title: Fresh and nonfibrillar amyloid beta protein(1-40) induces rapid cellular degeneration in aged human fibroblasts: evidence for AbetaP-channel-mediated cellular toxicity.
abstract: Alzheimer's disease (AD) is primarily nonfamilial or sporadic (SAD) in origin, although several genetic linkages are reported. Tissues from AD patients contain fibrillar plaques made of 39 to 43 amino acid-long amyloid beta peptide (AbetaP), although the mechanisms of AbetaP toxicity are poorly understood. AbetaP(1-40) is the most prevalent AbetaP present in the neuronal and non-neuronal tissues from SAD patients. AbetaP(1-40) toxicity has been examined mainly after prolonged incubation and correlates with the age and fibrillar morphology of AbetaP(1-40). Globular and nonfibrillar AbetaPs are released continually during normal cellular metabolism; they elevate cellular Ca(2+) and form cation-permeable channels. However, their role in cellular toxicity is poorly understood. We have used an integrated atomic force and light fluorescence microscopy (AFM-LFM), laser confocal microscopy, and calcium imaging to examine real-time and acute effect of fresh and globular AbetaP(1-40) on cultured, aged human, AD-free fibroblasts. AFM images show that freshly prepared AbetaP(1-40) in phosphate-buffered saline (PBS) are globular and do not form fiber for an extended time period. AbetaP(1-40) induced rapid structural modifications, including cytoskeletal reorganization, retraction of cellular processes, and loss of cell-cell contacts, within minutes of incubation. This led to eventual cellular degeneration. AbetaP(1-40)-induced degeneration was prevented by anti-AbetaP antibody, zinc, and Tris, but not by tachykinin neuropeptides. In Ca(2+)-free extracellular medium, AbetaP(1-40) did not induce cellular degeneration. In the presence of extracellular Ca(2+), AbetaP(1-40) induced a sustained increase in the cellular Ca(2+). Thus, short-term and acute AbetaP(1-40) toxicity is mediated by Ca(2+) uptake, most likely via calcium-permeable AbetaP pores. Such rapid degeneration does not require fibrillar plaques, suggesting that the plaques may not have any causative role.
authors.affiliation: Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Zhu
authors.forename: H
authors.initials: H
authors.lastname: Lin
authors.forename: R
authors.initials: R
authors.lastname: Lal
mesh_terms: D000544:Alzheimer Disease / Q000209:etiology; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D000906:Antibodies / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D015220:Calcium Channels / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D048429:Cell Size / Q000187:drug effects; D016922:Cellular Senescence; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007365:Intercellular Junctions / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D011487:Protein Conformation; D013379:Substrate Specificity; D015320:Tachykinins / Q000494:pharmacology; D013997:Time Factors; D015032:Zinc / Q000494:pharmacology
chemical_list: D016229:Amyloid beta-Peptides; D000906:Antibodies; D015220:Calcium Channels; D010446:Peptide Fragments; D015320:Tachykinins; C078592:amyloid beta-protein (1-40); D015032:Zinc; D002118:Calcium