Clinical and genetic spectrum of pyruvate dehydrogenase deficiency: Dihydrolipoamide acetyltransferase (E2) deficiency

Head, Rosie; Brown, Ruth; Zolkipli, Zarazuela; Shahdadpuri, Raveen; King, Mary D.; Clayton, Peter T.; Brown, Garry K.

doi:10.1002/ana.20550

Cited by 92 publications

(65 citation statements)

References 40 publications

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“…The membrane was incubated with a horseradish peroxidase (HRP)-conjugated bovine anti-mouse IgG-HRP or donkey anti-goat IgG-HRP (Santa Cruz Biotechnology), and the secondary antibody was detected using a chemiluminescence luminol reagent (Santa Cruz Biotechnology). For IP, patient fibroblast cells, control fibroblast cells, A431 cells and H69 cells were grown in 10-cm culture dishes or T-75 flask (H69 suspension cells) to about 90% confluence (ϳ10 6 of H69 cells). Because of the inherent instability of the E1␤ protein in the patient cells as well as in A431 cells, we divided the cells in two groups and either mock-treated them, or treated with MG132 (final concentration 20 M) overnight before they were harvested.…”

Section: Methodsmentioning

confidence: 99%

Pyruvate Dehydrogenase Complex Deficiency Caused by Ubiquitination and Proteasome-mediated Degradation of the E1β Subunit

Han¹,

Zhong²,

Srivastava

et al. 2008

Journal of Biological Chemistry

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Congenital deficiencies of the human pyruvate dehydrogenase (PDH) complex are considered to be due to loss of function mutations in one of the component enzymes. Here we describe a case of PDH deficiency associated with the PDH E1␤ subunit (PDHB) gene. The clinical phenotype of the patient was consistent with reported cases of PDH deficiency. Cultured skin fibroblasts demonstrated a 55% reduction in PDH activity and markedly decreased immunoreactivity for PDHB protein, compared with healthy controls. Surprisingly, nucleotide sequence analyses of cDNAs corresponding to the patient PDH E1␣ (PDHA1) and PDHB genes revealed no pathological mutations. Moreover, the relative expression level of PDHB mRNA and the rates of transcription and translation of the PDHB gene were normal. However, PDC activity could be restored in cells from this patient following treatment with MG132, a specific proteasome inhibitor, and normal levels of E1␤ could be detected in MG132-treated cells. Similar results were obtained following treatment with Tyrphostin 23 (Tyr23), a specific inhibitor of epidermal growth factor receptor-protein-tyrosine kinase (EGFR-PTK), which also restored E1␤ protein levels to those in cells from healthy subjects or from patients with PDHA1 deficiency. The index patient's cells contained a high basal level of EGFR-PTK activity that correlated with the high level of ubiquitination of cellular proteins, although the total EGFR protein levels were similar to those in cells from El␣-deficient subjects and healthy subjects. These data indicate that PDH deficiency in our patient involves a post-translational modification in which EGFR-PTK-mediated tyrosine phosphorylation of the E1␤ protein leads to enhanced ubiquitination followed by proteasome-mediated degradation. They also provide a novel mechanism accounting for congenital deficiency of the PDH complex and perhaps other inborn errors of metabolism.The nuclear encoded mitochondrial pyruvate dehydrogenase (PDH) 2 complex plays major roles in regulating cellular fuel metabolism, acid-base equilibrium and energetics (1, 2). The complex consists of three catalytic components: pyruvate dehydrogenase (E1; EC 1.2.4.1), dihydrolipoamide transacetylase (E2; EC 2.3.1.12), and dihydro-lipoamide dehydrogenase (E3; EC 1.8.1.4), and an additional protein known as the E3-binding protein (E3BP). Rapid post-translational regulation of the complex is mediated in large part by reversible phosphorylation of the ␣ subunit of E1 that is catalyzed by isoforms of PDH kinase and PDH phosphatase.The E1 enzyme (EC 1.2.4.1) is a heterotetrameric (␣ 2 ␤ 2 ) ␣-ketoacid decarboxylase that irreversibly oxidizes pyruvate to acetyl-CoA in the presence of thiamine pyrophosphate (TPP) and also catalyzes the subsequent reductive acetylation of the lipoyl moiety of E2. Most reported mutations of the PDH complex are located in the X-linked gene for the ␣ subunit of the E1 component (MIM 312170). Only a small number of patients have been described with mutations in the E2, E3, E3BP, or PDH phosphatase g...

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Section: Methodsmentioning

confidence: 99%

Pyruvate Dehydrogenase Complex Deficiency Caused by Ubiquitination and Proteasome-mediated Degradation of the E1β Subunit

Han¹,

Zhong²,

Srivastava

et al. 2008

Journal of Biological Chemistry

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“…The majority of defects occur in the E 1 and E3BP (E3-binding protein, also known as PDHX) components, with a smaller number of cases being reported for the E 1 , E2 and E3 components (Brown et al 2004;Cameron et al 2008;Head et al 2005;Lissens et al 2000;Robinson 2001). DeWciency of the PDH phosphatase was originally described on a biochemical basis in 1975 and 1979 for patients who showed low native PDHC activity compared with calcium-stimulated enzyme activity (DeVivo et al 1979;Robinson and Sherwood 1975).…”

Section: Introductionmentioning

confidence: 95%

Pyruvate dehydrogenase phosphatase 1 (PDP1) null mutation produces a lethal infantile phenotype

et al. 2009

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Pyruvate dehydrogenase phosphatase deficiency has previously only been confirmed at the molecular level in two brothers and two breeds of dog with exercise intolerance. A female patient, who died at 6 months, presented with lactic acidemia in the neonatal period with serum lactate levels ranging from 2.5 to 17 mM. Failure of dichloroacetate to activate the PDH complex in skin fibroblasts was evident, but not in early passages. A homozygous c.277G > T (p.E93X) nonsense mutation in the PDP1 gene was identified in genomic DNA and immunoblotting showed a complete absence of PDP1 protein in mitochondria. Native PDHC activity could be restored by the addition of either recombinant PDP1 or PDP2. This highlights the role of PDP2, the second phosphatase isoform, in PDP1-deficient patients for the first time. We conclude that the severity of the clinical course associated with PDP1 deficiency can be quite variable depending on the exact nature of the molecular defect.

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“…Differentiation of subunit defects has been achieved by enzymatic and immunoblot analyses. Later on defects of PDHC subunits have been identified on the genetic level (Endo et al 1989;Liu et al 1993;Aral et al 1997;Brown et al 2004;Head et al 2005). Recently, a number of genetic defects in either PDHC regulation (Maj et al 2005), mitochondrial pyruvate import (Bricker et al 2012) or in the metabolism of PDHC-relevant cofactors (Zeng et PODs are underestimated in the field of mitochondrial diseases due to several reasons: a) Not all diagnostic centres include biochemical investigations of PDHC in their routine programme.…”

Section: Introductionmentioning

confidence: 96%

The spectrum of pyruvate oxidation defects in the diagnosis of mitochondrial disorders

Sperl

Fleuren

Freisinger

et al. 2014

J of Inher Metab Disea

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Pyruvate oxidation defects (PODs) are among the most frequent causes of deficiencies in the mitochondrial energy metabolism and represent a substantial subset of classical mitochondrial diseases. PODs are not only caused by deficiency of subunits of the pyruvate dehydrogenase complex (PDHC) but also by various disorders recently described in the whole pyruvate oxidation route including cofactors, regulation of PDHC and the mitochondrial pyruvate carrier. Our own patients from 2000 to July 2014 and patients identified by a systematic survey of the literature from 1970 to July 2014 with a pyruvate oxidation disorder and a genetically proven defect were included in the study (n=628). Of these defects 74.2% (n=466) belong to PDHC subunits, 24.5% (n=154) to cofactors, 0.5% (n=3) to PDHC regulation and 0.8% (n=5) to mitochondrial pyruvate import. PODs are underestimated in the field of mitochondrial diseases because not all diagnostic centres include biochemical investigations of PDHC in their routine analysis. Cofactor and transport defects can be missed, if pyruvate oxidation is not measured in intact mitochondria routinely. Furthermore deficiency of the X-chromosomal PDHA1 can be biochemically missed depending on the X-inactivation pattern. This is reflected by an increasing number of patients diagnosed recently by genetic high throughput screening approaches. PDHC deficiency including regulation and import affect mainly the glucose dependent central and peripheral nervous system and skeletal muscle. PODs with combined enzyme defects affect also other organs like heart, lung and liver. The spectrum of clinical presentation of PODs is still expanding. PODs are a therapeutically interesting group of mitochondrial diseases since some can be bypassed by ketogenic diet or treated by cofactor supplementation. PDHC kinase inhibition, chaperone therapy and PGC1α stimulation is still a matter of further investigations.

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Clinical and genetic spectrum of pyruvate dehydrogenase deficiency: Dihydrolipoamide acetyltransferase (E2) deficiency

Cited by 92 publications

References 40 publications

Pyruvate Dehydrogenase Complex Deficiency Caused by Ubiquitination and Proteasome-mediated Degradation of the E1β Subunit

Pyruvate Dehydrogenase Complex Deficiency Caused by Ubiquitination and Proteasome-mediated Degradation of the E1β Subunit

Pyruvate dehydrogenase phosphatase 1 (PDP1) null mutation produces a lethal infantile phenotype

The spectrum of pyruvate oxidation defects in the diagnosis of mitochondrial disorders

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