Tracing brain genotoxic stress in Parkinson’s disease with a novel single-cell genetic sensor

Abstract

To develop an in vivo tool to probe brain genotoxic stress, we designed a viral proxy as a single-cell genetic sensor termed PRISM that harnesses the instability of recombinant adeno-associated virus genome processing and a hypermutable repeat sequence–dependent reporter. PRISM exploits the virus-host interaction to probe persistent neuronal DNA damage and overactive DNA damage response. A Parkinson’s disease (PD)–associated environmental toxicant, paraquat (PQ), inflicted neuronal genotoxic stress sensitively detected by PRISM. The most affected cell type in PD, dopaminergic (DA) neurons in substantia nigra, was distinguished by a high level of genotoxic stress following PQ exposure. Human alpha-synuclein proteotoxicity and propagation also triggered genotoxic stress in nigral DA neurons in a transgenic mouse model. Genotoxic stress is a prominent feature in PD patient brains. Our results reveal that PD-associated etiological factors precipitated brain genotoxic stress and detail a useful tool for probing the pathogenic significance in aging and neurodegenerative disorders.

Somatic SNCA Copy Number Variants in Multiple System Atrophy are Related to Pathology and Inclusions

“…We have not, however, demonstrated increased mRNA, which cannot presently be measured together with DNA FISH. Furthermore, we cannot exclude the possibility that α-synuclein aggregation causes DNA damage 25 leading to somatic mutations such as SNCA CNVs, although even in this case a CNV may further potentiate aggregation. 12 Inclusion development in an oligodendrocyte with a CNV may be facilitated by TPPP expression, which leads to the highly toxic MSA α-synuclein strain.…”

DNA Damage-Mediated Neurotoxicity in Parkinson’s Disease

“…Moreover, there were also much higher levels of 8-OHdG in the plasma, urine, and cerebrospinal fluid of PD patients than in controls [ 27 ]. In addition to oxidative damage, numerous studies have also found a significant upregulation of γ-H2AX, a hallmark of DNA double-strand breaks (DSBs) [ 18 , 28 ], in PD. Notably, this type of damage not only covers DA neurons, but also microglia [ 28 ].…”

“…In addition to oxidative damage, numerous studies have also found a significant upregulation of γ-H2AX, a hallmark of DNA double-strand breaks (DSBs) [ 18 , 28 ], in PD. Notably, this type of damage not only covers DA neurons, but also microglia [ 28 ]. To date, DNA damage-mediated neurotoxicity has been demonstrated in various toxin models of PD [ 15 ].…”

“…To date, DNA damage-mediated neurotoxicity has been demonstrated in various toxin models of PD [ 15 ]. For example, both 8-OHdG and γ-H2AX can be induced by PD-associated neurotoxins, including 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, paraquat, and 6-hydroxydopamine (6-OHDA) [ 28 , 29 , 30 , 31 , 32 , 33 ]. What is more, DNA damage-dependent activation of downstream signaling contributed to the degeneration and death of DA neurons in PD mouse models [ 34 , 35 , 36 , 37 , 38 ], suggesting that DNA damage may be an important link in the pathogenesis of sporadic PD.…”

“…Whether in vivo or in vitro models, rotenone has been reported to cause both oxidative DNA damage and DSBs [ 83 , 84 ]. Moreover, exposure to paraquat can also elicit genotoxic stress in post-mitotic DA neurons [ 28 ]. These findings provide the proof of concept that DNA damage is a shared pathway in the degenerative death of DA neurons caused by environmental toxins.…”