- Myocardial Infarction/physiopathology
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/pathology
- Rats
- Rats, Sprague-Dawley
- Ribosomal Protein S6 Kinases, 90-kDa/genetics
- Ribosomal Protein S6 Kinases, 90-kDa/metabolism
- Signal Transduction
- Time Factors
- Transfection
- Ubiquitin-Protein Ligases/genetics
- Ubiquitin-Protein Ligases/metabolism
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Affiliation(s)
- Nhat-Tu Le
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Yuichiro Takei
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Tetsuro Shishido
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Chang-Hoon Woo
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Eugene Chang
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Kyung-Sun Heo
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Hakjoo Lee
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Yan Lu
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Craig Morrell
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Masayoshi Oikawa
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Carolyn McClain
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Xin Wang
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Cathy Tournier
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Carlos A. Molina
- Department of Biology and Molecular Biology, Montclair State University, Montclair, New Jersey
| | - Jack Taunton
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, Calfornia
| | - Chen Yan
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Keigi Fujiwara
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
| | - Cam Patterson
- Carolina Cardiovascular Biology Center, University of North Carolina, Chapel Hill, North Carolina
| | - Jay Yang
- Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
| | - Jun-ichi Abe
- Aab Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, New York
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22
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Li T, Liu Z, Hu X, Ma K, Zhou C. Involvement of ERK–RSK cascade in phenylephrine-induced phosphorylation of GATA4. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:582-92. [DOI: 10.1016/j.bbamcr.2011.12.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 10/24/2011] [Accepted: 12/20/2011] [Indexed: 11/29/2022]
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23
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Bardswell SC, Cuello F, Kentish JC, Avkiran M. cMyBP-C as a promiscuous substrate: phosphorylation by non-PKA kinases and its potential significance. J Muscle Res Cell Motil 2011; 33:53-60. [PMID: 22089698 DOI: 10.1007/s10974-011-9276-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 11/04/2011] [Indexed: 11/26/2022]
Abstract
It is now generally accepted that phosphorylation of cMyBP-C is critically important in maintaining normal cardiac function. Although much of the work to date on phospho-regulation of cMyBP-C has focused on the role of protein kinase A (PKA, also known as cAMP-dependent protein kinase), recent evidence suggests that a number of non-PKA serine/threonine kinases, such as Ca(2+)/calmodulin-dependent protein kinase II, protein kinase C, protein kinase D and the 90-kDa ribosomal S6 kinase are also capable of targeting this key regulatory sarcomeric protein. This article reviews such evidence and proposes a hypothetical role for some of the pertinent signalling pathways in phospho-regulation of cMyBP-C in the setting of heart failure.
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Affiliation(s)
- Sonya C Bardswell
- Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, UK
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24
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Ferreira JCB, Koyanagi T, Palaniyandi SS, Fajardo G, Churchill EN, Budas G, Disatnik MH, Bernstein D, Brum PC, Mochly-Rosen D. Pharmacological inhibition of βIIPKC is cardioprotective in late-stage hypertrophy. J Mol Cell Cardiol 2011; 51:980-7. [PMID: 21920368 DOI: 10.1016/j.yjmcc.2011.08.025] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Revised: 08/04/2011] [Accepted: 08/25/2011] [Indexed: 11/16/2022]
Abstract
We previously found that in the hearts of hypertensive Dahl salt-sensitive rats, βIIPKC levels increase during the transition from compensated cardiac hypertrophy to cardiac dysfunction. Here we showed that a six-week treatment of these hypertensive rats with a βIIPKC-specific inhibitor, βIIV5-3, prolonged their survival by at least 6weeks, suppressed myocardial fibrosis and inflammation, and delayed the transition from compensated hypertrophy to cardiac dysfunction. In addition, changes in the levels of the Ca(2+)-handling proteins, SERCA2 and the Na(+)/Ca(2+) exchanger, as well as troponin I phosphorylation, seen in the control-treated hypertensive rats were not observed in the βΙΙPKC-treated rats, suggesting that βΙΙPKC contributes to the regulation of calcium levels in the myocardium. In contrast, treatment with the selective inhibitor of βIPKC, an alternative spliced form of βIIPKC, had no beneficial effects in these rats. We also found that βIIV5-3, but not βIV5-3, improved calcium handling in isolated rat cardiomyocytes and enhanced contractility in isolated rat hearts. In conclusion, our data using an in vivo model of cardiac dysfunction (late-phase hypertrophy), suggest that βIIPKC contributes to the pathology associated with heart failure and thus an inhibitor of βIIPKC may be a potential treatment for this disease.
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Affiliation(s)
- Julio C B Ferreira
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
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25
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Lipp P, Reither G. Protein kinase C: the "masters" of calcium and lipid. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a004556. [PMID: 21628429 DOI: 10.1101/cshperspect.a004556] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The coordinated and physiological behavior of living cells in an organism critically depends on their ability to interact with surrounding cells and with the extracellular space. For this, cells have to interpret incoming stimuli, correctly process the signals, and produce meaningful responses. A major part of such signaling mechanisms is the translation of incoming stimuli into intracellularly understandable signals, usually represented by second messengers or second-messenger systems. Two key second messengers, namely the calcium ion and signaling lipids, albeit extremely different in nature, play an important and often synergistic role in such signaling cascades. In this report, we will shed some light on an entire family of protein kinases, the protein kinases C, that are perfectly designed to exactly decode these two second messengers in all of their properties and convey the signaling content to downstream processes within the cell.
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Affiliation(s)
- Peter Lipp
- Institute for Molecular Cell Biology, Medical Faculty, Saarland University, Homburg/Saar, Germany.
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Abstract
Oxidative stress is common in many clinically important cardiac disorders, including ischemia/reperfusion, diabetes, and hypertensive heart disease. Oxidative stress leads to derangements in pump function due to changes in the expression or function of proteins that regulate intracellular Ca(2+) homeostasis. There is growing evidence that the cardiodepressant actions of reactive oxygen species (ROS) also are attributable to ROS-dependent signaling events in the sarcomere. This minireview focuses on myofilament protein post-translational modifications induced by ROS or ROS-activated signaling enzymes that regulate cardiac contractility.
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Affiliation(s)
- Marius P Sumandea
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky 40536, USA.
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Kroczynska B, Joshi S, Eklund EA, Verma A, Kotenko SV, Fish EN, Platanias LC. Regulatory effects of ribosomal S6 kinase 1 (RSK1) in IFNλ signaling. J Biol Chem 2011; 286:1147-56. [PMID: 21075852 PMCID: PMC3020721 DOI: 10.1074/jbc.m110.183566] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 11/12/2010] [Indexed: 01/11/2023] Open
Abstract
Although the mechanisms of generation of signals that control transcriptional activation of Type III IFN (IFNλ)-regulated genes have been identified, very little is known about the mechanisms by which the IFNλ receptor generates signals for mRNA translation of IFNλ-activated genes. We provide evidence that IFNλ activates the p90 ribosomal protein S6 kinase 1 (RSK1) and its downstream effector, initiation factor eIF4B. Prior to its engagement by the IFNλ receptor, the non-active form of RSK1 is present in a complex with the translational repressor 4E-BP1 in IFNλ-sensitive cells. IFNλ-inducible phosphorylation/activation of RSK1 results in its dissociation from 4E-BP1 at the same time that 4E-BP1 dissociates from eIF4E to allow formation of eIF4F and initiation of cap-dependent translation. Our studies demonstrate that such IFNλ-dependent engagement of RSK1 is essential for up-regulation of p21(WAF1/CIP1) expression, suggesting a mechanism for generation of growth-inhibitory responses. Altogether, our data provide evidence for a critical role for the activated RSK1 in IFNλ signaling.
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Affiliation(s)
- Barbara Kroczynska
- From the Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School and Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60611
| | - Sonali Joshi
- From the Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School and Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60611
| | - Elizabeth A. Eklund
- From the Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School and Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60611
| | - Amit Verma
- the Division of Hematology-Oncology, the Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Sergei V. Kotenko
- the Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Eleanor N. Fish
- the Division of Cell and Molecular Biology, Toronto Research Institute, University Health Network and Department of Immunology, University of Toronto, Toronto M5G 2M1, Ontario, Canada, and
| | - Leonidas C. Platanias
- From the Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School and Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60611
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Cuello F, Bardswell SC, Haworth RS, Ehler E, Sadayappan S, Kentish JC, Avkiran M. Novel role for p90 ribosomal S6 kinase in the regulation of cardiac myofilament phosphorylation. J Biol Chem 2010; 286:5300-10. [PMID: 21148481 DOI: 10.1074/jbc.m110.202713] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In myocardium, the 90-kDa ribosomal S6 kinase (RSK) is activated by diverse stimuli and regulates the sarcolemmal Na(+)/H(+) exchanger through direct phosphorylation. Only limited information is available on other cardiac RSK substrates and functions. We evaluated cardiac myosin-binding protein C (cMyBP-C), a sarcomeric regulatory phosphoprotein, as a potential RSK substrate. In rat ventricular myocytes, RSK activation by endothelin 1 (ET1) increased cMyBP-C phosphorylation at Ser(282), which was inhibited by the selective RSK inhibitor D1870. Neither ET1 nor D1870 affected the phosphorylation status of Ser(273) or Ser(302), cMyBP-C residues additionally targeted by cAMP-dependent protein kinase (PKA). Complementary genetic gain- and loss-of-function experiments, through the adenoviral expression of wild-type or kinase-inactive RSK isoforms, confirmed RSK-mediated phosphorylation of cMyBP-C at Ser(282). Kinase assays utilizing as substrate wild-type or mutated (S273A, S282A, S302A) recombinant cMyBP-C fragments revealed direct and selective Ser(282) phosphorylation by RSK. Immunolabeling with a Ser(P)(282) antibody and confocal fluorescence microscopy showed RSK-mediated phosphorylation of cMyBP-C across the C-zones of sarcomeric A-bands. In chemically permeabilized mouse ventricular muscles, active RSK again induced selective Ser(282) phosphorylation in cMyBP-C, accompanied by significant reduction in Ca(2+) sensitivity of force development and significant acceleration of cross-bridge cycle kinetics, independently of troponin I phosphorylation at Ser(22)/Ser(23). The magnitudes of these RSK-induced changes were comparable with those induced by PKA, which phosphorylated cMyBP-C additionally at Ser(273) and Ser(302). We conclude that Ser(282) in cMyBP-C is a novel cardiac RSK substrate and its selective phosphorylation appears to regulate cardiac myofilament function.
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Affiliation(s)
- Friederike Cuello
- King's College London British Heart Foundation Centre, Cardiovascular Division, St Thomas' Hospital, London SE1 7EH, United Kingdom
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29
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MK2 SUMOylation regulates actin filament remodeling and subsequent migration in endothelial cells by inhibiting MK2 kinase and HSP27 phosphorylation. Blood 2010; 117:2527-37. [PMID: 21131586 DOI: 10.1182/blood-2010-08-302281] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Actin filament remodeling regulates several endothelial cell (EC) processes such as contraction, migration, adhesion, and shape determination. Mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2)-mediated phosphorylation of heat-shock protein 27 kDa (HSP27) promotes actin filament remodeling, but little is known about the regulation of this event in ECs. We found that tumor necrosis factor-α (TNF-α) SUMOylated MK2 at lysine (K)-339 affected EC actin filament organization and migration. Loss of the MK2 SUMOylation site (MK2-K339R) increased MK2 kinase activity and prolonged HSP27 phosphorylation, enhancing its effects on actin filament-dependent events. Both TNF-α-mediated EC elongation and steady laminar shear stress-mediated EC alignment were increased by MK2-K339R. Moreover, kinase-dead dominant-negative MK2 (DN-MK2) inhibited these effects. Cell migration is a dynamic process regulated by actin filament remodeling. Both wild-type MK2 (WT-MK2) and DN-MK2 significantly enhanced TNF-mediated inhibition of EC migration, and MK2-K339R further augmented this effect. Interestingly, the p160-Rho-associated coiled-coil kinase (ROCK) inhibitor Y-27632 reversed this effect by MK2-K339R, which strongly suggests that both excessive and insufficient levels of actin filament remodeling can block EC migration. Our study shows that MK2 SUMOylation is a new mechanism for regulating actin filament dynamics in ECs.
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Manhas N, Shi Y, Taunton J, Sun D. p90 activation contributes to cerebral ischemic damage via phosphorylation of Na+/H+ exchanger isoform 1. J Neurochem 2010; 114:1476-86. [PMID: 20557427 DOI: 10.1111/j.1471-4159.2010.06868.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Excessive activation of Na+/H+ exchanger isoform 1 (NHE-1) plays a role in cerebral ischemic injury. The current study investigated whether NHE-1 protein in ischemic brains is regulated by extracellular signal-regulated kinase (ERK)/90-kDa ribosomal S6 kinase (p90(RSK)) signaling pathways. A transient focal ischemia in mice was induced by a 60-min-occlusion of the middle cerebral artery followed by reperfusion for 3, 10, or 60 min (Rp). Expression of phosphorylated ERK 1/2 was significantly elevated in the ipsilateral hemispheres at 3-10 min Rp and reduced by 60 min Rp. An increase in phosphorylation of p90(RSK), a known NHE-1 kinase, was also detected at 3-10 min Rp, which was accompanied with a transient elevation of NHE-1 phosphorylation (p-NHE-1). Stimulation of p90(RSK) in ischemic neurons was downstream of ERK activation because inhibition of MEK1 (MAP kinase/ERK kinase) with its inhibitor U0126 blocked phosphorylation of p90(RSK). Moreover, direct inhibition of p90(RSK) by its selective inhibitor fluoromethyl ketone not only reduced p-NHE-1 expression but also ischemic infarct volume. Taken together, our study revealed that reperfusion triggers a transient stimulation of the ERK/p90(RSK) pathway. p90(RSK) activation contributes to cerebral ischemic damage in part via activation of NHE-1 protein.
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Affiliation(s)
- Namratta Manhas
- Department of Neurosurgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
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31
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Berzingi C, Chen F, Finkel MS. P38 MAP Kinase Inhibitor Prevents Diastolic Dysfunction in Rats Following HIV gp120 Injection In vivo. Cardiovasc Toxicol 2009; 9:142-50. [DOI: 10.1007/s12012-009-9047-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 07/15/2009] [Indexed: 01/15/2023]
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Raf-1: a novel cardiac troponin T kinase. J Muscle Res Cell Motil 2009; 30:67-72. [PMID: 19381846 DOI: 10.1007/s10974-009-9176-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 04/01/2009] [Indexed: 01/20/2023]
Abstract
Phosphorylation of cardiac troponin is a key mechanism involved in regulation of contractile function. In vitro kinase assays revealed that lysates prepared from resting cardiomyocytes contain cardiac troponin I (cTnI) and cTnT kinase activity. cTnI phosphorylation is inhibited by pharmacologic inhibitors of PKA, PKC, Rho kinase and PKC effectors such as RSK and PKD; these kinase inhibitors do not inhibit phosphorylation of cTnT. Rather, cTnT phosphorylation is decreased by the Raf inhibitor GW5074. In vitro kinase assays show that recombinant Raf phosphorylates cTnT, and that Raf-dependent cTnT phosphorylation is abrogated by a T206E substitution; Raf does not phosphorylate cTnI. These studies identify Raf-dependent cTnT-Thr(206) phosphorylation as a novel mechanism that would link growth factor-dependent signaling pathways to dynamic changes in cardiac contractile function.
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33
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Metabolites of MDMA induce oxidative stress and contractile dysfunction in adult rat left ventricular myocytes. Cardiovasc Toxicol 2009; 9:30-8. [PMID: 19333788 DOI: 10.1007/s12012-009-9034-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 03/18/2009] [Indexed: 10/20/2022]
Abstract
Repeated administration of 3,4-methylenedioxymethamphetamine (MDMA) (ecstasy) produces eccentric left ventricular (LV) dilation and diastolic dysfunction. While the mechanism(s) underlying this toxicity are unknown, oxidative stress plays an important role. MDMA is metabolized into redox cycling metabolites that produce superoxide. In this study, we demonstrated that metabolites of MDMA induce oxidative stress and contractile dysfunction in adult rat left ventricular myocytes. Metabolites of MDMA used in this study included alpha-methyl dopamine, N-methyl alpha-methyl dopamine and 2,5-bis(glutathion-S-yl)-alpha-MeDA. Dihydroethidium was used to detect drug-induced increases in reactive oxygen species (ROS) production in ventricular myocytes. Contractile function and changes in intracellular calcium transients were measured in paced (1 Hz), Fura-2 AM loaded, myocytes using the IonOptix system. Production of ROS in ventricular myocytes treated with MDMA was not different from control. In contrast, all three metabolites of MDMA exhibited time- and concentration-dependent increases in ROS that were prevented by N-acetyl-cysteine (NAC). The metabolites of MDMA, but not MDMA alone, significantly decreased contractility and impaired relaxation in myocytes stimulated at 1 Hz. These effects were prevented by NAC. Together, these data suggest that MDMA-induced oxidative stress in the left ventricle can be due, at least in part, to the metabolism of MDMA to redox active metabolites.
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34
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Interferon-dependent engagement of eukaryotic initiation factor 4B via S6 kinase (S6K)- and ribosomal protein S6K-mediated signals. Mol Cell Biol 2009; 29:2865-75. [PMID: 19289497 DOI: 10.1128/mcb.01537-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Although the roles of Jak-Stat pathways in type I and II interferon (IFN)-dependent transcriptional regulation are well established, the precise mechanisms of mRNA translation for IFN-sensitive genes remain to be defined. We examined the effects of IFNs on the phosphorylation/activation of eukaryotic translation initiation factor 4B (eIF4B). Our data show that eIF4B is phosphorylated on Ser422 during treatment of sensitive cells with alpha IFN (IFN-alpha) or IFN-gamma. Such phosphorylation is regulated, in a cell type-specific manner, by either the p70 S6 kinase (S6K) or the p90 ribosomal protein S6K (RSK) and results in enhanced interaction of the protein with eIF3A (p170/eIF3A) and increased associated ATPase activity. Our data also demonstrate that IFN-inducible eIF4B activity and IFN-stimulated gene 15 protein (ISG15) or IFN-gamma-inducible chemokine CXCL-10 protein expression are diminished in S6k1/S6k2 double-knockout mouse embryonic fibroblasts. In addition, IFN-alpha-inducible ISG15 protein expression is blocked by eIF4B or eIF3A knockdown, establishing a requirement for these proteins in mRNA translation/protein expression by IFNs. Importantly, the generation of IFN-dependent growth inhibitory effects on primitive leukemic progenitors is dependent on activation of the S6K/eIF4B or RSK/eIF4B pathway. Taken together, our findings establish critical roles for S6K and RSK in the induction of IFN-dependent biological effects and define a key regulatory role for eIF4B as a common mediator and integrator of IFN-generated signals from these kinases.
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35
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Davis J, Westfall MV, Townsend D, Blankinship M, Herron TJ, Guerrero-Serna G, Wang W, Devaney E, Metzger JM. Designing heart performance by gene transfer. Physiol Rev 2008; 88:1567-651. [PMID: 18923190 DOI: 10.1152/physrev.00039.2007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The birth of molecular cardiology can be traced to the development and implementation of high-fidelity genetic approaches for manipulating the heart. Recombinant viral vector-based technology offers a highly effective approach to genetically engineer cardiac muscle in vitro and in vivo. This review highlights discoveries made in cardiac muscle physiology through the use of targeted viral-mediated genetic modification. Here the history of cardiac gene transfer technology and the strengths and limitations of viral and nonviral vectors for gene delivery are reviewed. A comprehensive account is given of the application of gene transfer technology for studying key cardiac muscle targets including Ca(2+) handling, the sarcomere, the cytoskeleton, and signaling molecules and their posttranslational modifications. The primary objective of this review is to provide a thorough analysis of gene transfer studies for understanding cardiac physiology in health and disease. By comparing results obtained from gene transfer with those obtained from transgenesis and biophysical and biochemical methodologies, this review provides a global view of cardiac structure-function with an eye towards future areas of research. The data presented here serve as a basis for discovery of new therapeutic targets for remediation of acquired and inherited cardiac diseases.
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Affiliation(s)
- Jennifer Davis
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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36
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Sriraman V, Modi SR, Bodenburg Y, Denner LA, Urban RJ. Identification of ERK and JNK as signaling mediators on protein kinase C activation in cultured granulosa cells. Mol Cell Endocrinol 2008; 294:52-60. [PMID: 18694803 DOI: 10.1016/j.mce.2008.07.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 06/02/2008] [Accepted: 07/14/2008] [Indexed: 01/11/2023]
Abstract
PKC signaling is critical for follicular development and the induction of ovulatory genes including Pgr, Prkg2, and Cyp11a1 (SCC). We investigated PKC signaling mechanisms in the JC-410 porcine granulosa cell line stably expressing an SCC-luciferase reporter gene containing 2kb of the porcine SCC promoter. Addition of phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C, induced the promoter approximately 6-fold over the basal levels in 4h. This effect was predominantly mediated by the PKC beta and delta isoforms. PMA-mediated induction of the SCC promoter was sensitive to inhibition of ERK1/2 or JNK. Inhibition of p38 MAP kinase or Src tyrosine kinase did not alter the PMA-mediated inducibility of the promoter. SCC promoter induction in response to PMA treatment required basal EGF-receptor activity, but did not involve ectodomain shedding. Western blot analyses using phospho-specific antibodies showed that PMA treatment of JC-410 cells induced phosphorylation of MEK1/2, ERK1/2, and its downstream target p90 RSK at 15min. We also documented the rapid phosphorylation of JNK1/2 in response to PMA treatment. Phosphorylation of ERK and JNK was robust and sustained in contrast to activation of PKA and EGF-receptor signaling in these cells. Pretreatment of JC-410 granulosa cells with IGF-1 had a synergistic effect on PMA-mediated induction of the SCC promoter. We demonstrated the importance of PMA activation of ERK signaling and the synergism with IGF-1 by showing similar responses for Prkg2 expression in primary granulosa cells. In conclusion, our studies demonstrated PMA activation of ERK and JNK signaling which is relevant in the regulation of gene expression during follicular development, ovulation, and luteinization.
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Affiliation(s)
- Venkataraman Sriraman
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555-1060, USA.
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Bartholomeu JB, Vanzelli AS, Rolim NP, Ferreira JC, Bechara LR, Tanaka LY, Rosa KT, Alves MM, Medeiros A, Mattos KC, Coelho MA, Irigoyen MC, Krieger EM, Krieger JE, Negrão CE, Ramires PR, Guatimosim S, Brum PC. Intracellular mechanisms of specific β-adrenoceptor antagonists involved in improved cardiac function and survival in a genetic model of heart failure. J Mol Cell Cardiol 2008; 45:240-9. [DOI: 10.1016/j.yjmcc.2008.05.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 05/16/2008] [Accepted: 05/16/2008] [Indexed: 12/15/2022]
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38
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Lu Z, Abe JI, Taunton J, Lu Y, Shishido T, McClain C, Yan C, Xu SP, Spangenberg TM, Xu H. Reactive oxygen species-induced activation of p90 ribosomal S6 kinase prolongs cardiac repolarization through inhibiting outward K+ channel activity. Circ Res 2008; 103:269-78. [PMID: 18599872 DOI: 10.1161/circresaha.107.166678] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
p90 ribosomal S6 kinase (p90RSK) is activated in cardiomyopathies caused by conditions such as ischemia/reperfusion injury and diabetes mellitus in which prolongation of cardiac repolarization and frequent arrhythmias are common. Molecular mechanisms underlying the electric remodeling in cardiac diseases are largely unknown. In the present study, we determined the role of p90RSK activation in the modulation of voltage-gated K+ channel activity determining cardiac repolarization. Mice with increased cardiac p90RSK activity due to transgenic expression of p90RSK (p90RSK-Tg) had prolongation of QT intervals and of ventricular myocyte action potential durations. Fast transient outward K+ current (I(to,f)), slow delayed outward K+ current (I(K,slow)), and steady-state K+ current (I(SS)) were significantly decreased in p90RSK-Tg mouse ventricular myocytes. mRNA levels of Kv4.3, Kv4.2, Kv1.5, Kv2.1, and KChIP2 from ventricles between p90RSK-Tg and nontransgenic littermate control mice were similar, as assessed by quantitative reverse transcriptase-polymerase chain reaction, indicating that p90RSK regulates voltage-gated K+ channels through posttranslational modification. Kv4.3- and Kv1.5- rather than Kv4.2- and Kv2.1-encoded channels in HEK 293 cells were inhibited by p90RSK. In vitro phosphorylation analysis showed that Kv4.3 was phosphorylated by p90RSK at 2 conserved sites, Ser516 and Ser550. p90RSK expression significantly inhibited Kv4.3- and Kv4.3 and KChIP2-encoded channel activities in HEK 293 cells, whereas p90RSK's effects were blocked by amino acid mutation(s) at phosphorylation site(s) in Kv4.3. Hydrogen peroxide, a mediator of induced cardiac p90RSK activation in ischemia/reperfusion injury and diabetes mellitus, had effects similar to those of p90RSK on Kv4.3- or Kv4.3- and KChIP2-encoded channels. Fluoromethylketone, a specific p90RSK inhibitor, abolished hydrogen peroxide effects. These findings indicate that p90RSK activation is critical for reactive oxygen species-mediated inhibition of voltage-gated K+ channel activity and leads to prolongation of cardiac repolarization.
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Affiliation(s)
- Zhibo Lu
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
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Solaro RJ. Multiplex kinase signaling modifies cardiac function at the level of sarcomeric proteins. J Biol Chem 2008; 283:26829-33. [PMID: 18567577 DOI: 10.1074/jbc.r800037200] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- R John Solaro
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, University of Illinois, Chicago, Illinois 60612, USA.
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40
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Wu SC, Solaro RJ. Protein kinase C zeta. A novel regulator of both phosphorylation and de-phosphorylation of cardiac sarcomeric proteins. J Biol Chem 2007; 282:30691-8. [PMID: 17724026 PMCID: PMC2597085 DOI: 10.1074/jbc.m703670200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Our experiments investigated associations of specific isoforms of protein kinase C (PKC) with individual proteins in the cardiac troponin complex. Troponin I (cTnI) associated with PKCepsilon and zeta and troponin T (cTnT) associated with PKC alpha, delta, and epsilon. Based on its association with cTnI, we hypothesized that PKCzeta is a major regulator of myofilament protein phosphorylation. To test this, we infected adult cardiac myocytes with adenoviral constructs containing DsRed monomer-tagged wild type (WT) and the following constitutively active forms of PKCzeta: the pseudo-substrate region (A119E), 3'-phospho-inositide-dependent kinase-1 (T410E), and auto-phosphorylation (T560E). The A119E and T410E mutants displayed increased localization to the Z-discs compared with WT and T560E. Immunoprecipitations were performed in myocytes expressing PKCzeta using PKC phospho-motif antibodies to determine the phosphorylation of cTnI, cTnT, tropomyosin, myosin-binding protein C, and desmin. We did not find serine (Ser) phosphorylation of cTnI or cTnT. However, we observed a significant decrease in threonine (Thr) phosphorylation of cTnI and cTnT notably by PKCzeta T560E. Ser phosphorylation of tropomyosin was increased by all three active mutants of PKCzeta. Ser/Thr phosphorylation of myosin-binding protein C increased primarily by PKCzeta A119E. Both PKCzeta A119E and T410E mutants increased desmin Ser/Thr phosphorylation. To explain the apparent Thr dephosphorylation of cTnI and cTnT, we hypothesized that PKCzeta exists as a complex with p21-activated kinase-1 (Pak1) and protein phosphatase 2A (PP2A), and this was confirmed by immunoprecipitation Western blot. Our data demonstrate that PKCzeta is a novel regulator of myofilament protein phosphorylation.
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Affiliation(s)
| | - R. John Solaro
- To whom correspondence should be addressed: Dept. of Physiology and Biophysics (M/C 901), University of Illinois at Chicago College of Medicine, 835 South Wolcott Ave., Chicago, IL 60612-7342, Tel.: 312-996-7620; Fax: 312-996-1414; E-mail:
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Liu L, Li J, Liu J, Yuan Z, Pierre SV, Qu W, Zhao X, Xie Z. Involvement of Na+/K+-ATPase in hydrogen peroxide-induced hypertrophy in cardiac myocytes. Free Radic Biol Med 2006; 41:1548-56. [PMID: 17045923 DOI: 10.1016/j.freeradbiomed.2006.08.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 08/08/2006] [Accepted: 08/21/2006] [Indexed: 10/24/2022]
Abstract
We have shown that increased production of reactive oxygen species (ROS) was required for ouabain-induced hypertrophy in cultured cardiac myocytes. In the present study we assessed whether long-term exposure of myocytes to nontoxic ROS stress alone is sufficient to induce hypertrophy. A moderate amount of H2O2 was continuously generated in culture media by glucose oxidase. This resulted in a steady increase in intracellular ROS in cultured cardiac myocytes for at least 12 h. Such sustained, but not transient, increase in intracellular ROS at a level comparable to that induced by ouabain was sufficient to stimulate protein synthesis, increase cell size, and change the expression of several hypertrophic marker genes. Like ouabain, glucose oxidase increased intracellular Ca2+ and activated extracellular signal-regulated kinases 1 and 2 (ERK1/2). These effects of glucose oxidase were additive to ouabain-induced cellular changes. Furthermore, glucose oxidase stimulated endocytosis of the plasma membrane Na+/K+-ATPase, resulting in significant inhibition of sodium pump activity. While inhibition of ERK1/2 abolished glucose oxidase-induced increases in protein synthesis, chelating intracellular Ca2+ by BAPTA-AM showed no effect. These results, taken together with our prior observations, suggest that ROS may cross talk with Na+/K+-ATPase, leading to the activation of hypertrophic pathways in cardiac myocytes.
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Affiliation(s)
- Lijun Liu
- Department of Physiology, Pharmacology, Metabolism and Cardiovascular Sciences, Medical University of Ohio, Toledo, OH 43614, USA
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Deshmukh PA, Blunt BC, Hofmann PA. Acute modulation of PP2a and troponin I phosphorylation in ventricular myocytes: studies with a novel PP2a peptide inhibitor. Am J Physiol Heart Circ Physiol 2006; 292:H792-9. [PMID: 17012362 DOI: 10.1152/ajpheart.00225.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study demonstrates that acute activation with either beta-adrenergic receptor agonists or H(2)O(2) treatment increases protein phosphatase 2a (PP2a) activity in ventricular myocytes. PP2a activation occurs concomitant with an increase in methylation of PP2a, changes in localization of a PP2a targeting subunit PP2aB56alpha, and a decrease in phosphorylation of PP2a substrates, such as troponin I (TnI) and ERK in ventricular myocytes. Okadaic acid, a well-established pharmacological inhibitor of PP2a, and the peptide Thr-Pro-Asp-Tyr-Phe-Leu (TPDYFL) were used to block PP2a methylation, localization, and phosphorylations. TPDYFL is a highly conserved sequence of the PP2a catalytic subunit COOH-terminus. Specifically, both okadaic acid and the peptide increased beta-adrenergic-cAMP-dependent phosphorylation of TnI and blocked the beta-adrenergic-cAMP-dependent translocation of PP2aB56alpha. TPDYFL, but not a scrambled version of this sequence, blocked H(2)O(2)-induced changes in PP2a methylation and TnI dephosphorylation. Okadaic acid produces similar inhibition of H(2)O(2) effects. Thus we propose that the novel peptide TPDYFL acts as an inhibitor of PP2a activity and may be a useful tool to increase our understanding of how PP2a is regulated and the role of PP2a in a variety of physiological and pathological processes. In addition, the present study is consistent with acute beta-adrenergic receptor activation and H(2)O(2) exposure, simultaneously activating kinases and PP2a to work on common substrates, such as TnI. We hypothesize that dual activation of opposing enzymes provides for a tighter regulation of substrate phosphorylations in ventricular myocytes.
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Affiliation(s)
- Prajwal A Deshmukh
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA
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Pantano C, Reynaert NL, van der Vliet A, Janssen-Heininger YMW. Redox-sensitive kinases of the nuclear factor-kappaB signaling pathway. Antioxid Redox Signal 2006; 8:1791-806. [PMID: 16987032 DOI: 10.1089/ars.2006.8.1791] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
NF-kappaB is an inducible transcription factor that plays a role in the expression of over one hundred genes involved in immunity, inflammation, proliferation, and in defense against apoptosis. NF-kappaB has been known to be redox regulated for some time and is a direct target for oxidation that can affect its ability to bind to DNA. Reactive oxygen species (ROS) have been identified as second messengers in cells, and play a role in receptor signaling and posttranslation modification of signaling molecules. These posttranslation modifications include oxidations of critical cysteines to sulfenic acids or mixed disulfides, which can affect the activity of proteins. Many kinases involved in direct or indirect activation of NF-kappaB are affected by oxidants and therefore, have the potential to alter NF-kappaB activity. This review will provide a summary of the NF-kappaB family, their activation and regulation, followed by a summary of cytoplasmic and nuclear kinases in this pathway whose activity is affected by oxidants. Additionally, recent investigations have revealed that the JNK signaling pathway, which is known to be redox regulated, and pro-apoptotic, is inhibited by NF-kappaB signaling. The crosstalk of NF-kappaB with other signaling pathways is therefore critical for cellular fate, notably survival or cell death under oxidative conditions, and will also be reviewed.
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Affiliation(s)
- Cristen Pantano
- Department of Pathology, University of Vermont College of Medicine, Burlington, 05405, USA
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Itoh S, Ding B, Shishido T, Lerner-Marmarosh N, Wang N, Maekawa N, Berk BC, Takeishi Y, Yan C, Blaxall BC, Abe JI. Role of p90 ribosomal S6 kinase-mediated prorenin-converting enzyme in ischemic and diabetic myocardium. Circulation 2006; 113:1787-98. [PMID: 16585392 DOI: 10.1161/circulationaha.105.578278] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Epidemiological data strongly indicate that diabetes increases the incidence of heart failure. Although the benefit of angiotensin-converting enzyme inhibitor (ACE-I) treatment during and after myocardial infarction has been found to be greater in diabetics than nondiabetics and activation of the renin-angiotensin system (RAS) has been implicated, the molecular basis of these actions remains unclear. METHODS AND RESULTS We generated transgenic mice with cardiac-specific overexpression of wild-type p90 ribosomal S6 kinase (WT-p90RSK-Tg) and a dominant-negative form of p90RSK (DN-p90RSK-Tg). Recovery of cardiac function after ischemia/reperfusion in WT-p90RSK-Tg isolated mouse hearts was significantly impaired. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed specific induction of prorenin-converting enzyme (PRECE) in WT-p90RSK-Tg mice. mRNA induction of PRECE was confirmed with serial angiotensinogen protein reduction after perfusion in WT-p90RSK-Tg mice, suggesting an increase of angiotensinogen cleavage and subsequent RAS activation in WT-p90RSK-Tg mice. We investigated the role of the RAS in WT-p90RSK-Tg animals after ischemia/reperfusion with the use of an ACE-I (captopril) and an angiotensin II type 1 receptor blocker (olmesartan). We did not observe any effect of these inhibitors in non-Tg littermate controls, thus corroborating other reports in rodents. In contrast, both captopril and olmesartan significantly improved cardiac function and reduced infarct size in WT-p90RSK-Tg mice. At 8 months of age, WT-p90RSK-Tg mice developed cardiac dysfunction. p90RSK activity and PRECE mRNA were both increased by streptozotocin-induced hyperglycemia in non-Tg littermate controls, whereas DN-p90RSK-Tg animals exposed to streptozotocin did not have PRECE induction. CONCLUSIONS This study demonstrates the critical role of p90RSK in hyperglycemia-mediated myocardial PRECE induction, which may explain the augmentation of the RAS in diabetic hearts and provide an alternative therapeutic approach to treat diabetic cardiomyopathy.
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Affiliation(s)
- Seigo Itoh
- Cardiovascular Research Institute, University of Rochester, Rochester, NY, USA
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Mizutani T, Fukushi S, Saijo M, Kurane I, Morikawa S. Regulation of p90RSK phosphorylation by SARS-CoV infection in Vero E6 cells. FEBS Lett 2006; 580:1417-24. [PMID: 16458888 PMCID: PMC7094696 DOI: 10.1016/j.febslet.2006.01.066] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 01/10/2006] [Accepted: 01/17/2006] [Indexed: 01/21/2023]
Abstract
The 90 kDa ribosomal S6 kinases (p90RSKs) are a family of broadly expressed serine/threonine kinases with two kinase domains activated by extracellular signal‐regulated protein kinase in response to many growth factors. Our recent study demonstrated that severe acute respiratory syndrome (SARS)‐coronavirus (CoV) infection of monkey kidney Vero E6 cells induces phosphorylation and dephosphorylation of signaling pathways, resulting in apoptosis. In the present study, we investigated the phosphorylation status of p90RSK, which is a well‐known substrate of these signaling pathways, in SARS‐CoV‐infected cells. Vero E6 mainly expressed p90RSK1 and showed weak expression of p90RSK2. In the absence of viral infection, Ser221 in the N‐terminal kinase domain was phosphorylated constitutively, whereas both Thr573 in the C‐terminal kinase domain and Ser380 between the two kinase domains were not phosphorylated in confluent cells. Ser380, which has been reported to be involved in autophosphorylation by activation of the C‐terminal kinase domain, was phosphorylated in confluent SARS‐CoV‐infected cells, and this phosphorylation was inhibited by http://SB203580, which is an inhibitor of p38 mitogen‐activated protein kinases (MAPK). Phosphorylation of Thr573 was not upregulated in SARS‐CoV‐infected cells. Thus, in virus‐infected cells, phosphorylation of Thr573 was not necessary to induce phosphorylation of Ser380. On the other hand, Both Thr573 and Ser380 were phosphorylated by treatment with epidermal growth factor (EGF) in the absence of p38 MAPK activation. Ser220 was constitutively phosphorylated despite infection. These results indicated that phosphorylation status of p90RSK by SARS‐CoV infection is different from that by stimulation of EGF. This is the first detailed report regarding regulation of p90RSK phosphorylation by virus infection.
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Affiliation(s)
- Tetsuya Mizutani
- Special Pathogens Laboratory, Department of Virology 1, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan.
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Arteaga GM, Warren CM, Milutinovic S, Martin AF, Solaro RJ. Specific enhancement of sarcomeric response to Ca2+protects murine myocardium against ischemia-reperfusion dysfunction. Am J Physiol Heart Circ Physiol 2005; 289:H2183-92. [PMID: 16024565 DOI: 10.1152/ajpheart.00520.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Alteration in myofilament response to Ca2+is a major mechanism for depressed cardiac function after ischemia-reperfusion (I/R) dysfunction. We tested the hypothesis that hearts with increased myofilament response to Ca2+are less susceptible to I/R. In one approach, we studied transgenic (TG) mice with a constitutive increase in myofilament Ca2+sensitivity in which the adult form of cardiac troponin I (cTnI) is stoichiometrically replaced with the embryonic/neonatal isoform, slow skeletal TnI (ssTnI). We also studied mouse hearts with EMD-57033, which acts specifically to enhance myofilament response to Ca2+. We subjected isolated, perfused hearts to an I/R protocol consisting of 25 min of no-flow ischemia followed by 30 min of reperfusion. After I/R, developed pressure and rates of pressure change were significantly depressed and end-diastolic pressure was significantly elevated in nontransgenic (NTG) control hearts. These changes were significantly blunted in TG hearts and in NTG hearts perfused with EMD-57033 during reperfusion, with function returning to nearly baseline levels. Ca2+- and cross bridge-dependent activation, protein breakdown, and phosphorylation in detergent-extracted fiber bundles were also investigated. After I/R NTG fiber bundles exhibited a significant depression of cross bridge-dependent activation and Ca2+-activated tension and length dependence of activation that were not evident in TG preparations. Only NTG hearts demonstrated a significant increase in cTnI phosphorylation. Our results support the hypothesis that specific increases in myofilament Ca2+sensitivity are able to diminish the effect of I/R on cardiac function.
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Affiliation(s)
- Grace M Arteaga
- Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, IL 60612, USA.
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