This protocol describes the synthesis, characterization, and injection of monomeric amyloid-β42 peptides for generating amyloid toxicity in adult zebrafish to establish an Alzheimer's disease model, followed by histological analyses and detection of aggregations.
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Method Article
Modeling Amyloid-β42 Toxicity and Neurodegeneration in Adult Zebrafish Brain
In This Article
Summary
Abstract
Alzheimer's disease (AD) is a debilitating neurodegenerative disease in which accumulation of toxic amyloid-β42 (Aβ42) peptides leads to synaptic degeneration, inflammation, neuronal death, and learning deficits. Humans cannot regenerate lost neurons in the case of AD in part due to impaired proliferative capacity of the neural stem/progenitor cells (NSPCs) and reduced neurogenesis. Therefore, efficient regenerative therapies should also enhance the proliferation and neurogenic capacity of NSPCs. Zebrafish (Danio rerio) is a regenerative organism, and we can learn the basic molecular programs with which we could design therapeutic approaches to tackle AD. For this reason, the generation of an AD-like model in zebrafish was necessary. Using our methodology, we can introduce synthetic derivatives of Aβ42 peptide with tissue penetrating capability into the adult zebrafish brain, and analyze the disease pathology and the regenerative response. The advantage over the existing methods or animal models is that zebrafish can teach us how a vertebrate brain can naturally regenerate, and thus help us to treat human neurodegenerative diseases better by targeting endogenous NSPCs. Therefore, the amyloid-toxicity model established in the adult zebrafish brain may open new avenues for research in the field of neuroscience and clinical medicine. Additionally, the simple execution of this method allows for cost-effective and efficient experimental assessment. This manuscript describes the synthesis and injection of Aβ42 peptides into zebrafish brain.
Introduction
AD is a chronic progressive disease characterized by the loss of neurons and synapses in the cerebral cortex1,2,3,4,5. The classical neuropathological hallmarks of AD are the deposition of amyloid peptides and formation of the neurofibrillary tangles (NFTs)6. Senile plaques, also known as amyloid plaques, are composed of amyloid-β (Aβ) peptides that form β-pleated structures in the brain parenchyma5. The accumulation of Aβ42 in AD patients ....
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Protocol
This protocol is a standard procedure suggested by the EU guidelines (2010/63) and the European Society for Fish Models in Biology and Medicine (EuFishBioMed) in Karlsruhe Insitute of Technology (KIT). All methods described after here have been approved by the ethics commission (Landesdirektion Dresden; document number TVV-52/2015).
1. Preparation of Aβ42 Peptide
- Synthesize peptides (see Table 1) using the standard 9-fluorenylmethoxycarbonyl (Fmoc) chemistry with 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronoiumhexafluorphosphate (HBTU) as the coupling reagent on an automated solid-phase peptide synthesi....
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Results
HPLC was used to purify the synthesized peptide and mass spectrometry has been used to characterize the purified amyloid β peptides. The HPLC column was heated to 50 °C to improve the separation of the Aβ peptides and all the fractions were collected. To identify the correctly synthesized peptide, mass spectroscopy analysis was performed for all fractions. The UPLC chromatogram shows the purity of the compound. The HPLC fraction that yielded one peak on the UPLC (i.e., the correc.......
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Discussion
The amyloid peptides can be modified to include sequence variations or various tags. For instance, a scrambled amyloid peptide can be generated, and the peptides can be labeled with fluorescent tags at the N-terminus of the peptide end or tagged with carrier peptides39. Similarly, in this protocol, the carrier peptide is the cell-penetrating peptide TR because of its effectiveness to transport cargo deep into the brain tissue39. Additionally, our method allows for injection.......
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Disclosures
The authors have nothing to disclose
Acknowledgements
This work was supported by DZNE and the Helmholtz Association (VH-NG-1021), CRTD, TU Dresden (FZ-111, 043_261518), and DFG (KI1524/6) (C.K.); and by the Leibniz Association (SAW-2011-IPF-2) and BMBF (BioLithoMorphie 03Z2E512) (Y.Z.). We would also like to thank Ulrike Hofmann for peptide synthesis, and to Nandini Asokan, Prayag Murawala, and Elly Tanaka for help during filming the procedure.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Fmoc-protected amino acids | IRIS Biotech GmbH (Marktredwitz, Germany) | Fmoc-based amino acids for solid phase peptide synthesis (SPPS) | |
| N,N,N′,N′-Tetramethyl-O-(1H-benzotriazol-1-yl)uronium hexafluorophosphate (HBTU) | IRIS Biotech GmbH (Marktredwitz, Germany) | RL-1030 | Activator |
| Oxyma | IRIS Biotech GmbH (Marktredwitz, Germany) | RL-1180 | Racemization supressor |
| N,N-Diisopropylethylamine | IRIS Biotech GmbH (Marktredwitz, Germany) | SOL-003 | Base |
| Dimethylformamide | IRIS Biotech GmbH (Marktredwitz, Germany) | SOL-004 | Solvent |
| N-Methylmorpholine | Thermo Fisher (Kandel) GmbH, Germany | A12158 | Base |
| 1-Hydroxybenzotriazole hydrate (HOBT) | Sigma-Aldrich Co. LLC. (St. Louis, MO, USA) | 157260 ALDRICH | Activator |
| Piperidine | MERCK KGaA (Darmstadt, Germany) | 822299 | Fmoc deprotection reagent |
| Dichlormethane (DCM) | MERCK KGaA (Darmstadt, Germany) | 106050 | Solvent |
| Formic acid (FA) | MERCK KGaA (Darmstadt, Germany) | 100264 | Buffer component for HPLC |
| Trifluoroacetic acid (TFA) | MERCK KGaA (Darmstadt, Germany) | 808260 | Clevage Mixture reagent |
| Triisopropylsilane(TIS) | MERCK KGaA (Darmstadt, Germany) | 233781 ALDRICH | Clevage Mixture reagent |
| Acetonitrile (for UPLC/LCMS) | Sigma-Aldrich Laborchemikalien GmbH | 34967-1L | Solvent |
| Acetonitrile (for HPLC) | VWR International Ltd, England | 83639.320 | Solvent |
| Diethylether | VWR International Ltd, England | 23811.326 | Solvent for peptide precipitation |
| Dithiotritol (DTT) | VWR International Ltd, England | 0281-25G | Clevage Mixture reagent |
| TentaGel S RAM Fmoc rink amide resin | Rapp Polymere GmbH (Tuebingen, Germany) | S30023 | Solid phase for SPPS |
| Peptide synthesis 5 ml syringes with included filters | Intavis AG (Cologne, Germany) | 34.274 | Reaction tube for SPPS and for clevage from the Solid Phase |
| Polytetrafluoroethylene (PTFE) filter | Sartorius Stedtim (Aubagne, France) | 11806-50-N | Filteration of precipitated peptides |
| Polyvinylidenefluoride (PVDF) syringe filter | Carl Roth GmbH + Co. KG Karlsruhe | KC78.1 | Pre-filteration for HPLC |
| Peptide Synthesizer | Intavis, Cologne, Germany | ResPep SL | Automated solid-phase peptide synthesizer |
| Water Alliance HPLC | Waters, Milford Massachusetts, USA | Waters 2998, Waters e2695 | Semi-preparative reverse-phase high pressure liquid chromatography (HPLC) |
| PolymerX, bead size 10μm, 250x10 mm | Phenomenex Ltd. Germany | 00G-4328-N0 | Porous polystyrene divinylbenzene HPLC column |
| Milli-Q Advantage A10, with a Milli-Q filter | EMD Millipore Corporation, Billerica, MA, USA | LCPAK0001 | Water purification system |
| Filtration Unit | Sartorius Stedtim (Aubagne, France) | 16307 | Filtration unit for peptide precipitation |
| UPLC Aquity with UV Detector | Waters, Milford Massachusetts, USA | M09UPA 664M | Analytical reverse phase ultra HPLC for LC-MS |
| ACQUITY UPLC BEH C18, bead size 1.7 μm, 50x2.1 mm | Waters, Milford Massachusetts, USA | 186002350 | Analytical C18 column |
| ACQUITY TQ Detector | Waters, Milford Massachusetts, USA | QBB908 | Electrospray ionization mass spectrometry (ESI-MS) |
| CHRIST ALPHA 2-4 LD plus + vacuubrand RZ6 | Martin Christ Gefriertrocknungsanlagen GmbH, Germany | 16706, 101542 | Lyophilizer with vaccum pump |
| Paradigm plate reader | Beckman Coulter | ||
| MESAB (ethyl-m-aminobenzoate methanesulphonate) | Sigma-Aldrich | A5040 | |
| Petri dishes | Sarstedt | 821.472 | |
| Phosphate-buffered saline | Life Technologies, GIBCO | 10010-056 | |
| Needle | Becton-Dickinson | 305178 | |
| Dissecting microscope | Olympus, Leica, Zeiss | Varies with the manufacturer | |
| Dumont Tweezers | World Precision Instruments | 501985 | |
| Gillies Dissecting Forceps | World Precision Instruments | 501265 | |
| Glass injection capillaries | World Precision Instruments | TWF10 | |
| PicoNozzle | World Precision Instruments | 5430-12 | |
| Pneumatic PicoPump | World Precision Instruments | SYS-PV820 | |
| Ring illuminator; Ring Light Guide | Parkland Scientific | ILL-RLG | |
| Cryostat | Leica | CM1950 |
References
- LaFerla, F. M., Green, K. N. Animal models of Alzheimer disease. Cold Spring Harb Perspect Med. 2 (11), (2012).
- Selkoe, D. J. Alzheimer's disease: genes, proteins, and therapy. Physiol Rev. 81 (2), 741-766 (2001).
- Serpell, L. C.
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