title: Palmitic acid-treated astrocytes induce BACE1 upregulation and accumulation of C-terminal fragment of APP in primary cortical neurons.
abstract: High-fat diet is a significant risk factor for the development of Alzheimer's disease (AD). In addition, the AD brain is characterized by elevated levels of fatty acids as compared to that of healthy controls. Despite this, it is unclear how elevated levels of fatty acids are related to the pathogenesis of AD. The present study examines the role of saturated fatty acid, palmitic acid (PA), in causing BACE1 upregulation and consequent amyloidogenic processing of beta-amyloid precursor protein (APP), one of the main characteristic signatures of AD pathology. Here, primary rat cortical neurons and astrocytes were treated with pathological concentration of PA. There was no change in the BACE1 levels in the rat cortical neurons treated directly with PA as compared to controls. The conditioned medium from PA-treated astrocytes, however, caused BACE1 upregulation in the cortical neurons. Moreover, there was a consequent increase in the cleavage of APP leading to the accumulation of the C-terminal fragment of APP (C99) in the cortical neurons. Co-treatment of neurons with 1,3-dimethyl urea (DMU), an antioxidant, decreased PA-induced upregulation in the levels of BACE1 and C99. The present results establish an important role of saturated fatty acids in AD-associated amyloidogenesis through astroglia-mediated oxidative stress.
authors.affiliation: Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, MI-48823, USA.
authors.forename: Sachin
authors.initials: S
authors.lastname: Patil
authors.forename: Lufang
authors.initials: L
authors.lastname: Sheng
authors.forename: Alexis
authors.initials: A
authors.lastname: Masserang
authors.forename: Christina
authors.initials: C
authors.lastname: Chan
mesh_terms: D000544:Alzheimer Disease / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000096:biosynthesis*; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D010450:Endopeptidases / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D019308:Palmitic Acid / Q000494:pharmacology*; D010446:Peptide Fragments / Q000378:metabolism; D058225:Plaque, Amyloid / Q000187:drug effects / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D000975:Antioxidants; D017077:Culture Media, Conditioned; D010446:Peptide Fragments; D019308:Palmitic Acid; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases