Polymerase I (Pol I) is at the epicenter of ribosomal RNA (rRNA) synthesis. Pol I is a target for treatment of cancer. Given the many cellular commonalities between cancer and neurodegeneration (i.e., different faces of the same coin) it seems rational to consider targeting of Pol I or, more generally, rRNA synthesis for treatment of disorders associated with the death of terminally differentiated neurons. Principally, ribosomes synthesize proteins and, accordingly, Pol I can be considered the starting point for protein synthesis. Given that cellular accumulation of abnormal proteins such as α-synuclein and tau is an essential feature of neurodegenerative disorders such as Parkinson disease and fronto-temporal dementia, reduction of protein production is now considered as a viable target for treatment of these and closely related neurodegenerative disorders. Abnormalities in polymerase I activity and rRNA production may also be associated with nuclear and nucleolar stress, DNA damage, and childhood onset neuronal death as is the case for the UBTF E210K neuroregression syndrome. Moreover, restraining the activity of Pol I may be a viable strategy to slow aging. Before starting down the road of Pol I inhibition for treating non-cancerous disorders of the nervous system, many questions must be answered. First, how much Pol I inhibition can neurons tolerate and for how long? Should inhibition of Pol I be continuous or pulsed? Will cells compensate for Pol I inhibition by upregulating the number of active rDNAs? At present, we have no effective and safe disease modulatory treatments for Alzheimer disease, α-synucleinopathies, or tauopathies, and novel therapeutic targets and approaches must be explored.

This work aimed to study the effect of repeated exposure to low doses of ozone on alpha-synuclein and the inflammatory response in the substantia nigra, jejunum, and colon. Seventy-two male Wistar rats were divided into six groups. Each group received one of the following treatments: The control group was exposed to air. Ozone groups were exposed for 7, 15, 30, 60, and 90 days for 0.25 ppm. for four hours daily. Afterward, they were anesthetized, and their tissues were extracted and processed using western blotting, immunohistochemistry, and qPCR. The results indicate a significant increase in alpha-synuclein in the substantia nigra and jejunum from 7 to 60 days of exposure, an increase in NFκB from 7 to 90 days in the substantia nigra, while in the jejunum, a significant increase is observed at 7 and 15 days and a decrease at 60 and 90 days for the colon. Interleukin IL-17 shows an increase at 90 days in the substantia nigra in the jejunum and increases at 30 days and in the colon at 15 and 90 days. Exposure to ozone increases the presence of al-pha-synuclein and the loss of regulation of the inflammatory response, which contributes significantly to degenerative processes.

Cholesterol, a crucial component of cell membranes, influences various biological processes, including membrane trafficking, signal transduction, and host-pathogen interactions. Disruptions in cholesterol homeostasis have been linked to congenital and acquired conditions, including neurodegenerative disorders such as Alzheimer’s disease (AD). Previous research from our group has demonstrated that herpes simplex virus type I (HSV-1) induces an AD-like phenotype in several cell models of infection. This study explores the interplay between cholesterol and HSV-1-induced neurodegeneration. The impact of cholesterol was determined by modulating its levels with methyl-beta-cyclodextrin (MβCD) using the neuroblastoma cell lines SK-N-MC and N2a. We have found that HSV-1 infection triggers the intracellular accumulation of cholesterol in structures resembling endolysosomal/autophagic compartments, a process reversible upon MβCD treatment. Moreover, MβCD exhibits inhibitory effects at various stages of HSV-1 infec-tion, underscoring the importance of cellular cholesterol levels not only in the viral entry pro-cess but also in subsequent post-entry stages. MβCD also alleviated several features of AD-like neurodegeneration induced by viral infection, including lysosomal impairment and intracellu-lar accumulation of amyloid-beta peptide (Aβ) and phosphorylated tau. In conclusion, these findings highlight the connection between cholesterol, neurodegeneration, and HSV-1 infection, providing valuable insights into the underlying mechanisms of AD.

Oxidative neurodegeneration causes various neuronal diseases including Alzheimer's disease, Parkinson's disease, and Huntington's disease. This study aimed to demonstrate the protective effect of leaf extracts of Allium senescens on 6-hydroxydopamine (6-OHDA)-stressed SH-SY5Y cells, known as an optimal cell for neurotoxic research. Levels of apoptotic markers were evaluated using quantitative polymerase chain reaction (qPCR) and flow cytometry. The localization of apoptotic cells in vivo was analyzed using whole-mount immunochemistry and the terminal deoxynucleo-tidyl transferase dUTP nick end labeling assay. Additionally, reactive oxygen species (ROS) pro-duction was estimated using flow cytometry. 6-OHDA induced ROS production in neuroblast cells and in vivo, but treatment with the extract protected against the 6-OHDA-induced increase in ROS levels. Under oxidative stress, the extract performs three protective functions: decreases ROS production, prevents mitochondrial apoptosis, and protects the central and ventral nervous systems. These results also suggest that the extract can be useful for the development of functional foods for the prevention of neural damage due to oxidative stress.

Oxidative stress-mediated cell death is a major cause of dopaminergic neuronal loss in the substantia nigra (SN) of Parkinson’s disease patients. Ergothioneine (ET), a natural dietary compound, has been shown to have cytoprotective functions, but neuroprotective actions against PD have not been well established. 6-Hydroxydopamine (6-OHDA) is a widely used neurotoxin to simulate the degeneration of dopaminergic (DA) neurons in Parkinson's disease. In this study, we investigated the protective effect of ET on 6-OHDA treated iPSC-derived dopaminergic neurons (iDAs) and further confirmed the protective effects in 6-OHDA treated human neuroblastoma SH-SY5Y cells. In 6-OHDA treated cells, metabolic stress in the form of decreased mitochondrial membrane potential (ΔΨm), increased mitochondrial reactive oxygen species (mROS), reduced cellular ATP levels, and increased total protein carbonylation levels was observed. 6-OHDA treatment also significantly decreased tyrosine hydroxylase levels. These effects were significantly abrogated when ET was present. Verapamil hydrochloride (VHCL), a non-specific inhibitor of the ET transporter, OCTN1, abolished ET’s cytoprotective effects, indicative of an intracellular action. These results suggest that ET could be a potential therapeutic for Parkinson’s disease.

A 23-month-old neutered male dog of unknown ancestry presented with a history of progressive neurological signs that included anxiety, cognitive impairment, tremors, seizure activity, ataxia, and pronounced visual impairment. The clinical signs were accompanied by global brain atrophy. Due to progression in the severity of disease signs, the dog was euthanized at 26 months of age. Examination of tissues collected at necropsy revealed dramatic intracellular accumulations of autofluorescent inclusions in the brain, retina, and cardiac muscle. The inclusions were immunopositive for subunit c of mitochondrial ATP synthase, and their ultrastructural appearances were similar to those of lysosomal storage bodies that accumulate in some of the neuronal ceroid lipofuscinosis (NCL) diseases. The also dog exhibited widespread neuroinflammation. Based on these findings, the dog was deemed likely to have suffered from a form of NCL. A whole genome sequence analysis of the proband’s DNA revealed a homozygous C to T substitution that altered the intron 3 – exon 4 splice site of CLN6. Other mutations in CLN6 cause NCL diseases in humans and animals including dogs. CLN6 protein was undetectable with immunolabeling in the tissues of the proband. Based on the clinical history, fluorescence and electron-microscopy, immunohistochemistry, and molecular genetic findings, the disorder in this dog is classified as an NCL resulting from the absence of CLN6 protein. Screening the dog’s genome for a panel of breed-specific polymorphisms indicated that its ancestry included numerous breeds, with no single breed predominating. This suggests that the CLN6 disease variant is likely to be present in other mixed breed dogs and at least some of the ancestral breeds.

Age is the primary risk factor for neurodegenerative diseases such as Alzheimer’s and Huntington’s disease. Alzheimer’s disease is the most common form of dementia and a leading cause of death in the elderly population of the United States. No effective treatments for these diseases currently exist. Identifying effective treatments for Alzheimer’s, Huntington’s, and other neurodegenerative diseases is a major current focus of national scientific resources, and there is a critical need for novel therapeutic strategies. Here we investigate the potential for targeting the kynurenine pathway metabolite 3-hydroxyanthranilic acid (3HAA) using Caenorhabditis elegans expressing amyloid-beta or a polyglutamine peptide in body wall muscle, modeling proteotoxicity in Alzheimer’s and Huntington’s disease-related, respectively. We show that knocking down the enzyme that degrades 3HAA, 3HAA dioxygenase (HAAO) delays age-associated paralysis in both models. This effect on paralysis was independent of protein aggregation in the polyglutamine model. We also show that the mechanism of protection against proteotoxicity from HAAO knockdown is mimicked by 3HAA supplementation, supporting elevated 3HAA as the mediating event liking HAAO knockdown to delayed paralysis. This work demonstrates potential for 3HAA as a targeted therapeutic in neurodegenerative disease, though the mechanism is yet to be explored.