Neonatal AAV delivery of alpha-synuclein induces pathology in the adult mouse brain

Abstract

Abnormal accumulation of alpha-synuclein (αsyn) is a pathological hallmark of Lewy body related disorders such as Parkinson’s disease and Dementia with Lewy body disease. During the past two decades, a myriad of animal models have been developed to mimic pathological features of synucleinopathies by over-expressing human αsyn. Although different strategies have been used, most models have little or no reliable and predictive phenotype. Novel animal models are a valuable tool for understanding neuronal pathology and to facilitate development of new therapeutics for these diseases. Here, we report the development and characterization of a novel model in which mice rapidly express wild-type αsyn via somatic brain transgenesis mediated by adeno-associated virus (AAV). At 1, 3, and 6 months of age following intracerebroventricular (ICV) injection, mice were subjected to a battery of behavioral tests followed by pathological analyses of the brains. Remarkably, significant levels of αsyn expression are detected throughout the brain as early as 1 month old, including olfactory bulb, hippocampus, thalamic regions and midbrain. Immunostaining with a phospho-αsyn (pS129) specific antibody reveals abundant pS129 expression in specific regions. Also, pathologic αsyn is detected using the disease specific antibody 5G4. However, this model did not recapitulate behavioral phenotypes characteristic of rodent models of synucleinopathies. In fact no deficits in motor function or cognition were observed at 3 or 6 months of age. Taken together, these findings show that transduction of neonatal mouse with AAV-αsyn can successfully lead to rapid, whole brain transduction of wild-type human αsyn, but increased levels of wildtype αsyn do not induce behavior changes at an early time point (6 months), despite pathological changes in several neurons populations as early as 1 month.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-017-0455-3) contains supplementary material, which is available to authorized users.

Investigating the neuroprotective effect of AAV-mediated β-synuclein overexpression in a transgenic model of synucleinopathy

“…However, even though we could not detect any protective effects of β-syn, our study confirms that an AAV vector is suitable for long-term overexpression of proteins into the CNS. Notably, after ICV inoculations of AAV in neonates, we confirmed a widespread expression of the protein, as this was also recently described using an α-syn AAV vector 33 . The injection of AAV in the VTA also allowed to express human β-syn in various connected regions, as suggested in a previous study using serotype 9 AAV vector carrying a lysosomal enzyme gene 13 .…”

Soluble endogenous oligomeric α-synuclein species in neurodegenerative diseases: Expression, spreading, and cross-talk

“…Lastly, two very recent studies from the Holtzman and Bu groups investigated whether APOE 4 genotype, a major risk factor for neurodegenerative diseases, affected ␣Syn pathology in mice and subjects with PD [144,145]. While both studies relied on APOE knock-in (E2/E3/E4) backgrounds to compare the impact of APOE 2/3/4 alleles in mouse models of synucleinopathy, Davis and colleagues used G2.3 TgA53T mice [145]; Zhao and coworkers opted for an AAV-mediated overexpression of human ␣Syn WT , which does not cause amyloid inclusions as defined by a lack of Thioflavin-S positivity [144,146]. In both experimental settings, E4 exacerbated ␣Syn pathology, including pathological conformational changes detected by the antibody 5G4 and pS129-␣Syn accumulation, and worsened motor deficits.…”

In VivoDetection of Extracellular Adenosine Triphosphate in a Mouse Model of Traumatic Brain Injury

“…AAV injections as previously described. 44 Briefly, newborn (P0) albino mice were cryoanesthetized and injected bilaterally with AAV2/9 using a 32-gauge Hamilton needle inserted 1 mm to the right of the midline point equidistant from each eye and 1 mm posterior to a line drawn from the anterior base of the eye. Neonatal mice were returned to parents until weaned.…”