The pyruvate dehydrogenase complex (PDC) is an emerging target for the treatment of metabolic syndrome. To maintain a steady-state concentration of adenosine triphosphate during the feed-fast cycle, cells require efficient utilization of fatty acid and glucose, which is controlled by the PDC. The PDC converts pyruvate, coenzyme A (CoA), and oxidized nicotinamide adenine dinucleotide (NAD+) into acetyl-CoA, reduced form of nicotinamide adenine dinucleotide (NADH), and carbon dioxide. The activity of the PDC is up- and down-regulated by pyruvate dehydrogenase kinase and pyruvate dehydrogenase phosphatase, respectively. In addition, pyruvate is a key intermediate of glucose oxidation and an important precursor for the synthesis of glucose, glycerol, fatty acids, and nonessential amino acids.
Acetyl Coenzyme A ; Adenosine Triphosphate ; Amino Acids ; Carbon Dioxide ; Coenzyme A ; Diabetes Mellitus ; Fatty Acids ; Glucose ; Glycerol ; NAD ; Obesity* ; Oxidoreductases* ; Phosphotransferases* ; Pyruvate Dehydrogenase (Lipoamide)-Phosphatase ; Pyruvate Dehydrogenase Complex ; Pyruvic Acid*

Pyruvate dehydrogenase complex (PDHC) deficiency is mostly due to mutations in the X-linked E1alpha subunit gene (PDHA1). Some of the patients with PDHC deficiency showed clinical improvements with thiamine treatment. We report the results of biochemical and molecular analysis in a female patient with lactic acidemia. The PDHC activity was assayed at different concentrations of thiamine pyrophosphate (TPP). The PDHC activity showed null activity at low TPP concentration (1 x 10(-3) mM), but significantly increased at a high TPP concentration (1 mM). Sequencing analysis of PDHA1 gene of the patient revealed a substitution of cysteine for tyrosine at position 161 (Y161C). Thiamine treatment resulted in reduction of the patient's serum lactate concentration and dramatic clinical improvement. Biochemical, molecular, and clinical data suggest that this patient has a thiamine-responsive PDHC deficiency due to a novel mutation, Y161C. Therefore, to detect the thiamine responsiveness it is necessary to measure activities of PDHC not only at high but also at low concentration of TPP.
Thiamine Pyrophosphate/metabolism ; Thiamine/*therapeutic use ; Pyruvate Dehydrogenase Complex Deficiency Disease/drug therapy/*genetics ; Pyruvate Dehydrogenase (Lipoamide)/*genetics ; *Point Mutation ; Infant, Newborn ; Humans ; Female ; Cells, Cultured

OBJECTIVETo analyze the clinical characteristics and genetype of one children who had been diagnosed with pyruvate dehydrogenase complex deficiency.

METHODComprehensive analyses of this case were performed, including clinical symptoms, signs, biochemical examinations and therapeutic effects. The eleven exons and splicing areas of PDHA1 were amplified with genomic DNA from whole blood. And variations were investigated by sequencing the PCR product. The patient was diagnosed with pyruvate dehydrogenase complex deficiency by sequence analysis of PDHA1 gene.

RESULTThe patient was a 2 years and 4 monthes old boy. He presented with muscle hypotonia and weakness for one year, and experienced recurrent episodes of unstable head control, unable to sit by himself or stand without support, with persistently hyperlactacidemia. Metabolic testing revealed blood lactate 5.37 mmol/L, pyruvate 0.44 mmol/L, and lactate/pyruvate ratio was 12.23. MRI of the brain showed hyperintense signals on the T2 and T2 Flair weighted images in the basal ganglia bilaterally. Sequence analysis of PDHA1 gene showed a G>A point mutation at nucleotide 778, resulting in a substitution of glutarnine for arginine at position 263 (R263Q). And the diagnosis of pyruvate dehydrogenase complex deficiency was identified. By giving the therapy with ketogenic diet, vitamin B(1), coenzyme Q(10) and L-carnitine , the boy was in a stable condition.

CONCLUSIONThe severity and the clinical phenotypes of pyruvate dehydrogenase complex deficiency varied. Sequence analysis of PDHA1 gene revealed a 788G>A (R263Q) mutation. Patients who presented with unexplained muscle hypotonia, weakness and hyperlactacidemia could be diveded by gene analysis. And appropriate treatment can improve the quality of life.

Brain ; Carnitine ; Child, Preschool ; Exons ; genetics ; Humans ; Magnetic Resonance Imaging ; Male ; Mutation ; Phenotype ; Pyruvate Dehydrogenase (Lipoamide) ; genetics ; Pyruvate Dehydrogenase Complex Deficiency Disease ; diagnosis ; genetics ; Pyruvic Acid

OBJECTIVETo study the molecular genetic mechanism and genetic diagnosis of pyruvate dehydrogenase complex deficiency (PHD), and to provide a basis for genetic counseling and prenatal genetic diagnosis of PHD.

METHODSPolymerase chain reaction (PCR) was performed to amplify the 11 exons and exon junction of the PDHA1 gene from a child who was diagnosed with PHD based on clinical characteristics and laboratory examination results. The PCR products were sequenced to determine the mutation. An analysis of amino acid conservation and prediction of protein secondary and tertiary structure were performed using bioinformatic approaches to identify the pathogenicity of the novel mutation.

RESULTSOne novel duplication mutation, c.1111_1158dup48bp, was found in the exon 11 of the PDHA1 gene of the patient. No c.1111_1158dup48bp mutation was detected in the sequencing results from 50 normal controls. The results of protein secondary and tertiary structure prediction showed that the novel mutation c.1111 _1158dup48bp led to the duplication of 16 amino acids residues, serine371 to phenylalanine386, which induced a substantial change in protein secondary and tertiary structure. The conformational change was not detected in the normal controls.

CONCLUSIONSThe novel duplication mutation c.1111_1158dup48bp in the PDHA1 gene is not due to gene polymorphisms but a possible novel pathogenic mutation for PHD.

Amino Acid Sequence ; Humans ; Infant ; Male ; Molecular Sequence Data ; Mutation ; Protein Conformation ; Pyruvate Dehydrogenase (Lipoamide) ; chemistry ; genetics ; Pyruvate Dehydrogenase Complex Deficiency Disease ; genetics

OBJECTIVESTo construct the expression vector of the pyruvate dehydrogenase complex E2 subunit gene (PDC-E2).

METHODSThe PDC-E2 gene was amplified from human lymphocytes with RT-PCR, and was cloned into pExSecI vector to induce the PDC-E2 expression. The products were identified with western blot and ELISA.

RESULTSThe expression vector pExSecI/PDC-E2 was successfully constructed. The products could be identified by the specific self-antibodies in the sera from the primary biliary cirrhosis patients.

CONCLUSIONHigh efficient expression vector of PDC-E2 lays the foundation for serum assay of primary biliary cirrhosis patients with prokaryotic expressing PDC-E2.

Cloning, Molecular ; Dihydrolipoyllysine-Residue Acetyltransferase ; Enzyme-Linked Immunosorbent Assay ; Humans ; Liver Cirrhosis, Biliary ; blood ; diagnosis ; immunology ; Lymphocytes ; enzymology ; Polymerase Chain Reaction ; Pyruvate Dehydrogenase Complex ; analysis ; biosynthesis ; genetics

This review summarizes the recent developments on the regulation of human pyruvate dehydrogenase complex (PDC) by site-specific phosphorylation by four kinases. Mutagenic analysis of the three phosphorylation sites of human pyruvate dehydrogenase (E1) showed the site-independent mechanism of phosphorylation as well as site-independent dephosphorylation of the three phosphorylation sites and the importance of each phosphorylation site for the inactivation of E1. Both the negative charge and size of the group introduced at site 1 were involved in human E1 inactivation. Mechanism of inactivation of E1 was suggested to be site-specific. Phosphorylation of site 1 affected E1 interaction with the lipoyl domain of dihydrolipoamide acetyltransferase, whereas phosphorylation site 3 appeared to be closer to the thiamine pyrophosphate (TPP)-binding region affecting coenzyme interaction with human E1. Four isoenzymes of pyruvate dehydrogenase kinase (PDK) showed different specificity for the three phosphorylation sites of E1. All four PDKs phosphorylated sites 1 and 2 in PDC with different rates, and only PDK1 phosphorylated site 3. PDK2 was maximally stimulated by the reduction/acetylation of the lipoyl groups of E2. Presence of the multiple phosphorylation sites and isoenzymes of PDK is important for the tissue-specific regulation of PDC under different physiological conditions.
Acetylation ; Binding Sites ; Gene Expression Regulation, Enzymologic ; Human ; Isoenzymes/*metabolism ; Kinetics ; Mutagenesis, Site-Directed ; Mutation ; Oxidation-Reduction ; Phosphorylation ; Phosphotransferases/chemistry/genetics/*metabolism ; Protein Structure, Tertiary ; Pyruvate Dehydrogenase (Lipoamide)/metabolism ; Pyruvate Dehydrogenase Complex/chemistry/genetics/*metabolism ; Substrate Specificity ; Support, U.S. Gov't, P.H.S. ; Thiamine Pyrophosphate/metabolism

OBJECTIVETo identify autoepitopes of E2 subunit of pyruvate dehydrogenase complex (PDC-E2) specific CD8+ CTL in primary biliary cirrhosis (PBC) patients.

METHODSAn online database SYFPEITHI was applied to predict HLA-A*0201 restricted epitopes which located in PDC-E2 30-50 aa and 150-190 aa where B-cell epitopes clustered with CD4+ T-cell epitopes. T2 cell line reconstitution and stabilization assay, induction of specific CTL lines from peripheral blood mononuclear cells (PBMCs) of patients with PBC and cytotoxicity of peptides-induced CTL were performed to screen the epitopes from those candidates.

RESULTSFive potential epitopes were predicted by database. Of the 5 candidates, two peptides 159-167 aa and 165-174 aa, with highly binding activity to HLA-A*0201 molecules, could stimulate PBMCs from most HLA-A*0201 positive PBC patients to proliferate and peptide-induced CTL lines showed specific cytotoxicity.

CONCLUSIONPeptides of KLSEGDLLA (159-167 aa) and LLAEIETDKA (165-174 aa) in the inner lipoyl domain of PDC-E2 are HLA-A*0201 restricted CD8+ CTL immunodominant epitopes in PBC.

Antibody-Producing Cells ; cytology ; Autoantigens ; immunology ; Autoimmunity ; CD8-Positive T-Lymphocytes ; cytology ; immunology ; metabolism ; Cell Line ; Dihydrolipoyllysine-Residue Acetyltransferase ; Epitope Mapping ; Epitopes, T-Lymphocyte ; immunology ; HLA-A Antigens ; immunology ; HLA-A2 Antigen ; Humans ; Liver Cirrhosis, Biliary ; enzymology ; genetics ; immunology ; Phenotype ; Protein Binding ; Pyruvate Dehydrogenase Complex ; genetics ; immunology ; metabolism ; T-Lymphocytes, Cytotoxic ; immunology

Mitochondrial dysfunction represents a biochemically and clinically diverse group of conditions that can affect any organs with high energy requirement such as brain and muscle being particularly vulnerable. Pyruvate dehydrogenase complex (PDHC) deficiency is one type of mitochondrial dysfuntion that is anesthetically associated with lactic acidosis, muscle hypotonia, malignant hyperthermia, and postoperative respiratory failure. We report a case of general anesthetic management during ventriculoperitoneal shunt in a pediatric patient with PDHC deficiency and its possible considerations.
Acidosis, Lactic ; Brain ; Humans ; Malignant Hyperthermia ; Muscle Hypotonia ; Muscles ; Pyruvate Dehydrogenase Complex ; Pyruvic Acid ; Respiratory Insufficiency ; Ventriculoperitoneal Shunt

Mitochondrial dysfunction represents a biochemically and clinically diverse group of conditions that can affect any organs with high energy requirement such as brain and muscle being particularly vulnerable. Pyruvate dehydrogenase complex (PDHC) deficiency is one type of mitochondrial dysfuntion that is anesthetically associated with lactic acidosis, muscle hypotonia, malignant hyperthermia, and postoperative respiratory failure. We report a case of general anesthetic management during ventriculoperitoneal shunt in a pediatric patient with PDHC deficiency and its possible considerations.
Acidosis, Lactic ; Brain ; Humans ; Malignant Hyperthermia ; Muscle Hypotonia ; Muscles ; Pyruvate Dehydrogenase Complex ; Pyruvic Acid ; Respiratory Insufficiency ; Ventriculoperitoneal Shunt

High extracellular glucose concentration was reported to suppress intracellular Ca2+ clearing through altered sarcoplasmic reticulum (SR) function. In the present study, we attempted to elucidate the effects of pyruvate and fatty acid on SR function and reveal the mechanistic link with glucose-induced SR dysfunction. For this purpose, SR Ca2+-uptake rate was measured in digitonin-permeabilized H9c2 cardiomyocytes cultured in various conditions. Exposure of these cells to 5 mM pyruvate for 2 days induced a significant suppression of SR Ca2+-uptake, which was comparable to the effects of high glucose. These effects were accompanied with decreased glucose utilization. However, pyruvate could not further suppress SR Ca2+-uptake in cells cultured in high glucose condition. Enhanced entry of pyruvate into mitochondria by dichloroacetate, an activator of pyruvate dehydrogenase complex, also induced suppression of SR Ca2+-uptake, indicating that mitochondrial uptake of pyruvate is required in the SR dysfunction induced by pyruvate or glucose. On the other hand, augmentation of fatty acid supply by adding 0.2 to 0.8 mM oleic acid resulted in a dose-dependent suppression of SR Ca2+-uptake. However, these effects were attenuated in high glucose-cultured cells, with no significant changes by oleic acid concentrations lower than 0.4 mM. These results demonstrate that (1) increased pyruvate oxidation is the key mechanism in the SR dysfunction observed in high glucose-cultured cardiomyocytes; (2) exogenous fatty acid also suppresses SR Ca2+-uptake, presumably through a mechanism shared by glucose.
Diabetic Cardiomyopathies* ; Dichloroacetic Acid ; Glucose ; Hand ; Mitochondria ; Myocytes, Cardiac* ; Oleic Acid ; Pyruvate Dehydrogenase Complex ; Pyruvic Acid* ; Sarcoplasmic Reticulum*