Fatty acid-binding protein

About: Fatty acid-binding protein is a research topic. Over the lifetime, 1721 publications have been published within this topic receiving 81530 citations. The topic is also known as: FABP.

Characterization of 4-HNE Modified L-FABP Reveals Alterations in Structural and Functional Dynamics

Abstract: 4-Hydroxynonenal (4-HNE) is a reactive α,β-unsaturated aldehyde produced during oxidative stress and subsequent lipid peroxidation of polyunsaturated fatty acids. The reactivity of 4-HNE towards DNA and nucleophilic amino acids has been well established. In this report, using proteomic approaches, liver fatty acid-binding protein (L-FABP) is identified as a target for modification by 4-HNE. This lipid binding protein mediates the uptake and trafficking of hydrophobic ligands throughout cellular compartments. Ethanol caused a significant decrease in L-FABP protein (P<0.001) and mRNA (P<0.05), as well as increased poly-ubiquitinated L-FABP (P<0.001). Sites of 4-HNE adduction on mouse recombinant L-FABP were mapped using MALDI-TOF/TOF mass spectrometry on apo (Lys57 and Cys69) and holo (Lys6, Lys31, His43, Lys46, Lys57 and Cys69) L-FABP. The impact of 4-HNE adduction was found to occur in a concentration-dependent manner; affinity for the fluorescent ligand, anilinonaphthalene-8-sulfonic acid, was reduced from 0.347 µM to Kd1 = 0.395 µM and Kd2 = 34.20 µM. Saturation analyses revealed that capacity for ligand is reduced by approximately 50% when adducted by 4-HNE. Thermal stability curves of apo L-FABP was also found to be significantly affected by 4-HNE adduction (ΔTm = 5.44°C, P<0.01). Computational-based molecular modeling simulations of adducted protein revealed minor conformational changes in global protein structure of apo and holo L-FABP while more apparent differences were observed within the internal binding pocket, revealing reduced area and structural integrity. New solvent accessible portals on the periphery of the protein were observed following 4-HNE modification in both the apo and holo state, suggesting an adaptive response to carbonylation. The results from this study detail the dynamic process associated with L-FABP modification by 4-HNE and provide insight as to how alterations in structural integrity and ligand binding may a contributing factor in the pathogenesis of ALD.

Specific growth stimulation by linoleic acid in hepatoma cell lines transfected with the target protein of a liver carcinogen.

Abstract: The hepatic carcinogen N-2-fluorenylacetamide (2-acetylaminofluorene) was shown previously to interact specifically with its target protein, liver fatty acid binding protein (L-FABP), early during hepatocarcinogenesis in rats. In search of the significance of the interaction, rat L-FABP cDNA in the sense and antisense orientations was transfected into a subline of the rat hepatoma HTC cell line that did not express L-FABP. After the transfections, the basal doubling times of the cells were not significantly different. However, at 10(-5)-10(-7) M, linoleic acid, which is an essential fatty acid, a ligand of L-FABP, and the precursor of many eicosanoids and related lipids, stimulated the incorporation of [3H]thymidine in three randomly isolated and stably transfected cell clones that expressed L-FABP, but virtually did not stimulate the incorporation of [3H]thymidine in three L-FABP-nonexpressing clones transfected with the antisense DNA. Linoleic acid at 10(-6) M increased cell number almost 3-fold (38% vs. 14%; P less than 0.0001) and thymidine incorporation nearly 5-fold (23.2% vs. 4.9%; P less than 0.001) in the L-FABP-expressing cells compared to that in the transfected nonexpressing cells. L-FABP acted specifically and cooperatively with linoleic acid, inasmuch as all the proteins other than L-FABP in the transfected L-FABP nonexpressing cells and four other fatty acids (gamma-linolenic acid, dihomo-gamma-linolenic acid, arachidonic acid, and palmitoleic acid) were unable to effect a significant elevation or difference in the level of DNA synthesis that was attributable to the transfection. Metabolism of the linoleic acid to oxygenated derivatives was apparently necessary, since the cyclooxygenase inhibitor indomethacin partly inhibited and the antioxidant lipoxygenase inhibitors nordihydroguariaretic acid and alpha-tocopherol completely abolished the growth stimulation. The evidence supports the idea that L-FABP, the target protein of the liver carcinogen, acts specifically in concert with oxygenated metabolites of linoleic acid to modulate the growth of hepatocytes.

Inhibition of FASN reduces the synthesis of medium-chain fatty acids in goat mammary gland.

Abstract: Fatty acid synthase (FASN) is known as a crucial enzyme of cellular de novo fatty acid synthesis in mammary gland which has been proved as the main source of short and medium-chain fatty acids of milk. However, the regulatory role of FASN in goat-specific milk fatty acids composition remains unclear. We cloned and analyzed the full-length of FASN gene from the mammary gland of Capra hircus (Xinong Saanen dairy goat) (DQ 915966). Comparative gene expression analysis suggested that FASN is predominantly expressed in fat, small intestine and mammary gland tissues, and expresses higher level at lactation period. Inhibition of FASN activity by different concentrations (0, 5, 15, 25 and 35 μM) of orlistat, a natural inhibitor of FASN, resulted in decreased expression of acetyl-CoA carboxylase α (ACCα), lipoprotein lipase and heart-type fatty acid binding protein (H-FABP) in a concentration-dependent manner in goat mammary gland epithelial cells (GMEC). Similar results were also obtained by silencing of FASN. Additionally, reduction of FASN expression also led to apparent decline of the relative content of decanoic acid (C10:0) and lauric acid (C12:0) in GMEC. Our study provides a direct evidence for inhibition of FASN reduces cellular medium-chain fatty acids synthesis in GMEC.