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

Metabolic alterations in ventromedial hypothalamus (VMH)-lesioned rats were investigated by examining daily changes of enzyme activities and urea concentrations three weeks after the operation. VMH-lesions in female adult rats caused a significant elevation in the activity of acetyl-CoA carboxylase in the liver and parametrial adipose tissue. These changes suggest an increased lipogenesis. VMH-lesions also elicited an increase in activities of glucokinase (GK), pyruvate kinase (PK) and fructose 1,6-bisphosphatase (FBPase), and a decrease in activities of phosphofructokinase (PFK), glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) in the liver. The apparently inconsistent changes in activities of key glycolytic enzymes, GK, PK and PFK, and key gluconeogenic enzymes, G6Pase, PEPCK and FBPase in the liver may be explained by the fact that they were favorable for glucose oxidation through pentose phosphate cycle and provide NADPH for lipogenesis in the liver. Furthermore, VMH-lesions induced an increase in urea contents of the liver and serum, and elicited an increase in activity of liver tyrosine aminotransferase (TAT) and a decrease in activity of liver histidase. These changes suggest an accelerated amino acid and protein catabolism, and favor an increment in the supply of the substrate for lipogenesis. Daily rhythms of TAT, histidase activities and serum urea concentration observed in the control rats were abolished by VMH-lesions. These findings suggest that VMH-lesions elicit the loss of these daily rhythms, probably through the disturbance of the circadian rhythm of feeding behavior at this dynamic phase (three weeks after operation) of obesity.
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PMID:Shift of metabolism in rats with ventromedial hypothalamic lesions with respect to changes in daily rhythms of enzyme activity. 614 67

The effect of feeding casein, lactalbumin, soya-bean protein, gluten or gelatin on hepatic lipogenesis and the levels of hepatic fatty acid synthetase (FAS), glucose-6-phosphate dehydrogenase (EC 1.1.1.49; G6PD), malic enzyme (EC 1.1.1.40; ME) ATP-citrate lyase (EC 4.1.3.8; CL), acetyl CoA carboxylase (EC 6.4.1.2; ACCx) and glucokinase (EC 2.7.1.2; GK) was examined in young growing rats. The total activities of ACCx, FAS, CL, GK, G6PD, GK, ME and fatty acid synthesis in vivo were positively correlated with protein quality. The specific activities of ACCx, FAS, CL, G6PD and fatty acid synthesis in vivo were positively correlated with protein quality. The specific activities of GK and ME were unrelated to protein quality. The results demonstrate a dissociation between ME and hepatic lipogenesis and suggest a role for the NADPH generated by ME which is not related to the needs of fatty acid synthesis.
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PMID:Hepatic lipogenesis in young rats given proteins of different quality. 674 33

Fatty acid synthetic capacity, investigated both in subcellular fractions and in vivo, is very active in brown adipose tissue of room temperature-acclimated rats. In hyperthyroid animals this tissue, analogously to the liver, exhibits an increased activity of acetyl-CoA carboxylase, fatty acid synthetase and microsomal fatty acid chain elongation, this last mechanism remaining unaffected in mitochondria. An enhancement of reducing capacities of a group of cytoplasmic NADP-dependent enzymes has also been observed in brown adipose tissue of hyperthyroid rats, probably due to a greater use of NADPH in lipogenesis under these conditions. An increase in palmitate oxidation and in polyenoic fatty acids was observed in mitochondria of brown adipose tissue from hyperthyroid animals. The latter increase is related to the importance of these compounds in the regulation of membrane fluidity and probably to an increased resistance to cold in the hyperthyroid state.
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PMID:Effect of hyperthyroidism on lipogenesis in brown adipose tissue of young rats. 684 43

Rates of fatty acid synthesis from lactate and acetate and activities of selected lipogenic and NADPH-generating enzymes were determined in subcutaneous, intermuscular and intramuscular adipose tissues of cattle that were 11-19 months of age. Fatty acid synthesis from lactate and acetate increased from 11 to 13 months of age in subcutaneous and intermuscular adipose tissues; synthesis from lactate increased until 17 months of age. In intramuscular adipose tissue, synthesis from lactate also increased until 17 months of age while that from acetate continually increased. Activities of NADPH-generating enzymes increased in all three fat depots from 11 to 13 months of age, and little change occurred thereafter. Acetyl-CoA carboxylase activity was constant over entire growth period in all depots. Activity of ATP-citrate lyase increased from 11 to 13 months of age in subcutaneous and intermuscular adipose tissues, but did not increase until 19 months of age in intramuscular adipose tissue. In all cases, activities of ATP-citrate lyase were sufficient to support synthesis from lactate; therefore, lactate conversion to fatty acids in bovine adipose tissues seems to use the citrate cleavage pathway for generation of cytosolic acetyl-CoA.
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PMID:Fatty acid synthesis from lactate in growing cattle. 726 74

We examined changes in the enzyme activities and metabolites related to hepatic fatty acid synthesis in fasted rats with sepsis produced by cecal ligation and puncture. Sepsis stimulated the in vivo incorporation of tritiated water into hepatic fatty acids and nonsaponifiable lipids. The activities of acetyl-CoA carboxylase, ATP-citrate lyase, and NADPH-generating enzymes (glucose-6-phosphate dehydrogenase and malic enzyme), the tissue levels of citrate and malonyl-CoA, and the dephosphorylation of carboxylase were increased in the livers of fasted septic rats compared with fasted sham-operated control rats. These results indicate that sepsis stimulated hepatic lipogenesis and sterologenesis in fasting rats. Furthermore, sepsis reduced the specific activity of hepatic mitochondrial carnitine palmitoyltransferase and raised that of glycerophosphate acyltransferase, suggesting an increased diversion of cytosolic acyl-CoA towards esterification. These intrahepatic metabolic changes strongly suggest that sepsis causes anabolic action on hepatic lipid metabolism.
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PMID:Accelerated hepatic lipid synthesis in fasted septic rats. 809 11

Hepatocyte growth factor (HGF)/scatter factor is known to be the most potent mitogen for hepatocytes. In this paper, we report that lipogenesis in primary cultured rat hepatocytes treated with 10 ng/ml of recombinant human HGF (rhHGF) for 24 h was stimulated, as measured by the incorporation of 3H2O into long-chain fatty acids, to more than twice as much as the control. Insulin (0.1 microM) was more effective than rhHGF but rhHGF did not show an additive or synergistic effect when added to insulin. We also showed that treatment with rhHGF increased the activities of glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme, key enzymes which supply NADPH for lipogenesis, and acetyl-CoA carboxylase, the rate-limiting enzyme of lipogenesis. The increase in G6PDH and acetyl-CoA carboxylase activities was accompanied by increases in the levels of mRNA for the enzymes. These results suggest that HGF is involved in liver regeneration not only by stimulation of cell proliferation but also by acceleration of differentiation of hepatocytes.
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PMID:Effect of hepatocyte growth factor/scatter factor on lipogenesis in adult rat hepatocytes in primary culture. 879 95

Fatty acid synthesis in chloroplasts is regulated by light. The synthesis of malonyl-CoA, which is catalyzed by acetyl-CoA carboxylase (ACCase) and is the first committed step, is modulated by light/dark. Plants have ACCase in plastids and the cytosol. To determine the possible involvement of a redox cascade in light/dark modulation of ACCase, the effect of DTT, a known reductant of S-S bonds, was examined in vitro for the partially purified ACCase from pea plant. Only the plastidic ACCase was activated by DTT. This enzyme was activated in vitro more efficiently by reduced thioredoxin, which is a transducer of redox potential during illumination, than by DTT alone. Chloroplast thioredoxin-f activated the enzyme more efficiently than thioredoxin-m. The ACCase also was activated by thioredoxin reduced enzymatically with NADPH and NADP-thioredoxin reductase. These findings suggest that the reduction of ACCase is needed for activation of the enzyme, and a redox potential generated by photosynthesis is involved in its activation through thioredoxin as for enzymes of the reductive pentose phosphate cycle. The catalytic activity of ACCase was maximum at pH 8 and 2-5 mM Mg2+, indicating that light-produced changes in stromal pH and Mg2+ concentration modulate ACCase activity. These results suggest that light directly modulates a regulatory site of plastidic prokaryotic form of ACCase via a signal transduction pathway of a redox cascade and indirectly modulates its catalytic activity via stromal pH and Mg2+ concentration. A redox cascade is likely to link between light and fatty acid synthesis, resulting in coordination of fatty acid synthesis with photosynthesis.
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PMID:Link between light and fatty acid synthesis: thioredoxin-linked reductive activation of plastidic acetyl-CoA carboxylase. 938 Jul 65

We have investigated several factors which influence acetyl-CoA carboxylase (ACCase) activity in lysed spinach chloroplasts. (1) When assayed after rapid lysis of light-incubated chloroplasts, ACCase activity was 2-fold higher than activity from dark-incubated chloroplasts. Within 5 min after lysis, activity from dark-incubated chloroplasts increased, suggesting a transient inactivation or inhibition of ACCase in the dark. (2) When lysed chloroplast suspensions were incubated with 30 to 100 microM acetyl-CoA before starting assays, activity was 4-fold higher than if suspensions were not preincubated with acetyl-CoA. CoA, malonyl-CoA, propionyl-CoA, and butyryl-CoA also activated ACCase. Full acetyl-CoA activation required MgATP and was essentially complete after 8 min. ACCase activity decreased upon removal of acetyl-CoA by gel filtration and was partially restored by readdition of acetyl-CoA. Thus, ACCase activation by acetyl-CoA was reversible. (3) Dithiothreitol and thioredoxin stimulated ACCase activity, but only in preparations where ACCase activity was low. (4) ACCase was assayed in concentrations of ATP, ADP, NADPH, NADP+, Mg2+, and CO2/HCO-3, which are estimated to occur in the stroma of chloroplasts under illumination or darkness. ACCase activity from lysed chloroplast suspensions was 10-fold higher when illuminated conditions were used. However, this activity was still 5-fold to 10-fold lower than the rates required to sustain known in vivo rates of fatty acid synthesis and in vitro rates achieved under optimum assay conditions with saturating substrates.
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PMID:Regulation of spinach chloroplast acetyl-CoA carboxylase. 980 58

Previous studies have shown that the rate of fatty acid synthesis is elevated by more than 20-fold in livers of transgenic mice that express truncated nuclear forms of sterol regulatory element-binding proteins (SREBPs). This was explained in part by an increase in the levels of mRNA for the two major enzymes of fatty acid synthesis, acetyl-CoA carboxylase and fatty acid synthase, whose transcription is stimulated by SREBPs. Fatty acid synthesis also requires a source of acetyl-CoA and NADPH. In the current studies we show that the levels of mRNA for ATP citrate lyase, the enzyme that produces acetyl-CoA, are also elevated in the transgenic livers. In addition, we found marked elevations in the mRNAs for malic enzyme, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase, all of which produce NADPH. Finally, we found that overexpressing two of the SREBPs (1a and 2) led to elevated mRNAs for stearoyl-CoA desaturase 1 (SCD1), an isoform that is detectable in nontransgenic livers, and SCD2, an isoform that is not detected in nontransgenic livers. This stimulation led to an increase in total SCD activity in liver microsomes. Together, all of these changes would be expected to lead to a marked increase in the concentration of monounsaturated fatty acids in the transgenic livers, and this was confirmed chromatographically. We conclude that expression of nuclear SREBPs is capable of activating the entire coordinated program of unsaturated fatty acid biosynthesis in mouse liver.
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PMID:Nuclear sterol regulatory element-binding proteins activate genes responsible for the entire program of unsaturated fatty acid biosynthesis in transgenic mouse liver. 985 71

The pathway of autotrophic CO2 fixation was studied in the phototrophic bacterium Chloroflexus aurantiacus and in the aerobic thermoacidophilic archaeon Metallosphaera sedula. In both organisms, none of the key enzymes of the reductive pentose phosphate cycle, the reductive citric acid cycle, and the reductive acetyl coenzyme A (acetyl-CoA) pathway were detectable. However, cells contained the biotin-dependent acetyl-CoA carboxylase and propionyl-CoA carboxylase as well as phosphoenolpyruvate carboxylase. The specific enzyme activities of the carboxylases were high enough to explain the autotrophic growth rate via the 3-hydroxypropionate cycle. Extracts catalyzed the CO2-, MgATP-, and NADPH-dependent conversion of acetyl-CoA to 3-hydroxypropionate via malonyl-CoA and the conversion of this intermediate to succinate via propionyl-CoA. The labelled intermediates were detected in vitro with either 14CO2 or [14C]acetyl-CoA as precursor. These reactions are part of the 3-hydroxypropionate cycle, the autotrophic pathway proposed for C. aurantiacus. The investigation was extended to the autotrophic archaea Sulfolobus metallicus and Acidianus infernus, which showed acetyl-CoA and propionyl-CoA carboxylase activities in extracts of autotrophically grown cells. Acetyl-CoA carboxylase activity is unexpected in archaea since they do not contain fatty acids in their membranes. These aerobic archaea, as well as C. aurantiacus, were screened for biotin-containing proteins by the avidin-peroxidase test. They contained large amounts of a small biotin-carrying protein, which is most likely part of the acetyl-CoA and propionyl-CoA carboxylases. Other archaea reported to use one of the other known autotrophic pathways lacked such small biotin-containing proteins. These findings suggest that the aerobic autotrophic archaea M. sedula, S. metallicus, and A. infernus use a yet-to-be-defined 3-hydroxypropionate cycle for their autotrophic growth. Acetyl-CoA carboxylase and propionyl-CoA carboxylase are proposed to be the main CO2 fixation enzymes, and phosphoenolpyruvate carboxylase may have an anaplerotic function. The results also provide further support for the occurrence of the 3-hydroxypropionate cycle in C. aurantiacus.
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PMID:Presence of acetyl coenzyme A (CoA) carboxylase and propionyl-CoA carboxylase in autotrophic Crenarchaeota and indication for operation of a 3-hydroxypropionate cycle in autotrophic carbon fixation. 997 33


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