Mammalian target of rapamycin (mTOR) controls cellular anabolism, and mTOR signaling is hyperactive in most cancer cells. As a result, inhibition of mTOR signaling benefits cancer patients. Rapamycin is a US Food and Drug Administration (FDA)-approved drug, a specific mTOR complex 1 (mTORC1) inhibitor, for the treatment of several different types of cancer. However, rapamycin is reported to inhibit cancer growth rather than induce apoptosis. Pyruvate dehydrogenase complex (PDHc) is the gatekeeper for mitochondrial pyruvate oxidation. PDHc inactivation has been observed in a number of cancer cells, and this alteration protects cancer cells from senescence and nicotinamide adenine dinucleotide (NAD^+‍) exhaustion. In this paper, we describe our finding that rapamycin treatment promotes pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1) phosphorylation and leads to PDHc inactivation dependent on mTOR signaling inhibition in cells. This inactivation reduces the sensitivity of cancer cells' response to rapamycin. As a result, rebooting PDHc activity with dichloroacetic acid (DCA), a pyruvate dehydrogenase kinase (PDK) inhibitor, promotes cancer cells' susceptibility to rapamycin treatment in vitro and in vivo.
Humans ; Sirolimus/pharmacology* ; Dichloroacetic Acid/pharmacology* ; Pyruvate Dehydrogenase Complex ; TOR Serine-Threonine Kinases ; Mechanistic Target of Rapamycin Complex 1 ; Neoplasms/drug therapy*

OBJECTIVE: To analyze the clinical and genetic characteristics of a patient with dihydrolipoamide dehydrogenase deficiency. METHODS: Potential variants of the DLD gene were detected by whole exome sequencing and verified by Sanger sequencing. RESULTS: Compound heterozygous variants, c.704_705delTT (p.Leu235Argfs*8) and c.1058T>C (p.Ile353Thr), were detected in the DLD gene. The c.1058T>C (p.Ile353Thr) variant was derived from his mother and known to be pathogenic. The c.704_705delTT (p.Leu235Argfs*8) variant was derived from his father and was unreported previously. CONCLUSION The compound heterozygous variants of c.704_705delTT (p.Leu235Argfs*8) and c.1058T>C (p.Ile353Thr) of the DLD gene probably underlay the disease in this patient. Above finding has facilitated genetic counseling and prenatal diagnosis for the family.
Acidosis, Lactic/genetics* ; Dihydrolipoamide Dehydrogenase/genetics* ; Female ; Genetic Testing ; Genetic Variation ; Humans ; Male ; Maple Syrup Urine Disease/genetics* ; Pregnancy ; Whole Exome Sequencing

OBJECTIVE: To investigate the effect of Shenmai injection on myocardial cells with oxidative injury and the underlying mechanisms. METHODS: Tert-butyl hydroperoxide (t-BHP) was used to induce the oxidative stress in H9c2 myocardial cells. The cell viability and ATP level were evaluated using MTT-colorimetric method and CellTiter-Glo luminescent cell viability assay. The oxygen respiration rate was examined by Clark oxygen electrode. Pyruvate and pyruvate dehydrogenase (PDH) levels were evaluated by ELISA kit. Western blot and quantitative real-time RT-PCR were employed to evaluate the expression of pyruvate dehydrogenase alpha 1(PDHA1) and pyruvate dehydrogenase kinase 1(PDK1). RESULTS: Shenmai injection significantly improved viability and respiration of H9c2 myocardial cells after t-BHP injury (<0.05 or <0.01). It increased ATP contents by consuming pyruvate and increasing PDH level (<0.05 or <0.01). Furthermore, Shenmai injection had the tendency to increase protein expression of PDHA1(<0.05) and decrease mRNA expression of PDK1 (>0.05). CONCLUSIONS Shenmai injection protects mitochondria from oxidative stress by increasing PDH level, which indicates that it may improve energy metabolism of myocardial cells.
Animals ; Cell Line ; Cell Survival ; drug effects ; Drug Combinations ; Drugs, Chinese Herbal ; pharmacology ; Gene Expression Regulation ; drug effects ; Mitochondria ; drug effects ; Myocytes, Cardiac ; drug effects ; Oxidative Stress ; Protein-Serine-Threonine Kinases ; genetics ; Pyruvate Dehydrogenase (Lipoamide) ; genetics ; Rats

Mitochondrial dysfunction is a hallmark of metabolic diseases such as obesity, type 2 diabetes mellitus, neurodegenerative diseases, and cancers. Dysfunction occurs in part because of altered regulation of the mitochondrial pyruvate dehydrogenase complex (PDC), which acts as a central metabolic node that mediates pyruvate oxidation after glycolysis and fuels the Krebs cycle to meet energy demands. Fine-tuning of PDC activity has been mainly attributed to post-translational modifications of its subunits, including the extensively studied phosphorylation and de-phosphorylation of the E1α subunit of pyruvate dehydrogenase (PDH), modulated by kinases (pyruvate dehydrogenase kinase [PDK] 1-4) and phosphatases (pyruvate dehydrogenase phosphatase [PDP] 1-2), respectively. In addition to phosphorylation, other covalent modifications, including acetylation and succinylation, and changes in metabolite levels via metabolic pathways linked to utilization of glucose, fatty acids, and amino acids, have been identified. In this review, we will summarize the roles of PDC in diverse tissues and how regulation of its activity is affected in various metabolic disorders.
Acetylation ; Amino Acids ; Citric Acid Cycle ; Diabetes Mellitus, Type 2 ; Fatty Acids ; Glucose ; Glycolysis ; Metabolic Diseases ; Metabolic Networks and Pathways ; Metabolism* ; Mitochondria ; Neurodegenerative Diseases ; Obesity ; Oxidative Phosphorylation ; Oxidoreductases ; Phosphoric Monoester Hydrolases ; Phosphorylation ; Phosphotransferases ; Protein Processing, Post-Translational ; Pyruvate Dehydrogenase Complex* ; Pyruvic Acid*

Mitochondria are crucial for maintaining the properties of embryonic stem cells (ESCs) and for regulating their subsequent differentiation into diverse cell lineages, including cardiomyocytes. However, mitochondrial regulators that manage the rate of differentiation or cell fate have been rarely identified. This study aimed to determine the potential mitochondrial factor that controls the differentiation of ESCs into cardiac myocytes. We induced cardiomyocyte differentiation from mouse ESCs (mESCs) and performed microarray assays to assess messenger RNA (mRNA) expression changes at differentiation day 8 (D8) compared with undifferentiated mESCs (D0). Among the differentially expressed genes, Pdp1 expression was significantly decreased (27-fold) on D8 compared to D0, which was accompanied by suppressed mitochondrial indices, including ATP levels, membrane potential, ROS and mitochondrial Ca²⁺. Notably, Pdp1 overexpression significantly enhanced the mitochondrial indices and pyruvate dehydrogenase activity and reduced the expression of cardiac differentiation marker mRNA and the cardiac differentiation rate compared to a mock control. In confirmation of this, a knockdown of the Pdp1 gene promoted the expression of cardiac differentiation marker mRNA and the cardiac differentiation rate. In conclusion, our results suggest that mitochondrial PDP1 is a potential regulator that controls cardiac differentiation at an early differentiation stage in ESCs.
Adenosine Triphosphate ; Animals ; Cell Lineage ; Embryonic Stem Cells ; Membrane Potentials ; Mice* ; Mitochondria ; Mouse Embryonic Stem Cells* ; Myocytes, Cardiac* ; Oxidoreductases ; Pyruvate Dehydrogenase (Lipoamide)-Phosphatase* ; Pyruvic Acid* ; RNA, Messenger

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

Impaired glucose homeostasis is one of the risk factors for causing metabolic diseases including obesity, type 2 diabetes, and cancers. In glucose metabolism, pyruvate dehydrogenase complex (PDC) mediates a major regulatory step, an irreversible reaction of oxidative decarboxylation of pyruvate to acetyl-CoA. Tight control of PDC is critical because it plays a key role in glucose disposal. PDC activity is tightly regulated using phosphorylation by pyruvate dehydrogenase kinases (PDK1 to 4) and pyruvate dehydrogenase phosphatases (PDP1 and 2). PDKs and PDPs exhibit unique tissue expression patterns, kinetic properties, and sensitivities to regulatory molecules. During the last decades, the up-regulation of PDKs has been observed in the tissues of patients and mammals with metabolic diseases, which suggests that the inhibition of these kinases may have beneficial effects for treating metabolic diseases. This review summarizes the recent advances in the role of specific PDK isoenzymes on the induction of metabolic diseases and describes the effects of PDK inhibition on the prevention of metabolic diseases using pharmacological inhibitors. Based on these reports, PDK isoenzymes are strong therapeutic targets for preventing and treating metabolic diseases.
Acetyl Coenzyme A ; Decarboxylation ; Diabetes Mellitus, Type 2 ; Glucose ; Homeostasis ; Humans ; Isoenzymes ; Mammals ; Metabolic Diseases ; Metabolism ; Obesity ; Oxidoreductases* ; Phosphoric Monoester Hydrolases ; Phosphorylation ; Phosphotransferases* ; Pyruvate Dehydrogenase Complex ; Pyruvic Acid* ; Risk Factors ; Up-Regulation

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

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*

Since the mitochondrial pyruvate dehydrogenase complex (PDC) controls the rate of carbohydrate oxidation, impairment of PDC activity mediated by high-fat intake has been advocated as a causative factor for the skeletal muscle insulin resistance, metabolic syndrome, and the onset of type 2 diabetes (T2D). There are also situations where muscle insulin resistance can occur independently from high-fat dietary intake such as sepsis, inflammation, or drug administration though they all may share the same underlying mechanism, i.e., via activation of forkhead box family of transcription factors, and to a lower extent via peroxisome proliferator-activated receptors. The main feature of T2D is a chronic elevation in blood glucose levels. Chronic systemic hyperglycaemia is toxic and can lead to cellular dysfunction that may become irreversible over time due to deterioration of the pericyte cell's ability to provide vascular stability and control to endothelial proliferation. Therefore, it may not be surprising that T2D's complications are mainly macrovascular and microvascular related, i.e., neuropathy, retinopathy, nephropathy, coronary artery, and peripheral vascular diseases. However, life style intervention such as exercise, which is the most potent physiological activator of muscle PDC, along with pharmacological intervention such as administration of dichloroacetate or L-carnitine can prove to be viable strategies for treating muscle insulin resistance in obesity and T2D as they can potentially restore whole body glucose disposal.
Blood Glucose ; Carnitine ; Coronary Vessels ; Diabetes Mellitus, Type 2 ; Dichloroacetic Acid ; Diet, High-Fat ; Glucose ; Humans ; Hydroxymethylglutaryl-CoA Reductase Inhibitors ; Inflammation ; Insulin Resistance* ; Life Style ; Muscle, Skeletal ; Muscles ; Obesity ; Pericytes ; Peripheral Vascular Diseases ; Peroxisome Proliferator-Activated Receptors ; Pyruvate Dehydrogenase Complex* ; Sepsis ; Transcription Factors