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Wegener JW, Mitronova GY, ElShareif L, Quentin C, Belov V, Pochechueva T, Hasenfuss G, Ackermann L, Lehnart SE. A dual-targeted drug inhibits cardiac ryanodine receptor Ca 2+ leak but activates SERCA2a Ca 2+ uptake. Life Sci Alliance 2024; 7:e202302278. [PMID: 38012000 PMCID: PMC10681910 DOI: 10.26508/lsa.202302278] [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: 07/17/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 11/29/2023] Open
Abstract
In the heart, genetic or acquired mishandling of diastolic [Ca2+] by ryanodine receptor type 2 (RyR2) overactivity correlates with risks of arrhythmia and sudden cardiac death. Strategies to avoid these risks include decrease of Ca2+ release by drugs modulating RyR2 activity or increase in Ca2+ uptake by drugs modulating SR Ca2+ ATPase (SERCA2a) activity. Here, we combine these strategies by developing experimental compounds that act simultaneously on both processes. Our screening efforts identified the new 1,4-benzothiazepine derivative GM1869 as a promising compound. Consequently, we comparatively studied the effects of the known RyR2 modulators Dantrolene and S36 together with GM1869 on RyR2 and SERCA2a activity in cardiomyocytes from wild type and arrhythmia-susceptible RyR2R2474S/+ mice by confocal live-cell imaging. All drugs reduced RyR2-mediated Ca2+ spark frequency but only GM1869 accelerated SERCA2a-mediated decay of Ca2+ transients in murine and human cardiomyocytes. Our data indicate that S36 and GM1869 are more suitable than dantrolene to directly modulate RyR2 activity, especially in RyR2R2474S/+ mice. Remarkably, GM1869 may represent a new dual-acting lead compound for maintenance of diastolic [Ca2+].
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Affiliation(s)
- Jörg W Wegener
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Gyuzel Y Mitronova
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Lina ElShareif
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
| | - Christine Quentin
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Vladimir Belov
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Tatiana Pochechueva
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Gerd Hasenfuss
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Lutz Ackermann
- Georg-August University of Göttingen, Institute of Organic and Biomolecular Chemistry, Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Stephan E Lehnart
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center of Göttingen (UMG), Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
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Ye J, Zheng Q, Jia S, Qiao X, Cao Y, Xu C, Weng L, Zhao L, Chen Y, Liu J, Wang T, Cheng H, Zheng M. Programmed Cell Death 5 Provides Negative Feedback on Cardiac Hypertrophy Through the Stabilization of Sarco/Endoplasmic Reticulum Ca 2+-ATPase 2a Protein. Hypertension 2019; 72:889-901. [PMID: 30354711 DOI: 10.1161/hypertensionaha.118.11357] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
PDCD5 (programmed cell death 5) is ubiquitously expressed in tissues, including the heart; however, the mechanism underlying the cardiac function of PDCD5 has not been understood. We investigated the mechanisms of PDCD5 in the pathogenesis of cardiac hypertrophy. Cardiac-specific PDCD5 knockout mice developed severe cardiac hypertrophy and impaired cardiac function, whereas PDCD5 protein was significantly increased in transverse aortic constriction mouse hearts and phenylephrine-stimulated cardiomyocytes. Overexpression of PDCD5 inhibited phenylephrine-induced cardiomyocyte hypertrophy, and knockdown of PDCD5 induced cardiomyocyte hypertrophy and aggravated phenylephrine-induced hypertrophy. The expression of PDCD5 protein was regulated by NFATc2 (nuclear factor of activated T cells c2) during hypertrophy. SERCA2a (sarco/endoplasmic reticulum Ca2+-ATPase 2a) expression was decreased in PDCD5-deficient mouse hearts because of increased ubiquitination. PDCD5-deficient cardiomyocytes displayed decreased calcium uptake rate, slowed decay of Ca2+ transients, decreased calcium stores, and diastolic dysfunction. Moreover, reintroduction of PDCD5 in PDCD5-deficient mouse hearts reserved SERCA2a protein, suppressed NFATc2 protein, and rescued the hypertrophy and cardiac dysfunction. Our results revealed that PDCD5 is a novel target of NFATc2 in the hypertrophic heart and provides negative feedback to protect the heart against excessive hypertrophy via the stabilization of SERCA2a protein.
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Affiliation(s)
- Jingjing Ye
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
| | - Qiaoxia Zheng
- Institute of Molecular Medicine, Peking University, Beijing, P.R. China (Q.Z., H.C.)
| | - Shi Jia
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
| | - Xue Qiao
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
| | - Yangpo Cao
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
| | - Chunling Xu
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
| | - Lin Weng
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
| | - Lifang Zhao
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
| | - Yingyu Chen
- Key Laboratory of Medical Immunology, Ministry of Health (Y.C.), Peking University Health Science Center, Beijing, China
| | - Jian Liu
- Departments of Cardiology (J.L.), Peking University People's Hospital, Beijing, China
| | - Tianbing Wang
- Trauma and Orthopedics (T.W.), Peking University People's Hospital, Beijing, China
| | - Heping Cheng
- Institute of Molecular Medicine, Peking University, Beijing, P.R. China (Q.Z., H.C.)
| | - Ming Zheng
- From the Department of Physiology and Pathophysiology, School of Basic Medical Sciences (J.Y., S.J., X.Q., Y.C., C.X., L.W., L.Z., M.Z.), Peking University Health Science Center, Beijing, China
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Park KC, Kim SW, Jeon JY, Jo AR, Choi HJ, Kim J, Lee HG, Kim Y, Mills GB, Noh SH, Lee MG, Park ES, Cheong JH. Survival of Cancer Stem-Like Cells Under Metabolic Stress via CaMK2α-mediated Upregulation of Sarco/Endoplasmic Reticulum Calcium ATPase Expression. Clin Cancer Res 2017; 24:1677-1690. [DOI: 10.1158/1078-0432.ccr-17-2219] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/24/2017] [Accepted: 12/20/2017] [Indexed: 11/16/2022]
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Bouyon S, Roussel V, Fromes Y. SERCA2a gene therapy can improve symptomatic heart failure in δ-sarcoglycan-deficient animals. Hum Gene Ther 2014; 25:694-704. [PMID: 24645914 PMCID: PMC4137356 DOI: 10.1089/hum.2013.132] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 03/18/2014] [Indexed: 11/13/2022] Open
Abstract
The loss of dystrophin or its associated proteins results in the development of muscle wasting frequently associated with cardiomyopathy. Contractile cardiac tissue is injured and replaced by fibrous tissue or fatty infiltrates, leading to a progressive decrease of the contractile force and finally to end-stage heart failure. At the time symptoms appear, restoration of a functional allele of the causative gene might not be sufficient to prevent disease progression. Alterations in Ca(2+) transport and intracellular calcium levels have been implicated in many types of pathological processes, especially in heart disease. On the basis of a gene transfer strategy, we analyzed the therapeutic efficacy of primary gene correction in a δ-sarcoglycan (δ-SG)-deficient animal model versus gene transfer of the Ca(2+) pump hSERCA2a (human sarco-endoplasmic reticulum calcium ATPase 2a), at a symptomatic stage of heart disease. Our results strongly suggest that restoration of δ-SG at this stage of disease will not lead to improved clinical outcome. However, restoration of proper Ca(2+) handling by means of amplifying SERCA2a expression in the myocardium can lead to functional improvement. Abnormalities in Ca(2+) handling play an important role in disease progression toward heart failure, and increased SERCA2a levels appear to significantly improve cardiac contraction and relaxation. Beneficial effects persist at least over a period of 6 months, and the evolution of cardiac functional parameters paralleled those of normal controls. Furthermore, we demonstrate that a plasmid formulation based on amphiphilic block copolymers can provide a safe and efficient platform for myocardial gene therapies. The use of synthetic formulations for myocardial gene transfer might thus overcome one of the major hurdles linked to viral vectors, that is, repeat administrations.
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Affiliation(s)
- Sophie Bouyon
- UPMC um76, INSERM u974, CNRS umr7215, Institut de Myologie, 75013 Paris, France
| | - Véronique Roussel
- UPMC um76, INSERM u974, CNRS umr7215, Institut de Myologie, 75013 Paris, France
| | - Yves Fromes
- UPMC um76, INSERM u974, CNRS umr7215, Institut de Myologie, 75013 Paris, France
- ONIRIS, Centre de Boisbonne, 44307 Nantes, France
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Muller A, Simonides WS. Regulation of myocardial SERCA2a expression in ventricular hypertrophy and heart failure. Future Cardiol 2009; 1:543-53. [PMID: 19804155 DOI: 10.2217/14796678.1.4.543] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Diminished contractility of the hypertrophic cardiomyocyte is a principal determinant of ventricular dysfunction in chronic heart failure. Reduction of activity of the sarcoplasmic/endoplasmic reticulum calcium ion (Ca2+)-ATPase (SERCA2a), underlies many of the effects of overload-induced hypertrophy on cardiomyocyte performance, and it may be critical in the progression of compensatory hypertrophy to heart failure. This review shall focus on the transcriptional regulation of SERCA2a expression as the primary cause of decreased SERCA2a activity in heart failure. Furthermore, the relevance for SERCA2a expression of signal transduction routes involved in pathologic hypertrophy and the possible therapeutic implications, shall be addressed.
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Affiliation(s)
- Alice Muller
- Institute for Cardiovascular Research, Laboratory for Physiology, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
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Zarain-Herzberg A. Regulation of the sarcoplasmic reticulum Ca2+-ATPase expression in the hypertrophic and failing heartThis paper is part of a series in the Journal's “Made in Canada” section. The paper has undergone peer review. Can J Physiol Pharmacol 2006; 84:509-21. [PMID: 16902596 DOI: 10.1139/y06-023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The sarcoplasmic reticulum (SR) plays a central role in the contraction and relaxation coupling in the myocardium. The SR Ca2+-ATPase (SERCA2) transports Ca2+ inside the SR lumen during relaxation of the cardiac myocyte. It is well known that diminished contractility of the hypertrophic cardiac myocyte is the main factor of ventricular dysfunction in the failing heart. A key feature of the failing heart is a decreased content and activity of SERCA2, which is the cause of some of the physiological defects observed in the hypertrophic cardiomyocyte performance that are important during transition of compensated hypertrophy to heart failure. In this review different possible mechanisms responsible for decreased transcriptional regulation of the SERCA2 gene are examined, which appear to be the primary cause for decreased SERCA2 expression in heart failure. The experimental evidence suggests that several signalling pathways are involved in the downregulation of SERCA2 expression in the hypertrophic and failing cardiomyocyte. Therapeutic upregulation of SERCA2 expression using replication deficient adenoviral expression vectors, pharmacological interventions using thyroid hormone analogues, β-adrenergic receptor antagonists, and novel metabolically active compounds are currently under investigation for the treatment of uncompensated cardiac hypertrophy and heart failure.
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Affiliation(s)
- Angel Zarain-Herzberg
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, México D.F, 04510.
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Blum JL, Samarel AM, Mestril R. Phosphorylation and binding of AUF1 to the 3'-untranslated region of cardiomyocyte SERCA2a mRNA. Am J Physiol Heart Circ Physiol 2005; 289:H2543-50. [PMID: 16113063 DOI: 10.1152/ajpheart.00545.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Experimental animals and patients with cardiac hypertrophy and heart failure display abnormally slowed myocardial relaxation, which is associated with downregulation of sarco(endo)plasmic reticulum calcium ATPase 2a (SERCA2a), the cardiomyocyte sarcoplasmic reticulum Ca2+ pump. We previously showed that SERCA2a downregulation can be simulated in cultured neonatal rat ventricular myocytes (NRVM) by treatment with the hypertrophic agonist phorbol myristate acetate (PMA) or by overexpression of the novel protein kinase C (PKC) isoenzymes PKCdelta and PKCepsilon. PKC activation, in turn, decreased SERCA2a promoter activity and destabilized the SERCA2a mRNA. Here we demonstrate by using an RSV beta-galactosidase reporter system that a 609-nt fragment of the SERCA2a mRNA 3'-untranslated region (UTR), containing five adenylate-uridylate (AU)-rich regions, may be responsible for destabilizing the message following PMA treatment. UV cross-linking analysis demonstrated that several proteins found in the NRVM cell extracts bind to the 609-nt fragment. In addition, protein binding was transiently increased in response to PMA stimulation. 3'-UTR mRNA pull-down assays and Western blot analysis indicated that the AU binding protein AUF1 interacted with the SERCA2a 3'-UTR. AUF1 binding activity was predominantly found in the nuclear fraction, and PMA-induced AUF1 binding was associated with increased threonine phosphorylation of AUF1. These data suggest that the phosphorylation, binding, and location of AUF1 affect the posttranscriptional regulation of the SERCA2a message in NRVM.
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Affiliation(s)
- Juliana L Blum
- The Cardiovascular Institute, Loyola Univ. Medical Center, Bldg 110, Rm. 5222, 2160 South First Ave., Maywood, IL 60153, USA
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Heidkamp MC, Scully BT, Vijayan K, Engman SJ, Szotek EL, Samarel AM. PYK2 regulates SERCA2 gene expression in neonatal rat ventricular myocytes. Am J Physiol Cell Physiol 2005; 289:C471-82. [PMID: 15829561 DOI: 10.1152/ajpcell.00130.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nonreceptor protein tyrosine kinase (PTK) proline-rich tyrosine kinase 2 (PYK2) has been implicated in cell signaling pathways involved in left ventricular hypertrophy and heart failure, but its exact role has not been elucidated. In this study, replication-defective adenoviruses (Adv) encoding green fluorescent protein (GFP)-tagged, wild-type (WT), and mutant forms of PYK2 were used to determine whether PYK2 overexpression activates MAPKs, and downregulates SERCA2 mRNA levels in neonatal rat ventricular myocytes (NRVM). PYK2 overexpression significantly decreased SERCA2 mRNA (as determined by Northern blot analysis and real-time RT-PCR) to 54 ± 4% of Adv-GFP-infected cells 48 h after Adv infection. Adv-encoding kinase-deficient (KD) and Y402F phosphorylation-deficient mutants of PYK2 also significantly reduced SERCA2 mRNA (WT>KD>Y402F). Conversely, the PTK inhibitor PP2 (which blocks PYK2 phosphorylation by Src-family PTKs) significantly increased SERCA2 mRNA levels. PYK2 overexpression had no effect on ERK1/2, but increased JNK1/2 and p38MAPKphosphorylation from fourfold to eightfold compared with GFP overexpression. Activation of both “stress-activated” protein kinase cascades appeared necessary to reduce SERCA2 mRNA levels. Adv-mediated overexpression of constitutively active (ca)MKK6 or caMKK7, which activated only p38MAPKor JNKs, respectively, was not sufficient, whereas combined infection with both Adv reduced SERCA2 mRNA levels to 45 ± 12% of control. WTPYK2 overexpression also significantly reduced SERCA2 promoter activity, as determined by transient transfection of a 3.8-kb SERCA2 promoter-luciferase construct. Thus a PYK2-dependent signaling cascade may have a role in abnormal cardiac Ca2+handling in left ventricular hypertrophy and heart failure via downregulation of SERCA2 gene transcription.
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Affiliation(s)
- Maria C Heidkamp
- The Cardiovascular Institute, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
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Gupta RC, Yang XP, Mishra S, Sabbah HN. Assessment of sarcoplasmic reticulum Ca2+-uptake during the development of left ventricular hypertrophy. Biochem Pharmacol 2003; 65:933-9. [PMID: 12623124 DOI: 10.1016/s0006-2952(02)01625-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac sarcoplasmic reticulum (SR) sequesters Ca(2+) and plays a crucial role in the regulation of intracellular Ca(2+). Its functional properties are central to the excitation-contraction cycle of cardiac muscle. In this study, we hypothesized that alterations in SR function occur during the development of left ventricular (LV) hypertrophy. LV hypertrophy was produced in Lewis rats by the one-kidney, one-clip (1K1C) procedure. LV tissues were obtained from 1K1C rats 1 week (mild, N=7), 4 weeks (moderate, N=7), and 8 weeks (severe, N=7) post-surgery and from the corresponding age-matched, sham-operated controls (N=7 at each stage). In all of these rats, the ratio of LV weight (g) to body weight (kg) was determined and considered as an index for LV hypertrophy. In addition, the ratio of lung weight (g) to body weight (kg) was determined and considered as an index for pulmonary congestion and heart failure. In each LV specimen, SR Ca(2+)-uptake and tissue Ca(2+)-ATPase (CAA) level were determined. In 1K1C rats, LV hypertrophy increased by 21, 40, and 90% at 1, 4, and 8 weeks post-surgery, respectively, compared to the age-matched, sham-operated rats, whereas pulmonary congestion did not occur at 1 and 4 weeks but increased significantly by about 21% at 8 weeks. Further, both SR Ca(2+)-uptake and immunodetectable CAA level did not change at 1 week, increased (54%) to the same extent at 4 weeks, and decreased (42%) by approximately the same extent at 8 weeks in 1K1C rats compared to the age-matched, sham-operated rats. In summary, as LV hypertrophy evolved, Ca(2+)-uptake and CAA expression did not change in the early, increased in the moderate, and then declined in the later stages of hypertrophy development. The increase in Ca(2+)-uptake and CAA expression suggests, at the cellular level, a compensatory response to LV hypertrophy, while the decline at later stages indicates the transition to heart failure.
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Affiliation(s)
- Ramesh C Gupta
- Cardiovascular Medicine Division, Department of Medicine, Henry Ford Heart and Vascular Institute, Henry Ford Health System, 2799 West Grand Boulevard, Detroit, MI 48202, USA.
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Drug Development Based on Functional Genomics of Overloaded Cardiomyocytes: CPT 1 vs. PPARalpha Effects of Etomoxir. PROGRESS IN EXPERIMENTAL CARDIOLOGY 2003. [DOI: 10.1007/978-1-4615-0455-9_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Zarain-Herzberg A, Rupp H. Therapeutic potential of CPT I inhibitors: cardiac gene transcription as a target. Expert Opin Investig Drugs 2002; 11:345-56. [PMID: 11866664 DOI: 10.1517/13543784.11.3.345] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Inhibitors of carnitine palmitoyl-transferase I (CPT I), the key enzyme for the transport of long-chain acyl-coenzyme A (acyl-CoA) compounds into mitochondria, have been developed as agents for treating diabetes mellitus Type 2. Findings that the CPT I inhibitor, etomoxir, has effects on overloaded heart muscle, which are associated with an improved function, were unexpected and can be attributed to selective changes in the dysregulated gene expression of hypertrophied cardiomyocytes. Also, the first clinical trial with etomoxir in patients with heart failure showed that etomoxir improved the clinical status and several parameters of heart function. In view of the action of etomoxir on gene expression, putative molecular mechanisms involved in an increased expression of SERCA2, the Ca(2+) pump of sarcoplasmic reticulum (SR) and alpha-myosin heavy chain (MHC) of failing overloaded heart muscle are described. The first 225 bp of human, rabbit, rat and mouse SERCA2 promoter sequence have high identity. Various cis-regularory elements are also given for the promoter of the rat cardiac alpha-MHC gene. It is hypothesised that etomoxir increases glucose-phosphate intermediates resulting in activation of signalling pathway(s) mediated by phosphatases. Regarding the possible direct action of etomoxir on peroxisome proliferator activated receptor alpha (PPAR-alpha) activation, it could upregulate the expression of various enzymes that participate in beta-oxidation, thereby modulating some effects of CPT 1 inhibition. Any development of alternative drugs requires a better understanding of the signal pathways involved in the altered gene expression. In particular, signals need to be identified which are altered in overloaded hearts and can selectively be re-activated by etomoxir.
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Affiliation(s)
- Angel Zarain-Herzberg
- Laboratorio de Biología Molecular, Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, México D.F. 04510.
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Takizawa T, Arai M, Yoguchi A, Tomaru K, Kurabayashi M, Nagai R. Transcription of the SERCA2 gene is decreased in pressure-overloaded hearts: A study using in vivo direct gene transfer into living myocardium. J Mol Cell Cardiol 1999; 31:2167-74. [PMID: 10640444 DOI: 10.1006/jmcc.1999.1045] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
T. Takizawa, M. Arai, A. Yoguchi, K. Tomaru, M. Kurabayashi and R. Nagai. Transcription of the SERCA2 Gene is Decreased in Pressure-overloaded Hearts: A Study Using In Vivo Direct Gene Transfer into Living Myocardium. Journal of Molecular and Cellular Cardiology (1999) 31, 2167-2174. The sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2) controls the myocardial relaxation process. Under pressure-overload, the expression of its mRNA decreases, thus controlling cardiac function to conform to the load. However, it is not known whether this decreased expression is caused by a decrease in the transcription of the SERCA2 gene. The object of this study was to determine the transcription control mechanism of the SERCA2 gene under pressure-overload in vivo, and to identify the pressure-overload-sensitive regions of the SERCA2 gene. Ten micrograms of a plasmid, containing the 5' upstream (-1810 bp to +350 bp) region of the SERCA2 gene and a luciferase reporter gene, were introduced into adult rat myocardium by in vivo direct gene transfer, and the luciferase activity was measured 5 days later. The transcriptional activity under pressure-overload decreased to 27+/-17% of the control. Based on this result, we concluded that the decreased mRNA expression of SERCA2 in pressure-overload cardiac hypertrophy is due to decreased gene transcription. In addition, various deletion fragments of the SERCA2 promoter region were produced, and tested for luciferase production under pressure-overload. Our data suggest that a transcription activation site is present between -685 and -284 bp, and two transcription inhibition sites are present between -1810 to -1110 bp and -284 to -72 bp. These may be the pressure-sensitive regions of the SERCA2 gene of in vivo hypertrophied myocardium under pressure-overload.
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Affiliation(s)
- T Takizawa
- Second Department of Internal Medicine, Gunma University School of Medicine, Gunma, Japan
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Abstract
The transition of nonfailing to failing cardiac hypertrophy cannot be prevented by current drug regimens. This investigation examined whether possible drug targets have remained unexplored because they do not result in acute improvement of heart function. Of major importance, in this respect, is an inadequate performance of the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2). In the present approach, binding sequences within the proximal promoter of SERCA2 are described which may be useful in the development of drugs (i.e., transcriptional modulators) that interfere selectively with the transcription of genes of the cardiomyocyte. The proximal promoter region of the SERCA2 genes has a thyroid response element, 9 potential Sp1-binding sites (5'-GGGCGG-3', 5'-CCGCCC-3' and 5'-GGGAGG-3'), and an E-box motif (5'-CACATG-3'), which may function as glucose response elements. This region also has 2 putative fatty-acid response elements (5'-GGGGGA-3'). It is proposed that the beneficial effects of the camitine palmitoyltransferase-1 inhibitor etomoxir arise from a shift in fuel metabolism involving glucose response elements and/or peroxisomal proliferator-activated receptors. Although the relative contribution of these DNA regulatory elements remains to be defined, it appears that they provide the driving force that prevents the decrease in transcriptional activity of the SERCA2 gene in the hypertrophic heart. It is further concluded that etomoxir represents a member of a novel class of transcriptional modulators that improve function of hypertrophied hearts with unimpeded blood flow by modulating gene expression of the cardiomyocyte.
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Affiliation(s)
- A Zarain-Herzberg
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City
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