Biology subjects

Pascoe, C.

Publications and source records attributed to Pascoe, C..

4 recordsLinked to original sources

bioRxiv2026

Plasma-derived extracellular vesicles as potential biomarkers and mediators of functional alterations in MELAS

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is a genetic disorder characterized by progressive neuromuscular and multisystem symptoms. MELAS typically manifests during childhood, can be difficult to diagnose, and has no cure. Extracellular vesicles (EVs) are lipid-enclosed nanoparticles secreted from cells that contain biological cargo and have demonstrated potential as biomarkers. We investigated the potential of plasma-derived EVs as diagnostic biomarkers of MELAS and examined their functional effects on mitochondrial respiration in treated skeletal muscle myotubes. Plasma-derived EVs were isolated from MELAS patients and age- and sex-matched control individuals, and biophysical characteristics and cargo of EVs analyzed. A Mito Stress Test was performed to assess oxygen consumption rate (OCR) in healthy myotubes treated with Control- or MELAS-EVs to determine the functional effects of circulatory EVs. Nine MELAS patients from two families were studied, and the results were categorized by age, sex and mtDNA heteroplasmy level. EV size and zeta potential remained unchanged. However, total EV concentration was higher in MELAS patients, particularly for small-EVs (<200 nm) and in younger patients (<25 years old). Relative protein yield per EV was lower in the MELAS group, especially among female and younger individuals. EV double-stranded DNA (dsDNA) concentration did not differ between MELAS- and Control-EVs overall, but was higher in male MELAS patients. Protein markers typically enriched in small-EVs showed altered expression in MELAS EVs: TSG101 and CD63 were lower, while flotillin-1 was higher compared to Control-EVs. A decrease in basal OCR was shown in cells treated with MELAS-EVs, with a similar response noted in the group treated with EVs from female MELAS patients. Post-treatment analysis showed no differences in oxidative phosphorylation (OXPHOS) subunit levels between cells treated with MELAS- and Control-EVs. In conclusion, plasma-derived EVs show promise as potential biomarkers for MELAS, and circulating EVs in this patient population may contribute to systemic metabolic dysfunction.

Cell Biology↗

bioRxiv2026

Autophagy Cholesterol Axis Remodeling Supports Malignant Progression and Chemoresistance in Glioma

Glioma progression and resistance to temozolomide (TMZ) remain major clinical challenges. Here, we investigated whether dysregulated autophagy and cholesterol metabolism are coordinately remodeled during glioma progression and TMZ resistance. Tissue microarray analysis of astrocytoma and glioblastoma specimens revealed progressive autophagosome accumulation, reflected by increased LC3{beta} puncta, coupled with impaired autophagic flux compared with adjacent normal brain tissue. These alterations intensified with tumor grade and were associated with upregulation of farnesyl diphosphate synthase (FDPS), linking malignant progression to cholesterol pathway remodeling. TMZ-resistant (R) glioblastoma cells exhibited epithelial-to-mesenchymal transition, mitotic quiescence, and mitochondrial remodeling consistent with a therapy-tolerant phenotype. Bioenergetic profiling demonstrated reduced respiratory reserve, diminished ATP-linked respiration, and elevated proton leak, indicating constrained metabolic flexibility. In parallel, impaired autophagy flux was associated with suppression of de novo cholesterol synthesis and transcriptional downregulation of SREBP-2 and LDL-R. Comprehensive lipidomic profiling revealed marked cholesterol metabolic reprogramming in R cells, characterized by accumulation of specific cholesteryl esters, including CE 22:5, CE 22:6, CE 22:4, and CE 20:4, despite reduced cholesterol biosynthesis. Pharmacologic inhibition of the mevalonate pathway with simvastatin significantly altered cholesteryl ester profiles but failed to restore autophagy flux or sensitize R cells to TMZ-induced apoptosis, even under combined TMZ-simvastatin treatment. Lay AbstractAs gliomas progress from astrocytoma to glioblastoma, autophagy becomes dysregulated and cholesterol metabolism is rewired. This coordinated remodeling supports tumor survival, metabolic plasticity, and resistance to temozolomide therapy. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/697885v2_ufig1.gif" ALT="Figure 1000"> View larger version (79K): org.highwire.dtl.DTLVardef@1183dd2org.highwire.dtl.DTLVardef@82e20dorg.highwire.dtl.DTLVardef@c6c8dforg.highwire.dtl.DTLVardef@adb427_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsAutophagy flux blockade intensifies during progression from astrocytoma to glioblastoma Dysregulated autophagy is coupled to altered cholesterol metabolism in malignant gliomas TMZ-resistant glioblastoma cells undergo epithelial-to-mesenchymal transition and mitotic quiescence Resistant cells exhibit constrained bioenergetic capacity and mitochondrial remodeling Impaired autophagy suppresses de novo cholesterol synthesis and lipid recycling Lipidomics reveals accumulation of long-chain cholesteryl esters in TMZ-resistant cells Statin-based cholesterol inhibition fails to resensitize glioblastoma cells to temozolomide

cancer biology↗

bioRxiv2025

LL-37 and citrullinated-LL-37 enhance disparate oxylipins: LL-37-mediated chemokine response is dependent on COX-2 and the P2X7 receptor in human bronchial epithelial cells

BackgroundDuring airway inflammation, chemokines, oxylipins (bioactive lipids) and cationic host defence peptides (CHDP) are enhanced in the lungs. However, the interplay of these molecules in the process of airway inflammation is not fully resolved. The human cathelicidin CHDP, LL-37, can enhance the expression of chemokines which is turn facilitates influx of leukocytes into the lungs. Moreover, LL-37 can get citrullinated during inflammation and the effect of this post-translational modification on LL-37-mediated immunomodulatory functions remains unclear. Therefore, in this study we aimed to define the impact of LL-37 and citrullinated-LL-37 (citLL-37) on oxylipins and its association with downstream chemokine production in human bronchial epithelial cells (HBEC), and its functional impact on leukocyte influx. MethodsWe used a lipidomics approach to identify oxylipins that are enhanced in response to LL-37 and citLL-37 in HBEC. We further examined the role of selected oxylipins in LL-37- and citLL-37-mediated chemokine production by ELISA, and related leukocyte migration using a transwell migration assay. ResultsWe showed that LL-37, but not citLL-37, enhances oxylipins that are known to promote inflammation such as prostaglandins regulated by the cyclooxygenase (COX pathway). Although both LL-37 and citLL-37 upregulated COX-2, LL-37-mediated increase in COX-2 expression was significantly higher than that mediated by citLL-37. We showed that upregulation of COX-2 expression was dependent on the P2X7 purinergic receptor. Our mechanistic studies revealed that LL-37-mediated increase in chemokines, GRO, IL-8 and MIP-3, was dependent on the COX-2 pathway. Our results also indicated that COX-2-induced PGE2 may act in an autocrine manner signaling through its EP receptors to facilitate LL-37-induced chemokine production. We functionally confirmed that factors secreted from HBEC in response to LL-37, but not citLL-37, promotes neutrophil migration which is COX-2 dependent. ConclusionThe results of this study indicate that pro-inflammatory responses mediated by LL-37 is alleviated by citrullination of the peptide. These findings suggest that citrullination of LL-37 may be a post-translational regulatory mechanism to control inflammation. Overall, this study underscores the role of LL-37 in influencing the enhancement of bioactive lipids and metabolic pathways such as COX-2 and its link to the peptide-mediated immunomodulatory functions in the lungs.

immunology↗

bioRxiv2023

Novel DNA methylation changes in mouse lungs associated with heavy smoking

Smoking is a potent cause of asthma, chronic obstructive pulmonary disease (COPD) and many other health defects, and changes in DNA methylation (DNAm) have been identified as a potential link between smoking and these health outcomes. However, most links between smoking and DNAm have been made using blood and other easily accessible tissues in humans, while evidence from more directly affected tissues such as the lungs is greatly lacking. Here, we identified DNAm patterns which are altered by smoking directly in the lungs. We used a well-established mouse model to measure the effects of heavy smoking first on lung phenotype immediately after smoking and then after a period of smoking cessation. Next, we determined whether our mouse model could recapitulate previous DNAm patterns observed in smoking humans by measuring DNAm at a candidate gene responsive to cigarette smoke (CS), Cyp1a1. Finally we carried out epigenome-wide DNAm analyses using the newly released Illumina mouse methylation microarrays. Our results recapitulate some of the phenotypes and DNAm patterns observed in human studies but reveal 32 differentially methylated genes specific to the lungs which have not been previously associated with smoking. The affected genes are known to be involved in nicotine dependency, tumorigenesis and metastasis, immune cell dysfunction, lung function decline, and COPD. This research emphasizes the need to study CS-mediated DNAm signatures in directly affected tissues like the lungs, as that may be essential in understanding mechanisms underlying CS-mediated health outcomes.

molecular biology↗