1
|
Ryan TE, Torres MJ, Lin CT, Clark AH, Brophy PM, Smith CA, Smith CD, Morris EM, Thyfault JP, Neufer PD. High-dose atorvastatin therapy progressively decreases skeletal muscle mitochondrial respiratory capacity in humans. JCI Insight 2024; 9:e174125. [PMID: 38385748 DOI: 10.1172/jci.insight.174125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 01/09/2024] [Indexed: 02/23/2024] Open
Abstract
BACKGROUNDWhile the benefits of statin therapy on atherosclerotic cardiovascular disease are clear, patients often experience mild to moderate skeletal myopathic symptoms, the mechanism for which is unknown. This study investigated the potential effect of high-dose atorvastatin therapy on skeletal muscle mitochondrial function and whole-body aerobic capacity in humans.METHODSEight overweight (BMI, 31.9 ± 2.0) but otherwise healthy sedentary adults (4 females, 4 males) were studied before (day 0) and 14, 28, and 56 days after initiating atorvastatin (80 mg/d) therapy.RESULTSMaximal ADP-stimulated respiration, measured in permeabilized fiber bundles from muscle biopsies taken at each time point, declined gradually over the course of atorvastatin treatment, resulting in > 30% loss of skeletal muscle mitochondrial oxidative phosphorylation capacity by day 56. Indices of in vivo muscle oxidative capacity (via near-infrared spectroscopy) decreased by 23% to 45%. In whole muscle homogenates from day 0 biopsies, atorvastatin inhibited complex III activity at midmicromolar concentrations, whereas complex IV activity was inhibited at low nanomolar concentrations.CONCLUSIONThese findings demonstrate that high-dose atorvastatin treatment elicits a striking progressive decline in skeletal muscle mitochondrial respiratory capacity, highlighting the need for longer-term dose-response studies in different patient populations to thoroughly define the effect of statin therapy on skeletal muscle health.FUNDINGNIH R01 AR071263.
Collapse
Affiliation(s)
- Terence E Ryan
- East Carolina Diabetes and Obesity Institute and
- Department of Physiology, Brody School of Medicine Greenville, North Carolina, USA
| | - Maria J Torres
- East Carolina Diabetes and Obesity Institute and
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute and
- Department of Physiology, Brody School of Medicine Greenville, North Carolina, USA
| | | | | | - Cheryl A Smith
- East Carolina Diabetes and Obesity Institute and
- Department of Physiology, Brody School of Medicine Greenville, North Carolina, USA
| | - Cody D Smith
- East Carolina Diabetes and Obesity Institute and
- Department of Physiology, Brody School of Medicine Greenville, North Carolina, USA
| | | | - John P Thyfault
- Cell Biology and Physiology and
- Kansas University Diabetes Institute and Department of Internal Medicine, Division of Endocrinology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute and
- Department of Physiology, Brody School of Medicine Greenville, North Carolina, USA
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, Greenville, North Carolina, USA
| |
Collapse
|
2
|
Pal A, Lin CT, Boykov I, Benson E, Kidd G, Fisher-Wellman KH, Neufer PD, Shaikh SR. High Fat Diet-Induced Obesity Dysregulates Splenic B Cell Mitochondrial Activity. Nutrients 2023; 15:4807. [PMID: 38004202 PMCID: PMC10675399 DOI: 10.3390/nu15224807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/07/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Diet-induced obesity impairs mitochondrial respiratory responses in tissues that are highly metabolically active, such as the heart. However, less is known about the impact of obesity on the respiratory activity of specific cell types, such as splenic B cells. B cells are of relevance, as they play functional roles in obesity-induced insulin resistance, inflammation, and responses to infection. Here, we tested the hypothesis that high-fat-diet (HFD)-induced obesity could impair the mitochondrial respiration of intact and permeabilized splenic CD19+ B cells isolated from C57BL/6J mice and activated ex vivo with lipopolysaccharide (LPS). High-resolution respirometry was used with intact and permeabilized cells. To reveal potential mechanistic targets by which HFD-induced obesity dysregulates B cell mitochondria, we conducted proteomic analyses and 3D serial block face scanning electron microscopy (SBFEM). High-resolution respirometry revealed that intact LPS-stimulated B cells of obese mice, relative to controls, displayed lower ATP-linked, as well as maximal uncoupled, respiration. To directly investigate mitochondrial function, we used permeabilized LPS-stimulated B cells, which displayed increased H2O2 emission and production with obesity. We also examined oxidative phosphorylation efficiency simultaneously, which revealed that oxygen consumption and ATP production were decreased in LPS-stimulated B cells with obesity relative to controls. Despite minimal changes in total respiratory complex abundance, in LPS-stimulated B cells of obese mice, three of the top ten most downregulated proteins were all accessory subunits of respiratory complex I. SBFEM showed that B cells of obese mice, compared to controls, underwent no change in mitochondrial cristae integrity but displayed increased mitochondrial volume that was linked to bioenergetic function. Collectively, these results establish a proof of concept that HFD-induced obesity dysregulates the mitochondrial bioenergetic metabolism of activated splenic B cells.
Collapse
Affiliation(s)
- Anandita Pal
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA; (C.-T.L.); (I.B.); (K.H.F.-W.)
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Ilya Boykov
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA; (C.-T.L.); (I.B.); (K.H.F.-W.)
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Emily Benson
- 3D-EM Ultrastructural Imaging and Computation Core, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44106, USA; (E.B.); (G.K.)
| | - Grahame Kidd
- 3D-EM Ultrastructural Imaging and Computation Core, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44106, USA; (E.B.); (G.K.)
| | - Kelsey H. Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA; (C.-T.L.); (I.B.); (K.H.F.-W.)
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - P. Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA; (C.-T.L.); (I.B.); (K.H.F.-W.)
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| |
Collapse
|
3
|
Iguidbashian J, Lun Z, Bata K, King RW, Gunn-Sandell L, Crosby D, Stoebner K, Tharp D, Lin CT, Cumbler E, Wiler J, Yi J. Novel Electronic Health Records-Based Consultation Workflow Improves Time to Operating Room for Vascular Surgery Patients in an Acute Setting. Ann Vasc Surg 2023; 97:139-146. [PMID: 37495093 DOI: 10.1016/j.avsg.2023.07.101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/04/2023] [Accepted: 07/11/2023] [Indexed: 07/28/2023]
Abstract
BACKGROUND Inefficient clinical workflows can have downstream effects of increased costs, poor resource utilization, and worse patient outcomes. The surgical consultation process can be complex with unclear communication, potentially delaying care for patients requiring time-sensitive intervention in an acute setting. A novel electronic health records (EHR)-based workflow was implemented to improve the consultation process. After implementation, we assessed the impact of this initiative in patients requiring vascular surgery consultation. METHODS An EHR-driven consultation workflow was implemented at a single institution, standardizing the process across all consulting services. This order-initiated workflow automated notification to clinicians of consult requests, communication of patient data, patient addition to consultants' lists, and tracking consult completion. Preimplementation (1/1/2020-1/31/2022) and postimplementation (2/1/2022-12/4/2022) vascular surgery consultation cohorts were compared to evaluate the impact of this initiative on timeliness of care. RESULTS There were 554 inpatient vascular surgery consultations (255 preimplementation and 299 postimplementation); 45 and 76 consults required surgery before and after implementation, respectively. The novel workflow resulted in placement of a consult note 32 min faster than preimplementation (preimplementation: 462 min, postimplementation: 430 min, P = 0.001) for all vascular surgery consults. Furthermore, vascular surgery patients with ASA class III or IV status requiring an urgent or emergent operation were transported to the operating room 63.3% faster after implementation of the workflow (preimplementation: 284 min, postimplementation: 180 min, P = 0.02). There were no differences in procedure duration, postoperative disposition, or intraoperative complication rates. CONCLUSIONS We implemented a novel workflow utilizing the EHR to standardize and automate the consultation process in the acute inpatient setting. This institutional initiative significantly improved timeliness of care for vascular surgery patients, including decreased time to operation. Innovations such as this can be further disseminated across shared EHR platforms across institutions, representing a powerful tool to increase the value of care in vascular surgery and healthcare overall.
Collapse
Affiliation(s)
- John Iguidbashian
- Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO.
| | - Zhixin Lun
- Department of Biostatistics, Center of Innovative Design and Analysis, Colorado School of Public Health, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Kyle Bata
- Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Robert W King
- Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Lauren Gunn-Sandell
- Department of Biostatistics, Center of Innovative Design and Analysis, Colorado School of Public Health, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Derek Crosby
- Division of Vascular Medicine, University of Colorado Health, Aurora, CO
| | - Kristin Stoebner
- Division of Vascular Medicine, University of Colorado Health, Aurora, CO
| | - David Tharp
- Division of Vascular Medicine, University of Colorado Health, Aurora, CO
| | - C T Lin
- Department of Medicine, University of Colorado, Aurora, CO
| | - Ethan Cumbler
- Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO; Department of Medicine, University of Colorado, Aurora, CO
| | - Jennifer Wiler
- Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jeniann Yi
- Division of Vascular Surgery and Endovascular Therapy, University of Colorado Anschutz Medical Campus, Aurora, CO
| |
Collapse
|
4
|
Lin YC, Liao TC, Lin CT, Jeng LB, Yang HR, Hsu CH, Lin WC, Wu CF, Yeh CC. Salvage surgeries for splanchnic artery aneurysms after failed endovascular therapy - case series. Int J Surg 2023:01279778-990000000-00362. [PMID: 37204471 PMCID: PMC10389617 DOI: 10.1097/js9.0000000000000442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/01/2023] [Indexed: 05/20/2023]
Abstract
INTRODUCTION Splanchnic arterial aneurysms are a rare but potentially lethal disease with a mortality rate of more than 10% after rupture. Endovascular therapy is the first-line treatment for splanchnic aneurysms. However, appropriate management for splanchnic aneurysms after failed endovascular therapy remained inconclusive. MATERIALS AND METHODS A retrospective review was performed for consecutive patients (from 2019 to 2022) who underwent salvage surgeries for splanchnic artery aneurysms following failed endovascular therapy. We defined failed endovascular therapy as technical infeasibility to apply endovascular therapy, incomplete exclusion of the aneurysm, or the incomplete resolution of preoperative aneurysm-associated complications. Salvage operations included aneurysmectomy with vascular reconstruction and partial aneurysmectomy with directly closing of bleeders from the intraluminal space of the aneurysms. RESULTS Seventy-three patients received endovascular therapies for splanchnic aneurysms, and 13 failed endovascular trials. We performed salvage surgeries for five patients and enrolled them in this study, including four false aneurysms of the celiac or superior mesenteric arteries and a true aneurysm of the common hepatic artery. The causes of failed endovascular therapy included coil migration, insufficient space for safely deploying the covered stent, a persistent mass effect from the post-embolized aneurysm, or infeasibility for catheter cannulation. The mean hospital stay was nine days (mean±SD, 8.8±1.6 d), with no one suffering 90-day surgical morbidity and mortality, and all patients getting symptoms improvement. During the follow-up period (mean±SD, 24±10 mo), one patient suffered a small residual asymptomatic celiac artery aneurysm (8 mm in diameter) and was treated conservatively due to underlying liver cirrhosis. CONCLUSION Surgical management is a feasible, effective, and safe alternative for splanchnic aneurysms after failed endovascular therapy.
Collapse
Affiliation(s)
- Yi-Chun Lin
- School of Medicine, China Medical University, Taichung, Taiwan
- Department of Medical Education, Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Tzu-Chi Liao
- School of Medicine, China Medical University, Taichung, Taiwan
- Department of Medical Education, Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Chien-Te Lin
- Department of Surgery, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Long-Bin Jeng
- School of Medicine, China Medical University, Taichung, Taiwan
- Department of Surgery, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Horng-Ren Yang
- Department of Surgery, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Chung-Ho Hsu
- Department of Medicine, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Wei-Ching Lin
- Department of Medical Imaging, China Medical University Hospital, Taichung, Taiwan
- Department of Biomedical Imaging and Radiological Science, School of Medicine, China Medical University, Taichung, Taiwan
| | - Ching-Feng Wu
- Department of Surgery, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Chun-Chieh Yeh
- School of Medicine, China Medical University, Taichung, Taiwan
- Department of Surgery, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Department of Surgery, Asian University Hospital, Taichung, Taiwan
| |
Collapse
|
5
|
Abstract
Fuzzy membership is an effective approach used in twin support vector machines (SVMs) to reduce the effect of noise and outliers in classification problems. Fuzzy twin SVMs (TWSVMs) assign membership weights to reduce the effect of outliers, however, it ignores the positioning of the input data samples and hence fails to distinguish between support vectors and noise. To overcome this issue, intuitionistic fuzzy TWSVM combined the concept of intuitionistic fuzzy number with TWSVMs to reduce the effect of outliers and distinguish support vectors from noise. Despite these benefits, TWSVMs and intuitionistic fuzzy TWSVMs still suffer from some drawbacks as: 1) the local neighborhood information is ignored among the data points and 2) they solve quadratic programming problems (QPPs), which is computationally inefficient. To overcome these issues, we propose a novel intuitionistic fuzzy weighted least squares TWSVMs for classification problems. The proposed approach uses local neighborhood information among the data points and also uses both membership and nonmembership weights to reduce the effect of noise and outliers. The proposed approach solves a system of linear equations instead of solving the QPPs which makes the model more efficient. We evaluated the proposed intuitionistic fuzzy weighted least squares TWSVMs on several benchmark datasets to show the efficiency of the proposed model. Statistical analysis is done to quantify the results statistically. As an application, we used the proposed model for the diagnosis of Schizophrenia disease.
Collapse
|
6
|
Tang Y, Zong H, Kwon H, Qiu Y, Pessin JB, Wu L, Buddo KA, Boykov I, Schmidt CA, Lin CT, Neufer PD, Schwartz GJ, Kurland IJ, Pessin J. TIGAR deficiency enhances skeletal muscle thermogenesis by increasing neuromuscular junction cholinergic signaling. eLife 2022; 11:73360. [PMID: 35254259 PMCID: PMC8947760 DOI: 10.7554/elife.73360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 03/02/2022] [Indexed: 12/03/2022] Open
Abstract
Cholinergic and sympathetic counter-regulatory networks control numerous physiological functions, including learning/memory/cognition, stress responsiveness, blood pressure, heart rate, and energy balance. As neurons primarily utilize glucose as their primary metabolic energy source, we generated mice with increased glycolysis in cholinergic neurons by specific deletion of the fructose-2,6-phosphatase protein TIGAR. Steady-state and stable isotope flux analyses demonstrated increased rates of glycolysis, acetyl-CoA production, acetylcholine levels, and density of neuromuscular synaptic junction clusters with enhanced acetylcholine release. The increase in cholinergic signaling reduced blood pressure and heart rate with a remarkable resistance to cold-induced hypothermia. These data directly demonstrate that increased cholinergic signaling through the modulation of glycolysis has several metabolic benefits particularly to increase energy expenditure and heat production upon cold exposure.
Collapse
Affiliation(s)
- Yan Tang
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Haihong Zong
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Hyokjoon Kwon
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Yunping Qiu
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Jacob B Pessin
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Licheng Wu
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Katherine A Buddo
- Department of Physiology, East Carolina University, Greenville, United States
| | - Ilya Boykov
- Department of Physiology, East Carolina University, Greenville, United States
| | - Cameron A Schmidt
- Department of Physiology, East Carolina University, Greenville, United States
| | - Chien-Te Lin
- Department of Physiology, East Carolina University, Greenville, United States
| | - P Darrell Neufer
- Department of Physiology, East Carolina University, Greenville, United States
| | - Gary J Schwartz
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Irwin J Kurland
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| | - Jeffrey Pessin
- Department of Medicine, Albert Einstein College of Medicine, Bronx, United States
| |
Collapse
|
7
|
Pereyra AS, Lin CT, Sanchez DM, Laskin J, Spangenburg EE, Neufer PD, Fisher-Wellman K, Ellis JM. Skeletal muscle undergoes fiber type metabolic switch without myosin heavy chain switch in response to defective fatty acid oxidation. Mol Metab 2022; 59:101456. [PMID: 35150906 PMCID: PMC8898976 DOI: 10.1016/j.molmet.2022.101456] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/27/2022] [Accepted: 02/03/2022] [Indexed: 11/20/2022] Open
Abstract
Objective Skeletal muscle is a heterogeneous and dynamic tissue that adapts to functional demands and substrate availability by modulating muscle fiber size and type. The concept of muscle fiber type relates to its contractile (slow or fast) and metabolic (glycolytic or oxidative) properties. Here, we tested whether disruptions in muscle oxidative catabolism are sufficient to prompt parallel adaptations in energetics and contractile protein composition. Methods Mice with defective mitochondrial long-chain fatty acid oxidation (mLCFAO) in the skeletal muscle due to loss of carnitine palmitoyltransferase 2 (Cpt2Sk−/−) were used to model a shift in muscle macronutrient catabolism. Glycolytic and oxidative muscles of Cpt2Sk−/− mice and control littermates were compared for the expression of energy metabolism-related proteins, mitochondrial respiratory capacity, and myosin heavy chain isoform composition. Results Differences in bioenergetics and macronutrient utilization in response to energy demands between control muscles were intrinsic to the mitochondria, allowing for a clear distinction of muscle types. Loss of CPT2 ablated mLCFAO and resulted in mitochondrial biogenesis occurring most predominantly in oxidative muscle fibers. The metabolism-related proteomic signature of Cpt2Sk−/− oxidative muscle more closely resembled that of glycolytic muscle than of control oxidative muscle. Respectively, intrinsic substrate-supported mitochondrial respiration of CPT2 deficient oxidative muscles shifted to closely match that of glycolytic muscles. Despite this shift in mitochondrial metabolism, CPT2 deletion did not result in contractile-based fiber type switching according to myosin heavy chain composition analysis. Conclusion The loss of mitochondrial long-chain fatty acid oxidation elicits an adaptive response involving conversion of oxidative muscle toward a metabolic profile that resembles a glycolytic muscle, but this is not accompanied by changes in myosin heavy chain isoforms. These data suggest that shifts in muscle catabolism are not sufficient to drive shifts in the contractile apparatus but are sufficient to drive adaptive changes in metabolic properties. Fuel oxidation in glycolytic compared to oxidative muscles are different and intrinsic to the mitochondria. Muscle CPT2 loss elicits fiber-type dependent mitochondrial biogenesis. Muscle CPT2 loss elicits an oxidative-to-glycolytic shift in mitochondrial and metabolic properties. Muscle CPT2 loss does not alter myosin heavy chain isoform composition. CPT2 deficient muscles demonstrate a metabolic-contractile apparatus mismatch.
Collapse
Affiliation(s)
- Andrea S Pereyra
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA.
| | - Chien-Te Lin
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | | | - Julia Laskin
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Espen E Spangenburg
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | - P Darrell Neufer
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | - Kelsey Fisher-Wellman
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA
| | - Jessica M Ellis
- Brody School of Medicine at East Carolina University, Department of Physiology and East Carolina Diabetes and Obesity Institute, Greenville, NC, 27834, USA.
| |
Collapse
|
8
|
Chalmers T, Maharaj S, Lees T, Lin CT, Newton P, Clifton-Bligh R, McLachlan CS, Gustin SM, Lal S. Impact of acute stress on cortical electrical activity and cardiac autonomic coupling. J Integr Neurosci 2021; 19:239-248. [PMID: 32706188 DOI: 10.31083/j.jin.2020.02.74] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/17/2020] [Indexed: 11/06/2022] Open
Abstract
Assessment of heart rate variability (reflective of the cardiac autonomic nervous system) has shown some predictive power for stress. Further, the predictive power of the distinct patterns of cortical brain activity and - cardiac autonomic interactions are yet to be explored in the context of acute stress, as assessed by an electrocardiogram and electroencephalogram. The present study identified distinct patterns of neural-cardiac autonomic coupling during both resting and acute stress states. In particular, during the stress task, frontal delta waves activity was positively associated with low-frequency heart rate variability and negatively associated with high-frequency heart rate variability. Low high-frequency power is associated with stress and anxiety and reduced vagal control. A positive association between resting high-frequency heart rate variability and frontocentral gamma activity was found, with a direct inverse relationship of low-frequency heart rate variability and gamma wave coupling at rest. During the stress task, low-frequency heart rate variability was positively associated with frontal delta activity. That is, the parasympathetic nervous system is reduced during a stress task, whereas frontal delta wave activity is increased. Our findings suggest an association between cardiac parasympathetic nervous system activity and frontocentral gamma and delta activity at rest and during acute stress. This suggests that parasympathetic activity is decreased during acute stress, and this is coupled with neuronal cortical prefrontal activity. The distinct patterns of neural-cardiac coupling identified in this study provide a unique insight into the dynamic associations between brain and heart function during both resting and acute stress states.
Collapse
Affiliation(s)
- Taryn Chalmers
- Neuroscience Research Unit, School of Technology Sydney, PO Box 123, Australia
| | - Shamona Maharaj
- Neuroscience Research Unit, School of Technology Sydney, PO Box 123, Australia
| | - Ty Lees
- Edna Bennett Pierce Prevention Research Center, Pennsylvania State University, PA, 16802, USA
| | - C T Lin
- Computational Intelligence and Brain Computer Interface Centre (CIBCI), Faculty of Engineering and Information Technology (FEIT), University of Technology Sydney, PO Box 123, Australia
| | - Phillip Newton
- School of Nursing and Midwifery, Western Sydney University, Locked Bag 1797, Penrith NSW 2751, Australia
| | - Roderick Clifton-Bligh
- Medicine, Kolling Institute of Medical Research, Northern Clinical School, University of Sydney, NSW 2065, Australia
| | - Craig S McLachlan
- Centre for Healthy Futures, Health Faculty, Pyrmont Campus, Sydney, Torrens University Australia, NSW 2009, Australia
| | - Sylvia M Gustin
- School of Psychology, University of New South Wales, Sydney, NSW 2052, Australia.,Neuroscience Research Australia, Sydney, NSW 2031, Australia
| | - Sara Lal
- Neuroscience Research Unit, School of Technology Sydney, PO Box 123, Australia
| |
Collapse
|
9
|
Smith CD, Lin CT, McMillin SL, Weyrauch LA, Schmidt CA, Smith CA, Kurland IJ, Witczak CA, Neufer PD. Genetically increasing flux through β-oxidation in skeletal muscle increases mitochondrial reductive stress and glucose intolerance. Am J Physiol Endocrinol Metab 2021; 320:E938-E950. [PMID: 33813880 PMCID: PMC8238127 DOI: 10.1152/ajpendo.00010.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Elevated mitochondrial hydrogen peroxide (H2O2) emission and an oxidative shift in cytosolic redox environment have been linked to high-fat-diet-induced insulin resistance in skeletal muscle. To test specifically whether increased flux through mitochondrial fatty acid oxidation, in the absence of elevated energy demand, directly alters mitochondrial function and redox state in muscle, two genetic models characterized by increased muscle β-oxidation flux were studied. In mice overexpressing peroxisome proliferator-activated receptor-α in muscle (MCK-PPARα), lipid-supported mitochondrial respiration, membrane potential (ΔΨm), and H2O2 production rate (JH2O2) were increased, which coincided with a more oxidized cytosolic redox environment, reduced muscle glucose uptake, and whole body glucose intolerance despite an increased rate of energy expenditure. Similar results were observed in lipin-1-deficient, fatty-liver dystrophic mice, another model characterized by increased β-oxidation flux and glucose intolerance. Crossing MCAT (mitochondria-targeted catalase) with MCK-PPARα mice normalized JH2O2 production, redox environment, and glucose tolerance, but surprisingly, both basal and absolute insulin-stimulated rates of glucose uptake in muscle remained depressed. Also surprising, when placed on a high-fat diet, MCK-PPARα mice were characterized by much lower whole body, fat, and lean mass as well as improved glucose tolerance relative to wild-type mice, providing additional evidence that overexpression of PPARα in muscle imposes more extensive metabolic stress than experienced by wild-type mice on a high-fat diet. Overall, the findings suggest that driving an increase in skeletal muscle fatty acid oxidation in the absence of metabolic demand imposes mitochondrial reductive stress and elicits multiple counterbalance metabolic responses in an attempt to restore bioenergetic homeostasis.NEW & NOTEWORTHY Prior work has suggested that mitochondrial dysfunction is an underlying cause of insulin resistance in muscle because it limits fatty acid oxidation and therefore leads to the accumulation of cytotoxic lipid intermediates. The implication has been that therapeutic strategies to accelerate β-oxidation will be protective. The current study provides evidence that genetically increasing flux through β-oxidation in muscle imposes reductive stress that is not beneficial but rather detrimental to metabolic regulation.
Collapse
Affiliation(s)
- Cody D Smith
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Shawna L McMillin
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Luke A Weyrauch
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Cameron A Schmidt
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Cheryl A Smith
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Irwin J Kurland
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Carol A Witczak
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Kinesiology, East Carolina University, Greenville, North Carolina
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina
- Department of Kinesiology, East Carolina University, Greenville, North Carolina
| |
Collapse
|
10
|
Schmidt CA, McLaughlin KL, Boykov IN, Mojalagbe R, Ranganathan A, Buddo KA, Lin CT, Fisher-Wellman KH, Neufer PD. Aglycemic growth enhances carbohydrate metabolism and induces sensitivity to menadione in cultured tumor-derived cells. Cancer Metab 2021; 9:3. [PMID: 33468237 PMCID: PMC7816515 DOI: 10.1186/s40170-021-00241-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 01/06/2021] [Indexed: 12/19/2022] Open
Abstract
Background Hepatocellular carcinoma (HCC) is the most prevalent form of liver malignancy and carries poor prognoses due to late presentation of symptoms. Treatment of late-stage HCC relies heavily on chemotherapeutics, many of which target cellular energy metabolism. A key platform for testing candidate chemotherapeutic compounds is the intrahepatic orthotopic xenograft (IOX) model in rodents. Translational efficacy from the IOX model to clinical use is limited (in part) by variation in the metabolic phenotypes of the tumor-derived cells that can be induced by selective adaptation to subculture conditions. Methods In this study, a detailed multilevel systems approach combining microscopy, respirometry, potentiometry, and extracellular flux analysis (EFA) was utilized to examine metabolic adaptations that occur under aglycemic growth media conditions in HCC-derived (HEPG2) cells. We hypothesized that aglycemic growth would result in adaptive “aerobic poise” characterized by enhanced capacity for oxidative phosphorylation over a range of physiological energetic demand states. Results Aglycemic growth did not invoke adaptive changes in mitochondrial content, network complexity, or intrinsic functional capacity/efficiency. In intact cells, aglycemic growth markedly enhanced fermentative glycolytic substrate-level phosphorylation during glucose refeeding and enhanced responsiveness of both fermentation and oxidative phosphorylation to stimulated energy demand. Additionally, aglycemic growth induced sensitivity of HEPG2 cells to the provitamin menadione at a 25-fold lower dose compared to control cells. Conclusions These findings indicate that growth media conditions have substantial effects on the energy metabolism of subcultured tumor-derived cells, which may have significant implications for chemotherapeutic sensitivity during incorporation in IOX testing panels. Additionally, the metabolic phenotyping approach used in this study provides a practical workflow that can be incorporated with IOX screening practices to aid in deciphering the metabolic underpinnings of chemotherapeutic drug sensitivity. Supplementary Information The online version contains supplementary material available at 10.1186/s40170-021-00241-0.
Collapse
Affiliation(s)
- Cameron A Schmidt
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA.,Dept. of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Kelsey L McLaughlin
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA.,Dept. of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Ilya N Boykov
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA.,Dept. of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Rafiq Mojalagbe
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA
| | | | - Katherine A Buddo
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA.,Dept. of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA.,Dept. of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Kelsey H Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA. .,Dept. of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA.
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Greenville, NC, USA. .,Dept. of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA.
| |
Collapse
|
11
|
Smith CD, Schmidt CA, Lin CT, Fisher-Wellman KH, Neufer PD. Flux through mitochondrial redox circuits linked to nicotinamide nucleotide transhydrogenase generates counterbalance changes in energy expenditure. J Biol Chem 2020; 295:16207-16216. [PMID: 32747443 DOI: 10.1074/jbc.ra120.013899] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 07/15/2020] [Indexed: 01/21/2023] Open
Abstract
Compensatory changes in energy expenditure occur in response to positive and negative energy balance, but the underlying mechanism remains unclear. Under low energy demand, the mitochondrial electron transport system is particularly sensitive to added energy supply (i.e. reductive stress), which exponentially increases the rate of H2O2 (JH2O2) production. H2O2 is reduced to H2O by electrons supplied by NADPH. NADP+ is reduced back to NADPH by activation of mitochondrial membrane potential-dependent nicotinamide nucleotide transhydrogenase (NNT). The coupling of reductive stress-induced JH2O2 production to NNT-linked redox buffering circuits provides a potential means of integrating energy balance with energy expenditure. To test this hypothesis, energy supply was manipulated by varying flux rate through β-oxidation in muscle mitochondria minus/plus pharmacological or genetic inhibition of redox buffering circuits. Here we show during both non-ADP- and low-ADP-stimulated respiration that accelerating flux through β-oxidation generates a corresponding increase in mitochondrial JH2O2 production, that the majority (∼70-80%) of H2O2 produced is reduced to H2O by electrons drawn from redox buffering circuits supplied by NADPH, and that the rate of electron flux through redox buffering circuits is directly linked to changes in oxygen consumption mediated by NNT. These findings provide evidence that redox reactions within β-oxidation and the electron transport system serve as a barometer of substrate flux relative to demand, continuously adjusting JH2O2 production and, in turn, the rate at which energy is expended via NNT-mediated proton conductance. This variable flux through redox circuits provides a potential compensatory mechanism for fine-tuning energy expenditure to energy balance in real time.
Collapse
Affiliation(s)
- Cody D Smith
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Cameron A Schmidt
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Kelsey H Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA; Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.
| |
Collapse
|
12
|
Iñigo MR, Amorese AJ, Tarpey MD, Balestrieri NP, Jones KG, Patteson DJ, Jackson KC, Torres MJ, Lin CT, Smith CD, Heden TD, McMillin SL, Weyrauch LA, Stanley EC, Schmidt CA, Kilburg-Basnyat BB, Reece SW, Psaltis CE, Leinwand LA, Funai K, McClung JM, Gowdy KM, Witczak CA, Lowe DA, Neufer PD, Spangenburg EE. Estrogen receptor-α in female skeletal muscle is not required for regulation of muscle insulin sensitivity and mitochondrial regulation. Mol Metab 2020; 34:1-15. [PMID: 32180550 PMCID: PMC6994285 DOI: 10.1016/j.molmet.2019.12.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVE Estrogen receptor-α (ERα) is a nuclear receptor family member thought to substantially contribute to the metabolic regulation of skeletal muscle. However, previous mouse models utilized to assess the necessity of ERα signaling in skeletal muscle were confounded by altered developmental programming and/or influenced by secondary effects, making it difficult to assign a causal role for ERα. The objective of this study was to determine the role of skeletal muscle ERα in regulating metabolism in the absence of confounding factors of development. METHODS A novel mouse model was developed allowing for induced deletion of ERα in adult female skeletal muscle (ERαKOism). ERαshRNA was also used to knockdown ERα (ERαKD) in human myotubes cultured from primary human skeletal muscle cells isolated from muscle biopsies from healthy and obese insulin-resistant women. RESULTS Twelve weeks of HFD exposure had no differential effects on body composition, VO2, VCO2, RER, energy expenditure, and activity counts across genotypes. Although ERαKOism mice exhibited greater glucose intolerance than wild-type (WT) mice after chronic HFD, ex vivo skeletal muscle glucose uptake was not impaired in the ERαKOism mice. Expression of pro-inflammatory genes was altered in the skeletal muscle of the ERαKOism, but the concentrations of these inflammatory markers in the systemic circulation were either lower or remained similar to the WT mice. Finally, skeletal muscle mitochondrial respiratory capacity, oxidative phosphorylation efficiency, and H2O2 emission potential was not affected in the ERαKOism mice. ERαKD in human skeletal muscle cells neither altered differentiation capacity nor caused severe deficits in mitochondrial respiratory capacity. CONCLUSIONS Collectively, these results suggest that ERα function is superfluous in protecting against HFD-induced skeletal muscle metabolic derangements after postnatal development is complete.
Collapse
Affiliation(s)
- Melissa R Iñigo
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA
| | - Adam J Amorese
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA
| | - Michael D Tarpey
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA
| | - Nicholas P Balestrieri
- East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA
| | - Keith G Jones
- East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA
| | - Daniel J Patteson
- East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA
| | - Kathryn C Jackson
- University of Maryland, School of Public Health, Department of Kinesiology, College Park, MD, USA
| | - Maria J Torres
- East Carolina University, Department of Kinesiology, Greenville, NC, USA
| | - Chien-Te Lin
- East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA
| | - Cody D Smith
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA
| | - Timothy D Heden
- East Carolina University, Department of Kinesiology, Greenville, NC, USA
| | - Shawna L McMillin
- East Carolina University, Department of Kinesiology, Greenville, NC, USA
| | - Luke A Weyrauch
- East Carolina University, Department of Kinesiology, Greenville, NC, USA
| | - Erin C Stanley
- East Carolina University, Department of Kinesiology, Greenville, NC, USA
| | - Cameron A Schmidt
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA
| | - Brita B Kilburg-Basnyat
- East Carolina University Brody School of Medicine, Department of Pharmacology and Toxicology, Greenville, NC, USA
| | - Sky W Reece
- East Carolina University Brody School of Medicine, Department of Pharmacology and Toxicology, Greenville, NC, USA
| | - Christine E Psaltis
- East Carolina University Brody School of Medicine, Department of Pharmacology and Toxicology, Greenville, NC, USA
| | - Leslie A Leinwand
- University of Colorado, Department of Molecular, Cellular, and Developmental Biology and BioFrontiers Institute, Boulder, CO, USA
| | - Katsuhiko Funai
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA; East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA; East Carolina University, Department of Kinesiology, Greenville, NC, USA
| | - Joseph M McClung
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA; East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA
| | - Kymberly M Gowdy
- East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA; East Carolina University Brody School of Medicine, Department of Pharmacology and Toxicology, Greenville, NC, USA
| | - Carol A Witczak
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA; East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA; East Carolina University, Department of Kinesiology, Greenville, NC, USA; East Carolina University, Department of Biochemistry and Molecular Biology, Greenville, NC, USA
| | - Dawn A Lowe
- University of Minnesota, Department of Rehabilitation Medicine, Division of Rehabilitation Science and Division of Physical Therapy, Minneapolis, MN, USA
| | - P Darrell Neufer
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA; East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA; East Carolina University, Department of Kinesiology, Greenville, NC, USA
| | - Espen E Spangenburg
- East Carolina University Brody School of Medicine, Department of Physiology, Greenville, NC, USA; East Carolina University, East Carolina Diabetes and Obesity Institute, Greenville, NC, USA; East Carolina University, Department of Kinesiology, Greenville, NC, USA.
| |
Collapse
|
13
|
Johnson JM, Verkerke ARP, Maschek JA, Ferrara PJ, Lin CT, Kew KA, Neufer PD, Lodhi IJ, Cox JE, Funai K. Alternative splicing of UCP1 by non-cell-autonomous action of PEMT. Mol Metab 2020; 31:55-66. [PMID: 31918922 PMCID: PMC6889607 DOI: 10.1016/j.molmet.2019.10.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/14/2019] [Accepted: 10/30/2019] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE Phosphatidylethanolamine methyltransferase (PEMT) generates phosphatidylcholine (PC), the most abundant phospholipid in the mitochondria and an important acyl chain donor for cardiolipin (CL) biosynthesis. Mice lacking PEMT (PEMTKO) are cold-intolerant when fed a high-fat diet (HFD) due to unclear mechanisms. The purpose of this study was to determine whether PEMT-derived phospholipids are important for the function of uncoupling protein 1 (UCP1) and thus for maintenance of core temperature. METHODS To test whether PEMT-derived phospholipids are important for UCP1 function, we examined cold-tolerance and brown adipose (BAT) mitochondria from PEMTKO mice with or without HFD feeding. We complemented these studies with experiments on mice lacking functional CL due to tafazzin knockdown (TAZKD). We generated several conditional mouse models to study the tissue-specific roles of PEMT, including mice with BAT-specific knockout of PEMT (PEMT-BKO). RESULTS Chow- and HFD-fed PEMTKO mice completely lacked UCP1 protein in BAT, despite a lack of difference in mRNA levels, and the mice were accordingly cold-intolerant. While HFD-fed PEMTKO mice exhibited reduced mitochondrial CL content, this was not observed in chow-fed PEMTKO mice or TAZKD mice, indicating that the lack of UCP1 was not attributable to CL deficiency. Surprisingly, the PEMT-BKO mice exhibited normal UCP1 protein levels. Knockout of PEMT in the adipose tissue (PEMT-AKO), liver (PEMT-LKO), or skeletal muscle (PEMT-MKO) also did not affect UCP1 protein levels, suggesting that lack of PEMT in other non-UCP1-expressing cells communicates to BAT to suppress UCP1. Instead, we identified an untranslated UCP1 splice variant that was triggered during the perinatal period in the PEMTKO mice. CONCLUSIONS PEMT is required for UCP1 splicing that yields functional protein. This effect is derived by PEMT in nonadipocytes that communicates to BAT during embryonic development. Future research will focus on identifying the non-cell-autonomous PEMT-dependent mechanism of UCP1 splicing.
Collapse
Affiliation(s)
- Jordan M Johnson
- Diabetes & Metabolism Research Center, University of Utah, 15 N. 2030 E, Salt Lake City, UT, 84112, USA; Department of Nutrition & Integrative Physiology, University of Utah, 250 S. 1850 E., RM 214, Salt Lake City, UT, 84112, USA; Department of Physical Therapy & Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT, 84108, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, 115 Heart Drive, 4101 ECHI, Greenville, NC, 27834, USA
| | - Anthony R P Verkerke
- Diabetes & Metabolism Research Center, University of Utah, 15 N. 2030 E, Salt Lake City, UT, 84112, USA; Department of Nutrition & Integrative Physiology, University of Utah, 250 S. 1850 E., RM 214, Salt Lake City, UT, 84112, USA; Department of Physical Therapy & Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT, 84108, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, 115 Heart Drive, 4101 ECHI, Greenville, NC, 27834, USA
| | - J Alan Maschek
- Diabetes & Metabolism Research Center, University of Utah, 15 N. 2030 E, Salt Lake City, UT, 84112, USA; Metabolomics Core Research Facility, University of Utah, 15 N. Medical Dr. East RM A306, Salt Lake City, UT, 84112, USA; Department of Biochemistry, University of Utah, 15 N. Medical Dr. East RM 4100, Salt Lake City, UT, 84112, USA
| | - Patrick J Ferrara
- Diabetes & Metabolism Research Center, University of Utah, 15 N. 2030 E, Salt Lake City, UT, 84112, USA; Department of Nutrition & Integrative Physiology, University of Utah, 250 S. 1850 E., RM 214, Salt Lake City, UT, 84112, USA; Department of Physical Therapy & Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT, 84108, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, 115 Heart Drive, 4101 ECHI, Greenville, NC, 27834, USA
| | - Chien-Te Lin
- East Carolina Diabetes & Obesity Institute, East Carolina University, 115 Heart Drive, 4101 ECHI, Greenville, NC, 27834, USA
| | - Kimberly A Kew
- East Carolina Diabetes & Obesity Institute, East Carolina University, 115 Heart Drive, 4101 ECHI, Greenville, NC, 27834, USA; Department of Chemistry, East Carolina University, Greenville, NC, 27858, USA
| | - P Darrell Neufer
- East Carolina Diabetes & Obesity Institute, East Carolina University, 115 Heart Drive, 4101 ECHI, Greenville, NC, 27834, USA
| | - Irfan J Lodhi
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO, 63110, USA
| | - James E Cox
- Diabetes & Metabolism Research Center, University of Utah, 15 N. 2030 E, Salt Lake City, UT, 84112, USA; Metabolomics Core Research Facility, University of Utah, 15 N. Medical Dr. East RM A306, Salt Lake City, UT, 84112, USA; Department of Biochemistry, University of Utah, 15 N. Medical Dr. East RM 4100, Salt Lake City, UT, 84112, USA
| | - Katsuhiko Funai
- Diabetes & Metabolism Research Center, University of Utah, 15 N. 2030 E, Salt Lake City, UT, 84112, USA; Department of Nutrition & Integrative Physiology, University of Utah, 250 S. 1850 E., RM 214, Salt Lake City, UT, 84112, USA; Department of Physical Therapy & Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT, 84108, USA; East Carolina Diabetes & Obesity Institute, East Carolina University, 115 Heart Drive, 4101 ECHI, Greenville, NC, 27834, USA; Molecular Medicine Program, University of Utah, 15 N. 2030 E. RM 4145, Salt Lake City, UT, 84112, USA.
| |
Collapse
|
14
|
Fisher-Wellman KH, Davidson MT, Narowski TM, Lin CT, Koves TR, Muoio DM. Mitochondrial Diagnostics: A Multiplexed Assay Platform for Comprehensive Assessment of Mitochondrial Energy Fluxes. Cell Rep 2019; 24:3593-3606.e10. [PMID: 30257218 DOI: 10.1016/j.celrep.2018.08.091] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 06/23/2018] [Accepted: 08/29/2018] [Indexed: 12/17/2022] Open
Abstract
Chronic metabolic diseases have been linked to molecular signatures of mitochondrial dysfunction. Nonetheless, molecular remodeling of the transcriptome, proteome, and/or metabolome does not necessarily translate to functional consequences that confer physiologic phenotypes. The work here aims to bridge the gap between molecular and functional phenomics by developing and validating a multiplexed assay platform for comprehensive assessment of mitochondrial energy transduction. The diagnostic power of the platform stems from a modified version of the creatine kinase energetic clamp technique, performed in parallel with multiplexed analyses of dehydrogenase activities and ATP synthesis rates. Together, these assays provide diagnostic coverage of the mitochondrial network at a level approaching that gained by molecular "-omics" technologies. Application of the platform to a comparison of skeletal muscle versus heart mitochondria reveals mechanistic insights into tissue-specific distinctions in energy transfer efficiency. This platform opens exciting opportunities to unravel the connection between mitochondrial bioenergetics and human disease.
Collapse
Affiliation(s)
- Kelsey H Fisher-Wellman
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
| | - Michael T Davidson
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Tara M Narowski
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Timothy R Koves
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Deborah M Muoio
- Departments of Medicine and Pharmacology and Cancer Biology, Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA.
| |
Collapse
|
15
|
Verkerke ARP, Ferrara PJ, Lin CT, Johnson JM, Ryan TE, Maschek JA, Eshima H, Paran CW, Laing BT, Siripoksup P, Tippetts TS, Wentzler EJ, Huang H, Spangenburg EE, Brault JJ, Villanueva CJ, Summers SA, Holland WL, Cox JE, Vance DE, Neufer PD, Funai K. Phospholipid methylation regulates muscle metabolic rate through Ca 2+ transport efficiency. Nat Metab 2019; 1:876-885. [PMID: 32405618 PMCID: PMC7218817 DOI: 10.1038/s42255-019-0111-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The biophysical environment of membrane phospholipids affects structure, function, and stability of membrane-bound proteins.1,2 Obesity can disrupt membrane lipids, and in particular, alter the activity of sarco/endoplasmic reticulum (ER/SR) Ca2+-ATPase (SERCA) to affect cellular metabolism.3-5 Recent evidence suggests that transport efficiency (Ca2+ uptake / ATP hydrolysis) of skeletal muscle SERCA can be uncoupled to increase energy expenditure and protect mice from diet-induced obesity.6,7 In isolated SR vesicles, membrane phospholipid composition is known to modulate SERCA efficiency.8-11 Here we show that skeletal muscle SR phospholipids can be altered to decrease SERCA efficiency and increase whole-body metabolic rate. The absence of skeletal muscle phosphatidylethanolamine (PE) methyltransferase (PEMT) promotes an increase in skeletal muscle and whole-body metabolic rate to protect mice from diet-induced obesity. The elevation in metabolic rate is caused by a decrease in SERCA Ca2+-transport efficiency, whereas mitochondrial uncoupling is unaffected. Our findings support the hypothesis that skeletal muscle energy efficiency can be reduced to promote protection from obesity.
Collapse
Affiliation(s)
- Anthony R P Verkerke
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Patrick J Ferrara
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Jordan M Johnson
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Terence E Ryan
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA
| | - J Alan Maschek
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
| | - Hiroaki Eshima
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
| | - Christopher W Paran
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Brenton T Laing
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Piyarat Siripoksup
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA
| | - Trevor S Tippetts
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Edward J Wentzler
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Hu Huang
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Espen E Spangenburg
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Jeffrey J Brault
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Claudio J Villanueva
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Scott A Summers
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - William L Holland
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - James E Cox
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Dennis E Vance
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Katsuhiko Funai
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA.
- Department of Nutrition & Integrative Physiology, University of Utah, Salt Lake City, UT, USA.
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA.
- Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA.
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.
| |
Collapse
|
16
|
Heden TD, Johnson JM, Ferrara PJ, Eshima H, Verkerke ARP, Wentzler EJ, Siripoksup P, Narowski TM, Coleman CB, Lin CT, Ryan TE, Reidy PT, de Castro Brás LE, Karner CM, Burant CF, Maschek JA, Cox JE, Mashek DG, Kardon G, Boudina S, Zeczycki TN, Rutter J, Shaikh SR, Vance JE, Drummond MJ, Neufer PD, Funai K. Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity. Sci Adv 2019; 5:eaax8352. [PMID: 31535029 PMCID: PMC6739096 DOI: 10.1126/sciadv.aax8352] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/15/2019] [Indexed: 05/08/2023]
Abstract
Exercise capacity is a strong predictor of all-cause mortality. Skeletal muscle mitochondrial respiratory capacity, its biggest contributor, adapts robustly to changes in energy demands induced by contractile activity. While transcriptional regulation of mitochondrial enzymes has been extensively studied, there is limited information on how mitochondrial membrane lipids are regulated. Here, we show that exercise training or muscle disuse alters mitochondrial membrane phospholipids including phosphatidylethanolamine (PE). Addition of PE promoted, whereas removal of PE diminished, mitochondrial respiratory capacity. Unexpectedly, skeletal muscle-specific inhibition of mitochondria-autonomous synthesis of PE caused respiratory failure because of metabolic insults in the diaphragm muscle. While mitochondrial PE deficiency coincided with increased oxidative stress, neutralization of the latter did not rescue lethality. These findings highlight the previously underappreciated role of mitochondrial membrane phospholipids in dynamically controlling skeletal muscle energetics and function.
Collapse
Affiliation(s)
- Timothy D. Heden
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Jordan M. Johnson
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
| | - Patrick J. Ferrara
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
| | - Hiroaki Eshima
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
| | - Anthony R. P. Verkerke
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
| | - Edward J. Wentzler
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Piyarat Siripoksup
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
| | - Tara M. Narowski
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Chanel B. Coleman
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Physiology, East Carolina University, Greenville, NC, USA
| | - Terence E. Ryan
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Physiology, East Carolina University, Greenville, NC, USA
- Department of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL, USA
| | - Paul T. Reidy
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
| | | | - Courtney M. Karner
- Department of Orthopedic Surgery & Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA
| | - Charles F. Burant
- Michigan Regional Comprehensive Metabolomics Resource Core, University of Michigan, Ann Arbor, MI, USA
| | - J. Alan Maschek
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
| | - James E. Cox
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Research Facility, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Douglas G. Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Gabrielle Kardon
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Sihem Boudina
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - Tonya N. Zeczycki
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Biochemistry and Molecular Biology, East Carolina University, Greenville, NC, USA
| | - Jared Rutter
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Saame Raza Shaikh
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Biochemistry and Molecular Biology, East Carolina University, Greenville, NC, USA
- Department of Nutrition, University of North Carolina, Chapel Hill, NC, USA
| | - Jean E. Vance
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Micah J. Drummond
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - P. Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Department of Physiology, East Carolina University, Greenville, NC, USA
| | - Katsuhiko Funai
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
- Department of Physiology, East Carolina University, Greenville, NC, USA
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
- Corresponding author.
| |
Collapse
|
17
|
Chen YM, Hung WT, Liao YW, Hsu CY, Hsieh TY, Chen HH, Hsieh CW, Lin CT, Lai KL, Tang KT, Tseng CW, Huang WN, Chen YH. Combination immunosuppressant therapy and lupus nephritis outcome: a hospital-based study. Lupus 2019; 28:658-666. [PMID: 30971165 DOI: 10.1177/0961203319842663] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Lupus nephritis (LN) is the leading cause of mortality in lupus patients. This study aimed to investigate the treatment outcome and renal histological risk factors of LN in a tertiary referral center. Between 2006 and 2017, a retrospective observational study enrolled 148 biopsy-proven LN patients. After propensity score matching, 75 cases were included for further analysis. The classification and scoring of LN were assessed according to the International Society of Nephrology/Renal Pathology Society. Treatment response was evaluated by daily urine protein and urinalysis at two years after commencing induction treatment and the development of end-stage renal disease (ESRD). In total, 50.7% patients achieved complete remission (CR) or partial remission (PR), while 49.3% patients were categorized as nonresponders. Therapeutic responses in terms of CR/PR rates were associated with Systemic Lupus Erythematosus Disease Activity Index scores (odds ratio (OR): 1.34, 95% confidence interval (CI): 1.12-1.60, p = 0.001). Moreover, higher baseline creatinine levels (hazard ratio (HR): 2.10, 95% CI: 1.29-3.40, p = 0.003), higher renal activity index (HR: 1.30, 95% CI: 1.07-1.58, p = 0.008) and chronicity index (HR: 1.40, 95% CI: 1.06-1.85, p = 0.017) predicted ESRD. Among pathological scores, cellular crescents (HR: 4.42, 95% CI: 1.01-19.38, p = 0.049) and fibrous crescents (HR: 5.93, 95% CI: 1.41-24.92, p = 0.015) were independent risk factors for ESRD. In conclusion, higher lupus activity was a good prognostic marker for renal remission. Renal histology was predictive of ESRD. Large-scale prospective studies are required to verify the efficacy of mycophenolate in combination with azathioprine or cyclosporine in LN patients.
Collapse
Affiliation(s)
- Y M Chen
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung.,2 Department of Medical Research, Taichung Veterans General Hospital, Taichung.,3 Faculty of Medicine, National Yang-Ming University, Taipei.,4 Institute of Biomedical Science and Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung
| | - W T Hung
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung.,5 Department of Medical Education, Taichung Veterans General Hospital, Taichung.,6 Institute of Clinical Medicine, National Yang-Ming University, Taipei
| | - Y W Liao
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung
| | - C Y Hsu
- 2 Department of Medical Research, Taichung Veterans General Hospital, Taichung
| | - T Y Hsieh
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung.,5 Department of Medical Education, Taichung Veterans General Hospital, Taichung
| | - H H Chen
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung.,2 Department of Medical Research, Taichung Veterans General Hospital, Taichung.,3 Faculty of Medicine, National Yang-Ming University, Taipei.,4 Institute of Biomedical Science and Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung
| | - C W Hsieh
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung.,5 Department of Medical Education, Taichung Veterans General Hospital, Taichung
| | - C T Lin
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung
| | - K L Lai
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung
| | - K T Tang
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung
| | - C W Tseng
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung
| | - W N Huang
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung.,3 Faculty of Medicine, National Yang-Ming University, Taipei
| | - Y H Chen
- 1 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung.,3 Faculty of Medicine, National Yang-Ming University, Taipei
| |
Collapse
|
18
|
Torres MJ, Ryan TE, Lin CT, Zeczycki TN, Neufer PD. Impact of 17β-estradiol on complex I kinetics and H 2O 2 production in liver and skeletal muscle mitochondria. J Biol Chem 2018; 293:16889-16898. [PMID: 30217819 DOI: 10.1074/jbc.ra118.005148] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/11/2018] [Indexed: 12/14/2022] Open
Abstract
Naturally or surgically induced postmenopausal women are widely prescribed estrogen therapies to alleviate symptoms associated with estrogen loss and to lower the subsequent risk of developing metabolic diseases, including diabetes and nonalcoholic fatty liver disease. However, the molecular mechanisms by which estrogens modulate metabolism across tissues remain ill-defined. We have previously reported that 17β-estradiol (E2) exerts antidiabetogenic effects in ovariectomized (OVX) mice by protecting mitochondrial and cellular redox function in skeletal muscle. The liver is another key tissue for glucose homeostasis and a target of E2 therapy. Thus, in the present study we determined the effects of acute loss of ovarian E2 and E2 administration on liver mitochondria. In contrast to skeletal muscle mitochondria, E2 depletion via OVX did not alter liver mitochondrial respiratory function or complex I (CI) specific activities (NADH oxidation, quinone reduction, and H2O2 production). Surprisingly, in vivo E2 replacement therapy and in vitro E2 exposure induced tissue-specific effects on both CI activity and on the rate and topology of CI H2O2 production. Overall, E2 therapy protected and restored the OVX-induced reduction in CI activity in skeletal muscle, whereas in liver mitochondria E2 increased CI H2O2 production and decreased ADP-stimulated respiratory capacity. These results offer novel insights into the tissue-specific effects of E2 on mitochondrial function.
Collapse
Affiliation(s)
- Maria J Torres
- From the East Carolina Diabetes and Obesity Institute.,the Department of Kinesiology, and
| | - Terence E Ryan
- From the East Carolina Diabetes and Obesity Institute.,the Departments of Physiology, and
| | - Chien-Te Lin
- From the East Carolina Diabetes and Obesity Institute.,the Departments of Physiology, and
| | - Tonya N Zeczycki
- From the East Carolina Diabetes and Obesity Institute, .,Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina 27834
| | - P Darrell Neufer
- From the East Carolina Diabetes and Obesity Institute, .,the Department of Kinesiology, and.,the Departments of Physiology, and
| |
Collapse
|
19
|
Meneely S, Dinkins ML, Kassai M, Lyu S, Liu Y, Lin CT, Brewer K, Li Y, Clemens S. Differential Dopamine D1 and D3 Receptor Modulation and Expression in the Spinal Cord of Two Mouse Models of Restless Legs Syndrome. Front Behav Neurosci 2018; 12:199. [PMID: 30233336 PMCID: PMC6131574 DOI: 10.3389/fnbeh.2018.00199] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 08/13/2018] [Indexed: 12/22/2022] Open
Abstract
Restless Legs Syndrome (RLS) is often and successfully treated with dopamine receptor agonists that target the inhibitory D3 receptor subtype, however there is no clinical evidence of a D3 receptor dysfunction in RLS patients. In contrast, genome-wide association studies in RLS patients have established that a mutation of the MEIS1 gene is associated with an increased risk in developing RLS, but the effect of MEIS1 dysfunction on sensorimotor function remain unknown. Mouse models for a dysfunctional D3 receptor (D3KO) and Meis1 (Meis1KO) were developed independently, and each animal expresses some features associated with RLS in the clinic, but they have not been compared in their responsiveness to treatment options used in the clinic. We here confirm that D3KO and Meis1KO animals show increased locomotor activities, but that only D3KO show an increased sensory excitability to thermal stimuli. Next we compared the effects of dopaminergics and opioids in both animal models, and we assessed D1 and D3 dopamine receptor expression in the spinal cord, the gateway for sensorimotor processing. We found that Meis1KO share most of the tested behavioral properties with their wild type (WT) controls, including the modulation of the thermal pain withdrawal reflex by morphine, L-DOPA and D3 receptor (D3R) agonists and antagonists. However, Meis1KO and D3KO were behaviorally more similar to each other than to WT when tested with D1 receptor (D1R) agonists and antagonists. Subsequent Western blot analyses of D1R and D3R protein expression in the spinal cord revealed a significant increase in D1R but not D3R expression in Meis1KO and D3KO over WT controls. As the D3R is mostly present in the dorsal spinal cord where it has been shown to modulate sensory pathways, while activation of the D1Rs can activate motoneurons in the ventral spinal cord, we speculate that D3KO and Meis1KO represent two complementary animal models for RLS, in which the mechanisms of sensory (D3R-mediated) and motor (D1R-mediated) dysfunctions can be differentially explored.
Collapse
Affiliation(s)
- Samantha Meneely
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Mai-Lynne Dinkins
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Miki Kassai
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Shangru Lyu
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Yuning Liu
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Chien-Te Lin
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
- East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Kori Brewer
- Department of Emergency Medicine, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Yuqing Li
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, United States
- Wuxi Medical School, Jiangnan University, Wuxi, China
| | - Stefan Clemens
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| |
Collapse
|
20
|
Li MT, Fang YF, Sun Z, Zhang JC, Lin CT. Evidence for weak collective pinning and δl pinning in topological superconductor Cu x Bi 2Se 3. J Phys Condens Matter 2018; 30:31LT01. [PMID: 29947615 DOI: 10.1088/1361-648x/aacf6a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We investigated the vortex pinning behavior in the single crystal topological superconductor Cu0.10Bi2Se3 with a pronounced anisotropic peak effect. A weak collective pinning regime is clarified from the power-law behavior in [Formula: see text] and the small critical current density ratio of [Formula: see text] ~ 10-5 ([Formula: see text] is the critical current density, [Formula: see text] is the depairing current density). The spatial variation of the charge-carrier mean free path induced pinning is evidenced and probably results from the well-defined atomic defects. Within the framework of collective pinning theory, we computed the values of the correlated length and volume at 1.8 K, which start declining prior to the onset field of the peak effect [Formula: see text], demonstrating the vortex lattices already suffered a preferential collapse ahead of the peak effect turns up. Thus, the peak effect can be understood by elastic moduli softening near the upper critical field [Formula: see text]. We suggest Cu x Bi2Se3 is a prototype topological material for investigating the vortex pinning dynamics associated with the peak effect phenomenon.
Collapse
Affiliation(s)
- M T Li
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany. Materials Genome Institute and Department of Physics, Shanghai University, Shanghai 200444, People's Republic of China
| | | | | | | | | |
Collapse
|
21
|
Hunt T, Odom M, Pak E, Tarpey M, Lin CT, Neufer D, Spangenburg E, Hannan J. MP09-11 MARKED INCREASE IN MITOCHONDRIAL RESPIRATION, HYDROGEN PEROXIDE EMITTING POTENTIAL AND ATP PRODUCTION IN THE UROTHELIUM VERSUS DETRUSOR SMOOTH MUSCLE. J Urol 2018. [DOI: 10.1016/j.juro.2018.02.337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
22
|
Li MT, Fang YF, Zhang JC, Yi HM, Zhou XJ, Lin CT. Magnetotransport study of topological superconductor Cu 0.10Bi 2Se 3 single crystal. J Phys Condens Matter 2018; 30:125702. [PMID: 29485100 DOI: 10.1088/1361-648x/aaaca1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report a magnetotransport study of vortex-pinning in Cu0.10Bi2Se3 single crystal. The sample is demonstrated to be in clean limit and absent of Pauli spin-limiting effect. Interestingly, the resistivity versus magnetic field shows an anomalously pronounced increase when approaching the superconducting-normal state boundary for both [Formula: see text] and [Formula: see text] configurations. We have investigated the flux-flowing behavior under various magnetic fields and temperatures, enabling us to establish its anisotropic vortex phase diagram. Our results suggest the Cu0.10Bi2Se3 can be served as one unique material for exploring exotic surface vortex states in topological superconductors.
Collapse
Affiliation(s)
- M T Li
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany. Materials Genome Institute and Department of Physics, Shanghai University, Shanghai 200444, People's Republic of China
| | | | | | | | | | | |
Collapse
|
23
|
Gavin TP, Ernst JM, Kwak HB, Caudill SE, Reed MA, Garner RT, Nie Y, Weiss JA, Pories WJ, Dar M, Lin CT, Hubal MJ, Neufer PD, Kuang S, Dohm GL. High Incomplete Skeletal Muscle Fatty Acid Oxidation Explains Low Muscle Insulin Sensitivity in Poorly Controlled T2D. J Clin Endocrinol Metab 2018; 103:882-889. [PMID: 29155999 DOI: 10.1210/jc.2017-01727] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/10/2017] [Indexed: 11/19/2022]
Abstract
CONTEXT Almost 50% of type 2 diabetic (T2D) patients are poorly controlled [glycated hemoglobin (HbA1c) ≥ 7%]; however, the mechanisms responsible for progressively worsening glycemic control are poorly understood. Lower skeletal muscle mitochondrial respiratory capacity is associated with low insulin sensitivity and the development of T2D. OBJECTIVE We investigated if skeletal muscle insulin sensitivity (SI) was different between well-controlled T2D (WCD) and poorly controlled T2D (PCD) and if the difference was associated with differences resulting from mitochondrial respiratory function. DESIGN Vastus lateralis muscle mitochondrial respiration, mitochondrial content, mitochondrial enzyme activity, and fatty acid oxidation (FAO) were measured. SI and the acute response to glucose (AIRg) were calculated by MINMOD analysis from glucose and insulin obtained during a modified, frequently sampled, intravenous glucose tolerance test. RESULTS SI and AIRg were lower in PCD than WCD. Muscle incomplete FAO was greater in PCD than WCD and greater incomplete FAO was associated with lower SI and higher HbA1c. Hydroxyacyl-coenzyme A dehydrogenase expression and activity were greater in PCD than WCD. There was no difference in maximal mitochondrial respiration or content between WCD and PCD. CONCLUSION The current results suggest that greater skeletal muscle incomplete FAO in poorly controlled T2D is due to elevated β oxidation and is associated with worsening muscle SI.
Collapse
Affiliation(s)
- Timothy P Gavin
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana
- Max E. Wastl Human Performance Laboratory; Purdue University, West Lafayette, Indiana
| | - Jacob M Ernst
- Department of Kinesiology, East Carolina University, Greenville, North Carolina
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina
| | - Hyo-Bum Kwak
- Department of Kinesiology, Inha University, Incheon, Korea
| | - Sarah E Caudill
- Department of Kinesiology, East Carolina University, Greenville, North Carolina
- Human Performance Laboratory, East Carolina University, Greenville, North Carolina
| | - Melissa A Reed
- Department of Kinesiology, West Chester University, West Chester, Pennsylvania
| | - Ron T Garner
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana
- Max E. Wastl Human Performance Laboratory; Purdue University, West Lafayette, Indiana
| | - Yaohui Nie
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana
- Max E. Wastl Human Performance Laboratory; Purdue University, West Lafayette, Indiana
- Department of Animal Sciences, Purdue University, West Lafayette, Indiana
| | - Jessica A Weiss
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana
- Max E. Wastl Human Performance Laboratory; Purdue University, West Lafayette, Indiana
| | - Walter J Pories
- Department of Surgery, East Carolina University, Greenville, North Carolina
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina
| | - Moahad Dar
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina
- Department of Medicine, East Carolina University, Greenville, North Carolina
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina
- Department of Physiology, East Carolina University, Greenville, North Carolina
| | - Monica J Hubal
- Departments of Integrative Systems Biology and Exercise and Nutrition Sciences, George Washington University, Washington, DC
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina
- Department of Physiology, East Carolina University, Greenville, North Carolina
| | - Shihuan Kuang
- Department of Animal Sciences, Purdue University, West Lafayette, Indiana
| | - G Lynis Dohm
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina
- Department of Physiology, East Carolina University, Greenville, North Carolina
| |
Collapse
|
24
|
Zhu GY, Lin CT, Chen JM, Lei DM, Zhu GX. The study of size and stability of n-butylcyanoacrylate nanocapsule suspensions encapsulating green grass fragrance. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1757-899x/292/1/012094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
25
|
Kawasaki S, Li Z, Kitahashi M, Lin CT, Kuhns PL, Reyes AP, Zheng GQ. Charge-density-wave order takes over antiferromagnetism in Bi 2Sr 2-x La x CuO 6 superconductors. Nat Commun 2017; 8:1267. [PMID: 29097672 PMCID: PMC5668353 DOI: 10.1038/s41467-017-01465-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 09/19/2017] [Indexed: 11/17/2022] Open
Abstract
Superconductivity appears in the cuprates when a spin order is destroyed, while the role of charge is less known. Recently, charge density wave (CDW) was found below the superconducting dome in YBa2Cu3Oy when a high magnetic field is applied perpendicular to the CuO2 plane, which was suggested to arise from incipient CDW in the vortex cores that becomes overlapped. Here by 63Cu-nuclear magnetic resonance, we report the discovery of CDW induced by an in-plane field, setting in above the dome in single-layered Bi2Sr2−xLaxCuO6. The onset temperature TCDW takes over the antiferromagnetic order temperature TN beyond a critical doping level at which superconductivity starts to emerge, and scales with the pseudogap temperature T*. These results provide important insights into the relationship between spin order, CDW and the pseudogap, and their connections to high-temperature superconductivity. Whilst superconductivity usually appears when magnetic order is suppressed, the role of charge is less known. Here, Kawasaki et al. report a charge density wave (CDW) above the superconducting transition induced by an in-plane magnetic field in Bi2Sr2-xLaxCuO6, with the CDW onset temperature scaling with the pseudogap temperature.
Collapse
Affiliation(s)
- S Kawasaki
- Department of Physics, Okayama University, Okayama, 700-8530, Japan
| | - Z Li
- Institute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter Physics, 100190, Beijing, China
| | - M Kitahashi
- Department of Physics, Okayama University, Okayama, 700-8530, Japan
| | - C T Lin
- Max-Planck-Institut fur Festkorperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
| | - P L Kuhns
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - A P Reyes
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Guo-Qing Zheng
- Department of Physics, Okayama University, Okayama, 700-8530, Japan. .,Institute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter Physics, 100190, Beijing, China.
| |
Collapse
|
26
|
Liu ZH, Yaresko AN, Li Y, Dai PC, Zhang H, Büchner B, Lin CT, Borisenko SV. Observation of the weak electronic correlations in KFeCoAs 2 (3d 6): an isoelectronic to the parent compounds of 122 series of iron pnictides BaFe 2As 2. J Phys Condens Matter 2017; 29:085503. [PMID: 27991428 DOI: 10.1088/1361-648x/aa5486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using the angle-resolved photoemission spectroscopy and band structure calculations we study the electronic structure of KFeCoAs2, which is isoelectronic to the parent material of 122 series of iron-based superconductors BaFe2As2. Although band structure calculations predict nearly identical dispersions of the electronic states in both compounds, experiment reveals drastic differences in both the global renormalization and Fermi surfaces. On the basis of the comparison of electronic structures of these two isoelectronic compounds, we demonstrate local magnetic correlations as a vital role for the peculiar low-energy electron dynamics of iron-based superconductors.
Collapse
Affiliation(s)
- Z H Liu
- Institute for Solid State Research, IFW Dresden, D-01171 Dresden, Germany. State Key Laboratory of Functional Materials for Informatic, SIMIT, Chinese Academy of Sciences, Shanghai 200050, People's Repubic of China
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Schmidt CA, Ryan TE, Lin CT, Inigo MMR, Green TD, Brault JJ, Spangenburg EE, McClung JM. Diminished force production and mitochondrial respiratory deficits are strain-dependent myopathies of subacute limb ischemia. J Vasc Surg 2016; 65:1504-1514.e11. [PMID: 28024849 DOI: 10.1016/j.jvs.2016.04.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/17/2016] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Reduced skeletal muscle mitochondrial function might be a contributing mechanism to the myopathy and activity based limitations that typically plague patients with peripheral arterial disease (PAD). We hypothesized that mitochondrial dysfunction, myofiber atrophy, and muscle contractile deficits are inherently determined by the genetic background of regenerating ischemic mouse skeletal muscle, similar to how patient genetics affect the distribution of disease severity with clinical PAD. METHODS Genetically ischemia protected (C57BL/6) and susceptible (BALB/c) mice underwent either unilateral subacute hind limb ischemia (SLI) or myotoxic injury (cardiotoxin) for 28 days. Limbs were monitored for blood flow and tissue oxygen saturation and tissue was collected for the assessment of histology, muscle contractile force, gene expression, mitochondrial content, and respiratory function. RESULTS Despite similar tissue O2 saturation and mitochondrial content between strains, BALB/c mice suffered persistent ischemic myofiber atrophy (55.3% of C57BL/6) and muscle contractile deficits (approximately 25% of C57BL/6 across multiple stimulation frequencies). SLI also reduced BALB/c mitochondrial respiratory capacity, assessed in either isolated mitochondria (58.3% of C57BL/6 at SLI on day (d)7, 59.1% of C57BL/6 at SLI d28 across multiple conditions) or permeabilized myofibers (38.9% of C57BL/6 at SLI d7; 76.2% of C57BL/6 at SLI d28 across multiple conditions). SLI also resulted in decreased calcium retention capacity (56.0% of C57BL/6) in BALB/c mitochondria. Nonischemic cardiotoxin injury revealed similar recovery of myofiber area, contractile force, mitochondrial respiratory capacity, and calcium retention between strains. CONCLUSIONS Ischemia-susceptible BALB/c mice suffered persistent muscle atrophy, impaired muscle function, and mitochondrial respiratory deficits during SLI. Interestingly, parental strain susceptibility to myopathy appears specific to regenerative insults including an ischemic component. Our findings indicate that the functional deficits that plague PAD patients could include mitochondrial respiratory deficits genetically inherent to the regenerating muscle myofibers.
Collapse
Affiliation(s)
- Cameron A Schmidt
- Department of Physiology, East Carolina University, Greenville, NC; Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC
| | - Terence E Ryan
- Department of Physiology, East Carolina University, Greenville, NC; Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC
| | - Chien-Te Lin
- Department of Physiology, East Carolina University, Greenville, NC; Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC
| | - Melissa M R Inigo
- Department of Physiology, East Carolina University, Greenville, NC; Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC
| | - Tom D Green
- Department of Physiology, East Carolina University, Greenville, NC; Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC
| | - Jeffrey J Brault
- Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC; Department of Kinesiology, East Carolina University, Greenville, NC
| | - Espen E Spangenburg
- Department of Physiology, East Carolina University, Greenville, NC; Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC
| | - Joseph M McClung
- Department of Physiology, East Carolina University, Greenville, NC; Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC.
| |
Collapse
|
28
|
Fisher-Wellman KH, Ryan TE, Smith CD, Gilliam LAA, Lin CT, Reese LR, Torres MJ, Neufer PD. A Direct Comparison of Metabolic Responses to High-Fat Diet in C57BL/6J and C57BL/6NJ Mice. Diabetes 2016; 65:3249-3261. [PMID: 27495226 PMCID: PMC5079634 DOI: 10.2337/db16-0291] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 07/28/2016] [Indexed: 02/02/2023]
Abstract
Although nicotinamide nucleotide transhydrogenase (NNT)-deficient C57BL/6J (6J) mice are known to be highly susceptible to diet-induced metabolic disease, this notion stems primarily from comparisons of 6J mice to other inbred strains. To date, very few studies have directly compared metabolic disease susceptibility between NNT-deficient 6J mice and NNT-competent C57BL/6 substrains. In this study, comprehensive profiling of the metabolic response to a high-fat/high-sucrose diet (HFD) were compared across time in 6J and C57BL/6NJ (6N) mice. Given that increased peroxide exposure drives insulin resistance, coupled with the fact that NNT regulates peroxide detoxification, it was hypothesized that 6J mice would experience greater derangements in redox homeostasis/metabolic disease upon HFD exposure. Contrary to this, both lines were found to be highly susceptible to diet-induced metabolic disease, as evidenced by impairments in glucose tolerance as early as 24 h into the HFD. Moreover, various markers of the metabolic syndrome, as well as peroxide stress, were actually blunted, rather than exacerbated, in the 6J mice, likely reflecting compensatory increases in alterative redox-buffering pathways. Together, these data provide evidence that the susceptibility to HFD-induced metabolic disease is similar in the 6J and 6N substrains. Given the numerous genetic variances in the 6J stain, including loss of NNT function, these findings suggest that the 6N substrain is the more logical and representative genetic background model for metabolic studies.
Collapse
Affiliation(s)
- Kelsey H Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Duke Molecular Physiology Institute, Duke University, Durham, NC
| | - Terence E Ryan
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Department of Physiology, East Carolina University, Greenville, NC
| | - Cody D Smith
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Department of Physiology, East Carolina University, Greenville, NC
| | - Laura A A Gilliam
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Department of Physiology, East Carolina University, Greenville, NC
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Department of Physiology, East Carolina University, Greenville, NC
| | - Lauren R Reese
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Department of Physiology, East Carolina University, Greenville, NC
| | - Maria J Torres
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Department of Kinesiology, East Carolina University, Greenville, NC
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC
- Department of Physiology, East Carolina University, Greenville, NC
- Department of Kinesiology, East Carolina University, Greenville, NC
| |
Collapse
|
29
|
Gilliam LAA, Lark DS, Reese LR, Torres MJ, Ryan TE, Lin CT, Cathey BL, Neufer PD. Targeted overexpression of mitochondrial catalase protects against cancer chemotherapy-induced skeletal muscle dysfunction. Am J Physiol Endocrinol Metab 2016; 311:E293-301. [PMID: 27329802 PMCID: PMC5005971 DOI: 10.1152/ajpendo.00540.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 06/16/2016] [Indexed: 11/22/2022]
Abstract
The loss of strength in combination with constant fatigue is a burden on cancer patients undergoing chemotherapy. Doxorubicin, a standard chemotherapy drug used in the clinic, causes skeletal muscle dysfunction and increases mitochondrial H2O2 We hypothesized that the combined effect of cancer and chemotherapy in an immunocompetent breast cancer mouse model (E0771) would compromise skeletal muscle mitochondrial respiratory function, leading to an increase in H2O2-emitting potential and impaired muscle function. Here, we demonstrate that cancer chemotherapy decreases mitochondrial respiratory capacity supported with complex I (pyruvate/glutamate/malate) and complex II (succinate) substrates. Mitochondrial H2O2-emitting potential was altered in skeletal muscle, and global protein oxidation was elevated with cancer chemotherapy. Muscle contractile function was impaired following exposure to cancer chemotherapy. Genetically engineering the overexpression of catalase in mitochondria of muscle attenuated mitochondrial H2O2 emission and protein oxidation, preserving mitochondrial and whole muscle function despite cancer chemotherapy. These findings suggest mitochondrial oxidants as a mediator of cancer chemotherapy-induced skeletal muscle dysfunction.
Collapse
Affiliation(s)
- Laura A A Gilliam
- East Carolina Diabetes and Obesity Institute, Department of Physiology, and
| | - Daniel S Lark
- East Carolina Diabetes and Obesity Institute, Department of Kinesiology, East Carolina University, Greenville, North Carolina
| | - Lauren R Reese
- East Carolina Diabetes and Obesity Institute, Department of Physiology, and
| | - Maria J Torres
- East Carolina Diabetes and Obesity Institute, Department of Kinesiology, East Carolina University, Greenville, North Carolina
| | - Terence E Ryan
- East Carolina Diabetes and Obesity Institute, Department of Physiology, and
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, Department of Physiology, and
| | - Brook L Cathey
- East Carolina Diabetes and Obesity Institute, Department of Physiology, and
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, Department of Physiology, and Department of Kinesiology, East Carolina University, Greenville, North Carolina
| |
Collapse
|
30
|
Lark DS, Torres MJ, Lin CT, Ryan TE, Anderson EJ, Neufer PD. Direct real-time quantification of mitochondrial oxidative phosphorylation efficiency in permeabilized skeletal muscle myofibers. Am J Physiol Cell Physiol 2016; 311:C239-45. [PMID: 27335172 DOI: 10.1152/ajpcell.00124.2016] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/11/2016] [Indexed: 11/22/2022]
Abstract
Oxidative phosphorylation (OXPHOS) efficiency, defined as the ATP-to-O ratio, is a critical feature of mitochondrial function that has been implicated in health, aging, and disease. To date, however, the methods to measure ATP/O have primarily relied on indirect approaches or entail parallel rather than simultaneous determination of ATP synthesis and O2 consumption rates. The purpose of this project was to develop and validate an approach to determine the ATP/O ratio in permeabilized fiber bundles (PmFBs) from simultaneous measures of ATP synthesis (JATP) and O2 consumption (JO2 ) rates in real time using a custom-designed apparatus. JO2 was measured via a polarigraphic oxygen sensor and JATP via fluorescence using an enzyme-linked assay system (hexokinase II, glucose-6-phosphate dehydrogenase) linked to NADPH production. Within the dynamic linear range of the assay system, ADP-stimulated increases in steady-state JATP mirrored increases in steady-state JO2 (r(2) = 0.91, P < 0.0001, n = 57 data points). ATP/O ratio was less than one under low rates of respiration (15 μM ADP) but increased to more than two at moderate (200 μM ADP) and maximal (2,000 μM ADP) rates of respiration with an interassay coefficient of variation of 24.03, 16.72, and 11.99%, respectively. Absolute and relative (to mechanistic) ATP/O ratios were lower in PmFBs (2.09 ± 0.251, 84%) compared with isolated mitochondria (2.44 ± 0.124, 98%). ATP/O ratios in PmFBs were not affected by the activity of adenylate kinase or creatine kinase. These findings validate an enzyme-linked respiratory clamp system for measuring OXPHOS efficiency in PmFBs and provide evidence that OXPHOS efficiency increases as energy demand increases.
Collapse
Affiliation(s)
- Daniel S Lark
- Department of Kinesiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Maria J Torres
- Department of Kinesiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Chien-Te Lin
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Terence E Ryan
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Ethan J Anderson
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; and East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - P Darrell Neufer
- Department of Kinesiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| |
Collapse
|
31
|
Affiliation(s)
- Zuzanna Czernik
- Hospital Medicine Section, Division of General Internal Medicine, University of Colorado School of Medicine, Aurora
| | - C T Lin
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora
| |
Collapse
|
32
|
Yu G, Zhang GY, Ryu GH, Lin CT. Structure and superconductivity of (Li1-x Fe x )OHFeSe single crystals grown using A x Fe2-y Se2 (A = K, Rb, and Cs) as precursors. J Phys Condens Matter 2016; 28:015701. [PMID: 26656943 DOI: 10.1088/0953-8984/28/1/015701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present results on the hydrothermal growth of ([Formula: see text])OHFeSe single crystals using floating-zone-grown [Formula: see text] (A = K, Rb, and Cs) as precursors. The growth proceeds by the hydrothermal ion exchange of Li/Fe-O-H for K, Rb, and Cs, resulting in a stacking layer of ([Formula: see text])OH sandwiched between the FeSe layers. Optimal growth parameters are achieved using high quality A 0.80Fe1.81Se2 single crystals added to the mixtures of LiOH, H2O, Fe and C(NH2)2Se in an autoclave and subsequently heated to 120 °C for 2 d, to obtain highest quality single crystals. The obtained crystals have lateral dimensions up to centimeters, with the final size related to that of the precursor crystal used. All ([Formula: see text])OHFeSe single crystals show a superconducting transition temperature T c > 42 K, regardless of the phase of the precursor such as superconducting K0.80Fe1.81Se2 (T c = 29.31 K) or non-superconducting Rb0.80Fe1.81Se2 or poor-superconducting Cs0.80Fe1.81Se2 (T c = 28.67 K). The T c and transition width ΔT vary in the obtained single crystals, due to the inhomogeneity of the ionic exchange. X-ray diffraction analysis demonstrates that the 245 insulating phase is absent in the ion-exchanged single crystals, while it is observed in the [Formula: see text] precursors. Comparative studies of the structure, magnetization, and superconductivity on the parent A 0.80Fe1.81Se2 and the ion-exchanged ([Formula: see text])OHFeSe crystals are discussed. A phase diagram including antiferromagnetic spin density wave and superconducting phases is also proposed.
Collapse
Affiliation(s)
- G Yu
- Max Planck Institute for Solid State Research, D 70569 Stuttgart, Germany. Shijiazhuang Tiedao University, Shijiazhuang 050043, People's Republic of China
| | | | | | | |
Collapse
|
33
|
Lark DS, Reese LR, Ryan TE, Torres MJ, Smith CD, Lin CT, Neufer PD. Protein Kinase A Governs Oxidative Phosphorylation Kinetics and Oxidant Emitting Potential at Complex I. Front Physiol 2015; 6:332. [PMID: 26635618 PMCID: PMC4646981 DOI: 10.3389/fphys.2015.00332] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 11/02/2015] [Indexed: 11/24/2022] Open
Abstract
The mitochondrial electron transport system (ETS) is responsible for setting and maintaining both the energy and redox charges throughout the cell. Reversible phosphorylation of mitochondrial proteins, particularly via the soluble adenylyl cyclase (sAC)/cyclic AMP (cAMP)/Protein kinase A (PKA) axis, has recently been revealed as a potential mechanism regulating the ETS. However, the governance of cAMP/PKA signaling and its implications on ETS function are incompletely understood. In contrast to prior reports using exogenous bicarbonate, we provide evidence that endogenous CO2 produced by increased tricarboxylic acid (TCA) cycle flux is insufficient to increase mitochondrial cAMP levels, and that exogenous addition of membrane permeant 8Br-cAMP does not enhance mitochondrial respiratory capacity. We also report important non-specific effects of commonly used inhibitors of sAC which preclude their use in studies of mitochondrial function. In isolated liver mitochondria, inhibition of PKA reduced complex I-, but not complex II-supported respiratory capacity. In permeabilized myofibers, inhibition of PKA lowered both the Km and Vmax for complex I-supported respiration as well as succinate-supported H2O2 emitting potential. In summary, the data provided here improve our understanding of how mitochondrial cAMP production is regulated, illustrate a need for better tools to examine the impact of sAC activity on mitochondrial biology, and suggest that cAMP/PKA signaling contributes to the governance of electron flow through complex I of the ETS.
Collapse
Affiliation(s)
- Daniel S Lark
- East Carolina Diabetes and Obesity Institute Greenville, NC, USA ; Department of Kinesiology, East Carolina University Greenville, NC, USA
| | - Lauren R Reese
- East Carolina Diabetes and Obesity Institute Greenville, NC, USA ; Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - Terence E Ryan
- East Carolina Diabetes and Obesity Institute Greenville, NC, USA ; Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - Maria J Torres
- East Carolina Diabetes and Obesity Institute Greenville, NC, USA ; Department of Kinesiology, East Carolina University Greenville, NC, USA
| | - Cody D Smith
- East Carolina Diabetes and Obesity Institute Greenville, NC, USA ; Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute Greenville, NC, USA ; Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute Greenville, NC, USA ; Department of Kinesiology, East Carolina University Greenville, NC, USA ; Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA
| |
Collapse
|
34
|
Lin WT, Chang CH, Cheng CY, Chen MC, Wen YR, Lin CT, Lin CW. Effects of low amplitude pulsed radiofrequency stimulation with different waveform in rats for neuropathic pain. Annu Int Conf IEEE Eng Med Biol Soc 2015; 2013:3590-3. [PMID: 24110506 DOI: 10.1109/embc.2013.6610319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Pulsed-radiofrequency (PRF) electrical stimulation has been widely used for chronic pain treatment. It has been demonstrated with advantages of low temperature over traditional continuous radiofrequency (CRF) lesions with higher amplitude and mono polar electrode to treat pain in clinics (frequency 500 KHz, Pulse duration 20 msec, Amplitude 45 V, Treatment 2 min). We compare the effects of different pulse waveforms and PRF parameters (Pulse duration 25 ms, Treatment duration 5 min, low amplitude of 2.5/1.25 V) with a miniature bi-polar electrode on Dorsal root ganglion (DRG). The pain relief effect due to PRF is evaluated by using Von Frey method for the pain threshold index based on behavior response to mechanical stimulus of various strengths. Experimental results of Von Frey Score show that the sinusoidal group has higher responses than the square wave one. Both fast and secondary expressed proteins of c-fos and pp38 are measured from spinal cord tissue sectioning slides to characterize the pain associated inflammatory responses and their responses due to PRF stimulation.
Collapse
|
35
|
|
36
|
Kang L, Dai C, Lustig ME, Bonner JS, Mayes WH, Mokshagundam S, James FD, Thompson CS, Lin CT, Perry CGR, Anderson EJ, Neufer PD, Wasserman DH, Powers AC. Heterozygous SOD2 deletion impairs glucose-stimulated insulin secretion, but not insulin action, in high-fat-fed mice. Diabetes 2014; 63:3699-710. [PMID: 24947366 PMCID: PMC4207395 DOI: 10.2337/db13-1845] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Elevated reactive oxygen species (ROS) are linked to insulin resistance and islet dysfunction. Manganese superoxide dismutase (SOD2) is a primary defense against mitochondrial oxidative stress. To test the hypothesis that heterozygous SOD2 deletion impairs glucose-stimulated insulin secretion (GSIS) and insulin action, wild-type (sod2(+/+)) and heterozygous knockout mice (sod2(+/-)) were fed a chow or high-fat (HF) diet, which accelerates ROS production. Hyperglycemic (HG) and hyperinsulinemic-euglycemic (HI) clamps were performed to assess GSIS and insulin action in vivo. GSIS during HG clamps was equal in chow-fed sod2(+/-) and sod2(+/+) but was markedly decreased in HF-fed sod2(+/-). Remarkably, this impairment was not paralleled by reduced HG glucose infusion rate (GIR). Decreased GSIS in HF-fed sod2(+/-) was associated with increased ROS, such as superoxide ion. Surprisingly, insulin action determined by HI clamps did not differ between sod2(+/-) and sod2(+/+) of either diet. Since insulin action was unaffected, we hypothesized that the unchanged HG GIR in HF-fed sod2(+/-) was due to increased glucose effectiveness. Increased GLUT-1, hexokinase II, and phospho-AMPK protein in muscle of HF-fed sod2(+/-) support this hypothesis. We conclude that heterozygous SOD2 deletion in mice, a model that mimics SOD2 changes observed in diabetic humans, impairs GSIS in HF-fed mice without affecting insulin action.
Collapse
Affiliation(s)
- Li Kang
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, U.K.
| | - Chunhua Dai
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, TN
| | - Mary E Lustig
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Jeffrey S Bonner
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Wesley H Mayes
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Shilpa Mokshagundam
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Freyja D James
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Courtney S Thompson
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, TN
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - Christopher G R Perry
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - Ethan J Anderson
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN
| | - Alvin C Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, TN Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN
| |
Collapse
|
37
|
Ryan TE, Brophy P, Lin CT, Hickner RC, Neufer PD. Assessment of in vivo skeletal muscle mitochondrial respiratory capacity in humans by near-infrared spectroscopy: a comparison with in situ measurements. J Physiol 2014; 592:3231-41. [PMID: 24951618 DOI: 10.1113/jphysiol.2014.274456] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The present study aimed to compare in vivo measurements of skeletal muscle mitochondrial respiratory capacity made using near-infrared spectroscopy (NIRS) with the current gold standard, namely in situ measurements of high-resolution respirometry performed in permeabilized muscle fibres prepared from muscle biopsies. Mitochondrial respiratory capacity was determined in 21 healthy adults in vivo using NIRS to measure the recovery kinetics of muscle oxygen consumption following a ∼15 s isometric contraction of the vastus lateralis muscle. Maximal ADP-stimulated (State 3) respiration was measured in permeabilized muscle fibres using high-resolution respirometry with sequential titrations of saturating concentrations of metabolic substrates. Overall, the in vivo and in situ measurements were strongly correlated (Pearson's r = 0.61-0.74, all P < 0.01). Bland-Altman plots also showed good agreement with no indication of bias. The results indicate that in vivo NIRS corresponds well with the current gold standard, in situ high-resolution respirometry, for assessing mitochondrial respiratory capacity.
Collapse
Affiliation(s)
- Terence E Ryan
- Department of Physiology, East Carolina University, Greenville, NC, USA East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Patricia Brophy
- Department of Physiology, East Carolina University, Greenville, NC, USA East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Chien-Te Lin
- Department of Physiology, East Carolina University, Greenville, NC, USA East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Robert C Hickner
- Department of Physiology, East Carolina University, Greenville, NC, USA Department of Kinesiology, East Carolina University, Greenville, NC, USA East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA Human Performance Laboratory, East Carolina University, Greenville, NC, USA Center for Health Disparities, East Carolina University, Greenville, NC, USA School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - P Darrell Neufer
- Department of Physiology, East Carolina University, Greenville, NC, USA Department of Kinesiology, East Carolina University, Greenville, NC, USA East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA Human Performance Laboratory, East Carolina University, Greenville, NC, USA
| |
Collapse
|
38
|
Hsueh WJ, Chang CH, Lin CT. Exciton photoluminescence in resonant quasi-periodic Thue-Morse quantum wells. Opt Lett 2014; 39:489-492. [PMID: 24487847 DOI: 10.1364/ol.39.000489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This Letter investigates exciton photoluminescence (PL) in resonant quasi-periodic Thue-Morse quantum wells (QWs). The results show that the PL properties of quasi-periodic Thue-Morse QWs are quite different from those of resonant Fibonacci QWs. The maximum and minimum PL intensities occur under the anti-Bragg and Bragg conditions, respectively. The maxima of the PL intensity gradually decline when the filling factor increases from 0.25 to 0.5. Accordingly, the squared electric field at the QWs decreases as the Thue-Morse QW deviates from the anti-Bragg condition.
Collapse
|
39
|
Fisher-Wellman KH, Gilliam LAA, Lin CT, Cathey BL, Lark DS, Darrell Neufer P. Mitochondrial glutathione depletion reveals a novel role for the pyruvate dehydrogenase complex as a key H2O2-emitting source under conditions of nutrient overload. Free Radic Biol Med 2013; 65:1201-1208. [PMID: 24056031 PMCID: PMC3965186 DOI: 10.1016/j.freeradbiomed.2013.09.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/26/2013] [Accepted: 09/13/2013] [Indexed: 11/25/2022]
Abstract
Once regarded as a "by-product" of aerobic metabolism, the production of superoxide/H2O2 is now understood to be a highly specialized and extensively regulated process responsible for exerting control over a vast number of thiol-containing proteins, collectively referred to as the redox-sensitive proteome. Although disruptions within this process, secondary to elevated peroxide exposure, have been linked to disease, the sources and mechanisms regulating increased peroxide burden remain poorly defined and as such are difficult to target using pharmacotherapy. Here we identify the pyruvate dehydrogenase complex (PDC) as a key source of H2O2 within skeletal muscle mitochondria under conditions of depressed glutathione redox buffering integrity. Treatment of permeabilized myofibers with varying concentrations of the glutathione-depleting agent 1-chloro-2,4-dinitrobenzene led to a dose-dependent increase in pyruvate-supported JH2O2 emission (the flux of H2O2 diffusing out of the mitochondrial matrix into the surrounding assay medium), with emission rates eventually rising to exceed those of all substrate combinations tested. This striking sensitivity to glutathione depletion was observed in permeabilized fibers prepared from multiple species and was specific to PDC. Physiological oxidation of the cellular glutathione pool after high-fat feeding in rodents was found to elevate PDC JH2O2 emission, as well as increasing the sensitivity of the complex to GSH depletion. These findings reveal PDC as a potential major site of H2O2 production that is extremely sensitive to mitochondrial glutathione redox status.
Collapse
Affiliation(s)
- Kelsey H Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA.
| | - Laura A A Gilliam
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA
| | - Brook L Cathey
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA
| | - Daniel S Lark
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
| |
Collapse
|
40
|
Gilliam LAA, Fisher-Wellman KH, Lin CT, Maples JM, Cathey BL, Neufer PD. The anticancer agent doxorubicin disrupts mitochondrial energy metabolism and redox balance in skeletal muscle. Free Radic Biol Med 2013; 65:988-996. [PMID: 24017970 PMCID: PMC3859698 DOI: 10.1016/j.freeradbiomed.2013.08.191] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 12/25/2022]
Abstract
The combined loss of muscle strength and constant fatigue are disabling symptoms for cancer patients undergoing chemotherapy. Doxorubicin, a standard chemotherapy drug used in the clinic, causes skeletal muscle dysfunction and premature fatigue along with an increase in reactive oxygen species (ROS). As mitochondria represent a primary source of oxidant generation in muscle, we hypothesized that doxorubicin could negatively affect mitochondria by inhibiting respiratory capacity, leading to an increase in H2O2-emitting potential. Here we demonstrate a biphasic response of skeletal muscle mitochondria to a single doxorubicin injection (20mg/kg). Initially at 2h doxorubicin inhibits both complex I- and II-supported respiration and increases H2O2 emission, both of which are partially restored after 24h. The relationship between oxygen consumption and membrane potential (ΔΨ) is shifted to the right at 24h, indicating elevated reducing pressure within the electron transport system (ETS). Respiratory capacity is further decreased at a later time point (72 h) along with H2O2-emitting potential and an increased sensitivity to mitochondrial permeability transition pore (mPTP) opening. These novel findings suggest a role for skeletal muscle mitochondria as a potential underlying cause of doxorubicin-induced muscle dysfunction.
Collapse
Affiliation(s)
- Laura A A Gilliam
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA.
| | - Kelsey H Fisher-Wellman
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA
| | - Jill M Maples
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
| | - Brook L Cathey
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA; Department of Physiology, East Carolina University, Greenville, NC 27858, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27858, USA
| |
Collapse
|
41
|
Li Y, Le Tacon M, Matiks Y, Boris AV, Loew T, Lin CT, Chen L, Chan MK, Dorow C, Ji L, Barišić N, Zhao X, Greven M, Keimer B. Doping-dependent photon scattering resonance in the model high-temperature superconductor HgBa2CuO4+δ revealed by Raman scattering and optical ellipsometry. Phys Rev Lett 2013; 111:187001. [PMID: 24237551 DOI: 10.1103/physrevlett.111.187001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Indexed: 06/02/2023]
Abstract
We study the model high-temperature superconductor HgBa(2)CuO(4+δ) with electronic Raman scattering and optical ellipsometry over a wide doping range. The dependence of the resonant Raman cross section on the incident photon energy changes drastically as a function of doping, in a manner that corresponds to a rearrangement of the interband optical transitions seen with ellipsometry. This doping-dependent Raman resonance allows us to reconcile the apparent discrepancy between Raman and x-ray detection of magnetic fluctuations in superconducting cuprates. Intriguingly, the strongest variation occurs across the doping level where the antinodal superconducting gap appears to reach its maximum.
Collapse
Affiliation(s)
- Yuan Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China and Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Li MT, Chen L, Li ZW, Ryu GH, Lin CT, Zhang JC. Enhancement of phase separation and superconductivity in Mn-doped K0.8Fe2-yMnySe2 crystals. J Phys Condens Matter 2013; 25:335701. [PMID: 23880791 DOI: 10.1088/0953-8984/25/33/335701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Single crystals of K0.8Fe2-yMnySe2 with slight Mn doping have been grown by a self-flux method. X-ray diffraction measurements show enhanced phase separation with increasing Mn doping in the compounds. The superconducting transition temperature increases to Tc,onset ∼ 46.1 K for the sample with y ∼ 0.03, as observed by electrical transport measurements. Our results demonstrate that the doping of Mn does not suppress the superconductivity, and on the contrary increases the superconducting shield fraction and transition temperature, an effect which may originate from the Mn dopant's high preference to fill into iron vacancies in the Mn-doped samples. It suggests that the Mn dopant can induce a local lattice strain or distortion that profitably modifies the microstructure of the superconducting/metallic phase, leading to superconductivity of the compound.
Collapse
Affiliation(s)
- M T Li
- Department of Physics, Shanghai University, Shanghai 200444, People's Republic of China
| | | | | | | | | | | |
Collapse
|
43
|
Kang L, Lustig ME, Bonner JS, Lee-Young RS, Mayes WH, James FD, Lin CT, Perry CGR, Anderson EJ, Neufer PD, Wasserman DH. Mitochondrial antioxidative capacity regulates muscle glucose uptake in the conscious mouse: effect of exercise and diet. J Appl Physiol (1985) 2012; 113:1173-83. [PMID: 22653994 DOI: 10.1152/japplphysiol.01344.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The objective of this study was to test the hypothesis that exercise-stimulated muscle glucose uptake (MGU) is augmented by increasing mitochondrial reactive oxygen species (mtROS) scavenging capacity. This hypothesis was tested in genetically altered mice fed chow or a high-fat (HF) diet that accelerates mtROS formation. Mice overexpressing SOD2 (sod2(Tg)), mitochondria-targeted catalase (mcat(Tg)), and combined SOD2 and mCAT (mtAO) were used to increase mtROS scavenging. mtROS was assessed by the H(2)O(2) emitting potential (JH(2)O(2)) in muscle fibers. sod2(Tg) did not decrease JH(2)O(2) in chow-fed mice, but decreased JH(2)O(2) in HF-fed mice. mcat(Tg) and mtAO decreased JH(2)O(2) in both chow- and HF-fed mice. In parallel, the ratio of reduced to oxidized glutathione (GSH/GSSG) was unaltered in sod2(Tg) in chow-fed mice, but was increased in HF-fed sod2(Tg) and both chow- and HF-fed mcat(Tg) and mtAO. Nitrotyrosine, a marker of NO-dependent, reactive nitrogen species (RNS)-induced nitrative stress, was decreased in both chow- and HF-fed sod2(Tg), mcat(Tg), and mtAO mice. This effect was not changed with exercise. Kg, an index of MGU was assessed using 2-[(14)C]-deoxyglucose during exercise. In chow-fed mice, sod2(Tg), mcat(Tg), and mtAO increased exercise Kg compared with wild types. Exercise Kg was also augmented in HF-fed sod2(Tg) and mcat(Tg) mice but unchanged in HF-fed mtAO mice. In conclusion, mtROS scavenging is a key regulator of exercise-mediated MGU and this regulation depends on nutritional state.
Collapse
Affiliation(s)
- Li Kang
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Lin CT, Fisher-Wellman KH, Perry CG, Kozy R, Lark DS, Gilliam LAA, Smith CD, Neufer DP. Low Intensity Exercise Attenuates Acute Lipid Loading‐Induced Alterations in Mitochondrial Function in Rat Skeletal Muscle. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1144.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Chien-Te Lin
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- KinesiologyEast Carolina UniversityGreenvilleNC
| | - Kelsey H. Fisher-Wellman
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- KinesiologyEast Carolina UniversityGreenvilleNC
| | - Christopher G.R. Perry
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- KinesiologyEast Carolina UniversityGreenvilleNC
| | - Rachel Kozy
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- KinesiologyEast Carolina UniversityGreenvilleNC
| | - Daniel S. Lark
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- KinesiologyEast Carolina UniversityGreenvilleNC
| | - Laura A. A. Gilliam
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- PhysiologyEast Carolina UniversityGreenvilleNC
| | - Cody D. Smith
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- PhysiologyEast Carolina UniversityGreenvilleNC
| | - Darrell P. Neufer
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- PhysiologyEast Carolina UniversityGreenvilleNC
| |
Collapse
|
45
|
Fisher-Wellman KH, Lin CT, Gilliam LAA, Cathey BL, Neufer PD. Mitochondrial glutathione depletion reveals a novel role for pyruvate dehydrogenase as a key H
2
O
2
emitting source. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1144.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kelsey H Fisher-Wellman
- KinesiologyEast Carolina UniversityGreenvilleNC
- East Carolina Diabetes and Obesity InstituteGreenvilleNC
| | - Chien-Te Lin
- KinesiologyEast Carolina UniversityGreenvilleNC
- East Carolina Diabetes and Obesity InstituteGreenvilleNC
| | - Laura A. A. Gilliam
- KinesiologyEast Carolina UniversityGreenvilleNC
- East Carolina Diabetes and Obesity InstituteGreenvilleNC
| | - Brook L. Cathey
- KinesiologyEast Carolina UniversityGreenvilleNC
- East Carolina Diabetes and Obesity InstituteGreenvilleNC
| | - P. Darrell Neufer
- KinesiologyEast Carolina UniversityGreenvilleNC
- East Carolina Diabetes and Obesity InstituteGreenvilleNC
| |
Collapse
|
46
|
Affiliation(s)
- Laura A. A. Gilliam
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- Department of KinesiologyEast Carolina UniversityGreenvilleNC
| | - Kelsey H. Fisher-Wellman
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- Department of KinesiologyEast Carolina UniversityGreenvilleNC
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- Department of KinesiologyEast Carolina UniversityGreenvilleNC
| | - Jill M. Maples
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- Department of KinesiologyEast Carolina UniversityGreenvilleNC
| | - P. Darrell Neufer
- East Carolina Diabetes and Obesity InstituteEast Carolina UniversityGreenvilleNC
- Department of PhysiologyEast Carolina UniversityGreenvilleNC
| |
Collapse
|
47
|
Kwak HB, Thalacker-Mercer A, Anderson EJ, Lin CT, Kane DA, Lee NS, Cortright RN, Bamman MM, Neufer PD. Simvastatin impairs ADP-stimulated respiration and increases mitochondrial oxidative stress in primary human skeletal myotubes. Free Radic Biol Med 2012; 52:198-207. [PMID: 22080086 PMCID: PMC3313473 DOI: 10.1016/j.freeradbiomed.2011.10.449] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 10/14/2011] [Accepted: 10/17/2011] [Indexed: 11/19/2022]
Abstract
Statins, the widely prescribed cholesterol-lowering drugs for the treatment of cardiovascular disease, cause adverse skeletal muscle side effects ranging from fatigue to fatal rhabdomyolysis. The purpose of this study was to determine the effects of simvastatin on mitochondrial respiration, oxidative stress, and cell death in differentiated primary human skeletal muscle cells (i.e., myotubes). Simvastatin induced a dose-dependent decrease in viability of proliferating and differentiating primary human muscle precursor cells, and a similar dose-dependent effect was noted in differentiated myoblasts and myotubes. Additionally, there were decreases in myotube number and size following 48 h of simvastatin treatment (5 μM). In permeabilized myotubes, maximal ADP-stimulated oxygen consumption, supported by palmitoylcarnitine+malate (PCM, complex I and II substrates) and glutamate+malate (GM, complex I substrates), was 32-37% lower (P<0.05) in simvastatin-treated (5 μM) vs control myotubes, providing evidence of impaired respiration at complex I. Mitochondrial superoxide and hydrogen peroxide generation were significantly greater in the simvastatin-treated human skeletal myotube cultures compared to control. In addition, simvastatin markedly increased protein levels of Bax (proapoptotic, +53%) and Bcl-2 (antiapoptotic, +100%, P<0.05), mitochondrial PTP opening (+44%, P<0.05), and TUNEL-positive nuclei in human skeletal myotubes, demonstrating up-regulation of mitochondrial-mediated myonuclear apoptotic mechanisms. These data demonstrate that simvastatin induces myotube atrophy and cell loss associated with impaired ADP-stimulated maximal mitochondrial respiratory capacity, mitochondrial oxidative stress, and apoptosis in primary human skeletal myotubes, suggesting that mitochondrial dysfunction may underlie human statin-induced myopathy.
Collapse
Affiliation(s)
- Hyo-Bum Kwak
- Department of Kinesiology, East Carolina University, Greenville, NC 27834
- Department of Physiology, East Carolina University, Greenville, NC 27834
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834
| | - Anna Thalacker-Mercer
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, AL 35294
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Ethan J. Anderson
- Department of Cardiovascular Sciences, East Carolina University, Greenville, NC 27834
- Department of Pharmacology, East Carolina University, Greenville, NC 27834
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834
| | - Chien-Te Lin
- Department of Kinesiology, East Carolina University, Greenville, NC 27834
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834
| | - Daniel A. Kane
- Department of Kinesiology, East Carolina University, Greenville, NC 27834
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834
| | - Nam-Sihk Lee
- Department of Internal Medicine, East Carolina University, Greenville, NC 27834
| | - Ronald N. Cortright
- Department of Kinesiology, East Carolina University, Greenville, NC 27834
- Department of Physiology, East Carolina University, Greenville, NC 27834
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834
| | - Marcas M. Bamman
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, AL 35294
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - P. Darrell Neufer
- Department of Kinesiology, East Carolina University, Greenville, NC 27834
- Department of Physiology, East Carolina University, Greenville, NC 27834
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834
- Corresponding Author: P. Darrell Neufer, PhD, Department of Physiology, Brody School of Medicine, 6N98, East Carolina University, Greenville, NC 27834, PH: (252) 744-2780, Fax: (252) 744-3460,
| |
Collapse
|
48
|
Raichle M, Reznik D, Lamago D, Heid R, Li Y, Bakr M, Ulrich C, Hinkov V, Hradil K, Lin CT, Keimer B. Highly anisotropic anomaly in the dispersion of the copper-oxygen bond-bending phonon in superconducting YBa2Cu3O7 from inelastic neutron scattering. Phys Rev Lett 2011; 107:177004. [PMID: 22107567 DOI: 10.1103/physrevlett.107.177004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Indexed: 05/31/2023]
Abstract
Motivated by predictions of a substantial contribution of the "buckling" vibration of the CuO(2) layers to d-wave superconductivity in the cuprates, we have performed an inelastic neutron scattering study of this phonon in an array of untwinned crystals of YBa(2)Cu(3)O(7). The data reveal a pronounced softening of the phonon at the in-plane wave vector q=(0,0.3) upon cooling below ~105 K, but no corresponding anomaly at q=(0.3,0). Based on the observed in-plane anisotropy, we argue that the electron-phonon interaction responsible for this anomaly supports an electronic instability associated with a uniaxial charge-density modulation and does not mediate d-wave superconductivity.
Collapse
Affiliation(s)
- M Raichle
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Perry CGR, Kane DA, Lin CT, Kozy R, Cathey BL, Lark DS, Kane CL, Brophy PM, Gavin TP, Anderson EJ, Neufer PD. Inhibiting myosin-ATPase reveals a dynamic range of mitochondrial respiratory control in skeletal muscle. Biochem J 2011; 437:215-22. [PMID: 21554250 PMCID: PMC3863643 DOI: 10.1042/bj20110366] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Assessment of mitochondrial ADP-stimulated respiratory kinetics in PmFBs (permeabilized fibre bundles) is increasingly used in clinical diagnostic and basic research settings. However, estimates of the Km for ADP vary considerably (~20-300 μM) and tend to overestimate respiration at rest. Noting that PmFBs spontaneously contract during respiration experiments, we systematically determined the impact of contraction, temperature and oxygenation on ADP-stimulated respiratory kinetics. BLEB (blebbistatin), a myosin II ATPase inhibitor, blocked contraction under all conditions and yielded high Km values for ADP of >~250 and ~80 μM in red and white rat PmFBs respectively. In the absence of BLEB, PmFBs contracted and the Km for ADP decreased ~2-10-fold in a temperature-dependent manner. PmFBs were sensitive to hyperoxia (increased Km) in the absence of BLEB (contracted) at 30 °C but not 37 °C. In PmFBs from humans, contraction elicited high sensitivity to ADP (Km<100 μM), whereas blocking contraction (+BLEB) and including a phosphocreatine/creatine ratio of 2:1 to mimic the resting energetic state yielded a Km for ADP of ~1560 μM, consistent with estimates of in vivo resting respiratory rates of <1% maximum. These results demonstrate that the sensitivity of muscle to ADP varies over a wide range in relation to contractile state and cellular energy charge, providing evidence that enzymatic coupling of energy transfer within skeletal muscle becomes more efficient in the working state.
Collapse
Affiliation(s)
- Christopher G R Perry
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Yeoh WK, Gault B, Cui XY, Zhu C, Moody MP, Li L, Zheng RK, Li WX, Wang XL, Dou SX, Sun GL, Lin CT, Ringer SP. Direct observation of local potassium variation and its correlation to electronic inhomogeneity in (Ba(1-x)K(x))Fe2As2 pnictide. Phys Rev Lett 2011; 106:247002. [PMID: 21770591 DOI: 10.1103/physrevlett.106.247002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Indexed: 05/31/2023]
Abstract
Local fluctuations in the distribution of dopant atoms are thought to cause the nanoscale electronic disorder or phase separation in pnictide superconductors. Atom probe tomography has enabled the first direct observations of dopant species clustering in a K-doped 122-phase pnictide. First-principles calculations suggest the coexistence of static magnetism and superconductivity on a lattice parameter length scale over a wide range of dopant concentrations. Our results provide evidence for a mixed scenario of phase coexistence and phase separation, depending on local dopant atom distributions.
Collapse
Affiliation(s)
- W K Yeoh
- Australian Centre for Microscopy & Microanalysis, University of Sydney, Sydney, New South Wales, Australia.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|