Linking Enzyme Upregulation to Autophagic Failure: A Potential Biomarker for GM1 Gangliosidosis

Smith, S.; Larsen, J.

doi:10.1101/2020.10.28.359083

Home/Archive/bioRxiv

bioRxiv · 10.1101/2020.10.28.359083

Linking Enzyme Upregulation to Autophagic Failure: A Potential Biomarker for GM1 Gangliosidosis

Smith, S.·Larsen, J.

View original source ↗Export metadata ↓

Abstract

With an increasing aging population, neurodegenerative diseases are having an increased impact on society. Typically, these diseases are diagnosed significantly past symptom onset, decreasing the possibility of effective treatment. A non-invasive biomarker and specific target are needed to diagnose and treat the disease before late-stage symptoms. GM1 Gangliosidosis is a lysosomal storage disease where lysosomal enzyme {beta}-galactosidase is missing. As a result, GM1 ganglioside is not broken down and accumulates in the cell, ultimately leading to cell death. One of the main aspects of GM1 Gangliosidosis, and other neurodegenerative diseases, is impaired autophagy: reduced fusion of autophagosomes and lysosomes to degrade cellular waste. In this paper, we show that healthy cells (NSV3) have approximately 13 times more co-localization of lysosomes and autophagosomes than GM1 Gangliosidosis-diseased cells (GM1SV3), as demonstrated via immunofluorescence. GM1SV3 fold normal enzyme activity of {beta}-galactosidase was downregulated while mannosidase, and hexosaminidase A were both upregulated. When inducing impaired autophagy in NSV3 via starvation, co-localization gradually decreases with increased starvation time. Most notably, after 48-hour starvation, healthy cells (NSV3) showed no significant difference in co-localization compared to GM1SV3. NSV3 under starvation conditions showed a significant increase between time starved and fold normal enzyme activity, with a positive correlation being observed. Activities of mannosidase, and hexosaminidase A of starved NSV3 closely resemble, and surpass, GM1SV3 after 12-hour starvation. These observations have the potential to expand the conversation regarding impaired autophagy as a potential biomarker for disease progression and diagnostics and as a treatment target.

Explore related subjects

pathology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Smith, S., Larsen, J.. 2020-10-28. Linking Enzyme Upregulation to Autophagic Failure: A Potential Biomarker for GM1 Gangliosidosis. https://doi.org/10.1101/2020.10.28.359083

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

NAE1-Dependent Protein Neddylation Preserves Endothelial Identity and Vascular Integrity

Background: Endothelial dysfunction is a central driver of cardiovascular and inflammatory diseases, yet the post-translational mechanisms that preserve endothelial homeostasis remain incompletely understood. Protein neddylation, the covalent conjugation of a ubiquitin-like modifier, regulates diverse cellular processes, yet its physiological role in the vascular endothelium remains unknown. This study investigated whether protein neddylation is required to preserve endothelial identity and vascular homeostasis. Methods: We generated tamoxifen-inducible endothelial-specific Nae1 knockout mice to inhibit neddylation and combined bulk RNA sequencing, single-cell and single-nucleus transcriptomics, quantitative proteomics, biochemical analyses, and gain- and loss-of-function approaches to define the role of endothelial neddylation in vascular homeostasis and inflammatory injury. Results: Endothelial-specific Nae1 deletion caused rapid mortality associated with vascular leakage, platelet accumulation, inflammation, and multi-organ injury. Multi-omics analyses demonstrated profound loss of endothelial identity, characterized by suppression of core endothelial programs and activation of inflammatory, procoagulant, and pyroptotic pathways. Single-cell analyses revealed progressive endothelial dysfunction culminating in depletion of the endothelial population and remodeling of the vascular niche. Mechanistically, endothelial neddylation deficiency activated gasdermin D (GSDMD)- and gasdermin E (GSDME)-dependent pyroptosis, whereas dual inhibition of GSDMD and GSDME markedly attenuated inflammatory transcriptomic remodeling, vascular injury, hepatocyte death, immune cell infiltration, and platelet accumulation. Translational analyses demonstrated reduced endothelial neddylation in experimental endotoxemia and decreased expression of neddylation pathway components in human atherosclerosis and COVID-19 datasets. Conversely, restoration of endothelial neddylation partially reversed inflammatory endothelial transcriptomic reprogramming in vivo. Conclusions: NAE1-dependent protein neddylation is an essential regulator of endothelial identity and vascular integrity. Loss of endothelial neddylation promotes gasdermin-dependent pyroptosis and thrombo-inflammatory vascular injury, whereas restoration of the neddylation pathway mitigates inflammatory endothelial dysfunction. These findings identify endothelial neddylation as a fundamental mechanism maintaining vascular homeostasis and a potential therapeutic target for cardiovascular and inflammatory diseases.

pathology↗

bioRxiv2021

Contemporary clinical isolates of Staphylococcus aureus from pediatric osteomyelitis patients display unique characteristics in a mouse model of hematogenous osteomyelitis

Osteomyelitis can result from the direct inoculation of pathogens into bone during injury or surgery, or from spread via the bloodstream, a condition called hematogenous osteomyelitis (HOM). HOM disproportionally affects children, and more than half of cases are caused by Staphylococcus (S.) aureus. Laboratory models of osteomyelitis mostly utilize direct injection of bacteria into the bone or the implantation of foreign material, and therefore do not directly interrogate the pathogenesis of pediatric hematogenous osteomyelitis. In this study, we inoculated mice intravenously and characterized resultant musculoskeletal infections using two strains isolated from adults (USA300-LAC and NRS384) and five new methicillin-resistant S. aureus isolates from pediatric osteomyelitis patients. All strains were capable of creating stable infections over five weeks, although the incidence varied. Micro-computed tomography (microCT) analysis demonstrated decreases in trabecular bone volume fraction but little effect on bone cortices. Histologic assessment revealed differences in the precise focus of musculoskeletal infection, with varying mixtures of bone-centered osteomyelitis and joint-centered septic arthritis. Whole genome sequencing of three new isolates demonstrated distinct strains, two within the USA300 lineage and one USA100 isolate. Interestingly, the USA100 strain showed a distinct predilection for septic arthritis, compared to the USA300 strains, including NRS384 and LAC, which more frequently led to osteomyelitis or mixed bone and joint infections. Collectively, these data outline the feasibility of using pediatric osteomyelitis clinical isolates to study the pathogenesis of HOM in murine models and lay the groundwork for future studies investigating strain-dependent differences in musculoskeletal infection. ImportanceThe inflammation of bone tissue is called osteomyelitis, and more than half of cases are caused by an infection with the bacterium Staphylococcus aureus. In children, the most common route of infection is hematogenous, wherein bacteria seed the bone from the bloodstream without another known site of infection. Although these infections pose a significant health problem, they are understudied in the laboratory because of a dearth of robust animal models. In this study, we utilized several previously uncharacterized clinical isolates of S. aureus derived from children with bone infections to generate reproducible and stable musculoskeletal infection in mice with many features seen in human osteomyelitis, making them a valuable resource for future mechanistic and therapeutic studies.

pathology↗

bioRxiv2021

Brain Iron Imaging Markers in the Presence of White Matter Hyperintensities

PurposeTo investigate the relationship between pathological brain iron deposition and white matter hyperintensities (WMHs) in cerebral small vessel disease (CSVD), via Monte Carlo simulations of magnetic susceptibility imaging and a novel imaging marker called the Expected Iron Coefficient (EIC). MethodsA synthetic pathological model of a different number of impenetrable spheres at random locations was employed to represent pathological iron deposition. The diffusion process was simulated with a Monte Carlo method with adjustable parameters to manipulate sphere size, distribution, and extracellular properties. Quantitative susceptibility mapping (QSM) was performed in a clinical dataset to study CSVD to derive and evaluate QSM, R2*, the iron microenvironment coefficient (IMC), and EIC in the presence of WMHs. ResultsThe simulations show that QSM signals increase in the presence of increased tissue iron, confirming that the EIC increases with pathology. Clinical results demonstrate that while QSM, R2*, and the IMC do not show differences in brain iron, the EIC does in the context of CSVD. ConclusionThe EIC is more sensitive to subtle changes in brain iron deposition caused by pathology, even when QSM, R2*, and the IMC do not.

pathology↗