Anchored FRET sensors detect local caspase activation prior to neuronal degeneration

• Published in: Molecular neurodegeneration 2011-05, Vol.6 (1), p.35-35, Article 35
• Main Authors: Figueroa, Ricardo A, Ramberg, Veronica, Gatsinzi, Tom, Samuelsson, Malin, Zhang, Mu, Iverfeldt, Kerstin, Hallberg, Einar
• Format: Article
• Language: English
• Subjects: Alzheimer's disease; Amyloid-beta; Amyloid-β; Biochemistry; biokemi; Caspases; Cell death; Energy transformation; FRET; Genetic aspects; Live Cell Imaging; Neurite degeneration; Neurochemistry and Neurotoxicology; Neurochemistry with Molecular Neurobiology; Neurodegeneration; neurokemi med molekylär neurobiologi; neurokemi och neurotoxikologi; Neurons; Peptides; Physiological aspects; Risk factors; Spatiotemporal analysis
• ISSN: 1750-1326; 1750-1326
• DOI: 10.1186/1750-1326-6-35

Recent studies indicate local caspase activation in dendrites or axons during development and in neurodegenerative disorders such as Alzheimer's disease (AD). Emerging evidences point to soluble oligomeric amyloid-β peptide as a causative agent in AD. Here we describe the design of fluorescence resonance energy transfer (FRET)-based caspase sensors, fused to the microtubule associated protein tau. Specific caspase sensors preferentially cleaved by caspase-3, -6 or -9 were expressed in differentiated human neuroblastoma SH-SY5Y cells. The anchoring of the sensors resulted in high FRET signals both in extended neurites and soma and made analysis of spatiotemporal signal propagation possible. Caspase activation was detected as loss of FRET after exposure to different stimuli. Interestingly, after staurosporine treatment caspase-6 activation was significantly delayed in neurites compared to cell bodies. In addition, we show that exposure to oligomer-enriched amyloid-β peptide resulted in loss of FRET in cells expressing sensors for caspase-3 and -6, but not -9, in both soma and neurites before neurite degeneration was observed. Taken together, the results show that by using anchored FRET sensors it is possible to detect stimuli-dependent differential activation of caspases and to distinguish local from global caspase activation in live neuronal cells. Furthermore, in these cells oligomer-enriched amyloid-β peptide induces a global, rather than local activation of caspase-3 and -6, which subsequently leads to neuronal cell death.