scholarly journals DHHC4 and DHHC5 Facilitate Fatty Acid Uptake by Palmitoylating and Targeting CD36 to the Plasma Membrane

Cell Reports ◽  
2019 ◽  
Vol 26 (1) ◽  
pp. 209-221.e5 ◽  
Author(s):  
Juan Wang ◽  
Jian-Wei Hao ◽  
Xu Wang ◽  
Huiling Guo ◽  
Hui-Hui Sun ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Fatty Acid ◽  
Fatty Acid Uptake ◽  
Acid Uptake

Effect of surface and intracellular pH on hepatocellular fatty acid uptake

1996 ◽  
Vol 271 (6) ◽  
pp. G1067-G1073
Author(s):  
C. Elsing ◽  
A. Kassner ◽  
W. Stremmel
Keyword(s):  
Fatty Acids ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Intracellular Ph ◽  
Outer Surface ◽  
Fatty Acid Uptake ◽  
Proton Gradient ◽  
Fatty Acid Transport ◽  
Acid Uptake ◽  
Acid Transport

Fatty acids enter hepatocytes, at least in part, by a carrier-mediated uptake mechanism. The importance of driving forces for fatty acid uptake is still controversial. To evaluate possible driving mechanisms for fatty acid transport across plasma membranes, we examined the role of transmembrane proton gradients on fatty acid influx in primary cultured rat hepatocytes. After hepatocytes were loaded with SNARF-1 acetoxymethyl ester, changes in intracellular pH (pHi) under different experimental conditions were measured and recorded by confocal laser scanning microscopy. Fatty acid transport was increased by 45% during cellular alkalosis, achieved by adding 20 mM NH4Cl to the medium, and a concomitant paracellular acidification was observed. Fatty acid uptake was decreased by 30% during cellular acidosis after withdrawal of NH4Cl from the medium. Cellular acidosis activates the Na+/H+ antiporter to export excessive protons to the outer cell surface. Inhibition of Na+/H+ antiporter activity by amiloride diminishes pHi recovery and thereby accumulation of protons at the outer surface of the plasma membrane. Under these conditions, fatty acid uptake was further inhibited by 57% of control conditions. This suggests stimulation of fatty acid influx by an inwardly directed proton gradient. The accelerating effect of protons at the outer surface of the plasma membrane was confirmed by studies in which pH of the medium was varied at constant pHi. Significantly higher fatty acid influx rates were observed at low buffer pH. Recorded differences in fatty acid uptake appeared to be independent of changes in membrane potential, because BaCl2 did not influence initial uptake velocity during cellular alkalosis and paracellular acidosis. Moreover, addition of oleate-albumin mixtures to the NH4Cl incubation buffer did not change the observed intracellular alkalinization. In contrast, after cells were acid loaded, addition of oleate-albumin solutions to the recovery buffer increased pHi recovery rates from 0.21 +/- 0.02 to 0.36 +/- 0.05 pH units/min (P < 0.05), indicating that fatty acids further stimulate Na+/H+ antiporter activity during pHi recovery from an acid load. It is concluded that carrier-mediated uptake of fatty acids in hepatocytes follows an inwardly directed transmembrane proton gradient and is stimulated by the presence of H+ at the outer surface of the plasma membrane.

Fatty acid uptake in Escherichia coli: regulation by recruitment of fatty acyl-CoA synthetase to the plasma membrane

1993 ◽  
Vol 71 (1-2) ◽  
pp. 51-56 ◽  
Author(s):  
Dev Mangroo ◽  
Gerhard E. Gerber
Keyword(s):  
Escherichia Coli ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Fatty Acid Uptake ◽  
Fatty Acyl ◽  
Acid Uptake ◽  
Bacterial Membranes ◽  
Rate Limiting Step ◽  
Triton X ◽  
Rate Limiting

Fatty acid uptake in Escherichia coli has been shown to be inhibited by starvation and to be reversed by a short preincubation of the starved cells with D- or L-lactate, succinate, and acetate; these effects on oleate uptake were due to regulation of the rate-limiting step which involves fatty acyl-CoA synthetase. Investigation into the mechanism of regulation of fatty acyl-CoA synthetase showed that D-lactate did not affect the activity of the enzyme directly. Fatty acyl-CoA synthetase was found to be activated by about 20-fold by Triton X-100 and by another 4-fold by the addition of bacterial membranes. D-Lactate treatment was shown to result in coisolation of fatty acyl-CoA synthetase with the plasma membrane; these results are consistent with the interpretation that recruitment of the enzyme to the plasma membrane by D-lactate results in its activation and consequently in the increased level of fatty acid uptake.Key words: fatty acid, uptake, regulation, recruitment, fatty acyl-CoA synthetase, Escherichia coli, plasma membrane.

Sex differences in hepatic fatty acid uptake reflect a greater affinity of the transport system in females

1992 ◽  
Vol 263 (3) ◽  
pp. G380-G385 ◽  
Author(s):  
D. Sorrentino ◽  
S. L. Zhou ◽  
E. Kokkotou ◽  
P. D. Berk
Keyword(s):  
Plasma Membrane ◽  
Fatty Acid ◽  
Transport System ◽  
Fatty Acid Uptake ◽  
Surface Expression ◽  
Female Rats ◽  
Acid Uptake ◽  
Fatty Acid Binding ◽  
Male And Female Rats

In this study, we examined the hypothesis that the reported sex difference in hepatic free fatty acid (FFA) uptake involves the putative FFA transport system, the plasma membrane fatty acid binding protein (FABPpm). In hepatocytes isolated from both male and female rats, initial [3H]oleate uptake velocity reflected transmembrane influx and not subsequent metabolism and was a saturable function of the unbound oleate concentration. Although Vmax values were similar (61 +/- 2 vs. 65 +/- 5 pmol.min-1.5 x 10(4) cells-1 for females and males, respectively), the apparent Km was significantly smaller in females (40 +/- 4 vs. 90 +/- 11 nM; P less than 0.05), reflecting faster influx velocities in female cells over a range of unbound oleate concentrations. The oleate efflux rate constant was also greater in females (0.280 +/- 0.014 vs. 0.198 +/- 0.020 min-1; P less than 0.05) despite their greater hepatic content of cytosolic FABP. Finally, despite the greater rates of transmembrane FFA flux in female hepatocytes, the surface expression of FABPpm was virtually identical in the two sexes (2.5 +/- 0.5 vs. 2.4 +/- 0.4 microgram/10(6) cells). Collectively, these data indicate that at FFA-to-albumin ratios occurring in vivo the plasma membrane of female hepatocytes transports oleate bidirectionally at a greater rate than that of male hepatocytes. A sex-related difference in the functional affinity of FABPpm for FFA appears the most likely explanation for the greater oleate uptake in females.

Insulin induces the translocation of the fatty acid transporter FAT/CD36 to the plasma membrane

2002 ◽  
Vol 282 (2) ◽  
pp. E491-E495 ◽  
Author(s):  
Joost J. F. P. Luiken ◽  
David J. Dyck ◽  
Xiao-Xia Han ◽  
Narendra N. Tandon ◽  
Yoga Arumugam ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Fatty Acid ◽  
Muscle Contraction ◽  
Kinase Inhibitor ◽  
Fatty Acid Uptake ◽  
Fatty Acid Transport ◽  
Acid Uptake ◽  
Hindlimb Muscles ◽  
Fatty Acid Transporter ◽  
Acid Transporter

It is well known that muscle contraction and insulin can independently translocate GLUT-4 from an intracellular depot to the plasma membrane. Recently, we have shown that the fatty acid transporter FAT/CD36 is translocated from an intracellular depot to the plasma membrane by muscle contraction (<30 min) (Bonen et al. J Biol Chem 275: 14501–14508, 2000). In the present study, we examined whether insulin also induced the translocation of FAT/CD36 in rat skeletal muscle. In studies in perfused rat hindlimb muscles, we observed that insulin increased fatty acid uptake by +51%. Insulin increased the rate of palmitate incorporation into triacylglycerols, diacylglycerols, and phospholipids ( P < 0.05) while reducing muscle palmitate oxidation ( P < 0.05). Perfusing rat hindlimb muscles with insulin increased plasma membrane FAT/CD36 by +48% ( P < 0.05), whereas concomitantly the intracellular FAT/CD36 depot was reduced by 68% ( P < 0.05). These insulin-induced effects on FAT/CD36 translocation were inhibited by the phosphatidylinositol 3-kinase inhibitor LY-294002. Thus these studies have shown for the first time that insulin can induce the translocation of FAT/CD36 from an intracellular depot to the plasma membrane.This reveals a previously unknown level of regulation of fatty acid transport by insulin and may well have important consequences in furthering our understanding of the relation between fatty acid metabolism and insulin resistance.

Common mechanisms of monoacylglycerol and fatty acid uptake by human intestinal Caco-2 cells

2001 ◽  
Vol 281 (4) ◽  
pp. C1106-C1117 ◽  
Author(s):  
Shiu-Ying Ho ◽  
Judith Storch
Keyword(s):  
Plasma Membrane ◽  
Fatty Acid ◽  
Monomer Concentration ◽  
Protein S ◽  
Fatty Acid Uptake ◽  
Fatty Acid Transport ◽  
Acid Uptake ◽  
Fatty Acid Binding ◽  
Bound Lipids ◽  
Kinetics Of

Free fatty acids (FFA) and sn-2-monoacylglycerol ( sn-2-MG), the two hydrolysis products of dietary triacylglycerol, are absorbed from the lumen into polarized enterocytes that line the small intestine. Intensive studies regarding FFA transport across the brush-border membrane of the enterocyte are available; however, little is known about sn-2-MG transport. We therefore studied the kinetics of sn-2-MG transport, compared with those of long-chain FFA (LCFA), by human intestinal Caco-2 cells. To mimic postprandial luminal and plasma environments, we examined the uptake of taurocholate-mixed lipids and albumin-bound lipids at the apical (AP) and basolateral (BL) surfaces of Caco-2 cells, respectively. The results demonstrate that the uptake of sn-2-monoolein at both the AP and BL membranes appears to be a saturable function of the monomer concentration of sn-2-monoolein. Furthermore, trypsin preincubation inhibits sn-2-monoolein uptake at both AP and BL poles of cells. These results suggest that sn-2-monoolein uptake may be a protein-mediated process. Competition studies also support a protein-mediated mechanism and indicate that LCFA and LCMG may compete through the same membrane protein(s) at the AP surface of Caco-2 cells. The plasma membrane fatty acid-binding protein (FABPpm) is known to be expressed in Caco-2, and here we demonstrate that fatty acid transport protein (FATP) is also expressed. These putative plasma membrane LCFA transporters may be involved in the uptake of sn-2-monoolein into Caco-2 cells.

Fatty acid transport and metabolism in HepG2 cells

2006 ◽  
Vol 290 (3) ◽  
pp. G528-G534 ◽  
Author(s):  
Wen Guo ◽  
Nasi Huang ◽  
Jun Cai ◽  
Weisheng Xie ◽  
James A. Hamilton
Keyword(s):  
Fatty Acids ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Hepg2 Cells ◽  
Fatty Acid Uptake ◽  
Metabolic Inhibitors ◽  
Fatty Acid Transport ◽  
Acid Uptake ◽  
Triacsin C ◽  
Membrane Bound

The mechanism(s) of fatty acid uptake by liver cells is not fully understood. We applied new approaches to address long-standing controversies of fatty acid uptake and to distinguish diffusion and protein-based mechanisms. Using HepG2 cells containing an entrapped pH-sensing fluorescence dye, we showed that the addition of oleate (unbound or bound to cyclodextrin) to the external buffer caused a rapid (seconds) and dose-dependent decrease in intracellular pH (pHin), indicating diffusion of fatty acids across the plasma membrane. pHin returned to its initial value with a time course (in min) that paralleled the metabolism of radiolabeled oleate. Preincubation of cells with the inhibitors phloretin or triacsin C had no effect on the rapid pHin drop after the addition of oleate but greatly suppressed pHin recovery. Using radiolabeled oleate, we showed that its esterification was almost completely inhibited by phloretin or triacsin C, supporting the correlation between pHin recovery and metabolism. We then used a dual-fluorescence assay to study the interaction between HepG2 cells and cis-parinaric acid (PA), a naturally fluorescent but slowly metabolized fatty acid. The fluorescence of PA increased rapidly upon its addition to cells, indicating rapid binding to the plasma membrane; pHin decreased rapidly and simultaneously but did not recover within 5 min. Phloretin had no effect on the PA-mediated pHin drop or its slow recovery but decreased the absolute fluorescence of membrane-bound PA. Our results show that natural fatty acids rapidly bind to, and diffuse through, the plasma membrane without hindrance by metabolic inhibitors or by an inhibitor of putative membrane-bound fatty acid transporters.

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