Biology subjects

Dalton, C.

Publications and source records attributed to Dalton, C..

5 recordsLinked to original sources

bioRxiv2025

Prion shedding is reduced by chronic wasting disease vaccination

Chronic wasting disease (CWD) is a strictly fatal and highly contagious prion disease of wild and farmed cervids currently expanding in North America. Prion diseases are caused by conversion of the cellular prion protein to its pathological isoform PrPSc. Vaccination is considered a promising strategy to contain CWD, even though prion diseases do not show classical immune responses. For CWD containment, it is important that vaccines reduce shedding of prions in excreta, a major contributor to transmission. Here, we tested the effect of vaccines on prion shedding in feces and urine by vaccinating and prion infecting knock-in mice that recapitulate CWD pathogenesis as found in cervids. Vaccination reduced or even prevented CWD shedding in feces and urine collected between 30-90% of incubation time to disease. This is the first report showing that prion shedding can be blocked in a prion disease. For CWD specifically it may reduce the environmental prion burden and break the disease transmission cycle.

neuroscience↗

bioRxiv2025

The molecular mechanism of uptake and cell-to-cell transmission of arginine-containing dipeptide repeat proteins.

Micro-satellite repeat expansion of the 5 GGGGCC 3 sequence in the C9orf72 gene is the most common monogenic form of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Dipeptide repeat proteins (DPRs) translated from the mutant allele can be detected in postmortem brains of afflicted individuals. The arginine containing peptides, poly-PR and poly-GR, are particularly noxious to cells. Both have been shown to undergo cell-cell transmission, but the underlying mechanisms are not understood. We found rapid internalization and nucleolar localization of bath-applied hemagglutinin (HA) tagged poly-PR with twenty repeats (HA-PR20) in cell lines and neurons. Small molecule and RNAi approaches implicated a temperature-dependent, fluid phase endocytosis mechanism in HA-PR20 uptake. We sought to identify DPR-related cell surface uptake factors using a high-resolution proximity labeling technique developed in the MacMillan group, termed {micro}Map. DPR-iridium conjugates identified candidate cell-surface proteins which were interrogated in an RNAi screen. Focusing on our strongest candidate, chondroitin sulfate proteoglycan 4 (CSPG4), we showed that cellular uptake of HA-PR20 is blocked by inhibition of glycosaminoglycan chain synthesis (using drugs or RNAi) and knockdown or ablation of CSPG4 (using RNAi or CRISPR editing). Reduction of CSPG4 protected PR20-induced neuronal toxicity. We used a dual reporter system to interrogate in vitro neuron-to-neuron transmission of PR50 and found that PR50 synthesized by one neuron readily spread to neighboring neurons. Transmission was significantly reduced when CSPG4 was knocked down. These results suggest CSPG4 is an important factor in poly-PR internalization and transmission and therefore may be a therapeutic target to slow DPR transmission and disease progression. Significance StatementA GGGGCC hexanucleotide repeat expansion in the C9orf72 gene is the most common monogenic form of ALS/FTD. This expansion leads to dipeptide repeat protein (DPR) production through non-canonical translation of repeat-containing RNA. DPRs have been shown to transmit between cells, but how this occurs is not well understood. We identified the cell surface protein chondroitin sulfate proteoglycan 4 (CSPG4) as a mediator of the uptake and intercellular spread of toxic arginine-rich DPRs. Targeting CSPG4 may provide a strategy to block DPR transmission and slow disease progression.

neuroscience↗

bioRxiv2025

Mosaic pattern: lung functional heterogeneity at the alveolus level

Inhaled particles carrying pathogens, pollutants (e.g., microplastics, smoke), therapeutics, and diagnostics are increasingly relevant to public health, yet real-time tracking of aerosol transport in functional alveoli remains challenging. Here, we used the recently developed crystal ribcage to investigate aerosol transport in ex vivo lungs during active ventilation, obtaining the first real-time observations of single aerosol droplet transport and deposition in functional alveoli. We discovered deterministic heterogeneity at both intra- and inter-alveolar levels, with aerosol distribution forming a characteristic "mosaic" pattern in which only specific alveolar clusters received particles. The pattern was consistently formed in vivo during spontaneous breathing and ex vivo using both positive- and negative-pressure ventilation. This pattern was also consistent across a range of aerosols, including small molecules, nanobodies, nanoparticles, microplastics, therapeutics, and pathogens. Additionally, the pattern was observed in murine, porcine, and human lungs, and evolved from birth through aging in mice. The post-deposition stability of the pattern depended on particle type and lung age, lasting from a few minutes for small molecular weight particles to multiple days for cell-binding particles. These alveolar-level heterogeneities may uncover previously unrecognized biological and immunological heterogeneities associated with the mosaic pattern, including its role in postnatal lung development, susceptibility to inhaled airborne hazards such as pollutants and infectious agents, and early pathogenesis and response to inhaled therapeutics in respiratory diseases such as pneumonia, COPD, asthma, and lung cancer.

bioengineering↗

bioRxiv2025

Ubiquitin Proteasome System Components, RAD23A and USP13, Modulate TDP-43 Solubility and Neuronal Toxicity

At autopsy, >95% of ALS cases display a redistribution of the essential RNA binding protein TDP-43 from the nucleus into cytoplasmic aggregates. The mislocalization and aggregation of TDP-43 is believed to be a key pathological driver in ALS. Due to its vital role in basic cellular mechanisms, direct depletion of TDP-43 is unlikely to lead to a promising therapy. Therefore, we have explored the utility of identifying modifier genes that modify its mislocalization or aggregation. We have previously shown that loss of rad-23 improves locomotor deficits in TDP-43 C. elegans models of disease and increases the degradation rate of TDP-43 in cellular models. To understand the mechanism through which these protective effects occur, we generated an inducible mutant TDP-43 HEK293 cell line. We find that knockdown of RAD23A reduces insoluble TDP-43 levels in this model and primary rat cortical neurons expressing human TDP-43A315T. Utilizing a discovery-based proteomics approach, we then explored how loss of RAD23A remodels the proteome. Through this proteomic screen, we identified USP13, a deubiquitinase, as a new potent modifier of TDP-43 induced aggregation and cytotoxicity. We find that knockdown of USP13 reduces the abundance of sarkosyl insoluble mTDP-43 in both our HEK293 model and primary rat neurons, reduces cell death in primary rat motor neurons, and improves locomotor deficits in C. elegans ALS models. Significance StatementAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease (NDD) with no effective therapies. The mislocalization and aggregation of TAR DNA binding protein 43 (TDP-43) is a key pathological marker of ALS and other NDDs. Due to its vital functions, targeted therapeutic reduction of TDP-43 could be problematic. Here, we have explored the utility of targeting modifier genes. We find that knockdown of two members of the ubiquitin proteasome system, RAD23A and USP13, enhance TDP-43 solubility and decrease TDP-43 induced neurotoxicity.

neuroscience↗

bioRxiv2021

Neurons undergo pathogenic metabolic reprograming in models of familial ALS

Normal cellular function requires a rate of ATP production sufficient to meet demand. In most neurodegenerative diseases (including Amyotrophic Lateral Sclerosis, ALS), mitochondrial dysfunction is postulated raising the possibility of impaired ATP production and a need for compensatory maneuvers to sustain the ATP production/demand balance. We find in our rodent models of familial ALS (fALS), impairment in neuronal glycolytic flux with maintained or enhanced activity of the citric acid cycle. This rewiring of metabolism is associated with normal ATP levels and redox status, supporting the notion that mitochondrial function is not compromised in neurons expressing fALS genes. Genetic loss-of-function manipulation of individual steps in the glycolysis and the pentose phosphate pathway blunt the negative phenotypes seen in various fALS models. We propose that neurons adjust fuel utilization in the setting of neurodegenerative disease-associated mitochondrial dysfunction in a baleful manner and targeting this process can be healthful.

neuroscience↗