Expression of E-FABP in PC12 cells increases neurite extension during differentiation: involvement of n-3 and n-6 fatty acids.
Epidermal fatty acid-binding protein (E-FABP), a member of the family of FABPs, exhibits a robust expression in neurons during axonal growth in development and in nerve regeneration following nerve injury. This study examines the impact of E-FABP expression in normal neurite extension in differentiating pheochromocytoma cell (PC12) cultures supplemented with selected long chain free fatty acids (LCFFA). We found that E-FABP binds to a broad range of saturated and unsaturated LCFFAs, including those with potential interest for neuronal differentiation and axonal growth such as C22:6n-3 docosahexaenoic acid (DHA), C20:5n-3 eicosapentaenoic acid (EPA), and C20:4n-6 arachidonic acid (ARA). PC12 cells exposed to nerve growth factor (NGFDPC12) exhibit high E-FABP expression that is blocked by mitogen-activated protein kinase kinase (MEK) inhibitor U0126. Nerve growth factor-differentiated pheochromocytoma cells (NGFDPC12) antisense clones (NGFDPC12-AS) which exhibit low E-FABP expression have fewer/shorter neurites than cells transfected with vector only or NGFDPC12 sense cells (NGFDPC12-S). Replenishing NGFDPC12-AS cells with biotinylated recombinant E-FABP (biotin-E-FABP) protein restores normal neurite outgrowth. Cellular localization of biotin-E-FABP in NGFDPC12 was detected mostly in the cytoplasm and in the nuclear region. Treatment of NGFDPC12 with DHA, EPA, or ARA further enhances neurite length but it does not trigger further induction of TrkA or MEK phosphorylation or E-FABP mRNA observed in differentiating PC12 cells without LCFFA supplementation. Significantly, DHA and EPA neurite stimulating effects are higher in NGFDPC12-S than in NGFDPC12-AS cells. These findings are consistent with the scenario that neurite extension of differentiating PC12 cells, including further stimulation by DHA and EPA, requires sufficient cellular levels of E-FABP.
Liu
Jo-Wen
JW
Center for Health Disparities and Molecular Medicine, Department of Basic Science, Loma Linda University, California 92350, USA.
Almaguel
Frankis G
FG
Bu
Liming
L
De Leon
Daisy D
DD
De Leon
Marino
M
D000818:Animals; D002451:Cell Compartmentation / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D004281:Docosahexaenoic Acids / Q000378:metabolism / Q000494:pharmacology; D015118:Eicosapentaenoic Acid / Q000378:metabolism / Q000494:pharmacology; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D050556:Fatty Acid-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015525:Fatty Acids, Omega-3 / Q000378:metabolism* / Q000494:pharmacology; D043371:Fatty Acids, Omega-6 / Q000378:metabolism* / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects / Q000502:physiology*; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020932:Nerve Growth Factor / Q000378:metabolism / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D016716:PC12 Cells; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000494:pharmacology
D005136:Eye Proteins; C107356:Fabp5 protein, rat; D050556:Fatty Acid-Binding Proteins; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D009419:Nerve Tissue Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D011993:Recombinant Fusion Proteins; D004281:Docosahexaenoic Acids; D020932:Nerve Growth Factor; D015118:Eicosapentaenoic Acid; D048369:MAP Kinase Kinase 1