Properties of purified rat hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase and regulation of enzyme activity.

Further characterization of a Chinese hamster ovary cell mutant requiring cholesterol and unsaturated fatty acid for growth

“…This tentative conclusion is strengthened by the finding that the increases of each of these activities have been found to revert back to near normal in a spontaneous revertant of the mutant. Although the possibility that a structural gene defect of one of the affected enzymes may exist in the mutant, we consider this possibility highly unlikely, because each of these enzymes is known to be a distinct molecular entity (Clinkenbeard et al, 1973(Clinkenbeard et al, , 1975Edwards et al, 1980;Schneider et al, 1980). No evidence exists which suggests that any two of these enzymes share a common subunit.…”

“…The fact that the mutant cell grown in FCS-M or in DeL-M plus 25hydroxycholesterol responded to compactin treatment in a manner identical with that of the normal CHO cell (Figures 2, 4, and 5) provides strong evidence that the mutant cell is indeed capable of expressing an increase in HMG-CoA reductase activity. Data from Table I and Figure 5 suggested that the effect of compactin on the increase in reductase activity in both cell types was mainly due to an increase in specific protein synthesis (Brown et al, 1978;Edwards et al, 1980) since its effect on a decrease in reductase degradation (Alberts et al, 1981) was not large enough to account for the observed overall increase in activity. These data and those in Figure 3 also showed that the capabilities for protein synthesis and protein degradation of HMG-CoA reductase in the mutant are probably intact.…”

The regulatory effects of fish oil and chitosan on hepatic lipogenic signals in high-fat diet-induced obese rats

“…Hepatic fatty acid synthase (FAS) was determined as described previously by Nepokroeff et al (1975) [ 22 ]. 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase was assayed as described previously by Edwards et al (1980) [ 23 ]. The enzyme activities were determined by the rate of nmole Dihydronicotinamide-adenine dinucleotide phosphate (NADPH) increased.…”

Supplementation of Chitosan Alleviates High-Fat Diet-Enhanced Lipogenesis in Rats via Adenosine Monophosphate (AMP)-Activated Protein Kinase Activation and Inhibition of Lipogenesis-Associated Genes

“…Hepatic fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) were assayed as described previously by Nepokroeff et al 20 and Mohan and Kekwick, 21 respectively. HMGCR reductase was determined as described previously by Edwards et al 22 The enzyme activities were determined by the rate of nanomoles of NADPH increased.…”