scholarly journals Alteration in gene expression of branched-chain keto acid dehydrogenase kinase but not in gene expression of its substrate in the liver of clofibrate-treated rats

1996 ◽  
Vol 317 (2) ◽  
pp. 411-417 ◽  
Author(s):  
Harbhajan S. PAUL ◽  
Wei-Qun LIU ◽  
Siamak A. ADIBI
Keyword(s):  
Gene Expression ◽  
Rat Liver ◽  
Fold Increase ◽  
Branched Chain Amino Acids ◽  
The Other ◽  
Mrna Levels ◽  
Keto Acid ◽  
Protein Mass ◽  
Acid Dehydrogenase ◽  
Branched Chain

We previously showed that the oxidation of branched-chain amino acids is increased in rats treated with clofibrate [Paul and Adibi (1980) J. Clin. Invest. 65, 1285–1293]. Two subsequent studies have reported contradictory results regarding the effect of clofibrate treatment on gene expression of branched-chain keto acid dehydrogenase (BCKDH) in rat liver. Furthermore, there has been no previous study of the effect of clofibrate treatment on gene expression of BCKDH kinase, which regulates the activity of BCKDH by phosphorylation. The purpose of the present study was to investigate the above issues. Clofibrate treatment for 2 weeks resulted in (a) a 3-fold increase in the flux through BCKDH in mitochondria isolated from rat liver, and (b) a modest but significant increase in the activity of BCKDH. However, clofibrate treatment had no significant effect on the mass of E1α, E1β, and E2 subunits of BCKDH or the abundance of mRNAs encoding these subunits. On the other hand, clofibrate treatment significantly reduced the activity, the protein mass and the mRNA levels of BCKDH kinase in the liver. In contrast to the results obtained in liver, clofibrate treatment had no significant effect on any of these parameters of BCKDH kinase in the skeletal muscle. In conclusion, our results show that clofibrate treatment increases the activity of BCKDH in the liver and the mechanism of this effect is the inhibition of gene expression of the BCKDH kinase.

scholarly journals Regulation of Branched-Chain α-Keto Acid Dehydrogenase Kinase Expression in Rat Liver

2001 ◽  
Vol 131 (3) ◽  
pp. 841S-845S ◽  
Author(s):  
Robert A. Harris ◽  
Rumi Kobayashi ◽  
Taro Murakami ◽  
Yoshiharu Shimomura
Keyword(s):  
Rat Liver ◽  
Keto Acid ◽  
Acid Dehydrogenase ◽  
Branched Chain ◽  
Kinase Expression

Effects of diabetes and starvation on skeletal muscle branched-chain alpha-keto acid dehydrogenase activity

1988 ◽  
Vol 254 (3) ◽  
pp. E292-E300 ◽  
Author(s):  
R. P. Aftring ◽  
W. J. Miller ◽  
M. G. Buse
Keyword(s):  
Skeletal Muscle ◽  
Insulin Treatment ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Acid Dehydrogenase ◽  
Hindlimb Muscles ◽  
Activation Response ◽  
Branched Chain ◽  
Persistent Elevation ◽  
Significant Activation

The activation state of branched-chain alpha-keto acid dehydrogenase (BCDH) was studied in rat hindlimb muscles during starvation and insulinopenic diabetes, conditions in which circulating branched-chain amino acids (BCAA) are increased and their oxidation is accelerated. Muscle BCDH is predominantly inactive (phosphorylated) in postabsorptive rats but is activated by increased circulating leucine. Diabetes (streptozotocin-induced and spontaneous BB/W) increased circulating BCAA four- to fivefold and BCDH activity approximately threefold. Insulin treatment caused near normalization of circulating BCAA without correcting BCDH activity. Adrenalectomy of diabetics decreased (without normalizing) circulating BCAA and BCDH activation. Starvation caused mild, progressive increases in circulating BCAA and significant activation of BCDH only after 4 days. Leucine infusion activated BCDH in muscle but the activation by leucine was markedly blunted by diabetes. In isolated perfused hindlimbs (control and diabetic) insulin did not affect BCDH significantly; perfusion with leucine activated BCDH, and this response appeared blunted in diabetics. Activation of muscle BCDH may contribute to increased BCAA catabolism in diabetes; the blunted activation response to hyperleucinemia may spare BCAA and contribute to their persistent elevation in plasma.

scholarly journals Interactions among the branched-chain amino acids and their effects on methionine utilization in growing pigs: effects on plasma amino– and keto–acid concentrations and branched-chain keto-acid dehydrogenase activity

2000 ◽  
Vol 83 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Stefan Langer ◽  
Peter W. D. Scislowski ◽  
David S. Brown ◽  
Peter Dewey ◽  
Malcolm F. Fuller
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Concentrations ◽  
Biceps Femoris ◽  
Branched Chain Amino Acids ◽  
Growing Pigs ◽  
Keto Acid ◽  
Blood Samples ◽  
Acid Dehydrogenase ◽  
Branched Chain

The present experiment was designed to elucidate the mechanism of the methionine-sparing effect of excess branched-chain amino acids (BCAA) reported in the previous paper (Langer & Fuller, 2000). Twelve growing gilts (30–35 kg) were prepared with arterial catheters. After recovery, they received for 7 d a semipurified diet with a balanced amino acid pattern. On the 7th day blood samples were taken before (16 h postabsorptive) and after the morning meal (4 h postprandial). The animals were then divided into three groups and received for a further 7 d a methionine-limiting diet (80 % of requirement) (1) without any amino acid excess; (2) with excess leucine (50 % over requirement); or (3) with excesses of all three BCAA (leucine, isoleucine, valine, each 50 % over the requirement). On the 7th day blood samples were taken as in the first period, after which the animals were killed and liver and muscle samples taken. Plasma amino acid and branched-chain keto acid (BCKA) concentrations in the blood and branched-chain keto-acid dehydrogenase (BCKDH; EC 1.2.4.4) activity in liver and muscle homogenates were determined. Compared with those on the balanced diet, pigs fed on methionine-limiting diets had significantly lower (P < 0·05) plasma methionine concentrations in the postprandial but not in the postabsorptive state. There was no effect of either leucine or a mixture of all three BCAA fed in excess on plasma methionine concentrations. Excess dietary leucine reduced (P < 0·05) the plasma concentrations of isoleucine and valine in both the postprandial and postabsorptive states. Plasma concentrations of the BCKA reflected the changes in the corresponding amino acids. Basal BCKDH activity in the liver and total BCKDH activity in the biceps femoris muscle were significantly (P < 0·05) increased by excesses of leucine or all BCAA.

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