Protein-Mediated Fatty Acid Uptake: Novel Insights from In Vivo Models

Physiology ◽  
2006 ◽  
Vol 21 (4) ◽  
pp. 259-268 ◽  
Author(s):  
Holger Doege ◽  
Andreas Stahl

Long-chain fatty acids are both important metabolites as well as signaling molecules. Fatty acid transport proteins are key mediators of cellular fatty acid uptake and recent transgenic and knockout animal models have provided new insights into their contribution to energy homeostasis and to pathological processes, including obesity and insulin desensitization.

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Charlotte H. Hulme ◽  
Anna Nicolaou ◽  
Sharon A. Murphy ◽  
Alexander E. P. Heazell ◽  
Jenny E. Myers ◽  
...  

Abstract Diabetes mellitus (DM) during pregnancy can result in fetal overgrowth, likely due to placental dysfunction, which has health consequences for the infant. Here we test our prediction from previous work using a placental cell line that high glucose concentrations affect placental lipid metabolism. Placentas from women with type 1 (n = 13), type 2 (n = 6) or gestational (n = 12) DM, BMI-matched to mothers without DM (n = 18), were analysed for lipase and fatty acid transport proteins and fatty acid and triglyceride content. Explants from uncomplicated pregnancies (n = 6) cultured in physiological or high glucose were similarly analysed. High glucose levels did not alter placental lipase or transporter expression or the profile and abundance of fatty acids, but triglyceride levels were higher (p < 0.05), suggesting reduced β- oxidation. DM did not affect placental protein expression or fatty acid profile. Triglyceride levels of placentas from mothers with pre-existing DM were similar to controls, but higher in obese women with gestational DM. Maternal hyperglycemia may not affect placental fatty acid uptake and transport. However, placental β-oxidation is affected by high glucose and reduced in a subset of women with DM. Abnormal placental lipid metabolism could contribute to increased maternal-fetal lipid transfer and excess fetal growth in some DM pregnancies.


2000 ◽  
Vol 25 (5) ◽  
pp. 353-412 ◽  
Author(s):  
Joost J.F.P. Luiken ◽  
Jan F.C. Glatz ◽  
Arend Bonen

In view of the importance of long chain fatty acids (LCFAs) to many cellular processes, it may be desirable to regulate the LCFA disposition in the cell. Such regulation may be present at the level of the plasma membrane, since a number of putative LCFA transport proteins have been cloned. The development of a model system of giant vesicles has proven to be important in identifying the metabolic role of the LCFA transport system. LCFA transport rates and transporters (FABPpm and FAT/CD36) are scaled with oxidative capacity of heart and muscle. FAT/CD36 is a critical LCFA transport protein in muscle. With chronic contraction the increase in this protein also results in an increase in LCFA transport. Most importantly, LCFA transport is also increased acutely by muscle contraction, involving the translocation of FAT/CD36 from intracellular depots to the surface of the muscle cell. The acute (minutes) and chronic (days) regulation of LCFA transporters and transport by muscle may be an important mechanism for LCFA utilization during exercise and adaptable with training and with a metabolic disease such as type 2 diabetes. Key words: FAT/CD36, FABPpm, giant vesicles, transport


Endocrinology ◽  
2009 ◽  
Vol 150 (12) ◽  
pp. 5639-5648 ◽  
Author(s):  
Lars P. Klieverik ◽  
Claudia P. Coomans ◽  
Erik Endert ◽  
Hans P. Sauerwein ◽  
Louis M. Havekes ◽  
...  

2006 ◽  
Vol 26 (9) ◽  
pp. 3455-3467 ◽  
Author(s):  
Qiwei Wu ◽  
Angelica M. Ortegon ◽  
Bernice Tsang ◽  
Holger Doege ◽  
Kenneth R. Feingold ◽  
...  

ABSTRACT Fatty acid transport protein 1 (FATP1), a member of the FATP/Slc27 protein family, enhances the cellular uptake of long-chain fatty acids (LCFAs) and is expressed in several insulin-sensitive tissues. In adipocytes and skeletal muscle, FATP1 translocates from an intracellular compartment to the plasma membrane in response to insulin. Here we show that insulin-stimulated fatty acid uptake is completely abolished in FATP1-null adipocytes and greatly reduced in skeletal muscle of FATP1-knockout animals while basal LCFA uptake by both tissues was unaffected. Moreover, loss of FATP1 function altered regulation of postprandial serum LCFA, causing a redistribution of lipids from adipocyte tissue and muscle to the liver, and led to a complete protection from diet-induced obesity and insulin desensitization. This is the first in vivo evidence that insulin can regulate the uptake of LCFA by tissues via FATP1 activation and that FATPs determine the tissue distribution of dietary lipids. The strong protection against diet-induced obesity and insulin desensitization observed in FATP1-null animals suggests FATP1 as a novel antidiabetic target.


Nutrients ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 722 ◽  
Author(s):  
Zhibo Gai ◽  
Tianqi Wang ◽  
Michele Visentin ◽  
Gerd Kullak-Ublick ◽  
Xianjun Fu ◽  
...  

Obesity and hyperlipidemia are the most prevalent independent risk factors of chronic kidney disease (CKD), suggesting that lipid accumulation in the renal parenchyma is detrimental to renal function. Non-esterified fatty acids (also known as free fatty acids, FFA) are especially harmful to the kidneys. A concerted, increased FFA uptake due to high fat diets, overexpression of fatty acid uptake systems such as the CD36 scavenger receptor and the fatty acid transport proteins, and a reduced β-oxidation rate underlie the intracellular lipid accumulation in non-adipose tissues. FFAs in excess can damage podocytes, proximal tubular epithelial cells and the tubulointerstitial tissue through various mechanisms, in particular by boosting the production of reactive oxygen species (ROS) and lipid peroxidation, promoting mitochondrial damage and tissue inflammation, which result in glomerular and tubular lesions. Not all lipids are bad for the kidneys: polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) seem to help lag the progression of chronic kidney disease (CKD). Lifestyle interventions, especially dietary adjustments, and lipid-lowering drugs can contribute to improve the clinical outcome of patients with CKD.


1996 ◽  
Vol 271 (6) ◽  
pp. G1067-G1073
Author(s):  
C. Elsing ◽  
A. Kassner ◽  
W. Stremmel

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.


2020 ◽  
Vol 79 (OCE2) ◽  
Author(s):  
Mirko Marino ◽  
Massimiliano Tucci ◽  
Valentina Taverniti ◽  
Patrizia Riso ◽  
Marisa Porrini ◽  
...  

AbstractPolyphenols are bioactive molecules widely distributed in numerous foods such as fruits, vegetables, tea, coffee, cocoa and beverages. Their main classification include flavonoids (i.e. flavonols, flavones, flavanones, flavanols, anthocyanins, and isoflavones), non-flavonoids (i.e. lignans and stilbens) and phenolic acids (i.e. hydroxycinnamic and hydroxybenzoic acids)(1). Caffeic acid (CA) and chlorogenic acid (CGA; an ester of CA and quinic acid) are the major representatives of hydroxycinnamic acids. Accumulating evidence has demonstrated that CA and CGA may exert different biological activities, including antioxidant, anti-inflammatory, antidiabetic, and antihypertensive(2). Despite these promising and diverse anti-atherosclerotic actions, investigations addressing the effect of CA and CGA on atherogenesis are scarce.The present study evaluated the capacity of CA and CGA to reduce lipid accumulation in macrophages derived from monocytic THP-1 cells. THP-1-derived macrophages were incubated with fatty acids (500 μM oleic/palmitic acid, 2:1 ratio) and different concentrations (from 0.03 to 3 μM) of CA and CGA, alone or in combination. Lipid accumulation was quantified spectrophotometrically (excitation: 544 nm, emission: 590 nm) with the fluorescent dye, Nile red. The fold increase compared to the control (without fatty acids) was calculated. In addition, the expression of several transcription factors including peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein (CEBP), as potential mechanisms involved in the regulation of lipid accumulation, was evaluated by real time PCR.Analysis of variance (ANOVA) was used to assess the effect of the different concentrations of CA and CGA on lipid accumulation in THP-1 macrophages following stimulation with FA.The preliminary results obtained have shown a significant increase in lipid accumulation following fatty acid exposure (p < 0.0001). Incubation with CA and CGA did not reduce lipid accumulation in THP-1 derived macrophages, while the combination of CA + CGA at 0.03, 0.3 and 3 μM (p < 0.01) decreased cellular fatty acid uptake at all concentrations tested by -28%, -32%, -23%, respectively. An apparent modulation of the transcriptional activity of PPARγ, but not CEBP, was observed following the combination of phenolic acids.In conclusion, the incubation of CA + CGA at physiologically relevant concentrations, but not the single compounds, seem to reduce the uptake of fatty acids in THP-1-derived macrophages. Further experiments are ongoing in order to confirm the findings obtained and to better identify the mechanisms of action involved in the reduction of lipid accumulation as a key phenomenon of atherogenesis.


1992 ◽  
Vol 263 (3) ◽  
pp. G380-G385 ◽  
Author(s):  
D. Sorrentino ◽  
S. L. Zhou ◽  
E. Kokkotou ◽  
P. D. Berk

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.


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