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PolyGA targets the ER stress-adaptive response by impairing GRP75 function at the MAM in C9ORF72-ALS/FTD. Acta Neuropathol 2022; 144:939-966. [PMID: 36121477 PMCID: PMC9547809 DOI: 10.1007/s00401-022-02494-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 08/18/2022] [Accepted: 09/06/2022] [Indexed: 01/26/2023]
Abstract
ER stress signaling is linked to the pathophysiological and clinical disease manifestations in amyotrophic lateral sclerosis (ALS). Here, we have investigated ER stress-induced adaptive mechanisms in C9ORF72-ALS/FTD, focusing on uncovering early endogenous neuroprotective mechanisms and the crosstalk between pathological and adaptive responses in disease onset and progression. We provide evidence for the early onset of ER stress-mediated adaptive response in C9ORF72 patient-derived motoneurons (MNs), reflected by the elevated increase in GRP75 expression. These transiently increased GRP75 levels enhance ER-mitochondrial association, boosting mitochondrial function and sustaining cellular bioenergetics during the initial stage of disease, thereby counteracting early mitochondrial deficits. In C9orf72 rodent neurons, an abrupt reduction in GRP75 expression coincided with the onset of UPR, mitochondrial dysfunction and the emergence of PolyGA aggregates, which co-localize with GRP75. Similarly, the overexpression of PolyGA in WT cortical neurons or C9ORF72 patient-derived MNs led to the sequestration of GRP75 within PolyGA inclusions, resulting in mitochondrial calcium (Ca2+) uptake impairments. Corroborating these findings, we found that PolyGA aggregate-bearing human post-mortem C9ORF72 hippocampal dentate gyrus neurons not only display reduced expression of GRP75 but also exhibit GRP75 sequestration within inclusions. Sustaining high GRP75 expression in spinal C9orf72 rodent MNs specifically prevented ER stress, normalized mitochondrial function, abrogated PolyGA accumulation in spinal MNs, and ameliorated ALS-associated behavioral phenotype. Taken together, our results are in line with the notion that neurons in C9ORF72-ALS/FTD are particularly susceptible to ER-mitochondrial dysfunction and that GRP75 serves as a critical endogenous neuroprotective factor. This neuroprotective pathway, is eventually targeted by PolyGA, leading to GRP75 sequestration, and its subsequent loss of function at the MAM, compromising mitochondrial function and promoting disease onset.
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IK Ca channels control breast cancer metabolism including AMPK-driven autophagy. Cell Death Dis 2022; 13:902. [PMID: 36302750 PMCID: PMC9613901 DOI: 10.1038/s41419-022-05329-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/28/2022] [Accepted: 10/07/2022] [Indexed: 11/30/2022]
Abstract
Ca2+-activated K+ channels of intermediate conductance (IK) are frequently overexpressed in breast cancer (BC) cells, while IK channel depletion reduces BC cell proliferation and tumorigenesis. This raises the question, of whether and mechanistically how IK activity interferes with the metabolic activity and energy consumption rates, which are fundamental for rapidly growing cells. Using BC cells obtained from MMTV-PyMT tumor-bearing mice, we show that both, glycolysis and mitochondrial ATP-production are reduced in cells derived from IK-deficient breast tumors. Loss of IK altered the sub-/cellular K+- and Ca2+- homeostasis and mitochondrial membrane potential, ultimately resulting in reduced ATP-production and metabolic activity. Consequently, we find that BC cells lacking IK upregulate AMP-activated protein kinase activity to induce autophagy compensating the glycolytic and mitochondrial energy shortage. Our results emphasize that IK by modulating cellular Ca2+- and K+-dynamics contributes to the remodeling of metabolic pathways in cancer. Thus, targeting IK channel might disturb the metabolic activity of BC cells and reduce malignancy.
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PS-NPs Induced Neurotoxic Effects in SHSY-5Y Cells via Autophagy Activation and Mitochondrial Dysfunction. Brain Sci 2022; 12:brainsci12070952. [PMID: 35884757 PMCID: PMC9321807 DOI: 10.3390/brainsci12070952] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/09/2022] [Accepted: 07/18/2022] [Indexed: 02/05/2023] Open
Abstract
Polystyrene nanoparticles (PS-NPs) are organic pollutants that are widely detected in the environment and organisms, posing potential threats to both ecosystems and human health. PS-NPs have been proven to penetrate the blood–brain barrier and increase the incidence of neurodegenerative diseases. However, information relating to the pathogenic molecular mechanism is still unclear. This study investigated the neurotoxicity and regulatory mechanisms of PS-NPs in human neuroblastoma SHSY-5Y cells. The results show that PS-NPs caused obvious mitochondrial damages, as evidenced by inhibited cell proliferation, increased lactate dehydrogenase release, stimulated oxidative stress responses, elevated Ca2+ level and apoptosis, and reduced mitochondrial membrane potential and adenosine triphosphate levels. The increased release of cytochrome c and the overexpression of apoptosis-related proteins apoptotic protease activating factor-1 (Apaf-1), cysteinyl aspartate specific proteinase-3 (caspase-3), and caspase-9 indicate the activation of the mitochondrial apoptosis pathway. In addition, the upregulation of autophagy markers light chain 3-II (LC3-II), Beclin-1, and autophagy-related protein (Atg) 5/12/16L suggests that PS-NPs could promote autophagy in SHSY-5Y cells. The RNA interference of Beclin-1 confirms the regulatory role of autophagy in PS-NP-induced neurotoxicity. The administration of antioxidant N-acetylcysteine (NAC) significantly attenuated the cytotoxicity and autophagy activation induced by PS-NP exposure. Generally, PS-NPs could induce neurotoxicity in SHSY-5Y cells via autophagy activation and mitochondria dysfunction, which was modulated by mitochondrial oxidative stress. Mitochondrial damages caused by oxidative stress could potentially be involved in the pathological mechanisms for PS-NP-induced neurodegenerative diseases.
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Mihajlovic M, Vinken M. Mitochondria as the Target of Hepatotoxicity and Drug-Induced Liver Injury: Molecular Mechanisms and Detection Methods. Int J Mol Sci 2022; 23:ijms23063315. [PMID: 35328737 PMCID: PMC8951158 DOI: 10.3390/ijms23063315] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 12/12/2022] Open
Abstract
One of the major mechanisms of drug-induced liver injury includes mitochondrial perturbation and dysfunction. This is not a surprise, given that mitochondria are essential organelles in most cells, which are responsible for energy homeostasis and the regulation of cellular metabolism. Drug-induced mitochondrial dysfunction can be influenced by various factors and conditions, such as genetic predisposition, the presence of metabolic disorders and obesity, viral infections, as well as drugs. Despite the fact that many methods have been developed for studying mitochondrial function, there is still a need for advanced and integrative models and approaches more closely resembling liver physiology, which would take into account predisposing factors. This could reduce the costs of drug development by the early prediction of potential mitochondrial toxicity during pre-clinical tests and, especially, prevent serious complications observed in clinical settings.
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Gowda P, Reddy PH, Kumar S. Deregulated mitochondrial microRNAs in Alzheimer's disease: Focus on synapse and mitochondria. Ageing Res Rev 2022; 73:101529. [PMID: 34813976 PMCID: PMC8692431 DOI: 10.1016/j.arr.2021.101529] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/17/2021] [Accepted: 11/16/2021] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia and is currently one of the biggest public health concerns in the world. Mitochondrial dysfunction in neurons is one of the major hallmarks of AD. Emerging evidence suggests that mitochondrial miRNAs potentially play important roles in the mitochondrial dysfunctions, focusing on synapse in AD progression. In this meta-analysis paper, a comprehensive literature review was conducted to identify and discuss the (1) role of mitochondrial miRNAs that regulate mitochondrial and synaptic functions; (2) the role of various factors such as mitochondrial dynamics, biogenesis, calcium signaling, biological sex, and aging on synapse and mitochondrial function; (3) how synapse damage and mitochondrial dysfunctions contribute to AD; (4) the structure and function of synapse and mitochondria in the disease process; (5) latest research developments in synapse and mitochondria in healthy and disease states; and (6) therapeutic strategies that improve synaptic and mitochondrial functions in AD. Specifically, we discussed how differences in the expression of mitochondrial miRNAs affect ATP production, oxidative stress, mitophagy, bioenergetics, mitochondrial dynamics, synaptic activity, synaptic plasticity, neurotransmission, and synaptotoxicity in neurons observed during AD. However, more research is needed to confirm the locations and roles of individual mitochondrial miRNAs in the development of AD.
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Affiliation(s)
- Prashanth Gowda
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Neuroscience & Pharmacology, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Neurology, Departments of School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Public Health Department of Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - P Hemachandra Reddy
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Neuroscience & Pharmacology, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Neurology, Departments of School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Public Health Department of Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, USA; Department of Speech, Language and Hearing Sciences, School Health Professions, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
| | - Subodh Kumar
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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Ravi B, Kanwar P, Sanyal SK, Bheri M, Pandey GK. VDACs: An Outlook on Biochemical Regulation and Function in Animal and Plant Systems. Front Physiol 2021; 12:683920. [PMID: 34421635 PMCID: PMC8375762 DOI: 10.3389/fphys.2021.683920] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/30/2021] [Indexed: 12/12/2022] Open
Abstract
The voltage-dependent anion channels (VDACs) are the most abundant proteins present on the outer mitochondrial membrane. They serve a myriad of functions ranging from energy and metabolite exchange to highly debatable roles in apoptosis. Their role in molecular transport puts them on the center stage as communicators between cytoplasmic and mitochondrial signaling events. Beyond their general role as interchangeable pores, members of this family may exhibit specific functions. Even after nearly five decades of their discovery, their role in plant systems is still a new and rapidly emerging field. The information on biochemical regulation of VDACs is limited. Various interacting proteins and post-translational modifications (PTMs) modulate VDAC functions, amongst these, phosphorylation is quite noticeable. In this review, we have tried to give a glimpse of the recent advancements in the biochemical/interactional regulation of plant VDACs. We also cover a critical analysis on the importance of PTMs in the functional regulation of VDACs. Besides, the review also encompasses numerous studies which can identify VDACs as a connecting link between Ca2+ and reactive oxygen species signaling in special reference to the plant systems.
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Affiliation(s)
| | | | | | | | - Girdhar K. Pandey
- Department of Plant Molecular Biology, University of Delhi, New Delhi, India
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Sanders OD, Rajagopal JA, Rajagopal L. Menthol to Induce Non-shivering Thermogenesis via TRPM8/PKA Signaling for Treatment of Obesity. J Obes Metab Syndr 2021; 30:4-11. [PMID: 33071240 PMCID: PMC8017329 DOI: 10.7570/jomes20038] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/25/2020] [Accepted: 06/12/2020] [Indexed: 12/25/2022] Open
Abstract
Increasing basal energy expenditure via uncoupling protein 1 (UCP1)-dependent non-shivering thermogenesis is an attractive therapeutic strategy for treatment of obesity. Transient receptor potential melastatin 8 (TRPM8) channel activation by cold and cold mimetics induces UCP1 transcription and prevents obesity in animals, but the clinical relevance of this relationship remains incompletely understood. A review of TRPM8 channel agonism for treatment of obesity focusing on menthol was undertaken. Adipocyte TRPM8 activation results in Ca2+ influx and protein kinase A (PKA) activation, which induces mitochondrial elongation, mitochondrial localization to lipid droplets, lipolysis, β-oxidation, and UCP1 expression. Ca2+-induced mitochondrial reactive oxygen species activate UCP1. In animals, TRPM8 agonism increases basal metabolic rate, non-shivering thermogenesis, oxygen consumption, exercise endurance, and fatty acid oxidation and decreases abdominal fat percentage. Menthol prevents high-fat diet-induced obesity, glucose intolerance, insulin resistance, and liver triacylglycerol accumulation. Hypothalamic TRPM8 activation releases glucagon, which activates PKA and promotes catabolism. TRPM8 polymorphisms are associated with obesity. In humans, oral menthol and other TRPM8 agonists have little effect. However, topical menthol appears to increase core body temperature and metabolic rate. A randomized clinical control trial of topical menthol in obese patients is warranted.
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Affiliation(s)
| | | | - Lekshmy Rajagopal
- Oto-Rhino-Laryngology, College of Physicians and Surgeons, Mumbai, India
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8
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T lymphocytes from malignant hyperthermia-susceptible mice display aberrations in intracellular calcium signaling and mitochondrial function. Cell Calcium 2020; 93:102325. [PMID: 33310301 DOI: 10.1016/j.ceca.2020.102325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 01/05/2023]
Abstract
Gain-of-function RyR1-p.R163C mutation in ryanodine receptors type 1 (RyR1) deregulates Ca2+ signaling and mitochondrial function in skeletal muscle and causes malignant hyperthermia in humans and mice under triggering conditions. We investigated whether T lymphocytes from heterozygous RyR1-p.R163C knock-in mutant mice (HET T cells) display measurable aberrations in resting cytosolic Ca2+ concentration ([Ca2+]i), Ca2+ release from the store, store-operated Ca2+ entry (SOCE), and mitochondrial inner membrane potential (ΔΨm) compared with T lymphocytes from wild-type mice (WT T cells). We explored whether these variables can be used to distinguish between T cells with normal and altered RyR1 genotype. HET and WT T cells were isolated from spleen and lymph nodes and activated in vitro using phytohemagglutinin P. [Ca2+]i and ΔΨm dynamics were examined using Fura 2 and tetramethylrhodamine methyl ester fluorescent dyes, respectively. Activated HET T cells displayed elevated resting [Ca2+]i, diminished responses to Ca2+ mobilization with thapsigargin, and decreased rate of [Ca2+]i elevation in response to SOCE compared with WT T cells. Pretreatment of HET T cells with ryanodine or dantrolene sodium reduced disparities in the resting [Ca2+]i and ability of thapsigargin to mobilize Ca2+ between HET and WT T cells. While SOCE elicited dissipation of the ΔΨm in WT T cells, it produced ΔΨm hyperpolarization in HET T cells. When used as the classification variable, the amplitude of thapsigargin-induced Ca2+ transient showed the best promise in predicting the presence of RyR1-p.R163C mutation. Other significant variables identified by machine learning analysis were the ratio of resting cytosolic Ca2+ level to the amplitude of thapsigargin-induced Ca2+ transient and an integral of changes in ΔΨm in response to SOCE. Our study demonstrated that gain-of-function mutation in RyR1 significantly affects Ca2+ signaling and mitochondrial fiction in T lymphocytes, which suggests that this mutation may cause altered immune responses in its carrier. Our data link the RyR1-p.R163C mutation, which causes inherited skeletal muscle diseases, to deregulation of Ca2+ signaling and mitochondrial function in immune T cells and establish proof-of-principle for in vitro T cell-based diagnostic assay for hereditary RyR1 hyperfunction.
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Olgar Y, Tuncay E, Degirmenci S, Billur D, Dhingra R, Kirshenbaum L, Turan B. Ageing-associated increase in SGLT2 disrupts mitochondrial/sarcoplasmic reticulum Ca 2+ homeostasis and promotes cardiac dysfunction. J Cell Mol Med 2020; 24:8567-8578. [PMID: 32652890 PMCID: PMC7412693 DOI: 10.1111/jcmm.15483] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/30/2020] [Accepted: 05/24/2020] [Indexed: 12/12/2022] Open
Abstract
The prevalence of death from cardiovascular disease is significantly higher in elderly populations; the underlying factors that contribute to the age‐associated decline in cardiac performance are poorly understood. Herein, we identify the involvement of sodium/glucose co‐transporter gene (SGLT2) in disrupted cellular Ca2+‐homeostasis, and mitochondrial dysfunction in age‐associated cardiac dysfunction. In contrast to younger rats (6‐month of age), older rats (24‐month of age) exhibited severe cardiac ultrastructural defects, including deformed, fragmented mitochondria with high electron densities. Cardiomyocytes isolated from aged rats demonstrated increased reactive oxygen species (ROS), loss of mitochondrial membrane potential and altered mitochondrial dynamics, compared with younger controls. Moreover, mitochondrial defects were accompanied by mitochondrial and cytosolic Ca2+ ([Ca2+]i) overload, indicative of disrupted cellular Ca2+‐homeostasis. Interestingly, increased [Ca2+]i coincided with decreased phosphorylation of phospholamban (PLB) and contractility. Aged‐cardiomyocytes also displayed high Na+/Ca2+‐exchanger (NCX) activity and blood glucose levels compared with young‐controls. Interestingly, the protein level of SGLT2 was dramatically increased in the aged cardiomyocytes. Moreover, SGLT2 inhibition was sufficient to restore age‐associated defects in [Ca2+]i‐homeostasis, PLB phosphorylation, NCX activity and mitochondrial Ca2+‐loading. Hence, the present data suggest that deregulated SGLT2 during ageing disrupts mitochondrial function and cardiac contractility through a mechanism that impinges upon [Ca2+]i‐homeostasis. Our studies support the notion that interventions that modulate SGLT2‐activity can provide benefits in maintaining [Ca2+]i and cardiac function with advanced age.
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Affiliation(s)
- Yusuf Olgar
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Erkan Tuncay
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Sinan Degirmenci
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Deniz Billur
- Departments of Histology-Embriyology, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Rimpy Dhingra
- St. Boniface Hospital Albrechtsen Research Centre, Institute of Cardiovascular Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Lorrie Kirshenbaum
- St. Boniface Hospital Albrechtsen Research Centre, Institute of Cardiovascular Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Belma Turan
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
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10
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Olesen MA, Torres AK, Jara C, Murphy MP, Tapia-Rojas C. Premature synaptic mitochondrial dysfunction in the hippocampus during aging contributes to memory loss. Redox Biol 2020; 34:101558. [PMID: 32447261 PMCID: PMC7248293 DOI: 10.1016/j.redox.2020.101558] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/22/2020] [Accepted: 04/27/2020] [Indexed: 12/18/2022] Open
Abstract
Aging is a process characterized by cognitive impairment and mitochondrial dysfunction. In neurons, these organelles are classified as synaptic and non-synaptic mitochondria depending on their localization. Interestingly, synaptic mitochondria from the cerebral cortex accumulate more damage and are more sensitive to swelling than non-synaptic mitochondria. The hippocampus is fundamental for learning and memory, synaptic processes with high energy demand. However, it is unknown if functional differences are found in synaptic and non-synaptic hippocampal mitochondria; and whether this could contribute to memory loss during aging. In this study, we used 3, 6, 12 and 18 month-old (mo) mice to evaluate hippocampal memory and the function of both synaptic and non-synaptic mitochondria. Our results indicate that recognition memory is impaired from 12mo, whereas spatial memory is impaired at 18mo. This was accompanied by a differential function of synaptic and non-synaptic mitochondria. Interestingly, we observed premature dysfunction of synaptic mitochondria at 12mo, indicated by increased ROS generation, reduced ATP production and higher sensitivity to calcium overload, an effect that is not observed in non-synaptic mitochondria. In addition, at 18mo both mitochondrial populations showed bioenergetic defects, but synaptic mitochondria were prone to swelling than non-synaptic mitochondria. Finally, we treated 2, 11, and 17mo mice with MitoQ or Curcumin (Cc) for 5 weeks, to determine if the prevention of synaptic mitochondrial dysfunction could attenuate memory loss. Our results indicate that reducing synaptic mitochondrial dysfunction is sufficient to decrease age-associated cognitive impairment. In conclusion, our results indicate that age-related alterations in ATP produced by synaptic mitochondria are correlated with decreases in spatial and object recognition memory and propose that the maintenance of functional synaptic mitochondria is critical to prevent memory loss during aging. Hippocampus-dependent learning and memory are impaired with age, which correlated with synaptic mitochondrial dysfunction. Synaptic mitochondria fail before non-synaptic mitochondria, indicating premature synaptic mitochondrial damage in aging. Reducing synaptic mitochondrial dysfunction, with MitoQ or Curcumin, decrease age-associated hippocampal memory impairment. Age-related changes in ATP production of synaptic mitochondria correlated with decreased hippocampal memory. Maintenance of functional synaptic mitochondria is critical to prevent memory loss during aging.
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Affiliation(s)
- Margrethe A Olesen
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile
| | - Angie K Torres
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile
| | - Claudia Jara
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile
| | - Michael P Murphy
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Cheril Tapia-Rojas
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile.
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Pioglitazone and Deoxyribonucleoside Combination Treatment Increases Mitochondrial Respiratory Capacity in m.3243A>G MELAS Cybrid Cells. Int J Mol Sci 2020; 21:ijms21062139. [PMID: 32244971 PMCID: PMC7139379 DOI: 10.3390/ijms21062139] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/17/2020] [Accepted: 03/17/2020] [Indexed: 01/05/2023] Open
Abstract
The lack of effective treatments for mitochondrial disease has seen the development of new approaches, including those that aim to stimulate mitochondrial biogenesis to boost ATP generation above a critical disease threshold. Here, we examine the effects of the peroxisome proliferator-activated receptor γ (PPARγ) activator pioglitazone (PioG), in combination with deoxyribonucleosides (dNs), on mitochondrial biogenesis in cybrid cells containing >90% of the m.3243A>G mutation associated with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). PioG + dNs combination treatment increased mtDNA copy number and mitochondrial mass in both control (CON) and m.3243A>G (MUT) cybrids, with no adverse effects on cell proliferation. PioG + dNs also increased mtDNA-encoded transcripts in CON cybrids, but had the opposite effect in MUT cybrids, reducing the already elevated transcript levels. Steady-state levels of mature oxidative phosphorylation (OXPHOS) protein complexes were increased by PioG + dNs treatment in CON cybrids, but were unchanged in MUT cybrids. However, treatment was able to significantly increase maximal mitochondrial oxygen consumption rates and cell respiratory control ratios in both CON and MUT cybrids. Overall, these findings highlight the ability of PioG + dNs to improve mitochondrial respiratory function in cybrid cells containing the m.3243A>G MELAS mutation, as well as their potential for development into novel therapies to treat mitochondrial disease.
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Boczek T, Radzik T, Ferenc B, Zylinska L. The Puzzling Role of Neuron-Specific PMCA Isoforms in the Aging Process. Int J Mol Sci 2019; 20:ijms20246338. [PMID: 31888192 PMCID: PMC6941135 DOI: 10.3390/ijms20246338] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 12/10/2019] [Accepted: 12/13/2019] [Indexed: 01/02/2023] Open
Abstract
The aging process is a physiological phenomenon associated with progressive changes in metabolism, genes expression, and cellular resistance to stress. In neurons, one of the hallmarks of senescence is a disturbance of calcium homeostasis that may have far-reaching detrimental consequences on neuronal physiology and function. Among several proteins involved in calcium handling, plasma membrane Ca2+-ATPase (PMCA) is the most sensitive calcium detector controlling calcium homeostasis. PMCA exists in four main isoforms and PMCA2 and PMCA3 are highly expressed in the brain. The overall effects of impaired calcium extrusion due to age-dependent decline of PMCA function seem to accumulate with age, increasing the susceptibility to neurotoxic insults. To analyze the PMCA role in neuronal cells, we have developed stable transfected differentiated PC12 lines with down-regulated PMCA2 or PMCA3 isoforms to mimic age-related changes. The resting Ca2+ increased in both PMCA-deficient lines affecting the expression of several Ca2+-associated proteins, i.e., sarco/endoplasmic Ca2+-ATPase (SERCA), calmodulin, calcineurin, GAP43, CCR5, IP3Rs, and certain types of voltage-gated Ca2+ channels (VGCCs). Functional studies also demonstrated profound changes in intracellular pH regulation and mitochondrial metabolism. Moreover, modification of PMCAs membrane composition triggered some adaptive processes to counterbalance calcium overload, but the reduction of PMCA2 appeared to be more detrimental to the cells than PMCA3.
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Affiliation(s)
- Tomasz Boczek
- Department of Molecular Neurochemistry, Medical University, 92-215 Lodz, Poland; (T.B.); (T.R.); (B.F.)
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA 94304, USA
| | - Tomasz Radzik
- Department of Molecular Neurochemistry, Medical University, 92-215 Lodz, Poland; (T.B.); (T.R.); (B.F.)
| | - Bozena Ferenc
- Department of Molecular Neurochemistry, Medical University, 92-215 Lodz, Poland; (T.B.); (T.R.); (B.F.)
| | - Ludmila Zylinska
- Department of Molecular Neurochemistry, Medical University, 92-215 Lodz, Poland; (T.B.); (T.R.); (B.F.)
- Correspondence: ; Tel.: +48-42-272-5680
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Madreiter-Sokolowski CT, Waldeck-Weiermair M, Bourguignon MP, Villeneuve N, Gottschalk B, Klec C, Stryeck S, Radulovic S, Parichatikanond W, Frank S, Madl T, Malli R, Graier WF. Enhanced inter-compartmental Ca 2+ flux modulates mitochondrial metabolism and apoptotic threshold during aging. Redox Biol 2018; 20:458-466. [PMID: 30458321 PMCID: PMC6243020 DOI: 10.1016/j.redox.2018.11.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/02/2018] [Accepted: 11/06/2018] [Indexed: 01/02/2023] Open
Abstract
Background Senescence is characterized by a gradual decline in cellular functions, including changes in energy homeostasis and decreased proliferation activity. As cellular power plants, contributors to signal transduction, sources of reactive oxygen species (ROS) and executors of programmed cell death, mitochondria are in a unique position to affect aging-associated processes of cellular decline. Notably, metabolic activation of mitochondria is tightly linked to Ca2+ due to the Ca2+ -dependency of several enzymes in the Krebs cycle, however, overload of mitochondria with Ca2+ triggers cell death pathways. Consequently, a machinery of proteins tightly controls mitochondrial Ca2+ homeostasis as well as the exchange of Ca2+ between the different cellular compartments, including Ca2+ flux between mitochondria and the endoplasmic reticulum (ER). Methods In this study, we investigated age-related changes in mitochondrial Ca2+ homeostasis, mitochondrial-ER linkage and the activity of the main ROS production site, the mitochondrial respiration chain, in an in vitro aging model based on porcine aortic endothelial cells (PAECs), using high-resolution live cell imaging, proteomics and various molecular biological methods. Results We describe that in aged endothelial cells, increased ER-mitochondrial Ca2+ crosstalk occurs due to enhanced ER-mitochondrial tethering. The close functional inter-organelle linkage increases mitochondrial Ca2+ uptake and thereby the activity of the mitochondrial respiration, but also makes senescent cells more vulnerable to mitochondrial Ca2+-overload-induced cell death. Moreover, we identified the senolytic properties of the polyphenol resveratrol, triggering cell death via mitochondrial Ca2+ overload exclusively in senescent cells. Conclusion By unveiling aging-related changes in the inter-organelle tethering and Ca2+ communications we have advanced the understanding of endothelial aging and highlighted a potential basis to develop drugs specifically targeting senescent cells.
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Affiliation(s)
- Corina T Madreiter-Sokolowski
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; Department of Health Sciences and Technology, ETH Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland.
| | - Markus Waldeck-Weiermair
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | | | - Nicole Villeneuve
- Servier Research Institute, Cardiovascular Unit, 11 rue des Moulineaux, 92150 Suresnes, France
| | - Benjamin Gottschalk
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Christiane Klec
- Division of Oncology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
| | - Sarah Stryeck
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Snjezana Radulovic
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | | | - Saša Frank
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Tobias Madl
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Roland Malli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; BioTechMed, Graz, Austria
| | - Wolfgang F Graier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; BioTechMed, Graz, Austria.
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Tarpey MD, Amorese AJ, Balestrieri NP, Ryan TE, Schmidt CA, McClung JM, Spangenburg EE. Characterization and utilization of the flexor digitorum brevis for assessing skeletal muscle function. Skelet Muscle 2018; 8:14. [PMID: 29665848 PMCID: PMC5905177 DOI: 10.1186/s13395-018-0160-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 04/03/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The ability to assess skeletal muscle function and delineate regulatory mechanisms is essential to uncovering therapeutic approaches that preserve functional independence in a disease state. Skeletal muscle provides distinct experimental challenges due to inherent differences across muscle groups, including fiber type and size that may limit experimental approaches. The flexor digitorum brevis (FDB) possesses numerous properties that offer the investigator a high degree of experimental flexibility to address specific hypotheses. To date, surprisingly few studies have taken advantage of the FDB to investigate mechanisms regulating skeletal muscle function. The purpose of this study was to characterize and experimentally demonstrate the value of the FDB muscle for scientific investigations. METHODS First, we characterized the FDB phenotype and provide reference comparisons to skeletal muscles commonly used in the field. We developed approaches allowing for experimental assessment of force production, in vitro and in vivo microscopy, and mitochondrial respiration to demonstrate the versatility of the FDB. As proof-of principle, we performed experiments to alter force production or mitochondrial respiration to validate the flexibility the FDB affords the investigator. RESULTS The FDB is made up of small predominantly type IIa and IIx fibers that collectively produce less peak isometric force than the extensor digitorum longus (EDL) or soleus muscles, but demonstrates a greater fatigue resistance than the EDL. Unlike the other muscles, inherent properties of the FDB muscle make it amenable to multiple in vitro- and in vivo-based microscopy methods. Due to its anatomical location, the FDB can be used in cardiotoxin-induced muscle injury protocols and is amenable to electroporation of cDNA with a high degree of efficiency allowing for an effective means of genetic manipulation. Using a novel approach, we also demonstrate methods for assessing mitochondrial respiration in the FDB, which are comparable to the commonly used gastrocnemius muscle. As proof of principle, short-term overexpression of Pgc1α in the FDB increased mitochondrial respiration rates. CONCLUSION The results highlight the experimental flexibility afforded the investigator by using the FDB muscle to assess mechanisms that regulate skeletal muscle function.
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Affiliation(s)
- Michael D. Tarpey
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
| | - Adam J. Amorese
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
| | - Nicholas P. Balestrieri
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
| | - Terence E. Ryan
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
| | - Cameron A. Schmidt
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
| | - Joseph M. McClung
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834 USA
| | - Espen E. Spangenburg
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834 USA
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