Biology subjects

Renton, M. C.

Publications and source records attributed to Renton, M. C..

6 recordsLinked to original sources

bioRxiv2026

Vascular endothelial cadherin remodeling is associated with endothelial barrier dysfunction in chronic subdural hematoma

Abstract Background: Chronic subdural hematoma (cSDH) remains a significant and increasingly prevalent cause of morbidity in older adults. Disease progression is sustained by de novo formed highly vascularized pseudomembranes and a persistent cycle of fluid accumulation and hematoma expansion. Although inflammatory and angiogenic pathways have been implicated in cSDH pathogenesis, the endothelial mechanisms underlying persistent vascular leak remain poorly understood. We investigated the cSDH vascular microenvironment in human patients and examined the role of vascular endothelial cadherin (VECAD) remodeling in cSDH endothelial dysfunction. Methods: Human cSDH membranes and fluid were evaluated by multiplex profiling, histology, immunofluorescence, immunoprecipitation, western blotting and exploratory bulk RNA sequencing. A human brain endothelial cell (HBEC) line was exposed to patient-derived cSDH fluid to assess VECAD remodeling, endothelial barrier permeability, and proliferation. Results: Multiplex profiling of patient-derived cSDH fluid detected mediators associated with endothelial cell (EC) activation, extracellular matrix remodeling, inflammation, and angiogenesis. In patient pseudomembranes, discontinuous VECAD coincided with erythrocyte extravasation. Two hyperdense (high-risk) specimens showed more extensive disruption than the hypodense (low-risk) specimen while vessel counts appeared similar. Bulk RNA sequencing identified an angiogenic environment and enrichment in cadherin regulation. A soluble VECAD (sVECAD) isoform was detected in cSDH fluid. Exposure of HBECs to patient-derived cSDH fluid increased EC proliferation, cytoplasmic VECAD (cVECAD) accumulation, and EC barrier permeability. Concurrent dexamethasone or minocycline treatment attenuated VECAD cleavage. Conclusions: VECAD disruption is a prominent feature of cSDH and is associated with EC barrier dysfunction. These findings support further evaluation of soluble VECAD as a candidate biomarker and of junction-preserving pathways as potential therapeutic targets.

pathology↗

bioRxiv2025

A connexin 43 targeting peptide prevents blood vessel neointima formation

The gap junction protein connexin 43 (Cx43) is associated with human pathological vascular smooth muscle cell (SMC) proliferation and neointima formation. We previously identified mitogen-activated protein kinase (MAPK) phosphorylation of Cx43 results in binding with the cell cycle protein cyclin E, facilitating neointima formation in mice. However, the specific nature of these interactions and their relevance to human disease have not been elucidated. Using an ex vivo human saphenous vein model of neointima formation, we identified increased MAPK-phosphorylated Cx43 and cyclin E in explant tissues. We used peptide arrays to define a cyclin E-Cx43 binding region and generated CycliCx, a stearate-linked Cx43 phospho-mimetic peptide. In human coronary artery SMC, CycliCx inhibits platelet-derived growth factor-BB (PDGF-{beta})-induced changes in Cx43 trafficking and interactions with cyclin E, and stimulation of proliferation. RNAseq analysis identified CycliCx significantly inhibits PDGF-{beta}-induced proliferative pathways in SMC by limiting PDGF-{beta}-induced early G1/S phase cell cycle progression transcripts. Finally, we show CycliCx limits neointima formation in mice in vivo and in ex vivo human saphenous vein explants. Our data provide strong evidence for selective targeting of Cx43 as a viable therapeutic strategy for preventing neointimal formation in humans.

physiology↗

bioRxiv2025

Injury Induced Connexin 43 Expression Regulates Endothelial Wound Healing

Endothelial cell (EC) injury is a major contributing factor to vascular surgical failure. As such, understanding the mechanisms of endothelial healing is essential to the development of vascular therapeutics and procedures. Gap junctions formed by connexin 43 (Cx43) are implicated in regulating skin wound healing, but their role in endothelial healing is unknown. Secondary analysis of RNAseq data from in vivo injured mouse aortas (GEO: GSE115618), identified significant Cx43 upregulation in EC post-injury. We developed a novel in vivo model of EC injury using mouse carotid artery ligation to test the role of Cx43. We identified that EC immediately adjacent to the wound edge upregulate Cx43 protein expression, predominantly at cell-cell junctions. We show significantly delayed EC healing in a mouse model of inducible EC-specific Cx43 deletion (EC-Cx43 KO) at 24 hr post ligation. Single cell RNAseq analysis of 10,829 cells from 18 hr injured EC-WT and EC-Cx43 KO carotids revealed a Cx43-associated reduction in enrichment of EC pathways associated with migration, proliferation, and ERK/MAPK signaling pathways. Finally, the importance of Cx43 phosphorylation on EC healing was tested in mice with single-point alanine mutations (phospho-null) in known phosphorylation sites that alter Cx43 channel assembly and opening. Mice containing alanine mutations at ERK phosphorylated Cx43 serines (Cx43S255/262/279/282A) reduces healing rates similar to EC-Cx43 KO. These data suggest that EC injury-induced Cx43 upregulation, and subsequent Cx43 gap junction-mediated cell-to-cell communication are required for normal EC migration during wound healing after vascular injury. New and NoteworthyThese findings demonstrate for the first time that mechanical injury to large artery endothelium induces the expression of gap junction protein Cx43. This upregulation improves migratory and proliferative capacity of endothelial cells at the wound edge, facilitating timely wound closure. This phenomenon is dependent on appropriate gap junction function and turnover.

physiology↗

bioRxiv2024

Adipose tissue protein kinase D (PKD): regulation of signalling networks and its sex-dependent effects on metabolism

The protein kinase D (PKD) family of three highly homologous isoforms (PKD1, PKD2, and PKD3) are implicated as nutrient sensing signalling kinases that regulate the response of adipose and other tissues to the nutrient environment. However, the physiological role of adipose tissue PKD and its downstream cellular signalling targets are not well characterised. Phosphoproteomics was performed to elucidate signalling events downstream of PKD activation in differentiated 3T3L1 adipocytes using a triple isoform siRNA knockdown model. This revealed PKD-regulated pathways including insulin and cAMP signalling, which control metabolic responses in adipose tissue. An adipose tissue-specific and inducible dominant negative PKD (atDNPKD) mouse model that achieves functional inhibition of all three PKD isoforms was generated to assess the function of adipose PKD on whole-body metabolism in vivo in both male and female mice. Insulin-stimulated suppression of lipolysis was blunted in male, but not female, atDNPKD mice compared to control mice. Female, but not male, atDNPKD mice had higher fasting insulin but normal insulin action. Male atDNPKD mice showed greater sensitivity to the {beta}3-adrenergic receptor agonist CL316,243 on measures of lipolysis and energy expenditure, and displayed greater fat oxidation during fasting. During refeeding, male atDNPKD mice consumed less food and took longer to regain body weight lost during fasting. These effects were not observed in female mice. These findings indicate that PKD provides sex-dependent fine-tuning control of cAMP signalling in adipose tissue that is important for the coordination of energy balance during fasting and refeeding. NEW & NOTEWORTHYThe protein kinase D (PKD) family is a target for the treatment of obesity-related disorders. However, the physiological role of PKD in adipose tissue remains to be resolved. Using phosphoproteomics and an adipose tissue PKD loss-of-function mouse model, results demonstrate that PKD provides fine tuning of metabolic signalling in adipose tissue and metabolic responses to fasting and refeeding challenges, via coordination of feeding behaviour and regulation of body weight.

physiology↗

bioRxiv2023

Preserving endothelial integrity in human saphenous veins during preparation for coronary bypass surgery

ObjectiveWhile multiple factors influence coronary artery bypass graft success rates, preserving saphenous vein endothelium during surgery may improve patency. Standard methods of saphenous vein graft preparation in heparinized saline (saline) solutions result in endothelial loss and damage. Here we investigated the impact of preparing saphenous graft vessels in heparinized patient blood (blood) vs saline on cellular health and survival. MethodsSaphenous vein tissues from a total of 23 patients undergoing coronary artery bypass graft surgery were split into 2 treatment groups, 1) standard preparation using saline and 2) preparation using blood. Immediately following surgery, excess tissue was fixed for analysis. Level of endothelial coverage, oxidative stress marker 4-hydroxynonenal (4HNE), and oxidative stress protective marker nuclear factor erythroid 2-related factor 2 (NRF2) expression were evaluated. ResultsIn saline patient veins, histological analysis revealed a broken or absent luminal layer, suggesting a loss of endothelial cell (EC) coverage. Luminal cell coverage was notably preserved in blood-treated samples. Immunofluorescent staining of endothelial markers vascular endothelial cadherin (VE-cadherin) and endothelial nitric oxide (eNOS) identified a significant improvement in endothelial coverage in the blood group compared to saline. Although in both treatment groups EC expressed 4HNE indicating a similar level of oxidative stress, EC stored in blood solutions expressed higher levels of the protective transcription NRF2. ConclusionsOur data indicate that maintaining and preparing saphenous vein tissues in solutions containing heparinized blood helps preserve the endothelium and promotes vein graft health. This has the potential to improve long-term outcomes in patients. Central MessageDuring coronary artery bypass grafting, preparation of saphenous veins with heparinized saline damages the endothelium and increases oxidative stress. Heparinized blood preparation limits this endothelial loss and damage. Perspectives StatementSaphenous vein grafts are prone to failure through neointimal hyperplasia or thrombosis. Endothelial damage and loss are thought to be major contributing factors to graft failure. Here we find that preparation and preservation of saphenous vein grafts with patients own heparinized blood is sufficient to ensure endothelial preservation and protect vessels from oxidative stress compared with heparinized saline. These changes may increase long-term graft patency rates.

physiology↗

bioRxiv2022

Amyloid beta 42 alters cardiac metabolism and impairs cardiac function in obesity

There are epidemiological associations between obesity and type 2 diabetes, cardiovascular disease and Alzheimers disease. While some common aetiological mechanisms are known, the role of amyloid beta 42 (A{beta}42) in these diverse chronic diseases is obscure. Here we show that adipose tissue releases A{beta}42, which is increased from adipose tissue of obese mice and is associated with higher plasma A{beta}42. Increasing circulating A{beta}42 levels in non-obese mice had no effect on systemic glucose homeostasis but had obesity-like effects on the heart, including reduced cardiac glucose clearance and impaired cardiac function. These effects on cardiac function were not observed when circulating levels of the closely related A{beta}40 isoform were increased. Administration of an A{beta} neutralising antibody prevented obesity-induced cardiac dysfunction and hypertrophy. Furthermore, A{beta} neutralising antibody administration in established obesity prevented further deterioration of cardiac function. Multi-contrast transcriptomic analyses revealed that A{beta}42 impacted pathways of mitochondrial metabolism and exposure of cardiomyocytes to A{beta}42 inhibited mitochondrial function. These data reveal a role for systemic A{beta}42 in the development of cardiac disease in obesity and suggest that therapeutics designed for Alzheimers disease could be effective in combating obesity-induced heart failure.

physiology↗