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Jennings EA, Abi-Rached ZH, Jones DE, Ryan RO. 3-Methylglutarylcarnitine: A biomarker of mitochondrial dysfunction. Clin Chim Acta 2023; 551:117629. [PMID: 37935273 PMCID: PMC10872575 DOI: 10.1016/j.cca.2023.117629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 11/09/2023]
Abstract
The acylcarnitines comprise a wide range of acyl groups linked via an ester bond to the hydroxyl group of L-carnitine. Mass spectrometry methods are capable of measuring the relative abundance of hundreds of acylcarnitines in a single drop of blood. As such, acylcarnitines can serve as sensitive biomarkers of disease. For certain acylcarnitines, however, their biochemical origin, and biomedical significance, remain unclear. One such example is 3-methylglutaryl (3MG) carnitine (C5-3M-DC). Whereas 3MG carnitine levels are normally very low, elevated levels are detected in discrete inborn errors of metabolism (IEM) as well as different forms of heart disease. Moreover, acute injury, including γ radiation exposure, paraquat poisoning, and traumatic brain injury manifest elevated levels of 3MG carnitine in blood and/or urine. Recent evidence indicates that two distinct biosynthetic routes to 3MG carnitine exist. The first, caused by an inherited deficiency in the leucine catabolism pathway enzyme, 3-hydroxy-3-methylglutaryl (HMG) CoA lyase, leads to a buildup of trans-3-methylglutaconyl (3MGC) CoA. Reduction of the double bond in trans-3MGC CoA generates 3MG CoA, which is then converted to 3MG carnitine by carnitine acyltransferase. This route, however, cannot explain why 3MG carnitine levels increase in IEMs that do not affect leucine metabolism or various chronic and acute disease states. In these cases, disease-related defects in aerobic energy metabolism result in diversion of acetyl CoA to trans-3MGC CoA. Once formed, trans-3MGC CoA is reduced to 3MG CoA and esterified to form 3MG carnitine. Thus, 3MG carnitine, represents a potential biomarker of disease processes associated with compromised mitochondrial energy metabolism.
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Affiliation(s)
- Elizabeth A Jennings
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States
| | - Zane H Abi-Rached
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States
| | - Dylan E Jones
- Department of Physical & Environmental Sciences Colorado Mesa University, Grand Junction, CO 81501, United States
| | - Robert O Ryan
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States.
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Jones DE, Romenskaia I, Kosma DK, Ryan RO. Role of non-enzymatic chemical reactions in 3-methylglutaconic aciduria. FEBS J 2022; 289:2948-2958. [PMID: 34877790 PMCID: PMC9117401 DOI: 10.1111/febs.16316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/13/2021] [Accepted: 12/07/2021] [Indexed: 11/28/2022]
Abstract
3-Methylglutaconic (3MGC) aciduria occurs in numerous inborn errors associated with compromised mitochondrial energy metabolism. In these disorders, 3MGC CoA is produced de novo from acetyl CoA in three steps with the final reaction catalysed by 3MGC CoA hydratase (AUH). In in vitro assays, whereas recombinant AUH dehydrated 3-hydroxy-3-methylglutaryl (HMG) CoA to 3MGC CoA, free CoA was also produced. Although HMG CoA is known to undergo non-enzymatic intramolecular cyclisation, forming HMG anhydride and free CoA, the amount of free CoA generated increased when AUH was present. To test the hypothesis that the AUH-dependent increase in CoA production is caused by intramolecular cyclisation of 3MGC CoA, gas chromatography-mass spectrometry analysis of organic acids was performed. In the absence of AUH, HMG CoA was converted to HMG acid while, in the presence of AUH, 3MGC acid was also detected. To determine which 3MGC acid diastereomer was formed, immunoblot assays were conducted with 3MGCylated BSA. In competition experiments, when α-3MGC IgG was preincubated with trans-3MGC acid or cis-3MGC acid, the cis diastereomer inhibited antibody binding to 3MGCylated BSA. When an AUH assay product mix served as competitor, α-3MGC IgG binding to 3MGCylated BSA was also inhibited, indicating cis-3MGC acid is produced in incubations of AUH and HMG CoA. Thus, non-enzymatic isomerisation of trans-3MGC CoA drives AUH-dependent HMG CoA dehydration and explains the occurrence of cis-3MGC acid in urine of subjects with 3MGC aciduria. Furthermore, the ability of cis-3MGC anhydride to non-enzymatically acylate protein substrates may have deleterious pathophysiological consequences.
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Affiliation(s)
- Dylan E. Jones
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557
| | - Irina Romenskaia
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557
| | - Dylan K. Kosma
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557
| | - Robert O. Ryan
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557
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Jones DE, Jennings EA, Ryan RO. Diversion of Acetyl CoA to 3-Methylglutaconic Acid Caused by Discrete Inborn Errors of Metabolism. Metabolites 2022; 12:metabo12050377. [PMID: 35629880 PMCID: PMC9146172 DOI: 10.3390/metabo12050377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 04/15/2022] [Accepted: 04/18/2022] [Indexed: 11/16/2022] Open
Abstract
A growing number of inborn errors of metabolism (IEM) have been identified that manifest 3-methylglutaconic (3MGC) aciduria as a phenotypic feature. In primary 3MGC aciduria, IEM-dependent deficiencies in leucine pathway enzymes prevent catabolism of trans-3MGC CoA. Consequently, this metabolite is converted to 3MGC acid and excreted in urine. In secondary 3MGC aciduria, however, no leucine metabolism pathway enzyme deficiencies exist. These IEMs affect mitochondrial membrane structure, electron transport chain function or ATP synthase subunits. As a result, acetyl CoA oxidation via the TCA cycle slows and acetyl CoA is diverted to trans-3MGC CoA, and then to 3MGC acid. Whereas the trans diastereomer of 3MGC CoA is the only biologically relevant diastereomer, the urine of affected subjects contains both cis- and trans-3MGC acids. Studies have revealed that trans-3MGC CoA is susceptible to isomerization to cis-3MGC CoA. Once formed, cis-3MGC CoA undergoes intramolecular cyclization, forming an anhydride that, upon hydrolysis, yields cis-3MGC acid. Alternatively, cis-3MGC anhydride can acylate protein lysine side chains. Once formed, cis-3MGCylated proteins can be deacylated by the NAD+-dependent enzyme, sirtuin 4. Taken together, the excretion of 3MGC acid in secondary 3MGC aciduria represents a barometer of defective mitochondrial function.
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Lodato V, Parlapiano G, Calì F, Silvetti MS, Adorisio R, Armando M, El Hachem M, Romanzo A, Dionisi-Vici C, Digilio MC, Novelli A, Drago F, Raponi M, Baban A. Cardiomyopathies in Children and Systemic Disorders When Is It Useful to Look beyond the Heart? J Cardiovasc Dev Dis 2022; 9:47. [PMID: 35200700 PMCID: PMC8877723 DOI: 10.3390/jcdd9020047] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 11/16/2022] Open
Abstract
Cardiomyopathy (CMP) is a rare disease in the pediatric population, with a high risk of morbidity and mortality. The genetic etiology of CMPs in children is extremely heterogenous. These two factors play a major role in the difficulties of establishing standard diagnostic and therapeutic protocols. Isolated CMP in children is a frequent finding, mainly caused by sarcomeric gene variants with a detection rate that can reach up to 50% of analyzed cohorts. Complex multisystemic forms of pediatric CMP are even more heterogenous. Few studies in literature take into consideration this topic as the main core since it represents a rarity (systemic CMP) within a rarity (pediatric population CMP). Identifying etiology in this cohort is essential for understanding prognosis, risk stratification, eligibility to heart transplantation and/or mechanical-assisted procedures, preventing multiorgan complications, and relatives' recurrence risk calculation. The previous points represent a cornerstone in patients' empowerment and personalized medical care approach. The aim of this work is to propose a new approach for an algorithm in the setting of the diagnostic framework of systemic pediatric CMP. On the other hand, during the literature review, we noticed a relatively common etiologic pattern in some forms of complex/multisystem CMP. In other words, certain syndromes such as Danon, Vici, Alström, Barth, and Myhre syndrome share a common pathway of directly or indirectly defective "autophagy" process, which appears to be a possible initiating/triggering factor for CMPs. This conjoint aspect could be important for possible prognostic/therapeutic implications in this category of patients. However, multicentric studies detailed functional and experimental models are needed prior to deriving conclusions.
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Affiliation(s)
- Valentina Lodato
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy; (V.L.); (G.P.); (F.C.); (M.S.S.); (F.D.)
| | - Giovanni Parlapiano
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy; (V.L.); (G.P.); (F.C.); (M.S.S.); (F.D.)
- Laboratory of Medical Genetics, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - Federica Calì
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy; (V.L.); (G.P.); (F.C.); (M.S.S.); (F.D.)
| | - Massimo Stefano Silvetti
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy; (V.L.); (G.P.); (F.C.); (M.S.S.); (F.D.)
| | - Rachele Adorisio
- Heart Failure Clinic-Heart Failure, Heart Transplant, Mechanical Circulatory Support Unit, Department of Pediatric Cardiology and Cardiac Surgery, Heart and Lung Transplant, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - Michela Armando
- Department of Neuroscience and Neurorehabilitation, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - May El Hachem
- Dermatology and Genodermatosis Units, Genetics and Rare Disease Research Division, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - Antonino Romanzo
- Ophtalmology Unit, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - Carlo Dionisi-Vici
- Division of Metabolism, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - Maria Cristina Digilio
- Genetics and Rare Diseases Research Division, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - Antonio Novelli
- Laboratory of Medical Genetics, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy;
| | - Fabrizio Drago
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy; (V.L.); (G.P.); (F.C.); (M.S.S.); (F.D.)
| | - Massimiliano Raponi
- Medical Direction, Bambino Gesù Children Hospital, IRCCS, 00165 Rome, Italy;
| | - Anwar Baban
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, IRCCS, 00165 Rome, Italy; (V.L.); (G.P.); (F.C.); (M.S.S.); (F.D.)
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Jones DE, Klacking E, Ryan RO. Inborn errors of metabolism associated with 3-methylglutaconic aciduria. Clin Chim Acta 2021; 522:96-104. [PMID: 34411555 PMCID: PMC8464523 DOI: 10.1016/j.cca.2021.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/11/2021] [Accepted: 08/13/2021] [Indexed: 11/22/2022]
Abstract
A growing number of inborn errors of metabolism (IEM) associated with compromised mitochondrial energy metabolism manifest an unusual phenotypic feature: 3-methylglutaconic (3MGC) aciduria. Two major categories of 3MGC aciduria, primary and secondary, have been described. In primary 3MGC aciduria, IEMs in 3MGC CoA hydratase (AUH) or HMG CoA lyase block leucine catabolism, resulting in a buildup of pathway intermediates, including 3MGC CoA. Subsequent thioester hydrolysis yields 3MGC acid, which is excreted in urine. In secondary 3MGC aciduria, no deficiencies in leucine catabolism enzymes exist and 3MGC CoA is formed de novo from acetyl CoA. In the "acetyl CoA diversion pathway", when IEMs directly, or indirectly, interfere with TCA cycle activity, acetyl CoA accumulates in the matrix space. This leads to condensation of two acetyl CoA to form acetoacetyl CoA, followed by another condensation between acetyl CoA and acetoacetyl CoA to form 3-hydroxy, 3-methylglutaryl (HMG) CoA. Once formed, HMG CoA serves as a substrate for AUH, producing trans-3MGC CoA. Non enzymatic isomerization of trans-3MGC CoA to cis-3MGC CoA precedes intramolecular cyclization to cis-3MGC anhydride plus CoA. Subsequent hydrolysis of cis-3MGC anhydride gives rise to cis-3MGC acid, which is excreted in urine. In reviewing 20 discrete IEMs that manifest secondary 3MGC aciduria, evidence supporting the acetyl CoA diversion pathway was obtained. This biochemical pathway serves as an "overflow valve" in muscle / brain tissue to redirect acetyl CoA to 3MGC CoA when entry to the TCA cycle is impeded.
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Affiliation(s)
- Dylan E Jones
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States
| | - Emma Klacking
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States
| | - Robert O Ryan
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States.
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6
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Jones DE, Ricker JD, Geary LM, Kosma DK, Ryan RO. Isomerization of trans-3-methylglutaconic acid. JIMD Rep 2021; 58:61-69. [PMID: 33728248 PMCID: PMC7932859 DOI: 10.1002/jmd2.12185] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/08/2020] [Accepted: 11/03/2020] [Indexed: 12/22/2022] Open
Abstract
3-Methylglutaconic (3MGC) aciduria is a common phenotypic feature of a growing number of inborn errors of metabolism. "Primary" 3MGC aciduria is caused by deficiencies in leucine pathway enzymes while "secondary" 3MGC aciduria results from inborn errors of metabolism that impact mitochondrial energy production. The metabolic precursor of 3MGC acid is trans-3MGC CoA, an intermediate in the leucine catabolism pathway. Gas chromatography-mass spectrometry (GC-MS) analysis of commercially available trans-3MGC acid yielded a mixture of cis and trans isomers while 1H-NMR spectroscopy of trans-3MGC acid at 25°C provided no evidence for the cis isomer. When trans-3MGC acid was incubated under conditions used for sample derivatization prior to GC-MS (but with no trimethylsilane added), 1H-NMR spectroscopy provided evidence of trans to cis isomerization. Incubation of trans-3MGC acid at 37°C resulted in time-dependent isomerization to cis-3MGC acid. Cis-3MGC acid behaved in a similar manner except that, under identical incubation conditions, less isomerization occurred. In agreement with these experimental results, molecular modeling studies provided evidence that the energy minimized structure of cis-3MGC acid is 4 kJ/mol more stable than that for trans-3MGC acid. Once generated in vivo, trans-3MGC acid is proposed to isomerize via a mechanism involving π electron delocalization with formation of a resonance structure that permits bond rotation. The data presented are consistent with the occurrence of both diastereomers in urine samples of subjects with 3MGC aciduria.
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Affiliation(s)
- Dylan E. Jones
- Department of Biochemistry and Molecular BiologyUniversity of Nevada RenoRenoNevadaUSA
| | - J. David Ricker
- Department of ChemistryUniversity of Nevada RenoRenoNevadaUSA
| | - Laina M. Geary
- Department of ChemistryUniversity of Nevada RenoRenoNevadaUSA
| | - Dylan K. Kosma
- Department of Biochemistry and Molecular BiologyUniversity of Nevada RenoRenoNevadaUSA
| | - Robert O. Ryan
- Department of Biochemistry and Molecular BiologyUniversity of Nevada RenoRenoNevadaUSA
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Young R, Jones DE, Diacovich L, Witkowski A, Ryan RO. trans-3-Methylglutaconyl CoA isomerization-dependent protein acylation. Biochem Biophys Res Commun 2021; 534:261-265. [PMID: 33280817 PMCID: PMC7785636 DOI: 10.1016/j.bbrc.2020.11.100] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 11/26/2022]
Abstract
3-methylglutaconic (3MGC) aciduria is associated with a growing number of discrete inborn errors of metabolism. Herein, an antibody-based approach to detection/quantitation of 3MGC acid has been pursued. When trans-3MGC acid conjugated keyhole limpet hemocyanin (KLH) was inoculated into rabbits a strong immune response was elicited. Western blot analysis provided evidence that immune serum, but not pre-immune serum, recognized 3MGC-conjugated bovine serum albumin (BSA). In competition ELISAs using isolated immune IgG, the limit of detection for free trans-3MGC acid was compared to that for cis-3MGC acid and four structurally related short-chain dicarboxylic acids. Surprisingly, cis-3MGC acid yielded a much lower limit of detection (∼0.1 mg/ml) than trans-3MGC acid (∼1.0 mg/ml) while all other dicarboxylic acids tested were poor competitors. The data suggest trans-3MGC- isomerized during, or after, conjugation to KLH such that the immunogen was actually comprised of KLH harboring a mixture of cis- and trans-3MGC haptens. To investigate this unexpected isomerization reaction, trans-3MGC CoA was prepared and incubated at 37 °C in the presence of BSA. Evidence was obtained that non-enzymatic isomerization of trans-3MGC CoA to cis-3MGC CoA precedes intramolecular catalysis to form cis-3MGC anhydride plus CoASH. Anhydride-dependent acylation of BSA generated 3MGCylated BSA, as detected by anti-3MGC immunoblot. The results presented provide an explanation for the unanticipated detection of 3MGCylated proteins in a murine model of primary 3MGC aciduria. Furthermore, non-enzymatic hydrolysis of cis-3MGC anhydride represents a potential source of cis-3MGC acid found in urine of subjects with 3MGC aciduria.
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Affiliation(s)
- Rebecca Young
- Department of Biochemistry and Molecular Biology, Mail Stop 0330, 1664 N. Virginia Street, University of Nevada, Reno, NV, 89557, USA
| | - Dylan E Jones
- Department of Biochemistry and Molecular Biology, Mail Stop 0330, 1664 N. Virginia Street, University of Nevada, Reno, NV, 89557, USA
| | - Lautaro Diacovich
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Andrzej Witkowski
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA, 94609, USA
| | - Robert O Ryan
- Department of Biochemistry and Molecular Biology, Mail Stop 0330, 1664 N. Virginia Street, University of Nevada, Reno, NV, 89557, USA.
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Jones DE, Perez L, Ryan RO. 3-Methylglutaric acid in energy metabolism. Clin Chim Acta 2019; 502:233-239. [PMID: 31730811 DOI: 10.1016/j.cca.2019.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/01/2019] [Accepted: 11/04/2019] [Indexed: 12/16/2022]
Abstract
3-methylglutaric (3MG) acid is a conspicuous C6 dicarboxylic organic acid classically associated with two distinct leucine pathway enzyme deficiencies. 3MG acid is excreted in urine of individuals harboring deficiencies in 3-hydroxy-3-methylglutaryl (HMG) CoA lyase (HMGCL) or 3-methylglutaconyl CoA hydratase (AUH). Whereas 3MG CoA is not part of the leucine catabolic pathway, it is likely formed via a side reaction involving reduction of the α-ß trans double bond in the leucine pathway intermediate, 3-methylglutaconyl CoA. While the metabolic basis for the accumulation of 3MG acid in subjects with deficiencies in HMGCL or AUH is apparent, the occurrence of 3MG aciduria in a host of unrelated inborn errors of metabolism associated with compromised mitochondrial energy metabolism is less clear. Herein, a novel mitochondrial biosynthetic pathway termed "the acetyl CoA diversion pathway", provides an explanation. The pathway is initiated by defective electron transport chain function which, ultimately, inhibits acetyl CoA entry into the TCA cycle. When this occurs, 3MG acid is synthesized in five steps from acetyl CoA via a novel reaction sequence, providing a metabolic rationale for the connection between 3MG aciduria and compromised mitochondrial energy metabolism.
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Affiliation(s)
- Dylan E Jones
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States
| | - Leanne Perez
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States
| | - Robert O Ryan
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, United States.
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Vamecq J, Papegay B, Nuyens V, Boogaerts J, Leo O, Kruys V. Mitochondrial dysfunction, AMPK activation and peroxisomal metabolism: A coherent scenario for non-canonical 3-methylglutaconic acidurias. Biochimie 2019; 168:53-82. [PMID: 31626852 DOI: 10.1016/j.biochi.2019.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 10/10/2019] [Indexed: 12/13/2022]
Abstract
The occurrence of 3-methylglutaconic aciduria (3-MGA) is a well understood phenomenon in leucine oxidation and ketogenesis disorders (primary 3-MGAs). In contrast, its genesis in non-canonical (secondary) 3-MGAs, a growing-up group of disorders encompassing more than a dozen of inherited metabolic diseases, is a mystery still remaining unresolved for three decades. To puzzle out this anthologic problem of metabolism, three clues were considered: (i) the variety of disorders suggests a common cellular target at the cross-road of metabolic and signaling pathways, (ii) the response to leucine loading test only discriminative for primary but not secondary 3-MGAs suggests these latter are disorders of extramitochondrial HMG-CoA metabolism as also attested by their failure to increase 3-hydroxyisovalerate, a mitochondrial metabolite accumulating only in primary 3-MGAs, (iii) the peroxisome is an extramitochondrial site possessing its own pool and displaying metabolism of HMG-CoA, suggesting its possible involvement in producing extramitochondrial 3-methylglutaconate (3-MG). Following these clues provides a unifying common basis to non-canonical 3-MGAs: constitutive mitochondrial dysfunction induces AMPK activation which, by inhibiting early steps in cholesterol and fatty acid syntheses, pipelines cytoplasmic acetyl-CoA to peroxisomes where a rise in HMG-CoA followed by local dehydration and hydrolysis may lead to 3-MGA yield. Additional contributors are considered, notably for 3-MGAs associated with hyperammonemia, and to a lesser extent in CLPB deficiency. Metabolic and signaling itineraries followed by the proposed scenario are essentially sketched, being provided with compelling evidence from the literature coming in their support.
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Affiliation(s)
- Joseph Vamecq
- Inserm, CHU Lille, Univ Lille, Department of Biochemistry and Molecular Biology, Laboratory of Hormonology, Metabolism-Nutrition & Oncology (HMNO), Center of Biology and Pathology (CBP) Pierre-Marie Degand, CHRU Lille, EA 7364 RADEME, University of North France, Lille, France.
| | - Bérengère Papegay
- Laboratory of Experimental Medicine (ULB unit 222), University Hospital Center, Charleroi, (CHU Charleroi), Belgium
| | - Vincent Nuyens
- Laboratory of Experimental Medicine (ULB unit 222), University Hospital Center, Charleroi, (CHU Charleroi), Belgium
| | - Jean Boogaerts
- Laboratory of Experimental Medicine (ULB unit 222), University Hospital Center, Charleroi, (CHU Charleroi), Belgium
| | - Oberdan Leo
- Laboratory of Immunobiology, Department of Molecular Biology, ULB Immunology Research Center (UIRC), Free University of Brussels (ULB), Gosselies, Belgium
| | - Véronique Kruys
- Laboratory of Molecular Biology of the Gene, Department of Molecular Biology, ULB Immunology Research Center (UIRC), Free University of Brussels (ULB), Gosselies, Belgium
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Snanoudj S, Mordel P, Dupas Q, Schanen C, Arion A, Gérard M, Read M, Nait Rabah D, Goux D, Chapon F, Jokic M, Allouche S. Identification of a novel splice site mutation in the SERAC1 gene responsible for the MEGDHEL syndrome. Mol Genet Genomic Med 2019; 7:e815. [PMID: 31251474 PMCID: PMC6687635 DOI: 10.1002/mgg3.815] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/12/2019] [Accepted: 05/16/2019] [Indexed: 11/22/2022] Open
Abstract
Background MEGDHEL is an autosomal recessive syndrome defined as 3‐MEthylGlutaconic aciduria (3‐MGA) with Deafness, Hepatopathy, Encephalopathy, and Leigh‐like syndrome on magnetic resonance imaging, due to mutations in the SERAC1 (Serine Active Site Containing 1) gene, which plays a role in the mitochondrial cardiolipin metabolism. Methods We report the case of a young patient who presented with a convulsive encephalopathy, 3‐methylglutaconic aciduria, deafness, and bilateral T2 hypersignals of the putamen and the thalami, who passed away at 8 years of age. Results Analysis of nuclear genes using an ampliSeq™ targeted custom panel disclosed two compound heterozygous variants in the SERAC1 gene: a nonsense substitution in exon 4, c.202C>T, resulting in a premature stop codon (p.Arg68*), and a novel variant at a canonical splicing site upstream exon 4 (c.129‐1G>C). mRNAs sequencing from the fibroblasts of the patient showed that the splice site variant resulted in exon 3 skipping without frameshift while Western blot experiments showed the absence of SERAC1 expression compared to controls and abnormal filipin staining. Conclusion We showed that the loss of the putative transmembrane domain of SERAC1, due to a novel splice site variant, impairs the protein expression and is responsible for the MEGDHEL syndrome.
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Affiliation(s)
- Sarah Snanoudj
- Departments of BiochemistryUniversity Hospital of CaenCaenFrance
- Department of Medical geneticsUniversity Hospital of CaenCaenFrance
| | - Patrick Mordel
- Department of Signalisation, Électrophysiologie et Imagerie des Lésions d'Ischémie‐Reperfusion MyocardiqueNormandie Univ, UNICAENCaenFrance
| | - Quentin Dupas
- Department of Signalisation, Électrophysiologie et Imagerie des Lésions d'Ischémie‐Reperfusion MyocardiqueNormandie Univ, UNICAENCaenFrance
| | - Cécile Schanen
- Departments of BiochemistryUniversity Hospital of CaenCaenFrance
| | - Alina Arion
- Department of Medical pediatricsUniversity Hospital of CaenCaenFrance
| | - Marion Gérard
- Department of Medical geneticsUniversity Hospital of CaenCaenFrance
| | | | | | - Didier Goux
- CmaBio3, SF 4206 ICORE, Normandie Univ, UNICAENCaenFrance
| | | | - Mickael Jokic
- Department of Medico‐Surgical Pediatric Intensive Care UnitUniversity Hospital of CaenCaenFrance
| | - Stéphane Allouche
- Departments of BiochemistryUniversity Hospital of CaenCaenFrance
- Department of Signalisation, Électrophysiologie et Imagerie des Lésions d'Ischémie‐Reperfusion MyocardiqueNormandie Univ, UNICAENCaenFrance
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11
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Enzymes involved in branched-chain amino acid metabolism in humans. Amino Acids 2017; 49:1005-1028. [DOI: 10.1007/s00726-017-2412-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/15/2017] [Indexed: 12/27/2022]
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Ikon N, Ryan RO. On the origin of 3-methylglutaconic acid in disorders of mitochondrial energy metabolism. J Inherit Metab Dis 2016; 39:749-756. [PMID: 27091556 PMCID: PMC4988875 DOI: 10.1007/s10545-016-9933-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/17/2016] [Accepted: 03/31/2016] [Indexed: 01/06/2023]
Abstract
3-methylglutaconic acid (3MGA)-uria occurs in numerous inborn errors of metabolism (IEM) associated with compromised mitochondrial energy metabolism. This organic acid arises from thioester cleavage of 3-methylglutaconyl CoA (3MG CoA), an intermediate in leucine catabolism. In individuals harboring mutations in 3MG CoA hydratase (i.e., primary 3MGA-uria), dietary leucine is the source of 3MGA. In secondary 3MGA-uria, however, no leucine metabolism defects have been reported. While others have suggested 3MGA arises from aberrant isoprenoid shunting from cytosol to mitochondria, an alternative route posits that 3MG CoA arises in three steps from mitochondrial acetyl CoA. Support for this biosynthetic route in IEMs is seen by its regulated occurrence in microorganisms. The fungus, Ustilago maydis, the myxobacterium, Myxococcus xanthus and the marine cyanobacterium, Lyngbya majuscule, generate 3MG CoA (or acyl carrier protein derivative) in the biosynthesis of iron chelating siderophores, iso-odd chain fatty acids and polyketide/nonribosomal peptide products, respectively. The existence of this biosynthetic machinery in these organisms supports a model wherein, under conditions of mitochondrial dysfunction, accumulation of acetyl CoA in the inner mitochondrial space as a result of inefficient fuel utilization drives de novo synthesis of 3MG CoA. Since humans lack the downstream biosynthetic capability of the organisms mentioned above, as 3MG CoA levels rise, thioester hydrolysis yields 3MGA, which is excreted in urine as unspent fuel. Understanding the metabolic origins of 3MGA may increase its utility as a biomarker.
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Affiliation(s)
- Nikita Ikon
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA, 94609, USA
| | - Robert O Ryan
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA, 94609, USA.
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Experimental Evidence that 3-Methylglutaric Acid Disturbs Mitochondrial Function and Induced Oxidative Stress in Rat Brain Synaptosomes: New Converging Mechanisms. Neurochem Res 2016; 41:2619-2626. [DOI: 10.1007/s11064-016-1973-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/23/2016] [Accepted: 06/01/2016] [Indexed: 12/14/2022]
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