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Liang Z, Ralph-Epps T, Schmidtke MW, Lazcano P, Denis SW, Balážová M, Teixeira J NDR, Chakkour M, Hazime S, Ren M, Schlame M, Houtkooper RH, Greenberg ML. Upregulation of the AMPK-FOXO1-PDK4 pathway is a primary mechanism of pyruvate dehydrogenase activity reduction in tafazzin-deficient cells. Sci Rep 2024; 14:11497. [PMID: 38769106 PMCID: PMC11106297 DOI: 10.1038/s41598-024-62262-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 05/15/2024] [Indexed: 05/22/2024] Open
Abstract
Barth syndrome (BTHS) is a rare disorder caused by mutations in the TAFAZZIN gene. Previous studies from both patients and model systems have established metabolic dysregulation as a core component of BTHS pathology. In particular, features such as lactic acidosis, pyruvate dehydrogenase (PDH) deficiency, and aberrant fatty acid and glucose oxidation have been identified. However, the lack of a mechanistic understanding of what causes these conditions in the context of BTHS remains a significant knowledge gap, and this has hindered the development of effective therapeutic strategies for treating the associated metabolic problems. In the current study, we utilized tafazzin-knockout C2C12 mouse myoblasts (TAZ-KO) and cardiac and skeletal muscle tissue from tafazzin-knockout mice to identify an upstream mechanism underlying impaired PDH activity in BTHS. This mechanism centers around robust upregulation of pyruvate dehydrogenase kinase 4 (PDK4), resulting from hyperactivation of AMP-activated protein kinase (AMPK) and subsequent transcriptional upregulation by forkhead box protein O1 (FOXO1). Upregulation of PDK4 in tafazzin-deficient cells causes direct phospho-inhibition of PDH activity accompanied by increased glucose uptake and elevated intracellular glucose concentration. Collectively, our findings provide a novel mechanistic framework whereby impaired tafazzin function ultimately results in robust PDK4 upregulation, leading to impaired PDH activity and likely linked to dysregulated metabolic substrate utilization. This mechanism may underlie previously reported findings of BTHS-associated metabolic dysregulation.
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Affiliation(s)
- Zhuqing Liang
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Tyler Ralph-Epps
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | | | - Pablo Lazcano
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Simone W Denis
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Gastroenterology Endocrinology and Metabolism Institute, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Institute, Amsterdam, The Netherlands
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, The Netherlands
| | - Mária Balážová
- Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 84005, Bratislava, Slovakia
| | | | - Mohamed Chakkour
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Sanaa Hazime
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Mindong Ren
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, Grossman School of Medicine, New York University, New York, NY, USA
| | - Michael Schlame
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, Grossman School of Medicine, New York University, New York, NY, USA
| | - Riekelt H Houtkooper
- Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Gastroenterology Endocrinology and Metabolism Institute, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences Institute, Amsterdam, The Netherlands
- Emma Center for Personalized Medicine, Amsterdam UMC, Amsterdam, The Netherlands
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA.
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Liang Z, Ralph-Epps T, Schmidtke MW, Kumar V, Greenberg ML. Decreased pyruvate dehydrogenase activity in Tafazzin-deficient cells is caused by dysregulation of pyruvate dehydrogenase phosphatase 1 (PDP1). J Biol Chem 2024; 300:105697. [PMID: 38301889 PMCID: PMC10884759 DOI: 10.1016/j.jbc.2024.105697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/13/2024] [Accepted: 01/19/2024] [Indexed: 02/03/2024] Open
Abstract
Cardiolipin (CL), the signature lipid of the mitochondrial inner membrane, is critical for maintaining optimal mitochondrial function and bioenergetics. Disruption of CL metabolism, caused by mutations in the CL remodeling enzyme TAFAZZIN, results in the life-threatening disorder Barth syndrome (BTHS). While the clinical manifestations of BTHS, such as dilated cardiomyopathy and skeletal myopathy, point to defects in mitochondrial bioenergetics, the disorder is also characterized by broad metabolic dysregulation, including abnormal levels of metabolites associated with the tricarboxylic acid (TCA) cycle. Recent studies have identified the inhibition of pyruvate dehydrogenase (PDH), the gatekeeper enzyme for TCA cycle carbon influx, as a key deficiency in various BTHS model systems. However, the molecular mechanisms linking aberrant CL remodeling, particularly the primary, direct consequence of reduced tetralinoleoyl-CL (TLCL) levels, to PDH activity deficiency are not yet understood. In the current study, we found that remodeled TLCL promotes PDH function by directly binding to and enhancing the activity of PDH phosphatase 1 (PDP1). This is supported by our findings that TLCL uniquely activates PDH in a dose-dependent manner, TLCL binds to PDP1 in vitro, TLCL-mediated PDH activation is attenuated in the presence of phosphatase inhibitor, and PDP1 activity is decreased in Tafazzin-knockout (TAZ-KO) C2C12 myoblasts. Additionally, we observed decreased mitochondrial calcium levels in TAZ-KO cells and treating TAZ-KO cells with calcium lactate (CaLac) increases mitochondrial calcium and restores PDH activity and mitochondrial oxygen consumption rate. Based on our findings, we conclude that reduced mitochondrial calcium levels and decreased binding of PDP1 to TLCL contribute to decreased PDP1 activity in TAZ-KO cells.
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Affiliation(s)
- Zhuqing Liang
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Tyler Ralph-Epps
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Michael W Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Vikalp Kumar
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA.
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Ralph-Epps T, Onu CJ, Vo L, Schmidtke MW, Le A, Greenberg ML. Studying Lipid-Related Pathophysiology Using the Yeast Model. Front Physiol 2021; 12:768411. [PMID: 34777024 PMCID: PMC8581491 DOI: 10.3389/fphys.2021.768411] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/04/2021] [Indexed: 01/01/2023] Open
Abstract
Saccharomyces cerevisiae, commonly known as baker's yeast, is one of the most comprehensively studied model organisms in science. Yeast has been used to study a wide variety of human diseases, and the yeast model system has proved to be an especially amenable tool for the study of lipids and lipid-related pathophysiologies, a topic that has gained considerable attention in recent years. This review focuses on how yeast has contributed to our understanding of the mitochondrial phospholipid cardiolipin (CL) and its role in Barth syndrome (BTHS), a genetic disorder characterized by partial or complete loss of function of the CL remodeling enzyme tafazzin. Defective tafazzin causes perturbation of CL metabolism, resulting in many downstream cellular consequences and clinical pathologies that are discussed herein. The influence of yeast research in the lipid-related pathophysiologies of Alzheimer's and Parkinson's diseases is also summarized.
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Affiliation(s)
- Tyler Ralph-Epps
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - Chisom J Onu
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - Linh Vo
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - Michael W Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - Anh Le
- Muskegon Catholic Central High School, Muskegon, MI, United States
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
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