title: Macromolecular and small-molecule modulation of intracellular Aβ42 aggregation and associated toxicity.
abstract: Aβ (amyloid β-peptide) has a central role in AD (Alzheimer's disease) where neuronal toxicity is linked to its extracellular and intracellular accumulation as oligomeric species. Searching for molecules that attenuate Aβ aggregation could uncover novel therapies for AD, but most studies in mammalian cells have inferred aggregation indirectly by assessing levels of secreted Aβ peptide. In the present study we establish a mammalian cell system for the direct visualization of Aβ formation by expression of an Aβ(42)-EGFP (enhanced green fluorescent protein) fusion protein in the human embryonic kidney cell line T-REx293, and use this to identify both macromolecules and small molecules that reduce aggregation and associated cell toxicity. Thus a molecular shield protein AavLEA1 [Aphelenchus avenae LEA (late embryogenesis abundant) protein 1], which limits aggregation of proteins with expanded poly(Q) repeats, is also effective against Aβ(42)-EGFP when co-expressed in T-REx293 cells. A screen of polysaccharide and small organic molecules from medicinal plants and fungi reveals one candidate in each category, PS5 (polysaccharide 5) and ganoderic acid DM respectively, with activity against Aβ. Both PS5 and ganoderic acid DM probably promote Aβ aggregate clearance indirectly through the proteasome. The model is therefore of value to study the effects of intracellular Aβ on cell physiology and to identify reagents that counteract those effects.
authors.affiliation: Cell and Organism Engineering Laboratory, Department of Chemical Engineering and Biotechnology, University of Cambridge, UK.
authors.forename: Sohini
authors.initials: S
authors.lastname: Chakrabortee
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.forename: Liao
authors.initials: L
authors.lastname: Zhang
authors.forename: Helena R
authors.initials: HR
authors.lastname: Matthews
authors.forename: Hanrui
authors.initials: H
authors.lastname: Zhang
authors.forename: Ni
authors.initials: N
authors.lastname: Pan
authors.forename: Chun-ru
authors.initials: CR
authors.lastname: Cheng
authors.forename: Shu-hong
authors.initials: SH
authors.lastname: Guan
authors.forename: De-an
authors.initials: DA
authors.lastname: Guo
authors.forename: Zebo
authors.initials: Z
authors.lastname: Huang
authors.forename: Yizhi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Alan
authors.initials: A
authors.lastname: Tunnacliffe
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D002478:Cells, Cultured; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D014162:Transfection
chemical_list: D016229:Amyloid beta-Peptides; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins