Defining α-synuclein species responsible for Parkinson disease phenotypes in mice
alpha-synuclein (a-synuclein); amyloid; cytotoxicity; fibril; Lewy Body; motor behavior defect; neurodegenerative disease; oligomer; Parkinson disease; protein aggregation
Parkinson disease (PD) is a neurodegenerative disorder characterized by fibrillar neuronal inclusions composed of aggregated α-synuclein. These inclusions are associated with behavioral and pathological PD phenotypes. One strategy for therapeutic interventions is to prevent the formation of these inclusions in order to halt disease progression. α-Synuclein exists in multiple structural forms, including disordered, non-amyloid oligomers, ordered amyloid oligomers, and fibrils. It is critical to understand which conformers contribute to specific PD phenotypes. Here, we utilized a mouse model to explore the pathological effects of stable amyloid β-sheet oligomers compared with those of fibrillar α-synuclein. We biophysically characterized these species with transmission EM, atomic-force microscopy, CD spectroscopy, FTIR spectroscopy, analytical ultracentrifugation, and thioflavin T assays. We then injected these different α-synuclein forms into the mouse striatum to determine their ability to induce PD-related phenotypes. We found that β-sheet oligomers produce a small but significant loss of dopamine neurons in the substantia nigra pars compacta (SNc). Injection of small β-sheet fibril fragments, however, produced the most robust phenotypes, including reduction of striatal dopamine terminals, SNc loss of dopamine neurons, and motor behavior defects. We conclude that although the β-sheet oligomers cause some toxicity, the potent effects of the short fibrillar fragments can be attributed to their ability to recruit monomeric α-synuclein and spread in vivo and hence contribute to the development of PD-like phenotypes. These results suggest that strategies to reduce the formation and propagation of β-sheet fibrillar species could be an important route for therapeutic intervention in PD and related disorders.
Froula Jessica M; Castellana-Cruz Marta; Anabtawi Nadia M; Camino José D; Chen Serene W; Thrasher Drake R; Freire Jennifer; Yazdi Allen A; Fleming Sheila; Dobson Christopher M; Kumita Janet R; Cremades Nunilo; Volpicelli-Daley Laura A
The Journal of Biological Chemistry
2019
2019-05
<a href="http://doi.org/10.1074/jbc.RA119.007743" target="_blank" rel="noreferrer noopener">10.1074/jbc.RA119.007743</a>
Knockdown of amyloid precursor protein normalizes cholinergic function in a cell line derived from the cerebral cortex of a trisomy 16 mouse: An animal model of Down syndrome
16 mice; abnormalities; acetylcholine; acetylcholine-release; alzheimers-disease; amyloid; antisense; beta-protein; calcium; cell line; Down syndrome; Neurosciences & Neurology; neurotoxicity; peptide; rat hippocampal slices; root ganglion neurons
We have generated immortal neuronal cell lines from normal and trisomy 16 (Ts16) mice, a model for Down syndrome (DS). Ts16 lines overexpress DS-related genes (App, amyloid precursor protein; Sod1, Cu/Zn superoxide dismutase) and show altered cholinergic function (reduced choline uptake, ChAT expression and fractional choline release after stimulation). As previous evidence has related amyloid to cholinergic dysfunction, we reduced APP expression using specific mRNA antisense sequences in our neuronal cell line named CTb, derived from Ts16 cerebral cortex, compared to a cell line derived from a normal animal, named CNh. After transfection, Western blot studies showed APP expression knockdown in CTb cells of 36% (24 hr), 40.4% (48 hr), and 50.2% (72 hr) compared to CNh. Under these reduced APP levels, we studied 3 H-choline uptake in CTb and CNh cells. CTb, as reported previously, expressed reduced choline uptake compared to CNh cells (75%, 90%, and 69% reduction at 1, 2, and 5 min incubation, respectively). At 72 hr of APP knockdown, choline uptake levels were essentially similar in both cell types. Further, fractional release of H-3-choline in response to glutamate, nicotine, and depolarization with KCI showed a progressive increase after APP knockdown, reaching values similar to those of CNh after 72 hr of transfection. The results suggest that APP overexpression in CTb cells contributes to impaired cholinergic function, and that gene knockdown in CTb cells is a relevant tool to study DS-related dysfunction. (c) 2006 Wiley-Liss, Inc.
Opazo P; Saud K; de Saint Pierre M; Cardenas A M; Allen D D; Segura-Aguilar J; Caviedes R; Caviedes P
Journal of Neuroscience Research
2006
2006-11
Journal Article
<a href="http://doi.org/10.1002/jnr.21035" target="_blank" rel="noreferrer noopener">10.1002/jnr.21035</a>