Arginine 302 mutations in the pyruvate dehydrogenase E1α subunit gene: Identification of further patients and in vitro demonstration of pathogenicity

Otero, Lucy J.; Brown, Ruth; Brown, Garry K.

doi:10.1002/(sici)1098-1004(1998)12:2<114::aid-humu6>3.0.co;2-#

Cited by 24 publications

(12 citation statements)

References 17 publications

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“…Considerable phenotypic and allelic heterogeneity has been observed for this defect. Previous studies have reported that a decrease in the stability of the E1 ␣ immunoreactive subunit may contribute to the expression of many E1 ␣ mutations (6, 7); very few studies to distinguish mutations that impair polypeptide stability from those impairing catalytic efficiency have been carried out to date (8).…”

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confidence: 99%

Differential Effect of DCA Treatment on the Pyruvate Dehydrogenase Complex in Patients with Severe PDHC Deficiency

et al. 2003

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Dichloroacetate (DCA) is a structural analog of pyruvate that has been recommended for the treatment of primary lactic acidemia, particularly in patients with pyruvate dehydrogenase (PDHC) deficiency. Recent reports have demonstrated that the response to DCA may depend on the type of molecular abnormality. In this study, we investigated the response to DCA in various PDHC-deficient cell lines and tried to determine the mechanism involved. The effect of chronic 3-d DCA treatment on PDHC activity was assessed in two PDHC-deficient cell lines, each with a different point mutation in the E1␣ subunit gene (R378C and R88C), and one cell line in which an 8-bp tandem repeat was deleted (W383 del). Only two (R378C and R88C) of the three PDHC-deficient cell lines with very low levels of PDHC activity and unstable polypeptides were sensitive to chronic DCA treatment. In these cell lines, DCA treatment resulted in an increase in PDHC activity by 125 and 70%, respectively, with concomitant increases of 121 and 130% in steady-state levels of immunoreactive E1␣. DCA treatment reduced the turnover of the E1␣ subunit in R378C and R88C mutant cells with no significant effect on the E1␤ subunit. Chronic DCA treatment significantly improved the metabolic function of PDHC in digitonin-permeabilized R378C and R88C fibroblasts. The occurrence of DCA-sensitive mutations suggests that DCA treatment is potentially useful as an adjuvant to ketogenic and vitamin treatment in PDHC-deficient patients. PDHC deficiency is a nuclear-encoded mitochondrial disorder and a major recognized cause of neonatal encephalopathies associated with primary lactic acidosis (1). This multienzyme complex plays an important role in the irreversible oxidative decarboxylation of pyruvate to acetyl-CoA. E1, one of the subunits of the complex, is a thiamine pyrophosphatedependent pyruvate decarboxylase. It is a tetramer composed of two ␣ and two ␤ subunits, the ␣ subunit containing the thiamine pyrophosphate binding sites. E2 is a dihydrolipoamide acetyl transferase. E3 is a dihydrolipoamide dehydrogenase, and E3BP or protein X mediates the interaction between E2 and E3. Two elements regulate the complex: an E1 kinase and a phospho-E1 phosphatase, which phosphorylate and dephosphorylate, respectively, three serine residues in the E1 ␣ subunit, resulting in the deactivation and activation, respectively, of the complex (2).Defects in the PDHC are frequently attributed to deficiencies in the E1 ␣ component (3), encoded by chromosome X (Xp22.1-22.2) (4, 5). Considerable phenotypic and allelic heterogeneity has been observed for this defect. Previous studies have reported that a decrease in the stability of the E1 ␣ immunoreactive subunit may contribute to the expression of many E1 ␣ mutations (6, 7); very few studies to distinguish mutations that impair polypeptide stability from those impairing catalytic efficiency have been carried out to date (8).DCA is a structural analog of pyruvate that has been recommended for the treatment of primary lactic acidemia, particular...

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Differential Effect of DCA Treatment on the Pyruvate Dehydrogenase Complex in Patients with Severe PDHC Deficiency

et al. 2003

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“…Studies performed by several investigators concluded that these mutations might disturb the protein efficiency in many different ways; R88S, R127W and R378C seem to play a role in E 1 stability [8,9,19], while R288H and R302H give raise to normal E1 protein but are devoid of activity [15,23]. In addition, other authors [11] studied by site-directed mutagenesis two different mutations at R263 residue, and concluded that they act by apparently different mechanisms.…”

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confidence: 99%

“…The amplification of the 11 individual exons of PDHA1 gene, with respective intron-exon boundaries, was performed using specific primers designed by us, based on those previously described (primers and polymerase chain reaction conditions available on request) [20,23].…”

Section: Western Immunoblottingmentioning

confidence: 99%

Pyruvate dehydrogenase deficiency: identification of a novel mutation in the PDHA1 gene which responds to amino acid supplementation

et al. 2008

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“…The normal and mutant constructs were transfected into a clone of SV40-transformed fibroblasts from a female patient with PDH E1α deficiency (Otero et al, 1998). This clone expresses a mutant PDH E1α subunit gene that results in complete deficiency of both the mRNA and protein product.…”

Section: Cloning and Expression Of The Mutant Pdh E1α Sequencementioning

confidence: 99%

A pathogenic glutamate-to-aspartate substitution (D296E) in the pyruvate dehydrogenase E1 subunit genePDHA1

et al. 2003

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In a patient with fatal neonatal lactic acidosis due t o pyruvate dehydrogenase deficiency, the only potential mutation detected was c.888C>G in PDHA1, the gene for the E1 α subunit of the complex. This would result in a substitution of glutamate for aspartate (D296E). Pathogenicity of this minor alteration i n amino acid sequence was demonstrated by expression studies. By comparing the mutant sequence with the known structures of the E1 components of pyruvate dehydrogenase and the closely related branched chain α-ketoacid dehydrogenase, an explanation for the profound consequences of the mutation can be proposed.

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Arginine 302 mutations in the pyruvate dehydrogenase E1α subunit gene: Identification of further patients and in vitro demonstration of pathogenicity

Cited by 24 publications

References 17 publications

Differential Effect of DCA Treatment on the Pyruvate Dehydrogenase Complex in Patients with Severe PDHC Deficiency

Differential Effect of DCA Treatment on the Pyruvate Dehydrogenase Complex in Patients with Severe PDHC Deficiency

Pyruvate dehydrogenase deficiency: identification of a novel mutation in the PDHA1 gene which responds to amino acid supplementation

A pathogenic glutamate-to-aspartate substitution (D296E) in the pyruvate dehydrogenase E1 subunit genePDHA1

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