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Chen Q, Thompson J, Hu Y, Lesnefsky EJ. Aging-induced mitochondrial dysfunction: two distinct populations of mitochondria versus a combined population. Am J Physiol Heart Circ Physiol 2024; 326:H385-H395. [PMID: 38099846 PMCID: PMC11219051 DOI: 10.1152/ajpheart.00363.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/17/2023] [Accepted: 11/29/2023] [Indexed: 01/14/2024]
Abstract
Mitochondrial function in aged hearts is impaired, and studies of isolated mitochondria are commonly used to assess their function. The two populations of cardiac mitochondria, subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM), are affected by aging. However, the yield of these mitochondria, particularly SSM, is limited in the mouse heart because of the smaller heart size. To address this issue, the authors developed a method to isolate a mixed population (MIX) of SSM and IFM mitochondria from a single mouse heart. The aim of the study was to compare the mitochondrial function between SSM, IFM, and the MIX population from young and aged mouse hearts. The MIX population had a higher yield of total protein and citrate synthase activity from both young and aged hearts compared with the individual yields of SSM or IFM. Oxidative phosphorylation (OXPHOS) decreased in aged SSM and IFM compared with young SSM and IFM, as well as in the MIX population isolated from aged hearts compared with young hearts, when using complex I or IV substrates. Furthermore, aging barely affected the sensitivity to mitochondrial permeability transition pore (MPTP) opening in SSM, whereas the sensitivity was increased in IFM isolated from aged hearts and in the MIX population from aged hearts compared with the corresponding populations isolated from young hearts. These results suggest that mitochondrial dysfunction exists in aged hearts and the isolation of a MIX population of mitochondria from the mouse heart is a potential approach to studying mitochondrial function in the mouse heart.NEW & NOTEWORTHY We developed two methods to isolate mitochondria from a single mouse heart. We compared mitochondrial function in young and aged mice using mitochondria isolated with different methods. Both methods can be successfully used to isolate cardiac mitochondria from single mouse hearts. Our results provide the flexibility to isolate mitochondria from a single mouse heart based on the purpose of the study.
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Affiliation(s)
- Qun Chen
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia, United States
| | - Jeremy Thompson
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia, United States
| | - Ying Hu
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia, United States
| | - Edward J Lesnefsky
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia, United States
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia, United States
- Department of Veterans Affairs Medical Center, Richmond, Virginia, United States
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2
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Chen Q, Thompson J, Hu Y, Lesnefsky EJ. Endoplasmic reticulum stress and alterations of peroxiredoxins in aged hearts. Mech Ageing Dev 2023; 215:111859. [PMID: 37661065 PMCID: PMC11103240 DOI: 10.1016/j.mad.2023.111859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/20/2023] [Accepted: 08/29/2023] [Indexed: 09/05/2023]
Abstract
Aging-related cardiovascular disease is influenced by multiple factors, with oxidative stress being a key contributor. Aging-induced endoplasmic reticulum (ER) stress exacerbates oxidative stress by impairing mitochondrial function. Furthermore, a decline in antioxidants, including peroxiredoxins (PRDXs), augments the oxidative stress during aging. To explore if ER stress leads to PRDX degradation during aging, young adult (3 mo.) and aged (24 mo.) male mice were studied. Treatment with 4-phenylbutyrate (4-PBA) was used to alleviate ER stress in young adult and aged mice. Aged hearts showed elevated oxidative stress levels compared to young hearts. However, treatment with 4-PBA to attenuate ER stress reduced oxidative stress in aged hearts, indicating that ER stress contributes to increased oxidative stress in aging. Moreover, aging resulted in reduced levels of peroxiredoxin 3 (PRDX3) in mitochondria and peroxiredoxin 4 (PRDX4) in myocardium. While 4-PBA treatment improved PRDX3 content in aged hearts, it did not restore PRDX4 content in aged mice. These findings suggest that ER stress not only leads to mitochondrial dysfunction and increased oxidant stress but also impairs a vital antioxidant defense through decreased PRDX3 content. Additionally, the results suggest that PRDX4 may contribute an upstream role in inducing ER stress during aging.
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Affiliation(s)
- Qun Chen
- Departments of Medicine (Division of Cardiology), Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Jeremy Thompson
- Departments of Medicine (Division of Cardiology), Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Ying Hu
- Departments of Medicine (Division of Cardiology), Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Edward J Lesnefsky
- Departments of Medicine (Division of Cardiology), Virginia Commonwealth University, Richmond, VA 23298, USA; Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA; Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298, USA; Richmond Department of Veterans Affairs Medical Center, Richmond, VA 23249, USA.
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3
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Chen Q, Thompson J, Hu Y, Lesnefsky EJ. Reversing mitochondrial defects in aged hearts: role of mitochondrial calpain activation. Am J Physiol Cell Physiol 2022; 322:C296-C310. [PMID: 35044856 PMCID: PMC8836732 DOI: 10.1152/ajpcell.00279.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/10/2022] [Accepted: 01/10/2022] [Indexed: 02/03/2023]
Abstract
Aging chronically increases endoplasmic reticulum (ER) stress that contributes to mitochondrial dysfunction. Activation of calpain 1 (CPN1) impairs mitochondrial function during acute ER stress. We proposed that aging-induced ER stress led to mitochondrial dysfunction by activating CPN1. We posit that attenuation of the ER stress or direct inhibition of CPN1 in aged hearts can decrease cardiac injury during ischemia-reperfusion by improving mitochondrial function. Male young (3 mo) and aged mice (24 mo) were used in the present study, and 4-phenylbutyrate (4-PBA) was used to decrease the ER stress in aged mice. Subsarcolemmal (SSM) and interfibrillar mitochondria (IFM) were isolated. Chronic 4-PBA treatment for 2 wk decreased CPN1 activation as shown by the decreased cleavage of spectrin in cytosol and apoptosis inducing factor (AIF) and the α1 subunit of pyruvate dehydrogenase (PDH) in mitochondria. Treatment improved oxidative phosphorylation in 24-mo-old SSM and IFM at baseline compared with vehicle. When 4-PBA-treated 24-mo-old hearts were subjected to ischemia-reperfusion, infarct size was decreased. These results support that attenuation of the ER stress decreased cardiac injury in aged hearts by improving mitochondrial function before ischemia. To challenge the role of CPN1 as an effector of the ER stress, aged mice were treated with MDL-28170 (MDL, an inhibitor of calpain 1). MDL treatment improved mitochondrial function in aged SSM and IFM. MDL-treated 24-mo-old hearts sustained less cardiac injury following ischemia-reperfusion. These results support that age-induced ER stress augments cardiac injury during ischemia-reperfusion by impairing mitochondrial function through activation of CPN1.
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Affiliation(s)
- Qun Chen
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Jeremy Thompson
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Ying Hu
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Edward J Lesnefsky
- Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
- McGuire Department of Veterans Affairs Medical Center, Richmond, Virginia
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4
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Díaz-Vesga MC, Zúñiga-Cuevas Ú, Ramírez-Reyes A, Herrera-Zelada N, Palomo I, Bravo-Sagua R, Riquelme JA. Potential Therapies to Protect the Aging Heart Against Ischemia/Reperfusion Injury. Front Cardiovasc Med 2021; 8:770421. [PMID: 34869687 PMCID: PMC8639870 DOI: 10.3389/fcvm.2021.770421] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/29/2021] [Indexed: 12/11/2022] Open
Abstract
Despite important advances in the treatment of myocardial infarction that have significantly reduced mortality, there is still an unmet need to limit the infarct size after reperfusion injury in order to prevent the onset and severity of heart failure. Multiple cardioprotective maneuvers, therapeutic targets, peptides and drugs have been developed to effectively protect the myocardium from reperfusion-induced cell death in preclinical studies. Nonetheless, the translation of these therapies from laboratory to clinical contexts has been quite challenging. Comorbidities, comedications or inadequate ischemia/reperfusion experimental models are clearly identified variables that need to be accounted for in order to achieve effective cardioprotection studies. The aging heart is characterized by altered proteostasis, DNA instability, epigenetic changes, among others. A vast number of studies has shown that multiple therapeutic strategies, such as ischemic conditioning phenomena and protective drugs are unable to protect the aged heart from myocardial infarction. In this Mini-Review, we will provide an updated state of the art concerning potential new cardioprotective strategies targeting the aging heart.
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Affiliation(s)
- Magda C Díaz-Vesga
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Grupo de Investigación en Ciencias Básicas y Clínicas de la Salud, Pontificia Universidad Javeriana de Cali, Cali, Colombia.,Advanced Center for Chronic Disease (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Úrsula Zúñiga-Cuevas
- Advanced Center for Chronic Disease (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Andrés Ramírez-Reyes
- Advanced Center for Chronic Disease (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Nicolas Herrera-Zelada
- Advanced Center for Chronic Disease (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Iván Palomo
- Thrombosis Research Center, Faculty of Health Sciences, Universidad de Talca, Talca, Chile.,Interuniversity Center for Healthy Aging, Chile
| | - Roberto Bravo-Sagua
- Advanced Center for Chronic Disease (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Interuniversity Center for Healthy Aging, Chile.,Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - Jaime A Riquelme
- Advanced Center for Chronic Disease (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Interuniversity Center for Healthy Aging, Chile
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Chronic metformin treatment decreases cardiac injury during ischemia-reperfusion by attenuating endoplasmic reticulum stress with improved mitochondrial function. Aging (Albany NY) 2021; 13:7828-7845. [PMID: 33746115 PMCID: PMC8034968 DOI: 10.18632/aging.202858] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 02/11/2021] [Indexed: 11/25/2022]
Abstract
Aging impairs mitochondrial function that leads to greater cardiac injury during ischemia and reperfusion. Cardiac endoplasm reticulum (ER) stress increases with age and contributes to mitochondrial dysfunction. Metformin is an anti-diabetic drug that protects cardiac mitochondria during acute ER stress. We hypothesized that metformin treatment would improve preexisting mitochondrial dysfunction in aged hearts by attenuating ER stress, followed by a decrease in cardiac injury during subsequent ischemia and reperfusion. Male young (3 mo.) and aged mice (24 mo.) received metformin (300 mg/kg/day) dissolved in drinking water with sucrose (0.2 g/100 ml) as sweetener for two weeks versus sucrose vehicle alone. Cytosol, subsarcolemmal (SSM), and interfibrillar mitochondria (IFM) were isolated. In separate groups, cardioprotection was evaluated using ex vivo isolated heart perfusion with 25 min. global ischemia and 60 min. reperfusion. Infarct size was measured. The contents of CHOP and cleaved ATF6 were decreased in metformin-treated 24 mo. mice compared to vehicle, supporting a decrease in ER stress. Metformin treatment improved OXPHOS in IFM in 24 mo. using a complex I substrate. Metformin treatment decreased infarct size following ischemia-reperfusion. Thus, metformin feeding decreased cardiac injury in aged mice during ischemia-reperfusion by improving pre-ischemic mitochondrial function via inhibition of ER stress.
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Thompson J, Maceyka M, Chen Q. Targeting ER stress and calpain activation to reverse age-dependent mitochondrial damage in the heart. Mech Ageing Dev 2020; 192:111380. [PMID: 33045249 DOI: 10.1016/j.mad.2020.111380] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/17/2020] [Accepted: 10/01/2020] [Indexed: 12/12/2022]
Abstract
Severity of cardiovascular disease increases markedly in elderly patients. In addition, many therapeutic strategies that decrease cardiac injury in adult patients are invalid in elderly patients. Thus, it is a challenge to protect the aged heart in the context of underlying chronic or acute cardiac diseases including ischemia-reperfusion injury. The cause(s) of this age-related increased damage remain unknown. Aging impairs the function of the mitochondrial electron transport chain (ETC), leading to decreased energy production and increased oxidative stress due to generation of reactive oxygen species (ROS). Additionally, ROS-induced oxidative stress can increase cardiac injury during ischemia-reperfusion by potentiating mitochondrial permeability transition pore (MPTP) opening. Aging leads to increased endoplasmic reticulum (ER) stress, which contributes to mitochondrial dysfunction, including reduced function of the ETC. The activation of both cytosolic and mitochondrial calcium-activated proteases termed calpains leads to mitochondrial dysfunction and decreased ETC function. Intriguingly, mitochondrial ROS generation also induces ER stress, highlighting the dynamic interaction between mitochondria and ER. Here, we discuss the role of ER stress in sensitizing and potentiating mitochondrial dysfunction in response to ischemia-reperfusion, and the promising potential therapeutic benefit of inhibition of ER stress and / or calpains to attenuate cardiac injury in elderly patients.
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Affiliation(s)
- Jeremy Thompson
- Pauley Heart Center, Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, 23298, United States
| | - Michael Maceyka
- Department of Biochemistry & Molecular Biology, Virginia Commonwealth University, Richmond, VA, 23298, United States
| | - Qun Chen
- Pauley Heart Center, Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, 23298, United States.
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7
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Chen Q, Samidurai A, Thompson J, Hu Y, Das A, Willard B, Lesnefsky EJ. Endoplasmic reticulum stress-mediated mitochondrial dysfunction in aged hearts. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165899. [PMID: 32698045 DOI: 10.1016/j.bbadis.2020.165899] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/04/2020] [Accepted: 07/15/2020] [Indexed: 12/11/2022]
Abstract
Aging impairs the mitochondrial electron transport chain (ETC), especially in interfibrillar mitochondria (IFM). Mitochondria are in close contact with the endoplasmic reticulum (ER). Induction of ER stress leads to ETC injury in adult heart mitochondria. We asked if ER stress contributes to the mitochondrial dysfunction during aging. Subsarcolemmal mitochondria (SSM) and IFM were isolated from 3, 18, and 24 mo. C57Bl/6 mouse hearts. ER stress progressively increased with age, especially in 24 mo. mice that manifest mitochondrial dysfunction. OXPHOS was decreased in 24 mo. IFM oxidizing complex I and complex IV substrates. Proteomic analysis showed that the content of multiple complex I subunits was decreased in IFM from 24 mo. hearts, but remained unchanged in in 18 mo. IFM without a decrease in OXPHOS. Feeding 24 mo. old mice with 4-phenylbutyrate (4-PBA) for two weeks attenuated the ER stress and improved mitochondrial function. These results indicate that ER stress contributes to the mitochondrial dysfunction in aged hearts. Attenuation of ER stress is a potential approach to improve mitochondrial function in aged hearts.
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Affiliation(s)
- Qun Chen
- Department of Medicine, Division of Cardiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America
| | - Arun Samidurai
- Department of Medicine, Division of Cardiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America
| | - Jeremy Thompson
- Department of Medicine, Division of Cardiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America
| | - Ying Hu
- Department of Medicine, Division of Cardiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America
| | - Anindita Das
- Department of Medicine, Division of Cardiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America
| | - Belinda Willard
- Proteomics Core, Cleveland Clinic, Cleveland, OH 44106, United States of America
| | - Edward J Lesnefsky
- Department of Medicine, Division of Cardiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America; Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA, 23298, United States of America; Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298, United States of America; McGuire Department of Veterans Affairs Medical Center, Richmond, VA 23249, United States of America.
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8
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Yang M, Zhang Y, Ren J. Acetylation in cardiovascular diseases: Molecular mechanisms and clinical implications. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165836. [PMID: 32413386 DOI: 10.1016/j.bbadis.2020.165836] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 02/07/2023]
Abstract
Acetylation belongs to a class of post-translational modification (PTM) processes that epigenetically regulate gene expression and gene transcriptional activity. Reversible histone acetylation on lysine residues governs the interactions between DNA and histones to mediate chromatin remodeling and gene transcription. Non-histone protein acetylation complicates cellular function whereas acetylation of key mitochondrial enzymes regulates bioenergetic metabolism. Acetylation and deacetylation of functional proteins are essential to the delicated homeostatic regulation of embryonic development, postnatal maturation, cardiomyocyte differentiation, cardiac remodeling and onset of various cardiovascular diseases including obesity, diabetes mellitus, cardiometabolic diseases, ischemia-reperfusion injury, cardiac remodeling, hypertension, and arrhythmias. Histone acetyltransferase (HATs) and histone deacetylases (HDACs) are essential enzymes mainly responsible for the regulation of lysine acetylation levels, thus providing possible drugable targets for therapeutic interventions in the management of cardiovascular diseases.
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Affiliation(s)
- Mingjie Yang
- Department of Cardiology and Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai 210032, China
| | - Yingmei Zhang
- Department of Cardiology and Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai 210032, China.
| | - Jun Ren
- Department of Cardiology and Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai 210032, China.
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Abstract
Mitochondria are key to the cellular response to energetic demand, but are also vital to reactive oxygen species signaling, calcium hemostasis, and regulation of cell death. Cardiac surgical patients with diabetes, heart failure, advanced age, or cardiomyopathies may have underlying mitochondrial dysfunction or be more sensitive to perioperative mitochondrial injury. Mitochondrial dysfunction, due to ischemia/reperfusion injury and an increased systemic inflammatory response due to exposure to cardiopulmonary bypass and surgical tissue trauma, impacts myocardial contractility and predisposes to arrhythmias. Strategies for perioperative mitochondrial protection and recovery include both well-established cardioprotective protocols and targeted therapies that remain under investigation.
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10
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Waheed N, Mahmoud A, Rambarat CA, Pepine CJ. Advances in small-molecule therapy for managing angina pectoris in the elderly. Expert Opin Pharmacother 2019; 20:1471-1481. [PMID: 31107109 DOI: 10.1080/14656566.2019.1615881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Introduction: As our population ages, the prevalence of angina is growing, leading to increased morbidity and decreased quality of life. The management of angina in the elderly is challenging due to drug intolerance and/or drug resistance as well as frailty. Over the past decades, many new therapeutic small molecules have been investigated for the management of angina. Although none of these studies have specifically focused on the therapies for the elderly, they offer promising new avenues for the treatment of angina in the elderly. Areas covered: Herein, the authors provide a review of the recently published literature on the use of small-molecule therapies for angina management in the elderly and provide a brief overview of these therapies. Expert opinion: A variety of therapeutic classes of existing and newer small molecules are emerging for the management of angina in the elderly. An individualized approach to the management of angina in this growing population is critical for good outcomes. Many small molecules are in their initial stages of clinical use, and further research should be conducted on their utility, especially in the elderly.
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Affiliation(s)
- Nida Waheed
- Resident Physician, Department of Medicine, University of Florida , Gainesville , FL , USA
| | - Ahmad Mahmoud
- Resident Physician, Department of Medicine, University of Florida , Gainesville , FL , USA
| | - Cecil A Rambarat
- Division of Cardiovascular Medicine, Department of Medicine, University of Florida , Gainesville , FL , USA
| | - Carl J Pepine
- Division of Cardiovascular Medicine, Department of Medicine, University of Florida , Gainesville , FL , USA
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Liu D, Xu L, Zhang X, Shi C, Qiao S, Ma Z, Yuan J. Snapshot: Implications for mTOR in Aging-related Ischemia/Reperfusion Injury. Aging Dis 2019; 10:116-133. [PMID: 30705773 PMCID: PMC6345330 DOI: 10.14336/ad.2018.0501] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 05/01/2018] [Indexed: 12/15/2022] Open
Abstract
Aging may aggravate the damage and dysfunction of different components of multiorgan and thus increasing multiorgan ischemia/reperfusion (IR) injury. IR injury occurs in many organs and tissues, which is a major cause of morbidity and mortality worldwide. The kinase mammalian target of rapamycin (mTOR), an atypical serine/threonine protein kinase, involves in the pathophysiological process of IR injury. In this review, we first briefly introduce the molecular features of mTOR, the association between mTOR and aging, and especially its role on autophagy. Special focus is placed on the roles of mTOR during ischemic and IR injury. We then clarify the association between mTOR and conditioning phenomena. Following this background, we expand our discussion to potential future directions of research in this area. Collectively, information reviewed herein will serve as a comprehensive reference for the actions of mTOR in IR injury and may be significant for the design of future research and increase the potential of mTOR as a therapeutic target.
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Affiliation(s)
- Dong Liu
- 1State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Liqun Xu
- 1State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China.,2Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China.,3Cadet group 3, School of Basic Medical Sciences, The Fourth Military Medical University, Xi'an 710032, China.,4Laboratory Animal Center, The Fourth Military Medical University, Xi'an 710032, China
| | - Xiaoyan Zhang
- 2Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China.,3Cadet group 3, School of Basic Medical Sciences, The Fourth Military Medical University, Xi'an 710032, China
| | - Changhong Shi
- 4Laboratory Animal Center, The Fourth Military Medical University, Xi'an 710032, China
| | - Shubin Qiao
- 1State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Zhiqiang Ma
- 1State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China.,2Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
| | - Jiansong Yuan
- 1State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
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12
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Garvin AM, Aurigemma NC, Hackenberger JL, Korzick DH. Age and ischemia differentially impact mitochondrial ultrastructure and function in a novel model of age-associated estrogen deficiency in the female rat heart. Pflugers Arch 2017; 469:1591-1602. [PMID: 28776263 DOI: 10.1007/s00424-017-2034-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/10/2017] [Accepted: 07/11/2017] [Indexed: 12/19/2022]
Abstract
Altered mitochondrial respiration, morphology, and quality control collectively contribute to mitochondrial dysfunction in the aged heart. Because myocardial infarction remains the leading cause of death in aged women, the present study utilized a novel rodent model to recapitulate human menopause to interrogate the combination of age and estrogen deficiency on mitochondrial ultrastructure and function with cardiac ischemia/reperfusion (I/R) injury. Female F344 rats were ovariectomized (OVX) at 15 months and studied at 24 months (MO OVX; n = 40) vs adult ovary intact (6 months; n = 41). Temporal declines in estrogen concomitant with increased visceral adipose tissue were observed in MO OVX vs adult. Following in vivo coronary artery ligation or sham surgery, state 3 mitochondrial respiration was selectively reduced by age in subsarcolemmal mitochondria (SSM) and by I/R in interfibrillar mitochondria (IFM); left ventricular maximum dP/dt was reduced in MO OVX (p < 0.05). Elevated cyclophilin D and exacerbated I/R-induced mitochondrial acetylation in MO OVX suggest permeability transition pore involvement and reduced protection vs adult (p < 0.05). Mitochondrial morphology by TEM revealed an altered time course of autophagy coordinate with attenuated Drp1 and LC3BII protein levels with age-associated estrogen loss (p < 0.05). Here, reductions in both SSM and IFM function may play an additive role in enhanced susceptibility to regional I/R injury in aged estrogen-deficient female hearts. Moreover, novel insight into altered cardiac mitochondrial quality control garnered here begins to unravel the potentially important regulatory role of mitochondrial dynamics on sustaining respiratory function in the aged female heart.
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Affiliation(s)
- Alexandra M Garvin
- Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, 106 Noll Laboratory, University Park, PA, 16802, USA
| | - Nicole C Aurigemma
- Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, 106 Noll Laboratory, University Park, PA, 16802, USA
| | - Jenna L Hackenberger
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Donna H Korzick
- Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, 106 Noll Laboratory, University Park, PA, 16802, USA. .,Department of Kinesiology, The Pennsylvania State University, University Park, PA, 16802, USA.
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13
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Lesnefsky EJ, Chen Q, Hoppel CL. Mitochondrial Metabolism in Aging Heart. Circ Res 2017; 118:1593-611. [PMID: 27174952 DOI: 10.1161/circresaha.116.307505] [Citation(s) in RCA: 214] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/05/2016] [Indexed: 02/07/2023]
Abstract
Altered mitochondrial metabolism is the underlying basis for the increased sensitivity in the aged heart to stress. The aged heart exhibits impaired metabolic flexibility, with a decreased capacity to oxidize fatty acids and enhanced dependence on glucose metabolism. Aging impairs mitochondrial oxidative phosphorylation, with a greater role played by the mitochondria located between the myofibrils, the interfibrillar mitochondria. With aging, there is a decrease in activity of complexes III and IV, which account for the decrease in respiration. Furthermore, aging decreases mitochondrial content among the myofibrils. The end result is that in the interfibrillar area, there is ≈50% decrease in mitochondrial function, affecting all substrates. The defective mitochondria persist in the aged heart, leading to enhanced oxidant production and oxidative injury and the activation of oxidant signaling for cell death. Aging defects in mitochondria represent new therapeutic targets, whether by manipulation of the mitochondrial proteome, modulation of electron transport, activation of biogenesis or mitophagy, or the regulation of mitochondrial fission and fusion. These mechanisms provide new ways to attenuate cardiac disease in elders by preemptive treatment of age-related defects, in contrast to the treatment of disease-induced dysfunction.
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Affiliation(s)
- Edward J Lesnefsky
- From the Division of Cardiology, Department of Medicine, Pauley Heart Center (E.J.L, Q.C.), Departments of Biochemistry and Molecular Biology and Physiology and Biophsyics (E.J.L.), Virginia Commonwealth University, Richmond, VA (E.J.L., Q.C.); Medical Service, McGuire Veterans Affairs Medical Center, Richmond, VA (E.J.L.); and Departments of Pharmacology (C.L.H.) and Medicine (E.J.L., C.L.H.), Center for Mitochondrial Disease (C.L.H.), Case Western Reserve University, School of Medicine, Cleveland, OH
| | - Qun Chen
- From the Division of Cardiology, Department of Medicine, Pauley Heart Center (E.J.L, Q.C.), Departments of Biochemistry and Molecular Biology and Physiology and Biophsyics (E.J.L.), Virginia Commonwealth University, Richmond, VA (E.J.L., Q.C.); Medical Service, McGuire Veterans Affairs Medical Center, Richmond, VA (E.J.L.); and Departments of Pharmacology (C.L.H.) and Medicine (E.J.L., C.L.H.), Center for Mitochondrial Disease (C.L.H.), Case Western Reserve University, School of Medicine, Cleveland, OH
| | - Charles L Hoppel
- From the Division of Cardiology, Department of Medicine, Pauley Heart Center (E.J.L, Q.C.), Departments of Biochemistry and Molecular Biology and Physiology and Biophsyics (E.J.L.), Virginia Commonwealth University, Richmond, VA (E.J.L., Q.C.); Medical Service, McGuire Veterans Affairs Medical Center, Richmond, VA (E.J.L.); and Departments of Pharmacology (C.L.H.) and Medicine (E.J.L., C.L.H.), Center for Mitochondrial Disease (C.L.H.), Case Western Reserve University, School of Medicine, Cleveland, OH.
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Lesnefsky EJ, Chen Q, Tandler B, Hoppel CL. Mitochondrial Dysfunction and Myocardial Ischemia-Reperfusion: Implications for Novel Therapies. Annu Rev Pharmacol Toxicol 2017; 57:535-565. [PMID: 27860548 PMCID: PMC11060135 DOI: 10.1146/annurev-pharmtox-010715-103335] [Citation(s) in RCA: 267] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondria have emerged as key participants in and regulators of myocardial injury during ischemia and reperfusion. This review examines the sites of damage to cardiac mitochondria during ischemia and focuses on the impact of these defects. The concept that mitochondrial damage during ischemia leads to cardiac injury during reperfusion is addressed. The mechanisms that translate ischemic mitochondrial injury into cellular damage, during both ischemia and early reperfusion, are examined. Next, we discuss strategies that modulate and counteract these mechanisms of mitochondrial-driven injury. The new concept that mitochondria are not merely stochastic sites of oxidative and calcium-mediated injury but that they activate cellular responses of mitochondrial remodeling and cellular reactions that modulate the balance between cell death and recovery is reviewed, and the therapeutic implications of this concept are discussed.
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Affiliation(s)
- Edward J Lesnefsky
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia 23298; ,
- Medical Service, McGuire Veterans Affairs Medical Center, Richmond, Virginia 23249;
| | - Qun Chen
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia 23298; ,
| | - Bernard Tandler
- Department of Biological Sciences, Case Western Reserve University School of Dental Medicine, Cleveland, Ohio 44106;
| | - Charles L Hoppel
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106;
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
- Center for Mitochondrial Disease, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
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Mitochondrial Dysfunction in Cardiovascular Aging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 982:451-464. [PMID: 28551802 DOI: 10.1007/978-3-319-55330-6_24] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mitochondria are the prime source of ATP in cardiomyocytes. Impairment of mitochondrial metabolism results in damage to existing proteins and DNA. Such deleterious effects are part and parcel of the aging process, reducing the ability of cardiomyocytes to counter stress, such as myocardial infarction and consequent reperfusion. In such conditions, mitochondria in the heart of aged individuals exhibit decreased oxidative phosphorylation, decreased ATP production, and increased net reactive oxygen species production; all of these effects are independent of the decrease in number of mitochondria that occurs in these situations. Rather than being associated with the mitochondrial population in toto, these defects are almost exclusively confined to those organelles positioned between myofibrils (interfibrillar mitochondria). It is in complex III and IV where these dysfunctional aspects are manifested. In an apparent effort to correct mitochondrial metabolic defects, affected organelles are to some extent eliminated by mitophagy; at the same time, new, unaffected organelles are generated by fission of mitochondria. Because these cardiac health issues are localized to specific mitochondria, these organelles offer potential targets for therapeutic approaches that could favorably affect the aging process in heart.
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16
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Keenaghan M, Sun L, Wang A, Hyodo E, Homma S, Ten VS. Intrauterine growth restriction impairs right ventricular response to hypoxia in adult male rats. Pediatr Res 2016; 80:547-53. [PMID: 27557421 DOI: 10.1038/pr.2016.124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/23/2016] [Indexed: 11/09/2022]
Abstract
BACKGROUND Intrauterine growth restriction (IUGR) predisposes to cardiovascular diseases in adulthood. The mechanisms of this phenomenon remain cryptic. We hypothesized that heart mitochondria in IUGR-born adult rats are more sensitive to acute hypoxia which translates into dysfunctional cardiac response to hypoxic stress. METHODS Adult IUGR-born male rats (the offspring of dams fed with calories-restricted diet during pregnancy) were exposed to acute hypoxic stress with echocardiographic assessment of cardiac function. In parallel, mitochondrial respiration in organelles isolated from left ventricle (LV) and right ventricle (RV) was tested in normoxic and anoxic conditions. The extent of post-anoxic inhibition of mitochondrial respiration and cardiac function was compared with controls, non-IUGR rats. RESULTS Compared with controls, in the IUGR rats hypoxia significantly reduced only RV contractility, evidenced by decreased fractional shortening, functional area of contraction, and tricuspid annular plane systolic excursion. In isolated mitochondria, anoxic challenge inhibited respiratory chain in both groups of rats. However, compared with controls, the extent of anoxic mitochondrial depression was significantly greater in IUGR-born rats, but only in the organelles isolated from RV. CONCLUSIONS In adult IUGR-born rats, mitochondria from RV are hypersensitive to oxygen deprivation and this translates into maladaptive RV cardiac response to acute hypoxia.
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Affiliation(s)
- Michael Keenaghan
- Department of Pediatrics, Kings County Hospital Center, Brooklyn, New York.,Department of Pediatrics, St. Georges University, Grenada, West Indies
| | - Lena Sun
- Department of Anesthesiology, Columbia University, New York, New York.,Department of Pediatrics, Columbia University, New York, New York
| | - Aili Wang
- Department of Anesthesiology, Columbia University, New York, New York
| | - Eiichi Hyodo
- Department of Medicine, Columbia University, New York, New York
| | - Sinichi Homma
- Department of Medicine, Columbia University, New York, New York
| | - Vadim S Ten
- Department of Pediatrics, Columbia University, New York, New York
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17
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Schilling JM, Patel HH. Non-canonical roles for caveolin in regulation of membrane repair and mitochondria: implications for stress adaptation with age. J Physiol 2015; 594:4581-9. [PMID: 26333003 DOI: 10.1113/jp270591] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 08/04/2015] [Indexed: 12/22/2022] Open
Abstract
Many different theories of ageing have been proposed but none has served the unifying purpose of defining a molecular target that can limit the structural and functional decline associated with age that ultimately leads to the demise of the organism. We propose that the search for a molecule with these unique properties must account for regulation of the signalling efficiency of multiple cellular functions that degrade with age due to a loss of a particular protein. We suggest caveolin as one such molecule that serves as a regulator of key processes in signal transduction. We define a particular distinction between cellular senescence and ageing and propose that caveolin plays a distinct role in each of these processes. Caveolin is traditionally thought of as a membrane-localized protein regulating signal transduction via membrane enrichment of specific signalling molecules. Ultimately we focus on two non-canonical roles for caveolin - membrane repair and regulation of mitochondrial function - which may be novel features of stress adaptation, especially in the setting of ageing. The end result of preserving membrane structure and mitochondrial function is maintenance of homeostatic signalling, preserving barrier function, and regulating energy production for cell survival and resilient ageing.
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Affiliation(s)
- Jan M Schilling
- VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA, 92161, USA.,Department of Anesthesiology, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Hemal H Patel
- VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA, 92161, USA.,Department of Anesthesiology, University of California, San Diego, La Jolla, CA, 92093, USA
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Acetyl-L-carnitine increases mitochondrial protein acetylation in the aged rat heart. Mech Ageing Dev 2015; 145:39-50. [PMID: 25660059 DOI: 10.1016/j.mad.2015.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 11/24/2014] [Accepted: 01/27/2015] [Indexed: 12/30/2022]
Abstract
Previously we showed that in vivo treatment of elderly Fisher 344 rats with acetylcarnitine abolished the age-associated defect in respiratory chain complex III in interfibrillar mitochondria and improved the functional recovery of the ischemic/reperfused heart. Herein, we explored mitochondrial protein acetylation as a possible mechanism for acetylcarnitine's effect. In vivo treatment of elderly rats with acetylcarnitine restored cardiac acetylcarnitine content and increased mitochondrial protein lysine acetylation and increased the number of lysine-acetylated proteins in cardiac subsarcolemmal and interfibrillar mitochondria. Enzymes of the tricarboxylic acid cycle, mitochondrial β-oxidation, and ATP synthase of the respiratory chain showed the greatest acetylation. Acetylation of isocitrate dehydrogenase, long-chain acyl-CoA dehydrogenase, complex V, and aspartate aminotransferase was accompanied by decreased catalytic activity. Several proteins were found to be acetylated only after treatment with acetylcarnitine, suggesting that exogenous acetylcarnitine served as the acetyl-donor. Two-dimensional fluorescence difference gel electrophoresis analysis revealed that acetylcarnitine treatment also induced changes in mitochondrial protein amount; a two-fold or greater increase/decrease in abundance was observed for thirty one proteins. Collectively, our data provide evidence for the first time that in the aged rat heart in vivo administration of acetylcarnitine provides acetyl groups for protein acetylation and affects the amount of mitochondrial proteins.
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19
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Fernandez-Sanz C, Ruiz-Meana M, Castellano J, Miro-Casas E, Nuñez E, Inserte J, Vázquez J, Garcia-Dorado D. Altered FoF1 ATP synthase and susceptibility to mitochondrial permeability transition pore during ischaemia and reperfusion in aging cardiomyocytes. Thromb Haemost 2015; 113:441-51. [PMID: 25631625 DOI: 10.1160/th14-10-0901] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/15/2015] [Indexed: 12/27/2022]
Abstract
Aging is a major determinant of the incidence and severity of ischaemic heart disease. Preclinical information suggests the existence of intrinsic cellular alterations that contribute to ischaemic susceptibility in senescent myocardium, by mechanisms not well established. We investigated the role of altered mitochondrial function in the adverse effect of aging. Isolated perfused hearts from old mice (> 20 months) displayed increased ischaemia-reperfusion injury as compared to hearts from adult mice (6 months) despite delayed onset of ischaemic rigor contracture. In cardiomyocytes from aging hearts there was a more rapid decline of mitochondrial membrane potential (Δψm) as compared to young ones, but ischaemic rigor shortening was also delayed. Transient recovery of Δψm observed during ischaemia, secondary to the reversal of mitochondrial FoF1 ATP synthase to ATPase mode, was markedly reduced in aging cardiomyocytes. Proteomic analysis demonstrated increased oxidation of different subunits of ATP synthase. Altered bionergetics in aging cells was associated with reduced mitochondrial calcium uptake and more severe cytosolic calcium overload during ischaemia-reperfusion. Despite attenuated ROS burst and mitochondrial calcium overload, mitochondrial permeability transition pore (mPTP) opening and cell death was increased in reperfused aged cells. In vitro studies demonstrated a significantly reduced calcium retention capacity in interfibrillar mitochondria from aging hearts. Our results identify altered FoF1 ATP synthase and increased sensitivity of mitochondria to undergo mPTP opening as important determinants of the reduced tolerance to ischaemia-reperfusion in aging hearts. Because ATP synthase has been proposed to conform mPTP, it is tempting to hypothesise that oxidation of ATP synthase underlie both phenomena.
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Affiliation(s)
| | - Marisol Ruiz-Meana
- Marisol Ruiz-Meana, Cardiologia, Vall d'Hebron Institut de Recerca, Hospital Universitari Vall d'Hebron- Universitat Autonoma de Barcelona, Pg Vall d'Hebron 119-129, 08035 Barcelona, Spain, Tel.: +34 93 489 4037, Fax:+34 93 489 4032, E-mail:
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20
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Schilling JM, Roth DM, Patel HH. Caveolins in cardioprotection - translatability and mechanisms. Br J Pharmacol 2015; 172:2114-25. [PMID: 25377989 DOI: 10.1111/bph.13009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 10/27/2014] [Accepted: 11/03/2014] [Indexed: 12/24/2022] Open
Abstract
Translation of preclinical treatments for ischaemia-reperfusion injury into clinical therapies has been limited by a number of factors. This review will focus on a single mode of cardiac protection related to a membrane scaffolding protein, caveolin, which regulates protective signalling as well as myocyte ultrastructure in the setting of ischaemic stress. Factors that have limited the clinical translation of protection will be considered specifically in terms of signalling and structural defects. The potential of caveolin to overcome barriers to protection with the ultimate hope of clinical translation will be discussed.
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Affiliation(s)
- Jan M Schilling
- VA San Diego Healthcare System, San Diego, CA, USA; Department of Anesthesiology, University of California, San Diego, La Jolla, CA, USA
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21
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Hollander JM, Thapa D, Shepherd DL. Physiological and structural differences in spatially distinct subpopulations of cardiac mitochondria: influence of cardiac pathologies. Am J Physiol Heart Circ Physiol 2014; 307:H1-14. [PMID: 24778166 DOI: 10.1152/ajpheart.00747.2013] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cardiac tissue contains discrete pools of mitochondria that are characterized by their subcellular spatial arrangement. Subsarcolemmal mitochondria (SSM) exist below the cell membrane, interfibrillar mitochondria (IFM) reside in rows between the myofibrils, and perinuclear mitochondria are situated at the nuclear poles. Microstructural imaging of heart tissue coupled with the development of differential isolation techniques designed to sequentially separate spatially distinct mitochondrial subpopulations have revealed differences in morphological features including shape, absolute size, and internal cristae arrangement. These findings have been complemented by functional studies indicating differences in biochemical parameters and, potentially, functional roles for the ATP generated, based upon subcellular location. Consequently, mitochondrial subpopulations appear to be influenced differently during cardiac pathologies including ischemia/reperfusion, heart failure, aging, exercise, and diabetes mellitus. These influences may be the result of specific structural and functional disparities between mitochondrial subpopulations such that the stress elicited by a given cardiac insult differentially impacts subcellular locales and the mitochondria contained within. The goal of this review is to highlight some of the inherent structural and functional differences that exist between spatially distinct cardiac mitochondrial subpopulations as well as provide an overview of the differential impact of various cardiac pathologies on spatially distinct mitochondrial subpopulations. As an outcome, we will instill a basis for incorporating subcellular spatial location when evaluating the impact of cardiac pathologies on the mitochondrion. Incorporation of subcellular spatial location may offer the greatest potential for delineating the influence of cardiac pathology on this critical organelle.
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22
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Molecular mechanism and physiological role of active-deactive transition of mitochondrial complex I. Biochem Soc Trans 2014; 41:1325-30. [PMID: 24059527 PMCID: PMC3990385 DOI: 10.1042/bst20130088] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The unique feature of mitochondrial complex I is the so-called A/D transition (active–deactive transition). The A-form catalyses rapid oxidation of NADH by ubiquinone (k ~104 min−1) and spontaneously converts into the D-form if the enzyme is idle at physiological temperatures. Such deactivation occurs in vitro in the absence of substrates or in vivo during ischaemia, when the ubiquinone pool is reduced. The D-form can undergo reactivation given both NADH and ubiquinone availability during slow (k ~1–10 min−1) catalytic turnover(s). We examined known conformational differences between the two forms and suggested a mechanism exerting A/D transition of the enzyme. In addition, we discuss the physiological role of maintaining the enzyme in the D-form during the ischaemic period. Accumulation of the D-form of the enzyme would prevent reverse electron transfer from ubiquinol to FMN which could lead to superoxide anion generation. Deactivation would also decrease the initial burst of respiration after oxygen reintroduction. Therefore the A/D transition could be an intrinsic protective mechanism for lessening oxidative damage during the early phase of reoxygenation. Exposure of Cys39 of mitochondrially encoded subunit ND3 makes the D-form susceptible for modification by reactive oxygen species and nitric oxide metabolites which arrests the reactivation of the D-form and inhibits the enzyme. The nature of thiol modification defines deactivation reversibility, the reactivation timescale, the status of mitochondrial bioenergetics and therefore the degree of recovery of the ischaemic tissues after reoxygenation.
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23
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Babot M, Birch A, Labarbuta P, Galkin A. Characterisation of the active/de-active transition of mitochondrial complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1083-92. [PMID: 24569053 PMCID: PMC4331042 DOI: 10.1016/j.bbabio.2014.02.018] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Revised: 02/14/2014] [Accepted: 02/17/2014] [Indexed: 12/12/2022]
Abstract
Oxidation of NADH in the mitochondrial matrix of aerobic cells is catalysed by mitochondrial complex I. The regulation of this mitochondrial enzyme is not completely understood. An interesting characteristic of complex I from some organisms is the ability to adopt two distinct states: the so-called catalytically active (A) and the de-active, dormant state (D). The A-form in situ can undergo de-activation when the activity of the respiratory chain is limited (i.e. in the absence of oxygen). The mechanisms and driving force behind the A/D transition of the enzyme are currently unknown, but several subunits are most likely involved in the conformational rearrangements: the accessory subunit 39 kDa (NDUFA9) and the mitochondrially encoded subunits, ND3 and ND1. These three subunits are located in the region of the quinone binding site. The A/D transition could represent an intrinsic mechanism which provides a fast response of the mitochondrial respiratory chain to oxygen deprivation. The physiological role of the accumulation of the D-form in anoxia is most probably to protect mitochondria from ROS generation due to the rapid burst of respiration following reoxygenation. The de-activation rate varies in different tissues and can be modulated by the temperature, the presence of free fatty acids and divalent cations, the NAD+/NADH ratio in the matrix, the presence of nitric oxide and oxygen availability. Cysteine-39 of the ND3 subunit, exposed in the D-form, is susceptible to covalent modification by nitrosothiols, ROS and RNS. The D-form in situ could react with natural effectors in mitochondria or with pharmacological agents. Therefore the modulation of the re-activation rate of complex I could be a way to ameliorate the ischaemia/reperfusion damage. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira. The potential mechanism of complex I A/D transition is discussed. An —SH group exposed in the D-form is susceptible to covalent modification. The role of A/D transition in tissue response to ischaemia is proposed.
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Affiliation(s)
- Marion Babot
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Amanda Birch
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Paola Labarbuta
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Alexander Galkin
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK.
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24
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Peart JN, Pepe S, Reichelt ME, Beckett N, See Hoe L, Ozberk V, Niesman IR, Patel HH, Headrick JP. Dysfunctional survival-signaling and stress-intolerance in aged murine and human myocardium. Exp Gerontol 2013; 50:72-81. [PMID: 24316036 DOI: 10.1016/j.exger.2013.11.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 11/03/2013] [Accepted: 11/26/2013] [Indexed: 11/26/2022]
Abstract
Changes in cytoprotective signaling may influence cardiac aging, and underpin sensitization to ischemic insult and desensitization to 'anti-ischemic' therapies. We tested whether age-dependent shifts in ischemia-reperfusion (I-R) tolerance in murine and human myocardium are associated with reduced efficacies and coupling of membrane, cytoplasmic and mitochondrial survival-signaling. Hormesis (exemplified in ischemic preconditioning; IPC) and expression of proteins influencing signaling/stress-resistance were also assessed in mice. Mouse hearts (18 vs. 2-4 mo) and human atrial tissue (75±2 vs. 55±2 yrs) exhibited profound age-dependent reductions in I-R tolerance. In mice aging negated cardioprotection via IPC, G-protein coupled receptor (GPCR) agonism (opioid, A1 and A3 adenosine receptors) and distal protein kinase c (PKC) activation (4 nM phorbol 12-myristate 13-acetate; PMA). In contrast, p38-mitogen activated protein kinase (p38-MAPK) activation (1 μM anisomycin), mitochondrial ATP-sensitive K(+) channel (mKATP) opening (50 μM diazoxide) and permeability transition pore (mPTP) inhibition (0.2 μM cyclosporin A) retained protective efficacies in older hearts (though failed to eliminate I-R tolerance differences). A similar pattern of change in protective efficacies was observed in human tissue. Murine hearts exhibited molecular changes consistent with altered membrane control (reduced caveolin-3, cholesterol and caveolae), kinase signaling (reduced p70 ribosomal s6 kinase; p70s6K) and stress-resistance (increased G-protein receptor kinase 2, GRK2; glycogen synthase kinase 3β, GSK3β; and cytosolic cytochrome c). In summary, myocardial I-R tolerance declines with age in association with dysfunctional hormesis and transduction of survival signals from GPCRs/PKC to mitochondrial effectors. Differential changes in proteins governing caveolar and mitochondrial function may contribute to signal dysfunction and stress-intolerance.
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Affiliation(s)
- Jason N Peart
- Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Australia
| | - Salvatore Pepe
- Heart Research, Murdoch Children's Research Institute, Parkville, VIC, Australia; Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Melissa E Reichelt
- Department of Physiology, University of Melbourne, Parkville, VIC, Australia
| | - Nikkie Beckett
- Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Australia
| | - Louise See Hoe
- Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Australia
| | - Victoria Ozberk
- Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Australia
| | | | - Hemal H Patel
- VA San Diego Healthcare System, San Diego, USA; Department of Anesthesiology, University of California San Diego, USA
| | - John P Headrick
- Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Southport, Australia.
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Akasheva DU, Plokhova EV, Strazhesko ID, Dudinskaya EN, Tkacheva ON. HEART AND AGE (PART III): MODIFYING AGEING PROCESSES. КАРДИОВАСКУЛЯРНАЯ ТЕРАПИЯ И ПРОФИЛАКТИКА 2013. [DOI: 10.15829/1728-8800-2013-5-91-96] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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26
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Lesnefsky EJ, Hoppel CL. Aged rat heart: Modulation of age-related respiratory defects decreases ischemic-reflow injury. Health (London) 2013. [DOI: 10.4236/health.2013.51001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Li QW, Lu XY, You Y, Sun H, Liu XY, Ai JZ, Tan RZ, Chen TL, Chen MZ, Wang HL, Wei YQ, Zhou Q. Comparative proteomic analysis suggests that mitochondria are involved in autosomal recessive polycystic kidney disease. Proteomics 2012; 12:2556-70. [PMID: 22718539 DOI: 10.1002/pmic.201100590] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Autosomal recessive polycystic kidney disease (ARPKD), characterized by ectatic collecting duct, is an infantile form of PKD occurring in 1 in 20 000 births. Despite having been studied for many years, little is known about the underlying mechanisms. In the current study, we employed, for the first time, a MS-based comparative proteomics approach to investigate the differently expressed proteins between kidney tissue samples of four ARPKD and five control individuals. Thirty two differently expressed proteins were identified and six of the identified protein encoding genes performed on an independent group (three ARPKD subjects, four control subjects) were verified by semi-quantitative RT-PCR, and part of them were further validated by Western blot and immunohistochemistry. Moreover, similar alteration tendency was detected after downregulation of PKHD1 by small interfering RNA in HEK293T cell. Interestingly, most of the identified proteins are associated with mitochondria. This implies that mitochondria may be implicated in ARPKD. Furthermore, the String software was utilized to investigate the biological association network, which is based on known and predicted protein interactions. In conclusion, our findings depicted a global understanding of ARPKD progression and provided a promising resource of targeting protein, and shed some light further investigation of ARPKD.
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Affiliation(s)
- Qing-Wei Li
- Core Facility of Genetically Engineered Mice, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Sichuan, People's Republic of China
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Blockade of electron transport before ischemia protects mitochondria and decreases myocardial injury during reperfusion in aged rat hearts. Transl Res 2012; 160:207-16. [PMID: 22698829 PMCID: PMC3423471 DOI: 10.1016/j.trsl.2012.01.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 01/25/2012] [Accepted: 01/26/2012] [Indexed: 12/29/2022]
Abstract
Myocardial injury is increased in the aged heart following ischemia and reperfusion (I-R) in both humans and experimental models. Hearts from aged 24-month-old Fischer 344 rats sustain greater cell death and decreased contractile recovery after I-R compared with 6-month-old adult controls. Cardiac mitochondria incur damage during I-R contributing to cell death. Aged rats have a defect in complex III of the mitochondrial electron transport chain (ETC) localized to the interfibrillar population of cardiac mitochondria (IFM), situated in the interior of the cardiomyocyte among the myofibrils. The defect involves the quinol oxidation site (Qo) and increases the production of reactive oxygen species (ROS) in the baseline state. Ischemia further decreases complex III activity via functional inactivation of the iron-sulfur subunit. We studied the contribution of ischemia-induced defects in complex III with the increased cardiac injury in the aged heart. The reversible blockade of the ETC proximal to complex III during ischemia using amobarbital protects mitochondria against ischemic damage, removing the ischemia component of mitochondrial dysfunction. Reperfusion of the aged heart in the absence of ischemic mitochondrial damage decreases net ROS production from mitochondria and reduces cell death. Thus, even despite the persistence of the age-related defects in electron transport, protection against ischemic damage to mitochondria can reduce injury in the aged heart. The direct therapeutic targeting of mitochondria protects against ischemic damage and decreases cardiac injury during reperfusion in the high risk elderly heart.
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Blockade of electron transport at the onset of reperfusion decreases cardiac injury in aged hearts by protecting the inner mitochondrial membrane. J Aging Res 2012; 2012:753949. [PMID: 22619720 PMCID: PMC3347723 DOI: 10.1155/2012/753949] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 11/23/2011] [Accepted: 12/27/2011] [Indexed: 12/23/2022] Open
Abstract
Myocardial injury is increased in the aged heart following ischemia-reperfusion (ISC-REP) compared to adult hearts. Intervention at REP with ischemic postconditioning decreases injury in the adult heart by attenuating mitochondrial driven cell injury. Unfortunately, postconditioning is ineffective in aged hearts. Blockade of electron transport at the onset of REP with the reversible inhibitor amobarbital (AMO) decreases injury in adult hearts. We tested if AMO treatment at REP protects the aged heart via preservation of mitochondrial integrity. Buffer-perfused elderly Fischer 344 24 mo. rat hearts underwent 25 min global ISC and 30 min REP. AMO (2.5 mM) or vehicle was given for 3 min at the onset of REP. Subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria were isolated after REP. Oxidative phosphorylation (OXPHOS) and mitochondrial inner membrane potential were measured. AMO treatment at REP decreased cardiac injury. Compared to untreated ISC-REP, AMO improved inner membrane potential in SSM and IFM during REP, indicating preserved inner membrane integrity. Thus, direct pharmacologic modulation of electron transport at REP protects mitochondria and decreases cardiac injury in the aged heart, even when signaling-induced pathways of postconditioning that are upstream of mitochondria are ineffective.
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Peart JN, See Hoe L, Pepe S, Johnson P, Headrick JP. Opposing effects of age and calorie restriction on molecular determinants of myocardial ischemic tolerance. Rejuvenation Res 2012; 15:59-70. [PMID: 22236144 DOI: 10.1089/rej.2011.1226] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We test the hypothesis that moderate calorie restriction (CR) reverses negative influences of age on molecular determinants of myocardial stress resistance. Postischemic contractile dysfunction, cellular damage, and expression of regulators of autophagy/apoptosis and of prosurvival and prodeath kinases were assessed in myocardium from young adult (YA; 2- to 4-month-old) and middle-aged (MA; 12-month-old) mice, and MA mice subjected to 14 weeks of 40% CR (MA-CR). Ventricular dysfunction after 25%±2%), as was cell death indicated by troponin I (TnI) efflux (1,701±214 ng vs. 785±102 ng in YA). MA hearts exhibited 30% and 65% reductions in postischemic Beclin1 and Parkin, respectively, yet 50% lower proapoptotic Bax and 85% higher antiapoptotic Bcl2, increasing the Bcl2/Bax ratio. Age did not influence Akt or p38-mitogen-activated protein kinase (MAPK) expression; reduced expression of increasingly phosphorylated ribosomal protein S6 kinase (p70S6K), increased expression of dephosphorylated glycogen synthase kinase 3β (GSK3β) and enhanced postischemic p38-MAPK phosphorylation. CR countered the age-related decline in ischemic tolerance, improving contractile recovery (60%±4%) and reducing cell death (123±22 ng of TnI). Protection was not associated with changes in Parkin or Bax, whereas CR partially limited the age-related decline in Beclin1 and further increased Bcl2. CR counteracted age-related changes in p70S6K, increased Akt levels, and reduced p38-MAPK (albeit increasing preischemic phosphorylation), and paradoxically reduced postischemic GSK3β phosphorylation. In summary, moderate age worsens cardiac ischemic tolerance; this is associated with reduced expression of autophagy regulators, dysregulation of p70S6K and GSK3β, and postischemic p38-MAPK activation. CR counters age effects on postischemic dysfunction/cell death; this is associated with reversal of age effects on p70S6K, augmentation of Akt and Bcl2 levels, and preischemic p38-MAPK activation. Age and CR thus impact on distinct determinants of ischemic tolerance, although p70S6K signaling presents a point of convergence.
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Affiliation(s)
- Jason N Peart
- Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Gold Coast Campus, Queensland, Australia.
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Ischemic preconditioning: the role of mitochondria and aging. Exp Gerontol 2011; 47:1-7. [PMID: 22100642 DOI: 10.1016/j.exger.2011.11.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/24/2011] [Accepted: 11/02/2011] [Indexed: 11/22/2022]
Abstract
Aging represents a triple threat for myocardial infarction (MI). Not only does the incidence of MI increase with age, but the heart becomes more susceptible to MI induced damage and protective interventions such as ischemic preconditioning (IPC) become less effective. Therefore, any rational therapeutic strategy must be built around the ability to combat the detrimental effects of ischemia in aged individuals. To accomplish this, we need to develop a better understanding of how ischemic damage, protection, and aging are linked. In this regard, mitochondria have emerged as a common theme. First, mitochondria contribute to cell damage during ischemia-reperfusion (IR) and are central to cell death. Second, the protective signaling pathways activated by IPC converge on mitochondria, and the opening of mitochondrial ion channels alone is sufficient to elicit protection. Finally, mitochondria clearly influence the aging process, and specific defects in mitochondrial activity are associated with age-related functional decline. This review will summarize the effects of aging on myocardial IR injury and discuss relevant and emerging strategies to protect against MI with an emphasis on mitochondrial function.
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Calabrese V, Cornelius C, Dinkova-Kostova AT, Iavicoli I, Di Paola R, Koverech A, Cuzzocrea S, Rizzarelli E, Calabrese EJ. Cellular stress responses, hormetic phytochemicals and vitagenes in aging and longevity. Biochim Biophys Acta Mol Basis Dis 2011; 1822:753-83. [PMID: 22108204 DOI: 10.1016/j.bbadis.2011.11.002] [Citation(s) in RCA: 280] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 10/31/2011] [Accepted: 11/01/2011] [Indexed: 12/30/2022]
Abstract
Modulation of endogenous cellular defense mechanisms represents an innovative approach to therapeutic intervention in diseases causing chronic tissue damage, such as in neurodegeneration. This paper introduces the emerging role of exogenous molecules in hormetic-based neuroprotection and the mitochondrial redox signaling concept of hormesis and its applications to the field of neuroprotection and longevity. Maintenance of optimal long-term health conditions is accomplished by a complex network of longevity assurance processes that are controlled by vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, such as polyphenols and L-carnitine/acetyl-L-carnitine, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. Hormesis provides the central underpinning of neuroprotective responses, providing a framework for explaining the common quantitative features of their dose response relationships, their mechanistic foundations, their relationship to the concept of biological plasticity as well as providing a key insight for improving the accuracy of the therapeutic dose of pharmaceutical agents within the highly heterogeneous human population. This paper describes in mechanistic detail how hormetic dose responses are mediated for endogenous cellular defense pathways including sirtuin, Nrfs and related pathways that integrate adaptive stress responses in the prevention of neurodegenerative diseases. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.
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Calabrese V, Cornelius C, Cuzzocrea S, Iavicoli I, Rizzarelli E, Calabrese EJ. Hormesis, cellular stress response and vitagenes as critical determinants in aging and longevity. Mol Aspects Med 2011; 32:279-304. [PMID: 22020114 DOI: 10.1016/j.mam.2011.10.007] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 10/11/2011] [Indexed: 12/14/2022]
Abstract
Understanding mechanisms of aging and determinants of life span will help to reduce age-related morbidity and facilitate healthy aging. Average lifespan has increased over the last centuries, as a consequence of medical and environmental factors, but maximal life span remains unchanged. Extension of maximal life span is currently possible in animal models with measures such as genetic manipulations and caloric restriction (CR). CR appears to prolong life by reducing reactive oxygen species (ROS)-mediated oxidative damage. But ROS formation, which is positively implicated in cellular stress response mechanisms, is a highly regulated process controlled by a complex network of intracellular signaling pathways. By sensing the intracellular nutrient and energy status, the functional state of mitochondria, and the concentration of ROS produced in mitochondria, the longevity network regulates life span across species by co-ordinating information flow along its convergent, divergent and multiply branched signaling pathways, including vitagenes which are genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, such as carnosine, carnitines or polyphenols, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. The hormetic dose-response, challenges long-standing beliefs about the nature of the dose-response in a lowdose zone, having the potential to affect significantly the design of pre-clinical studies and clinical trials as well as strategies for optimal patient dosing in the treatment of numerous diseases. Given the broad cytoprotective properties of the heat shock response there is now strong interest in discovering and developing pharmacological agents capable of inducing stress responses. In this review we discuss the most current and up to date understanding of the possible signaling mechanisms by which caloric restriction, as well hormetic caloric restriction-mimetics compounds by activating vitagenes can enhance defensive systems involved in bioenergetic and stress resistance homeostasis with consequent impact on longevity processes.
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Affiliation(s)
- Vittorio Calabrese
- Department of Chemistry, University of Catania, Viale Andrea Doria, 95100 Catania, Italy.
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Szczepanek K, Chen Q, Larner AC, Lesnefsky EJ. Cytoprotection by the modulation of mitochondrial electron transport chain: the emerging role of mitochondrial STAT3. Mitochondrion 2011; 12:180-9. [PMID: 21930250 DOI: 10.1016/j.mito.2011.08.011] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 08/06/2011] [Accepted: 08/31/2011] [Indexed: 12/25/2022]
Abstract
The down regulation of mitochondrial electron transport is an emerging mechanism of cytoprotective intervention that is effective in pathologic settings such as myocardial ischemia and reperfusion when the continuation of mitochondrial respiration produces reactive oxygen species, mitochondrial calcium overload, and the release of cytochrome c to activate cell death programs. The initial target of deranged electron transport is the mitochondria themselves. In the first part of this review, we describe this concept and summarize different approaches used to regulate mitochondrial respiration by targeting complex I as a proximal site in the electron transport chain (ETC) in order to favor the cytoprotection. The second part of the review highlights the emerging role of signal transducer and activator of transcription 3 (STAT3) in the direct, non-transcriptional regulation of ETC, as an example of a genetic approach to modulate respiration. Recent studies indicate that a pool of STAT3 resides in the mitochondria where it is necessary for the maximal activity of complexes I and II of the electron transport chain (ETC). The overexpression of mitochondrial-targeted STAT3 results in a partial blockade of electron transport at complexes I and II that does not impair mitochondrial membrane potential nor enhance the production of reactive oxygen species (ROS). The targeting of transcriptionally-inactive STAT3 to mitochondria attenuates damage to mitochondria during cell stress, resulting in decreased production of ROS and retention of cytochrome c by mitochondria. The overexpression of STAT3 targeted to mitochondria unveils a novel protective approach mediated by modulation of mitochondrial respiration that is independent of STAT3 transcriptional activity. The limitation of mitochondrial respiration under pathologic circumstances can be approached by activation and overexpression of endogenous signaling mechanisms in addition to pharmacologic means. The regulation of mitochondrial respiration comprises a cardioprotective paradigm to decrease cellular injury during ischemia and reperfusion.
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Affiliation(s)
- Karol Szczepanek
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
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Miller JA, Runkle SA, Tjalkens RB, Philbert MA. 1,3-Dinitrobenzene-induced metabolic impairment through selective inactivation of the pyruvate dehydrogenase complex. Toxicol Sci 2011; 122:502-11. [PMID: 21551353 DOI: 10.1093/toxsci/kfr102] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Prolonged exposure to the chemical intermediate, 1,3-dinitrobenzene (1,3-DNB), produces neuropathology in the central nervous system of rodents analogous to that observed in various conditions of acute energy deprivation including thiamine deficiency and Leigh's necrotizing encephalopathy. Increased production of reactive intermediates in addition to induction of oxidative stress has been implicated in the neurotoxic mechanism of 1,3-DNB, but a clear metabolic target has not been determined. Here we propose that similar to thiamine deficiency, the effects of 1,3-DNB on metabolic status may be due to inhibition of the thiamine-dependent α-ketoacid dehydrogenase complexes. The effects of 1,3-DNB on astroglial metabolic status and α-ketoacid dehydrogenase activity were evaluated using rat C6 glioma cells. Exposure to 1,3-DNB resulted in altered morphology and biochemical dysfunction consistent with disruption of oxidative energy metabolism. Cotreatment with acetyl-carnitine or acetoacetate attenuated morphological and metabolic effects of 1,3-DNB exposure as well as increased cell viability. 1,3-DNB exposure inhibited pyruvate dehydrogenase complex (PDHc) and the inhibition correlated with the loss of lipoic acid (LA) immunoreactivity, suggesting that modification of LA is a potential mechanism of inhibition. Treatment with antioxidants and thiol-containing compounds failed to protect against loss of LA. Alternatively, inhibition of dihydrolipoamide dehydrogenase, the E3 component of the complex attenuated loss of LA. Collectively, these data suggest that 1,3-DNB impairs oxidative energy metabolism through direct inhibition of the PDHc and that this impairment is due to perturbations in the function of protein-bound LA.
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Affiliation(s)
- James A Miller
- Center for Environmental Medicine, Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
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Mingorance C, Rodríguez-Rodríguez R, Justo ML, Alvarez de Sotomayor M, Herrera MD. Critical update for the clinical use of L-carnitine analogs in cardiometabolic disorders. Vasc Health Risk Manag 2011; 7:169-76. [PMID: 21490942 PMCID: PMC3072740 DOI: 10.2147/vhrm.s14356] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Indexed: 01/12/2023] Open
Abstract
Acetyl-L-carnitine (ALC) and propionyl-L-carnitine (PLC) are two naturally occurring carnitine derivates formed by carnitine acetyltransferase. The beneficial cardiovascular effects of ALC and PLC have been extensively evaluated in animals and humans during the last 20 years. For instance, many clinical trials have suggested ALC and PLC as potential strategies in the management of peripheral arterial disease, heart and cerebral ischemia, and congestive heart failure. As a result, several experts have already aimed to revise the clinical evidence supporting the therapeutic use of ALC and PLC. On the basis of their conclusions, our aim was a critical review of the effectiveness of ALC and PLC in the treatment of cardiovascular diseases. Type 2 diabetes mellitus is an independent risk factor for the development of cardiovascular disease. Therefore we also describe recent studies that have addressed the emerging use of ALC and PLC amelioration of the insulin resistant state and its related morbidities.
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Affiliation(s)
- Carmen Mingorance
- Department of Pharmacology, School of Pharmacy, University of Seville, Seville, Spain
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37
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Cellular Stress Responses, Mitostress and Carnitine Insufficiencies as Critical Determinants in Aging and Neurodegenerative Disorders: Role of Hormesis and Vitagenes. Neurochem Res 2010; 35:1880-915. [DOI: 10.1007/s11064-010-0307-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2010] [Indexed: 02/07/2023]
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Lemieux H, Vazquez EJ, Fujioka H, Hoppel CL. Decrease in mitochondrial function in rat cardiac permeabilized fibers correlates with the aging phenotype. J Gerontol A Biol Sci Med Sci 2010; 65:1157-64. [PMID: 20801909 DOI: 10.1093/gerona/glq141] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We measured the loss of cardiac mitochondrial function related to aging in males of three rat strains presenting with different longevity and aging phenotypes: the Fischer 344 (F344), the Brown Norway (BN), and the hybrid F344×BN. The F344 rat has a short life span and a ∼45% decrease in coupled mitochondrial oxidation in the cardiac permeabilized fibers from the old rats compared with the young rats. Citrate synthase activity in the permeabilized fibers (mitochondrial content) did not change significantly with aging. The BN live longer compared with the F344 and have a 15%-18% loss of mitochondrial respiration in the aged rats compared with the young rats. The differences are not significant. In hybrids, more resistant to aging than are the BN and the F344, mitochondrial function is preserved during aging. The difference in longevity of the different strains is correlated with mitochondrial dysfunction in the heart, suggesting the importance of mitochondria in cardiac aging.
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Affiliation(s)
- Hélène Lemieux
- Center for Mitochondrial Disease, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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39
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Abstract
The mitochondrion is the most important organelle in determining continued cell survival and cell death. Mitochondrial dysfunction leads to many human maladies, including cardiovascular diseases, neurodegenerative disease, and cancer. These mitochondria-related pathologies range from early infancy to senescence. The central premise of this review is that if mitochondrial abnormalities contribute to the pathological state, alleviating the mitochondrial dysfunction would contribute to attenuating the severity or progression of the disease. Therefore, this review will examine the role of mitochondria in the etiology and progression of several diseases and explore potential therapeutic benefits of targeting mitochondria in mitigating the disease processes. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate and manipulate mitochondrial function and genomics for therapeutic benefit. These approaches to treat mitochondrial dysfunction rationally could lead to selective protection of cells in different tissues and various disease states. However, most of these approaches are in their infancy.
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40
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Shim YH. Cardioprotection and ageing. Korean J Anesthesiol 2010; 58:223-30. [PMID: 20498769 PMCID: PMC2872846 DOI: 10.4097/kjae.2010.58.3.223] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 03/08/2010] [Accepted: 03/08/2010] [Indexed: 11/10/2022] Open
Abstract
With an increase in the elderly population and an increase in the prevalence of age-related cardiovascular disease, anesthesiologists are increasingly being faced with elderly patients with known or suspected ischemic heart disease in the perioperative period. Although early reperfusion remains the best strategy to reduce ischemic injury, reperfusion may damage the myocardium. Adjuvant therapy to revascularization is therefore necessary. To develop better strategies to prevent ischemia-reperfusion injury in older patients, we need to understand the aged myocardium, which has undergone structural and functional changes relative to the normal myocardium, resulting in reduced functional capacity and vulnerability to ischemia-reperfusion injury. In addition, innate or acquired cardioprotection deteriorates with aging. These changes in the aged myocardium might explain why there is poor translation of basic research findings from young animals to older patients. In this review, I discuss changes in intracellular signaling associated with myocardial ageing that have an effect on ischemia-reperfusion injury, and I discuss the efficacy of cardioprotection afforded by ischemic and pharmacologic pre-and post-conditioning in the aged myocardium. Finally, I outline strategies to restore protection in the aged myocardium.
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Affiliation(s)
- Yon Hee Shim
- Department of Anesthesiology and Pain Medicine and Anaesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea
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Heather LC, Carr CA, Stuckey DJ, Pope S, Morten KJ, Carter EE, Edwards LM, Clarke K. Critical role of complex III in the early metabolic changes following myocardial infarction. Cardiovasc Res 2010; 85:127-36. [PMID: 19666902 DOI: 10.1093/cvr/cvp276] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
AIMS The chronically infarcted rat heart has multiple defects in metabolism, yet the location of the primary metabolic abnormality arising after myocardial infarction is unknown. Therefore, we investigated cardiac mitochondrial metabolism shortly after infarction. METHODS AND RESULTS Myocardial infarctions (n = 11) and sham operations (n = 9) were performed on Wistar rats, at 2 weeks cardiac function was assessed using echocardiography, and rats were grouped into failing (ejection fraction < or =45%), moderately impaired (46-60%), and sham-operated (>60%). Respiration rates were decreased by 28% in both subsarcolemmal and interfibrillar mitochondria isolated from failing hearts, compared with sham-operated controls. However, respiration rates were not impaired in mitochondria from hearts with moderately impaired function. The mitochondrial defect in the failing hearts was located within the electron transport chain (ETC), as respiration rates were suppressed to the same extent when fatty acids, ketone bodies, or glutamate were used as substrates. Complex III protein levels were decreased by 46% and complex III activity was decreased by 26%, in mitochondria from failing hearts, but all other ETC complexes were unchanged. Decreased complex III activity was accompanied by a three-fold increase in complex III-derived H(2)O(2) production, decreased cardiolipin content, and a 60% decrease in mitochondrial cytochrome c levels from failing hearts. Respiration rates, complex III activity, cardiolipin content, and reactive oxygen species generation rates correlated with ejection fraction. CONCLUSION In conclusion, a specific defect in complex III occurred acutely after myocardial infarction, which increased oxidative damage and impaired mitochondrial respiration. The extent of mitochondrial dysfunction in the failing heart was proportional to the degree of cardiac dysfunction induced by myocardial infarction.
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Affiliation(s)
- Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK.
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Rosca MG, Lemieux H, Hoppel CL. Mitochondria in the elderly: Is acetylcarnitine a rejuvenator? Adv Drug Deliv Rev 2009; 61:1332-1342. [PMID: 19720100 DOI: 10.1016/j.addr.2009.06.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Accepted: 06/01/2009] [Indexed: 12/21/2022]
Abstract
Endogenous acetylcarnitine is an indicator of acetyl-CoA synthesized by multiple metabolic pathways involving carbohydrates, amino acids, fatty acids, sterols, and ketone bodies, and utilized mainly by the tricarboxylic acid cycle. Acetylcarnitine supplementation has beneficial effects in elderly animals and humans, including restoration of mitochondrial content and function. These effects appear to be dose-dependent and occur even after short-term therapy. In order to set the stage for understanding the mechanism of action of acetylcarnitine, we review the metabolism and role of this compound. We suggest that acetylation of mitochondrial proteins leads to a specific increase in mitochondrial gene expression and mitochondrial protein synthesis. In the aged rat heart, this effect is translated to increased cytochrome b content, restoration of complex III activity, and oxidative phosphorylation, resulting in amelioration of the age-related mitochondrial defect.
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Affiliation(s)
- Mariana G Rosca
- Center for Mitochondrial Diseases and Departments of Medicine and Pharmacology, Case Western Reserve University, Cleveland, Ohio
| | - Hélène Lemieux
- Center for Mitochondrial Diseases and Departments of Medicine and Pharmacology, Case Western Reserve University, Cleveland, Ohio
| | - Charles L Hoppel
- Center for Mitochondrial Diseases and Departments of Medicine and Pharmacology, Case Western Reserve University, Cleveland, Ohio
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Galkin A, Abramov AY, Frakich N, Duchen MR, Moncada S. Lack of oxygen deactivates mitochondrial complex I: implications for ischemic injury? J Biol Chem 2009; 284:36055-36061. [PMID: 19861410 DOI: 10.1074/jbc.m109.054346] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
For S-nitrosothiols and peroxynitrite to interfere with the activity of mitochondrial complex I, prior transition of the enzyme from its active (A) to its deactive, dormant (D) state is necessary. We now demonstrate accumulation of the D-form of complex I in human epithelial kidney cells after prolonged hypoxia. Upon reoxygenation after hypoxia there was an initial delay in the return of the respiration rate to normal. This was due to the accumulation of the D-form and its slow, substrate-dependent reconversion to the A-form. Reconversion to the A-form could be prevented by prolonged incubation with endogenously generated NO. We propose that the hypoxic transition from the A-form to the D-form of complex I may be protective, because it would act to reduce the electron burst and the formation of free radicals during reoxygenation. However, this may become an early pathophysiological event when NO-dependent formation of S-nitrosothiols or peroxynitrite structurally modifies complex I in its D-form and impedes its return to the active state. These observations provide a mechanism to account for the severe cell injury that follows hypoxia and reoxygenation when accompanied by NO generation.
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Affiliation(s)
- Alexander Galkin
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT.
| | - Andrey Y Abramov
- Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, United Kingdom
| | - Nanci Frakich
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT
| | - Michel R Duchen
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT
| | - Salvador Moncada
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT
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Hoppel CL, Tandler B, Fujioka H, Riva A. Dynamic organization of mitochondria in human heart and in myocardial disease. Int J Biochem Cell Biol 2009; 41:1949-56. [PMID: 19446651 DOI: 10.1016/j.biocel.2009.05.004] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 05/04/2009] [Accepted: 05/06/2009] [Indexed: 01/13/2023]
Abstract
Heart mitochondria, which, depending on their location within cardiomyofibers, are classified as either subsarcolemmal or interfibrillar, are the major sources of the high energy compound, adenosine triphosphate. Physiological differences between these two populations are reflected by differences in the morphology of their cristae, with those of subsarcolemmal mitochondria being mostly lamelliform, and those of interfibrillar mitochondria being mostly tubular. What determines the configuration of cristae, not only in cardiac mitochondria but in mitochondria in general, is unclear. The morphology of cardiac mitochondria, as well as their physiology, is responsive to the exigencies posed by a large variety of pathological situations. Giant cardiac mitochondria make an appearance in certain types of cardiomyopathy and as a result of dietary, pharmacological, and toxicological manipulation; such megamitochondria probably arise by a combination of fusion and true growth. Some of these enlarged organelles occasionally contain a membrane-bound deposit of beta-glycogen. Those giant mitochondria induced by experimental treatment usually can be restored to normal dimensions simply by supplying the missing nutrient or by deleting the noxious substance. In some conditions, such as endurance training and ischemia, the mitochondrial matrices become pale. Dense rods or plates are present in the outer compartment of mitochondria under certain conditions. Biochemical alterations in cardiac mitochondria appear to be important in heart failure. In aging, only interfibrillar mitochondria exhibit such changes, with the subsarcolemmal mitochondria unaffected. In certain heart afflictions, biochemical defects are not accompanied by obvious morphological transformations. Mitochondria clearly play a cardinal role in homeostasis of the heart.
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Affiliation(s)
- Charles L Hoppel
- Department of Pharmacology and Medicine and Center for Mitochondrial Disease, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
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Exercise training improves functional post-ischemic recovery in senescent heart. Exp Gerontol 2009; 44:177-82. [DOI: 10.1016/j.exger.2008.10.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 09/16/2008] [Accepted: 10/09/2008] [Indexed: 11/19/2022]
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Atapattu DN, Albrecht RM, McClenahan DJ, Czuprynski CJ. Dynamin-2-dependent targeting of mannheimia haemolytica leukotoxin to mitochondrial cyclophilin D in bovine lymphoblastoid cells. Infect Immun 2008; 76:5357-65. [PMID: 18765728 PMCID: PMC2573345 DOI: 10.1128/iai.00221-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Revised: 06/09/2008] [Accepted: 08/26/2008] [Indexed: 11/20/2022] Open
Abstract
Exotoxins which belong to the family containing the RTX toxins (repeats in toxin) contribute to a variety of important human and animal diseases. One example of such a toxin is the potent leukotoxin (LKT) produced by the bovine respiratory pathogen Mannheimia haemolytica. LKT binds to CD18, resulting in the death of bovine leukocytes. In this study, we showed that internalized LKT binds to the outer mitochondrial membrane, which results in the release of cytochrome c and collapse of the mitochondrial membrane potential (psi(m)). Incubation of bovine lymphoblastoid cells (BL-3 cells) with the mitochondrial membrane-stabilizing agent cyclosporine (CSA) reduced LKT-mediated cytotoxicity, cytochrome c release, and collapse of the psi(m). Coimmunoprecipitation and intracellular binding studies suggested that LKT binds to the mitochondrial matrix protein cyclophilin D. We also demonstrated that LKT mobilizes the vesicle scission protein dynamin-2 from mitochondria to the cell membrane. Incubation with CSA depleted mitochondrial dynamin-2 in BL-3 cells, making it unavailable for vesicle scission and LKT internalization. The results of this study show that LKT trafficking and LKT-mediated cell death involve dynamin-2 and cyclophilin D, in a process that can be prevented by the mitochondrial membrane-protecting function of CSA.
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Affiliation(s)
- Dhammika N Atapattu
- Department of Pathobiological Sciences, 2015 Linden Drive West, University of Wisconsin-Madison, Madison, WI 53706, USA
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Lesnefsky EJ, Hoppel CL. Cardiolipin as an oxidative target in cardiac mitochondria in the aged rat. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1020-7. [PMID: 18515061 DOI: 10.1016/j.bbabio.2008.05.444] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 05/21/2008] [Accepted: 05/22/2008] [Indexed: 02/07/2023]
Abstract
The aged heart sustains greater injury during ischemia (ISC) and reperfusion (REP) compared to the adult heart. In the Fischer 344 (F344) rat, aging decreases oxidative phosphorylation and complex III activity increasing the production of reactive oxygen species in interfibrillar mitochondria (IFM) located among the myofibrils. In the isolated, perfused 24 month old elderly F344 rat heart 25 min of stop-flow ISC causes additional damage to complex III, further decreasing the rate of oxidative phosphorylation. We did not observe further progressive mitochondrial damage during REP. We next asked if ISC or REP increased oxidative damage within mitochondria of the aged heart. Cardiolipin (CL) is a phospholipid unique to mitochondria consisting predominantly of four linoleic acid residues (C18:2). Following ISC and REP in the aged heart, there is a new CL species containing three oxygen atoms added to one linoleic residue. ISC alone was sufficient to generate this new oxidized molecular species of CL. Based upon oxidative damage to CL, complex III activity, and oxidative phosphorylation, mitochondrial damage thus occurs in the aged heart mainly during ISC, rather than during REP. Mitochondrial damage during ischemia sets the stage for mitochondrial-driven cardiomyocyte injury during reperfusion in the aged heart.
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Affiliation(s)
- Edward J Lesnefsky
- Department of Medicine, Division of Cardiology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Abstract
Advanced age is a strong independent predictor for death, disability, and morbidity in patients with structural heart disease. With the projected increase in the elderly population and the prevalence of age-related cardiovascular disabilities worldwide, the need to understand the biology of the aging heart, the mechanisms for age-mediated cardiac vulnerability, and the development of strategies to limit myocardial dysfunction in the elderly have never been more urgent. Experimental evidence in animal models indicate attenuation in cardioprotective pathways with aging, yet limited information is available regarding age-related changes in the human heart. Human cardiac aging generates a complex phenotype, only partially replicated in animal models. Here, we summarize current understanding of the aging heart stemming from clinical and experimental studies, and we highlight targets for protection of the vulnerable senescent myocardium. Further progress mandates assessment of human tissue to dissect specific aging-associated genomic and proteomic dynamics, and their functional consequences leading to increased susceptibility of the heart to injury, a critical step toward designing novel therapeutic interventions to limit age-related myocardial dysfunction and promote healthy aging.
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Affiliation(s)
- Arshad Jahangir
- Marriott Heart Disease Research Program, Division of Cardiovascular Diseases, and Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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Guo D, Nguyen T, Ogbi M, Tawfik H, Ma G, Yu Q, Caldwell RW, Johnson JA. Protein kinase C-epsilon coimmunoprecipitates with cytochrome oxidase subunit IV and is associated with improved cytochrome-c oxidase activity and cardioprotection. Am J Physiol Heart Circ Physiol 2007; 293:H2219-30. [PMID: 17660387 DOI: 10.1152/ajpheart.01306.2006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We have utilized an in situ rat coronary ligation model to establish a PKC-epsilon cytochrome oxidase subunit IV (COIV) coimmunoprecipitation in myocardium exposed to ischemic preconditioning (PC). Ischemia-reperfusion (I/R) damage and PC protection were confirmed using tetrazolium-based staining methods and serum levels of cardiac troponin I. Homogenates prepared from the regions at risk (RAR) and not at risk (RNAR) for I/R injury were fractionated into cell-soluble (S), 600 g low-speed centrifugation (L), Percoll/Optiprep density gradient-purified mitochondrial (M), and 100,000 g particulate (P) fractions. COIV immunoreactivity and cytochrome-c oxidase activity measurements estimated the percentages of cellular mitochondria in S, L, M, and P fractions to be 0, 55, 29, and 16%, respectively. We observed 18, 3, and 3% of PKC-delta, -epsilon, and -zeta isozymes in the M fraction under basal conditions. Following PC, we observed a 61% increase in PKC-epsilon levels in the RAR M fraction compared with the RNAR M fraction. In RAR mitochondria, we also observed a 2.8-fold increase in PKC-epsilon serine 729 phosphoimmunoreactivity (autophosphorylation), indicating the presence of activated PKC-epsilon in mitochondria following PC. PC administered before prolonged I/R induced a 1.9-fold increase in the coimmunoprecipitation of COIV, with anti-PKC-epsilon antisera and a twofold enhancement of cytochrome-c oxidase activity. Our results suggest that PKC-epsilon may interact with COIV as a component of the cardioprotection in PC. Induction of this interaction may provide a novel therapeutic target for protecting the heart from I/R damage.
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Affiliation(s)
- Dehuang Guo
- Department of Pharmacology & Toxicology, School of Medicine, Medical College of Georgia, Augusta, Georgia 30912-2300, USA
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Pi Y, Goldenthal MJ, Marín-García J. Mitochondrial involvement in IGF-1 induced protection of cardiomyocytes against hypoxia/reoxygenation injury. Mol Cell Biochem 2007; 301:181-9. [PMID: 17264981 DOI: 10.1007/s11010-007-9410-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Accepted: 12/06/2006] [Indexed: 12/13/2022]
Abstract
Studies in animal models of myocardial ischemia-reperfusion revealed that the administration of insulin-like growth factor (IGF-1) can provide substantial cardioprotective effect. However, the mechanisms by which IGF-1 prevents myocardial ischemia-reperfusion injury are not fully understood. This study addresses whether mitochondrial bioenergetic pathways are involved in the cardioprotective effects of IGF-1. Single cardiomyocytes from adult rats were incubated in the absence or presence of IGF-1 for 60 min and subjected to 60 min hypoxia followed by 30 min reoxygenation at 37 degrees C. Mitochondrial function was evaluated by assessment of enzyme activities of oxidative phosphorylation and Krebs cycle pathways. Hypoxia/reoxygenation (HR) caused significant inhibition of mitochondrial respiratory complex IV and V activities and of the Krebs cycle enzyme citrate synthase, whereas pretreatment with IGF-1 maintained enzyme activities in myocytes at or near control levels. Mitochondrial membrane potential, evaluated with JC-1 staining, was significantly higher in IGF-1 + HR- treated myocytes than in HR alone, with levels similar to those found in normal control cardiomyocytes. In addition, IGF-1 reduced both HR-induced lactate dehydrogenase (LDH) release and malondialdehyde production (an indicator of lipid peroxidation) in cardiomyocytes. These results suggest that IGF-1 protects cardiomyocytes from HR injury via stabilizing mitochondria and reducing reactive oxidative species (ROS) damage.
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Affiliation(s)
- YeQing Pi
- The Molecular Cardiology and Neuromuscular Institute, Highland Park, NJ, USA
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