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PubMed2006

The prototypical inhibitor of cholesterol esterification, Sah 58-035 [3-[decyldimethylsilyl]-n-[2-(4-methylphenyl)-1-phenylethyl]propanamide], is an agonist of estrogen receptors.

We have shown recently that estrogen receptor (ER) ligands share a diphenyl ethane pharmacophore with Sah 58-035 [3-[decyldimethylsilyl]-N-[2-(4-methylphenyl)-1-phenylethyl]-propanamide], a prototypical inhibitor of the acyl-cholesterolacyl-transferase (ACAT), which enabled us to establish that ER ligands were potent inhibitors of ACAT and blocked the formation of foam cells. In the present study, we have tested whether this structural similarity means that Sah 58-035 is an ER modulator. We report that Sah 58-035 bound to ERalpha and ERbeta with an IC(50) of 2.9 and 3.1 microM, respectively. Docking studies using molecular modeling of Sah 58-035 with the X-ray structure of the ER showed that Sah 58-035 fits well into the ligand binding site known for 4-hydroxy-tamoxifen. Despite having high three-dimensional structural similarities with the pure antiestrogen ICI 164,384 [(N-n-butyl-N-methyl-11-[3,17beta-di-hydroxyestra-1,3, 5(10)-trien-7alpha-yl]-undecanamide], we showed that Sah 58-035 is an agonist of ER for transcription and cellular proliferation. These data showed that Sah 58-035 was an estrogen receptor agonist and that the size and the chemical nature of the side chain were critical for agonist versus antagonist activity on ER. This new molecular mechanism of action for Sah 58-035 has to be taken into account in understanding better its pharmacological activities. Moreover, these data give new structural insights into the understanding of agonist versus antagonist activities of ER ligands and also for the conception of new drugs with a dual ACAT inhibition and ER modulation potential and their evaluation in different pathologies where both targets are involved, such as atherosclerosis, Alzheimer's disease, and cancer.

Amides↗
PubMed2003

Transmembrane movement of exogenous long-chain fatty acids: proteins, enzymes, and vectorial esterification.

The processes that govern the regulated transport of long-chain fatty acids across the plasma membrane are quite distinct compared to counterparts involved in the transport of hydrophilic solutes such as sugars and amino acids. These differences stem from the unique physical and chemical properties of long-chain fatty acids. To date, several distinct classes of proteins have been shown to participate in the transport of exogenous long-chain fatty acids across the membrane. More recent work is consistent with the hypothesis that in addition to the role played by proteins in this process, there is a diffusional component which must also be considered. Central to the development of this hypothesis are the appropriate experimental systems, which can be manipulated using the tools of molecular genetics. Escherichia coli and Saccharomyces cerevisiae are ideally suited as model systems to study this process in that both (i) exhibit saturable long-chain fatty acid transport at low ligand concentrations, (ii) have specific membrane-bound and membrane-associated proteins that are components of the transport apparatus, and (iii) can be easily manipulated using the tools of molecular genetics. In both systems, central players in the process of fatty acid transport are fatty acid transport proteins (FadL or Fat1p) and fatty acyl coenzyme A (CoA) synthetase (FACS; fatty acid CoA ligase [AMP forming] [EC 6.2.1.3]). FACS appears to function in concert with FadL (bacteria) or Fat1p (yeast) in the conversion of the free fatty acid to CoA thioesters concomitant with transport, thereby rendering this process unidirectional. This process of trapping transported fatty acids represents one fundamental mechanism operational in the transport of exogenous fatty acids.

Amino Acid Sequence↗
PubMed1983

In vivo esterification of a synthetic 125I-labeled fatty acid into cardiac glycerolipids.

Recent studies have demonstrated that fatty acids can be successfully utilized as myocardial imaging agents. 125I-paraphenylpentadecanoic acid (IPPA), a synthetic fatty acid, accumulates within the myocardium and can be visualized by conventional gamma scintigraphy. To determine if IPPA was incorporated into cardiac lipids in a pattern similar to palmitate, IPPA was purified by liquid chromatography, bound to fat-free albumin, and administered by intravenous injection to male Sprague-Dawley rats. After 2.5, 5, 10, and 30 min, the hearts were excised and the lipids were extracted in chloroform-methanol. The uptake of IPPA into the myocardium reached a maximal value after 2.5 min, and 95% of the 125I was found in the cardiac lipid fraction after chromatographic separation. Over 65% of the IPPA was found in cardiac triglycerides, whereas approximately 10% was present in membrane phospholipids (predominantly phosphatidylcholine and phosphatidylethanolamine). This pattern of IPPA incorporation is similar to that reported for intravenously administered [3H]palmitate. The rate of turnover of IPPA present in the triglyceride fraction was threefold faster than the rate of the IPPA which was incorporated into membrane lipids. At all time periods examined, the methanol-water soluble end products of IPPA oxidation did not account for more than 5% of the total IPPA present within the myocardium. The present study indicates that IPPA is incorporated primarily into triglycerides and other cardiac lipids in a pattern similar to palmitate.

Animals↗
PubMed2006

Cell proliferation inhibition and alterations in retinol esterification induced by phytanic acid and docosahexaenoic acid.

We investigated the effects of two natural dietary retinoid X receptor (RXR) ligands, phytanic acid (PA) and docosahexaenoic acid (DHA), on proliferation and on the metabolism of retinol (vitamin A) in both cultured normal human prostate epithelial cells (PrECs) and PC-3 prostate carcinoma cells. PA and DHA inhibited the proliferation of the parental PC-3 cells and PC-3 cells engineered to overexpress human lecithin:retinol acyltransferase (LRAT) in both the absence and presence of retinol. A synthetic RXR-specific ligand also inhibited PC-3 cell proliferation, whereas all-trans retinoic acid (ATRA) did not. PA and DHA treatment increased the levels of retinyl esters (REs) in both PrECs and PC-3 cells and generated novel REs that eluted on reverse-phase HPLC at 54.0 and 50.5 min, respectively. Mass spectrometric analyses demonstrated that these novel REs were retinyl phytanate (54.0 min) and retinyl docosahexaenoate (50.5 min). Neither PA nor DHA increased LRAT mRNA levels in these cells. In addition, we demonstrate that retinyl phytanate was generated by LRAT in the presence of PA and retinol; however, retinyl docosahexaenoate was produced by another enzyme in the presence of DHA and retinol.

Cell Division↗