Showing papers on "Fatty acid-binding protein published in 2003"

Cytoplasmic fatty acid-binding protein facilitates fatty acid utilization by skeletal muscle

Abstract: The intracellular transport of long-chain fatty acids in muscle cells is facilitated to a great extent by heart-type cytoplasmic fatty acid-binding protein (H-FABP). By virtue of the marked affinity of this 14.5-kDa protein for fatty acids, H-FABP dramatically increases their concentration in the aqueous cytoplasm by non-covalent binding, thereby facilitating both the transition of fatty acids from membranes to the aqueous space and their diffusional transport from membranes (e.g. sarcolemma) to other cellular compartments (e.g. mitochondria). Striking features are the relative abundance of H-FABP in muscle, especially in oxidative muscle fibres, and the modulation of the muscular H-FABP content in concert with the modulation of other proteins and enzymes involved in fatty acid handling and utilization. Newer studies with mice carrying a homozygous or heterozygous deletion of the H-FABP gene show that, in comparison with wild-type mice, hindlimb muscles from heterozygous animals have a markedly lowered (-66%) H-FABP content but unaltered palmitate uptake rate, while in hindlimb muscles from homozygous animals (no H-FABP present) palmitate uptake was reduced by 45%. These findings indicate that H-FABP is present in relative excess and plays a substantial, but merely permissive role in fatty acid uptake by skeletal muscles.

In vitro inhibition of insulin-degrading enzyme by long-chain fatty acids and their coenzyme A thioesters.

Abstract: Insulin-degrading enzyme is responsible for initiating insulin degradation in cells, but little is known about the factors controlling its activity. Because obesity and high levels of free fatty acids decrease insulin clearance, we examined the effect of some common free fatty acids and their acyl-coenzyme A thioesters on insulin-degrading enzyme partially purified from the livers of male Sprague Dawley rats. Octanoic acid (C8:0) had no effect on activity. Long-chain free fatty acids (C16-C20) inhibited between 50% and 90% of the insulin degradation with IC(50) values in the range of 10-50 micro M. In general, the corresponding acyl-coenzyme A thioesters had lower IC(50) values and were slightly more efficacious. (125)I-insulin cross-linking studies showed free fatty acids did not inhibit hormone binding to insulin-degrading enzyme. Kinetic analysis showed a noncompetitive type of inhibition. Furthermore, fatty acids eliminated the ability of insulin to inhibit the proteasome. These results suggest that when intracellular long-chain fatty acid concentrations are elevated, they may act directly on insulin-degrading enzyme to decrease insulin metabolism and alter insulin action in intact cells. This mechanism may contribute to the hyperinsulinemia and insulin resistance seen with elevated fatty acids and obesity.

Plasmalemmal fatty acid transport is regulated in heart and skeletal muscle by contraction, insulin and leptin, and in obesity and diabetes.

Abstract: It has been assumed that the uptake of long chain fatty acids (LCFAs) into skeletal muscle and the heart muscle, as well as other tissues, occurred via passive diffusion. In recent years our work has shown that the LCFA uptake into skeletal muscle is a highly regulated process. The use of giant sarcolemmal vesicles obtained from skeletal muscle and heart has been used to demonstrate that LCFA uptake into these tissues occurs via a protein-mediated mechanism involving the 40 kDa plasma membrane associated fatty acid binding protein (FABPpm) and the 88 kDa fatty acid translocase, the homologue of human CD36 (FAT/CD36). Both are ubiquitously expressed proteins and correlate with LCFA uptake into heart and muscle, consistent with the known differences in LCFA metabolism in these tissues. It has recently been found that FAT/CD36 is present in an intracellular (endosomal) compartment from which it can be translocated to the plasma membrane within minutes by muscle contraction and by insulin, to stimulate LCFA uptake. In rodent models of obesity and type 1 diabetes LCFA uptake into heart and muscle is also increased, either by permanently relocating FAT/CD36 to the plasma membrane without altering its expression (obesity) or by increasing the expression of both FAT/CD36 and FABPpm (type 1 diabetes). Chronic leptin treatment decreases LCFA transporters and transport in muscle. Clearly, recent evidence has established that LCFA uptake into heart and muscle is regulated acutely and chronically.

Differential subcellular localization of two dopamine D2 receptor isoforms in transfected NG108‐15 cells

Abstract: The dopamine D2 receptor (D2R) is target for antipsychotic drugs and associated with several neuropsychiatric disorders D2R has a long third cytoplasmic loop and a short carboxyl-terminal cytoplasmic tail It exists as two alternatively spliced isoforms, termed D2LR and D2SR, which differ in the presence and absence, respectively, of a 29 amino acid insert in the third cytoplasmic loop To evaluate the differential roles of the two D2R isoforms, we transfected both isoforms into NG108-15 cells and observed their subcellular localization by a confocal laser scanning light microscope D2SR was predominantly localized at the plasma membrane, whereas D2LR was mostly retained in the perinuclear region around the Golgi apparatus Using a yeast two hybrid system with a mouse brain cDNA library and coimmunoprecipitation assay, we found that heart-type fatty acid binding protein (H-FABP) interacts with D2LR but not with D2SR H-FABP is a cytosolic protein involved in binding and transport of fatty acids Overexpressed H-FABP and endogenous H-FABP were colocalized with the intracellular D2LR in NG108-15 cells Furthermore, in the rat striatum, H-FABP was detected in the D2R-expressing neurons From these results, H-FABP is associated with D2LR, and may thereby modulate the subcellular localization and function of D2LR

Interactions of Surfactant Protein D with Fatty Acids

Abstract: Surfactant Protein D (SP-D) plays important roles in antimicrobial host defense, inflammatory and immune regulation, and pulmonary surfactant homeostasis. The best-characterized endogenous ligand is phosphatidylinositol; however, this lipid interaction at least in part involves the carbohydrate moiety. In this study we observed that SP-D binds specifically to saturated, unsaturated, and hydroxylated fatty acids (FA). Binding of biotinylated-SP-D to FAs or biotinylated FA to SP-D was dose-dependent, saturable, and specifically competed by the corresponding unlabeled probe. Specific binding to FA chains was also demonstrated by solution phase competition for FA binding to acrylodan-labeled FA binding protein (ADIFAB), and by overlay of thin layer chromatograms with SP-D. Maximal binding to FA was dependent on calcium, and binding was localized to the neck and carbohydrate recognition domains (CRD) using recombinant trimeric neck+CRDs. Saccharide ligands showed complex, dose-dependent effects on FA binding, and FAs showed dose- and physical state-dependent effects on the binding of SP-D to mannan. In addition, CD spectroscopy suggested alterations in SP-D structure associated with binding to monomeric FA. Together, the findings indicate specific binding of FA to one or more sites in the CRD. We speculate that the binding of SP-D to the fatty acyl chains of surfactant lipids, microbial ligands, or other complex lipids contributes to the diverse biological functions of SP-D in vivo.

A null mutation in H-FABP only partially inhibits skeletal muscle fatty acid metabolism

Abstract: The low-molecular-mass, cytosolic heart-type fatty acid-binding protein (H-FABP) is thought to be required for shuttling FA through the cytosol. Therefore, we examined the effects of an H-FABP-null...

Heart type fatty acid binding protein (H-FABP) is decreased in brains of patients with Down syndrome and Alzheimer's disease.

Abstract: Fatty acid binding proteins (FABPs) are thought to play a role in the binding, targeting and transport of long-chain fatty acids, and at least three types of FABPs are found in human brain; heart type (H)-FABP, brain type (B)-FABP and epidermal type (E)-FABP. Although all three FABPs could be involved in normal brain function in prenatal and postnatal life, a neurobiological role of FABPs in neurodegenerative diseases has not been reported yet. These made us evaluate the protein levels of FABPs in brains from patients with Down syndrome (DS) and Alzheimer’s disease (AD) and fetal cerebral cortex with DS using two-dimensional (2-D) gel electrophoresis with subsequent matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS) identification and specific software for quantification of proteins. In adult brain, B-FABP was significantly increased in occipital cortex of DS, and H-FABP was significantly decreased in DS (frontal, occipital and parietal cortices) and AD (frontal, temporal, occipital and parietal cortices). In fetal brain, B-FABP and epidermal E-FABP levels were comparable in controls and DS. We conclude that aberrant expression of FABPs, especially H-FABP may alter membrane fluidity and signal transduction, and consequently could be involved in cellular dysfunction in neurodegenerative disorders.

Variation in the FABP2 promoter alters transcriptional activity and is associated with body composition and plasma lipid levels

Abstract: The fatty acid-binding proteins (FABPs) are cytoplasmic proteins involved in intracellular fatty acid transport and metabolism. FABP2, the intestinal-type FABP, is expressed exclusively in enterocytes in the small intestine. In previous studies of an Ala54Thr substitution in FABP2, the Thr-allele showed association with increased lipid oxidation, elevated plasma lipids, and impaired insulin sensitivity. We screened roughly 1 kb 5' of the FABP2 initiation codon and identified three insertion/deletion polymorphisms and four single nucleotide polymorphisms (SNPs). Three of the SNPs were in complete linkage disequilibrium with the three insertion/deletion polymorphisms, defining exactly two haplotypes (FABP2p-ID). We tested the hypothesis that this variation alters gene expression by transfecting Caco-2 cells with pGL3-Basic constructs containing opposite FABP2p-ID haplotypes. Luciferase assays showed a statistically significant two-fold increase in gene expression of the pGL3-insertion construct over the pGL3-deletion construct (P<0.001; n=5). We also tested for association between three FABP2 variants and measurements of body composition, plasma lipids, and insulin sensitivity in non-diabetic control subjects from the San Luis Valley Diabetes Study (n=714). The only informative variant, FABP2p-ID, was statistically significantly associated with body mass index (P=0.042) and marginally associated with fat mass (P=0.084), cholesterol (P=0.066), and HOMA IR (a derived measure of insulin resistance; P=0.062) in the entire cohort. Similar associations were seen only in non-Hispanics when the analysis was stratified by ethnicity. Within the non-Hispanic subgroup, the effects of FABP2p-ID on plasma lipids were sex-specific. These results suggest that genetic variation in the 5' region of FABP2 affects transcriptional activity, presumably leading to alterations in body composition and lipid processing.

Cellular proteins and their fatty acids in health and disease

Abstract: Preface.List of Contributors.PART 1 - THE MOLECULAR BASIS OF PROTEIN-LIPID INTERACTION AND FUNCTIONAL CONSEQUENCES.1. Structure-Function of CD36 and Evidence for its Role in Facilitating Membrane Fatty Acid Transport (C. Coburn & N. Abumrad).2. Role and Function of FATPs in Fatty Acid Uptake (J. Schaffer).3. Function, Expression, and Regulation of Human ABC Transporters (G. Schmitz & T. Langmann).4. Albumin Receptors - Structure and Function (N. Brunskill).5. Intracellular Lipid Binding Proteins: Evolution, Structure, and Ligand Binding (C. Lucke, et al.).6. Fatty Acid Binding Proteins and Fatty Acid Transport (J. Storch & L. McDermott).7. Structure and Function of SCP-x/SCP-2 (U. Seedorf).8. Structure, Function, and Phylogeny of Acyl-CoA Binding Protein (S. Mandrup, et al.).9. Structure and Function of PPARs and their Molecular Recognition of Fatty Acids (C. Palmer).10. Structure and Function of Retinoid Receptors RAR and RXR (A. Mata de Urquiza & T. Perlmann).11. Liver X Receptors (LXRs) - Important Regulators of Lipid Homeostasis (L. Juvet & H. Nebb).12. Acyl-CoA Ligands of HNF-4a and HNF-4a/PPARa Interplay (R. Hertz & J. Bar-Tana).PART 2 - ROLE FOR PROTEINS IN CELLULAR HOMEOSTASIS.13. Fatty Acid Binding Proteins and their Roles in Transport of Long-chain Polyunsaturated Fatty Acids across the Feto-placental Unit (A. Duttaroy).14. Fatty Acid Binding Proteins of the Brain (Y. Owada & H. Kondo).15. Cross-talk between Intracellular Lipid Binding Proteins and Ligand Activated Nuclear Receptors - A Signaling Pathway for Fatty Acids (C. Wolfrum & F. Spener).16. Arachidonic Acid Binding Proteins in Human Neutrophils (C. Kerkhoff & O. Radmark).17. PPARs, Cell Differentiation, and Glucose Homeostasis (S. Farmer).18. Role of FABPs in Cellular Phospholipid Metabolism (C. Jolly & E. Murphy).19. Membrane-associated Fatty Acid Binding Proteins Regulate Fatty Acid Uptake by Cardiac and Skeletal Muscle (J. Glatz, et al.).20. Intestinal Fat Absorption: Roles of Intracellular Lipid-Binding Proteins and Peroxisome Proliferator-Activated Receptors (I. Niot & P. Besnard).21. Fatty Acid Binding Proteins as Metabolic Regulators (J. Stewart).22. Role of Lipid Binding Proteins in Disease (A. Meirhaeghe & P. Amouyel).23. PPARs and Atherosclerosis (J. Plutzky).24. PPARs: Nuclear Hormone Receptors Involved in the Control of Inflammation (L. Michalik, et al.).25. PPARs and Cancer (J. Gill & R. Roberts).Subject Index.

Localization of brain-type fatty acid-binding protein in Kupffer cells of mice and its transient decrease in response to lipopolysaccharide

Abstract: Brain-type fatty acid-binding protein (B-FABP) was localized in Kupffer cells of liver of postnatal day 10 (P10) and older mice in immunolight and electron microscopy as well as by in situ hybridization histochemistry. The immunoreaction products were localized in the cytoplasmic matrix but not within the nucleus. After peritoneal injection of lipopolysaccharide (LPS), the immunoreaction for B-FABP decreased markedly in Kupffer cells at 1 h postinjection and thereafter gradually recovered to the preinjection level by 24 h postinjection, although no decrease in the mRNA expression was detected in Northern blotting throughout the course after the injection. The specific localization of B-FABP, but not the other FABPs, in Kupffer cells, and its rapid decrease after LPS injection suggest the intimate involvement of B-FABP in Kupffer cells in the inflammatory reaction, probably through mediation of n-3 polyunsaturated fatty acids, which are strong binders of B-FABP.

Properties and physiological significance of fatty acid binding proteins

Abstract: Publisher Summary This chapter discusses the properties and physiological significance of fatty acid binding properties. Fatty acid binding proteins (FABP) are found in many tissues of many different organisms, which include mammals, fish, birds, and insects. All FABPs are members of a large multigene family called intracellular lipid binding proteins (iLBPs) with various functions in the transport and metabolism of their ligand fatty acids and other lipophilic ligands. There are different roles in different cells, tissues, and organisms may vary, common features become apparent in the context of metabolic tasks and conditions. The purpose of this chapter is to summarize current knowledge about these proteins, and to provide insight into their roles in different organisms. FABPs are expressed in vertebrate and invertebrate species. Pertaining to the latter, two FABPs are expressed in the midgut of the tobacco hornworm and believed to be involved in lipid digestion. The FABP from the flight muscle of locusts is especially well characterized. The chapter also explains structure and conformation of FABPs and their ligands.

Solution structure of human intestinal fatty acid binding protein with a naturally-occurring single amino acid substitution (A54T) that is associated with altered lipid metabolism.

Abstract: The human intestinal fatty acid binding protein (I-FABP) belongs to a family of intracellular lipid binding proteins. This 15 kDa protein binds dietary long-chain fatty acids in the cytosol of enterocytes. A naturally-occurring nucleotide polymorphism at codon 54, which produces either an alanine-containing (A54) or a threonine-containing (T54) protein, has been identified. These two I-FABP forms display differential binding and transport of fatty acids across cells, and their alleles are associated with in vivo insulin resistance and/or altered lipid metabolism in several human populations. The three-dimensional solution structure of the more common A54 form was previously determined in our lab. A direct comparison between human A54 and T54 I-FABP has now been performed to help elucidate the structural origins of their physiological distinctions. The solution structure of T54 I-FABP is highly homologous to that of A54 I-FABP, with the same overall three-dimensional fold that includes an antiparallel beta-clam motif. Chemical shift differences between the two proteins suggest only minor local structural changes within the "portal region" and no significant alterations elsewhere. Hence, the slightly stronger binding of fatty acids to T54 I-FABP does not originate from residues in direct contact with the bound fatty acid. Instead, it appears that the larger Thr(54) side chain affects the passage of the ligand through the entry portal. Structural details of this portal region will be discussed in view of the influence residue 54 exerts on the functional properties of human I-FABP.

Urinary fatty acid binding protein as a new clinical marker for the progression of chronic renal disease

Abstract: BACKGROUND As free fatty acids are loaded into the proximal tubule during various kinds of stresses and become cytotoxic, they may play an important role in the progression of renal disease. The proximal tubular epithelial cells express liver-type fatty acid binding protein(L-FABP), an intracellular carrier protein of fatty acids. We hypothesized that urinary L-FABP reflected stresses on the proximal tubule and thus presents a new clinical marker for the progression of renal disease. METHODS ELISA for L-FABP was established and relations between urinary L-FABP and clinical parameters from non-diabetic chronic renal disease (n = 120) were evaluated. RESULTS Laboratory data revealed a correlation between urinary L-FABP and urinary protein (F = 22.7), urinary alpha 1-microglobulin (F = 13.9) and serum creatinine (F = 11.4). Notably only urinary L-FABP at the start of follow-up (F = 17.1) was selected as a significant clinical factor correlated with the progression rate defined as a slope of a reciprocal of serum creatinine over time. The results indicated that urinary L-FABP was correlated with the clinical prognosis of renal disease. CONCLUSION Urinary L-FABP is a new clinical marker for predicting the progression of chronic glomerular disease.

Fatty acid binding protein is a major determinant of hepatic pharmacokinetics of palmitate and its metabolites.

Abstract: Disposition kinetics of [3H]palmitate and its low-molecular-weight metabolites in perfused rat livers were studied using the multiple-indicator dilution technique, a selective assay for [3H]palmita...

Solution structure of chicken liver basic fatty acid binding protein.

Abstract: Chicken liver basic fatty acid binding protein (Lb-FABP) belongs to the basic-type fatty acid binding proteins, a novel group of proteins isolated from liver of different non mammalian species whose structure is not known. The structure of Lb-FABP has been solved by 1H NMR. The overall fold of Lb-FABP, common to the other proteins of the family, consists of ten antiparallel β-strands organised in two nearly ortogonal β-sheets with two alpha helices closing the protein cavity where small hydrophobic ligands can be bound. The binding specificity of the protein is not known, however, based on the high sequence and structural similarity with an orthologous protein, ileal lipid binding protein, it is suggested that bile acids may be the putative ligands.

Induction of epidermal fatty acid binding protein in intravascular monocytes of renal allografts.

Abstract: During acute rejection of rat renal allografts, numerous activated monocytes accumulate in the vasculature of the graft. These monocytes seem to be involved in allograft destruction. Proinflammatory and effector functions of monocytes and macrophages can be down-regulated by peroxisome proliferators, which are probably transported in the cytoplasm by fatty acid binding proteins (FABPs). We performed renal transplantation in rats in the Dark Agouti-to-Lewis strain combination. Intravascular graft leukocytes were harvested 4 days posttransplantation. Epidermal (E)-FABP mRNA and protein expression were investigated by reverse-transcriptase polymerase chain reaction and immunoblotting, respectively. E-FABP-expressing cells were identified by immunofluorescence. After allogeneic transplantation, intravascular graft leukocytes expressed E-FABP mRNA and protein. In isografts, significantly lower expression levels were observed. E-FABP protein was detected in monocytes expressing ED1 and in αβ-T-cell receptor positive T lymphocytes. E-FABP might regulate monocyte activation and may represent a promising target for a therapeutic intervention in allograft rejection.

Fatty acids bound to Fasciola hepatica 12 kDa fatty acid-binding protein, a candidate vaccine, differ from fatty acids in extracts of adult flukes

Abstract: The FA composition of Fasciola hepatica 12 kDA purified native FA-binding protein (nFh12), a candidate vaccine against fascioliasis, is described. The FA chain lengths ranged between 12 and 24 carbons. The principal FA were 16∶0 18∶1n−9, 18∶0, 20∶4n−6, and 20∶1n−9. The acids 16∶0, 18∶1n−9, and 18∶0 comprised over half the FA that were bound to the whole FA-binding protein. Small amounts (1.0–2.8%) of isoanteiso methyl-branched FA also were characterized. Forty-one different FA were identified in extracts of the adult flukes, with the three most abundant FA also being 16∶0, 18∶1n−9, and 18∶0. A similar proportion of saturated vs. unsaturated FA was observed between the whole extract from F. hepatica and the nFh12 protein. However, the n−3/n−6 ratio of PUFA was significantly different, being 1.2 in the whole extract vs. 9.6 in the nFh12 protein complex. The nFh12 protein binds more n−5, n−6, and n−7 PUFA and less n−3 and n−9 PUFA than the whole extract. In addition, cholesterol (56%), sitosterol (36%), and fucosterol (8%) also were bound to the nFh12 protein complex.

Short communication Fatty acid release and oxidation are factors in lipoxygenase inhibitor-induced apoptosis

Abstract: MK886, an inhibitor of 5-lipoxygenase activating protein (FLAP), and the lipoxygenase (LOX) inhibitors baicalein and nordihydroguaiaretic acid (NDGA), induce apoptosis by mechanisms independent of both LOX and FLAP One possible mechanism for these agents is through an effect on the binding of fatty acids to LOX and fatty acid binding proteins resulting in increased intracellular levels of unbound fatty acids, particularly arachidonic acid (AA), that in turn, activate apoptosis signaling pathways either directly or following oxidation In FL512 murine pro-B lymphocytic cells, exogenous fatty acids induced apoptosis proportional to their degree of unsaturation MK886, baicalein, and NDGA significantly enhanced the release of [ 3 H]-AA two to threefold within 2 h and induced apoptosis by 8 h Neither MK886-induced AA release, nor apoptosis were affected by quinacrine, a phospholipase A2 inhibitor The presence of peroxides 1 h after treatment of FL512 cells with these agents was evident by a two to threefold increase in the ferrous oxidation � /xylenol orange (FOX) assay as well as dichlorofluorescein fluorescence measured with flow cytometry Isoprostane formation, an additional index of lipid peroxidation, was increased threefold by 2 h, and fourfold at 4 h after MK886 or baicalein, but not after NDGA Antioxidants were able to protect against NDGA-induced apoptosis but had no effect on baicalein and resulted in enhanced apoptosis with MK886 These data support the hypothesis that release of fatty acids and generation of oxidized species contribute to apoptosis induced by these LOX inhibitors, but that more complex mechanisms are likely involved # 2002 Elsevier Science Ireland Ltd All rights reserved