Biology subjects

Dillon, E.

Publications and source records attributed to Dillon, E..

7 recordsLinked to original sources

bioRxiv2026

NOTCH3 Modulation of Extracellular Matrix, Cytoskeletal Organisation and Metabolic Functions in Human Vascular Smooth Muscle Cells

NOTCH3 is a transmembrane receptor highly expressed in vascular mural cells where it contributes to blood vessel formation and homeostasis. NOTCH3 expression declines in the vasculature with aging, and dysregulated NOTCH3 signalling is implicated in pulmonary arterial hypertension, cancer progression and CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy). RNA-based approaches targeting NOTCH3 are emerging as potential therapeutic strategies, however, the consequences of NOTCH3 suppression in mature vascular smooth muscle cells (VSMCs) remain incompletely understood. Here, we investigated the molecular and functional effects of siRNA-mediated NOTCH3 knockdown in human aortic smooth muscle cells. Transfection with NOTCH3-targeting siRNA efficiently suppressed NOTCH3 transcript and protein levels. Quantitative proteomics revealed remodelling of extracellular matrix (ECM), cytoskeletal and metabolic pathways, with enrichment of collagen biosynthesis and inhibition of glycolytic signalling. Specifically, NOTCH3 knockdown increased ECM components, including COL3A1, elevated F-actin, and upregulated the actin regulator, CTTN. In parallel, glycolytic capacity was reduced, accompanied by decreased expression of the glycolytic enzyme ENO2. Despite reduced VEGFA and alteration in angiogenic signalling proteins, endothelial network formation in co-cultures, as well as VSMC proliferation and migration remained unaffected. Finally, NOTCH3 interactome analysis revealed key collagen and actin-regulating proteins. These findings identify NOTCH3 as an important regulator of ECM homeostasis, cytoskeletal organisation, and glycolytic metabolism. The preservation of primary cellular functions despite molecular remodelling highlights the adaptive capacity of VSMCs. These findings demonstrate that therapeutic modulation of NOTCH3 may alter vascular cell biology which warrants consideration during development of RNA-based therapeutics for CADASIL and other NOTCH3-associated diseases.

molecular biology↗

bioRxiv2026

Divergent Pathogenic PR-DUB Complex Variants Converge Functionally Via PRC2 Displacement From Chromatin

The PR-DUB complex is responsible for erasing the repressive histone modification, H2AK119ub1. ASXL1-3 proteins are mutually exclusive catalytic partners of BAP1 in the PR-DUB complex. Somatic heterozygous ASXL1-3 variants are associated with cancer, including myeloid malignancies, while de novo germline variants cause neurodevelopmental disorders such as Bohring-Opitz syndrome. These pathogenic variants are almost exclusively nonsense and frameshift and have been proposed to act as gain-of-function. However, the precise catalytic impact and mechanism of variant ASXL1-3 remains elusive. Using an isogenic embryonic stem cell model we have discovered that ASXL1 BOS variants drive reductions - but not global ablations - in H2AK119ub1, consistent with gain-of-function. This catalytic change occurs through the production of a truncated ASXL1 protein with enhanced stability. Hyper-stabilised ASXL1 drives a stoichiometric shift in PR-DUB assembly away from ASXL2 complexes. The drop in H2AK119ub1 levels ultimately reduces PRC2 binding and H3K27me3 deposition. Surprisingly, this phenotype is shared across PR-DUB loss-of-function models and indeed is emerging as a common phenotype across genetically and mechanistically distinct Polycomb-related chromatinopathies.

genetics↗

bioRxiv2025

Protease secreting Nannochloropsis limnetica can valorise invasive plants through circular water-use and accumulate neutral lipids

AO_SCPLOWBSTRACTC_SCPLOWNannochloropsis limnetica can be cultivated on a wide range of effluents and generate high value lipids. Using a fed-batch system, this microalgae was used to demonstrate circular reuse of water to valorise protein depleted fractions (PDF) generated from Gorse leaf protein concentrate (LPC) production. Protein, phenolics and sugar content in the PDF was measured over seven days and corresponding microalgal lipid content was profiled. Extracellular protease activity was also screened to understand how N. limnetica digests and utilises proteins in the medium. A signal peptide-based approach predicted seven proteases expected to be secreted. N. limnetica could rapidly deplete nutrients (ksugar=0.20 {+/-} 0.06 day-1 and kproteins=0.17 {+/-} 0.04 day-1) from the wastewater which could be reused for subsequent LPC extraction processes without any impact on recovery or purity. Phenolics levels remained unaffected during microalgal growth and accumulated in the water across each extraction cycle. Microalgal neutral lipid content ([~]132.8 mglipid g-1 ) was higher in the effluent compared to standard BBM ([~]114.5 mglipid g-1 ). Casein agar plates and 1D zymogram confirmed extracellular protease production by N. limnetica, although their identities remains unclear owing to conflicting / fragmented data from the LC/MS analysis. This work shows that N. limnetica is able to secrete proteases to digest and utilise residual proteins in the medium, and can be employed to valorise agricultural wastewater. Identification of the proteases will require further investigation. HighlightsO_LIN. limnetica can rapidly deplete residual nutrients from LPC effluents. C_LIO_LIN. limnetica accumulates higher neutral lipids with LPC effluents versus BBM. C_LIO_LIN. limnetica secretes extracellular proteases to digest proteins in the medium. C_LIO_LIWater can be circularly reused between LPC production and N. limnetica cultivation. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/691304v2_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@1524de0org.highwire.dtl.DTLVardef@76cea1org.highwire.dtl.DTLVardef@1f7ad4aorg.highwire.dtl.DTLVardef@191f929_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2025

AEBP2-Directed H3K27me2 Defines a Specific Vulnerability in EZH2-mutant Lymphoma

The catalytic subunit of Polycomb Repressive Complex 2 (PRC2), EZH2, is recurrently mutated in 25% of diffuse large B-cell lymphomas (DLBCL), causing increased H3K27me3 and decreased H3K27me2 levels. EZH2 inhibitors provide clinical benefit, but resistance frequently develops, highlighting the need for alternative therapeutic targets. Here, we identify the PRC2 accessory protein AEBP2 as a specific genetic dependency in EZH2-mutant DLBCL. While AEBP2 acts through PRC2, its essential role is surprisingly independent of canonical H3K27me3-mediated gene silencing. Instead, AEBP2 functions within a PRC2.2 complex lacking JARID2, using its zinc-finger domains to sample intergenic chromatin to sustain H3K27me2. Notably, loss of AEBP2 or NSD2 caused contrasting changes in intergenic H3K27me2 levels, driving sensitivity or resistance to PRC2 inhibitors, respectively. Our findings identify AEBP2-PRC2.2-maintained intergenic H3K27me2 as a therapeutic vulnerability in EZH2-mutant DLBCL and highlight dysregulated H3K27me2 as an underappreciated form of PRC2 dysfunction in cancer, with important therapeutic implications.

cancer biology↗

bioRxiv2025

A GPVI-platelet-neutrophil-NET axis drives systemic sclerosis

Systemic sclerosis (SSc) is immune-mediate inflammatory disease characterized by progressive tissue fibrosis. We observed that circulating neutrophils from patients with diffuse SSc exhibit an activated phenotype, a finding echoed in blood and skin transcriptomes. Neutrophil depletion abrogated experimental SSc induced by cutaneous injection of hypochlorous acid (HOCl) or bleomycin (BLM), and adoptive transfer of HOCl and BLM neutrophils induced skin and lung fibrosis in healthy mice, establishing neutrophils as necessary and sufficient for fibrosis. We noted that SSc patients exhibited platelet activation, a phenotype that preceded neutrophil activation in mice, suggesting an upstream role. Indeed, platelet depletion abrogated neutrophil activation and tissue fibrosis, and exposure to HOCl or BLM platelets conferred upon wild-type neutrophils the capacity to induce skin and lung fibrosis via neutrophil extracellular traps (NETs). Genetic and therapeutic blockade of the platelet collagen receptor GPVI attenuated platelet and neutrophil activation, reduced circulating NETs, and protected animals from skin and lung fibrosis. These findings identify the GPVI-platelet-neutrophil-NET as a new source of therapeutic targets in SSc.

immunology↗

bioRxiv2023

A genetic code change in progress: tRNA-Leu(CAG) is conserved in most Saccharomycopsis yeast species but is non-essential and does not compete with tRNA-Ser(CAG) in translation

In the yeast genera Saccharomycopsis and Ascoidea, nuclear genes use a non-standard genetic code in which CUG codons are translated as serine instead of leucine, due to a tRNA-Ser with the unusual anticodon CAG. However, some species in this CUG-Ser2 clade also contain an ancestral tRNA-Leu gene with the same anticodon. One of these species, Ascoidea asiatica, has been shown to have a stochastic proteome in which proteins contain approximately 50% Ser and 50% Leu at CUG codon sites, whereas previously examined Saccharomycopsis species translate CUG only as Ser. Here, we investigated the presence, conservation, and possible functionality of the tRNA-Leu(CAG) gene in the genus Saccharomycopsis. We analyzed the genomes of 33 strains, including almost all known species of Saccharomycopsis, and found that most of them contain both tRNA-Ser(CAG) and tRNA-Leu(CAG) genes. The tRNA-Leu(CAG) gene is evolving faster than tRNA-Ser(CAG) and it has been lost in two species, S. microspora and S. synnaedendra. We deleted the single tRNA-Leu(CAG) gene in S. capsularis and found that it is not essential. Bioinformatic analysis suggested that some CUG codon sites in Saccharomycopsis species may be translated as Leu, specifically in genes with functions in meiosis or sporulation, but mass spectrometry of sporulating S. capsularis and S. fermentans cultures showed only CUG-Ser translation. Cloverleaf structures of tRNA-Leu(CAG) from all Saccharomycopsis species contain mutations that are likely to make them non-functional in translation, but the evolutionary conservation of the gene leads us to propose that it has been retained for an unknown non-translational role.

evolutionary biology↗

bioRxiv2019

Defining variation in pre-human ecosystems can guide conservation: An example from a Caribbean coral reef

There is a consensus that Caribbean coral reefs are a pale shadow of what they once were, yet a reef’s pre-human state is typically assumed or estimated using space-for-time substitution approaches. These approaches may fail to account for past variation before human impact which could mislead conservation priorities and actions. In this study we use a suite of fossilised mid-Holocene (7.2-5.6 ka) fringing reefs in Caribbean Panama to define the Historical Range of Variation (HRV) in coral community structure before human-impact to provide context for the states of modern reefs in the same area. Using the abundances of coral taxa to quantify communities, we found that most of the modern coral communities exist in novel ecosystem states with no fossil precedence. We do however identify one modern reef that is indistinguishable in coral community structure from the mid-Holocene reefs. Reef-matrix cores show that the community on this reef has remained in a stable state for over 760 years, suggesting long-term resistance to the region-wide shift to novel states. Without historical context this robust and stable reef would be overlooked since it does not fulfil expectations of what a “pristine” coral reef should look like. This example illustrates how defining past variation using the fossil record can place modern degradation in historical context and improve conservation recommendations.View Full Text

paleontology↗