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Schweitzer GG, Ditzenberger GL, Hughey CC, Finck BN, Martino MR, Pacak CA, Byrne BJ, Cade WT. Elevated liver glycogenolysis mediates higher blood glucose during acute exercise in Barth syndrome. PLoS One 2023; 18:e0290832. [PMID: 37651450 PMCID: PMC10470866 DOI: 10.1371/journal.pone.0290832] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/17/2023] [Indexed: 09/02/2023] Open
Abstract
Barth syndrome (BTHS) is an X-linked recessive genetic disorder due to mutations in the Tafazzin (TAFAZZIN) gene that lead to cardiac and skeletal muscle mitochondrial dysfunction. Previous studies in humans with BTHS demonstrate that the defects in muscle mitochondrial oxidative metabolism result in an enhanced reliance on anaerobic metabolism during exercise to meet energy demands of muscular work. During exercise, the liver normally increases glucose production via glycogenolysis and gluconeogenesis to match the elevated rate of muscle glucose uptake and meet the ATP requirements of working muscle. However, the impact of Tafazzin deficiency on hepatic glucose production and the pathways contributing to hepatic glucose production during exercise is unknown. Therefore, the purpose of this study was to quantify in vivo liver gluconeogenesis and glycogenolysis in Tafazzin knockdown mice at rest and during acute exercise. METHODS Male TAFAZZIN shRNA transgenic (TG) and wild-type (WT) mice completed exhaustive treadmill running protocols to test exercise tolerance. Mice underwent 2H- and 13C-stable isotope infusions at rest and during a 30-minute treadmill running bout to quantify hepatic glucose production and associated nutrient fluxes under sedentary conditions and during acute exercise. Circulating and tissue (skeletal muscle and liver) samples were obtained during and following exercise to assess static metabolite levels. RESULTS TG mice reached exhaustion sooner during exhaustive treadmill running protocols and exhibited higher plasma lactate concentrations after exhaustive exercise compared to WT mice. Arterial glucose levels were comparable between genotypes at rest, but higher in TG mice compared to WT mice during exercise. Consistent with the higher blood glucose, TG mice showed increased endogenous glucose production owing to elevated glycogenolysis compared to WT mice during exercise. Total gluconeogenesis, gluconeogenesis from glycerol, gluconeogenesis from phosphoenolpyruvate, pyruvate cycling, total cataplerosis, and anaplerotic fluxes were similar between TG and WT mice at rest and during exercise. However, lactate dehydrogenase flux and TCA cycle fluxes trended higher in TG mice during exercise. Liver glycogen content in TG was higher in TG vs. controls. CONCLUSION Our data in the Tafazzin knockdown mouse suggest that elevated anaerobic metabolism during rest and exercise previously reported in humans with BTHS are supported by the finding of higher hepatic glycogenolysis.
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Affiliation(s)
- George G. Schweitzer
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Grace L. Ditzenberger
- Doctor of Physical Therapy Division, Duke University School of Medicine, Durham, NC, United States of America
| | - Curtis C. Hughey
- Department of Medicine, Division of Molecular Medicine, University of Minnesota, Minneapolis, MN, United States of America
| | - Brian N. Finck
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Michael R. Martino
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Christina A. Pacak
- Department of Neurology, University of Minnesota School of Medicine, Minneapolis, MN, United States of America
| | - Barry J. Byrne
- Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL, United States of America
| | - William Todd Cade
- Doctor of Physical Therapy Division, Duke University School of Medicine, Durham, NC, United States of America
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, Missouri, United States of America
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Beals JW, Kayser BD, Smith GI, Schweitzer GG, Kirbach K, Kearney ML, Yoshino J, Rahman G, Knight R, Patterson BW, Klein S. Dietary weight loss-induced improvements in metabolic function are enhanced by exercise in people with obesity and prediabetes. Nat Metab 2023; 5:1221-1235. [PMID: 37365374 PMCID: PMC10515726 DOI: 10.1038/s42255-023-00829-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 05/24/2023] [Indexed: 06/28/2023]
Abstract
The additional therapeutic effects of regular exercise during a dietary weight loss program in people with obesity and prediabetes are unclear. Here, we show that whole-body (primarily muscle) insulin sensitivity (primary outcome) was 2-fold greater (P = 0.006) after 10% weight loss induced by calorie restriction plus exercise training (Diet+EX; n = 8, 6 women) than 10% weight loss induced by calorie restriction alone (Diet-ONLY; n = 8, 4 women) in participants in two concurrent studies. The greater improvement in insulin sensitivity was accompanied by increased muscle expression of genes involved in mitochondrial biogenesis, energy metabolism and angiogenesis (secondary outcomes) in the Diet+EX group. There were no differences between groups in plasma branched-chain amino acids or markers of inflammation, and both interventions caused similar changes in the gut microbiome. Few adverse events were reported. These results demonstrate that regular exercise during a diet-induced weight loss program has profound additional metabolic benefits in people with obesity and prediabetes.Trial Registration: ClinicalTrials.gov (NCT02706262 and NCT02706288).
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Affiliation(s)
- Joseph W Beals
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - Brandon D Kayser
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
- Genentech, South San Francisco, CA, USA
| | - Gordon I Smith
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - George G Schweitzer
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - Kyleigh Kirbach
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - Monica L Kearney
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
- Department of Kinesiology, Nutrition, & Recreation, Southeast Missouri State University, Cape Girardeau, MO, USA
| | - Jun Yoshino
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
- Division of Endocrinology, Metabolism and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Gibraan Rahman
- Department of Pediatrics, University of California, San Diego, CA, USA
- Department of Computer Science and Engineering, University of California, San Diego, CA, USA
| | - Rob Knight
- Department of Pediatrics, University of California, San Diego, CA, USA
- Department of Computer Science and Engineering, University of California, San Diego, CA, USA
| | - Bruce W Patterson
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA.
- Sansum Diabetes Research Institute, Santa Barbara, CA, USA.
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Schweitzer GG, Beckner DC, Smith GI, Klein S. Short-term Intensive Lifestyle Therapy in a Worksite Setting Improves Cardiometabolic Health in People With Obesity. J Endocr Soc 2023; 7:bvad048. [PMID: 37153109 PMCID: PMC10161138 DOI: 10.1210/jendso/bvad048] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Indexed: 05/09/2023] Open
Abstract
Context The Pritikin Program, which provides intensive lifestyle therapy, has been shown to improve cardiometabolic outcomes when provided as a residential program. Objective The purpose of the present study was to conduct a short-term, randomized, controlled trial to evaluate the feasibility and clinical efficacy of treatment with the Pritikin Program in an outpatient worksite setting. Methods Cardiometabolic outcomes were evaluated in people with overweight/obesity and ≥2 metabolic abnormalities (high triglycerides, low high-density lipoprotein (HDL) cholesterol, high blood pressure, HbA1c > 5.7%), before and after they were randomized to 6 weeks of standard care (n = 26) or intensive lifestyle therapy, based on the Pritikin Program (n = 28). Participants in the lifestyle intervention group were provided all food as packed-out meals and participated in group nutrition, behavioral education, cooking classes, and exercise sessions 3 times per week at a worksite location. Results Compared with standard care, intensive lifestyle therapy decreased body weight (-5.0% vs -0.5%), HbA1c (-15.5% vs +2.3%), plasma total cholesterol (-9.8% vs +7.7%), low-density lipoprotein cholesterol (-10.3% vs +9.3%) and triglyceride (-21.7% vs +3.0%) concentrations, and systolic blood pressure (-7.0% vs 0%) (all P values < .02), and increased exercise tolerance (time to exhaustion walking on a treadmill by +23.7% vs +4.5%; P < .001). Conclusion This study demonstrates the feasibility and clinical effectiveness of short-term, intensive outpatient lifestyle therapy in people with overweight/obesity and increased risk of coronary heart disease when all food is provided and the intervention is conducted at a convenient worksite setting.
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Affiliation(s)
- George G Schweitzer
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Gordon I Smith
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA
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Farabi SS, Smith GI, Schweitzer GG, Stein RI, Klein S. Do lifestyle factors and quality of life differ in people with metabolically healthy and unhealthy obesity? Int J Obes (Lond) 2022; 46:1778-1785. [PMID: 35817849 PMCID: PMC9996800 DOI: 10.1038/s41366-022-01180-6] [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] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 06/17/2022] [Accepted: 06/27/2022] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND OBJECTIVES Although obesity is typically associated with metabolic co-morbidities, some people with obesity do not develop metabolic abnormalities. We evaluated whether modifiable lifestyle factors (i.e., physical activity, dietary composition, and sleep characteristics) can help explain why some people with obesity are metabolically healthy (MHO) and whether metabolically unhealthy obesity (MUO) affects quality of life (QOL). SUBJECTS/METHODS Physical activity and sleep characteristics were assessed by using tri-axial accelerometers and dietary intake, sleep quality, and QOL were evaluated by using validated questionnaires in people stratified into three groups: (1) lean with normal glucose tolerance, plasma triglyceride (TG) concentration and intrahepatic TG (IHTG) content (metabolically healthy lean [MHL]; n = 20); (2) obesity and normal glucose tolerance, plasma TG concentration and IHTG content (MHO; n = 36); and (3) obesity with abnormal glucose metabolism and hepatic steatosis (MUO; n = 43). RESULTS People with MHO performed ~45-min more light-intensity physical activity/day than the MHL and MUO groups (P < 0.05). QOL, particularly the physical function domain, was higher in the MHO than the MUO group (P < 0.05). Although self-reported intake of starch, dairy, and cured meats were higher in the MUO than the MHO group (P < 0.02), the absolute differences were small and unlikely to have metabolic effects. No differences were found in sleep duration or quality between groups. CONCLUSIONS These data suggest physical activity, but not sleep or dietary intake, contribute to better metabolic health in people with MHO than those with MUO, and that QOL is lower in people with MUO than those with MHO.
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Affiliation(s)
- Sarah S Farabi
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
- Goldfarb School of Nursing at Barnes-Jewish College, St. Louis, MO, USA
| | - Gordon I Smith
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - George G Schweitzer
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - Richard I Stein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA.
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Beals JW, Smith GI, Shankaran M, Fuchs A, Schweitzer GG, Yoshino J, Field T, Matthews M, Nyangau E, Morozov D, Mittendorfer B, Hellerstein MK, Klein S. Increased Adipose Tissue Fibrogenesis, Not Impaired Expandability, Is Associated With Nonalcoholic Fatty Liver Disease. Hepatology 2021; 74:1287-1299. [PMID: 33743554 PMCID: PMC8559258 DOI: 10.1002/hep.31822] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/07/2021] [Accepted: 03/14/2021] [Indexed: 12/27/2022]
Abstract
BACKGROUND AND AIMS It is proposed that impaired expansion of subcutaneous adipose tissue (SAT) and an increase in adipose tissue (AT) fibrosis causes ectopic lipid accumulation, insulin resistance (IR), and metabolically unhealthy obesity. We therefore evaluated whether a decrease in SAT expandability, assessed by measuring SAT lipogenesis (triglyceride [TG] production), and an increase in SAT fibrogenesis (collagen production) are associated with NAFLD and IR in persons with obesity. APPROACH AND RESULTS In vivo abdominal SAT lipogenesis and fibrogenesis, expression of SAT genes involved in extracellular matrix (ECM) formation, and insulin sensitivity were assessed in three groups of participants stratified by adiposity and intrahepatic TG (IHTG) content: (1) healthy lean with normal IHTG content (Lean-NL; n = 12); (2) obese with normal IHTG content and normal glucose tolerance (Ob-NL; n = 25); and (3) obese with NAFLD and abnormal glucose metabolism (Ob-NAFLD; n = 25). Abdominal SAT TG synthesis rates were greater (P < 0.05) in both the Ob-NL (65.9 ± 4.6 g/wk) and Ob-NAFLD groups (71.1 ± 6.7 g/wk) than the Lean-NL group (16.2 ± 2.8 g/wk) without a difference between the Ob-NL and Ob-NAFLD groups. Abdominal SAT collagen synthesis rate and the composite expression of genes encoding collagens progressively increased from the Lean-NL to the Ob-NL to the Ob-NAFLD groups and were greater in the Ob-NAFLD than the Ob-NL group (P < 0.05). Composite expression of collagen genes was inversely correlated with both hepatic and whole-body insulin sensitivity (P < 0.001). CONCLUSIONS AT expandability is not impaired in persons with obesity and NAFLD. However, SAT fibrogenesis is greater in persons with obesity and NAFLD than in those with obesity and normal IHTG content, and is inversely correlated with both hepatic and whole-body insulin sensitivity.
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Affiliation(s)
- Joseph W. Beals
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St Louis, MO
| | - Gordon I. Smith
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St Louis, MO
| | | | - Anja Fuchs
- Department of Surgery, Washington University School of Medicine, St Louis, MO
| | - George G. Schweitzer
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St Louis, MO
| | - Jun Yoshino
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St Louis, MO
| | - Tyler Field
- University of California Berkeley, Berkeley, CA
| | | | | | - Darya Morozov
- Department of Radiology, Washington University School of Medicine, St Louis, MO
| | - Bettina Mittendorfer
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St Louis, MO
| | | | - Samuel Klein
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St Louis, MO
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Chambers KT, Cooper MA, Swearingen AR, Brookheart RT, Schweitzer GG, Weinheimer CJ, Kovacs A, Koves TR, Muoio DM, McCommis KS, Finck BN. Myocardial Lipin 1 knockout in mice approximates cardiac effects of human LPIN1 mutations. JCI Insight 2021; 6:134340. [PMID: 33986192 PMCID: PMC8262319 DOI: 10.1172/jci.insight.134340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/31/2021] [Indexed: 11/17/2022] Open
Abstract
Lipin 1 is a bifunctional protein that is a transcriptional regulator and has phosphatidic acid (PA) phosphohydrolase activity, which dephosphorylates PA to generate diacylglycerol. Human lipin 1 mutations lead to episodic rhabdomyolysis, and some affected patients exhibit cardiac abnormalities, including exercise-induced cardiac dysfunction and cardiac triglyceride accumulation. Furthermore, lipin 1 expression is deactivated in failing heart, but the effects of lipin 1 deactivation in myocardium are incompletely understood. We generated mice with cardiac-specific lipin 1 KO (cs-Lpin1-/-) to examine the intrinsic effects of lipin 1 in the myocardium. Cs-Lpin1-/- mice had normal systolic cardiac function but mild cardiac hypertrophy. Compared with littermate control mice, PA content was higher in cs-Lpin1-/- hearts, which also had an unexpected increase in diacylglycerol and triglyceride content. Cs-Lpin1-/- mice exhibited diminished cardiac cardiolipin content and impaired mitochondrial respiration rates when provided with pyruvate or succinate as metabolic substrates. After transverse aortic constriction-induced pressure overload, loss of lipin 1 did not exacerbate cardiac hypertrophy or dysfunction. However, loss of lipin 1 dampened the cardiac ionotropic response to dobutamine and exercise endurance in association with reduced protein kinase A signaling. These data suggest that loss of lipin 1 impairs cardiac functional reserve, likely due to effects on glycerolipid homeostasis, mitochondrial function, and protein kinase A signaling.
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Affiliation(s)
- Kari T Chambers
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael A Cooper
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alison R Swearingen
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Rita T Brookheart
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - George G Schweitzer
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Carla J Weinheimer
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Attila Kovacs
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Timothy R Koves
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Departments of Medicine and Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Deborah M Muoio
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Departments of Medicine and Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA
| | - Kyle S McCommis
- Department of Biochemistry & Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Brian N Finck
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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Barenie MJ, Domenick JT, Bennett JE, Schweitzer GG, Shetty P, Weiss EP. Short Term High-Repetition Back Squat Protocol Does Not Improve 5-km Run Performance. Int J Exerc Sci 2020; 13:1770-1782. [PMID: 33414887 PMCID: PMC7745891] [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] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The purpose of this study was to evaluate the hypothesis that a novel high-repetition, low-resistance back squat training protocol, designed to stimulate high-intensity interval training, improves 5-km run performance. Fifteen runners [4 male, 11 female; 150 + minutes of endurance exercise/week; age = 22.7 ± 2.0 y; 21.5 ± 2.2 kg/m2 BMI] in this single-group test-retest design completed two weeks of back squats consisting of three sets of 15-24 repetitions at 60% of estimated one-repetition max (1RM), three times per week (1-2 days of rest between sessions). Outcome tests included a 5-km outdoor timed run, laboratory indirect calorimetry to quantify substrate oxidation rates during steady-state submaximal exercise (60% and 70% heart rate max (HRmax)), and estimated 1RM for back squats. Back squat estimated 1RM increased by 20% (58.3 ± 18.5 to 70.2 ± 16.7 kg, P < 0.001). However, 5-km run times due to the back squat protocol did not significantly change (Pre-Squats: 23.9 ± 5.0 vs. Post-Squats: 23.7 ± 4.3 minutes, P = 0.71). Likewise, the squat training program did not significantly alter carbohydrate or lipid oxidation rates during steady-state submaximal exercise at 60% or 70% of HRmax (P values ranged from 0.36 - 0.99). Short term high-repetition back squat training does not appear to impact 5-km run performance or substrate utilization during submaximal exercise.
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Affiliation(s)
- Matthew J Barenie
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA
- Human Performance and Exercise Biochemistry Laboratory, Department of Kinesiology, Indiana University, Bloomington, IN, USA
| | - Jordan T Domenick
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA
| | - Jason E Bennett
- Department of Physical Therapy, Carroll University, Waukesha, WI, USA
| | - George G Schweitzer
- Deparment of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Paulina Shetty
- Science Department, Johnson County Community College, Overland Park, KS, USA
| | - Edward P Weiss
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA
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Smith GI, Shankaran M, Yoshino M, Schweitzer GG, Chondronikola M, Beals JW, Okunade AL, Patterson BW, Nyangau E, Field T, Sirlin CB, Talukdar S, Hellerstein MK, Klein S. Insulin resistance drives hepatic de novo lipogenesis in nonalcoholic fatty liver disease. J Clin Invest 2020; 130:1453-1460. [PMID: 31805015 DOI: 10.1172/jci134165] [Citation(s) in RCA: 335] [Impact Index Per Article: 83.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 11/20/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUNDAn increase in intrahepatic triglyceride (IHTG) is the hallmark feature of nonalcoholic fatty liver disease (NAFLD) and is decreased by weight loss. Hepatic de novo lipogenesis (DNL) contributes to steatosis in individuals with NAFLD. The physiological factors that stimulate hepatic DNL and the effect of weight loss on hepatic DNL are not clear.METHODSHepatic DNL, 24-hour integrated plasma insulin and glucose concentrations, and both liver and whole-body insulin sensitivity were determined in individuals who were lean (n = 14), obese with normal IHTG content (n = 26), or obese with NAFLD (n = 27). Hepatic DNL was assessed using the deuterated water method corrected for the potential confounding contribution of adipose tissue DNL. Liver and whole-body insulin sensitivity was assessed using the hyperinsulinemic-euglycemic clamp procedure in conjunction with glucose tracer infusion. Six subjects in the obese-NAFLD group were also evaluated before and after a diet-induced weight loss of 10%.RESULTSThe contribution of hepatic DNL to IHTG-palmitate was 11%, 19%, and 38% in the lean, obese, and obese-NAFLD groups, respectively. Hepatic DNL was inversely correlated with hepatic and whole-body insulin sensitivity, but directly correlated with 24-hour plasma glucose and insulin concentrations. Weight loss decreased IHTG content, in conjunction with a decrease in hepatic DNL and 24-hour plasma glucose and insulin concentrations.CONCLUSIONSThese data suggest hepatic DNL is an important regulator of IHTG content and that increases in circulating glucose and insulin stimulate hepatic DNL in individuals with NAFLD. Weight loss decreased IHTG content, at least in part, by decreasing hepatic DNL.TRIAL REGISTRATIONClinicalTrials.gov NCT02706262.FUNDINGThis study was supported by NIH grants DK56341 (Nutrition Obesity Research Center), DK20579 (Diabetes Research Center), DK52574 (Digestive Disease Research Center), and RR024992 (Clinical and Translational Science Award), and by grants from the Academy of Nutrition and Dietetics Foundation, the College of Natural Resources of UCB, and the Pershing Square Foundation.
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Affiliation(s)
- Gordon I Smith
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Mahalakshmi Shankaran
- Department of Nutritional Sciences and Toxicology, College of Natural Resources, University of California at Berkeley, Berkeley, California, USA
| | - Mihoko Yoshino
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - George G Schweitzer
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Maria Chondronikola
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Joseph W Beals
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Adewole L Okunade
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Bruce W Patterson
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Edna Nyangau
- Department of Nutritional Sciences and Toxicology, College of Natural Resources, University of California at Berkeley, Berkeley, California, USA
| | - Tyler Field
- Department of Nutritional Sciences and Toxicology, College of Natural Resources, University of California at Berkeley, Berkeley, California, USA
| | - Claude B Sirlin
- Liver Imaging Group, University of California, San Diego, La Jolla, California, USA
| | | | - Marc K Hellerstein
- Department of Nutritional Sciences and Toxicology, College of Natural Resources, University of California at Berkeley, Berkeley, California, USA
| | - Samuel Klein
- Atkins Center of Excellence in Obesity Medicine, Center for Human Nutrition, John T. Milliken Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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Schweitzer GG, Gan C, Bucelli RC, Wegner D, Schmidt RE, Shinawi M, Finck BN, Brookheart RT. A mutation in Site-1 Protease is associated with a complex phenotype that includes episodic hyperCKemia and focal myoedema. Mol Genet Genomic Med 2019; 7:e00733. [PMID: 31070020 PMCID: PMC6625134 DOI: 10.1002/mgg3.733] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [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: 08/20/2018] [Revised: 01/25/2019] [Accepted: 04/04/2019] [Indexed: 01/04/2023] Open
Abstract
Background Site‐1 Protease (S1P) is a Golgi‐resident protein required for the activation of regulatory proteins that drive key cellular functions, including, the unfolded protein response (UPR) and lipid and cholesterol biosynthesis. While disruptions in S1P function have been widely characterized in animal models, to date, the implications of disrupted S1P function in human disease states are not completely known. Methods The patient and both parents underwent whole exome and mitochondrial DNA sequencing, and Sanger sequencing was used to confirm the mutation. Western blotting and immunofluorescence studies were performed on either proband‐derived fibroblasts or on an established cell line to assess protein expression and cellular localization of the mutated S1P protein. Quantitative real‐time PCR and luciferase reporter assays were used to examine activation of S1P target pathways in the context of the S1P mutation. Results We describe a female patient with a de novo heterozygous missense mutation in the transmembrane domain of S1P (p. Pro1003Ser). The patient presented to our neuromuscular clinic with episodic, activity‐induced, focal myoedema and myalgias with hyperCKemia. Her clinical phenotype was complex and included gastrointestinal hypomotility, ocular migraines, and polycystic ovary syndrome. Molecular analysis using proband‐derived fibroblasts and cell lines harboring the Pro1003Ser mutation demonstrated increased activation of UPR and lipid and cholesterol regulatory pathways and localization of S1P Pro1003Ser in the Golgi. Conclusion These findings suggest a critical function for S1P in several human organ systems and implicate an important role for S1P in various human disease states.
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Affiliation(s)
- George G Schweitzer
- John T. Milliken Department of Medicine, Division of Geriatrics and Nutritional Sciences, Washington University School of Medicine, St. Louis, Missouri
| | - Connie Gan
- John T. Milliken Department of Medicine, Division of Geriatrics and Nutritional Sciences, Washington University School of Medicine, St. Louis, Missouri
| | - Robert C Bucelli
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Daniel Wegner
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Robert E Schmidt
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri
| | - Marwan Shinawi
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.,Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Brian N Finck
- John T. Milliken Department of Medicine, Division of Geriatrics and Nutritional Sciences, Washington University School of Medicine, St. Louis, Missouri
| | - Rita T Brookheart
- John T. Milliken Department of Medicine, Division of Geriatrics and Nutritional Sciences, Washington University School of Medicine, St. Louis, Missouri
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10
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Cade WT, Bohnert KL, Peterson LR, Patterson BW, Bittel AJ, Okunade AL, de las Fuentes L, Steger-May K, Bashir A, Schweitzer GG, Chacko SK, Wanders RJ, Pacak CA, Byrne BJ, Reeds DN. Blunted fat oxidation upon submaximal exercise is partially compensated by enhanced glucose metabolism in children, adolescents, and young adults with Barth syndrome. J Inherit Metab Dis 2019; 42:480-493. [PMID: 30924938 PMCID: PMC6483838 DOI: 10.1002/jimd.12094] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 03/27/2019] [Indexed: 12/26/2022]
Abstract
Barth syndrome (BTHS) is a rare X-linked condition resulting in abnormal mitochondria, cardioskeletal myopathy, and growth delay; however, the effects of BTHS on substrate metabolism regulation and their relationships with tissue function in humans are unknown. We sought to characterize glucose and fat metabolism during rest, submaximal exercise, and postexercise rest in children, adolescents, and young adults with BTHS and unaffected controls and examine their relationships with cardioskeletal energetics and function. Children/adolescents and young adults with BTHS (n = 29) and children/adolescent and young adult control participants (n = 28, total n = 57) underwent an infusion of 6'6'H2 glucose and U-13 C palmitate and indirect calorimetry during rest, 30-minutes of moderate exercise (50% V˙O2peak ), and recovery. Cardiac function, cardioskeletal mitochondrial energetics, and exercise capacity were examined via echocardiography, 31 P magnetic resonance spectroscopy, and peak exercise testing, respectively. The glucose turnover rate was significantly higher in individuals with BTHS during rest (33.2 ± 9.8 vs 27.2 ± 8.1 μmol/kgFFM/min, P < .01) and exercise (34.7 ± 11.2 vs 29.5 ± 8.8 μmol/kgFFM/min, P < .05) and tended to be higher postexercise (33.7 ± 10.2 vs 28.8 ± 8.0 μmol/kgFFM/min, P < .06) compared to controls. Increases in total fat (-3.9 ± 7.5 vs 10.5 ± 8.4 μmol/kgFFM/min, P < .0001) and plasma fatty acid oxidation rates (0.0 ± 1.8 vs 5.1 ± 3.9 μmol/kgFFM/min, P < .0001) from rest to exercise were severely blunted in BTHS compared to controls. Conclusion: An inability to upregulate fat metabolism during moderate intensity exercise appears to be partially compensated by elevations in glucose metabolism. Derangements in fat and glucose metabolism are characteristic of the pathophysiology of BTHS. A severely blunted ability to upregulate fat metabolism during a modest level of physical activity is a defining pathophysiologic characteristic in children, adolescents, and young adults with BTHS.
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Affiliation(s)
- W. Todd Cade
- Program in Physical Therapy, 4444 Forest Park Avenue, Washington University School of Medicine, St. Louis, MO
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Kathryn L. Bohnert
- Program in Physical Therapy, 4444 Forest Park Avenue, Washington University School of Medicine, St. Louis, MO
| | - Linda R. Peterson
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Bruce W. Patterson
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Adam J. Bittel
- Program in Physical Therapy, 4444 Forest Park Avenue, Washington University School of Medicine, St. Louis, MO
| | - Adewole L. Okunade
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Lisa de las Fuentes
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Karen Steger-May
- Division of Biostatistics, Washington University School of Medicine, St. Louis, MO
| | - Adil Bashir
- Department of Radiology, Washington University School of Medicine, St. Louis, MO
- Department of Electrical and Computer Engineering, Auburn University, Auburn, AL
| | | | - Shaji K. Chacko
- Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Ronald J. Wanders
- Department of Pediatrics, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Barry J Byrne
- Department of Pediatrics, University of Florida, Gainesville, FL
| | - Dominic N. Reeds
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
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11
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Lutkewitte AJ, McCommis KS, Schweitzer GG, Chambers KT, Graham MJ, Wang L, Patti GJ, Hall AM, Finck BN. Hepatic monoacylglycerol acyltransferase 1 is induced by prolonged food deprivation to modulate the hepatic fasting response. J Lipid Res 2019; 60:528-538. [PMID: 30610082 PMCID: PMC6399500 DOI: 10.1194/jlr.m089722] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 09/04/2018] [Revised: 12/05/2018] [Indexed: 01/14/2023] Open
Abstract
During prolonged fasting, the liver plays a central role in maintaining systemic energy homeostasis by producing glucose and ketones in processes fueled by oxidation of fatty acids liberated from adipose tissue. In mice, this is accompanied by transient hepatic accumulation of glycerolipids. We found that the hepatic expression of monoacylglycerol acyltransferase 1 (Mogat1), an enzyme with monoacylglycerol acyltransferase (MGAT) activity that produces diacyl-glycerol from monoacylglycerol, was significantly increased in the liver of fasted mice compared with mice given ad libitum access to food. Basal and fasting-induced expression of Mogat1 was markedly diminished in the liver of mice lacking the transcription factor PPARα. Suppressing Mogat1 expression in liver and adipose tissue with antisense oligonucleotides (ASOs) reduced hepatic MGAT activity and triglyceride content compared with fasted controls. Surprisingly, the expression of many other PPARα target genes and PPARα activity was also decreased in mice given Mogat1 ASOs. When mice treated with control or Mogat1 ASOs were gavaged with the PPARα ligand, WY-14643, and then fasted for 18 h, WY-14643 administration reversed the effects of Mogat1 ASOs on PPARα target gene expression and liver triglyceride content. In conclusion, Mogat1 is a fasting-induced PPARα target gene that may feed forward to regulate liver PPARα activity during food deprivation.
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Affiliation(s)
- Andrew J Lutkewitte
- Center for Human Nutrition Washington University School of Medicine, St. Louis, MO
| | - Kyle S McCommis
- Center for Human Nutrition Washington University School of Medicine, St. Louis, MO
| | - George G Schweitzer
- Center for Human Nutrition Washington University School of Medicine, St. Louis, MO
| | - Kari T Chambers
- Center for Human Nutrition Washington University School of Medicine, St. Louis, MO
| | | | - Lingjue Wang
- Department of Chemistry, Washington University, St. Louis, MO
| | - Gary J Patti
- Department of Chemistry, Washington University, St. Louis, MO
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Angela M Hall
- Center for Human Nutrition Washington University School of Medicine, St. Louis, MO
| | - Brian N Finck
- Center for Human Nutrition Washington University School of Medicine, St. Louis, MO
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12
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Schweitzer GG, Collier SL, Chen Z, McCommis KS, Pittman SK, Yoshino J, Matkovich SJ, Hsu FF, Chrast R, Eaton JM, Harris TE, Weihl CC, Finck BN. Loss of lipin 1-mediated phosphatidic acid phosphohydrolase activity in muscle leads to skeletal myopathy in mice. FASEB J 2018; 33:652-667. [PMID: 30028636 DOI: 10.1096/fj.201800361r] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [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: 12/25/2022]
Abstract
Lipin 1 regulates glycerolipid homeostasis by acting as a phosphatidic acid phosphohydrolase (PAP) enzyme in the triglyceride-synthesis pathway and by regulating transcription factor activity. Mutations in human lipin 1 are a common cause of recurrent rhabdomyolysis in children. Mice with constitutive whole-body lipin 1 deficiency have been used to examine mechanisms connecting lipin 1 deficiency to myocyte injury. However, that mouse model is confounded by lipodystrophy not phenocopied in people. Herein, 2 muscle-specific mouse models were studied: 1) Lpin1 exon 3 and 4 deletion, resulting in a hypomorphic protein without PAP activity, but which preserved transcriptional coregulatory function; and 2) Lpin1 exon 7 deletion, resulting in total protein loss. In both models, skeletal muscles exhibited a chronic myopathy with ongoing muscle fiber necrosis and regeneration and accumulation of phosphatidic acid and, paradoxically, diacylglycerol. Additionally, lipin 1-deficient mice had abundant, but abnormal, mitochondria likely because of impaired autophagy. Finally, these mice exhibited increased plasma creatine kinase following exhaustive exercise when unfed. These data suggest that mice lacking lipin 1-mediated PAP activity in skeletal muscle may serve as a model for determining the mechanisms by which lipin 1 deficiency leads to myocyte injury and for testing potential therapeutic approaches.-Schweitzer, G. G., Collier, S. L., Chen, Z., McCommis, K. S., Pittman, S. K., Yoshino, J., Matkovich, S. J., Hsu, F.-F., Chrast, R., Eaton, J. M., Harris, T. E., Weihl, C. C., Finck, B. N. Loss of lipin 1-mediated phosphatidic acid phosphohydrolase activity in muscle leads to skeletal myopathy in mice.
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Affiliation(s)
- George G Schweitzer
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sara L Collier
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Zhouji Chen
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kyle S McCommis
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sara K Pittman
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jun Yoshino
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Scot J Matkovich
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Fong-Fu Hsu
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Roman Chrast
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden; and.,Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; and
| | - James M Eaton
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Conrad C Weihl
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Brian N Finck
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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13
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Liss KH, McCommis KS, Chambers KT, Pietka TA, Schweitzer GG, Park SL, Nalbantoglu ILK, Weinheimer CJ, Hall AM, Finck BN. The impact of diet-induced hepatic steatosis in a murine model of hepatic ischemia/reperfusion injury. Liver Transpl 2018; 24:908-921. [PMID: 29729104 PMCID: PMC6097916 DOI: 10.1002/lt.25189] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 11/22/2017] [Accepted: 04/18/2018] [Indexed: 12/21/2022]
Abstract
The prevalence of obesity-associated nonalcoholic fatty liver disease has significantly increased over the past decade, and end-stage liver disease secondary to nonalcoholic steatohepatitis has become 1 of the most common indications for liver transplantation. This both increases the demand for organs and decreases the availability of donor livers deemed suitable for transplantation. Although in the past many steatotic livers were discarded due to concerns over enhanced susceptibility to ischemia/reperfusion injury (IRI) and organ failure, the discrepancy between supply and demand has resulted in increasing use of expanded criteria donor organs including steatotic livers. However, it remains controversial whether steatotic livers can be safely used for transplantation and how best to improve the performance of steatotic grafts. We aimed to evaluate the impact of diet-induced hepatic steatosis in a murine model of IRI. Using a diet of high trans-fat, fructose, and cholesterol (HTF-C) and a diet high in saturated fats, sucrose, and cholesterol (Western diet), we were able to establish models of mixed macrovesicular and microvesicular steatosis (HTF-C) and microvesicular steatosis (Western). We found that the presence of hepatic steatosis, whether it is predominantly macrovesicular or microvesicular, significantly worsens IRI as measured by plasma alanine aminotransferase levels and inflammatory cytokine concentration, and histological evaluation for necrosis. Additionally, we report on a novel finding in which hepatic IRI in the setting of steatosis results in the induction of the necroptosis factors, receptor interacting protein kinase (RIPK) 3, RIPK1, and mixed-lineage kinase domain-like. These data lay the groundwork for additional experimentation to test potential therapeutic approaches to limit IRI in steatotic livers by using a genetically tractable system. Liver Transplantation 24 908-921 2018 AASLD.
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Affiliation(s)
- Kim H.H. Liss
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO
| | - Kyle S. McCommis
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Kari T. Chambers
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Terri A. Pietka
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | | | - Sara L. Park
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - ILKe Nalbantoglu
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Carla J. Weinheimer
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Angela M. Hall
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Brian N. Finck
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
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14
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Wroble KA, Trott MN, Schweitzer GG, Rahman RS, Kelly PV, Weiss EP. Low-carbohydrate, ketogenic diet impairs anaerobic exercise performance in exercise-trained women and men: a randomized-sequence crossover trial. J Sports Med Phys Fitness 2018; 59:600-607. [PMID: 29619799 DOI: 10.23736/s0022-4707.18.08318-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Low-carbohydrate, ketogenic diets cause mild, subclinical systemic acidosis. Anaerobic exercise performance is limited by acidosis. Therefore, we evaluated the hypothesis that a low-carbohydrate, ketogenic diet impairs anaerobic exercise performance, as compared to a high-carbohydrate diet. METHODS Sixteen men and women (BMI, 23±1 kg/m2, age 23±1 years) participated in a randomized-sequence, counterbalanced crossover study in which they underwent exercise testing after 4 days of either a low-carbohydrate, ketogenic diet (LC; <50 g/day and <10% of energy from carbohydrates) or a high-carbohydrate diet (HC; 6-10 g/kg/day carbohydrate). Dietary compliance was assessed with nutrient analysis of diet records, and with measures of urine pH and ketones. Anaerobic exercise performance was evaluated with the Wingate anaerobic cycling test and the yo-yo intermittent recovery test. RESULTS The diets were matched for total energy (LC: 2333±158 kcal/d; HC: 2280±160 kcal/d; P=0.65) but differed in carbohydrate content (9±1% vs. 63±2% of energy intake; P<0.001). LC resulted in lower urine pH (5.9±0.1 vs. 6.3±0.2, P=0.004) and the appearance of urine ketones in every participant. LC resulted in 7% lower peak power (801±58 watts vs. 857±61 watts, P=0.008) and 6% lower mean power (564±50 watts vs. 598±51 watts, P=0.01) during the Wingate Test. Total distance ran in the yo-yo intermittent recovery test was 15% less after LC diet (887±139 vs. 1045±145 meters, P=0.02). CONCLUSIONS Short-term low-carbohydrate, ketogenic diets reduce exercise performance in activities that are heavily dependent on anaerobic energy systems. These findings have clear performance implications for athletes, especially for high-intensity, short duration activities and sports.
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Affiliation(s)
- Kymberly A Wroble
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA
| | - Morgan N Trott
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA
| | - George G Schweitzer
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA.,Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO, USA
| | - Rabia S Rahman
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA
| | - Patrick V Kelly
- Doisy College of Health Sciences, Saint Louis University, St. Louis, MO, USA
| | - Edward P Weiss
- Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO, USA - .,Doisy College of Health Sciences, Saint Louis University, St. Louis, MO, USA
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15
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Lutkewitte AJ, Schweitzer GG, Kennon-McGill S, Clemens MM, James LP, Jaeschke H, Finck BN, McGill MR. Lipin deactivation after acetaminophen overdose causes phosphatidic acid accumulation in liver and plasma in mice and humans and enhances liver regeneration. Food Chem Toxicol 2018. [PMID: 29534981 DOI: 10.1016/j.fct.2018.03.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Andrew J Lutkewitte
- Div. of Geriatrics and Nutritional Sciences, Dept. of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - George G Schweitzer
- Div. of Geriatrics and Nutritional Sciences, Dept. of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - Stefanie Kennon-McGill
- Dept. of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Melissa M Clemens
- Interdisciplinary Biomedical Sciences Graduate Program, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Laura P James
- Dept. of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Hartmut Jaeschke
- Dept. of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA.
| | - Brian N Finck
- Div. of Geriatrics and Nutritional Sciences, Dept. of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - Mitchell R McGill
- Dept. of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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16
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Affiliation(s)
- George G Schweitzer
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
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17
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Vigueira PA, McCommis KS, Hodges WT, Schweitzer GG, Cole SL, Oonthonpan L, Taylor EB, McDonald WG, Kletzien RF, Colca JR, Finck BN. The beneficial metabolic effects of insulin sensitizers are not attenuated by mitochondrial pyruvate carrier 2 hypomorphism. Exp Physiol 2017; 102:985-999. [PMID: 28597936 DOI: 10.1113/ep086380] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [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: 03/29/2017] [Accepted: 06/06/2017] [Indexed: 12/24/2022]
Abstract
NEW FINDINGS What is the central question of this study? The antidiabetic effects of thiazolidinedione (TZD) drugs may be mediated in part by a molecular interaction with the constituent proteins of the mitochondrial pyruvate carrier complex (MPC1 and MPC2). We examined the ability of a mutant mouse strain expressing an N-terminal truncation of MPC2 (Mpc2Δ16 mice) to respond to TZD treatment. What is the main finding and its importance? The response of Mpc2Δ16 mice to TZD treatment was not significantly different from that of wild-type C57BL6/J control animals, suggesting that the 16 N-terminal amino acids of MPC2 are dispensable for the effects of TZD treatment. Rosiglitazone and pioglitazone are thiazolidinedione (TZD) compounds that have been used clinically as insulin-sensitizing drugs and are generally believed to mediate their effects via activation of the peroxisome proliferator-activated receptor γ (PPARγ). Recent work has shown that it is possible to synthesize TZD compounds with potent insulin-sensitizing effects and markedly diminished affinity for PPARγ. Both clinically used TZDs and investigational PPARγ-sparing TZDs, such as MSDC-0602, interact with the mitochondrial pyruvate carrier (MPC) and inhibit its activity. The MPC complex is composed of two proteins, MPC1 and MPC2. Herein, we used mice expressing a hypomorphic MPC2 protein missing 16 amino acids in the N-terminus (Mpc2Δ16 mice) to determine the effects of these residues in mediating the insulin-sensitizing effects of TZDs in diet-induced obese mice. We found that both pioglitazone and MSDC-0602 elicited their beneficial metabolic effects, including improvement in glucose tolerance, attenuation of hepatic steatosis, reduction of adipose tissue inflammation and stimulation of adipocyte browning, in both wild-type and Mpc2Δ16 mice after high-fat diet feeding. In addition, truncation of MPC2 failed to attenuate the interaction between TZDs and the MPC in a bioluminescence resonance energy transfer-based assay or to affect the suppression of pyruvate-stimulated respiration in cells. Collectively, these data suggest that the interaction between TZDs and MPC2 is not affected by loss of the N-terminal 16 amino acids nor are these residues required for the insulin-sensitizing effects of these compounds.
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Affiliation(s)
- Patrick A Vigueira
- Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Kyle S McCommis
- Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Wesley T Hodges
- Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - George G Schweitzer
- Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Serena L Cole
- Metabolic Solutions Development Company, Kalamazoo, MI, 49007, USA
| | - Lalita Oonthonpan
- Department of Biochemistry and Fraternal Order of the Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, IA, 52240, USA
| | - Eric B Taylor
- Department of Biochemistry and Fraternal Order of the Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, IA, 52240, USA
| | | | - Rolf F Kletzien
- Metabolic Solutions Development Company, Kalamazoo, MI, 49007, USA
| | - Jerry R Colca
- Metabolic Solutions Development Company, Kalamazoo, MI, 49007, USA
| | - Brian N Finck
- Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
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18
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Affiliation(s)
- George G Schweitzer
- Centre for Human Nutrition and Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Monica L Kearney
- Centre for Human Nutrition and Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Bettina Mittendorfer
- Centre for Human Nutrition and Department of Medicine, Washington University School of Medicine, St Louis, MO, 63110, USA
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19
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Schweitzer GG, Chen Z, Gan C, McCommis KS, Soufi N, Chrast R, Mitra MS, Yang K, Gross RW, Finck BN. Liver-specific loss of lipin-1-mediated phosphatidic acid phosphatase activity does not mitigate intrahepatic TG accumulation in mice. J Lipid Res 2015; 56:848-58. [PMID: 25722343 DOI: 10.1194/jlr.m055962] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lipin proteins (lipin 1, 2, and 3) regulate glycerolipid homeostasis by acting as phosphatidic acid phosphohydrolase (PAP) enzymes in the TG synthesis pathway and by regulating DNA-bound transcription factors to control gene transcription. Hepatic PAP activity could contribute to hepatic fat accumulation in response to physiological and pathophysiological stimuli. To examine the role of lipin 1 in regulating hepatic lipid metabolism, we generated mice that are deficient in lipin-1-encoded PAP activity in a liver-specific manner (Alb-Lpin1(-/-) mice). This allele of lipin 1 was still able to transcriptionally regulate the expression of its target genes encoding fatty acid oxidation enzymes, and the expression of these genes was not affected in Alb-Lpin1(-/-) mouse liver. Hepatic PAP activity was significantly reduced in mice with liver-specific lipin 1 deficiency. However, hepatocytes from Alb-Lpin1(-/-) mice had normal rates of TG synthesis, and steady-state hepatic TG levels were unaffected under fed and fasted conditions. Furthermore, Alb-Lpin1(-/-) mice were not protected from intrahepatic accumulation of diacylglycerol and TG after chronic feeding of a diet rich in fat and fructose. Collectively, these data demonstrate that marked deficits in hepatic PAP activity do not impair TG synthesis and accumulation under acute or chronic conditions of lipid overload.
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Affiliation(s)
| | - Zhouji Chen
- Washington University School of Medicine, St. Louis, MO 63110
| | - Connie Gan
- Washington University School of Medicine, St. Louis, MO 63110
| | - Kyle S McCommis
- Washington University School of Medicine, St. Louis, MO 63110
| | - Nisreen Soufi
- Washington University School of Medicine, St. Louis, MO 63110
| | - Roman Chrast
- Department of Medical Genetics, University of Lausanne, 1005 Lausanne, Switzerland
| | | | - Kui Yang
- Washington University School of Medicine, St. Louis, MO 63110
| | - Richard W Gross
- Washington University School of Medicine, St. Louis, MO 63110
| | - Brian N Finck
- Washington University School of Medicine, St. Louis, MO 63110
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20
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Devanathan S, Whitehead T, Schweitzer GG, Fettig N, Kovacs A, Korach KS, Finck BN, Shoghi KI. An animal model with a cardiomyocyte-specific deletion of estrogen receptor alpha: functional, metabolic, and differential network analysis. PLoS One 2014; 9:e101900. [PMID: 25000186 PMCID: PMC4085004 DOI: 10.1371/journal.pone.0101900] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [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] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/12/2014] [Indexed: 12/20/2022] Open
Abstract
Estrogen exerts diverse biological effects in multiple tissues in both animals and humans. Much of the accumulated knowledge on the role of estrogen receptor (ER) in the heart has been obtained from studies using ovariectomized mice, whole body ER gene knock-out animal models, ex vivo heart studies, or from isolated cardiac myocytes. In light of the wide systemic influence of ER signaling in regulating a host of biological functions in multiple tissues, it is difficult to infer the direct role of ER on the heart. Therefore, we developed a mouse model with a cardiomyocyte-specific deletion of the ERα allele (cs-ERα−/−). Male and female cs-ERα−/− mice with age/sex-matched wild type controls were examined for differences in cardiac structure and function by echocardiogram and differential gene expression microarray analysis. Our study revealed sex-differences in structural parameters in the hearts of cs-ERα−/− mice, with minimal functional differences. Analysis of microarray data revealed differential variations in the expression of 208 genes affecting multiple transcriptional networks. Furthermore, we report sex-specific differences in the expression of 56 genes. Overall, we developed a mouse model with cardiac-specific deletion of ERα to characterize the role of ERα in the heart independent of systemic effects. Our results suggest that ERα is involved in controlling the expression of diverse genes and networks in the cardiomyocyte in a sex-dependent manner.
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Affiliation(s)
- Sriram Devanathan
- Department of Radiology, Washington University in St. Louis, Saint Louis, Missouri, United States of America
| | - Timothy Whitehead
- Department of Radiology, Washington University in St. Louis, Saint Louis, Missouri, United States of America
| | - George G. Schweitzer
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University in St. Louis, Saint Louis, Missouri, United States of America
| | - Nicole Fettig
- Department of Radiology, Washington University in St. Louis, Saint Louis, Missouri, United States of America
| | - Attila Kovacs
- Center for Cardiovascular Research, Department of Medicine, Washington University in St. Louis, Saint Louis, Missouri, United States of America
| | - Kenneth S. Korach
- Laboratory of Reproductive and Developmental Toxicology, Receptor Biology Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, United States of America
| | - Brian N. Finck
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University in St. Louis, Saint Louis, Missouri, United States of America
| | - Kooresh I. Shoghi
- Department of Radiology, Washington University in St. Louis, Saint Louis, Missouri, United States of America
- Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, Missouri, United States of America
- Division of Biology and Biomedical Sciences, Washington University in St. Louis, Saint Louis, Missouri, United States of America
- * E-mail:
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Hall AM, Soufi N, Chambers KT, Chen Z, Schweitzer GG, McCommis KS, Erion DM, Graham MJ, Su X, Finck BN. Abrogating monoacylglycerol acyltransferase activity in liver improves glucose tolerance and hepatic insulin signaling in obese mice. Diabetes 2014; 63:2284-96. [PMID: 24595352 PMCID: PMC4066334 DOI: 10.2337/db13-1502] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [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: 12/15/2022]
Abstract
Monoacylglycerol acyltransferase (MGAT) enzymes convert monoacylglycerol to diacylglycerol (DAG), a lipid that has been linked to the development of hepatic insulin resistance through activation of protein kinase C (PKC). The expression of genes that encode MGAT enzymes is induced in the livers of insulin-resistant human subjects with nonalcoholic fatty liver disease, but whether MGAT activation is causal of hepatic steatosis or insulin resistance is unknown. We show that the expression of Mogat1, which encodes MGAT1, and MGAT activity are also increased in diet-induced obese (DIO) and ob/obmice. To probe the metabolic effects of MGAT1 in the livers of obese mice, we administered antisense oligonucleotides (ASOs) against Mogat1 to DIO and ob/ob mice for 3 weeks. Knockdown of Mogat1 in liver, which reduced hepatic MGAT activity, did not affect hepatic triacylglycerol content and unexpectedly increased total DAG content. Mogat1 inhibition also increased both membrane and cytosolic compartment DAG levels. However, Mogat1 ASO treatment significantly improved glucose tolerance and hepatic insulin signaling in obese mice. In summary, inactivation of hepatic MGAT activity, which is markedly increased in obese mice, improved glucose tolerance and hepatic insulin signaling independent of changes in body weight, intrahepatic DAG and TAG content, and PKC signaling.
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Affiliation(s)
- Angela M Hall
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Nisreen Soufi
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Kari T Chambers
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Zhouji Chen
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - George G Schweitzer
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Kyle S McCommis
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Derek M Erion
- Cardiovascular, Metabolic, and Endocrine Diseases Research Unit, Pfizer Global Research and Development, Cambridge, MA
| | | | - Xiong Su
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MODepartment of Biochemistry and Molecular Biology, Medical College of Soochow University, Suzhou, China
| | - Brian N Finck
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
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Magkos F, Bradley D, Schweitzer GG, Finck BN, Eagon JC, Ilkayeva O, Newgard CB, Klein S. Effect of Roux-en-Y gastric bypass and laparoscopic adjustable gastric banding on branched-chain amino acid metabolism. Diabetes 2013; 62:2757-61. [PMID: 23610059 PMCID: PMC3717831 DOI: 10.2337/db13-0185] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [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: 01/18/2023]
Abstract
It has been hypothesized that a greater decline in circulating branched-chain amino acids (BCAAs) after weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery than after calorie restriction alone has independent effects on glucose homeostasis, possibly by decreased signaling through the mammalian target of rapamycin (mTOR). We evaluated plasma BCAAs and their C3 and C5 acylcarnitine metabolites, muscle mTOR phosphorylation, and insulin sensitivity (insulin-stimulated glucose Rd) in obese subjects before and after ~20% weight loss induced by RYGB (n = 10, BMI 45.6 ± 6.7 kg/m(2)) or laparoscopic adjustable gastric banding (LAGB) (n = 10, BMI 46.5 ± 8.8 kg/m(2)). Weight loss increased insulin-stimulated glucose Rd by ~55%, decreased total plasma BCAA and C3 and C5 acylcarnitine concentrations by 20-35%, and did not alter mTOR phosphorylation; no differences were detected between surgical groups (all P values for interaction >0.05). Insulin-stimulated glucose Rd correlated negatively with plasma BCAAs and with C3 and C5 acylcarnitine concentrations (r values -0.56 to -0.75, P < 0.05). These data demonstrate that weight loss induced by either LAGB or RYGB causes the same decline in circulating BCAAs and their C3 and C5 acylcarnitine metabolites. Plasma BCAA concentration is negatively associated with skeletal muscle insulin sensitivity, but the mechanism(s) responsible for this relationship is not known.
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Affiliation(s)
- Faidon Magkos
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine,Washington University School of Medicine, St. Louis, Missouri
| | - David Bradley
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine,Washington University School of Medicine, St. Louis, Missouri
| | - George G. Schweitzer
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine,Washington University School of Medicine, St. Louis, Missouri
| | - Brian N. Finck
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine,Washington University School of Medicine, St. Louis, Missouri
| | - J. Christopher Eagon
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine,Washington University School of Medicine, St. Louis, Missouri
| | - Olga Ilkayeva
- Sarah W. Stedman Nutrition and Metabolism Center, Departments of Pharmacology and Cancer Biology and Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Christopher B. Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Departments of Pharmacology and Cancer Biology and Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Samuel Klein
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine,Washington University School of Medicine, St. Louis, Missouri
- Corresponding author: Samuel Klein,
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Schweitzer GG, Arias EB, Cartee GD. Sustained postexercise increases in AS160 Thr642 and Ser588 phosphorylation in skeletal muscle without sustained increases in kinase phosphorylation. J Appl Physiol (1985) 2012; 113:1852-61. [PMID: 22936728 DOI: 10.1152/japplphysiol.00619.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Prior exercise by rats can induce a sustained increase in muscle Akt substrate of 160 kDa (AS160) phosphorylation on Thr(642) (pAS160(Thr642)). Because phosphorylation of AS160 on both AS160(Thr642) and AS160(Ser588) is important for insulin-stimulated glucose transport (GT), we determined if exercise would also induce a sustained increase in pAS160(Ser588) concomitant with persistently elevated pAS160(Thr642) and GT. Given that the mechanisms for sustained postexercise (PEX) effects on pAS160 were uncertain, we also studied the four kinases known to phosphorylate AS160 (Akt, AMPK, RSK, and SGK1). In addition, because the serine/threonine phosphatase(s) that dephosphorylate muscle AS160 were previously unidentified, we assessed the ability of four serine/threonine phosphatases (PP1, PP2A, PP2B, and PP2C) to dephosphorylate AS160. We also evaluated exercise effects on posttranslational modifications (Tyr(307) and Leu(309)) that regulate PP2A. In isolated epitrochlearis muscles from rats, GT at 3hPEX with insulin significantly (P < 0.05) exceeded SED controls. Muscles from 0hPEX vs. 0hSED and 3hPEX vs. 3hSED rats had greater pAS160(Thr642) and pAS160(Ser588). AMPK was the only kinase with greater phosphorylation at 0hPEX vs. 0hSED, and none had greater phosphorylation at 3hPEX vs. 3hSED. Each phosphatase was able to dephosphorylate pAS160(Thr642) and pAS160(Ser588) in cell-free assays. Exercise did not alter posttranslational modifications of PP2A. Our results revealed: 1) pAMPK as a potential trigger for increased pAS160(Thr642) and pAS160(Ser588) at 0hPEX; 2) PP1, PP2A, PP2B, and PP2C were each able to dephosphorylate AS160; and 3) sustained PEX-induced elevations of pAS160(Thr642) and pAS160(Ser588) were attributable to mechanisms other than persistent phosphorylation of known AS160 kinases or altered posttranslational modifications of PP2A.
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Affiliation(s)
- George G Schweitzer
- Muscle Biology Laboratory, School of Kinesiology, Muscle Biology Laboratory, 401 Washtenaw, Ann Arbor, MI48109-2214, USA
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Abstract
UNLABELLED A single exercise bout stimulates skeletal muscle glucose transport (GT) in the absence or presence of insulin. It has been suggested that the kallikrein-kinin system may contribute to exercise effects on both insulin-independent and insulin-dependent GT. Plasma kininogen, a key kallikrein-kinin system component, is a protein substrate for the enzyme kallikrein and the source of the peptide bradykinin. PURPOSE This study aimed to determine whether the postexercise (PEX) increase in insulin-dependent or insulin-independent GT is reduced in rats deficient in plasma kininogen versus normal rats. METHODS Male Brown Norway (BN) and Brown Norway Katholiek (BNK; plasma kininogen-deficient) rats were studied. BN and BNK rats were assigned to exercise (4×30-min swim) or sedentary (SED) groups. Rats were anesthetized immediately (0hPEX) or 3 h (3hPEX) after exercise. For 0hPEX and 0hSED rats, one epitrochlearis muscle per rat was used for AMPK phosphorylation and muscle glycogen analyses. The contralateral muscle was incubated with [H]-3-O-methylglucose (3-MG) for GT assay. For 3hPEX and 3hSED rats, one muscle from each rat was incubated without insulin, and the contralateral muscle was incubated with 60 μU·mL insulin, and both muscles were incubated with 3-MG for GT measurement. RESULTS For 0hPEX versus 0hSED, both BN and BNK rats had greater insulin-independent GT and AMPK phosphorylation with reduced glycogen after exercise. No genotype effects were found 0hPEX. There was a significant main effect of exercise (3hPEX>3hSED) and no interaction between exercise and genotype for basal or insulin-stimulated GT. CONCLUSIONS Plasma kininogen deficiency did not alter insulin-independent GT, AMPK phosphorylation, or glycogen depletion 0hPEX or insulin-dependent GT 3hPEX, suggesting that normal plasma kininogen is not essential for these important exercise effects.
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Affiliation(s)
- George G Schweitzer
- Muscle Biology Laboratory, School of Kinesiology, Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
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Schweitzer GG, Castorena CM, Hamada T, Funai K, Arias EB, Cartee GD. The B2 receptor of bradykinin is not essential for the post-exercise increase in glucose uptake by insulin-stimulated mouse skeletal muscle. Physiol Res 2011; 60:511-9. [PMID: 21401298 DOI: 10.33549/physiolres.932085] [Citation(s) in RCA: 9] [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: 11/25/2022] Open
Abstract
Bradykinin can enhance skeletal muscle glucose uptake (GU), and exercise increases both bradykinin production and muscle insulin sensitivity, but bradykinin's relationship with post-exercise insulin action is uncertain. Our primary aim was to determine if the B2 receptor of bradykinin (B2R) is essential for the post-exercise increase in GU by insulin-stimulated mouse soleus muscles. Wildtype (WT) and B2R knockout (B2RKO) mice were sedentary or performed 60 minutes of treadmill exercise. Isolated soleus muscles were incubated with [³H]-2-deoxyglucose +/-insulin (60 or 100 microU/ml). GU tended to be greater for WT vs. B2RKO soleus with 60 microU/ml insulin (P=0.166) and was significantly greater for muscles with 100 microU/ml insulin (P<0.05). Both genotypes had significant exercise-induced reductions (P<0.05) in glycemia and insulinemia, and the decrements for glucose (approximately 14 %) and insulin (approximately 55 %) were similar between genotypes. GU tended to be greater for exercised vs. sedentary soleus with 60 microU/ml insulin (P=0.063) and was significantly greater for muscles with 100 microU/ml insulin (P<0.05). There were no significant interactions between genotype and exercise for blood glucose, plasma insulin or GU. These results indicate that the B2R is not essential for the exercise-induced decrements in blood glucose or plasma insulin or for the post-exercise increase in GU by insulin-stimulated mouse soleus muscle.
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Affiliation(s)
- G G Schweitzer
- Muscle Biology Laboratory, University of Michigan, School of Kinesiology, Ann Arbor, MI, USA
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Schweitzer GG, Arias EB, Cartee GD. The Increased Insulin-stimulated Glucose Transport in Skeletal Muscle Post-Exercise Is Undiminished in Kininogen Deficient Rats. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000389351.27709.5c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Funai K, Schweitzer GG, Castorena CM, Kanzaki M, Cartee GD. In vivo exercise followed by in vitro contraction additively elevates subsequent insulin-stimulated glucose transport by rat skeletal muscle. Am J Physiol Endocrinol Metab 2010; 298:E999-1010. [PMID: 20179245 PMCID: PMC2867374 DOI: 10.1152/ajpendo.00758.2009] [Citation(s) in RCA: 52] [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: 11/22/2022]
Abstract
The cellular mechanisms whereby prior exercise enhances insulin-stimulated glucose transport (GT) are not well understood. Previous studies suggested that a prolonged increase in phosphorylation of Akt substrate of 160 kDa (AS160) may be important for the postexercise increase in insulin sensitivity. In the current study, the effects of in vivo exercise and in vitro contraction on subsequent insulin-stimulated GT were studied separately and together. Consistent with results from previous studies, prior exercise resulted in an increase in AS160 (642)Thr phosphorylation immediately after exercise in rat epitrochlearis muscles, and this increase remained 3 h postexercise concomitant with enhanced insulin-stimulated GT. For experiments with in vitro contraction, isolated rat epitrochlearis muscles were electrically stimulated to contract in the presence or absence of rat serum. As expected, insulin-stimulated GT measured 3 h after electrical stimulation in serum, but not after electrical stimulation without serum, exceeded resting controls. Immediately after electrical stimulation with or without serum, phosphorylation of both AS160 (detected by phospho-Akt substrate, PAS, antibody, or phospho-(642)Thr antibody) and its paralog TBC1D1 (detected by phospho-(237)Ser antibody) was increased. However, both AS160 and TBC1D1 phosphorylation had reversed to resting values at 3 h poststimulation with or without serum. Increasing the amount of exercise (from 1 to 2 h) or electrical stimulation (from 5 to 10 tetani) did not further elevate insulin-stimulated GT. In contrast, the combination of prior exercise and electrical stimulation had an additive effect on the subsequent increase in insulin-stimulated GT, suggesting that these exercise and electrical stimulation protocols may amplify insulin-stimulated GT through distinct mechanisms, with a persistent increase in AS160 phosphorylation potentially important for increased insulin sensitivity after exercise, but not after in vitro contraction.
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Affiliation(s)
- Katsuhiko Funai
- University of Michigan, School of Kinesiology, Muscle Biology Laboratory, 401 Washtenaw Ave., Ann Arbor, MI 48109-2214, USA
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Funai K, Schweitzer GG, Sharma N, Kanzaki M, Cartee GD. Increased AS160 phosphorylation, but not TBC1D1 phosphorylation, with increased postexercise insulin sensitivity in rat skeletal muscle. Am J Physiol Endocrinol Metab 2009; 297:E242-51. [PMID: 19435856 PMCID: PMC2711658 DOI: 10.1152/ajpendo.00194.2009] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [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] [Indexed: 11/22/2022]
Abstract
A single exercise bout can increase insulin-independent glucose transport immediately postexercise and insulin-dependent glucose transport (GT) for several hours postexercise. Akt substrate of 160 kDa (AS160) and TBC1D1 are paralog Rab GTPase-activating proteins that have been proposed to contribute to these exercise effects. Previous research demonstrated greater AS160 and Akt threonine phosphorylation in rat skeletal muscle at 3-4 h postexercise concomitant with enhanced insulin-stimulated GT. To further probe whether these signaling events or TBC1D1 phosphorylation were important for the enhanced postexercise insulin-stimulated GT, male Wistar rats were studied using four experimental protocols (2-h swim exercise, differing with regard to timing of muscle sampling and whether food was provided postexercise) that were known to vary in their influence of insulin-independent and insulin-dependent GT postexercise. The results indicated that, in isolated rat epitrochlearis muscle, 1) elevated phosphorylation of AS160 (measured using anti-phospho-Akt substrate, PAS-AS160, and phosphospecific anti-Thr(642)-AS160, pThr(642)-AS160) consistently tracked with elevated insulin-stimulated GT; 2) PAS-TBC1D1 was not different from sedentary values at 3 or 27 h postexercise, when insulin sensitivity was increased; 3) insulin-stimulated Akt activity was not increased postexercise in muscles with increased insulin sensitivity; 4) PAS-TBC1D1 was increased immediately postexercise, when insulin-independent GT was elevated, and reversed at 3 and 27 h postexercise, when insulin-independent GT was also reversed; and 5) there was no significant effect of exercise or insulin on total abundance of AS160, TBC1D1, Akt, or GLUT4 protein with any of the protocols. The results are consistent with increased AS160 phosphorylation (PAS-AS160 or pThr(642)-AS160) but not increased PAS-TBC1D1 or Akt activity, which is important for increased postexercise insulin-stimulated GT in rat skeletal muscle. They also support the idea that increased TBC1D1 phosphorylation may play a role in the insulin-independent increase in GT postexercise.
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Affiliation(s)
- Katsuhiko Funai
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI 48109-2214, USA
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Blair DR, Funai K, Schweitzer GG, Cartee GD. A myosin II ATPase inhibitor reduces force production, glucose transport, and phosphorylation of AMPK and TBC1D1 in electrically stimulated rat skeletal muscle. Am J Physiol Endocrinol Metab 2009; 296:E993-E1002. [PMID: 19190254 PMCID: PMC2681314 DOI: 10.1152/ajpendo.91003.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Contraction-stimulated glucose transport by skeletal muscle appears to be caused by the cumulative effects of multiple inputs [potentially including AMP-activated protein kinase (AMPK), Ca(2+) flux, and force production], making it challenging to isolate the roles of these putative regulatory factors. To distinguish the effects of force production from the direct consequences of Ca(2+) flux, the predominantly type II rat epitrochlearis muscle was incubated without (vehicle) or with N-benzyl-p-toluenesulfonamide (BTS), a highly specific myosin II ATPase inhibitor that prevents force production by electrically stimulated (ES) type II fibers without altering cytosolic Ca(2+). In ES muscles, BTS vs. vehicle had an 84% reduction in force production and a 57% decrement in contraction-stimulated 3-O-methylglucose transport (3MGT). BTS did not alter the ES increase in phosphorylation of CaMKII (indicative of cytosolic Ca(2+)) or the amount of glycogen depletion. ES caused significant reductions in ATP (48%) and phosphocreatine (67%) concentrations for vehicle-treated muscles. For BTS-treated muscles, ES did not reduce ATP and caused only a 42% decrease in phosphocreatine. There was an ES increase in phosphorylation of AMPK, acetyl-CoA carboxylase (an AMPK substrate), and TBC1D1 for vehicle-treated muscles but not for BTS-treated muscles. These results point toward an essential role for tension-related events, including AMPK activation, in the 57% contraction-stimulated increase in 3MGT that was inhibited by BTS and further suggest a possible role for TBC1D1 phosphorylation. Non-tension-related events (e.g., increased cytosolic Ca(2+) rather than increased AMPK and TBC1D1 phosphorylation) are implicated in the contraction-stimulated increase in 3MGT that persisted in the presence of BTS.
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Affiliation(s)
- David R Blair
- University of Michigan, Division of Kinesiology, Ann Arbor, MI 48109-2214, USA
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Abstract
Two novel transgenic (Tg) strains were created expressing hen egg-white lysozyme (HEL) in a pancreas-specific fashion. RmHP.111 mice had levels of HEL per cell similar to that of the established ILK-3 strain, while RmHP.117 mice had 10-fold lower levels (50,000 molecules per cell). When bred to 3A9 TCR Tg mice, negative selection occurred equally in all three double-Tg combinations, yet only ILK-3 x 3A9 and RmHP.111 x 3A9 mice became diabetic. Additionally, activated 3A9 cells readily transferred diabetes into ILK-3 or RmHP.111 mice, but only marginally into the RmHP.117 strain. In the peripancreatic lymph node, division of naive 3A9 cells was similar between RmHP.111 and RmHP.117 strains, but pancreatic APCs from RmHP.111 x 3A9 mice stimulated HEL-reactive cells to a much greater degree than those from RmHP.117 x 3A9 mice. In this model, diabetes was dependent upon both initial priming in the peripancreatic lymph node and subsequent presentation in the pancreas, with disease incidence predicted by the beta cell level of autoantigen.
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Affiliation(s)
- Craig A Byersdorfer
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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