scholarly journals Increase in fatty acid synthetase content of 3T3-L cells undergoing spontaneous and chemically induced differentiation to adipocytes

1979 ◽  
Vol 182 (2) ◽  
pp. 509-514 ◽  
Author(s):  
P M Ahmad ◽  
T R Russell ◽  
F Ahmad
Keyword(s):  
Fatty Acid ◽  
Specific Activity ◽  
Fatty Acid Synthetase ◽  
L Cells ◽  
Differentiated Cells ◽  
Cellular Content ◽  
Chemically Induced ◽  
Low Incidence ◽  
Continuous Presence ◽  
Adipose Cells

3T3-L fibroblasts differentiate into adipose cells when maintained in a non-growing state. The specific activity of fatty acid synthetase of differentiated cells was 25–30-fold higher than that present in 3T3-L fibroblasts or in 3T3-C2 cells that possess an extremely low incidence of differentiation to adipocytes. The results of immunochemical analysis indicate that the increased specific activity of fatty acid synthetase in the differentiated cells is due to an increase in the cellular content of this enzyme. The rate of conversion of adipose cells was accelerated by brief exposure of confluent non-growing cultures of 3T3-L cells to 3-isobutyl-1-methylxanthine. This was accompanied by an increase in the specificity activity of fatty acid synthetase, which was also shown to be due to an increase in the cellular content of this enzyme. The continuous presence of 3-isobutyl-1-methylxanthine in the culture medium was not required to elicit the morphological and biochemical changes in 3T3-L cells that occurred many days after the removal of the inducer but earlier than the onset of spontanous differentiation.

scholarly journals Modulation of lipid-synthesizing enzymes by insulin in differentiated ob17 adipose-like cells

1983 ◽  
Vol 214 (2) ◽  
pp. 443-449 ◽  
Author(s):  
P Grimaldi ◽  
C Forest ◽  
P Poli ◽  
R Negrel ◽  
G Ailhaud
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Specific Activity ◽  
Fatty Acid Synthetase ◽  
Lipid Synthesis ◽  
Acid Synthesis ◽  
Acetate Incorporation ◽  
Long Term Effects ◽  
Response Curves ◽  
Glycerol 3 Phosphate Dehydrogenase

ob17 cells convert into adipose-like cells when maintained in the presence of physiological concentrations of insulin and tri-iodothyronine. After this conversion, insulin removal from differentiated ob17 cells gives within 24-48 h a large decrease in fatty acid synthetase, glycerol 3-phosphate dehydrogenase and acid:CoA ligase activities, as well as in the rate of fatty acid synthesis determined by [14C]acetate incorporation into lipids. All parameters are restored by insulin addition to initial values within 24-48 h. Dose-response curves of insulin on the restoration of glycerol 3-phosphate dehydrogenase activity and of fatty acid synthesis give half-maximally effective concentrations close to 1 nM, in agreement with the affinity for insulin of the insulin receptors previously characterized in these cells. Immunotitration experiments indicate that the changes in the specific activity of fatty acid synthetase are due to parallel changes in the cellular enzyme content. Therefore the ob17 cell line should be a useful model to study the long-term effects of insulin on the modulation of lipid synthesis in adipose cells.

Inhibition of Fatty Acid Synthetase in Halobacterium cutirubrum and Escherichia coli by High Salt Concentrations

1971 ◽  
Vol 49 (8) ◽  
pp. 953-958 ◽  
Author(s):  
E. L. Pugh ◽  
M. K. Wassef ◽  
M. Kates
Keyword(s):  
Fatty Acid ◽  
Sodium Chloride ◽  
Specific Activity ◽  
Fatty Acid Synthetase ◽  
Chloride Concentration ◽  
High Sodium ◽  
E Coli ◽  
Level Of Activity ◽  
Malonyl Coa ◽  
A Cell

A cell-free enzyme preparation from Halobacterium cutirubrum was shown to catalyze the biosynthesis of fatty acids from malonyl-CoA at zero sodium chloride concentration, with a specific activity about [Formula: see text] that of a similarly prepared fatty acid synthetase from E. coli. Both the H. cutirubrum synthetase and that from E. coli were strongly inhibited by high sodium chloride or potassium chloride concentrations (0.5–4 M). The malonyl-CoA: ACP transacylase, which catalyzes the first step in the fatty acid biosynthetic pathway, was shown to be strongly inhibited by salt in H. cutirubrum, but not in E. coli. It is concluded that H. cutirubrum contains a fatty acid synthetase system which normally operates at a very low level of activity as a result of inhibition by the high intracellular salt concentration present in this organism.

Effects of glucocorticoid hormones on lipid-synthetic enzymes from different adipose tissue regions and from liver

1983 ◽  
Vol 61 (12) ◽  
pp. 1245-1250 ◽  
Author(s):  
David C. W. Lau ◽  
Daniel A. K. Roncari
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Specific Activity ◽  
Fatty Acid Synthetase ◽  
Subcellular Fractions ◽  
Fat Tissue ◽  
Synthetic Enzymes ◽  
Regional Effects ◽  
Fat Depots ◽  
Adipose Tissue Depots

The regional diversity of adipose tissue is dramatically accentuated in states of glucocorticoid excess, in which certain fat depots expand, while others contract. We have studied the molecular basis of this redistribution by determining the activity of fatty acid synthetase and enzymes catalyzing di- and tri-acylglycerol synthesis, in subcellular fractions from four adipose depots of rats injected with dexamethasone and from interscapular and epididymal adipocyte precursors after addition of either dexamethasone or corticosterone to confluent monolayers in secondary culture. Subcellular fractions from cervical and interscapular adipose tissue, as well as from cultured interscapular precursors, revealed a general increase in specific enzyme activity. The opposite trend was observed for retroperitoneal and epididymal fat tissue, as well as cultured epididymal precursors. Fatty acid synthetase and cytosolic phosphatidate phosphohydrolase appeared to be most responsive. The findings in culture indicate that the regional effects of glucocorticoids are partly independent of other circulating or neural factors. Injections of dexamethasone led to significantly enhanced specific activity of all the lipid-synthetic enzymes assayed in subcellular fractions from liver. Differences in hormonal influences between liver and certain fat tissue regions represent tissue specificity. In addition, the diverse effects of glucocorticoids on various adipose tissue depots indicate regional or "intratissue" specificity.

scholarly journals Lipogenic enzymes in rat maternal adipose tissue in the perinatal period

1980 ◽  
Vol 186 (3) ◽  
pp. 937-944 ◽  
Author(s):  
P A Sinnett-Smith ◽  
R G Vernon ◽  
R J Mayer
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Pyruvate Dehydrogenase ◽  
Fatty Acid Biosynthesis ◽  
Specific Activity ◽  
Fatty Acid Synthetase ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acid Biosynthesis

1. The specific activities of fatty acid synthetase, acetyl-CoA carboxylase and pyruvate dehydrogenase were measured in rat adipose-tissue extracts in pregnancy and lactation. Fatty acid synthetase specific activity correlates very closely with the rate of fatty acid synthesis, the enzyme specific activity decreasing after mid-pregnancy in a manner very similar to the rate of fatty acid synthesis. Acetyl-CoA carboxylase specific activity also decreases dramatically after mid-pregnancy. Initial pyruvate dehydrogenase specific activity shows a decrease between 2 days pre partum and 2 days post partum, but total enzyme activity shows no significant change in the same period. 2. Immunotitrations of fatty acid synthetase and pyruvate dehydrogenase activities were carried out; the titrations showed that the change in the fatty acid synthetase activity is due to a change in the enzyme amount; the amount of pyruvate dyhydrogenase does not change. Therefore the decrease in fatty acid biosynthesis in subcutaneous and parametrial adipose tissue in late pregnancy and early lactation is associated with a decrease in the amount of at least one of the enzymes involved in fatty acid biosynthesis. The correlation of these events with known hormonal changes is discussed.

scholarly journals Morphological alterations and ganglioside sialyltransferase activity induced by small fatty acids in HeLa cells.

1975 ◽  
Vol 66 (2) ◽  
pp. 414-424 ◽  
Author(s):  
J L Simmons ◽  
P H Fishman ◽  
E Freese ◽  
R O Brady
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Hela Cells ◽  
Specific Activity ◽  
Saturated Fatty Acids ◽  
Morphological Alterations ◽  
Sialyltransferase Activity ◽  
Cell Processes ◽  
Continuous Presence ◽  
Shape Changes

Incubation of HeLa cells in the presence of millimolar concentrations of propionate, butyrate, or pentanoate increases the specific activity of CMP-sialic acid:lactosylceramide sialyltransferase 7-20-fold within 24 h. Longer-chain saturated fatty acids or acetate are much less effective, decanoate showing no induction. Unsaturated fatty acid analogs of butyrate and other compounds are ineffective. Only the three most effective compounds also produce characteristic smooth extended cell processes in HeLa cells. Butyrate (5 mM) induces the sialyltransferase after a 4-h lag, producing maximum specific activity by 24 h. The amount of sialyl-lactosylceramide, the glycolipid product of the enzyme, increases during that time 3.5 times more than in control cultures. No other glycosphingolipid enzyme is significantly altered by butyrate exposure. The cellular shape changes occur 2-3 h later than the increase of sialyltransferase activity, and both processes require the continuous presence of inducer and the synthesis of RNA and protein but not the synthesis of DNA or the presence of serum.

scholarly journals Stoichiometry of substrate binding to rat liver fatty acid synthetase

1985 ◽  
Vol 230 (2) ◽  
pp. 435-440 ◽  
Author(s):  
J Mikkelsen ◽  
S Smith ◽  
A Stern ◽  
J Knudsen
Keyword(s):  
Fatty Acid ◽  
Rat Liver ◽  
Specific Activity ◽  
Substrate Binding ◽  
Fatty Acid Synthetase ◽  
Liver Fatty Acid ◽  
Acetyl Coa ◽  
Malonyl Coa ◽  
Symmetrical Model ◽  
Active Centres

Two rat liver fatty acid synthetase preparations, containing 1.6 and 2.0 mol of 4′-phosphopantetheine/mol of synthetase, showed specific activity of 2006 and 2140 nmol of NADPH oxidized/min per mg of protein respectively. The two synthetase preparations could be loaded with either 3.3-4.4 mol of [1–14] acetate or 2.9-3.7 mol of [2-14C]malonate, by incubation with either [1-14C] acetyl-CoA or [2-14C]malonyl-CoA. The 4′-phosphopantetheine site could be more than 90% saturated and the serine site about 80% saturated with malonate derived from malonyl-CoA. However, with acetyl-CoA as substrate, binding at both the 4′-phosphopantetheine and cysteine thiol sites did not reach saturation. We interpret these results to indicate that, whereas the equilibrium constant for transfer of substrates between the serine loading site and the 4′-phosphopantetheine site is close to unity, that for transfer of acetyl moieties between the 4′-phosphopantetheine and cysteine sites favours formation of the 4′-phosphopantetheine thioester. Thus, despite the apparent sub-stoichiometric binding of acetate, the results are consistent with a functionally symmetrical model for the fatty acid synthetase which permits simultaneous substrate binding at two separate active centres.

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