LDLR expression and localization are altered in mouse and human cell culture models of Alzheimer's disease

• Published in: PloS one 2010-01, Vol.5 (1), p.e8556-e8556
• Main Authors: Abisambra, Jose F, Fiorelli, Tina, Padmanabhan, Jaya, Neame, Peter, Wefes, Inge, Potter, Huntington
• Format: Article
• Language: English
• Subjects: Aberration; Adenoviruses; Advertising executives; Alzheimer Disease - genetics; Alzheimer Disease - metabolism; Alzheimer's disease; Animal models; Animals; Apolipoprotein E; Apolipoproteins; Atherosclerosis; Blotting, Western; Brain; Brain - metabolism; Cardiovascular Disorders/Vascular Biology; Cell Biology/Cytoskeleton; Cell Biology/Membranes and Sorting; Cell culture; Cells (Biology); Cells, Cultured; Cholesterol; Comparative analysis; Dementia; Dementia disorders; Disease Models, Animal; Disruption; Gene expression; Genetic engineering; Glycoproteins; Humans; Immunohistochemistry; Ligands; Lipid metabolism; Localization; Low density lipoprotein receptors; Low density lipoproteins; Medicine; Metabolism; Mice; mRNA; Mutation; Neurodegenerative diseases; Neurological Disorders/Alzheimer Disease; Neurons; Neuropathology; Overexpression; Pathogenesis; Phosphorylation; Physiological aspects; Polymerase chain reaction; Proteins; Receptor density; Receptors, LDL - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Risk factors; RNA; RNA, Messenger - genetics; Rodents; Sterols; Transgenic animals; Transgenic mice; Tubulin; Tubulin - metabolism; Western blotting
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0008556

Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the most common form of dementia. The major molecular risk factor for late-onset AD is expression of the epsilon-4 allele of apolipoprotein E (apoE), the major cholesterol transporter in the brain. The low-density lipoprotein receptor (LDLR) has the highest affinity for apoE and plays an important role in brain cholesterol metabolism. Using RT-PCR and western blotting techniques we found that over-expression of APP caused increases in both LDLR mRNA and protein levels in APP transfected H4 neuroglioma cells compared to H4 controls. Furthermore, immunohistochemical experiments showed aberrant localization of LDLR in H4-APP neuroglioma cells, Abeta-treated primary neurons, and in the PSAPP transgenic mouse model of AD. Finally, immunofluorescent staining of LDLR and of gamma- and alpha-tubulin showed a change in LDLR localization preferentially away from the plasma membrane that was paralleled by and likely the result of a disruption of the microtubule-organizing center and associated microtubule network. These data suggest that increased APP expression and Abeta exposure alters microtubule function, leading to reduced transport of LDLR to the plasma membrane. Consequent deleterious effects on apoE uptake and function will have implications for AD pathogenesis and/or progression.