Biochemical and genetic studies of four patients with pyruvate dehydrogenase E1α deficiency

Marsac, Cécile; Benelli, C; Desguerre, Isabelle; Diry, Monique; Fouque, Françoise; Meırleır, Linda De; Ponsot, G; Seneca, Sara; Poggi, F; Saudubray, Jean‐Marie; Zabot, M. T.; Fontan, D; Lissens, Willy

doi:10.1007/s004390050449

Cited by 47 publications

(40 citation statements)

References 49 publications

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“…None of the mutations that have been well defined as causing "thiamine-responsive" PDHC deficiency have involved amino acid residues that are directly involved in TPP binding; most are adjacent to the binding site and probably alter the position of the actual side chains that interact with the cofactor, weakening their binding. There are two groups of these: p. Ile87Met (present report), p.Arg88Ser (Marsac et al 1997), p.Arg88Cys (Fujii et al 2006) and p.Gly89Ser (Naito et al 1999) on one side and p.Phe205Leu (Naito et al 2002a), p.Met210Val (Tripatara et al 1999), p.Trp214 (Lissens et al 2000), p.Leu216Phe (Naito et al 2002a) and p. Pro217Leu (also denoted as Pro188Leu) (Hemalatha et al 1995) on the other. A number of patients have been reported as thiamine responsive but have mutations involving amino acid residues that are located well away from the TPP-binding site.…”

Section: Discussionmentioning

confidence: 56%

Thiamine-Responsive and Non-responsive Patients with PDHC-E1 Deficiency: A Retrospective Assessment

Dongen

Brown

et al. 2014

JIMD Reports

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Section: Discussionmentioning

confidence: 56%

Thiamine-Responsive and Non-responsive Patients with PDHC-E1 Deficiency: A Retrospective Assessment

Dongen

Brown

et al. 2014

JIMD Reports

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“…The clinical and immunoblot findings for patients 1 and 2 have been reported elsewhere (15). The studies were approved by local ethic committees and have been conducted with informed consent of the parents.…”

Section: Case Reportsmentioning

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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“…Most of the cases of this severe disease, which is responsible for early death in the majority of patients (3), are sporadic and result from a new mutation arising within the germ cells of one of the parents (11,30,34). The majority of the molecular defects of the PDH complex have been localized in the E1␣ subunit-encoding gene at chromosome Xp22.1 (gene symbol PDHA1; MIM 312170), and at least 75 different mutations in the coding region have been reported (31).…”

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confidence: 99%

The SR Protein SC35 Is Responsible for Aberrant Splicing of the E1α Pyruvate Dehydrogenase mRNA in a Case of Mental Retardation with Lactic Acidosis

Gabut

Miné²,

Marsac³

et al. 2005

Molecular and Cellular Biology

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Pyruvate dehydrogenase (PDH) complex deficiency is a major cause of lactic acidosis and Leigh's encephalomyelopathies in infancy and childhood, resulting in early death in the majority of patients. Most of the molecular defects have been localized in the coding regions of the E1␣ PDH gene. Recently, we identified a novel mutation of the E1␣ PDH gene in a patient with an encephalopathy and lactic acidosis. This mutation, located downstream of exon 7, activates a cryptic splice donor and leads to the retention of intronic sequences. Here, we demonstrate that the mutation results in an increased binding of the SR protein SC35. Consistently, ectopic overexpression of this splicing factor enhanced the use of the cryptic splice site, whereas small interfering RNA-mediated reduction of the SC35 protein levels in primary fibroblasts from the patient resulted in the almost complete disappearance of the aberrantly spliced E1␣ PDH mRNA. Our findings open the exciting prospect for a novel therapy of an inherited disease by altering the level of a specific splicing factor.Removal of intervening sequences (introns) from precursor messenger RNAs (pre-mRNA) is an essential step in the expression of most metazoan protein-encoding genes, often regulated in a cell-type-specific or developmental manner. Alternative splicing enables the same precursor to give rise to several mRNAs that code for proteins having distinct functions. Thus, the precise selection of 5Ј and 3Ј splicing sites is a way to generate diversity and may lead to the regulation of gene expression according to tissue type or during development of the organism. The results of a recently published genome-wide survey of human alternative pre-mRNA splicing with exon junction microarrays (22) indicate that at least 74% of human multiexon genes are alternatively spliced.Among the splicing factors involved in splice site choice, members of the SR protein family have been extensively studied (see references 18 and 33 for reviews). SR proteins are characterized by the presence of one or two copies of an RNA recognition motif and a carboxyl-terminal domain rich in arginine and serine residues (RS domain). The RS domain is responsible for specific protein-protein interactions between RS domain-containing proteins (25,(42)(43)(44), whereas the RNA recognition motif domain recognizes several classes of specific RNA motifs, including exonic splicing enhancers (ESEs) and intronic splicing enhancers. These sequences have been demonstrated to play a key role in both alternative and constitutive splice site selection (see references 2 and 41 for reviews). This activity is counteracted by that of splicing repressors, such as members of the hnRNP family which can bind RNA in a nonspecific way but also recognize negative regulatory elements known as exonic and intronic splicing silencers (see references 29 and 43 for reviews). Such an antagonism accounts for the ability of SR proteins to influence splice site choice in a concentration-dependent manner (28, 33).

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Biochemical and genetic studies of four patients with pyruvate dehydrogenase E1α deficiency

Cited by 47 publications

References 49 publications

Thiamine-Responsive and Non-responsive Patients with PDHC-E1 Deficiency: A Retrospective Assessment

Thiamine-Responsive and Non-responsive Patients with PDHC-E1 Deficiency: A Retrospective Assessment

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

The SR Protein SC35 Is Responsible for Aberrant Splicing of the E1α Pyruvate Dehydrogenase mRNA in a Case of Mental Retardation with Lactic Acidosis

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