scholarly journals TGF-β1 is a regulator of the pyruvate dehydrogenase complex in fibroblasts

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Edward R. Smith ◽  
Timothy D. Hewitson
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Aerobic Glycolysis ◽  
Pyruvate Dehydrogenase Complex ◽  
Collagen I ◽  
Acetyl Coa ◽  
Fibroblast Activation ◽  
Molecular Events ◽  
Molecule Inhibitor ◽  
Tgf Β1 ◽  
Dehydrogenase Complex

Abstract TGF-β1 reprograms metabolism in renal fibroblasts, inducing a switch from oxidative phosphorylation to aerobic glycolysis. However, molecular events underpinning this are unknown. Here we identify that TGF-β1 downregulates acetyl-CoA biosynthesis via regulation of the pyruvate dehydrogenase complex (PDC). Flow cytometry showed that TGF-β1 reduced the PDC subunit PDH-E1α in fibroblasts derived from injured, but not normal kidneys. An increase in expression of PDH kinase 1 (PDK1), and reduction in the phosphatase PDP1, were commensurate with net phosphorylation and inactivation of PDC. Over-expression of mutant PDH-E1α, resistant to phosphorylation, ameliorated effects of TGF-β1, while inhibition of PDC activity with CPI-613 was sufficient to induce αSMA and pro-collagen I expression, markers of myofibroblast differentiation and fibroblast activation. The effect of TGF-β1 on PDC activity, acetyl-CoA, αSMA and pro-collagen I was also ameliorated by sodium dichloroacetate, a small molecule inhibitor of PDK. A reduction in acetyl-CoA, and therefore acetylation substrate, also resulted in a generalised loss of protein acetylation with TGF-β1. In conclusion, TGF-β1 in part regulates fibroblast activation via effects on PDC activity.

scholarly journals Evidence for existence of tissue-specific regulation of the mammalian pyruvate dehydrogenase complex

1998 ◽  
Vol 329 (1) ◽  
pp. 191-196 ◽  
Author(s):  
Melissa M. BOWKER-KINLEY ◽  
I. Wilhelmina DAVIS ◽  
Pengfei WU ◽  
A. Robert HARRIS ◽  
M. Kirill POPOV
Keyword(s):  
Tissue Distribution ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Pyruvate Dehydrogenase Kinase ◽  
Synthetic Analogue ◽  
Complex Activity ◽  
Acetyl Coa ◽  
Tissue Specific ◽  
Specific Regulation ◽  
Dehydrogenase Complex

Tissue distribution and kinetic parameters for the four isoenzymes of pyruvate dehydrogenase kinase (PDK1, PDK2, PDK3 and PDK4) identified thus far in mammals were analysed. It appeared that expression of these isoenzymes occurs in a tissue-specific manner. The mRNA for isoenzyme PDK1 was found almost exclusively in rat heart. The mRNA for PDK3 was most abundantly expressed in rat testis. The message for PDK2 was present in all tissues tested but the level was low in spleen and lung. The mRNA for PDK4 was predominantly expressed in skeletal muscle and heart. The specific activities of the isoenzymes varied 25-fold, from 50 nmol/min per mg for PDK2 to 1250 nmol/min per mg for PDK3. Apparent Ki values of the isoenzymes for the synthetic analogue of pyruvate, dichloroacetate, varied 40-fold, from 0.2 mM for PDK2 to 8 mM for PDK3. The isoenzymes were also different with respect to their ability to respond to NADH and NADH plus acetyl-CoA. NADH alone stimulated the activities of PDK1 and PDK2 by 20 and 30% respectively. NADH plus acetyl-CoA activated these isoenzymes nearly 200 and 300%. Under comparable conditions, isoenzyme PDK3 was almost completely unresponsive to NADH, and NADH plus acetyl-CoA caused inhibition rather than activation. Isoenzyme PDK4 was activated almost 2-fold by NADH, but NADH plus acetyl-CoA did not activate above the level seen with NADH alone. These results provide the first evidence that the unique tissue distribution and kinetic characteristics of the isoenzymes of PDK are among the major factors responsible for tissue-specific regulation of the pyruvate dehydrogenase complex activity.

Molecular biology of acetyl-CoA metabolism

2000 ◽  
Vol 28 (6) ◽  
pp. 591-593 ◽  
Author(s):  
B. J. Nikolau ◽  
D. J. Oliver ◽  
P. S. Schnable ◽  
E. S. Wurtele
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Pyruvate Decarboxylase ◽  
Acetyl Coa Carboxylase ◽  
Atp Citrate Lyase ◽  
Acetyl Coa ◽  
Acetaldehyde Dehydrogenase ◽  
Citrate Lyase ◽  
Biochemical Genetic ◽  
Dehydrogenase Complex

We have characterized the expression of potential acetyl-CoA-generating genes (acetyl-CoA synthetase, pyruvate decarboxylase, acetaldehyde dehydrogenase, plastidic pyruvate dehydrogenase complex and ATP-citrate lyase), and compared these with the expression of acetyl-CoA-metabolizing genes (heteromeric and homomeric acetyl-CoA carboxylase). These comparisons have led to the development of testable hypotheses as to how distinct pools of acetyl-CoA are generated and metabolized. These hypotheses are being tested by combined biochemical, genetic and molecular biological experiments, which is providing insights into how acetyl-CoA metabolism is regulated.

scholarly journals Emerging regulatory roles of mitochondrial sirtuins on pyruvate dehydrogenase complex and the related metabolic diseases: Review

2020 ◽  
Vol 7 (2) ◽  
pp. 3645-3658
Author(s):  
Abolfazl Nasiri ◽  
Masoud Sadeghi ◽  
Asad Vaisi-Raygani ◽  
Sara Kiani ◽  
Zahra Aghelan ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Pyruvate Dehydrogenase ◽  
Structural Changes ◽  
Metabolic Diseases ◽  
Pyruvate Dehydrogenase Complex ◽  
Mitochondrial Protein ◽  
Krebs Cycle ◽  
Acetyl Coa ◽  
Dehydrogenase Complex

The pyruvate dehydrogenase complex (PDC) is a multi-enzyme complex of the mitochondria that provides a link between glycolysis and the Krebs cycle. PDC plays an essential role in producing acetyl-CoA from glucose and the regulation of fuel consumption. In general, PDC enzyme is regulated in two different ways, end-product inhibition and posttranslational modifications (more extensive phosphorylation and dephosphorylation subunit E1). Posttranslational modifications of this enzyme are regulated by various factors. Sirtuins are the class III of histone deacylatases that catalyze protein posttranslational modifications, including deacetylation, adenosine diphosphate ribosylation, and deacylation. Sirt3, Sirt4, and Sirt5 are mitochondrial sirtuins that control the posttranslational modifications of mitochondrial protein. Considering the comprehensive role of sirtuins in post-translational modifications and regulation of metabolic processes, the aim of this review is to explore the role of mitochondrial sirtuins in the regulation of the PDC. PDC deficiency is a common metabolic disorder that causes pyruvate to be converted to lactate and alanine rather than to acetyl-CoA. because this enzyme is in the gateway of complete oxidation, glucose products entering the Krebs cycle and resulting in physiological and structural changes in the organs. Metabolic blockage such as ketogenic diet broken up by b -oxidation and producing acetyl-CoA can improve the patients. Sirtuins play a role in the production of acetyl-CoA through oxidation of fatty acids and other pathways. Thus, we hypothesize that the targets and bioactive compounds targeting mitochondrial sirtuins can be involved in the treatment of PDC deficiency. In general, this review discusses the present knowledge on how mitochondrial sirtuins are involved in the regulation of PDC as well as their possible roles in the treatment of PDC deficiency.

scholarly journals The plasticity of the pyruvate dehydrogenase complex confers a labile structure that is associated with its catalytic activity

2020 ◽  
Author(s):  
Jaehyoun Lee ◽  
Seunghee Oh ◽  
Saikat Bhattacharya ◽  
Ying Zhang ◽  
Laurence Florens ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Pyruvate Dehydrogenase ◽  
Biochemical Analysis ◽  
Pyruvate Dehydrogenase Complex ◽  
Size Exclusion ◽  
Dependent Manner ◽  
Acetyl Coa ◽  
Cell Extracts ◽  
Exclusion Chromatography ◽  
Dehydrogenase Complex

ABSTRACTThe pyruvate dehydrogenase complex (PDC) is a multienzyme complex that plays a key role in energy metabolism by converting pyruvate to acetyl-CoA. An increase of nuclear PDC has been shown to be correlated with an increase of histone acetylation that requires acetyl-CoA. PDC has been reported to form a ~ 10 MDa macromolecular machine that is proficient in performing sequential catalytic reactions via its three components. In this study, we show that the PDC displays size versatility in an ionic strength-dependent manner using size exclusion chromatography of yeast cell extracts. Biochemical analysis in combination with mass spectrometry indicates that yeast PDC (yPDC) is a salt-labile complex that dissociates into sub-megadalton individual components even under physiological ionic strength. Interestingly, we find that each oligomeric component of yPDC displays a larger size than previously believed. In addition, we show that the mammalian PDC also displays this uncommon characteristic of salt-lability, although it has a somewhat different profile compared to yeast. We show that the activity of yPDC is reduced in higher ionic strength. Our results indicate that the structure of PDC may not always maintain its ~ 10 MDa organization, but is rather variable. We propose that the flexible nature of PDC may allow modulation of its activity.

scholarly journals Lack of mitochondria-generated acetyl-CoA by pyruvate dehydrogenase complex downregulates gene expression in the hepatic de novo lipogenic pathway

2016 ◽  
Vol 311 (1) ◽  
pp. E117-E127 ◽  
Author(s):  
Saleh Mahmood ◽  
Barbara Birkaya ◽  
Todd C. Rideout ◽  
Mulchand S. Patel
Keyword(s):  
Gene Expression ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Pyruvate Dehydrogenase ◽  
De Novo ◽  
Pyruvate Dehydrogenase Complex ◽  
Acid Oxidation ◽  
Acetyl Coa ◽  
Key Genes ◽  
Dehydrogenase Complex

During the absorptive state, the liver stores excess glucose as glycogen and synthesizes fatty acids for triglyceride synthesis for export as very low density lipoproteins. For de novo synthesis of fatty acids from glucose, the mitochondrial pyruvate dehydrogenase complex (PDC) is the gatekeeper for the generation of acetyl-CoA from glucose-derived pyruvate. Here, we tested the hypothesis that limiting the supply of PDC-generated acetyl-CoA from glucose would have an impact on expression of key genes in the lipogenic pathway. In the present study, although the postnatal growth of liver-specific PDC-deficient (L-PDCKO) male mice was largely unaltered, the mice developed hyperinsulinemia with lower blood glucose levels in the fed state. Serum and liver lipid triglyceride and cholesterol levels remained unaltered in L-PDCKO mice. Expression of several key genes ( ACL, ACC1) in the lipogenic pathway and their upstream regulators ( LXR, SREBP1, ChREBP) as well as several genes in glucose metabolism ( Pklr, G6pd2, Pck1) and fatty acid oxidation ( FAT, Cpt1a) was downregulated in livers from L-PDCKO mice. Interestingly, there was concomitant upregulation of lipogenic genes in adipose tissue from L-PDCKO mice. Although, the total hepatic acetyl-CoA content remained unaltered in L-PDCKO mice, modified acetylation profiles of proteins in the nuclear compartment suggested an important role for PDC-generated acetyl-CoA in gene expression in de novo fatty acid synthesis in the liver. This finding has important implications for the regulation of hepatic lipid synthesis in pathological states.

scholarly journals Pyruvate dehydrogenase complex of ascites tumour. Activation by AMP and other properties of potential significance in metabolic regulation

1980 ◽  
Vol 190 (3) ◽  
pp. 705-710 ◽  
Author(s):  
P A Lazo ◽  
A Sols
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Metabolic Regulation ◽  
Pyruvate Dehydrogenase Complex ◽  
Acetyl Coa ◽  
Substrate Complex ◽  
Ascites Tumour ◽  
Rate Limiting Step ◽  
Lipoamide Dehydrogenase ◽  
Dehydrogenase Complex

1. AMP is an activator of the pyruvate dehydrogenase complex of the Ehrlich—Lettré ascites tumour, increasing its V up to 2-fold, with Ka of 40 microM at pH 7.4. This activation appears to be an allosteric effect on the decarboxylase subunit of the complex. 2. The pyruvate dehydrogenase complex has a Km for pyruvate within the range 17—36 microM depending on the pH, the optimum pH being approx. 7.4, with a V of approx. 0.1 unit/g of cells. The rate-limiting step is dependent on the transformation of the enzyme—substrate complex. The Km for CoA is 15 microM. The Km for NAD+ is 0.7 mM for both the complex and the lipoamide dehydrogenase. The complex is inhibited by acetyl-CoA competitively with CoA; the Ki is 60 microM. The lipoamide dehydrogenase is inhibited by NADH and NADPH competitively with NAD+, with Ki values of 80 and 90 microM respectively. In the reverse reaction the Km values for NADH and NADPH are essentially equal to their Ki values for the forward reaction, the V for the latter being 0.09 of that of the former. Hence the reaction rate of the complex in vivo is likely to be markedly affected by feedback isosteric inhibition by reduced nicotinamide nucleotides and possibly acetyl-CoA.

scholarly journals Nematode pyruvate dehydrogenase kinases: role of the C-terminus in binding to the dihydrolipoyl transacetylase core of the pyruvate dehydrogenase complex

1999 ◽  
Vol 339 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Wei CHEN ◽  
Patricia R. KOMUNIECKI ◽  
Richard KOMUNIECKI
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Binding Assays ◽  
Acetyl Coa ◽  
C Elegans ◽  
Apparent Homogeneity ◽  
C Terminus ◽  
Free Living Nematode ◽  
Direct Binding ◽  
Dehydrogenase Complex

Pyruvate dehydrogenase kinases (PDKs) from the anaerobic parasitic nematode Ascaris suum and the free-living nematode Caenorhabditis elegans were functionally expressed with hexahistidine tags at their N-termini and purified to apparent homogeneity. Both recombinant PDKs (rPDKs) were dimers, were not autophosphorylated and exhibited similar specific activities with the A. suum pyruvate dehydrogenase (E1) as substrate. In addition, the activities of both PDKs were activated by incubation with PDK-depleted A. suum muscle pyruvate dehydrogenase complex (PDC) and were stimulated by NADH and acetyl-CoA. However, the recombinant A. suum PDK (rAPDK) required higher NADH/NAD+ ratios for half-maximal stimulation than the recombinant C. elegans PDK (rCPDK) or values reported for mammalian PDKs, as might be predicted by the more reduced microaerobic mitochondrial environment of the APDK. Limited tryptic digestion of both rPDKs yielded stable fragments truncated at the C-termini (trPDKs). The trPDKs retained their dimeric structure and exhibited substantial PDK activity with the A. suum E1 as substrate, but PDK activity was not activated by incubation with PDK-depleted A. suum PDC or stimulated by elevated NADH/NAD+ or acetyl-CoA/CoA ratios. Direct-binding assays demonstrated that increasing amounts of rCPDK bound to the A. suum PDK-depleted PDC. No additional rCPDK binding was observed at ratios greater than 20 mol of rCPDK/mol of PDC. In contrast, the truncated rCPDK (trCPDK) did not exhibit significant binding to the PDC. Similarly, a truncated form of rCPDK, rCPDK1–334, generated by mutagenesis, exhibited properties similar to those observed for trCPDK. These results suggest that the C-terminus of the PDK is not required for subunit association of the homodimer or catalysis, but instead seems to be involved in the binding of the PDKs to the dihydrolipoyl transacetylase core of the complex.

scholarly journals The plasticity of the pyruvate dehydrogenase complex confers a labile structure that is associated with its catalytic activity

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243489
Author(s):  
Jaehyoun Lee ◽  
Seunghee Oh ◽  
Saikat Bhattacharya ◽  
Ying Zhang ◽  
Laurence Florens ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Pyruvate Dehydrogenase ◽  
Biochemical Analysis ◽  
Pyruvate Dehydrogenase Complex ◽  
Size Exclusion ◽  
Dependent Manner ◽  
Acetyl Coa ◽  
Cell Extracts ◽  
Exclusion Chromatography ◽  
Dehydrogenase Complex

The pyruvate dehydrogenase complex (PDC) is a multienzyme complex that plays a key role in energy metabolism by converting pyruvate to acetyl-CoA. An increase of nuclear PDC has been shown to be correlated with an increase of histone acetylation that requires acetyl-CoA. PDC has been reported to form a ~ 10 MDa macromolecular machine that is proficient in performing sequential catalytic reactions via its three components. In this study, we show that the PDC displays size versatility in an ionic strength-dependent manner using size exclusion chromatography of yeast cell extracts. Biochemical analysis in combination with mass spectrometry indicates that yeast PDC (yPDC) is a salt-labile complex that dissociates into sub-megadalton individual components even under physiological ionic strength. Interestingly, we find that each oligomeric component of yPDC displays a larger size than previously believed. In addition, we show that the mammalian PDC also displays this uncommon characteristic of salt-lability, although it has a somewhat different profile compared to yeast. We show that the activity of yPDC is reduced in higher ionic strength. Our results indicate that the structure of PDC may not always maintain its ~ 10 MDa organization, but is rather variable. We propose that the flexible nature of PDC may allow modulation of its activity.

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