Biology subjects

Dixon, J. E.

Publications and source records attributed to Dixon, J. E..

6 recordsLinked to original sources

bioRxiv2026

Scaffold-mediated delivery of a miRNA-29b mimic mitigates excessive extracellular matrix deposition and matrix contraction in wound healing applications

Disruption of the wound healing cascade can result in pathological outcomes, including fibrosis due to myofibroblast-mediated contraction and collagen deposition. Despite the clinical significance, effective treatments for fibrosis remain limited as current therapies often show inconsistent efficacy, adverse effects, and patient discomfort. Combinatorial therapeutic strategies integrating biomaterial scaffolds with gene delivery have shown promise in regenerative healing. MicroRNAs (miRNAs) are key regulators of fibrotic signalling in cells, including fibroblasts and myofibroblasts. Specifically, miRNA-29b is notable for downregulating pro-fibrotic genes, including collagen type I, reducing ECM accumulation, and limiting fibroblast/myofibroblast overactivation. In this context, the present work develops a collagen-GAG (CG) scaffold platform for delivery of miRNA-29b complexed GET nanoparticles to inhibit fibrosis. Initially, bioinformatic analysis of miRNA-29b validated its involvement in ECM-associated pathways and processes, followed by successful nanoparticle internationalisation in primary dermal fibroblasts. The anti-fibrotic efficacy of the optimised miRNA-29b nanoparticles was subsequently demonstrated by significant reductions in collagen deposition and -SMA expression, both key indicators of myofibroblast differentiation and fibrosis. The optimised miRNA-29b formulation was then incorporated into 3D porous collagen-GAG (CG) scaffolds, which modulated fibrotic gene expression while preserving scaffold structure conducive to fibroblast/myofibroblast infiltration and proliferation. Finally, functional outcomes of seeded TGF-{beta}-stimulated fibroblasts, including reduced matrix contraction, -SMA expression, and ECM deposition, were comparable to those observed in non-fibrotic conditions, thereby confirming the therapeutic potential of scaffold-mediated miRNA-29b delivery. Together, these findings demonstrate that scaffold-mediated miRNA-29b delivery represents a promising anti-fibrotic strategy for wound healing by mitigating myofibroblast activation, limiting matrix contraction, and preventing pathological ECM accumulation.

bioengineering↗

bioRxiv2025

Scaffold-mediated miRNA-155 inhibition promotes regenerative macrophage polarisation leading to anti-inflammatory, angiogenic, and neurogenic responses for wound healing

Chronic wounds represent a significant clinical challenge due to persistent inflammation and impaired nerve regeneration, both of which delay healing. Conventional treatments often yield limited success and inconsistent outcomes, especially in complex and recurring wounds. Combinatorial strategies that integrate biomaterial scaffolds with gene delivery offer a promising approach to promote tissue repair. MicroRNAs (miRNAs), particularly miRNA-155, have emerged as crucial regulators of wound healing. MiRNA-155 is highly expressed in inflammatory conditions and plays a key role in macrophage activation, polarisation, and nerve regeneration. In this context, this study introduces a miRNA-155 inhibitor-activated scaffold designed to modulate the chronic wound environment by inhibiting miRNA-155. MiRNA-155 inhibitor complexed GET nanoparticles were characterised and incorporated into collagen-glycosaminoglycan (CG) scaffolds. These supported dermal fibroblast and endothelial cell growth while enabling controlled inhibitor release. Scaffold-mediated miRNA-155 inhibition in both non-polarised (M0) and pro-inflammatory (M1) macrophages promoted anti-inflammatory (M2) polarisation. Macrophage secretome analysis showed reduced inflammatory cytokines and increased angiogenic growth factor secretion in both conditions. The regenerative potential of the miRNA-i-activated scaffold via macrophage polarisation was validated through inflammatory and angiogenic functional assays with endothelial cells. In parallel, scaffold-mediated miRNA-155 delivery to dorsal root ganglia (DRG) promoted neurogenic outcomes through enhanced axonal regrowth, essential for the synergistic repair of chronic wounds across the skin-nerve axis. In vivo implantation of miRNA-155 inhibitor-activated scaffolds in chicks demonstrated successful integration without disrupting vascular network formation. Collectively, these findings establish the miRNA-155 inhibitor-activated scaffold as a regenerative platform with anti-inflammatory, pro-angiogenic, and neurogenic outcomes, offering a multifaceted solution for chronic wound healing applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC="FIGDIR/small/682055v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1c6a6b6org.highwire.dtl.DTLVardef@eb04f9org.highwire.dtl.DTLVardef@1937f15org.highwire.dtl.DTLVardef@7c70d3_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2021

Ca2+-dependent liquid-liquid phase separation underlies intracellular Ca2+ stores.

Endoplasmic/sarcoplasmic reticulum Ca2+ stores are essential to myriad cellular processes, however, the structure of these stores is largely unknown and existing models do not address all literature observations. We investigate CASQ1 - the major Ca2+ binding protein of skeletal muscle - and discover Ca2+-dependent liquid-liquid phase separation activity. The intrinsic disorder of CASQ1 underlies this activity and is regulated via phosphorylation by the secretory pathway kinase FAM20C. This divalent cation driven condensation demonstrates liquid-liquid phase separation occurs within the endoplasmic/sarcoplasmic reticulum, mechanistically explains efficient Ca2+ buffering and storage, and represents a largely unexplored mechanism of divalent-cation driven protein association.

biochemistry↗

bioRxiv2021

A novel bivalent DNA vaccine encoding both spike protein receptor-binding domain and nucleocapsid protein of SARS-CoV-2 to elicit T cell and neutralising antibody responses that cross react with variants

Although the efficacy of vaccines targeting SARS-CoV-2 is apparent now that the approved mRNA and adenovirus vector vaccines are in widespread use, the longevity of the protective immune response and its efficacy against emerging variants remains to be determined. We have therefore designed a DNA vaccine encoding both the SARS-CoV-2 spike receptorbinding domain ( RBD) and nucleocapsid proteins, the latter of which is highly conserved amongst beta coronaviruses. The vaccine elicits strong pro-inflammatory CD4+ Th1 and CD8+ T-cell responses to both proteins in mice and rats, with responses being significantly enhanced by fusing the nucleocapsid sequence to a modified Fc domain. We have shown that the vaccine also stimulates high titre antibody responses to RBD in mice that efficiently neutralise in pseudotype and live virus neutralisation assays and show cross reactivity with spike proteins from the variants B.1.1.7 (Alpha), B.1.351 (Beta) and B.1.617.2 (Delta). The vaccine also showed good protection in a viral challenge model in ACE2 receptor transgenic mice. This DNA platform can be easily adapted to target variant proteins and we show that a vaccine variant encoding the Beta variant sequence stimulates cross-reactive humoral and T cell responses. These data support the translation of this DNA vaccine platform into the clinic, thereby offering a particular advantage for rapidly targeting emerging SARS-CoV-2 variants.

immunology↗

bioRxiv2019

DYRK2 activates heat shock factor 1 promoting resistance to proteotoxic stress and tumour growth in triple-negative breast cancer

To survive aneuploidy-induced proteotoxic stress, cancer cells activate the proteotoxic-stress response pathway, which is controlled by heat shock factor 1 (HSF1). This pathway supports cancer initiation, cancer progression and chemoresistance and thus is an attractive target. As developing HSF1 inhibitors is challenging, the identification and targeting of upstream regulators of HSF1 presents a tractable alternative strategy. Here we demonstrate that in triple negative breast cancer (TNBC) cells, the dual-specificity tyrosine-regulated kinase 2 (DYRK2) phosphorylates HSF1, promoting its nuclear stability and transcriptional activity. Thus, DYRK2 depletion reduces HSF1 activity and sensitises TNBC cells to proteotoxic stress. Importantly, in tumours from TNBC patients, DYRK2 levels positively correlate with active HSF1 and associates with poor prognosis, suggesting that DYRK2 could be promoting TNBC. In agreement with this, DYRK2 depletion reduces tumour growth in a TNBC xenograft model. These findings identify DYRK2 as both, a key modulator of the HSF1 transcriptional program, and a potential therapeutic target.

cancer biology↗

bioRxiv2018

Ancestral Roles of the Fam20C Family of Secreted Protein Kinases Revealed by Functional Analysis in C. elegans

Fam20C is a secreted protein kinase mutated in Raine syndrome, a human skeletal disorder. In vertebrates, bone and enamel proteins are major Fam20C substrates. However, Fam20 kinases are conserved in invertebrates lacking bone and enamel, suggesting other ancestral functions. We show that FAMK-1, the C. elegans Fam20C ortholog, contributes to fertility, embryogenesis, and development. These functions are not fulfilled when FAMK-1 is retained in the early secretory pathway. During embryogenesis, FAMK-1 maintains inter-cellular partitions and prevents multinucleation; notably, temperature elevation or lowering cortical stiffness reduces requirement for FAMK-1 in this context. FAMK-1 is expressed in multiple adult tissues that undergo repeated mechanical strain, and selective expression in the spermatheca restores fertility. Informatic, biochemical and functional analysis implicate lectins as FAMK-1 substrates. These findings suggest that FAMK-1 phosphorylation of substrates, including lectins, in the late secretory pathway is important in embryonic and tissue contexts where cells are subjected to mechanical strain.

cell biology↗