Utility of an improved model of amyloid-beta (A beta(1-42)) toxicity in Caenorhabditis elegans for drug screening for Alzheimer's disease

The electronic version of this article is the complete one and can be found online at: http://www.molecularneurodegeneration.com/content/7/1/57 Extent: 9p.Background: The definitive indicator of Alzheimer’s disease (AD) pathology is the profuse accumulation of amyloid-ß (Aß) within the brain. Various in vitro and cell-based models have been proposed for high throughput drug screening for potential therapeutic benefit in diseases of protein misfolding. Caenorhabditis elegans offers a convenient in vivo system for examination of Aß accumulation and toxicity in a complex multicellular organism. Ease of culturing and a short life cycle make this animal model well suited to rapid screening of candidate compounds. Results: We have generated a new transgenic strain of C. elegans that expresses full length Aß1-42. This strain differs from existing Aß models that predominantly express amino-truncated Aß3-42. The Aß1-42 is expressed in body wall muscle cells, where it oligomerizes, aggregates and results in severe, and fully penetrant, age progressive-paralysis. The in vivo accumulation of Aß1-42 also stains positive for amyloid dyes, consistent with in vivo fibril formation. The utility of this model for identification of potential protective compounds was examined using the investigational Alzheimer’s therapeutic PBT2, shown to be neuroprotective in mouse models of AD and significantly improve cognition in AD patients. We observed that treatment with PBT2 provided rapid and significant protection against the Aß-induced toxicity in C. elegans. Conclusion: This C. elegans model of full length Aß1-42 expression can now be adopted for use in screens to rapidly identify and assist in development of potential therapeutics and to study underlying toxic mechanism(s) of Aß.Gawain McColl, Blaine R Roberts, Tara L Pukala, Vijaya B Kenche, Christine M Roberts, Christopher D Link, Timothy M Ryan, Colin L Masters, Kevin J Barnham, Ashley I Bush, and Robert A Chern

Platinum-based inhibitors of amyloid-beta as therapeutic agents for Alzheimer's disease

Amelyoid-beta peptide (Abeta) is a major causative agent responsible for Alzheimer's disease (AD). Abeta contains a high affinity metal binding site that modulates peptide aggregation and toxicity. Therefore, identifying molecules targeting this site represents a valid therapeutic strategy. To test this hypothesis, a range of L-PtCl(2) (L = 1,10-phenanthroline derivatives) complexes were examined and shown to bind to Abeta, inhibit neurotoxicity and rescue Abeta-induced synaptotoxicity in mouse hippocampal slices. Coordination of the complexes to Abeta altered the chemical properties of the peptide inhibiting amyloid formation and the generation of reactive oxygen species. In comparison, the classic anticancer drug cisplatin did not affect any of the biochemical and cellular effects of Abeta. This implies that the planar aromatic 1,10-phenanthroline ligands L confer some specificity for Abeta onto the platinum complexes. The potent effect of the L-PtCl(2) complexes identifies this class of compounds as therapeutic agents for AD

Acetylcholine-like and Trimethylglycine-like PTA (1,3,5-Triaza-7-phosphaadamantane) Derivatives for the Development of Innovative Ru- and Pt-Based Therapeutic Agents

The PTA N-alkyl derivatives (PTAC2H4OCOMe)X (1X:1a, X = Br; 1b,X=I; 1c, X=PF6; 1d, X = BPh4), (PTACH2COOEt)X (2X: 2a, X = Br; 2b, X = Cl; 2c,X=PF6), and (PTACH2CH2COOEt)X (3X: 3a, X = Br; 3c, X=PF6), presenting all the functional groups of the natural cationic compounds acetylcholine or trimethylglycine combined with a P-donor site suitable for metal ion coordination, were prepared and characterized by NMR, ESI-MS, and elemental analysis. The X-ray crystal structures of 1d and 2c were determined. Ligands 1c, 2b, and 3c were coordinated to Pt(II) and Ru(II) to give the cationic complexes cis-[PtCl2(L)2]X2 and [RuCpCl(PPh3)(L)]X (L=1, 2, 3,X=Cl or PF6) designed with a structure targeted for anticancer activity. The X-ray crystal structure of [CpRu(PPh3)PTAC2H4OCOMe)Cl]PF6 (1c Ru) was deter-mined. The antiproliferative activity of the ligands and the complexes was evaluated on three human cancer cell lines