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Hroudová J, Fišar Z. Alzheimer's disease approaches - Focusing on pathology, biomarkers and clinical trial candidates. Prog Neuropsychopharmacol Biol Psychiatry 2024; 134:111069. [PMID: 38917881 DOI: 10.1016/j.pnpbp.2024.111069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 06/19/2024] [Accepted: 06/19/2024] [Indexed: 06/27/2024]
Abstract
The strategy for the development of new drugs for Alzheimer's disease (AD) recognizes that an effective therapy requires early therapeutic intervention and a multifactorial approach that considers the individual initiators of AD development. Current knowledge of AD includes the understanding of pathophysiology, risk factors, biomarkers, and the evolving patterns of biomarker abnormalities. This knowledge is essential in identifying potential molecular targets for new drug development. This review summarizes promising AD drug candidates, many of which are currently in phase 2 or 3 clinical trials. New agents are classified according to the Common Alzheimer's Disease Research Ontology (CADRO). The main targets of new drugs for AD are processes related to amyloid beta and tau neurotoxicity, neurotransmission, inflammation, metabolism and bioenergetics, synaptic plasticity, and oxidative stress. These interventions are aimed at preventing disease onset and slowing or eliminating disease progression. The efficacy of pharmacotherapy may be enhanced by combining these drugs with other treatments, antioxidants, and dietary supplements. Ongoing research into AD pathophysiology, risk factors, biomarkers, and the dynamics of biomarker abnormalities may contribute to the understanding of AD and offer hope for effective therapeutic strategies in the near future.
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Affiliation(s)
- Jana Hroudová
- Department of Psychiatry, First Faculty of Medicine, Charles University and General University Hospital in Prague, Ke Karlovu 11, 120 00 Prague 2, Czech Republic.
| | - Zdeněk Fišar
- Department of Psychiatry, First Faculty of Medicine, Charles University and General University Hospital in Prague, Ke Karlovu 11, 120 00 Prague 2, Czech Republic
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Fišar Z. Linking the Amyloid, Tau, and Mitochondrial Hypotheses of Alzheimer's Disease and Identifying Promising Drug Targets. Biomolecules 2022; 12:1676. [PMID: 36421690 PMCID: PMC9687482 DOI: 10.3390/biom12111676] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/23/2022] [Accepted: 11/09/2022] [Indexed: 08/27/2023] Open
Abstract
Damage or loss of brain cells and impaired neurochemistry, neurogenesis, and synaptic and nonsynaptic plasticity of the brain lead to dementia in neurodegenerative diseases, such as Alzheimer's disease (AD). Injury to synapses and neurons and accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles are considered the main morphological and neuropathological features of AD. Age, genetic and epigenetic factors, environmental stressors, and lifestyle contribute to the risk of AD onset and progression. These risk factors are associated with structural and functional changes in the brain, leading to cognitive decline. Biomarkers of AD reflect or cause specific changes in brain function, especially changes in pathways associated with neurotransmission, neuroinflammation, bioenergetics, apoptosis, and oxidative and nitrosative stress. Even in the initial stages, AD is associated with Aβ neurotoxicity, mitochondrial dysfunction, and tau neurotoxicity. The integrative amyloid-tau-mitochondrial hypothesis assumes that the primary cause of AD is the neurotoxicity of Aβ oligomers and tau oligomers, mitochondrial dysfunction, and their mutual synergy. For the development of new efficient AD drugs, targeting the elimination of neurotoxicity, mutual potentiation of effects, and unwanted protein interactions of risk factors and biomarkers (mainly Aβ oligomers, tau oligomers, and mitochondrial dysfunction) in the early stage of the disease seems promising.
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Affiliation(s)
- Zdeněk Fišar
- Department of Psychiatry, First Faculty of Medicine, Charles University and General University Hospital in Prague, Ke Karlovu 11, 120 00 Prague, Czech Republic
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Dong ZH, Lin HY, Chen FL, Che XQ, Bi WK, Shi SL, Wang J, Gao L, He Z, Zhao JJ. Berberine improves intralipid-induced insulin resistance in murine. Acta Pharmacol Sin 2021; 42:735-743. [PMID: 32770172 PMCID: PMC8115075 DOI: 10.1038/s41401-020-0493-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/26/2020] [Indexed: 12/13/2022] Open
Abstract
Insulin resistance (IR) is a major metabolic risk factor even before the onset of hyperglycemia. Recently, berberine (BBR) is found to improve hyperglycemia and IR. In this study, we investigated whether BBR could improve IR independent of hyperglycemia. Acute insulin-resistant state was induced in rats by systemic infusion of intralipid (6.6%). BBR was administered via different delivery routes before or after the beginning of a 2-h euglycemic-hyperinsulinemic clamp. At the end of experiment, rats were sacrificed, gastrocnemius muscle was collected for detecting mitochondrial swelling, phosphorylation of Akt and AMPK, as well as the mitochondrial permeability regulator cyclophilin D (CypD) protein expression. We showed that BBR administration markedly ameliorated intralipid-induced IR without affecting blood glucose, which was accompanied by alleviated mitochondrial swelling in skeletal muscle. We used human skeletal muscle cells (HSMCs), AML12 hepatocytes, human umbilical vein endothelial cells, and CypD knockout mice to investigate metabolic and molecular alternations. In either HSMCs or AML12 hepatocytes, BBR (5 μM) abolished palmitate acid (PA)-induced increase of CypD protein levels. In CypD-deficient mice, intralipid-induced IR was greatly attenuated and the beneficial effect of BBR was diminished. Furthermore, we demonstrated that the inhibitory effect of BBR on intralipid-induced IR was mainly mediated by skeletal muscle, but not by intestine, liver, or microvasculature; BBR administration suppressed intralipid-induced upregulation of CypD expression in skeletal muscle. These results suggest that BBR alleviates intralipid-induced IR, which is related to the inhibition of CypD protein expression in skeletal muscle.
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Affiliation(s)
- Zhen-Hua Dong
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Cheeloo College of Medicine, Shandong University, Ji-nan, 250000, China
- Department of Endocrinology, Ji-nan Central Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250000, China
| | - Hai-Yan Lin
- Department of Health Management Center, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250000, China
| | - Fu-Lian Chen
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
| | - Xiao-Qi Che
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Cheeloo College of Medicine, Shandong University, Ji-nan, 250000, China
| | - Wen-Kai Bi
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Cheeloo College of Medicine, Shandong University, Ji-nan, 250000, China
| | - Shu-Long Shi
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
| | - Jing Wang
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China
- Cheeloo College of Medicine, Shandong University, Ji-nan, 250000, China
| | - Ling Gao
- Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University and Shandong Academy of Medical Sciences, Ji-nan, 250000, China.
| | - Zhao He
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China.
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China.
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China.
- Cheeloo College of Medicine, Shandong University, Ji-nan, 250000, China.
| | - Jia-Jun Zhao
- Department of Endocrinology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Ji-nan, 250021, China.
- Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China.
- Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Ji-nan, 250021, China.
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Li T, Xu J, Qin X, Hou Z, Guo Y, Liu Z, Wu J, Zheng H, Zhang X, Gao F. Glucose oxidation positively regulates glucose uptake and improves cardiac function recovery after myocardial reperfusion. Am J Physiol Endocrinol Metab 2017; 313:E577-E585. [PMID: 28325730 DOI: 10.1152/ajpendo.00014.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 01/31/2023]
Abstract
Myocardial reperfusion decreases glucose oxidation and uncouples glucose oxidation from glycolysis. Therapies that increase glucose oxidation lessen myocardial ischemia-reperfusion (I/R) injury. However, the regulation of glucose uptake during reperfusion remains poorly understood. We found that glucose uptake was remarkably diminished in the myocardium following reperfusion in Sprague-Dawley rats as detected by 18F-labeled and fluorescent-labeled glucose analogs, even though GLUT1 was upregulated by threefold and GLUT4 translocation remained unchanged compared with those of sham-treated rats. The decreased glucose uptake was accompanied by suppressed glucose oxidation. Interestingly, stimulating glucose oxidation by inhibition of pyruvate dehydrogenase kinase 4 (PDK4), a rate-limiting enzyme for glucose oxidation, increased glucose uptake and alleviated I/R injury. In vitro data in neonatal myocytes showed that PDK4 overexpression decreased glucose uptake, whereas its knockdown increased glucose uptake, suggesting that PDK4 has a role in regulating glucose uptake. Moreover, inhibition of PDK4 increased myocardial glucose uptake with concomitant enhancement of cardiac insulin sensitivity following myocardial I/R. These results showed that the suppressed glucose oxidation mediated by PDK4 contributes to the reduced glucose uptake in the myocardium following reperfusion, and enhancement of glucose uptake exerts cardioprotection. The findings suggest that stimulating glucose oxidation via PDK4 could be an efficient approach to improve recovery from myocardial I/R injury.
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Affiliation(s)
- Tingting Li
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Jie Xu
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Xinghua Qin
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Zuoxu Hou
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Yongzheng Guo
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Zhenhua Liu
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Jianjiang Wu
- Department of Anesthesiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Hong Zheng
- Department of Anesthesiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Xing Zhang
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Feng Gao
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
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Rieusset J. Mitochondria-associated membranes (MAMs): An emerging platform connecting energy and immune sensing to metabolic flexibility. Biochem Biophys Res Commun 2017. [PMID: 28647358 DOI: 10.1016/j.bbrc.2017.06.097] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Living organisms have the capacity to sense both nutrients and immune signals in order to adapt their metabolism to the needs, and both metabolic inflexibility and exacerbated immune responses are associated with metabolic diseases. Over the past decade, mitochondria emerged as key nutrient and immune sensors regulating numerous signalling pathways, and mitochondria dysfunction has been extensively implicated in metabolic diseases. Interestingly, mitochondria interact physically and functionally with the endoplasmic reticulum (ER, in contact sites named mitochondria-associated membranes (MAMs), in order to exchange metabolites and calcium and regulate cellular homeostasis. Emerging evidences suggest that MAMs provide a platform for hormone and nutrient signalling pathways and for innate immune responses, then regulating mitochondrial bioenergetics and apoptosis. Here, I thus propose the concept that MAMs could be attractive nutrient and immune sensors that regulate mitochondria physiology in order to adapt metabolism and cell fate, and that organelle miscommunication could be involved in the metabolic inflexibility and the pro-inflammatory status associated with metabolic diseases.
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Affiliation(s)
- Jennifer Rieusset
- Laboratoire CarMeN, INSERM U1060, INRA U1235, Université Claude Bernard Lyon1, INSA-Lyon, F-69600 Oullins, France.
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Rieusset J. Endoplasmic reticulum-mitochondria calcium signaling in hepatic metabolic diseases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:865-876. [PMID: 28064001 DOI: 10.1016/j.bbamcr.2017.01.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 12/21/2016] [Accepted: 01/02/2017] [Indexed: 02/07/2023]
Abstract
The liver plays a central role in glucose homeostasis, and both metabolic inflexibility and insulin resistance predispose to the development of hepatic metabolic diseases. Mitochondria and endoplasmic reticulum (ER), which play a key role in the control of hepatic metabolism, also interact at contact points defined as mitochondria-associated membranes (MAM), in order to exchange metabolites and calcium (Ca2+) and regulate cellular homeostasis and signaling. Here, we overview the role of the liver in the control of glucose homeostasis, mainly focusing on the independent involvement of mitochondria, ER and Ca2+ signaling in both healthy and pathological contexts. Then we focus on recent data highlighting MAM as important hubs for hormone and nutrient signaling in the liver, thus adapting mitochondria physiology and cellular metabolism to energy availability. Lastly, we discuss how chronic ER-mitochondria miscommunication could participate to hepatic metabolic diseases, pointing MAM interface as a potential therapeutic target for metabolic disorders. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Jennifer Rieusset
- INSERM UMR-1060, CarMeN Laboratory, Lyon 1 University, INRA U1397, F-69921 Oullins, France.
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Aliou Y, Liao MC, Zhao XP, Chang SY, Chenier I, Ingelfinger JR, Zhang SL. Post-weaning high-fat diet accelerates kidney injury, but not hypertension programmed by maternal diabetes. Pediatr Res 2016; 79:416-24. [PMID: 26571223 DOI: 10.1038/pr.2015.236] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 08/24/2015] [Indexed: 12/31/2022]
Abstract
BACKGROUND The aim of this study was to establish the underlying mechanisms by which a post-weaning high-fat diet (HFD) accelerates the perinatal programming of kidney injury occurring in the offspring of diabetic mothers. METHODS Male mice, offspring of nondiabetic and diabetic dams were fed with normal diet (ND) or HFD from 4 to 20 wk of age. Rat renal proximal tubular cells were used in vitro. RESULTS On ND, the offspring of dams with severe maternal diabetes had an intrauterine growth restriction (IUGR) phenotype and developed mild hypertension and evidence of kidney injury in adulthood. Exposing the IUGR offspring to HFD resulted in rapid weight gain, catch-up growth, and later to profound kidney injury with activation of renal TGFβ1 and collagen type IV expression, increased oxidative stress, and enhanced renal lipid deposition, but not systemic hypertension. Given our data, we speculate that HFD or free fatty acids may accelerate the process of perinatal programming of kidney injury, via increased CD36 and fatty acid-binding protein 4 expression, which may target reactive oxygen species, nuclear factor-kappa B, and TGFβ1 signaling in vivo and in vitro. CONCLUSION Early postnatal exposure to overnutrition with a HFD increases the risk of development of kidney injury, but not hypertension, in IUGR offspring of dams with maternal diabetes.
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Affiliation(s)
- Yessoufou Aliou
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Min-Chun Liao
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Xin-Ping Zhao
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Shiao-Ying Chang
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Isabelle Chenier
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Julie R Ingelfinger
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School Boston, Boston, Massachusetts
| | - Shao-Ling Zhang
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
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Hagve M, Gjessing PF, Fuskevåg OM, Larsen TS, Irtun Ø. Skeletal muscle mitochondria exhibit decreased pyruvate oxidation capacity and increased ROS emission during surgery-induced acute insulin resistance. Am J Physiol Endocrinol Metab 2015; 308:E613-20. [PMID: 25670828 DOI: 10.1152/ajpendo.00459.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 02/04/2015] [Indexed: 01/01/2023]
Abstract
Development of acute insulin resistance represents a negative factor after surgery, but the underlying mechanisms are not fully understood. We investigated the postoperative changes in insulin sensitivity, mitochondrial function, enzyme activities, and release of reactive oxygen species (ROS) in skeletal muscle and liver in pigs on the 2nd postoperative day after major abdominal surgery. Peripheral and hepatic insulin sensitivity were assessed by D-[6,6-²H₂]glucose infusion and hyperinsulinemic euglycemic step clamping. Surgical trauma elicited a decline in peripheral insulin sensitivity (∼34%, P<0.01), whereas hepatic insulin sensitivity remained unchanged. Intramyofibrillar (IFM) and subsarcolemma mitochondria (SSM) isolated from skeletal muscle showed a postoperative decline in ADP-stimulated respiration (V(ADP)) for pyruvate (∼61%, P<0.05, and ∼40%, P<0.001, respectively), whereas V(ADP) for glutamate and palmitoyl-L-carnitine (PC) was unchanged. Mitochondrial leak respiration with PC was increased in SSM (1.9-fold, P<0.05) and IFM (2.5-fold, P<0.05), indicating FFA-induced uncoupling. The activity of the pyruvate dehydrogenase complex (PDC) was reduced (∼32%, P<0.01) and positively correlated to the decline in peripheral insulin sensitivity (r=0.748, P<0.05). All other mitochondrial enzyme activities were unchanged. No changes in mitochondrial function in liver were observed. Mitochondrial H₂O₂ and O₂·⁻ emission was measured spectrofluorometrically, and H₂O₂ was increased in SSM, IFM, and liver mitochondria (∼2.3-, ∼2.5-, and ∼2.3-fold, respectively, all P<0.05). We conclude that an impairment in skeletal muscle mitochondrial PDC activity and pyruvate oxidation capacity arises in the postoperative phase along with increased ROS emission, suggesting a link between mitochondrial function and development of acute postoperative insulin resistance.
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Affiliation(s)
- Martin Hagve
- Laboratory of Surgical Research, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway; Cardiovascular Research Group, Department of Medical Biology, UiT The Arctic University of Norway, Tromsø, Norway;
| | - Petter Fosse Gjessing
- Laboratory of Surgical Research, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway; Department of Digestive Surgery, University Hospital of North Norway, Tromsø, Norway; and
| | - Ole Martin Fuskevåg
- Department of Laboratory Medicine, Division of Diagnostic Services, University Hospital of North Norway, Tromsø, Norway
| | - Terje S Larsen
- Cardiovascular Research Group, Department of Medical Biology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Øivind Irtun
- Laboratory of Surgical Research, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway; Department of Digestive Surgery, University Hospital of North Norway, Tromsø, Norway; and
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Opening of the mitochondrial permeability transition pore links mitochondrial dysfunction to insulin resistance in skeletal muscle. Mol Metab 2013; 3:124-34. [PMID: 24634818 DOI: 10.1016/j.molmet.2013.11.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 11/14/2013] [Indexed: 12/14/2022] Open
Abstract
Insulin resistance is associated with mitochondrial dysfunction, but the mechanism by which mitochondria inhibit insulin-stimulated glucose uptake into the cytoplasm is unclear. The mitochondrial permeability transition pore (mPTP) is a protein complex that facilitates the exchange of molecules between the mitochondrial matrix and cytoplasm, and opening of the mPTP occurs in response to physiological stressors that are associated with insulin resistance. In this study, we investigated whether mPTP opening provides a link between mitochondrial dysfunction and insulin resistance by inhibiting the mPTP gatekeeper protein cyclophilin D (CypD) in vivo and in vitro. Mice lacking CypD were protected from high fat diet-induced glucose intolerance due to increased glucose uptake in skeletal muscle. The mitochondria in CypD knockout muscle were resistant to diet-induced swelling and had improved calcium retention capacity compared to controls; however, no changes were observed in muscle oxidative damage, insulin signaling, lipotoxic lipid accumulation or mitochondrial bioenergetics. In vitro, we tested 4 models of insulin resistance that are linked to mitochondrial dysfunction in cultured skeletal muscle cells including antimycin A, C2-ceramide, ferutinin, and palmitate. In all models, we observed that pharmacological inhibition of mPTP opening with the CypD inhibitor cyclosporin A was sufficient to prevent insulin resistance at the level of insulin-stimulated GLUT4 translocation to the plasma membrane. The protective effects of mPTP inhibition on insulin sensitivity were associated with improved mitochondrial calcium retention capacity but did not involve changes in insulin signaling both in vitro and in vivo. In sum, these data place the mPTP at a critical intersection between alterations in mitochondrial function and insulin resistance in skeletal muscle.
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Key Words
- ANT, adenine nucleotide translocator
- BKA, bongkrekic acid
- CSA, cyclosporin A
- CYPD, cyclophilin D
- Cyclophilin D
- DAG, diacylglycerol
- ETC, electron transport chain
- FFA, free fatty acid
- Glucose
- HFD, high fat diet
- HK2, hexokinase 2
- Insulin resistance
- KO, knockout
- LFD, low fat diet
- MCAD, medium chain acyl-CoA dehydrogenase
- MHC, myosin heavy chain
- MIRKO, muscle insulin receptor knockout
- MPTP, mitochondrial permeability transition pore
- Mitochondrial dysfunction
- Mitochondrial permeability transition pore
- MnSOD, mitochondrial manganese superoxide dismutase
- O2•, superoxide
- OXPHOS, oxidative phosphorylation
- PDH, pyruvate dehydrogenase
- PDHa, active PDH
- PDHt, total PDH
- PM, plasma membrane
- Rg′, rate of glucose transport
- Skeletal muscle
- TBARS, thiobarbituric acid reactive substances
- TEM, transmission electron microscopy
- VDAC, voltage-dependent anion channel
- WT, wild type
- [3H]-2-DOG, [3H]-2-deoxyglucose
- β-HAD, β-hydroxyacyl-CoA dehydrogenase
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Mittendorfer B. Origins of metabolic complications in obesity: adipose tissue and free fatty acid trafficking. Curr Opin Clin Nutr Metab Care 2011; 14:535-41. [PMID: 21849896 PMCID: PMC3711689 DOI: 10.1097/mco.0b013e32834ad8b6] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Obesity is associated with a number of serious medical complications that are risk factors for cardiovascular disease (e.g., insulin resistance, dyslipidemia, and liver fat accumulation). Alterations in fatty acid trafficking, both between tissues and within cells, represent a key feature in the pathophysiology of the metabolic complications in obese patients. The ways by which fatty acid 're-routing' may affect metabolic function are summarized in this article. RECENT FINDINGS Ectopic fat accumulation (i.e., fat accumulation in nonadipose tissues) appears to be a key feature distinguishing metabolically healthy from metabolically abnormal patients. This observation has led to the belief that an imbalance in fatty acid trafficking away from adipose tissue toward nonadipose tissues is a primary cause for the development of metabolic alterations in obese patients. More recently, however, it has become apparent that fatty acid trafficking within nonadipose tissues cells (i.e., toward storage - in the form of triglycerides - and oxidation) may be equally important in determining a person's risk for development of metabolic disease. SUMMARY The pathophysiology of the metabolic alterations associated with obesity is probably multifactorial within a complex network of coordinated physiological responses. Only through the integration of multiple concepts, will it be possible to further our understanding in this area and to help prevent the metabolic alterations associated with obesity.
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Affiliation(s)
- Bettina Mittendorfer
- Division of Geriatrics and Nutritional Sciences, Washington University School of Medicine, St. Louis, Missouri, USA.
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