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Subramanian H, Nikolaev VO. AKAP12 Overexpression Affects Cardiac Function via PDE8. Circ Res 2024; 134:1023-1025. [PMID: 38603476 DOI: 10.1161/circresaha.124.324475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Affiliation(s)
- Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (H.S., V.O.N.)
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Germany (H.S., V.O.N.)
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (H.S., V.O.N.)
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Germany (H.S., V.O.N.)
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2
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Feng HZ, Huang X, Jin JP. N-terminal truncated cardiac troponin I enhances Frank-Starling response by increasing myofilament sensitivity to resting tension. J Gen Physiol 2023; 155:e202012821. [PMID: 36880803 PMCID: PMC10005897 DOI: 10.1085/jgp.202012821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/09/2022] [Accepted: 12/29/2022] [Indexed: 03/08/2023] Open
Abstract
Cardiac troponin I (cTnI) of higher vertebrates has evolved with an N-terminal extension, of which deletion via restrictive proteolysis occurs as a compensatory adaptation in chronic heart failure to increase ventricular relaxation and stroke volume. Here, we demonstrate in a transgenic mouse model expressing solely N-terminal truncated cTnI (cTnI-ND) in the heart with deletion of the endogenous cTnI gene. Functional studies using ex vivo working hearts showed an extended Frank-Starling response to preload with reduced left ventricular end diastolic pressure. The enhanced Frank-Starling response effectively increases systolic ventricular pressure development and stroke volume. A novel finding is that cTnI-ND increases left ventricular relaxation velocity and stroke volume without increasing the end diastolic volume. Consistently, the optimal resting sarcomere length (SL) for maximum force development in cTnI-ND cardiac muscle was not different from wild-type (WT) control. Despite the removal of the protein kinase A (PKA) phosphorylation sites in cTnI, β-adrenergic stimulation remains effective on augmenting the enhanced Frank-Starling response of cTnI-ND hearts. Force-pCa relationship studies using skinned preparations found that while cTnI-ND cardiac muscle shows a resting SL-resting tension relationship similar to WT control, cTnI-ND significantly increases myofibril Ca2+ sensitivity to resting tension. The results demonstrate that restrictive N-terminal deletion of cTnI enhances Frank-Starling response by increasing myofilament sensitivity to resting tension rather than directly depending on SL. This novel function of cTnI regulation suggests a myofilament approach to utilizing Frank-Starling mechanism for the treatment of heart failure, especially diastolic failure where ventricular filling is limited.
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Affiliation(s)
- Han-Zhong Feng
- Department of Physiology and Biophysics, University of Illinois at Chicago School of Medicine, Chicago, IL, USA
| | - Xupei Huang
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Jian-Ping Jin
- Department of Physiology and Biophysics, University of Illinois at Chicago School of Medicine, Chicago, IL, USA
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3
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Subramanian H, Nikolaev VO. A-Kinase Anchoring Proteins in Cardiac Myocytes and Their Roles in Regulating Calcium Cycling. Cells 2023; 12:cells12030436. [PMID: 36766777 PMCID: PMC9913689 DOI: 10.3390/cells12030436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/22/2023] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
The rate of calcium cycling and calcium transient amplitude are critical determinants for the efficient contraction and relaxation of the heart. Calcium-handling proteins in the cardiac myocyte are altered in heart failure, and restoring the proper function of those proteins is an effective potential therapeutic strategy. The calcium-handling proteins or their regulators are phosphorylated by a cAMP-dependent kinase (PKA), and thereby their activity is regulated. A-Kinase Anchoring Proteins (AKAPs) play a seminal role in orchestrating PKA and cAMP regulators in calcium handling and contractile machinery. This cAMP/PKA orchestration is crucial for the increased force and rate of contraction and relaxation of the heart in response to fight-or-flight. Knockout models and the few available preclinical models proved that the efficient targeting of AKAPs offers potential therapies tailor-made for improving defective calcium cycling. In this review, we highlight important studies that identified AKAPs and their regulatory roles in cardiac myocyte calcium cycling in health and disease.
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Affiliation(s)
- Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck
- Correspondence: (H.S.); (V.O.N.); Tel.: +49(0)40-7410-57383 (V.O.N.)
| | - Viacheslav O. Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck
- Correspondence: (H.S.); (V.O.N.); Tel.: +49(0)40-7410-57383 (V.O.N.)
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4
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Tsikas D, Redfors B. Pilot Study on Acute Effects of Pharmacological Intraperitoneal L-Homoarginine on Homeostasis of Lysine and Other Amino Acids in a Rat Model of Isoprenaline-Induced Takotsubo Cardiomyopathy. Int J Mol Sci 2022; 23:ijms23094734. [PMID: 35563125 PMCID: PMC9103764 DOI: 10.3390/ijms23094734] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/20/2022] [Accepted: 04/21/2022] [Indexed: 02/04/2023] Open
Abstract
L-Arginine:glycine amidinotransferase (AGAT) catalyzes the formation of L-homoarginine (hArg) and L-ornithine (Orn) from L-arginine (Arg) and L-lysine (Lys): Arg + Lys ↔ hArg + Orn; equilibrium constant KhArg. AGAT also catalyzes the formation of guanidinoacetate (GAA) and Orn from Arg and glycine (Gly): Arg + Gly ↔ GAA + Orn; equilibrium constant KGAA. In humans, pharmacological hArg is metabolized to Lys. Low circulating and low excretory concentrations of hArg are associated with worse outcomes and mortality in the renal and cardiovascular systems. The metabolism and pharmacology of hArg have been little investigated. In the present study, we investigated the effects of pharmacological hArg (i.p., 0, 20, 220, 440 mg/kg at time point 0 min) on amino acids homeostasis in a rat model of isoprenaline-induced takotsubo cardiomyopathy (i.p., 50 mg/kg at time point 15 min). We measured by gas chromatography-mass spectrometry free and proteinic amino acids, as well as the polyamines putrescine and spermidine in the heart, lung, kidney, and liver of ten rats sacrificed at various time points (range, 0 to 126 min). hArg administration resulted in multiple changes in the tissue contents of several free and proteinic amino acids, as well as in the putrescine-spermidine molar ratio, an indicator of polyamines catabolism. Our results suggest that Lys and Arg are major metabolites of pharmacological hArg. Kidneys and heart seem to play a major metabolic role for hArg. Circulating Lys does not change over time, yet there is a considerable interchange of free Lys between organs, notably kidney and heart, during the presence of isoprenaline in the rats (time range, 15 to 90 min). Antidromic changes were observed for KhArg and KGAA, notably in the heart in this time window. Our study shows for the first time that free hArg and sarcosine (N-methylglycine) are positively associated with each other. The acute effects of high-dosed hArg administration and isoprenaline on various amino acids and on AGAT-catalyzed reaction in the heart, lung, kidney, and liver are detailed and discussed.
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Affiliation(s)
- Dimitrios Tsikas
- Institute of Toxicology, Core Unit Proteomics, Hannover Medical School, 30623 Hannover, Germany
- Correspondence:
| | - Björn Redfors
- Department of Cardiology, Sahlgrenska University Hospital, 413 45 Gothenburg, Sweden;
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5
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Rasmussen M, Feng HZ, Jin JP. Evolution of the N-Terminal Regulation of Cardiac Troponin I for Heart Function of Tetrapods: Lungfish Presents an Example of the Emergence of Novel Submolecular Structure to Lead the Capacity of Adaptation. J Mol Evol 2022; 90:30-43. [PMID: 34966949 PMCID: PMC10926322 DOI: 10.1007/s00239-021-10039-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/27/2021] [Indexed: 11/26/2022]
Abstract
Troponin-based Ca2+ regulation of striated muscle contraction emerged approximately 700 million years ago with largely conserved functions during evolution. Troponin I (TnI) is the inhibitory subunit of troponin and has evolved into three muscle type-specific isoforms in vertebrates. Cardiac TnI is specifically expressed in the adult heart and has a unique N-terminal extension implicating a specific value during natural selection. The N-terminal extension of cardiac TnI in higher vertebrates contains β-adrenergic-regulated protein kinase A (PKA) phosphorylation sites as a mechanism to enhance cardiac muscle relaxation and facilitate ventricular filling. Phylogenic studies showed that the N-terminal extension of cardiac TnI first emerged in the genomes of early tetrapods as well as primordial lobe-finned fishes such as the coelacanth whereas it is absent in ray-finned fish. This apparently rapid evolution of β-adrenergic regulation of cardiac function suggests a high selection value for the heart of vertebrate animals on land to work under higher metabolic demands. Sequencing and PKA phosphorylation data showed that lungfish cardiac TnI has evolved with an amphibian-like N-terminal extension with prototype PKA phosphorylation sites while its overall structure remained fish like. The data demonstrate that the submolecular structure of TnI may evolve ahead of the whole protein for cardiac muscle contractility to adapt to new environmental conditions. Understanding the evolution of the β-adrenergic regulation of TnI and cardiac adaptation to the increased energetic demands of life on land adds knowledge for the treatment of human heart diseases and failure.
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Affiliation(s)
- Monica Rasmussen
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Han-Zhong Feng
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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6
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Warren CM, Halas M, Feng HZ, Wolska BM, Jin JP, Solaro RJ. NH 2-Terminal Cleavage of Cardiac Troponin I Signals Adaptive Response to Cardiac Stressors. JOURNAL OF CELLULAR SIGNALING 2021; 2:162-171. [PMID: 34541579 PMCID: PMC8444995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/29/2022]
Abstract
Cardiac sarcomeres express a variant of troponin I (cTnI) that contains a unique N-terminal extension of ~30 amino acids with regulatory phosphorylation sites. The extension is important in the control of myofilament response to Ca2+, which contributes to the neuro-humoral regulation of the dynamics of cardiac contraction and relaxation. Hearts of various species including humans express a stress-induced truncated variant of cardiac troponin I (cTnI-ND) missing the first ~30 amino acids and functionally mimicking the phosphorylated state of cTnI. Studies have demonstrated that upregulation of cTnI-ND potentially represents a homeostatic mechanism as well as an adaptive response in pathophysiology including ischemia/reperfusion injury, beta adrenergic maladaptive activation, and aging. We present evidence showing that cTnI-ND can modify the trigger for hypertrophic cardiomyopathy (HCM) by reducing the Ca2+ sensitivity of myofilaments from hearts with an E180G mutation in α-tropomyosin. Induction of this truncation may represent a therapeutic approach to modifying Ca2+-responses in hearts with hypercontractility or heat failure with preserved ejection fraction.
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Affiliation(s)
- Chad M. Warren
- Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, USA
| | - Monika Halas
- Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, USA
| | - Han-Zhong Feng
- Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, USA
| | - Beata M. Wolska
- Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, USA,Division of Cardiology, Center for Cardiovascular Research, University of Illinois at Chicago, USA
| | - Jian-Ping Jin
- Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, USA
| | - R. John Solaro
- Department of Physiology & Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, USA,Correspondence should be addressed to R. John Solaro;
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7
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Scorziello A, Borzacchiello D, Sisalli MJ, Di Martino R, Morelli M, Feliciello A. Mitochondrial Homeostasis and Signaling in Parkinson's Disease. Front Aging Neurosci 2020; 12:100. [PMID: 32372945 PMCID: PMC7186467 DOI: 10.3389/fnagi.2020.00100] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/24/2020] [Indexed: 12/14/2022] Open
Abstract
The loss of dopaminergic (DA) neurons in the substantia nigra leads to a progressive, long-term decline of movement and other non-motor deficits. The symptoms of Parkinson's disease (PD) often appear later in the course of the disease, when most of the functional dopaminergic neurons have been lost. The late onset of the disease, the severity of the illness, and its impact on the global health system demand earlier diagnosis and better targeted therapy. PD etiology and pathogenesis are largely unknown. There are mutations in genes that have been linked to PD and, from these complex phenotypes, mitochondrial dysfunction emerged as central in the pathogenesis and evolution of PD. In fact, several PD-associated genes negatively impact on mitochondria physiology, supporting the notion that dysregulation of mitochondrial signaling and homeostasis is pathogenically relevant. Derangement of mitochondrial homeostatic controls can lead to oxidative stress and neuronal cell death. Restoring deranged signaling cascades to and from mitochondria in PD neurons may then represent a viable opportunity to reset energy metabolism and delay the death of dopaminergic neurons. Here, we will highlight the relevance of dysfunctional mitochondrial homeostasis and signaling in PD, the molecular mechanisms involved, and potential therapeutic approaches to restore mitochondrial activities in damaged neurons.
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Affiliation(s)
- Antonella Scorziello
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, University of Naples Federico II, Naples, Italy
| | - Domenica Borzacchiello
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - Maria Jose Sisalli
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, University of Naples Federico II, Naples, Italy
| | - Rossana Di Martino
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, University of Naples Federico II, Naples, Italy
| | - Micaela Morelli
- Department of Biomedical Sciences, Section of Neuropsychopharmacology, University of Cagliari, Cagliari, Italy
| | - Antonio Feliciello
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
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8
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Baarsma HA, Han B, Poppinga WJ, Driessen S, Elzinga CRS, Halayko AJ, Meurs H, Maarsingh H, Schmidt M. Disruption of AKAP-PKA Interaction Induces Hypercontractility With Concomitant Increase in Proliferation Markers in Human Airway Smooth Muscle. Front Cell Dev Biol 2020; 8:165. [PMID: 32328490 PMCID: PMC7160303 DOI: 10.3389/fcell.2020.00165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 02/28/2020] [Indexed: 01/11/2023] Open
Abstract
With the ability to switch between proliferative and contractile phenotype, airway smooth muscle (ASM) cells can contribute to the progression of airway diseases such as asthma and chronic obstructive pulmonary disease (COPD), in which airway obstruction is associated with ASM hypertrophy and hypercontractility. A-kinase anchoring proteins (AKAPs) have emerged as important regulatory molecules in various tissues, including ASM cells. AKAPs can anchor the regulatory subunits of protein kinase A (PKA), and guide cellular localization via various targeting domains. Here we investigated whether disruption of the AKAP-PKA interaction, by the cell permeable peptide stearated (st)-Ht31, alters human ASM proliferation and contractility. Treatment of human ASM with st-Ht31 enhanced the expression of protein markers associated with cell proliferation in both cultured cells and intact tissue, although this was not accompanied by an increase in cell viability or cell-cycle progression, suggesting that disruption of AKAP-PKA interaction on its own is not sufficient to drive ASM cell proliferation. Strikingly, st-Ht31 enhanced contractile force generation in human ASM tissue with concomitant upregulation of the contractile protein α-sm-actin. This upregulation of α-sm-actin was independent of mRNA stability, transcription or translation, but was dependent on proteasome function, as the proteasome inhibitor MG-132 prevented the st-Ht31 effect. Collectively, the AKAP-PKA interaction appears to regulate markers of the multi-functional capabilities of ASM, and this alter the physiological function, such as contractility, suggesting potential to contribute to the pathophysiology of airway diseases.
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Affiliation(s)
- Hoeke A Baarsma
- Department of Molecular Pharmacology, University of Groningen, Groningen, Netherlands.,Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Bing Han
- Department of Molecular Pharmacology, University of Groningen, Groningen, Netherlands.,Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Wilfred J Poppinga
- Department of Molecular Pharmacology, University of Groningen, Groningen, Netherlands.,Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Saskia Driessen
- Department of Molecular Pharmacology, University of Groningen, Groningen, Netherlands
| | - Carolina R S Elzinga
- Department of Molecular Pharmacology, University of Groningen, Groningen, Netherlands
| | - Andrew J Halayko
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB, Canada
| | - Herman Meurs
- Department of Molecular Pharmacology, University of Groningen, Groningen, Netherlands.,Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Harm Maarsingh
- Department of Pharmaceutical Sciences, Lloyd L. Gregory School of Pharmacy, Palm Beach Atlantic University, West Palm Beach, FL, United States
| | - Martina Schmidt
- Department of Molecular Pharmacology, University of Groningen, Groningen, Netherlands.,Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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Fan Q, Yin X, Rababa'h A, Diaz Diaz A, Wijaya CS, Singh S, Suryavanshi SV, Vo HH, Saeed M, Zhang Y, McConnell BK. Absence of gravin-mediated signaling inhibits development of high-fat diet-induced hyperlipidemia and atherosclerosis. Am J Physiol Heart Circ Physiol 2019; 317:H793-H810. [PMID: 31441691 DOI: 10.1152/ajpheart.00215.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Gravin, an A-kinase anchoring protein, is known to play a role in regulating key processes that lead to inflammation and atherosclerosis development, namely, cell migration, proliferation, and apoptosis. We investigated the role of gravin in the development of high-fat diet (HFD)-induced atherosclerosis and hyperlipidemia. Five-week-old male wild-type (WT) and gravin-t/t mice were fed a normal diet or an HFD for 16 wk. Gravin-t/t mice showed significantly lower liver-to-body-weight ratio, cholesterol, triglyceride, and very low-density lipoprotein levels in serum as compared with WT mice on HFD. Furthermore, there was less aortic plaque formation coupled with decreased lipid accumulation and liver damage, as the gravin-t/t mice had lower levels of serum alanine aminotransferase and aspartate aminotransferase. Additionally, gravin-t/t HFD-fed mice had decreased expression of liver 3-hydroxy-3-methyl-glutaryl-CoA reductase, an essential enzyme for cholesterol synthesis and lower fatty acid synthase expression. Gravin-t/t HFD-fed mice also exhibited inhibition of sterol regulatory element binding protein-2 (SREBP-2) expression, a liver transcription factor associated with the regulation of lipid transportation. In response to platelet-derived growth factor receptor treatment, gravin-t/t vascular smooth muscle cells exhibited lower intracellular calcium transients and decreased protein kinase A- and protein kinase C-dependent substrate phosphorylation, notably involving the Erk1/2 signaling pathway. Collectively, these results suggest the involvement of gravin-dependent regulation of lipid metabolism via the reduction of SREBP-2 expression. The absence of gravin-mediated signaling lowers blood pressure, reduces plaque formation in the aorta, and decreases lipid accumulation and damage in the liver of HFD mice. Through these processes, the absence of gravin-mediated signaling complex delays the HFD-induced hyperlipidemia and atherosclerosis.NEW & NOTEWORTHY The gravin scaffolding protein plays a key role in the multiple enzymatic pathways of lipid metabolism. We have shown for the first time the novel role of gravin in regulating the pathways related to the initiation and progression of atherosclerosis. Specifically, an absence of gravin-mediated signaling decreases the lipid levels (cholesterol, triglyceride, and VLDL) that are associated with sterol regulatory element binding protein-2 downregulation.
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Affiliation(s)
- Qiying Fan
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Xing Yin
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Abeer Rababa'h
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | - Andrea Diaz Diaz
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Cori S Wijaya
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Santosh V Suryavanshi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Henry Hiep Vo
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Moawiz Saeed
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Yang Zhang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
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10
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Baltzer S, Klussmann E. Small molecules for modulating the localisation of the water channel aquaporin-2-disease relevance and perspectives for targeting local cAMP signalling. Naunyn Schmiedebergs Arch Pharmacol 2019; 392:1049-1064. [PMID: 31300862 DOI: 10.1007/s00210-019-01686-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/26/2019] [Indexed: 12/23/2022]
Abstract
The tight spatial and temporal organisation of cyclic adenosine monophosphate (cAMP) signalling plays a key role in arginine-vasopressin (AVP)-mediated water reabsorption in renal collecting duct principal cells and in a plethora of other processes such as in the control of cardiac myocyte contractility. This review critically discusses in vitro- and cell-based screening strategies for the identification of small molecules that interfere with AVP/cAMP signalling in renal principal cells; it features phenotypic screening and approaches for targeting protein-protein interactions of A-kinase anchoring proteins (AKAPs), which organise local cAMP signalling hubs. The discovery of novel chemical entities for the modulation of local cAMP will not only provide tools for elucidating molecular mechanisms underlying cAMP signalling. Novel chemical entities can also serve as starting points for the development of novel drugs for the treatment of human diseases. Examples illustrate how screening for small molecules can pave the way to novel approaches for the treatment of certain forms of diabetes insipidus, a disease caused by defects in AVP-mediated water reabsorption.
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Affiliation(s)
- Sandrine Baltzer
- Max Delbrück Center for Molecular Medicine Berlin (MDC), Helmholtz Association, Robert-Rössle-Strasse 10, 13125, Berlin, Germany
| | - Enno Klussmann
- Max Delbrück Center for Molecular Medicine Berlin (MDC), Helmholtz Association, Robert-Rössle-Strasse 10, 13125, Berlin, Germany. .,DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany. .,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health and Vegetative Physiology, Berlin, Germany.
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11
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The role of compartmentalized signaling pathways in the control of mitochondrial activities in cancer cells. Biochim Biophys Acta Rev Cancer 2018; 1869:293-302. [PMID: 29673970 DOI: 10.1016/j.bbcan.2018.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/13/2018] [Accepted: 04/14/2018] [Indexed: 02/06/2023]
Abstract
Mitochondria are the powerhouse organelles present in all eukaryotic cells. They play a fundamental role in cell respiration, survival and metabolism. Stimulation of G-protein coupled receptors (GPCRs) by dedicated ligands and consequent activation of the cAMP·PKA pathway finely couple energy production and metabolism to cell growth and survival. Compartmentalization of PKA signaling at mitochondria by A-Kinase Anchor Proteins (AKAPs) ensures efficient transduction of signals generated at the cell membrane to the organelles, controlling important aspects of mitochondrial biology. Emerging evidence implicates mitochondria as essential bioenergetic elements of cancer cells that promote and support tumor growth and metastasis. In this context, mitochondria provide the building blocks for cellular organelles, cytoskeleton and membranes, and supply all the metabolic needs for the expansion and dissemination of actively replicating cancer cells. Functional interference with mitochondrial activity deeply impacts on cancer cell survival and proliferation. Therefore, mitochondria represent valuable targets of novel therapeutic approaches for the treatment of cancer patients. Understanding the biology of mitochondria, uncovering the molecular mechanisms regulating mitochondrial activity andmapping the relevant metabolic and signaling networks operating in cancer cells will undoubtly contribute to create a molecular platform to be used for the treatment of proliferative disorders. Here, we will highlight the emerging roles of signaling pathways acting downstream to GPCRs and their intersection with the ubiquitin proteasome system in the control of mitochondrial activity in different aspects of cancer cell biology.
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12
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Li Z, Singh S, Suryavanshi SV, Ding W, Shen X, Wijaya CS, Gao WD, McConnell BK. Force development and intracellular Ca 2+ in intact cardiac muscles from gravin mutant mice. Eur J Pharmacol 2017; 807:117-126. [PMID: 28428008 DOI: 10.1016/j.ejphar.2017.04.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 04/13/2017] [Accepted: 04/13/2017] [Indexed: 02/08/2023]
Abstract
Gravin (AKAP12) is an A-kinase-anchoring-protein that scaffolds protein kinase A (PKA), β2-adrenergic receptor (β2-AR), protein phosphatase 2B and protein kinase C. Gravin facilitates β2-AR-dependent signal transduction through PKA to modulate cardiac excitation-contraction coupling and its removal positively affects cardiac contraction. Trabeculae from the right ventricles of gravin mutant (gravin-t/t) mice were employed for force determination. Simultaneously, corresponding intracellular Ca2+ transient ([Ca2+]i) were measured. Twitch force (Tf)-interval relationship, [Ca2+]i-interval relationship, and the rate of decay of post-extrasysolic potentiation (Rf) were also obtained. Western blot analysis were performed to correlate sarcomeric protein expression with alterations in calcium cycling between the WT and gravin-t/t hearts. Gravin-t/t muscles had similar developed force compared to WT muscles despite having lower [Ca2+]i at any given external Ca2+ concentration ([Ca2+]o). The time to peak force and peak [Ca2+]i were slower and the time to 75% relaxation was significantly prolonged in gravin-t/t muscles. Both Tf-interval and [Ca2+]i-interval relations were depressed in gravin-t/t muscles. Rf, however, did not change. Furthermore, Western blot analysis revealed decreased ryanodine receptor (RyR2) phosphorylation in gravin-t/t hearts. Gravin-t/t cardiac muscle exhibits increased force development in responsiveness to Ca2+. The Ca2+ cycling across the SR appears to be unaltered in gravin-t/t muscle. Our study suggests that gravin is an important component of cardiac contraction regulation via increasing myofilament sensitivity to calcium. Further elucidation of the mechanism can provide insights to role of gravin if any in the pathophysiology of impaired contractility.
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Affiliation(s)
- Zhitao Li
- Department of Pathophysiology, Harbin Medical University, Heilongjiang, China
| | - Sonal Singh
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Santosh V Suryavanshi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Texas Medical Center, Houston, TX, USA
| | - Wengang Ding
- Department of Anesthesiology of 2nd Affiliated Hospital, Harbin Medical University, Heilongjiang, China
| | - Xiaoxu Shen
- Cardiology Department, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, China
| | - Cori S Wijaya
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Texas Medical Center, Houston, TX, USA
| | - Wei Dong Gao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, 1800 Orleans Street, Zaye Tower 6208, Baltimore, MD 21287, USA.
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Texas Medical Center, Houston, TX, USA.
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13
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Liu Y, Chen L, Diaz AD, Benham A, Xu X, Wijaya CS, Fa'ak F, Luo W, Soibam B, Azares A, Yu W, Lyu Q, Stewart MD, Gunaratne P, Cooney A, McConnell BK, Schwartz RJ. Mesp1 Marked Cardiac Progenitor Cells Repair Infarcted Mouse Hearts. Sci Rep 2016; 6:31457. [PMID: 27538477 PMCID: PMC4990963 DOI: 10.1038/srep31457] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 07/18/2016] [Indexed: 12/15/2022] Open
Abstract
Mesp1 directs multipotential cardiovascular cell fates, even though it's transiently induced prior to the appearance of the cardiac progenitor program. Tracing Mesp1-expressing cells and their progeny allows isolation and characterization of the earliest cardiovascular progenitor cells. Studying the biology of Mesp1-CPCs in cell culture and ischemic disease models is an important initial step toward using them for heart disease treatment. Because of Mesp1's transitory nature, Mesp1-CPC lineages were traced by following EYFP expression in murine Mesp1(Cre/+); Rosa26(EYFP/+) ES cells. We captured EYFP+ cells that strongly expressed cardiac mesoderm markers and cardiac transcription factors, but not pluripotent or nascent mesoderm markers. BMP2/4 treatment led to the expansion of EYFP+ cells, while Wnt3a and Activin were marginally effective. BMP2/4 exposure readily led EYFP+ cells to endothelial and smooth muscle cells, but inhibition of the canonical Wnt signaling was required to enter the cardiomyocyte fate. Injected mouse pre-contractile Mesp1-EYFP+ CPCs improved the survivability of injured mice and restored the functional performance of infarcted hearts for at least 3 months. Mesp1-EYFP+ cells are bona fide CPCs and they integrated well in infarcted hearts and emerged de novo into terminally differentiated cardiac myocytes, smooth muscle and vascular endothelial cells.
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Affiliation(s)
- Yu Liu
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Li Chen
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Andrea Diaz Diaz
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX 77204, USA
| | - Ashley Benham
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Xueping Xu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Cori S Wijaya
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX 77204, USA
| | - Faisal Fa'ak
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX 77204, USA
| | - Weijia Luo
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Benjamin Soibam
- Department of Computer Science and Engineering Technology, University of Houston-Downtown, Houston, 77002, USA
| | - Alon Azares
- Stem Cell Engineering, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX 77030, USA
| | - Wei Yu
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Qiongying Lyu
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - M David Stewart
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA.,Stem Cell Engineering, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX 77030, USA
| | - Preethi Gunaratne
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Austin Cooney
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, TX 77204, USA
| | - Robert J Schwartz
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA.,Stem Cell Engineering, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX 77030, USA
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14
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Najafi A, Sequeira V, Kuster DWD, van der Velden J. β-adrenergic receptor signalling and its functional consequences in the diseased heart. Eur J Clin Invest 2016; 46:362-74. [PMID: 26842371 DOI: 10.1111/eci.12598] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 01/30/2016] [Indexed: 12/28/2022]
Abstract
BACKGROUND To maintain the balance between the demand of the body and supply (cardiac output), cardiac performance is tightly regulated via the parasympathetic and sympathetic nervous systems. In heart failure, cardiac output (supply) is decreased due to pathologic remodelling of the heart. To meet the demands of the body, the sympathetic system is activated and catecholamines stimulate β-adrenergic receptors (β-ARs) to increase contractile performance and cardiac output. Although this is beneficial in the acute phase, chronic β-ARs stimulation initiates a cascade of alterations at the cellular level, resulting in a diminished contractile performance of the heart. MATERIALS AND METHODS This narrative review includes results from previously published systematic reviews and clinical and basic research publications obtained via PubMed up to May 2015. RESULTS We discuss the alterations that occur during sustained β-AR stimulation in diseased myocardium and emphasize the consequences of β-AR overstimulation for cardiac function. In addition, current treatment options as well as future therapeutic strategies to treat patients with heart failure to normalize consequences of β-AR overstimulation are discussed. CONCLUSIONS The heart is able to protect itself from chronic stimulation of the β-ARs via desensitization and reduced membrane availability of the β-ARs. However, ultimately this leads to an impaired downstream signalling and decreased protein kinase A (PKA)-mediated protein phosphorylation. β-blockers are widely used to prevent β-AR overstimulation and restore β-ARs in the failing hearts. However, novel and more specific therapeutic treatments are needed to improve treatment of HF in the future.
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Affiliation(s)
- Aref Najafi
- Department of Physiology, VU University Medical Center, Institute for Cardiovascular research (ICaR-VU), Amsterdam, the Netherlands.,ICIN-Netherlands Heart Institute, Utrecht, the Netherlands
| | - Vasco Sequeira
- Department of Physiology, VU University Medical Center, Institute for Cardiovascular research (ICaR-VU), Amsterdam, the Netherlands
| | - Diederik W D Kuster
- Department of Physiology, VU University Medical Center, Institute for Cardiovascular research (ICaR-VU), Amsterdam, the Netherlands
| | - Jolanda van der Velden
- Department of Physiology, VU University Medical Center, Institute for Cardiovascular research (ICaR-VU), Amsterdam, the Netherlands.,ICIN-Netherlands Heart Institute, Utrecht, the Netherlands
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15
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Diviani D, Reggi E, Arambasic M, Caso S, Maric D. Emerging roles of A-kinase anchoring proteins in cardiovascular pathophysiology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:1926-36. [PMID: 26643253 DOI: 10.1016/j.bbamcr.2015.11.024] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 01/08/2023]
Abstract
Heart and blood vessels ensure adequate perfusion of peripheral organs with blood and nutrients. Alteration of the homeostatic functions of the cardiovascular system can cause hypertension, atherosclerosis, and coronary artery disease leading to heart injury and failure. A-kinase anchoring proteins (AKAPs) constitute a family of scaffolding proteins that are crucially involved in modulating the function of the cardiovascular system both under physiological and pathological conditions. AKAPs assemble multifunctional signaling complexes that ensure correct targeting of the cAMP-dependent protein kinase (PKA) as well as other signaling enzymes to precise subcellular compartments. This allows local regulation of specific effector proteins that control the function of vascular and cardiac cells. This review will focus on recent advances illustrating the role of AKAPs in cardiovascular pathophysiology. The accent will be mainly placed on the molecular events linked to the control of vascular integrity and blood pressure as well as on the cardiac remodeling process associated with heart failure. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.
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Affiliation(s)
- Dario Diviani
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et de Médecine, Lausanne 1005, Switzerland.
| | - Erica Reggi
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et de Médecine, Lausanne 1005, Switzerland
| | - Miroslav Arambasic
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et de Médecine, Lausanne 1005, Switzerland
| | - Stefania Caso
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et de Médecine, Lausanne 1005, Switzerland
| | - Darko Maric
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et de Médecine, Lausanne 1005, Switzerland
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16
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Saengklub N, Limprasutr V, Sawangkoon S, Buranakarl C, Hamlin RL, Kijtawornrat A. Acute effects of intravenous dronedarone on electrocardiograms, hemodynamics and cardiac functions in anesthetized dogs. J Vet Med Sci 2015; 78:177-86. [PMID: 26346474 PMCID: PMC4785105 DOI: 10.1292/jvms.15-0413] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dronedarone is a class III antiarrhythmic that has been used for management of atrial fibrillation in humans, but limited information was found in dogs. The objective of this study was to determine the acute effects of escalating concentrations of dronedarone on electrocardiograms (ECG), hemodynamics and cardiac mechanics in healthy dogs. A total of 7 beagle dogs were anesthetized with isoflurane and instrumented to obtain lead II ECG, pressures at ascending aorta, right atrium, pulmonary artery and left ventricle, and left ventricular pressure-volume relationship. Five dogs were given vehicle and followed by escalating doses of dronedarone (0.5, 1.0 and 2.5 mg/kg, 15 min for each dose), and two dogs were used as a vehicle-treated control. All parameters were measured at 15 min after the end of each dose. The results showed that all parameters in vehicle-treated dogs were unaltered. Dronedarone at 2.5 mg/kg significantly lengthened PQ interval (P<0.01), reduced cardiac output (P<0.01) and increased systemic vascular resistance (P<0.01). Dronedarone produced negative inotropy assessed by significantly lowered end-systolic pressure-volume relationship, preload recruitable stroke work, contractility index and dP/dtmax. It also impaired diastolic function by significantly increased end-diastolic pressure-volume relationship, tau and dP/dtmin. These results suggested that acute effects of dronedarone produced negative dromotropy, inotropy and lusitropy in anesthetized dogs. Care should be taken when given dronedarone to dogs, especially when the patients have impaired cardiac function.
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Affiliation(s)
- Nakkawee Saengklub
- Graduate Student in the Program of Animal Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
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17
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McConnell BK, Singh S, Fan Q, Hernandez A, Portillo JP, Reiser PJ, Tikunova SB. Knock-in mice harboring a Ca(2+) desensitizing mutation in cardiac troponin C develop early onset dilated cardiomyopathy. Front Physiol 2015; 6:242. [PMID: 26379556 PMCID: PMC4550777 DOI: 10.3389/fphys.2015.00242] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/11/2015] [Indexed: 12/05/2022] Open
Abstract
The physiological consequences of aberrant Ca(2+) binding and exchange with cardiac myofilaments are not clearly understood. In order to examine the effect of decreasing Ca(2+) sensitivity of cTnC on cardiac function, we generated knock-in mice carrying a D73N mutation (not known to be associated with heart disease in human patients) in cTnC. The D73N mutation was engineered into the regulatory N-domain of cTnC in order to reduce Ca(2+) sensitivity of reconstituted thin filaments by increasing the rate of Ca(2+) dissociation. In addition, the D73N mutation drastically blunted the extent of Ca(2+) desensitization of reconstituted thin filaments induced by cTnI pseudo-phosphorylation. Compared to wild-type mice, heterozygous knock-in mice carrying the D73N mutation exhibited a substantially decreased Ca(2+) sensitivity of force development in skinned ventricular trabeculae. Kaplan-Meier survival analysis revealed that median survival time for knock-in mice was 12 weeks. Echocardiographic analysis revealed that knock-in mice exhibited increased left ventricular dimensions with thinner walls. Echocardiographic analysis also revealed that measures of systolic function, such as ejection fraction (EF) and fractional shortening (FS), were dramatically reduced in knock-in mice. In addition, knock-in mice displayed electrophysiological abnormalities, namely prolonged QRS and QT intervals. Furthermore, ventricular myocytes isolated from knock-in mice did not respond to β-adrenergic stimulation. Thus, knock-in mice developed pathological features similar to those observed in human patients with dilated cardiomyopathy (DCM). In conclusion, our results suggest that decreasing Ca(2+) sensitivity of the regulatory N-domain of cTnC is sufficient to trigger the development of DCM.
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Affiliation(s)
- Bradley K. McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Qiying Fan
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Adriana Hernandez
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Jesus P. Portillo
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Peter J. Reiser
- Division of Biosciences, College of Dentistry, The Ohio State UniversityColumbus, OH, USA
| | - Svetlana B. Tikunova
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
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18
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Wijnker PJM, Li Y, Zhang P, Foster DB, dos Remedios C, Van Eyk JE, Stienen GJM, Murphy AM, van der Velden J. A novel phosphorylation site, Serine 199, in the C-terminus of cardiac troponin I regulates calcium sensitivity and susceptibility to calpain-induced proteolysis. J Mol Cell Cardiol 2015; 82:93-103. [PMID: 25771144 DOI: 10.1016/j.yjmcc.2015.03.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 03/04/2015] [Accepted: 03/05/2015] [Indexed: 12/28/2022]
Abstract
Phosphorylation of cardiac troponin I (cTnI) by protein kinase C (PKC) is implicated in cardiac dysfunction. Recently, Serine 199 (Ser199) was identified as a target for PKC phosphorylation and increased Ser199 phosphorylation occurs in end-stage failing compared with non-failing human myocardium. The functional consequences of cTnI-Ser199 phosphorylation in the heart are unknown. Therefore, we investigated the impact of phosphorylation of cTnI-Ser199 on myofilament function in human cardiac tissue and the susceptibility of cTnI to proteolysis. cTnI-Ser199 was replaced by aspartic acid (199D) or alanine (199A) to mimic phosphorylation and dephosphorylation, respectively, with recombinant wild-type (Wt) cTn as a negative control. Force development was measured at various [Ca(2+)] and at sarcomere lengths of 1.8 and 2.2 μm in demembranated cardiomyocytes in which endogenous cTn complex was exchanged with the recombinant human cTn complexes. In idiopathic dilated cardiomyopathy samples, myofilament Ca(2+)-sensitivity (pCa50) at 2.2 μm was significantly higher in 199D (pCa50 = 5.79 ± 0.01) compared to 199A (pCa50 = 5.65 ± 0.01) and Wt (pCa50 = 5.66 ± 0.02) at ~63% cTn exchange. Myofilament Ca(2+)-sensitivity was significantly higher even with only 5.9 ± 2.5% 199D exchange compared to 199A, and saturated at 12.3 ± 2.6% 199D exchange. Ser199 pseudo-phosphorylation decreased cTnI binding to both actin and actin-tropomyosin. Moreover, altered susceptibility of cTnI to proteolysis by calpain I was found when Ser199 was pseudo-phosphorylated. Our data demonstrate that low levels of cTnI-Ser199 pseudo-phosphorylation (~6%) increase myofilament Ca(2+)-sensitivity in human cardiomyocytes, most likely by decreasing the binding affinity of cTnI for actin-tropomyosin. In addition, cTnI-Ser199 pseudo-phosphorylation or mutation regulates calpain I mediated proteolysis of cTnI.
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Affiliation(s)
- Paul J M Wijnker
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
| | - Yuejin Li
- Department of Pediatrics, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Pingbo Zhang
- Department of Pediatrics, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, USA
| | - D Brian Foster
- Department of Pediatrics, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Cris dos Remedios
- Muscle Research Unit, Bosch Institute, The University of Sydney, Sydney, Australia
| | - Jennifer E Van Eyk
- The Advanced Clinical Biosystems Research Institute, The Heart Institute, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Ger J M Stienen
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands
| | - Anne M Murphy
- Department of Pediatrics, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Jolanda van der Velden
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; ICIN-Netherlands Heart Institute, Utrecht, The Netherlands
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19
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Wei H, Jin JP. NH2-terminal truncations of cardiac troponin I and cardiac troponin T produce distinct effects on contractility and calcium homeostasis in adult cardiomyocytes. Am J Physiol Cell Physiol 2015; 308:C397-404. [PMID: 25518962 PMCID: PMC4346733 DOI: 10.1152/ajpcell.00358.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/10/2014] [Indexed: 12/12/2022]
Abstract
Cardiac troponin I (TnI) has an NH2-terminal extension that is an adult heart-specific regulatory structure. Restrictive proteolytic truncation of the NH2-terminal extension of cardiac TnI occurs in normal hearts and is upregulated in cardiac adaptation to hemodynamic stress or β-adrenergic deficiency. NH2-terminal truncated cardiac TnI (cTnI-ND) alters the conformation of the core structure of cardiac TnI similarly to that produced by PKA phosphorylation of Ser(23/24) in the NH2-terminal extension. At organ level, cTnI-ND enhances ventricular diastolic function. The NH2-terminal region of cardiac troponin T (TnT) is another regulatory structure that can be selectively cleaved via restrictive proteolysis. Structural variations in the NH2-terminal region of TnT also alter the molecular conformation and function. Transgenic mouse hearts expressing NH2-terminal truncated cardiac TnT (cTnT-ND) showed slower contractile velocity to prolong ventricular rapid-ejection time, resulting in higher stroke volume. Our present study compared the effects of cTnI-ND and cTnT-ND in cardiomyocytes isolated from transgenic mice on cellular morphology, contractility, and calcium kinetics. Resting cTnI-ND, but not cTnT-ND, cardiomyocytes had shorter length than wild-type cells with no change in sarcomere length. cTnI-ND, but not cTnT-ND, cardiomyocytes produced higher contractile amplitude and faster shortening and relengthening velocities in the absence of external load than wild-type controls. Although the baseline and peak levels of cytosolic Ca(2+) were not changed, Ca(2+) resequestration was faster in both cTnI-ND and cTnT-ND cardiomyocytes than in wild-type control. The distinct effects of cTnI-ND and cTnT-ND demonstrate their roles in selectively modulating diastolic or systolic functions of the heart.
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Affiliation(s)
- Hongguang Wei
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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20
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Akhter S, Jin JP. Distinct conformational and functional effects of two adjacent pathogenic mutations in cardiac troponin I at the interface with troponin T. FEBS Open Bio 2015; 5:64-75. [PMID: 25685665 PMCID: PMC4325132 DOI: 10.1016/j.fob.2015.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 12/31/2014] [Accepted: 01/02/2015] [Indexed: 11/29/2022] Open
Abstract
Mutations in the TnT-interface of cardiac TnI cause cardiomyopathies. Mutations A117G and K118C resulted in distinct changes in protein conformation. K118C, but not A117G, decreased the binding affinity for TnT. K118C decreased binding affinity for TnC in a Ca2+-dependent manner – A117G had a similar but less profound effect. PKA treatment or N-terminal truncation produces similar changes in cardiac TnI.
The α-helix in troponin I (TnI) at the interface with troponin T (TnT) is a highly conserved structure. A point mutation in this region, A116G, was found in human cardiac TnI in a case of cardiomyopathy. An adjacent dominantly negative mutation found in turkey cardiac TnI (R111C, equivalent to K117C in human and K118C in mouse) decreased diastolic function and blunted beta-adrenergic response in transgenic mice. To investigate the functional importance of the TnI–TnT interface and pathological impact of the cardiac TnI mutations, we engineered K118C and A117G mutations in mouse cardiac TnI for functional studies. Despite their adjacent locations, A117G substitution results in faster mobility of cardiac TnI in SDS–PAGE whereas K118C decreases gel mobility, indicating significant and distinct changes in overall protein conformation. Consistently, monoclonal antibody epitope analysis demonstrated distinct local and remote conformational alterations in the two mutant proteins. Protein binding assays showed that K118C, but not A117G, decreased the relative binding affinity of cardiac TnI for TnT. K118C mutation decreased binding affinity for troponin C in a Ca2+-dependent manner, whereas A117G had a similar but less profound effect. Protein kinase A phosphorylation or truncation to remove the cardiac specific N-terminal extension of cardiac TnI resulted in similar conformational changes in the region interfacing with TnT and minimized the functional impacts of the mutations. The data demonstrate potent conformational and functional impacts of the TnT-interfacing helix in TnI and suggest a role of the N-terminal extension of cardiac TnI in modulating TnI–TnT interface functions.
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Key Words
- BSA, bovine serum albumin
- Cardiac muscle
- ELISA, enzyme linked immunosorbent assay
- McTnI, wild type mouse cardiac TnI
- McTnI-ND, N-terminal truncated mouse cardiac TnI
- McTnI-NDA117G, N-terminal truncated McTnIA117G
- McTnI-NDK118C, N-terminal truncated McTnIK118C
- McTnIA117G, mouse cardiac TnI A117G mutation
- McTnIK118C, mouse cardiac TnI K118C mutation
- PKA, protein kinase A
- Protein conformation
- TnC, troponin C
- TnI, troponin I
- TnT, troponin T
- Troponin
- Troponin I mutation
- Troponin I–Troponin T interface
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Affiliation(s)
- Shirin Akhter
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
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21
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Compartmentalization role of A-kinase anchoring proteins (AKAPs) in mediating protein kinase A (PKA) signaling and cardiomyocyte hypertrophy. Int J Mol Sci 2014. [PMID: 25547489 DOI: 10.3390/ijms16010218.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The Beta-adrenergic receptors (β-ARs) stimulation enhances contractility through protein kinase-A (PKA) substrate phosphorylation. This PKA signaling is conferred in part by PKA binding to A-kinase anchoring proteins (AKAPs). AKAPs coordinate multi-protein signaling networks that are targeted to specific intracellular locations, resulting in the localization of enzyme activity and transmitting intracellular actions of neurotransmitters and hormones to its target substrates. In particular, mAKAP (muscle-selective AKAP) has been shown to be present on the nuclear envelope of cardiomyocytes with various proteins including: PKA-regulatory subunit (RIIα), phosphodiesterase-4D3, protein phosphatase-2A, and ryanodine receptor (RyR2). Therefore, through the coordination of spatial-temporal signaling of proteins and enzymes, mAKAP controls cyclic-adenosine monophosphate (cAMP) levels very tightly and functions as a regulator of PKA-mediated substrate phosphorylation leading to changes in calcium availability and myofilament calcium sensitivity. The goal of this review is to elucidate the critical compartmentalization role of mAKAP in mediating PKA signaling and regulating cardiomyocyte hypertrophy by acting as a scaffolding protein. Based on our literature search and studying the structure-function relationship between AKAP scaffolding protein and its binding partners, we propose possible explanations for the mechanism by which mAKAP promotes cardiac hypertrophy.
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Rababa'h A, Singh S, Suryavanshi SV, Altarabsheh SE, Deo SV, McConnell BK. Compartmentalization role of A-kinase anchoring proteins (AKAPs) in mediating protein kinase A (PKA) signaling and cardiomyocyte hypertrophy. Int J Mol Sci 2014; 16:218-29. [PMID: 25547489 PMCID: PMC4307244 DOI: 10.3390/ijms16010218] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/18/2014] [Indexed: 02/07/2023] Open
Abstract
The Beta-adrenergic receptors (β-ARs) stimulation enhances contractility through protein kinase-A (PKA) substrate phosphorylation. This PKA signaling is conferred in part by PKA binding to A-kinase anchoring proteins (AKAPs). AKAPs coordinate multi-protein signaling networks that are targeted to specific intracellular locations, resulting in the localization of enzyme activity and transmitting intracellular actions of neurotransmitters and hormones to its target substrates. In particular, mAKAP (muscle-selective AKAP) has been shown to be present on the nuclear envelope of cardiomyocytes with various proteins including: PKA-regulatory subunit (RIIα), phosphodiesterase-4D3, protein phosphatase-2A, and ryanodine receptor (RyR2). Therefore, through the coordination of spatial-temporal signaling of proteins and enzymes, mAKAP controls cyclic-adenosine monophosphate (cAMP) levels very tightly and functions as a regulator of PKA-mediated substrate phosphorylation leading to changes in calcium availability and myofilament calcium sensitivity. The goal of this review is to elucidate the critical compartmentalization role of mAKAP in mediating PKA signaling and regulating cardiomyocyte hypertrophy by acting as a scaffolding protein. Based on our literature search and studying the structure-function relationship between AKAP scaffolding protein and its binding partners, we propose possible explanations for the mechanism by which mAKAP promotes cardiac hypertrophy.
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Affiliation(s)
- Abeer Rababa'h
- Department of Clinical Pharmacy, Jordan University of Science and Technology, Irbid 22110, Jordan.
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA.
| | - Santosh V Suryavanshi
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA.
| | | | - Salil V Deo
- Department of Cardiovascular Surgery, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA.
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23
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Li X, Matta SM, Sullivan RD, Bahouth SW. Carvedilol reverses cardiac insufficiency in AKAP5 knockout mice by normalizing the activities of calcineurin and CaMKII. Cardiovasc Res 2014; 104:270-9. [PMID: 25225170 DOI: 10.1093/cvr/cvu209] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
AIMS Cardiac β-adrenergic receptors (β-AR) are key regulators of cardiac haemodynamics and size. The scaffolding protein A-kinase anchoring protein 79/150 (AKAP5) is a key regulator of myocardial signalling by β-ARs. We examined the function of AKAP5 in regulating cardiac haemodynamics and size, and the role of β-ARs and Ca(2+)-regulated intracellular signalling pathways in this phenomenon. METHODS AND RESULTS We used echocardiographic, histological, genetic, and biochemical methods to examine the effect of ablation of AKAP5 on cardiac haemodynamics, size, and signalling in mice. AKAP5(-/-) mice exhibited enhanced signs of cardiac dilatation and dysfunction that progressed with age. Infusions of isoprenaline worsened cardiac haemodynamics in wild-type (WT) mice only, but increased the ratio of heart-to-body weight equally in WT and in AKAP5(-/-) mice. Mechanistically, loss of AKAP5 was associated with enhanced activity of cardiac calmodulin kinase II (CaMKII) and calcineurin (CaN) as indexed by nuclear factor of activated T-cell-luciferase activity. Loss of AKAP5 interfered with the recycling of cardiac β1-ARs, which was mediated in part by CaN binding to AKAP5. Carvedilol reversed cardiac hypertrophy and haemodynamic deficiencies in AKAP5(-/-) mice by normalizing the activities of cardiac CaN and CaMKII. CONCLUSIONS These findings identify a novel cardioprotective role for AKAP5 that is mediated by regulating the activities of cardiac CaN and CaMKII and highlight a significant role for cardiac β-ARs in this phenomenon.
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Affiliation(s)
- Xin Li
- Department of Pharmacology, The University of Tennessee Health Sciences Center, 874 Union Avenue, Memphis, TN 38163, USA
| | - Shannon M Matta
- Department of Pharmacology, The University of Tennessee Health Sciences Center, 874 Union Avenue, Memphis, TN 38163, USA
| | - Ryan D Sullivan
- Department of Comparative Medicine, The University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - Suleiman W Bahouth
- Department of Pharmacology, The University of Tennessee Health Sciences Center, 874 Union Avenue, Memphis, TN 38163, USA
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24
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Kapiloff MS, Rigatti M, Dodge-Kafka KL. Architectural and functional roles of A kinase-anchoring proteins in cAMP microdomains. ACTA ACUST UNITED AC 2014; 143:9-15. [PMID: 24378903 PMCID: PMC3874566 DOI: 10.1085/jgp.201311020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Michael S Kapiloff
- Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, 2 Department of Pediatrics, and 3 Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33101
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25
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Lorenz K, Stathopoulou K, Schmid E, Eder P, Cuello F. Heart failure-specific changes in protein kinase signalling. Pflugers Arch 2014; 466:1151-62. [DOI: 10.1007/s00424-014-1462-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 01/19/2014] [Accepted: 01/22/2014] [Indexed: 01/14/2023]
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26
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Motawea HKB, Blazek AD, Zirwas MJ, Pleister AP, Ahmed AAE, McConnell BK, Chotani MA. Delocalization of Endogenous A-kinase Antagonizes Rap1-Rho-α 2C-Adrenoceptor Signaling in Human Microvascular Smooth Muscle Cells. JOURNAL OF CYTOLOGY & MOLECULAR BIOLOGY 2014; 1:1000002. [PMID: 24701590 PMCID: PMC3970818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The second messenger cyclic AMP (cAMP) plays a vital role in the physiology of the cardiovascular system, including vasodilation of large blood vessels. This study focused on cAMP signaling in peripheral blood vessels, specifically in human vascular smooth muscle (microVSM) cells explanted from skin punch biopsy arterioles (also known as resistance vessels) of healthy volunteers. Using these human microVSM we recently demonstrated cAMP activation of exchange protein activated by cAMP (Epac), the Ras-related small GTPase Rap1A, and RhoA-ROCK-F-actin signaling in human microVSM to increase expression and cell surface translocation of functional α2C-adrenoceptors (α2C-ARs) that mediate vasoconstriction. Protein-protein association with the actin-binding protein filamin-2 and phosphorylation of filamin-2 Ser2113 by cAMP-Rap1A-Rho-ROCK signaling were necessary for receptor translocation in these cells. Although cAMP activated A-kinase in these cells, these effects were independent of A-kinase, and suggested compartmentalized A-kinase local signaling facilitated by A-kinase anchoring proteins (AKAPs). In this study we globally disrupted A-kinase-AKAP interactions by the anchoring inhibitor decoy peptide Ht31 and examined the effect on α2C-AR expression, translocation, and function in quiescent microVSM treated with the adenylyl cyclase activator and cAMP elevating agent forskolin. The results show that Ht31, but not the control peptide Ht31-P, reduced forskolin-stimulated Ser133 phosphorylation of A-kinase substrate CREB, reduced α2C-AR mRNA levels, reduced cell surface translocated receptors, and attenuated agonist-triggered receptor functional responses. Together, the results suggest that compartmentalized cAMP signaling elicits a selective cellular response in microVSM, which may have relevance to arteriole physiological function and responses.
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Affiliation(s)
- Hanaa K. B. Motawea
- Center for Cardiovascular & Pulmonary Research, The Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, USA
- Faculty of Pharmacy, Department of Pharmacology & Toxicology, Helwan University, Helwan, Egypt
| | - Alisa D. Blazek
- Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio, USA
| | - Matthew J. Zirwas
- Internal Medicine, Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Adam P. Pleister
- Internal Medicine, Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Amany A. E. Ahmed
- Faculty of Pharmacy, Department of Pharmacology & Toxicology, Helwan University, Helwan, Egypt
| | - Bradley K. McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, Texas, USA
| | - Maqsood A. Chotani
- Center for Cardiovascular & Pulmonary Research, The Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, USA
- Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio, USA
- Department of Pediatrics, Ohio State University, Columbus, Ohio, USA
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27
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Esseltine JL, Scott JD. AKAP signaling complexes: pointing towards the next generation of therapeutic targets? Trends Pharmacol Sci 2013; 34:648-55. [PMID: 24239028 DOI: 10.1016/j.tips.2013.10.005] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/11/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
A-kinase anchoring proteins (AKAPs) streamline signal transduction by localizing signaling enzymes with their substrates. Great strides have been made in elucidating the role of these macromolecular signaling complexes as new binding partners and novel AKAPs are continually being uncovered. The mechanics and dynamics of these multi-enzyme assemblies suggest that AKAP complexes are viable targets for therapeutic intervention. This review will highlight recent advances in AKAP research focusing on local signaling events that are perturbed in disease.
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Affiliation(s)
- Jessica L Esseltine
- Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA
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28
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Kijtawornrat A, Ueyama Y, del Rio C, Sawangkoon S, Buranakarl C, Chaiyabutr N, Hamlin RL. Test of the usefulness of a paradigm to identify potential cardiovascular liabilities of four test articles with varying pharmacological properties in anesthetized guinea pigs. Toxicol Sci 2013; 137:458-68. [PMID: 24189130 DOI: 10.1093/toxsci/kft244] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The evaluation of proarrhythmic and hemodynamic liabilities for new compounds remains a major concern of preclinical safety assessment paradigms. Contrastingly, albeit functional liabilities can also translate to clinical morbidity and mortality, lesser preclinical efforts are focused on the evaluation of drug-induced changes in inotrope and lusitrope, particularly in the setting of concomitant hemodynamic/arrhythmic liabilities. This study aimed to establish the feasibility of an anesthetized guinea pig preparation to assess functional liabilities in the setting of simultaneous drug-induced electrocardiographic/hemodynamic changes, by evaluating the effects of various compounds with known cardiovascular properties on direct and indirect indices of left ventricular function. In short, twenty nine male guinea pigs were instrumented to measure electrocardiograms, systemic arterial pressure, and left ventricular pressure-volume relationships. After baseline measurement, all animals were given intravenous infusions of vehicle and two escalating concentrations of either chromanol 293B (n = 8), milrinone (n = 6), metoprolol (n = 7), or nicorandil (n = 8) for 10 minutes each. In all cases, these compounds produced the expected changes. The slope of preload-recruitable stroke work (PRSW), a pressure-volume derived load independent index, was the most sensitive marker of drug-induced changes in inotropy. Among the indirect functional indices studied, only the "contractility index" (dP/dtmax normalized by the pressure at its occurrence) and the static myocardial compliance (ratio of end diastolic volume and pressure) appeared to be adequate predictors of drug-induced changes in inotropy/lusitropy. Overall, the data confirms that both electrophysiological and mechanical liabilities can be accurately assessed in an anesthetized guinea pig preparation.
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Affiliation(s)
- Anusak Kijtawornrat
- * Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
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29
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Enhanced cardiac function in Gravin mutant mice involves alterations in the β-adrenergic receptor signaling cascade. PLoS One 2013. [PMID: 24058627 DOI: 10.1371/journal.pone.0074784.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Gravin, an A-kinase anchoring protein, targets protein kinase A (PKA), protein kinase C (PKC), calcineurin and other signaling molecules to the beta2-adrenergic receptor (β2-AR). Gravin mediates desensitization/resensitization of the receptor by facilitating its phosphorylation by PKA and PKC. The role of gravin in β-AR mediated regulation of cardiac function is unclear. The purpose of this study was to determine the effect of acute β-AR stimulation on cardiac contractility in mice lacking functional gravin. Using echocardiographic analysis, we observed that contractility parameters such as left ventricular fractional shortening and ejection fraction were increased in gravin mutant (gravin-t/t) animals lacking functional protein compared to wild-type (WT) animals both at baseline and following acute isoproterenol (ISO) administration. In isolated gravin-t/t cardiomyocytes, we observed increased cell shortening fraction and decreased intracellular Ca(2+) in response to 1 µmol/L ISO stimulation. These physiological responses occurred in the presence of decreased β2-AR phosphorylation in gravin-t/t hearts, where PKA-dependent β2-AR phosphorylation has been shown to lead to receptor desensitization. cAMP production, PKA activity and phosphorylation of phospholamban and troponin I was comparable in WT and gravin-t/t hearts both with and without ISO stimulation. However, cardiac myosin binding protein C (cMyBPC) phosphorylation site at position 273 was significantly increased in gravin-t/t versus WT hearts, in the absence of ISO. Additionally, the cardioprotective heat shock protein 20 (Hsp20) was significantly more phosphorylated in gravin-t/t versus WT hearts, in response to ISO. Our results suggest that disruption of gravin's scaffold mediated signaling is able to increase baseline cardiac function as well as to augment contractility in response to acute β-AR stimulation by decreasing β2-AR phosphorylation and thus attenuating receptor desensitization and perhaps by altering PKA localization to increase the phosphorylation of cMyBPC and the nonclassical PKA substrate Hsp20.
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30
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Rababa'h A, Craft JW, Wijaya CS, Atrooz F, Fan Q, Singh S, Guillory AN, Katsonis P, Lichtarge O, McConnell BK. Protein kinase A and phosphodiesterase-4D3 binding to coding polymorphisms of cardiac muscle anchoring protein (mAKAP). J Mol Biol 2013. [PMID: 23806656 DOI: 10.1016/j.jmb.2013.06.014.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
Abstract
Protein kinase A (PKA) substrate phosphorylation is facilitated through its co-localization with its signaling partner by A-kinase anchoring proteins (AKAPs). mAKAP (muscle-selective AKAP) localizes PKA and its substrates such as phosphodiesterase-4D3 (PDE4D3), ryanodine receptor, and protein phosphatase 2A (PP2A) to the sarcoplasmic reticulum and perinuclear space. The genetic role of mAKAP, in modulating PKA/PDE4D3 molecular signaling during cardiac diseases, remains unclear. The purpose of this study was to examine the effects of naturally occurring mutations in human mAKAP on PKA and PDE4D3 signaling. We have recently identified potentially important human mAKAP coding non-synonymous polymorphisms located within or near key protein binding sites critical to β-adrenergic receptor signaling. Three mutations (P1400S, S2195F, and L717V) were cloned and transfected into a mammalian cell line for the purpose of comparing whether those substitutions disrupt mAKAP binding to PKA or PDE4D3. Immunoprecipitation study of mAKAP-P1400S, a mutation located in the mAKAP-PDE4D3 binding site, displayed a significant reduction in binding to PDE4D3, with no significant changes in PKA binding or PKA activity. Conversely, mAKAP-S2195F, a mutation located in mAKAP-PP2A binding site, showed significant increase in both binding propensity to PKA and PKA activity. Additionally, mAKAP-L717V, a mutation flanking the mAKAP-spectrin repeat domain, exhibited a significant increase in PKA binding compared to wild type, but there was no change in PKA activity. We also demonstrate specific binding of wild-type mAKAP to PDE4D3. Binding results were demonstrated using immunoprecipitation and confirmed with surface plasmon resonance (Biacore-2000); functional results were demonstrated using activity assays, Ca(2+) measurements, and Western blot. Comparative analysis of the binding responses of mutations to mAKAP could provide important information about how these mutations modulate signaling.
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Affiliation(s)
- Abeer Rababa'h
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA
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31
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Guillory AN, Yin X, Wijaya CS, Diaz Diaz AC, Rababa’h A, Singh S, Atrooz F, Sadayappan S, McConnell BK. Enhanced cardiac function in Gravin mutant mice involves alterations in the β-adrenergic receptor signaling cascade. PLoS One 2013; 8:e74784. [PMID: 24058627 PMCID: PMC3776749 DOI: 10.1371/journal.pone.0074784] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 08/07/2013] [Indexed: 11/19/2022] Open
Abstract
Gravin, an A-kinase anchoring protein, targets protein kinase A (PKA), protein kinase C (PKC), calcineurin and other signaling molecules to the beta2-adrenergic receptor (β2-AR). Gravin mediates desensitization/resensitization of the receptor by facilitating its phosphorylation by PKA and PKC. The role of gravin in β-AR mediated regulation of cardiac function is unclear. The purpose of this study was to determine the effect of acute β-AR stimulation on cardiac contractility in mice lacking functional gravin. Using echocardiographic analysis, we observed that contractility parameters such as left ventricular fractional shortening and ejection fraction were increased in gravin mutant (gravin-t/t) animals lacking functional protein compared to wild-type (WT) animals both at baseline and following acute isoproterenol (ISO) administration. In isolated gravin-t/t cardiomyocytes, we observed increased cell shortening fraction and decreased intracellular Ca2+ in response to 1 µmol/L ISO stimulation. These physiological responses occurred in the presence of decreased β2-AR phosphorylation in gravin-t/t hearts, where PKA-dependent β2-AR phosphorylation has been shown to lead to receptor desensitization. cAMP production, PKA activity and phosphorylation of phospholamban and troponin I was comparable in WT and gravin-t/t hearts both with and without ISO stimulation. However, cardiac myosin binding protein C (cMyBPC) phosphorylation site at position 273 was significantly increased in gravin-t/t versus WT hearts, in the absence of ISO. Additionally, the cardioprotective heat shock protein 20 (Hsp20) was significantly more phosphorylated in gravin-t/t versus WT hearts, in response to ISO. Our results suggest that disruption of gravin’s scaffold mediated signaling is able to increase baseline cardiac function as well as to augment contractility in response to acute β-AR stimulation by decreasing β2-AR phosphorylation and thus attenuating receptor desensitization and perhaps by altering PKA localization to increase the phosphorylation of cMyBPC and the nonclassical PKA substrate Hsp20.
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Affiliation(s)
- Ashley N. Guillory
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Xing Yin
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Cori S. Wijaya
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Andrea C. Diaz Diaz
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Abeer Rababa’h
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Fatin Atrooz
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois, United States of America
| | - Bradley K. McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
- * E-mail:
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32
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Targeting protein-protein interactions within the cyclic AMP signaling system as a therapeutic strategy for cardiovascular disease. Future Med Chem 2013; 5:451-64. [PMID: 23495691 DOI: 10.4155/fmc.12.216] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The cAMP signaling system can trigger precise physiological cellular responses that depend on the fidelity of many protein-protein interactions, which act to bring together signaling intermediates at defined locations within cells. In the heart, cAMP participates in the fine control of excitation-contraction coupling, hence, any disregulation of this signaling cascade can lead to cardiac disease. Due to the ubiquitous nature of the cAMP pathway, general inhibitors of cAMP signaling proteins such as PKA, EPAC and PDEs would act non-specifically and universally, increasing the likelihood of serious 'off target' effects. Recent advances in the discovery of peptides and small molecules that disrupt the protein-protein interactions that underpin cellular targeting of cAMP signaling proteins are described and discussed.
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33
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Protein kinase A and phosphodiesterase-4D3 binding to coding polymorphisms of cardiac muscle anchoring protein (mAKAP). J Mol Biol 2013; 425:3277-88. [PMID: 23806656 DOI: 10.1016/j.jmb.2013.06.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 05/20/2013] [Accepted: 06/11/2013] [Indexed: 11/20/2022]
Abstract
Protein kinase A (PKA) substrate phosphorylation is facilitated through its co-localization with its signaling partner by A-kinase anchoring proteins (AKAPs). mAKAP (muscle-selective AKAP) localizes PKA and its substrates such as phosphodiesterase-4D3 (PDE4D3), ryanodine receptor, and protein phosphatase 2A (PP2A) to the sarcoplasmic reticulum and perinuclear space. The genetic role of mAKAP, in modulating PKA/PDE4D3 molecular signaling during cardiac diseases, remains unclear. The purpose of this study was to examine the effects of naturally occurring mutations in human mAKAP on PKA and PDE4D3 signaling. We have recently identified potentially important human mAKAP coding non-synonymous polymorphisms located within or near key protein binding sites critical to β-adrenergic receptor signaling. Three mutations (P1400S, S2195F, and L717V) were cloned and transfected into a mammalian cell line for the purpose of comparing whether those substitutions disrupt mAKAP binding to PKA or PDE4D3. Immunoprecipitation study of mAKAP-P1400S, a mutation located in the mAKAP-PDE4D3 binding site, displayed a significant reduction in binding to PDE4D3, with no significant changes in PKA binding or PKA activity. Conversely, mAKAP-S2195F, a mutation located in mAKAP-PP2A binding site, showed significant increase in both binding propensity to PKA and PKA activity. Additionally, mAKAP-L717V, a mutation flanking the mAKAP-spectrin repeat domain, exhibited a significant increase in PKA binding compared to wild type, but there was no change in PKA activity. We also demonstrate specific binding of wild-type mAKAP to PDE4D3. Binding results were demonstrated using immunoprecipitation and confirmed with surface plasmon resonance (Biacore-2000); functional results were demonstrated using activity assays, Ca(2+) measurements, and Western blot. Comparative analysis of the binding responses of mutations to mAKAP could provide important information about how these mutations modulate signaling.
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34
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Spindler MJ, Burmeister BT, Huang Y, Hsiao EC, Salomonis N, Scott MJ, Srivastava D, Carnegie GK, Conklin BR. AKAP13 Rho-GEF and PKD-binding domain deficient mice develop normally but have an abnormal response to β-adrenergic-induced cardiac hypertrophy. PLoS One 2013; 8:e62705. [PMID: 23658642 PMCID: PMC3637253 DOI: 10.1371/journal.pone.0062705] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 03/28/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND A-kinase anchoring proteins (AKAPs) are scaffolding molecules that coordinate and integrate G-protein signaling events to regulate development, physiology, and disease. One family member, AKAP13, encodes for multiple protein isoforms that contain binding sites for protein kinase A (PKA) and D (PKD) and an active Rho-guanine nucleotide exchange factor (Rho-GEF) domain. In mice, AKAP13 is required for development as null embryos die by embryonic day 10.5 with cardiovascular phenotypes. Additionally, the AKAP13 Rho-GEF and PKD-binding domains mediate cardiomyocyte hypertrophy in cell culture. However, the requirements for the Rho-GEF and PKD-binding domains during development and cardiac hypertrophy are unknown. METHODOLOGY/PRINCIPAL FINDINGS To determine if these AKAP13 protein domains are required for development, we used gene-trap events to create mutant mice that lacked the Rho-GEF and/or the protein kinase D-binding domains. Surprisingly, heterozygous matings produced mutant mice at Mendelian ratios that had normal viability and fertility. The adult mutant mice also had normal cardiac structure and electrocardiograms. To determine the role of these domains during β-adrenergic-induced cardiac hypertrophy, we stressed the mice with isoproterenol. We found that heart size was increased similarly in mice lacking the Rho-GEF and PKD-binding domains and wild-type controls. However, the mutant hearts had abnormal cardiac contractility as measured by fractional shortening and ejection fraction. CONCLUSIONS These results indicate that the Rho-GEF and PKD-binding domains of AKAP13 are not required for mouse development, normal cardiac architecture, or β-adrenergic-induced cardiac hypertrophic remodeling. However, these domains regulate aspects of β-adrenergic-induced cardiac hypertrophy.
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Affiliation(s)
- Matthew J Spindler
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA.
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35
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Abstract
Spatial and temporal organization of signal transduction is coordinated through the segregation of signaling enzymes in selected cellular compartments. This highly evolved regulatory mechanism ensures the activation of selected enzymes only in the vicinity of their target proteins. In this context, cAMP-responsive triggering of protein kinase A is modulated by a family of scaffold proteins referred to as A-kinase anchoring proteins. A-kinase anchoring proteins form the core of multiprotein complexes and enable simultaneous but segregated cAMP signaling events to occur in defined cellular compartments. In this review we will focus on the description of A-kinase anchoring protein function in the regulation of cardiac physiopathology.
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Affiliation(s)
- Alessia Perino
- Molecular Biotechnology Center, Department of Genetics, Biology and Biochemistry, University of Torino, Torino, Italy
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36
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Scott JD, Dessauer CW, Taskén K. Creating order from chaos: cellular regulation by kinase anchoring. Annu Rev Pharmacol Toxicol 2012; 53:187-210. [PMID: 23043438 DOI: 10.1146/annurev-pharmtox-011112-140204] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Second messenger responses rely on where and when the enzymes that propagate these signals become active. Spatial and temporal organization of certain signaling enzymes is controlled in part by A-kinase anchoring proteins (AKAPs). This family of regulatory proteins was originally classified on the basis of their ability to compartmentalize the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (also known as protein kinase A, or PKA). However, it is now recognized that AKAPs position G protein-coupled receptors, adenylyl cyclases, G proteins, and their effector proteins in relation to protein kinases and signal termination enzymes such as phosphodiesterases and protein phosphatases. This arrangement offers a simple and efficient means to limit the scope, duration, and directional flow of information to sites deep within the cell. This review focuses on the pros and cons of reagents that define the biological role of kinase anchoring inside cells and discusses recent advances in our understanding of anchored second messenger signaling in the cardiovascular and immune systems.
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Affiliation(s)
- John D Scott
- Howard Hughes Medical Institute and Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195, USA.
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37
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Cardiomyocytes from AKAP7 knockout mice respond normally to adrenergic stimulation. Proc Natl Acad Sci U S A 2012; 109:17099-104. [PMID: 23035250 DOI: 10.1073/pnas.1215219109] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein kinase A (PKA) is activated during sympathetic stimulation of the heart and phosphorylates key proteins involved in cardiac Ca(2+) handling, including the L-type Ca(2+) channel (Ca(V)1.2) and phospholamban (PLN). This results in acceleration and amplification of the beat-to-beat changes in cytosolic Ca(2+) in cardiomyocytes and, in turn, an increased rate and force of contraction. PKA is held in proximity to its substrates by protein scaffolds called A kinase anchoring proteins (AKAPs). It has been suggested that the short and long isoforms of AKAP7 (also called AKAP15/18) localize PKA in complexes with Ca(V)1.2 and PLN, respectively. We generated an AKAP7 KO mouse in which all isoforms were deleted and tested whether Ca(2+) current, intracellular Ca(2+) concentration, or Ca(2+) reuptake were impaired in isolated adult ventricular cardiomyocytes following stimulation with the β-adrenergic agonist isoproterenol. KO cardiomyocytes responded normally to adrenergic stimulation, as measured by whole-cell patch clamp or a fluorescent intracellular Ca(2+) indicator. Phosphorylation of Ca(V)1.2 and PLN were also unaffected by genetic deletion of AKAP7. Immunoblot and RT-PCR revealed that only the long isoforms of AKAP7 were detectable in ventricular cardiomyocytes. The results indicate that AKAP7 is not required for regulation of Ca(2+) handling in mouse cardiomyocytes.
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Tröger J, Moutty MC, Skroblin P, Klussmann E. A-kinase anchoring proteins as potential drug targets. Br J Pharmacol 2012; 166:420-33. [PMID: 22122509 DOI: 10.1111/j.1476-5381.2011.01796.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A-kinase anchoring proteins (AKAPs) crucially contribute to the spatial and temporal control of cellular signalling. They directly interact with a variety of protein binding partners and cellular constituents, thereby directing pools of signalling components to defined locales. In particular, AKAPs mediate compartmentalization of cAMP signalling. Alterations in AKAP expression and their interactions are associated with or cause diseases including chronic heart failure, various cancers and disorders of the immune system such as HIV. A number of cellular dysfunctions result from mutations of specific AKAPs. The link between malfunctions of single AKAP complexes and a disease makes AKAPs and their interactions interesting targets for the development of novel drugs. LINKED ARTICLES This article is part of a themed section on Novel cAMP Signalling Paradigms. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.166.issue-2.
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Affiliation(s)
- Jessica Tröger
- Max Delbrück Center for Molecular Medicine Berlin-Buch (MDC), Berlin, Germany Leibniz Institute for Molecular Pharmacology (FMP), Berlin, Germany
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Insights into restrictive cardiomyopathy from clinical and animal studies. J Geriatr Cardiol 2012; 8:168-83. [PMID: 22783303 PMCID: PMC3390071 DOI: 10.3724/sp.j.1263.2011.00168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 08/24/2011] [Accepted: 08/31/2011] [Indexed: 01/13/2023] Open
Abstract
Cardiomyopathies are diseases that primarily affect the myocardium, leading to serious cardiac dysfunction and heart failure. Out of the three major categories of cardiomyopathies (hypertrophic, dilated and restrictive), restrictive cardiomyopathy (RCM) is less common and also the least studied. However, the prognosis for RCM is poor as some patients dying in their childhood. The molecular mechanisms behind the disease development and progression are not very clear and the treatment of RCM is very difficult and often ineffective. In this article, we reviewed the recent progress in RCM research from the clinical studies and the translational studies done on diseased transgenic animal models. This will help for a better understanding of the mechanisms underlying the etiology and development of RCM and for the design of better treatments for the disease.
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Diviani D, Maric D, Pérez López I, Cavin S, Del Vescovo CD. A-kinase anchoring proteins: molecular regulators of the cardiac stress response. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:901-8. [PMID: 22889610 DOI: 10.1016/j.bbamcr.2012.07.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 07/26/2012] [Accepted: 07/29/2012] [Indexed: 12/29/2022]
Abstract
In response to stress or injury the heart undergoes a pathological remodeling process, associated with hypertrophy, cardiomyocyte death and fibrosis, that ultimately causes cardiac dysfunction and heart failure. It has become increasingly clear that signaling events associated with these pathological cardiac remodeling events are regulated by scaffolding and anchoring proteins, which allow coordination of pathological signals in space and time. A-kinase anchoring proteins (AKAPs) constitute a family of functionally related proteins that organize multiprotein signaling complexes that tether the cAMP-dependent protein kinase (PKA) as well as other signaling enzymes to ensure integration and processing of multiple signaling pathways. This review will discuss the role of AKAPs in the cardiac response to stress. Particular emphasis will be given to the adaptative process associated with cardiac hypoxia as well as the remodeling events linked to cardiac hypertrophy and heart failure. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
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Affiliation(s)
- Dario Diviani
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et Médecine, Lausanne, Switzerland.
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Abstract
3'-5'-Cyclic adenosine monophosphate (cAMP), generated by adenylyl cyclase (AC), serves as a second messenger in signaling pathways regulating many aspects of cardiac physiology, including contraction rate and action potential duration, and in the pathophysiology of hypertrophy and heart failure. A kinase-anchoring proteins localize the effect of cAMP in space and time by organizing receptors, AC, protein kinase A, and other components of the cAMP cascade into multiprotein complexes. In this review, we discuss how the interaction of A kinase-anchoring proteins with distinct AC isoforms affects cardiovascular physiology.
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Human Tau may Modify Glucocorticoids-Mediated Regulation of cAMP-dependent Kinase and Phosphorylated cAMP Response Element Binding Protein. Neurochem Res 2012; 37:935-47. [DOI: 10.1007/s11064-011-0686-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/14/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
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Abstract
Cyclic adenosine 3',5'-monophosphate (cAMP) mediates the biological effects of various hormones and neurotransmitters. Stimulation of cardiac β-adrenergic receptors (β-AR) via catecholamines leads to activation of adenylyl cyclases and increases cAMP production to enhance myocardial function. Because many other receptors signaling through cAMP generation exist in cardiac myocytes, a central question is how different hormones induce distinct cellular responses through the same second messenger. A large body of evidence suggests that the localization and compartmentalization of β-AR/cAMP signaling affects the net outcome of biological functions. Spatiotemporal dynamics of cAMP action is achieved by various proteins, including protein kinase A (PKA), phosphodiesterases, and scaffolding proteins such as A-kinase-anchoring proteins. In addition, the discovery of the cAMP target Epac (exchange proteins directly activated by cAMP), which functions in a PKA-independent manner, represents a novel mechanism for governing cAMP-signaling specificity. Aberrant cAMP signaling through dysregulation of β-AR/cAMP compartmentalization may contribute to cardiac remodeling and heart failure.
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Affiliation(s)
- Magali Berthouze
- INSERM, UMR-1048, Institut des Maladies Métaboliques et Cardiovasculaires, 1 Avenue Jean Poulhès, BP 84225, 31342, Toulouse Cedex 4, France
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Akhter S, Zhang Z, Jin JP. The heart-specific NH2-terminal extension regulates the molecular conformation and function of cardiac troponin I. Am J Physiol Heart Circ Physiol 2011; 302:H923-33. [PMID: 22140044 DOI: 10.1152/ajpheart.00637.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In addition to the core structure conserved in all troponin I isoforms, cardiac troponin I (cTnI) has an ∼30 amino acids NH(2)-terminal extension. This peptide segment is a heart-specific regulatory structure containing two Ser residues that are substrates of PKA. Under β-adrenergic regulation, phosphorylation of cTnI in the NH(2)-terminal extension increases the rate of myocardial relaxation. The NH(2)-terminal extension of cTnI is also removable by restrictive proteolysis to produce functional adaptation to hemodynamic stresses. The molecular mechanism for the NH(2)-terminal modifications to regulate the function of cTnI is not fully understood. In the present study, we tested a hypothesis that the NH(2)-terminal extension functions by modulating the conformation of other regions of cTnI. Monoclonal antibody epitope analysis and protein binding experiments demonstrated that deletion of the NH(2)-terminal segment altered epitopic conformation in the middle, but not COOH-terminal, region of cTnI. PKA phosphorylation produced similar effects. This targeted long-range conformational modulation corresponded to changes in the binding affinities of cTnI for troponin T and for troponin C in a Ca(2+)-dependent manner. The data suggest that the NH(2)-terminal extension of cTnI regulates cardiac muscle function through modulating molecular conformation and function of the core structure of cTnI.
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Affiliation(s)
- Shirin Akhter
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Diviani D, Dodge-Kafka KL, Li J, Kapiloff MS. A-kinase anchoring proteins: scaffolding proteins in the heart. Am J Physiol Heart Circ Physiol 2011; 301:H1742-53. [PMID: 21856912 DOI: 10.1152/ajpheart.00569.2011] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The pleiotropic cyclic nucleotide cAMP is the primary second messenger responsible for autonomic regulation of cardiac inotropy, chronotropy, and lusitropy. Under conditions of prolonged catecholaminergic stimulation, cAMP also contributes to the induction of both cardiac myocyte hypertrophy and apoptosis. The formation of localized, multiprotein complexes that contain different combinations of cAMP effectors and regulatory enzymes provides the architectural infrastructure for the specialization of the cAMP signaling network. Scaffolds that bind protein kinase A are called "A-kinase anchoring proteins" (AKAPs). In this review, we discuss recent advances in our understanding of how PKA is compartmentalized within the cardiac myocyte by AKAPs and how AKAP complexes modulate cardiac function in both health and disease.
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Affiliation(s)
- Dario Diviani
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et Médecine, Université de Lausanne, Lausanne, Switzerland.
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46
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AKAPs: the architectural underpinnings of local cAMP signaling. J Mol Cell Cardiol 2011; 52:351-8. [PMID: 21600214 DOI: 10.1016/j.yjmcc.2011.05.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/28/2011] [Accepted: 05/03/2011] [Indexed: 12/13/2022]
Abstract
The cAMP-dependent protein kinase A (PKA) is targeted to specific compartments in the cardiac myocyte by A-kinase anchoring proteins (AKAPs), a diverse set of scaffold proteins that have been implicated in the regulation of excitation-contraction coupling and cardiac remodeling. AKAPs bind not only PKA, but also a large variety of structural and signaling molecules. In this review, we discuss the basic concepts underlying compartmentation of cAMP and PKA signaling, as well as a few of the individual AKAPs that have been shown to be functionally relevant in the heart. This article is part of a Special Issue entitled "Local Signaling in Myocytes".
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47
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Uys GM, Ramburan A, Loos B, Kinnear CJ, Korkie LJ, Mouton J, Riedemann J, Moolman-Smook JC. Myomegalin is a novel A-kinase anchoring protein involved in the phosphorylation of cardiac myosin binding protein C. BMC Cell Biol 2011; 12:18. [PMID: 21569246 PMCID: PMC3103437 DOI: 10.1186/1471-2121-12-18] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 05/10/2011] [Indexed: 12/29/2022] Open
Abstract
Background Cardiac contractility is regulated by dynamic phosphorylation of sarcomeric proteins by kinases such as cAMP-activated protein kinase A (PKA). Efficient phosphorylation requires that PKA be anchored close to its targets by A-kinase anchoring proteins (AKAPs). Cardiac Myosin Binding Protein-C (cMyBPC) and cardiac troponin I (cTNI) are hypertrophic cardiomyopathy (HCM)-causing sarcomeric proteins which regulate contractility in response to PKA phosphorylation. Results During a yeast 2-hybrid (Y2H) library screen using a trisphosphorylation mimic of the C1-C2 region of cMyBPC, we identified isoform 4 of myomegalin (MMGL) as an interactor of this N-terminal cMyBPC region. As MMGL has previously been shown to interact with phosphodiesterase 4D, we speculated that it may be a PKA-anchoring protein (AKAP). To investigate this possibility, we assessed the ability of MMGL isoform 4 to interact with PKA regulatory subunits R1A and R2A using Y2H-based direct protein-protein interaction assays. Additionally, to further elucidate the function of MMGL, we used it as bait to screen a cardiac cDNA library. Other PKA targets, viz. CARP, COMMD4, ENO1, ENO3 and cTNI were identified as putative interactors, with cTNI being the most frequent interactor. We further assessed and confirmed these interactions by fluorescent 3D-co-localization in differentiated H9C2 cells as well as by in vivo co-immunoprecipitation. We also showed that quantitatively more interaction occurs between MMGL and cTNI under β-adrenergic stress. Moreover, siRNA-mediated knockdown of MMGL leads to reduction of cMyBPC levels under conditions of adrenergic stress, indicating that MMGL-assisted phosphorylation is requisite for protection of cMyBPC against proteolytic cleavage. Conclusions This study ascribes a novel function to MMGL isoform 4: it meets all criteria for classification as an AKAP, and we show that is involved in the phosphorylation of cMyBPC as well as cTNI, hence MMGL is an important regulator of cardiac contractility. This has further implications for understanding the patho-aetiology of HCM-causing mutations in the genes encoding cMyBPC and cTNI, and raises the question of whether MMGL might itself be considered a candidate HCM-causing or modifying factor.
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Affiliation(s)
- Gerrida M Uys
- US/MRC Centre for Molecular and Cellular Biology, Department of Biomedical Sciences, University of Stellenbosch, South Africa
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Christian F, Szaszák M, Friedl S, Drewianka S, Lorenz D, Goncalves A, Furkert J, Vargas C, Schmieder P, Götz F, Zühlke K, Moutty M, Göttert H, Joshi M, Reif B, Haase H, Morano I, Grossmann S, Klukovits A, Verli J, Gáspár R, Noack C, Bergmann M, Kass R, Hampel K, Kashin D, Genieser HG, Herberg FW, Willoughby D, Cooper DMF, Baillie GS, Houslay MD, von Kries JP, Zimmermann B, Rosenthal W, Klussmann E. Small molecule AKAP-protein kinase A (PKA) interaction disruptors that activate PKA interfere with compartmentalized cAMP signaling in cardiac myocytes. J Biol Chem 2011; 286:9079-96. [PMID: 21177871 PMCID: PMC3058960 DOI: 10.1074/jbc.m110.160614] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 12/12/2010] [Indexed: 12/22/2022] Open
Abstract
A-kinase anchoring proteins (AKAPs) tether protein kinase A (PKA) and other signaling proteins to defined intracellular sites, thereby establishing compartmentalized cAMP signaling. AKAP-PKA interactions play key roles in various cellular processes, including the regulation of cardiac myocyte contractility. We discovered small molecules, 3,3'-diamino-4,4'-dihydroxydiphenylmethane (FMP-API-1) and its derivatives, which inhibit AKAP-PKA interactions in vitro and in cultured cardiac myocytes. The molecules bind to an allosteric site of regulatory subunits of PKA identifying a hitherto unrecognized region that controls AKAP-PKA interactions. FMP-API-1 also activates PKA. The net effect of FMP-API-1 is a selective interference with compartmentalized cAMP signaling. In cardiac myocytes, FMP-API-1 reveals a novel mechanism involved in terminating β-adrenoreceptor-induced cAMP synthesis. In addition, FMP-API-1 leads to an increase in contractility of cultured rat cardiac myocytes and intact hearts. Thus, FMP-API-1 represents not only a novel means to study compartmentalized cAMP/PKA signaling but, due to its effects on cardiac myocytes and intact hearts, provides the basis for a new concept in the treatment of chronic heart failure.
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Affiliation(s)
- Frank Christian
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Márta Szaszák
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Sabine Friedl
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Stephan Drewianka
- Biaffin GmbH & Co. KG, AVZ 2, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany
| | - Dorothea Lorenz
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Andrey Goncalves
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Jens Furkert
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Carolyn Vargas
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Peter Schmieder
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Frank Götz
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Kerstin Zühlke
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Marie Moutty
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Hendrikje Göttert
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Mangesh Joshi
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Bernd Reif
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Hannelore Haase
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Ingo Morano
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Solveig Grossmann
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Anna Klukovits
- the Department of Pharmacodynamics and Biopharmacy, University of Szeged, H-6720 Szeged, Eötvös u. 6., Hungary
| | - Judit Verli
- the Department of Pharmacodynamics and Biopharmacy, University of Szeged, H-6720 Szeged, Eötvös u. 6., Hungary
| | - Róbert Gáspár
- the Department of Pharmacodynamics and Biopharmacy, University of Szeged, H-6720 Szeged, Eötvös u. 6., Hungary
| | - Claudia Noack
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Martin Bergmann
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Robert Kass
- Columbia University Medical Center, New York, New York 10032
| | - Kornelia Hampel
- Biaffin GmbH & Co. KG, AVZ 2, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany
| | - Dmitry Kashin
- Biolog Life Science Institute, Flughafendamm 9A, 28199 Bremen, Germany
| | | | - Friedrich W. Herberg
- the Department of Biochemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34109 Kassel, Germany
| | - Debbie Willoughby
- the Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1 PD, United Kingdom
| | - Dermot M. F. Cooper
- the Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1 PD, United Kingdom
| | - George S. Baillie
- Neuroscience and Molecular Pharmacology, Wolfson Link and Davidson Buildings, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom, and
| | - Miles D. Houslay
- Neuroscience and Molecular Pharmacology, Wolfson Link and Davidson Buildings, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom, and
| | - Jens Peter von Kries
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Bastian Zimmermann
- Biaffin GmbH & Co. KG, AVZ 2, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany
| | - Walter Rosenthal
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Molecular Pharmacology and Cell Biology, Charité-University Medicine Berlin, Thielallee 73, 14195 Berlin, Germany
| | - Enno Klussmann
- From the Leibniz Institute for Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
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Wu Y, Yin X, Wijaya C, Huang MH, McConnell BK. Acute myocardial infarction in rats. J Vis Exp 2011:2464. [PMID: 21372786 DOI: 10.3791/2464] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
With heart failure leading the cause of death in the USA (Hunt), biomedical research is fundamental to advance medical treatments for cardiovascular diseases. Animal models that mimic human cardiac disease, such as myocardial infarction (MI) and ischemia-reperfusion (IR) that induces heart failure as well as pressure-overload (transverse aortic constriction) that induces cardiac hypertrophy and heart failure (Goldman and Tarnavski), are useful models to study cardiovascular disease. In particular, myocardial ischemia (MI) is a leading cause for cardiovascular morbidity and mortality despite controlling certain risk factors such as arteriosclerosis and treatments via surgical intervention (Thygesen). Furthermore, an acute loss of the myocardium following myocardial ischemia (MI) results in increased loading conditions that induces ventricular remodeling of the infarcted border zone and the remote non-infarcted myocardium. Myocyte apoptosis, necrosis and the resultant increased hemodynamic load activate multiple biochemical intracellular signaling that initiates LV dilatation, hypertrophy, ventricular shape distortion, and collagen scar formation. This pathological remodeling and failure to normalize the increased wall stresses results in progressive dilatation, recruitment of the border zone myocardium into the scar, and eventually deterioration in myocardial contractile function (i.e. heart failure). The progression of LV dysfunction and heart failure in rats is similar to that observed in patients who sustain a large myocardial infarction, survive and subsequently develops heart failure (Goldman). The acute myocardial infarction (AMI) model in rats has been used to mimic human cardiovascular disease; specifically used to study cardiac signaling mechanisms associated with heart failure as well as to assess the contribution of therapeutic strategies for the treatment of heart failure. The method described in this report is the rat model of acute myocardial infarction (AMI). This model is also referred to as an acute ischemic cardiomyopathy or ischemia followed by reperfusion (IR); which is induced by an acute 30-minute period of ischemia by ligation of the left anterior descending artery (LAD) followed by reperfusion of the tissue by releasing the LAD ligation (Vasilyev and McConnell). This protocol will focus on assessment of the infarct size and the area-at-risk (AAR) by Evan's blue dye and triphenyl tetrazolium chloride (TTC) following 4-hours of reperfusion; additional comments toward the evaluation of cardiac function and remodeling by modifying the duration of reperfusion, is also presented. Overall, this AMI rat animal model is useful for studying the consequence of a myocardial infarction on cardiac pathophysiological and physiological function.
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Affiliation(s)
- Yewen Wu
- Department of Internal Medicine, Division of Cardiology, University of Texas Medical Branch, USA
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50
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Sumandea CA, Garcia-Cazarin ML, Bozio CH, Sievert GA, Balke CW, Sumandea MP. Cardiac troponin T, a sarcomeric AKAP, tethers protein kinase A at the myofilaments. J Biol Chem 2010; 286:530-41. [PMID: 21056973 DOI: 10.1074/jbc.m110.148684] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Efficient and specific phosphorylation of PKA substrates, elicited in response to β-adrenergic stimulation, require spatially confined pools of PKA anchored in proximity of its substrates. PKA-dependent phosphorylation of cardiac sarcomeric proteins has been the subject of intense investigations. Yet, the identity, composition, and function of PKA complexes at the sarcomeres have remained elusive. Here we report the identification and characterization of a novel sarcomeric AKAP (A-kinase anchoring protein), cardiac troponin T (cTnT). Using yeast two-hybrid technology in screening two adult human heart cDNA libraries, we identified the regulatory subunit of PKA as interacting with human cTnT bait. Immunoprecipitation studies show that cTnT is a dual specificity AKAP, interacting with both PKA-regulatory subunits type I and II. The disruptor peptide Ht31, but not Ht31P (control), abolished cTnT/PKA-R association. Truncations and point mutations identified an amphipathic helix domain in cTnT as the PKA binding site. This was confirmed by a peptide SPOT assay in the presence of Ht31 or Ht31P (control). Gelsolin-dependent removal of thin filament proteins also reduced myofilament-bound PKA-type II. Using a cTn exchange procedure that substitutes the endogenous cTn complex with a recombinant cTn complex we show that PKA-type II is troponin-bound in the myofilament lattice. Displacement of PKA-cTnT complexes correlates with a significant decrease in myofibrillar PKA activity. Taken together, our data propose a novel role for cTnT as a dual-specificity sarcomeric AKAP.
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Affiliation(s)
- C Amelia Sumandea
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, Kentucky 40536, USA
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