Branched-Chain Keto-Acids and Pyruvate in Blood: Measurement by HPLC with Fluorimetric Detection and Changes in Older Subjects

Pailla, Karine; Blonde-Cynober, F.; Aussel, Christian; Bandt, Jean‐Pascal De; Cynober, Luc

doi:10.1093/clinchem/46.6.848

Cited by 60 publications

(27 citation statements)

References 23 publications

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“…It is also highly probable that α-keto acid substrates of the glutamine transaminase reaction are obtained exogenously from the circulation. In this context, α-keto acid substrates such as pyruvate and the branched-chain α-keto acids are present in human serum in the range of 10-100 µM [46]. Moreover, it has been shown that KMB and the branched-chain α-keto acids are transported across the blood-brain barrier, possibly on the monocarboxylate carrier [47].…”

Section: The Glutaminase II Pathway Permits the Formation Of A-ketoglmentioning

confidence: 99%

High Levels of Glutaminase II Pathway Enzymes in Normal and Cancerous Prostate Suggest a Role in ‘Glutamine Addiction’

Dorai

Pinto

et al. 2019

Biomolecules

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Many tumors readily convert l-glutamine to α-ketoglutarate. This conversion is almost invariably described as involving deamidation of l-glutamine to l-glutamate followed by a transaminase (or dehydrogenase) reaction. However, mammalian tissues possess another pathway for conversion of l-glutamine to α-ketoglutarate, namely the glutaminase II pathway: l-Glutamine is transaminated to α-ketoglutaramate, which is then deamidated to α-ketoglutarate by ω-amidase.Here we show that glutamine transaminase and ω-amidase specific activities are high in normal rat prostate. Immunohistochemical analyses revealed that glutamine transaminase K (GTK) and ω-amidase are present in normal and cancerous human prostate and that expression of these enzymes increases in parallel with aggressiveness of the cancer cells. Our findings suggest that the glutaminase II pathway is important in providing anaplerotic carbon to the tricarboxylic acid (TCA) cycle, closing the methionine salvage pathway, and in the provision of citrate carbon in normal and cancerous prostate. Finally, our data also suggest that selective inhibitors of GTK and/or ω-amidase may be clinically important for treatment of prostate cancer. In conclusion, the demonstration of a prominent glutaminase II pathway in prostate cancer cells and increased expression of the pathway with increasing aggressiveness of tumor cells provides a new perspective on 'glutamine addiction' in cancers.

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Section: The Glutaminase II Pathway Permits the Formation Of A-ketoglmentioning

confidence: 99%

High Levels of Glutaminase II Pathway Enzymes in Normal and Cancerous Prostate Suggest a Role in ‘Glutamine Addiction’

Dorai

Pinto

et al. 2019

Biomolecules

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“…Separation of the o-phthaldialdehyde amino acid derivatives was made by gradient elution from a Supelcosil ™ LC-18 column (15cm × 4.6 mm, 3μm) (Sigma) (Wu and Knabe, 1994). Plasma α-ketoacids were derivitized with o-phenylenediamine and separation was made by gradient elution from a Spherisorb ™ ODS2 column (250mm × 4.6 mm, 5μm; Waters) (Pailla et al, 2000). Total plasma BCAA concentrations were also measured by an enzymatic method (Beckett, 2000).…”

Section: Analytical Proceduresmentioning

confidence: 99%

Disruption of BCATm in Mice Leads to Increased Energy Expenditure Associated with the Activation of a Futile Protein Turnover Cycle

et al. 2007

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Leucine is recognized as a nutrient signal; however, the long-term in vivo consequences of leucine signaling and the role of branched-chain amino acid (BCAA) metabolism in this signaling remain unclear. To investigate these questions, we disrupted the BCATm gene, which encodes the enzyme catalyzing the first step in peripheral BCAA metabolism. BCATm(-/-) mice exhibited elevated plasma BCAAs and decreased adiposity and body weight, despite eating more food, along with increased energy expenditure, remarkable improvements in glucose and insulin tolerance, and protection from diet-induced obesity. The increased energy expenditure did not seem to be due to altered locomotor activity, uncoupling proteins, sympathetic activity, or thyroid hormones but was strongly associated with food consumption and an active futile cycle of increased protein degradation and synthesis. These observations suggest that elevated BCAAs and/or loss of BCAA catabolism in peripheral tissues play an important role in regulating insulin sensitivity and energy expenditure.

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“…Branched-chain a-keto-acids determination BCKA were analysed as reported by Pailla et al (18) . BCKA were derivatised with o-phenylenediamine to give fluorescent derivates, which were separated chromatographically on a reversed-phase column (Spherisorb ODS-2, 4•6 £ 250 mm, 5 mm particles, Waters, Eschborn, Germany) using a binary gradient (L-7100, Merck-Hitachi, Tokyo, Japan).…”

Section: Plasma-free Amino Acidsmentioning

confidence: 99%

The effects of branched-chain amino acid interactions on growth performance, blood metabolites, enzyme kinetics and transcriptomics in weaned pigs

2010

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The impact of excess dietary leucine (Leu) was studied in two growth assays with pigs (8-25 kg). In each trial, forty-eight pigs were allotted to one of six dietary groups. The dietary Leu supply increased from treatment L100 to L200 (three increments). To guarantee that interactions between the branched-chain amino acids (BCAA) were not cushioned either surpluses of isoleucine (Ile, expt 1) or valine (Val; expt 2) were avoided. In the fifth treatment, the effects of a simultaneous excess of Leu and Val (expt 1), or of Leu and Ile (expt 2) were investigated. The sixth treatment was a positive control. An increase in dietary Leu decreased growth performance, and increased plasma Leu and serum a-keto-isocaproate levels in a linear, dose-dependent manner. Levels of plasma Ile and Val, and of serum a-keto-b-methylvalerate and a-keto-isovalerate, indicated increased catabolism. Linear increases in the activity of basal branched-chain a-keto acid dehydrogenase in the liver confirmed these findings. No major alterations occurred in the mRNA of branched-chain amino acid catabolism genes. In liver tissue from expt 2, however, the mRNA levels of growth hormone receptor, insulin-like growth factor acid labile subunit and insulin-like growth factor 1 decreased significantly with increasing dietary Leu. In conclusion, excess dietary Leu increased the catabolism of BCAA mainly through posttranscriptional mechanisms. The impact of excess Leu on the growth hormone -insulin-like growth factor-1 axis requires further investigation.Leucine excess: Amino acid interactions: Branched-chain a-keto acid dehydrogenase: PigsInteractions among the branched-chain amino acids (BCAA), such as the performance depressing effects of excess dietary leucine (Leu), are known in several species (1) . The impact of high dietary Leu levels needs to be elucidated in order to make correct estimates of adequate supplies and requirements for isoleucine (Ile) and valine (Val). Interactions among the BCAA include their catabolism, because all three compete for the same enzymes that catalyse the first two catabolic steps. The first step is a reversible transamination catalysed by the branched-chain amino acid transaminase (BCAT) isoenzymes, yielding branched-chain a-keto-acids (BCKA) that, in the second step, are oxidatively decarboxylated by a mitochondrial, multienzyme branchedchain a-keto acid dehydrogenase (BCKDH) complex. This step is irreversible, highly regulated and rate limiting for BCAA catabolism. The BCKDH complex consists of three catalytic components. The E1 subunit, a heterotetramer of a and b subunits, is a branched-chain a-keto acid decarboxylase. The E2 subunit is a dihydrolipoamide acyltransferase and the E3 subunit is a dihydrolipoamide dehydrogenase (2) . In contrast to the other subunits, the E3 is not BCKDHspecific and its expression is not analysed in the present work. BCKDH complex activity is regulated by covalent modification. Phosphorylation of its E1a subunits by a specific BCKDH kinase (BDKDK) causes inactivation, and dephospho...

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Branched-Chain Keto-Acids and Pyruvate in Blood: Measurement by HPLC with Fluorimetric Detection and Changes in Older Subjects

Cited by 60 publications

References 23 publications

High Levels of Glutaminase II Pathway Enzymes in Normal and Cancerous Prostate Suggest a Role in ‘Glutamine Addiction’

High Levels of Glutaminase II Pathway Enzymes in Normal and Cancerous Prostate Suggest a Role in ‘Glutamine Addiction’

Disruption of BCATm in Mice Leads to Increased Energy Expenditure Associated with the Activation of a Futile Protein Turnover Cycle

The effects of branched-chain amino acid interactions on growth performance, blood metabolites, enzyme kinetics and transcriptomics in weaned pigs

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