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Vanweert F, Schrauwen P, Phielix E. Role of branched-chain amino acid metabolism in the pathogenesis of obesity and type 2 diabetes-related metabolic disturbances BCAA metabolism in type 2 diabetes. Nutr Diabetes 2022; 12:35. [PMID: 35931683 PMCID: PMC9356071 DOI: 10.1038/s41387-022-00213-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 06/15/2022] [Accepted: 07/05/2022] [Indexed: 12/23/2022] Open
Abstract
Branched-chain amino acid (BCAA) catabolism has been considered to have an emerging role in the pathogenesis of metabolic disturbances in obesity and type 2 diabetes (T2D). Several studies showed elevated plasma BCAA levels in humans with insulin resistance and patients with T2D, although the underlying reason is unknown. Dysfunctional BCAA catabolism could theoretically be an underlying factor. In vitro and animal work collectively show that modulation of the BCAA catabolic pathway alters key metabolic processes affecting glucose homeostasis, although an integrated understanding of tissue-specific BCAA catabolism remains largely unknown, especially in humans. Proof-of-concept studies in rodents -and to a lesser extent in humans – strongly suggest that enhancing BCAA catabolism improves glucose homeostasis in metabolic disorders, such as obesity and T2D. In this review, we discuss several hypothesized mechanistic links between BCAA catabolism and insulin resistance and overview current available tools to modulate BCAA catabolism in vivo. Furthermore, this review considers whether enhancing BCAA catabolism forms a potential future treatment strategy to promote metabolic health in insulin resistance and T2D.
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Affiliation(s)
- Froukje Vanweert
- Department of Nutrition and Movement Sciences, NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Patrick Schrauwen
- Department of Nutrition and Movement Sciences, NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Esther Phielix
- Department of Nutrition and Movement Sciences, NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands.
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Exercise Enhances Branched-Chain Amino Acid Catabolism and Decreases Cardiac Vulnerability to Myocardial Ischemic Injury. Cells 2022; 11:cells11101706. [PMID: 35626742 PMCID: PMC9139679 DOI: 10.3390/cells11101706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/06/2022] [Accepted: 05/11/2022] [Indexed: 11/17/2022] Open
Abstract
Long-term exercise-induced metabolic adaptations occupy a central position in exercise-afforded cardiac benefits. Emerging evidence suggests that branched-chain amino acid (BCAA) catabolic defect contributes to cardiac dysfunction in multiple cardiometabolic diseases. However, the role of BCAA catabolism in exercise-afforded cardiac benefits remains unknown. Here, we show that exercise improves BCAA catabolism and thus reduce cardiac vulnerability to myocardial ischemic injury. Exercise increased circulating BCAA levels in both humans (male adolescent athletes) and mice (following an 8-week swimming intervention). It increased the expression of mitochondrial localized 2C-type serine-threonine protein phosphatase (PP2Cm), a key enzyme in regulating BCAA catabolism, and decreased BCAA accumulation in mouse hearts, indicating an increase in BCAA catabolism. Pharmacological promotion of BCAA catabolism protected the mouse heart against myocardial infarction (MI) induced by permanent ligation of the left descending coronary artery. Although cardiac-specific PP2Cm knockout showed no significant effects on cardiac structural and functional adaptations to exercise, it blunted the cardioprotective effects of exercise against MI. Mechanistically, exercise alleviated BCAA accumulation and subsequently inactivated the mammalian target of rapamycin in MI hearts. These results showed that exercise elevated BCAA catabolism and protected the heart against myocardial ischemic injury, reinforcing the role of exercise in the promotion of cardiac health.
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3
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Mann G, Mora S, Madu G, Adegoke OAJ. Branched-chain Amino Acids: Catabolism in Skeletal Muscle and Implications for Muscle and Whole-body Metabolism. Front Physiol 2021; 12:702826. [PMID: 34354601 PMCID: PMC8329528 DOI: 10.3389/fphys.2021.702826] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 06/24/2021] [Indexed: 12/20/2022] Open
Abstract
Branched-chain amino acids (BCAAs) are critical for skeletal muscle and whole-body anabolism and energy homeostasis. They also serve as signaling molecules, for example, being able to activate mammalian/mechanistic target of rapamycin complex 1 (mTORC1). This has implication for macronutrient metabolism. However, elevated circulating levels of BCAAs and of their ketoacids as well as impaired catabolism of these amino acids (AAs) are implicated in the development of insulin resistance and its sequelae, including type 2 diabetes, cardiovascular disease, and of some cancers, although other studies indicate supplements of these AAs may help in the management of some chronic diseases. Here, we first reviewed the catabolism of these AAs especially in skeletal muscle as this tissue contributes the most to whole body disposal of the BCAA. We then reviewed emerging mechanisms of control of enzymes involved in regulating BCAA catabolism. Such mechanisms include regulation of their abundance by microRNA and by post translational modifications such as phosphorylation, acetylation, and ubiquitination. We also reviewed implications of impaired metabolism of BCAA for muscle and whole-body metabolism. We comment on outstanding questions in the regulation of catabolism of these AAs, including regulation of the abundance and post-transcriptional/post-translational modification of enzymes that regulate BCAA catabolism, as well the impact of circadian rhythm, age and mTORC1 on these enzymes. Answers to such questions may facilitate emergence of treatment/management options that can help patients suffering from chronic diseases linked to impaired metabolism of the BCAAs.
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Affiliation(s)
| | | | | | - Olasunkanmi A. J. Adegoke
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
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Urakawa S, Takamoto K, Nakamura T, Sakai S, Matsuda T, Taguchi T, Mizumura K, Ono T, Nishijo H. Manual therapy ameliorates delayed-onset muscle soreness and alters muscle metabolites in rats. Physiol Rep 2015; 3:3/2/e12279. [PMID: 25713324 PMCID: PMC4393190 DOI: 10.14814/phy2.12279] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Delayed-onset muscle soreness (DOMS) can be induced by lengthening contraction (LC); it can be characterized by tenderness and movement-related pain in the exercised muscle. Manual therapy (MT), including compression of exercised muscles, is widely used as physical rehabilitation to reduce pain and promote functional recovery. Although MT is beneficial for reducing musculoskeletal pain (i.e. DOMS), the physiological mechanisms of MT remain unclear. In the present study, we first developed an animal model of MT in DOMS; LC was applied to the rat gastrocnemius muscle under anesthesia, which induced mechanical hyperalgesia 2–4 days after LC. MT (manual compression) ameliorated mechanical hyperalgesia. Then, we used capillary electrophoresis time-of-flight mass spectroscopy (CE-TOFMS) to investigate early effects of MT on the metabolite profiles of the muscle experiencing DOMS. The rats were divided into the following three groups; (1) normal controls, (2) rats with LC application (LC group), and (3) rats undergoing MT after LC (LC + MT group). According to the CE-TOFMS analysis, a total of 171 metabolites were detected among the three groups, and 19 of these metabolites were significant among the groups. Furthermore, the concentrations of eight metabolites, including branched-chain amino acids, carnitine, and malic acid, were significantly different between the LC + MT and LC groups. The results suggest that MT significantly altered metabolite profiles in DOMS. According to our findings and previous data regarding metabolites in mitochondrial metabolism, the ameliorative effects of MT might be mediated partly through alterations in metabolites associated with mitochondrial respiration.
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Affiliation(s)
- Susumu Urakawa
- Department of Judo Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Kouichi Takamoto
- Department of Judo Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Tomoya Nakamura
- Department of System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Shigekazu Sakai
- Department of Judo Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Teru Matsuda
- Department of Physical Therapy, College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Toru Taguchi
- Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Kazue Mizumura
- Department of Physical Therapy, College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Taketoshi Ono
- Department of Judo Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Hisao Nishijo
- Department of System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
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5
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Abstract
Branched-chain amino acids (BCAAs) are important nutrient signals that have direct and indirect effects. Frequently, BCAAs have been reported to mediate antiobesity effects, especially in rodent models. However, circulating levels of BCAAs tend to be increased in individuals with obesity and are associated with worse metabolic health and future insulin resistance or type 2 diabetes mellitus (T2DM). A hypothesized mechanism linking increased levels of BCAAs and T2DM involves leucine-mediated activation of the mammalian target of rapamycin complex 1 (mTORC1), which results in uncoupling of insulin signalling at an early stage. A BCAA dysmetabolism model proposes that the accumulation of mitotoxic metabolites (and not BCAAs per se) promotes β-cell mitochondrial dysfunction, stress signalling and apoptosis associated with T2DM. Alternatively, insulin resistance might promote aminoacidaemia by increasing the protein degradation that insulin normally suppresses, and/or by eliciting an impairment of efficient BCAA oxidative metabolism in some tissues. Whether and how impaired BCAA metabolism might occur in obesity is discussed in this Review. Research on the role of individual and model-dependent differences in BCAA metabolism is needed, as several genes (BCKDHA, PPM1K, IVD and KLF15) have been designated as candidate genes for obesity and/or T2DM in humans, and distinct phenotypes of tissue-specific branched chain ketoacid dehydrogenase complex activity have been detected in animal models of obesity and T2DM.
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Affiliation(s)
- Christopher J Lynch
- Cellular and Molecular Physiology Department, The Pennsylvania State University, 500 University Drive, MC-H166, Hershey, PA 17033, USA
| | - Sean H Adams
- Arkansas Children's Nutrition Center, and Department of Pediatrics, University of Arkansas for Medical Sciences, 15 Children's Way, Little Rock, AR 72202, USA
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Plasma branched-chain amino acid levels and muscle energy metabolism in patients with chronic obstructive pulmonary disease. Clin Nutr 2009; 28:203-8. [PMID: 19250720 DOI: 10.1016/j.clnu.2009.01.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 01/11/2009] [Accepted: 01/29/2009] [Indexed: 11/21/2022]
Abstract
BACKGROUND & AIMS Although several studies have shown that plasma concentrations of branched-chain amino acids (BCAAs) are reduced in patients with chronic obstructive pulmonary disease (COPD), little is understood about how low concentrations of BCAAs limit exercise in such patients. The present study investigated whether plasma BCAAs are related to energy metabolism in exercising muscle using (31)P-magnetic resonance spectroscopy (MRS). METHODS We analyzed the plasma amino acid profiles of 23 male patients with COPD (aged 69.2+/-5.1 years) and of 7 healthy males (aged 64.1+/-6.0 years). We normalized the exercise intensity of repetitive lifting by adjusting the weight to 7% of the maximal grip power. The intracellular pH and the phosphocreatine (PCr) index (PCr/(PCr+Pi); Pi, inorganic phosphate) were calculated from MR spectra. We evaluated the relationship between intracellular pH and PCr index at the completion of exercise and the plasma BCAA concentration. RESULTS Glutamine concentrations were elevated in patients with COPD compared with healthy individuals. Plasma concentrations of BCAAs correlated with intracellular pH and PCr index at the completion of exercise. CONCLUSIONS The findings are consistent with the notion that BCAAs affect muscle energy metabolism during exercise in patients with COPD.
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7
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Devries MC, Tarnopolsky MA. Muscle Physiology in Healthy Men and Women and Those with Metabolic Myopathies. Phys Med Rehabil Clin N Am 2009; 20:101-31, viii-ix. [DOI: 10.1016/j.pmr.2008.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Muscle Physiology in Healthy Men and Women and Those with Metabolic Myopathies. Neurol Clin 2008; 26:115-48; ix. [DOI: 10.1016/j.ncl.2007.11.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Howarth KR, Burgomaster KA, Phillips SM, Gibala MJ. Exercise training increases branched-chain oxoacid dehydrogenase kinase content in human skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1335-41. [PMID: 17581840 DOI: 10.1152/ajpregu.00115.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The branched-chain oxoacid dehydrogenase complex (BCOAD) is rate determining for the oxidation of branched-chain amino acids (BCAAs) in skeletal muscle. Exercise training blunts the acute exercise-induced activation of BCOAD (BCOADa) in human skeletal muscle (McKenzie S, Phillips SM, Carter SL, Lowther S, Gibala MJ, Tarnopolsky MA. Am J Physiol Endocrinol Metab 278: E580–E587, 2000); however, the mechanism is unknown. We hypothesized that training would increase the muscle protein content of BCOAD kinase, the enzyme responsible for inactivation of BCOAD by phosphorylation. Twenty subjects [23 ± 1 yr; peak oxygen uptake (V̇o2peak) = 41 ± 2 ml·kg−1·min−1] performed 6 wk of either high-intensity interval or continuous moderate-intensity training on a cycle ergometer ( n = 10/group). Before and after training, subjects performed 60 min of cycling at 65% of pretraining V̇o2peak, and needle biopsy samples (vastus lateralis) were obtained before and immediately after exercise. The effect of training was demonstrated by an increased V̇o2peak, increased citrate synthase maximal activity, and reduced muscle glycogenolysis during exercise, with no difference between groups (main effects, P < 0.05). BCOADa was lower after training (main effect, P < 0.05), and this was associated with a ∼30% increase in BCOAD kinase protein content (main effect, P < 0.05). We conclude that the increased protein content of BCOAD kinase may be involved in the mechanism for reduced BCOADa after exercise training in human skeletal muscle. These data also highlight differences in models used to study the regulation of skeletal muscle BCAA metabolism, since exercise training was previously reported to increase BCOADa during exercise and decrease BCOAD kinase content in rats (Fujii H, Shimomura Y, Murakami T, Nakai N, Sato T, Suzuki M, Harris RA. Biochem Mol Biol Int 44: 1211–1216, 1998).
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Affiliation(s)
- Krista R Howarth
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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10
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Shimomura Y, Yamamoto Y, Bajotto G, Sato J, Murakami T, Shimomura N, Kobayashi H, Mawatari K. Nutraceutical effects of branched-chain amino acids on skeletal muscle. J Nutr 2006; 136:529S-532S. [PMID: 16424141 DOI: 10.1093/jn/136.2.529s] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
BCAA catabolism in skeletal muscle is regulated by the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, located at the second step in the BCAA catabolic pathway. The activity of the BCKDH complex is regulated by a phosphorylation/dephosphorylation cycle. Almost all of BCKDH complex in skeletal muscle under normal and resting conditions is in an inactive/phosphorylated state, which may contribute to muscle protein synthesis and muscle growth. Exercise activates the muscle BCKDH complex, resulting in enhanced BCAA catabolism. Therefore, exercise may increase the BCAA requirement. It has been reported that BCAA supplementation before exercise attenuates the breakdown of muscle proteins during exercise in humans and that leucine strongly promotes protein synthesis in skeletal muscle in humans and rats, suggesting that a BCAA supplement may attenuate muscle damage induced by exercise and promote recovery from the damage. We have examined the effects of BCAA supplementation on delayed-onset muscle soreness (DOMS) and muscle fatigue induced by squat exercise in humans. The results obtained showed that BCAA supplementation prior to squat exercise decreased DOMS and muscle fatigue occurring for a few days after exercise. These findings suggest that BCAAs may be useful for muscle recovery following exercise.
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Affiliation(s)
- Yoshiharu Shimomura
- Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya, Japan.
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11
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Shimomura Y, Honda T, Shiraki M, Murakami T, Sato J, Kobayashi H, Mawatari K, Obayashi M, Harris RA. Branched-chain amino acid catabolism in exercise and liver disease. J Nutr 2006; 136:250S-3S. [PMID: 16365092 DOI: 10.1093/jn/136.1.250s] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, the enzyme catalyst for the second step of the BCAA catabolic pathway, plays a central role in the regulation of BCAA catabolism. The activity of the complex is regulated by a covalent modification cycle in which phosphorylation by BCKDH kinase inactivates and dephosphorylation by BCKDH phosphatase activates the complex. Many studies suggest that control of the activity of the kinase is a primary determinant of the activity of the complex. The kinase exists at all times in the mitochondrial matrix space in two forms, with a large amount being free and a smaller amount bound rather tightly to the BCKDH complex. Only the bound form of the kinase appears to be catalytically active and, therefore, responsible for phosphorylation and inactivation of the complex. alpha-Ketoisocaproate, the transamination product of leucine and the most important known physiological inhibitor of BCKDH kinase, promotes release of the kinase from the complex. alpha-Chloroisocaproate, the analogue of leucine and the most potent known inhibitor of the kinase, is more effective than alpha-ketoisocaproate in promoting release of BCKDH kinase from the complex. Exercise and chronic liver disease (liver cirrhosis) likewise decrease the amount of the kinase bound to the complex in rat liver. The resulting activation of the BCKDH complex appears responsible for the increase in BCAA catabolism caused by exercise and liver cirrhosis. Our findings support the use of BCAA supplements for patients with liver cirrhosis.
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Affiliation(s)
- Yoshiharu Shimomura
- Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
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12
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Shimomura Y, Murakami T, Nakai N, Nagasaki M, Harris RA. Exercise promotes BCAA catabolism: effects of BCAA supplementation on skeletal muscle during exercise. J Nutr 2004; 134:1583S-1587S. [PMID: 15173434 DOI: 10.1093/jn/134.6.1583s] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Branched-chain amino acids (BCAAs) are essential amino acids that can be oxidized in skeletal muscle. It is known that BCAA oxidation is promoted by exercise. The mechanism responsible for this phenomenon is attributed to activation of the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, which catalyzes the second-step reaction of the BCAA catabolic pathway and is the rate-limiting enzyme in the pathway. This enzyme complex is regulated by a phosphorylation-dephosphorylation cycle. The BCKDH kinase is responsible for inactivation of the complex by phosphorylation, and the activity of the kinase is inversely correlated with the activity state of the BCKDH complex, which suggests that the kinase is the primary regulator of the complex. We found recently that administration of ligands for peroxisome proliferator-activated receptor-alpha (PPARalpha) in rats caused activation of the hepatic BCKDH complex in association with a decrease in the kinase activity, which suggests that promotion of fatty acid oxidation upregulates the BCAA catabolism. Long-chain fatty acids are ligands for PPARalpha, and the fatty acid oxidation is promoted by several physiological conditions including exercise. These findings suggest that fatty acids may be one of the regulators of BCAA catabolism and that the BCAA requirement is increased by exercise. Furthermore, BCAA supplementation before and after exercise has beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis; this suggests the possibility that BCAAs are a useful supplement in relation to exercise and sports.
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Affiliation(s)
- Yoshiharu Shimomura
- Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
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Xu M, Nagasaki M, Obayashi M, Sato Y, Tamura T, Shimomura Y. Mechanism of activation of branched-chain alpha-keto acid dehydrogenase complex by exercise. Biochem Biophys Res Commun 2001; 287:752-6. [PMID: 11563860 DOI: 10.1006/bbrc.2001.5647] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex catalyzes the committed step of branched-chain amino acid catabolism, and its activity is regulated by the phosphorylation-dephosphorylation cycle. BCKDH kinase is responsible for inactivation of the complex by phosphorylation. In the present study, we examined acute exercise on the activity state of the complex as well as the amounts of bound and free forms of the kinase in rat liver and skeletal muscle. Acute exercise activated the complex in association with a decrease in the bound form of kinase in both liver and muscle. The free form of kinase in both tissues was slightly increased but the total amount of the kinase was not affected by acute exercise. The protein amount ratio of bound kinase to E1beta component of the complex was much higher in muscle than in the liver of rats, reflecting the low activity state of the complex in muscle. These results suggest that the amount of the bound kinase plays an important role in regulation of the activity state of the complex. We propose that the alteration in the amount of bound BCKDH kinase is a short-term regulatory mechanism for determining the activity of BCKDH complex.
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Affiliation(s)
- M Xu
- Department of Sports Medicine, Nagoya University, Nagoya, 464-8601, Japan
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14
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Costeas PA, Chinsky JM. Glucocorticoid regulation of branched-chain alpha-ketoacid dehydrogenase E2 subunit gene expression. Biochem J 2000; 347:449-57. [PMID: 10749674 PMCID: PMC1220977 DOI: 10.1042/0264-6021:3470449] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Regulation of the mammalian branched-chain alpha-ketoacid dehydrogenase complex (BCKAD) occurs under a variety of stressful conditions associated with changes in circulating glucocorticoids. Multiple levels of regulation in hepatocytes, including alteration of the levels of the structural subunits available for assembly (E1, alpha-ketoacid decarboxylase; E2, dihydrolipoamide acyltransferase; and E3, dihydrolipoamide dehydrogenase), as well as BCKAD kinase, which serves to phosphorylate the E1alpha subunit and inactivate complex activity, have been proposed. The direct role of glucocorticoids in regulating the expression of the murine gene encoding the major BCKAD subunit E2, upon which the other BCKAD subunits assemble, was therefore examined. Deletion analysis of the 5' proximal 7.0 kb of the murine E2 promoter sequence, using E2 promoter/luciferase expression minigene plasmids introduced into the hepatic H4IIEC3 cell line, suggested a promoter proximal region responsive to glucocorticoid regulation. Linker-scanning mutagenesis combined with deletion analysis established this functional glucocorticoid-responsive unit (GRU) to be located near the murine E2 proximal promoter site at -140 to -70 bp upstream from the transcription initiation site. The presence of this region in plasmid minigenes, containing varying amounts of the murine genomic sequence 5' upstream from proximal E2 promoter sequences, conferred 2-10 fold increases in luciferase reporter gene expression in H4IIEC3 cells, whether introduced by transient transfection or following co-selection for stable transfectants. The GRU region itself appeared to contain multiple interacting elements that combine to regulate overall E2 promoter activity in response to changing physiological conditions associated with varying concentrations of glucocorticoids and likely other hormonal effectors.
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Affiliation(s)
- P A Costeas
- Division of Human Genetics, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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15
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Kobayashi R, Shimomura Y, Otsuka M, Popov KM, Harris RA. Experimental hyperthyroidism causes inactivation of the branched-chain alpha-ketoacid dehydrogenase complex in rat liver. Arch Biochem Biophys 2000; 375:55-61. [PMID: 10683248 DOI: 10.1006/abbi.1999.1635] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hyperthyroidism induced by 3-day treatment of rats with thyroid hormone (T(3); 3,5,3'-triiodothyronine) at 0.1 or 1 mg/kg body wt/day resulted in a reduced activity state (% of enzyme in its active, dephosphorylated state) of the hepatic branched-chain alpha-ketoacid dehydrogenase (BCKDH) complex. One treatment with 0.1 mg T(3)/kg body wt caused a significant effect on the activity state of BCKDH complex after 24 h, indicating that the reduction of the activity state was triggered by the first administration of T(3). Hyperthyroidism also caused a stable increase in BCKDH kinase activity, the enzyme responsible for phosphorylation and inactivation of the BCKDH complex, suggesting that T(3) caused inactivation of the BCKDH complex by induction of its kinase. Western blot analysis also revealed increased amounts of BCKDH kinase protein in response to hyperthyroidism. No change in the plasma levels of branched-chain alpha-keto acids was observed in T(3)-treated rats, arguing against an involvement of these known regulators of BCKDH kinase activity. Inactivation of the hepatic BCKDH complex as a consequence of overexpression of its kinase may save the essential branched-chain amino acids for protein synthesis during hyperthyroidism.
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Affiliation(s)
- R Kobayashi
- Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana, 46202-5122, USA
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Lombardo YB, Serdikoff C, Thamotharan M, Paul HS, Adibi SA. Inverse alterations of BCKA dehydrogenase activity in cardiac and skeletal muscles of diabetic rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E685-92. [PMID: 10516128 DOI: 10.1152/ajpendo.1999.277.4.e685] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rat cardiac and skeletal muscles, which have been used as model tissues for studies of regulation of branched-chain alpha-keto acid (BCKA) oxidation, vary greatly in the activity state of their BCKA dehydrogenase. In the present experiment, we have investigated whether they also vary in response of their BCKA dehydrogenase to a metabolic alteration such as diabetes and, if so, to investigate the mechanism that underlies the difference. Diabetes was produced by depriving streptozotocin-treated rats of insulin administration for 96 h. The investigation of BCKA dehydrogenase in the skeletal muscle (gastrocnemius) showed that diabetes 1) increased its activity, 2) increased the protein and gene expressions of all of its subunits (E(1)alpha, E(1)beta, E(2)), 3) increased its activity state, 4) decreased the rate of its inactivation, and 5) decreased the protein expression of its associated kinase (BCKAD kinase) without affecting its gene expression. In sharp contrast, the investigation of BCKA dehydrogenase in the cardiac muscle showed that diabetes 1) decreased its activity, 2) had no effect on either protein or gene expression of any of its subunits, 3) decreased its activity state, 4) increased its rate of inactivation, and 5) increased both the protein and gene expressions of its associated kinase. In conclusion, our data suggest that, in diabetes, the protein expression of BCKAD kinase is downregulated posttranscriptionally in the skeletal muscle, whereas it is upregulated pretranslationally in the cardiac muscle, causing inverse alterations of BCKA dehydrogenase activity in these muscles.
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Affiliation(s)
- Y B Lombardo
- Clinical Nutrition Research Unit, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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17
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DeSantiago S, Torres N, Suryawan A, Tovar AR, Hutson SM. Regulation of branched-chain amino acid metabolism in the lactating rat. J Nutr 1998; 128:1165-71. [PMID: 9649601 DOI: 10.1093/jn/128.7.1165] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There is evidence that during lactation, uptake of the essential branched-chain amino acids (BCAA) by mammary glands exceeds their output in milk protein. In this study, we have measured the potential of lactating rats to catabolize BCAA. The activity, relative protein and specific mRNA levels of the first two enzymes in the BCAA catabolic pathway, branched-chain aminotransferase (BCAT) and branched-chain alpha-keto acid dehydrogenase (BCKD), were measured in mammary gland, liver and skeletal muscle obtained from rat dams at peak lactation (12 d), from rat dams 24 h after weaning at peak lactation and from age-matched virgin controls. Western analysis showed that the mitochondrial BCATm isoenzyme was found in mammary gland. Comparison of lactating and control rats revealed that tissue BCATm activity, protein and mRNA were at least 10-fold higher in mammary tissue during lactation. Values were 1.3- to 1. 9-fold higher after 24 h of weaning. In mammary gland of lactating rats, the BCKD complex was fully active. In virgin controls and weaning dams, only about 20% of the complex was in the active state. Hypertrophy of the liver and mammary gland during lactation resulted in a 73% increase in total oxidative capacity in lactating rats. The results are consistent with increased expression of the BCATm gene in the mammary gland during lactation, whereas oxidation appears to be regulated primarily by changes in activity state (phosphorylation state) of BCKD.
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Affiliation(s)
- S DeSantiago
- Departamento de Fisiología de la Nutrición, Instituto Nacional de la Nutrición Salvador Zubirán, D. F. 14000, México
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Costeas PA, Chinsky JM. Effects of insulin on the regulation of branched-chain alpha-keto acid dehydrogenase E1 alpha subunit gene expression. Biochem J 1996; 318 ( Pt 1):85-92. [PMID: 8761456 PMCID: PMC1217592 DOI: 10.1042/bj3180085] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Alterations in dietary intake, especially of protein, may produce changes in the hepatic levels of the branched-chain alpha-keto acid dehydrogenase (BCKAD) complex. The possible role of insulin in the regulation of these observed changes in hepatic capacity for BCKAD expression was therefore examined. Steady-state RNA levels encoding three of the subunits, E1 alpha, E1 beta and E2, increased by 2-4-fold in the livers of mice starved for 3 days, a known hypoinsulinaemic state. In contrast, the levels of E1 beta and E2, but not E1 alpha, RNA were decreased when mice were fed 0% protein diets compared with the levels observed in mice fed standard (23%) or higher protein isocaloric diets. BCKAD subunit protein levels under these conditions changed co-ordinately even though the changes in RNA were not co-ordinate. The effects of hormonal changes that might be associated with these dietary changes were examined, using the rodent hepatoma cell line H4IIEC3. In these cells, the levels of E1 alpha protein and mRNA were significantly depressed in the presence of insulin. In contrast, the levels of E1 beta and E2 RNAs were not decreased by insulin. The half-lives of the E1 alpha and E2 RNAs were determined to be quite long, from 13 to 18 h, with insulin having no dramatic overall effect on the half-lives determined over 24 h. Therefore, it is likely that insulin directly affects the transcription of the E1 alpha gene rather than RNA stability in exerting its negative regulatory effect. This effect is specific to the E1 alpha subunit. The differences in BCKAD subunit RNA levels observed under various nutritional and developmental conditions may therefore be the result of the differential effects of insulin and other hormones on the multiple regulatory mechanisms modulating BCKAD subunit expression.
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Affiliation(s)
- P A Costeas
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore 21201, USA
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19
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van Hall G, MacLean DA, Saltin B, Wagenmakers AJ. Mechanisms of activation of muscle branched-chain alpha-keto acid dehydrogenase during exercise in man. J Physiol 1996; 494 ( Pt 3):899-905. [PMID: 8865084 PMCID: PMC1160687 DOI: 10.1113/jphysiol.1996.sp021542] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. Exercise leads to activation (dephosphorylation) of the branched-chain alpha-keto acid dehydrogenase (BCKADH). Here we investigate the effect of low pre-exercise muscle glycogen content and of branched-chain amino acid (BCAA) ingestion on the activity of BCKADH at rest and after 90 min of one-leg knee-extensor exercise at 65% maximal one-leg power output in five subjects. 2. Pre-exercise BCAA ingestion (308 mg BCAAs (kg body wt)-1) caused an increased muscle BCAA uptake, a higher intramuscular BCAA concentration and activation of BCKADH both at rest (9 +/- 1 versus 25 +/- 5% for the control and BCAA test, respectively) and after exercise (27 +/- 4 versus 54 +/- 7%). 3. At rest the percentage active BCKADH was not different, 6 +/- 2% versus 5 +/- 1%, in the normal and low glycogen content leg (392 +/- 21 and 147 +/- 34 mumol glycosyl units (g dry muscle)-1, respectively). The post-exercise BCKADH activity was higher in the low (46 +/- 2%) than in the normal glycogen content leg (26 +/- 2%). 4. It is concluded that: (1) the mechanism of activation by BCAA ingestion probably involves an increase of the muscle BCAA concentration; (2) BCKADH activation caused by exercise and BCAA ingestion are additive; (3) low pre-exercise muscle glycogen content augments the exercise-induced BCKADH activation without an increase in muscle BCAA concentration; and (4) the mechanism of BCKADH activation via BCAA ingestion and low muscle glycogen content are different.
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Affiliation(s)
- G van Hall
- Department of Human Biology, University of Limburg, Maastricht, The Netherlands.
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20
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Shimomura Y, Fujii H, Suzuki M, Murakami T, Fujitsuka N, Nakai N. Branched-chain alpha-keto acid dehydrogenase complex in rat skeletal muscle: regulation of the activity and gene expression by nutrition and physical exercise. J Nutr 1995; 125:1762S-1765S. [PMID: 7782942 DOI: 10.1007/978-3-0348-8981-0_13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023] Open
Abstract
Branched-chain alpha-keto acid dehydrogenase complex is the rate-limiting enzyme in the catabolism of branched-chain amino acids in skeletal muscle. It is suggested that activation of this enzyme in the muscle during exercise plays an important role in the increased oxidation of branched-chain amino acids in the muscle. Evidence suggests that branched-chain alpha-keto acids, the substrates for the enzyme, regulate the activity state of the enzyme in the muscle during exercise through phosphorylation/dephosphorylation cycle of the enzyme protein. We propose a model for the mechanism of enzyme activation by exercise. In addition to this acute effect of exercise, we present evidence suggesting that exercise training modulates the enzyme activity and gene expression for the enzyme. Increases in the total activity as well as enzyme proteins by exercise training are suggested to be associated with mitochondrial biogenesis in the muscle.
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Affiliation(s)
- Y Shimomura
- Department of Bioscience, Nagoya Institute of Technology, Japan
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21
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Ooiwa T, Goto H, Tsukamoto Y, Hayakawa T, Sugiyama S, Fujitsuka N, Shimomura Y. Regulation of valine catabolism in canine tissues: tissue distributions of branched-chain aminotransferase and 2-oxo acid dehydrogenase complex, methacrylyl-CoA hydratase and 3-hydroxyisobutyryl-CoA hydrolase. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1243:216-20. [PMID: 7873565 DOI: 10.1016/0304-4165(94)00061-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To clarify the valine catabolism, the activities of principal enzymes in its catabolic pathway, branched-chain aminotransferase, branched-chain 2-oxo acid dehydrogenase complex, methacrylyl-CoA hydratase and 3-hydroxyisobutyryl-CoA hydrolase, were measured using canine tissues. After killing of beagle dogs, tissues (liver, pancreas, kidney, heart, skeletal muscle and mucosae of digestive organs such as stomach, small intestine and colon) were removed and immediately frozen. Branched-chain aminotransferase activity in liver was the lowest among the tissues measured. In contrast, the activities of branched-chain 2-oxo acid dehydrogenase complex in liver as well as in kidney were relatively high and the enzyme complex activities were markedly low in small intestine and skeletal muscle. The activities of methacrylyl-CoA hydratase and 3-hydroxyisobutyryl-CoA hydrolase were relatively high in all tissues, suggesting that a cytotoxic intermediate, methacrylyl-CoA, is immediately degraded to non-toxic compounds, 3-hydroxyisobutyrate and free CoA. These findings suggest that the consumption of branched-chain amino acids in the absorption site (small intestine) is suppressed in order to supply them to the whole body, in particular to skeletal muscle and that skeletal muscle might act as a storage of gluconeogenic amino acids. The high capacity to dispose methacrylyl-CoA produced in the valine catabolism is suggested to play an important role in protecting cells against the toxic effects of methacrylyl-CoA.
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Affiliation(s)
- T Ooiwa
- Department of Internal Medicine II, Faculty of Medicine, University of Nagoya, Japan
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Zhao Y, Hawes J, Popov K, Jaskiewicz J, Shimomura Y, Crabb D, Harris R. Site-directed mutagenesis of phosphorylation sites of the branched chain alpha-ketoacid dehydrogenase complex. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32349-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Fujii H, Shimomura Y, Tokuyama K, Suzuki M. Modulation of branched-chain 2-oxo acid dehydrogenase complex activity in rat skeletal muscle by endurance training. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1199:130-6. [PMID: 8123661 DOI: 10.1016/0304-4165(94)90107-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Effects of endurance training and high-fat diet intake on the branched-chain 2-oxo acid dehydrogenase complex in skeletal muscle were examined in rats. The basal activities of the enzyme complex (approximately 4% in active form of the total enzyme) in the muscle of rats under the fed conditions were not different between trained and untrained rats. The basal activity in the muscle was elevated by 24 h starvation in both groups of rats, but the level of the elevation was significantly greater in the trained rats than in the untrained rats. On the other hand, high-fat diet intake did not alter the basal activity of the enzyme complex in the muscle or the profile of activation of the enzyme complex by muscle contractions elicited by the electrical stimulation, suggesting that the fat content in the diet does not affect the enzyme activity in the muscle. Neither training nor diet affected the total enzyme activity or the amount of enzyme protein. Activation by leucine administration of the enzyme complex in the muscle was greater in the trained rats than in the untrained rats, suggesting that the activity state of the enzyme complex is more responsive to regulation by the 2-oxo acid derived from leucine in the muscles of endurance-trained rats.
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Affiliation(s)
- H Fujii
- Laboratory of Biochemistry of Exercise and Nutrition, University of Tsukuba, Japan
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