L-FABP and I-FABP expression increase NBD-stearate uptake and cytoplasmic diffusion in L cells.
The effects of intestinal and liver fatty acid binding protein (I- and L-FABP, respectively) expression on single-cell fatty acid uptake, internalization, and cytoplasmic diffusion were determined in transfected L cell fibroblasts. These parameters were measured using the nonesterifiable fluorescent fatty acid probe 12-N-methyl-(7-nitrobenz-2-oxa-1,3-diazol)aminostearate (NBD-stearate) and fluorescence digital imaging. In single-cell fluorescence imaging experiments, L-FABP-expressing cells, but not I-FABP-expressing cells, increased NBD-stearate uptake 1.7-fold compared with control cells. Both I- and L-FABP increased the cytoplasmic diffusion rate of the internalized NBD-stearate 2.6- and 1.9-fold, respectively, compared with control cells. However, increased NBD-stearate lateral membrane mobility was observed only in L-FABP-expressing cells. After incubation of the cells with 4 microM NBD-stearate at 37 degrees C for 30 min, fluorescence deconvolution imaging indicated that NBD-stearate was localized primarily into lipid droplets in all cell lines. The differential effect of these proteins on fatty acid uptake and intracellular trafficking in single cells illustrates a possible difference in the physiological function of I- and L-FABP in intact cells.
Department of Physiology and Pharmacology, Texas A & M University, College Station, Texas 77843-4466, USA.
E J
EJ
Murphy
D009327:4-Chloro-7-nitrobenzofurazan / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004058:Diffusion; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism; D005456:Fluorescent Dyes; D007413:Intestinal Mucosa / Q000378:metabolism; D007700:Kinetics; D007739:L Cells; D008099:Liver / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D018996:Myelin P2 Protein / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D013228:Stearates / Q000493:pharmacokinetics*; D014162:Transfection
D002352:Carrier Proteins; C493320:Fabp1 protein, mouse; C082667:Fabp5 protein, mouse; C086936:Fabp7 protein, mouse; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D005456:Fluorescent Dyes; D018996:Myelin P2 Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D013228:Stearates; C060027:12-N-methyl-7-nitrobenzo-2-oxa-1,3-diazolamino stearate; D009327:4-Chloro-7-nitrobenzofurazan