Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
 2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although mammalian hibernators rely on stored body fat as a source of energy, direct measurement of energy substrate preference in heart tissue during hibernation, as well as potential mechanisms controlling fatty acid oxidation has not been examined. In order to determine whether an increase in fatty acid utilization occurs during hibernation, glucose and palmitate oxidation were measured in isolated working hearts from hibernating and non-hibernating Richardson's ground Squirrels. Hearts were perfused at either 37 degrees or 5 degrees C with perfusate containing 11 mM [U-14C]glucose and 1.2 mM [9,10-3H]palmitate, which allowed for direct measurement of both glucose oxidation (14CO2 production) and fatty acid oxidation (3H2O production). The contribution of fatty acid oxidation as a source of citric acid cycle acetyl-CoA was significantly greater in hearts from hibernating animals, compared to hearts from non-hibernating animals. Since acetyl-CoA carboxylase (ACC) regulates cardiac fatty acid oxidation (producing malonyl-CoA, a potent inhibitor of mitochondrial fatty acid uptake), we measured the activity and expression of ACC in these hearts. ACC activity was significantly decreased in hibernating ground squirrels, regardless of whether ACC was assayed at 37 degrees or 5 degrees C. This decrease in activity could not be explained by a change in the activity of 5'AMP-activated protein kinase, which can phosphorylate and inhibit ACC. Rather, the expression of the 280 kDa isoform of ACC (which predominates in cardiac muscle) was decreased in hearts from hibernating squirrel hearts. This suggests that a down regulation of ACC expression occurs as an adaptation for the increased utilization of fatty acid in hearts of hibernating ground squirrels.
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PMID:Acetyl-CoA carboxylase control of fatty acid oxidation in hearts from hibernating Richardson's ground squirrels. 951 40

AMP-activated protein kinase (AMPK) is a major sensor and regulator of the energetic state of the cell. Little is known about the specific role of AMPKalpha(2), the major AMPK isoform in the heart, in response to global ischemia. We used AMPKalpha(2)-knockout (AMPKalpha(2)(-/-)) mice to evaluate the consequences of AMPKalpha(2) deletion during normoxia and ischemia, with glucose as the sole substrate. Hemodynamic measurements from echocardiography of hearts from AMPKalpha(2)(-/-) mice during normoxia showed no significant modification compared with wild-type animals. In contrast, the response of hearts from AMPKalpha(2)(-/-) mice to no-flow ischemia was characterized by a more rapid onset of ischemia-induced contracture. This ischemic contracture was associated with a decrease in ATP content, lactate production, glycogen content, and AMPKbeta(2) content. Hearts from AMPKalpha(2)(-/-) mice were also characterized by a decreased phosphorylation state of acetyl-CoA carboxylase during normoxia and ischemia. Despite an apparent worse metabolic adaptation during ischemia, the absence of AMPKalpha(2) does not exacerbate impairment of the recovery of postischemic contractile function. In conclusion, AMPKalpha(2) is required for the metabolic response of the heart to no-flow ischemia. The remaining AMPKalpha(1) cannot compensate for the absence of AMPKalpha(2).
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PMID:Role of the alpha2-isoform of AMP-activated protein kinase in the metabolic response of the heart to no-flow ischemia. 1687 52

DAS-40278-9 maize (corn) plants have been genetically modified by the insertion of the aad-1 gene (aryloxyalkanoate dioxygenase), which confers tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) and aryloxyphenoxypropionate (AOPP) acetyl coenzyme A carboxylase (ACCase) inhibitors ("fop" herbicides) to enable the effective use of these herbicides on maize. The aad-1 gene, derived from Sphingobium herbicidovorans, encodes the aryloxyalkanoate dioxygenase (AAD-1) enzyme. As part of the safety assessment of the AAD-1 protein expressed in maize, acute and repeated dose mammalian toxicology studies were conducted. AAD-1 protein (heterologously produced) was orally administered to mice at a dose of 2000mg/kg, and no acute lethality or adverse effects were observed. Similarly, no adverse effects were observed in mice in a 28-day repeated-dose dietary toxicity study that incorporated the AAD-1 protein into diets at concentrations up to 1000-fold greater than the highest estimate of human exposure to maize. These results support the conclusion that the AAD-1 protein, as expressed in biotechnology derived DAS-40278-9 maize, represents a negligible risk to human health.
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PMID:Acute and 28-day repeated dose toxicology studies in mice with aryloxyalkanoate dioxygenase (AAD-1) protein expressed in 2,4-D tolerant DAS-40278-9 maize. 2210 Jul 18

Maternal hypoxia is associated with a decrease in left ventricular capillary density while cardiac performance is preserved, implying a mismatch between metabolism and diffusive exchange. We hypothesised this requires a switch in substrate metabolism to maximise efficiency of ATP production from limited oxygen availability. Rat pups from pregnant females exposed to hypoxia (FIO2=0.12) at days 10-20 of pregnancy were grown to adulthood and working hearts perfused ex vivo. 14C-labelled glucose and 3H-palmitate were provided as substrates and metabolism quantified from recovery of 14CO2 and 3H2O, respectively. Hearts of male offspring subjected to Maternal Hypoxia showed a 20% decrease in cardiac output (P<0.05), despite recording a 2-fold increase in glucose oxidation (P<0.01) and 2.5-fold increase (P<0.01) in palmitate oxidation. Addition of insulin to Maternal Hypoxic hearts, further increased glucose oxidation (P<0.01) and suppressed palmitate oxidation (P<0.05), suggesting preservation in insulin signalling in the heart. In vitro enzyme activity measurements showed that Maternal Hypoxia increased both total and the active component of cardiac pyruvate dehydrogenase (both P<0.01), although pyruvate dehydrogenase sensitivity to insulin was lost (NS), while citrate synthase activity declined by 30% (P<0.001) and acetyl-CoA carboxylase activity was unchanged by Maternal Hypoxia, indicating realignment of the metabolic machinery to optimise oxygen utilisation. Capillary density was quantified and oxygen diffusion characteristics examined, with calculated capillary domain area increased by 30% (P<0.001). Calculated metabolic efficiency decreased 4-fold (P<0.01) for Maternal Hypoxia hearts. Paradoxically, the decline in citrate synthase activity and increased metabolism suggest that the scope of individual mitochondria had declined, rendering the myocardium potentially more sensitive to metabolic stress. However, decreasing citrate synthase may be essential to preserve local PO2, minimising regions of hypoxia and hence maximising the area of myocardium able to preserve cardiac output following maternal hypoxia.
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PMID:Maternal hypoxia decreases capillary supply and increases metabolic inefficiency leading to divergence in myocardial oxygen supply and demand. 2603 Mar 53