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Ohl L, Kuhs A, Pluck R, Durham E, Noji M, Philip ND, Arany Z, Ahrens-Nicklas RC. Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency. Mol Genet Metab Rep 2024; 39:101091. [PMID: 38770403 PMCID: PMC11103483 DOI: 10.1016/j.ymgmr.2024.101091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 05/04/2024] [Accepted: 05/06/2024] [Indexed: 05/22/2024] Open
Abstract
Branched chain ketoacid dehydrogenase kinase (BCKDK) deficiency is a recently described inherited neurometabolic disorder of branched chain amino acid (BCAA) metabolism implying increased BCAA catabolism. It has been hypothesized that a severe reduction in systemic BCAA levels underlies the disease pathophysiology, and that BCAA supplementation may ameliorate disease phenotypes. To test this hypothesis, we characterized a recent mouse model of BCKDK deficiency and evaluated the efficacy of enteral BCAA supplementation in this model. Surprisingly, BCAA supplementation exacerbated neurodevelopmental deficits and did not correct biochemical abnormalities despite increasing systemic BCAA levels. These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology. In support of this conclusion, genetic re-regulation of BCAA catabolism, through Dbt haploinsufficiency, partially rescued biochemical and behavioral phenotypes in BCKDK deficient mice. Collectively, these data raise into question assumptions widely made about the pathophysiology of BCKDK insufficiency and suggest a novel approach to develop potential therapies for this disease.
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Affiliation(s)
- Laura Ohl
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- College of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Amanda Kuhs
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Ryan Pluck
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Emily Durham
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Michael Noji
- College of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nathan D. Philip
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Zoltan Arany
- Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Rebecca C. Ahrens-Nicklas
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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Singh E, Chi Y, Kopesky J, Zimmerman M, Urrutia R, Basel D, Schwoerer JS. Computational structural genomics and clinical evidence suggest BCKDK gain-of-function may cause a potentially asymptomatic maple syrup urine disease phenotype. JIMD Rep 2024; 65:144-155. [PMID: 38736638 PMCID: PMC11078707 DOI: 10.1002/jmd2.12419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 05/14/2024] Open
Abstract
Maple syrup urine disease (MSUD) is a disorder of branched-chain amino acid metabolism caused by a defect in the branched-chain α-ketoacid dehydrogenase (BCKD) complex (OMIM #248600). The hallmark presentation is encephalopathic crisis in neonates, but can also present with metabolic decompensation, developmental delays, and feeding difficulties. Biochemical evidence for MSUD includes elevated branched-chain amino acids (BCAA) and the pathognomonic presence of alloisoleucine. The BCKD complex contains several subunits associated with autosomal recessive MSUD, while its regulatory proteins have less well-defined disease associations. We report on two families with the same BCKDK variant (c.1115C>G (p.Thr372Arg)). Probands were detected on newborn screening and demonstrated biochemical evidence of MSUD. The variant was identified in reportedly asymptomatic parents and additional family members who had elevated BCAA and alloisoleucine, following an autosomal dominant pattern of inheritance. To better define the functional effect of the variant on the kinase, we completed molecular modeling using sequence-based (2D), structural-based (3D), and dynamic-based (4D) analyses. The BCKDK variant modeling indicated a gain-of-function which leads to impaired BCAA catabolism consistent with the biochemical evidence in this cohort. Combining the evidence gained from molecular modeling with the absence of metabolic decompensation in our patients and several adult family members, despite encountering stressors typically problematic in classic MSUD, we suggest that heterozygous gain-of-function variants in BCKDK may represent a novel biochemical phenotype of MSUD with a benign clinical course.
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Affiliation(s)
- Emily Singh
- Division of Genetics, Department of PediatricsMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Young‐In Chi
- Mellowes Center for Genomic Sciences and Precision MedicineMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Jessica Kopesky
- Department of Clinical NutritionChildren's WisconsinMilwaukeeWisconsinUSA
| | - Michael Zimmerman
- Mellowes Center for Genomic Sciences and Precision MedicineMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Raul Urrutia
- Mellowes Center for Genomic Sciences and Precision MedicineMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Donald Basel
- Division of Genetics, Department of PediatricsMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Jessica Scott Schwoerer
- Division of Genetics, Department of PediatricsMedical College of WisconsinMilwaukeeWisconsinUSA
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Ohl L, Kuhs A, Pluck R, Durham E, Noji M, Philip ND, Arany Z, Ahrens-Nicklas RC. Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.12.560929. [PMID: 37873402 PMCID: PMC10592755 DOI: 10.1101/2023.10.12.560929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Branched chain ketoacid dehydrogenase kinase (BCKDK) deficiency is a recently described inherited neurometabolic disorder of branched chain amino acid (BCAA) metabolism implying increased BCAA catabolism. It has been hypothesized that a severe reduction in systemic BCAA levels underlies the disease pathophysiology, and that BCAA supplementation may ameliorate disease phenotypes. To test this hypothesis, we characterized a recent mouse model of BCKDK deficiency and evaluated the efficacy of enteral BCAA supplementation in this model. Surprisingly, BCAA supplementation exacerbated neurodevelopmental deficits and did not correct biochemical abnormalities despite increasing systemic BCAA levels. These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology. In support of this conclusion, genetic re-regulation of BCAA catabolism, through Dbt haploinsufficiency, partially rescued biochemical and behavioral phenotypes in BCKDK deficient mice. Collectively, these data raise into question assumptions widely made about the pathophysiology of BCKDK insufficiency and suggest a novel approach to develop potential therapies for this disease.
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Vaseghi H, Akrami SM, Rashidi‐Nezhad A. The challenges in the interpretation of genetic variants detected by genomics techniques in patients with congenital anomalies. J Clin Lab Anal 2023; 37:e24967. [PMID: 37823350 PMCID: PMC10623530 DOI: 10.1002/jcla.24967] [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: 07/05/2023] [Revised: 08/28/2023] [Accepted: 09/16/2023] [Indexed: 10/13/2023] Open
Abstract
BACKGROUND Despite the efforts that have been made to standardize the interpretation of variants, in some cases, their pathogenicity remains vague and confusing, and sometimes their interpretation does not help clinicians to establish clinical correlation using genetic test results. This study aims to shed more lights on these challenging variants. METHODS In a clinical setting, the variants found from 81 array CGH and 79 whole exome sequencing (WES) in patients with congenital anomalies were interpreted based on American College of Medical Genetics and Genomics guidelines. RESULTS In this study, the interpretation of the disease-causing variants and the variants with uncertain clinical significance detected by WES was far more challenging than the variants detected by array CGH. The presence of unreported clinical symptoms, incomplete penetrance, variable expressivity, parents' reluctance to analyze segregation in the family, and the limitations of prenatal tests, were among the challenging factors in the interpretation of variants in this study. CONCLUSION A careful study of the pedigree and disease mode of inheritance, as well as a careful clinical examination of the carrier parents in diseases with autosomal dominant inheritance, are among the primary strategies for determining the clinical significance of the variants. Continued efforts to mitigate these challenges are needed to improve the interpretation of variants.
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Affiliation(s)
- Hajar Vaseghi
- Department of Medical Genetics, School of MedicineTehran University of Medical SciencesTehranIran
| | - Seyed Mohammad Akrami
- Department of Medical Genetics, School of MedicineTehran University of Medical SciencesTehranIran
| | - Ali Rashidi‐Nezhad
- Maternal, Fetal and Neonatal Research Center, Family Health Research InstituteTehran University of Medical SciencesTehranIran
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Liu S, Kormos BL, Knafels JD, Sahasrabudhe PV, Rosado A, Sommese RF, Reyes AR, Ward J, Roth Flach RJ, Wang X, Buzon LM, Reese MR, Bhattacharya SK, Omoto K, Filipski KJ. Structural studies identify angiotensin II receptor blocker-like compounds as branched-chain ketoacid dehydrogenase kinase inhibitors. J Biol Chem 2023; 299:102959. [PMID: 36717078 PMCID: PMC9976451 DOI: 10.1016/j.jbc.2023.102959] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 01/19/2023] [Accepted: 01/25/2023] [Indexed: 01/30/2023] Open
Abstract
The mammalian mitochondrial branched-chain ketoacid dehydrogenase (BCKD) complex is a multienzyme complex involved in the catabolism of branched-chain amino acids. BCKD is regulated by the BCKD kinase, or BCKDK, which binds to the E2 subunit of BCKD, phosphorylates its E1 subunit, and inhibits enzymatic activity. Inhibition of the BCKD complex results in increased levels of branched-chain amino acids and branched-chain ketoacids, and this buildup has been associated with heart failure, type 2 diabetes mellitus, and nonalcoholic fatty liver disease. To find BCKDK inhibitors for potential treatment of these diseases, we performed both NMR and virtual fragment screening and identified tetrazole-bearing fragments that bind BCKDK at multiple sites. Through structure-based virtual screening expanding from these fragments, the angiotensin receptor blocker class antihypertension drugs and angiotensin receptor blocker-like compounds were discovered to be potent BCKDK inhibitors, suggesting potential new avenues for heart failure treatment combining BCKDK inhibition and antihypertension.
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Affiliation(s)
- Shenping Liu
- Medicine Design, Pfizer Inc, Groton, Connecticut, USA.
| | | | | | | | - Amy Rosado
- Medicine Design, Pfizer Inc, Groton, Connecticut, USA
| | | | - Allan R Reyes
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, Massachusetts, USA
| | - Jessica Ward
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, Massachusetts, USA
| | | | - Xiaochun Wang
- Medicine Design, Pfizer Inc, Groton, Connecticut, USA
| | | | | | | | - Kiyoyuki Omoto
- Medicine Design, Pfizer Inc, Cambridge, Massachusetts, USA
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The role of branched chain amino acids metabolic disorders in tumorigenesis and progression. Biomed Pharmacother 2022; 153:113390. [DOI: 10.1016/j.biopha.2022.113390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/04/2022] [Accepted: 07/07/2022] [Indexed: 11/20/2022] Open
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