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Li C, Yang Q, Zhang L. Identification of putative allosteric inhibitors of BCKDK via virtual screening and biological evaluation. J Enzyme Inhib Med Chem 2024; 39:2290458. [PMID: 38059302 DOI: 10.1080/14756366.2023.2290458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 11/21/2023] [Indexed: 12/08/2023] Open
Abstract
Abnormal accumulation of branched-chain amino acids (BCAAs) can lead to metabolic diseases and cancers. Branched-chain α-keto acid dehydrogenase kinase (BCKDK) is a key negative regulator of BCAA catabolism, and targeting BCKDK provides a promising therapeutic approach for diseases caused by BCAA accumulation. Here, we screened PPHN and POAB as novel putative allosteric inhibitors by integrating allosteric binding site prediction, large-scale ligand database virtual screening, and bioactivity evaluation assays. Both of them showed a high binding affinity to BCKDK, with Kd values of 3.9 μM and 1.86 μM, respectively. In vivo experiments, the inhibitors demonstrated superior kinase inhibitory activity and notable antiproliferative and proapoptotic effects on diverse cancer cells. Finally, bulk RNA-seq analysis revealed that PPHN and POAB suppressed cell growth through a range of signalling pathways. Taken together, our findings highlight two novel BCKDK inhibitors as potent therapeutic candidates for metabolic diseases and cancers associated with BCAA dysfunctional metabolism.
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Affiliation(s)
- Chunqiong Li
- Genomics Center, Chinese Institute for Brain Research, Beijing, China
| | - Quanjun Yang
- Department of Pharmacy, Shanghai Sixth People's Hospital Affiliated Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Li Zhang
- Genomics Center, Chinese Institute for Brain Research, Beijing, China
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Gotvaldová K, Špačková J, Novotný J, Baslarová K, Ježek P, Rossmeislová L, Gojda J, Smolková K. BCAA metabolism in pancreatic cancer affects lipid balance by regulating fatty acid import into mitochondria. Cancer Metab 2024; 12:10. [PMID: 38532464 DOI: 10.1186/s40170-024-00335-5] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 03/07/2024] [Indexed: 03/28/2024] Open
Abstract
BACKGROUND Pancreatic ductal adenocarcinoma (PDAC) has been associated with the host dysmetabolism of branched-chain amino acids (BCAAs), however, the implications for the role of BCAA metabolism in PDAC development or progression are not clear. The mitochondrial catabolism of valine, leucine, and isoleucine is a multistep process leading to the production of short-chain R-CoA species. They can be subsequently exported from mitochondria as short-chain carnitines (SC-CARs), utilized in anabolic pathways, or released from the cells. METHODS We examined the specificities of BCAA catabolism and cellular adaptation strategies to BCAA starvation in PDAC cells in vitro. We used metabolomics and lipidomics to quantify major metabolic changes in response to BCAA withdrawal. Using confocal microscopy and flow cytometry we quantified the fluorescence of BODIPY probe and the level of lipid droplets (LDs). We used BODIPY-conjugated palmitate to evaluate transport of fatty acids (FAs) into mitochondria. Also, we have developed a protocol for quantification of SC-CARs, BCAA-derived metabolites. RESULTS Using metabolic profiling, we found that BCAA starvation leads to massive triglyceride (TG) synthesis and LD accumulation. This was associated with the suppression of activated FA transport into the mitochondrial matrix. The suppression of FA import into mitochondria was rescued with the inhibitor of the acetyl-CoA carboxylase (ACC) and the activator of AMP kinase (AMPK), which both regulate carnitine palmitoyltransferase 1A (CPT1) activation status. CONCLUSIONS Our data suggest that BCAA catabolism is required for the import of long chain carnitines (LC-CARs) into mitochondria, whereas the disruption of this link results in the redirection of activated FAs into TG synthesis and its deposition into LDs. We propose that this mechanism protects cells against mitochondrial overload with LC-CARs and it might be part of the universal reaction to amino acid perturbations during cancer growth, regulating FA handling and storage.
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Affiliation(s)
- Klára Gotvaldová
- Institute of Physiology of the Czech Academy of Sciences, Laboratory of Mitochondrial Physiology, Vídeňská 1083, 142 20, Prague 4 - Krč, Czech Republic
| | - Jitka Špačková
- Institute of Physiology of the Czech Academy of Sciences, Laboratory of Mitochondrial Physiology, Vídeňská 1083, 142 20, Prague 4 - Krč, Czech Republic
| | - Jiří Novotný
- Institute of Physiology of the Czech Academy of Sciences, Laboratory of Mitochondrial Physiology, Vídeňská 1083, 142 20, Prague 4 - Krč, Czech Republic
| | - Kamila Baslarová
- Institute of Physiology of the Czech Academy of Sciences, Laboratory of Mitochondrial Physiology, Vídeňská 1083, 142 20, Prague 4 - Krč, Czech Republic
- First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Petr Ježek
- Institute of Physiology of the Czech Academy of Sciences, Laboratory of Mitochondrial Physiology, Vídeňská 1083, 142 20, Prague 4 - Krč, Czech Republic
| | - Lenka Rossmeislová
- Department of Pathophysiology, Center for Research on Nutrition, Metabolism, and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czech Republic
- Third Faculty of Medicine, Franco-Czech Laboratory for Clinical Research on Obesity, Prague, Czech Republic
| | - Jan Gojda
- Third Faculty of Medicine, Franco-Czech Laboratory for Clinical Research on Obesity, Prague, Czech Republic
- Department of Internal Medicine, Královské Vinohrady University Hospital and Third Faculty of Medicine, Prague, Czech Republic
| | - Katarína Smolková
- Institute of Physiology of the Czech Academy of Sciences, Laboratory of Mitochondrial Physiology, Vídeňská 1083, 142 20, Prague 4 - Krč, Czech Republic.
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3
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Han L, Dong L, Leung K, Zhao Z, Li Y, Gao L, Chen Z, Xue J, Qing Y, Li W, Pokharel SP, Gao M, Chen M, Shen C, Tan B, Small A, Wang K, Zhang Z, Qin X, Yang L, Wunderlich M, Zhang B, Mulloy JC, Marcucci G, Chen CW, Wei M, Su R, Chen J, Deng X. METTL16 drives leukemogenesis and leukemia stem cell self-renewal by reprogramming BCAA metabolism. Cell Stem Cell 2023; 30:52-68.e13. [PMID: 36608679 PMCID: PMC9838187 DOI: 10.1016/j.stem.2022.12.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 11/01/2022] [Accepted: 12/06/2022] [Indexed: 01/07/2023]
Abstract
N6-methyladenosine (m6A), the most prevalent internal modification in mammalian mRNAs, is involved in many pathological processes. METTL16 is a recently identified m6A methyltransferase. However, its role in leukemia has yet to be investigated. Here, we show that METTL16 is a highly essential gene for the survival of acute myeloid leukemia (AML) cells via CRISPR-Cas9 screening and experimental validation. METTL16 is aberrantly overexpressed in human AML cells, especially in leukemia stem cells (LSCs) and leukemia-initiating cells (LICs). Genetic depletion of METTL16 dramatically suppresses AML initiation/development and maintenance and significantly attenuates LSC/LIC self-renewal, while moderately influencing normal hematopoiesis in mice. Mechanistically, METTL16 exerts its oncogenic role by promoting expression of branched-chain amino acid (BCAA) transaminase 1 (BCAT1) and BCAT2 in an m6A-dependent manner and reprogramming BCAA metabolism in AML. Collectively, our results characterize the METTL16/m6A/BCAT1-2/BCAA axis in leukemogenesis and highlight the essential role of METTL16-mediated m6A epitranscriptome and BCAA metabolism reprograming in leukemogenesis and LSC/LIC maintenance.
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Affiliation(s)
- Li Han
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, China
| | - Lei Dong
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Keith Leung
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Zhicong Zhao
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Department of Liver Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Yangchan Li
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Department of Radiation Oncology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Lei Gao
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Zhenhua Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Jianhuang Xue
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Ying Qing
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Wei Li
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Sheela Pangeni Pokharel
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Min Gao
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; School of Pharmaceutical Sciences, Jiangnan University, Wuxi 214122, China
| | - Meiling Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; Department of Hematology, Fujian Provincial Key Laboratory of Hematology, Fujian Institute of Hematology, Fujian Medical University Union Hospital, Fuzhou, Fujian 350001, China
| | - Chao Shen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Brandon Tan
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Andrew Small
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Kitty Wang
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Zheng Zhang
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Xi Qin
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Lu Yang
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA
| | - Mark Wunderlich
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Bin Zhang
- City of Hope Comprehensive Cancer Center and Gehr Family Center for Leukemia Research, City of Hope, Duarte, CA 91010, USA; Department of Hematologic Malignancies Translational Science, City of Hope, Monrovia, CA 91016, USA
| | - James C Mulloy
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Guido Marcucci
- City of Hope Comprehensive Cancer Center and Gehr Family Center for Leukemia Research, City of Hope, Duarte, CA 91010, USA; Department of Hematologic Malignancies Translational Science, City of Hope, Monrovia, CA 91016, USA
| | - Chun-Wei Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; City of Hope Comprehensive Cancer Center and Gehr Family Center for Leukemia Research, City of Hope, Duarte, CA 91010, USA
| | - Minjie Wei
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, China.
| | - Rui Su
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA.
| | - Jianjun Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA; City of Hope Comprehensive Cancer Center and Gehr Family Center for Leukemia Research, City of Hope, Duarte, CA 91010, USA.
| | - Xiaolan Deng
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA 91016, USA.
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Rossmeislová L, Gojda J, Smolková K. Pancreatic cancer: branched-chain amino acids as putative key metabolic regulators? Cancer Metastasis Rev 2021; 40:1115-1139. [PMID: 34962613 DOI: 10.1007/s10555-021-10016-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/18/2021] [Indexed: 02/06/2023]
Abstract
Branched-chain amino acids (BCAA) are essential amino acids utilized in anabolic and catabolic metabolism. While extensively studied in obesity and diabetes, recent evidence suggests an important role for BCAA metabolism in cancer. Elevated plasma levels of BCAA are associated with an increased risk of developing pancreatic cancer, namely pancreatic ductal adenocarcinoma (PDAC), a tumor with one of the highest 1-year mortality rates. The dreadful prognosis for PDAC patients could be attributable also to the early and frequent development of cancer cachexia, a fatal host metabolic reprogramming leading to muscle and adipose wasting. We propose that BCAA dysmetabolism is a unifying component of several pathological conditions, i.e., obesity, insulin resistance, and PDAC. These conditions are mutually dependent since PDAC ranks among cancers tightly associated with obesity and insulin resistance. It is also well-established that PDAC itself can trigger insulin resistance and new-onset diabetes. However, the exact link between BCAA metabolism, development of PDAC, and tissue wasting is still unclear. Although tissue-specific intracellular and systemic metabolism of BCAA is being intensively studied, unresolved questions related to PDAC and cancer cachexia remain, namely, whether elevated circulating BCAA contribute to PDAC etiology, what is the biological background of BCAA elevation, and what is the role of adipose tissue relative to BCAA metabolism during cancer cachexia. To cover those issues, we provide our view on BCAA metabolism at the intracellular, tissue, and whole-body level, with special emphasis on different metabolic links to BCAA intermediates and the role of insulin in substrate handling.
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Affiliation(s)
- Lenka Rossmeislová
- Department of Pathophysiology, Center for Research On Nutrition, Metabolism, and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czech Republic
- Franco-Czech Laboratory for Clinical Research On Obesity, Third Faculty of Medicine, Prague, Czech Republic
| | - Jan Gojda
- Franco-Czech Laboratory for Clinical Research On Obesity, Third Faculty of Medicine, Prague, Czech Republic
- Department of Internal Medicine, Královské Vinohrady University Hospital and Third Faculty of Medicine, Prague, Czech Republic
| | - Katarína Smolková
- Laboratory of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
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Biswas D, Tozer K, Dao KT, Perez LJ, Mercer A, Brown A, Hossain I, Yip AM, Aguiar C, Motawea H, Brunt KR, Shea J, Legare JF, Hassan A, Kienesberger PC, Pulinilkunnil T. Adverse Outcomes in Obese Cardiac Surgery Patients Correlates With Altered Branched-Chain Amino Acid Catabolism in Adipose Tissue and Heart. Front Endocrinol (Lausanne) 2020; 11:534. [PMID: 32903728 PMCID: PMC7438793 DOI: 10.3389/fendo.2020.00534] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/30/2020] [Indexed: 12/22/2022] Open
Abstract
Background: Predicting relapses of post-operative complications in obese patients who undergo cardiac surgery is significantly complicated by persistent metabolic maladaptation associated with obesity. Despite studies supporting the linkages of increased systemic branched-chain amino acids (BCAAs) driving the pathogenesis of obesity, metabolome wide studies have either supported or challenged association of circulating BCAAs with cardiovascular diseases (CVDs). Objective: We interrogated whether BCAA catabolic changes precipitated by obesity in the heart and adipose tissue can be reliable prognosticators of adverse outcomes following cardiac surgery. Our study specifically clarified the correlation between BCAA catabolizing enzymes, cellular BCAAs and branched-chain keto acids (BCKAs) with the severity of cardiometabolic outcomes in obese patients pre and post cardiac surgery. Methods: Male and female patients of ages between 44 and 75 were stratified across different body mass index (BMI) (non-obese = 17, pre-obese = 19, obese class I = 14, class II = 17, class III = 12) and blood, atrial appendage (AA), and subcutaneous adipose tissue (SAT) collected during cardiac surgery. Plasma and intracellular BCAAs and BC ketoacids (BCKAs), tissue mRNA and protein expression and activity of BCAA catabolizing enzymes were assessed and correlated with clinical parameters. Results: Intramyocellular, but not systemic, BCAAs increased with BMI in cardiac surgery patients. In SAT, from class III obese patients, mRNA and protein expression of BCAA catabolic enzymes and BCKA dehydrogenase (BCKDH) enzyme activity was decreased. Within AA, a concomitant increase in mRNA levels of BCAA metabolizing enzymes was observed, independent of changes in BCKDH protein expression or activity. BMI, indices of tissue dysfunction and duration of hospital stay following surgery correlated with BCAA metabolizing enzyme expression and metabolite levels in AA and SAT. Conclusion: This study proposes that in a setting of obesity, dysregulated BCAA catabolism could be an effective surrogate to determine cardiac surgery outcomes and plausibly predict premature re-hospitalization.
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Affiliation(s)
- Dipsikha Biswas
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
- IMPART Investigator Team Canada, Saint John, NB, Canada
| | - Kathleen Tozer
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
| | - Khoi T. Dao
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
| | - Lester J. Perez
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
| | - Angella Mercer
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
- IMPART Investigator Team Canada, Saint John, NB, Canada
| | - Amy Brown
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
| | - Intekhab Hossain
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
| | - Alexandra M. Yip
- New Brunswick Heart Centre, Saint John Regional Hospital, Saint John, NB, Canada
| | - Christie Aguiar
- IMPART Investigator Team Canada, Saint John, NB, Canada
- New Brunswick Heart Centre, Saint John Regional Hospital, Saint John, NB, Canada
| | - Hany Motawea
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
- IMPART Investigator Team Canada, Saint John, NB, Canada
| | - Keith R. Brunt
- IMPART Investigator Team Canada, Saint John, NB, Canada
- Department of Pharmacology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
| | - Jennifer Shea
- Department of Pathology, Dalhousie University, Saint John, NB, Canada
- Department of Laboratory Medicine, Saint John Regional Hospital, Saint John, NB, Canada
| | - Jean F. Legare
- IMPART Investigator Team Canada, Saint John, NB, Canada
- New Brunswick Heart Centre, Saint John Regional Hospital, Saint John, NB, Canada
| | - Ansar Hassan
- IMPART Investigator Team Canada, Saint John, NB, Canada
- New Brunswick Heart Centre, Saint John Regional Hospital, Saint John, NB, Canada
| | - Petra C. Kienesberger
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
- IMPART Investigator Team Canada, Saint John, NB, Canada
| | - Thomas Pulinilkunnil
- Department of Biochemistry and Molecular Biology, Dalhousie University, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
- IMPART Investigator Team Canada, Saint John, NB, Canada
- *Correspondence: Thomas Pulinilkunnil
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Edhager AV, Povlsen JA, Løfgren B, Bøtker HE, Palmfeldt J. Proteomics of the Rat Myocardium during Development of Type 2 Diabetes Mellitus Reveals Progressive Alterations in Major Metabolic Pathways. J Proteome Res 2018; 17:2521-2532. [PMID: 29847139 DOI: 10.1021/acs.jproteome.8b00276] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [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: 12/31/2022]
Abstract
Congestive heart failure and poor clinical outcome after myocardial infarction are known complications in patients with type-2 diabetes mellitus (T2DM). Protein alterations may be involved in the mechanisms underlying these disarrays in the diabetic heart. Here we map proteins involved in intracellular metabolic pathways in the Zucker diabetic fatty rat heart as T2DM develops using MS based proteomics. The prediabetic state only induced minor pathway changes, whereas onset and late T2DM caused pronounced perturbations. Two actin-associated proteins, ARPC2 and TPM3, were up-regulated at the prediabetic state indicating increased actin dynamics. All differentially regulated proteins involved in fatty acid metabolism, both peroxisomal and mitochondrial, were up-regulated at late T2DM, whereas enzymes of branched chain amino acid degradation were all down-regulated. At both onset and late T2DM, two members of the serine protease inhibitor superfamily, SERPINA3K and SERPINA3L, were down-regulated. Furthermore, we found alterations in proteins involved in clearance of advanced glycation end-products and lipotoxicity, DCXR and CBR1, at both onset and late T2DM. These proteins deserve elucidation with regard to their role in T2DM pathogenesis and their respective role in the deterioration of the diabetic heart. Data are available via ProteomeXchange with identifiers PXD009538, PXD009554, and PXD009555.
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Affiliation(s)
- Anders Valdemar Edhager
- Research Unit for Molecular Medicine, Department of Clinical Medicine , Aarhus University and Aarhus University Hospital , 8200 , Aarhus N , Denmark
| | | | - Bo Løfgren
- Department of Cardiology , Aarhus University Hospital , 8200 , Aarhus N , Denmark.,Institute for Experimental Clinical Research , Aarhus University , 8000 , Aarhus C , Denmark
| | - Hans Erik Bøtker
- Department of Cardiology , Aarhus University Hospital , 8200 , Aarhus N , Denmark
| | - Johan Palmfeldt
- Research Unit for Molecular Medicine, Department of Clinical Medicine , Aarhus University and Aarhus University Hospital , 8200 , Aarhus N , Denmark
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Ananieva EA, Van Horn CG, Jones MR, Hutson SM. Liver BCATm transgenic mouse model reveals the important role of the liver in maintaining BCAA homeostasis. J Nutr Biochem 2017; 40:132-40. [PMID: 27886623 DOI: 10.1016/j.jnutbio.2016.10.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 10/19/2016] [Accepted: 10/25/2016] [Indexed: 01/08/2023]
Abstract
Unlike other amino acids, the branched-chain amino acids (BCAAs) largely bypass first-pass liver degradation due to a lack of hepatocyte expression of the mitochondrial branched-chain aminotransferase (BCATm). This sets up interorgan shuttling of BCAAs and liver-skeletal muscle cooperation in BCAA catabolism. To explore whether complete liver catabolism of BCAAs may impact BCAA shuttling in peripheral tissues, the BCATm gene was stably introduced into mouse liver. Two transgenic mouse lines with low and high hepatocyte expression of the BCATm transgene (LivTg-LE and LivTg-HE) were created and used to measure liver and plasma amino acid concentrations and determine whether the first two BCAA enzymatic steps in liver, skeletal muscle, heart and kidney were impacted. Expression of the hepatic BCATm transgene lowered the concentrations of hepatic BCAAs while enhancing the concentrations of some nonessential amino acids. Extrahepatic BCAA metabolic enzymes and plasma amino acids were largely unaffected, and no growth rate or body composition differences were observed in the transgenic animals as compared to wild-type mice. Feeding the transgenic animals a high-fat diet did not reverse the effect of the BCATm transgene on the hepatic BCAA catabolism, nor did the high-fat diet cause elevation in plasma BCAAs. However, the high-fat-diet-fed BCATm transgenic animals experienced attenuation in the mammalian target of rapamycin (mTOR) pathway in the liver and had impaired blood glucose tolerance. These results suggest that complete liver BCAA metabolism influences the regulation of glucose utilization during diet-induced obesity.
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