Extracellular vesicles secreted by Saccharomyces cerevisiae are involved in cell wall remodelling

Extracellular vesicles (EVs) are membranous vesicles that are released by cells. In this study, the role of the Endosomal Sorting Complex Required for Transport (ESCRT) machinery in the biogenesis of yeast EVs was examined. Knockout of components of the ESCRT machinery altered the morphology and size of EVs as well as decreased the abundance of EVs. In contrast, strains with deletions in cell wall biosynthesis genes, produced more EVs than wildtype. Proteomic analysis highlighted the depletion of ESCRT components and enrichment of cell wall remodelling enzymes, glucan synthase subunit Fks1 and chitin synthase Chs3, in yeast EVs. Interestingly, EVs containing Fks1 and Chs3 rescued the yeast cells from antifungal molecules. However, EVs from fks1∆ or chs3∆ or the vps23∆chs3∆ double knockout strain were unable to rescue the yeast cells as compared to vps23∆ EVs. Overall, we have identified a potential role for yeast EVs in cell wall remodelling.Kening Zhao, Mark Bleackley, David Chisanga, Lahiru Gangoda, Pamali Fonseka, Michael Liem, Hina Kalra, Haidar Al Saffar, Shivakumar Keerthikumar, Ching-Seng Ang, Christopher G. Adda, Lanzhou Jiang, Kuok Yap, Ivan K. Poon, Peter Lock, Vincent Bulone, Marilyn Anderson, Suresh Mathivana

Oral administration of bovine milk-derived extracellular vesicles induces senescence in the primary tumor but accelerates cancer metastasis

The concept that extracellular vesicles (EVs) from the diet can be absorbed by the intestinal tract of the consuming organism, be bioavailable in various organs, and in-turn exert phenotypic changes is highly debatable. Here, we isolate EVs from both raw and commercial bovine milk and characterize them by electron microscopy, nanoparticle tracking analysis, western blotting, quantitative proteomics and small RNA sequencing analysis. Orally administered bovine milk-derived EVs survive the harsh degrading conditions of the gut, in mice, and is subsequently detected in multiple organs. Milk-derived EVs orally administered to mice implanted with colorectal and breast cancer cells reduce the primary tumor burden. Intriguingly, despite the reduction in primary tumor growth, milk-derived EVs accelerate metastasis in breast and pancreatic cancer mouse models. Proteomic and biochemical analysis reveal the induction of senescence and epithelial-to-mesenchymal transition in cancer cells upon treatment with milk-derived EVs. Timing of EV administration is critical as oral administration after resection of the primary tumor reverses the pro-metastatic effects of milk-derived EVs in breast cancer models. Taken together, our study provides context-based and opposing roles of milk-derived EVs as metastasis inducers and suppressors

High blood pressure and cyclic stretch after cerebral amyloid deposition and endothelial function

Theoretical thesis.Bibliography: leaves 50-61.1. Introduction -- 2. Material and methods -- 3. Results -- 4. Discussion -- 5. Summary and conclusions.Background: Amyloid β (Aβ) deposition is a hallmark of Alzheimer’s disease (AD). Increased pulsatility, endothelial dysfunction (ED) and inflammation, indicators of vascular stiffness, are associated with AD. Additionally, vascular stiffness is linked to hypertension, a risk factor for AD. Aim: This study aimed to determine effects of high blood pressure (BP) on cerebral Aβ deposition in rodent models, spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY) and investigate effects of cyclic stretch (CS) on expression of amyloid precursor protein (APP), endothelial nitric oxide synthase (eNOS) and intercellular cell adhesion molecule-1 (ICAM-1) in human cerebral microvascular endothelial cells (hCMEC). Methods: Hippocampal (HC) and frontal cortex (FC) regions of SHR and WKY rats were analysed using western blotting to determine effect of BP on cerebral Aβ deposition. hCMEC were subjected to 5%, 10% or 20 % CS compared to control (0% CS) to evaluate pulsatility, ED and inflammation using western blotting and/or RTqPCR. Results: Aβ oligomerisation increased in SHR compared to WKY in HC (P<0.01) and FC (P<0.001). APP mRNA expression increased at 5%, decreased at 20% CS; eNOS decreased at both (P<0.0001). APP and ICAM-1 protein expression dose-dependently increased at 5% and 10% CS (P<0.01) and decreased at 20% CS. eNOS protein levels decreased at all CS (P<0.0001). Conclusions: Results suggest that high BP and CS respectively alter the processing and expression of cerebral APP. Prolonged CS may induce ED by increasing ICAM-1, thereby mitigating eNOS expression. Findings mechanistically support the association of elevated pulsatility and arterial stiffness with AD.Mode of access: World wide web1 online resource (xi, 61 leaves illustrations (some colour

Pulsatile stretch alters expression and processing of amyloid precursor protein in human cerebral endothelial cells

Objective: Amyloid β (Aβ) deposition is a hallmark of Alzheimer's disease (AD). Aβ is generated via enzymatic cleavage of amyloid precursor protein (APP). Increased APP expression is associated with elevated amyloid burden. Elevated pulsatility of arterial pressure, as a vascular factor indicative of vascular stiffness, is associated with AD. This study investigates whether increased magnitude of pulsatile stretch of human cerebral microvascular endothelial cells (hCMEC) alters expression and processing of APP. Design and method: hCMECs were cultured on flexible silicone chambers and subjected to 5%, 10% or 15% cyclic stretch (ShellPA stretch system, Menicon Life Science) for 18 hours at 1 Hz (n = 5-11 for each stretch magnitude). Comparison was made with controls (0% stretch) to evaluate the effect of pulsatility on APP. APP expression was quantified using western blots with glyceraldehyde 3-phosphate dehydrogenase as the loading control. APP processing was evaluated in the cell culture supernatants by ELISA for secreted Aβ42. Results were analyzed using one way ANOVA (mean ± SEM, %control) or Pearson correlation. Results: The densitometric analysis (expressed as a percentage of control values) of protein expression of APP showed that it was significantly higher at 10% of cyclic stretch (160.9 ± 21%) compared to both the static control (100%, p < 0.05) and 5% cyclic stretch magnitude (107.8 ± 12%, p < 0.05). The APP protein expression at 15% stretch magnitude (138.3 ± 12%) was slightly, but not significantly higher than the static control and 5% cyclic stretch. There was a significant correlation between the % stretch magnitude and secretion of A b42 (r² = 0.4132, p < 0.0001). Conclusions: Increasing cyclic stretch of cerebral vascular ECs altered the expression of APP and the secretion of A b42. Prolonged cyclic stretch may induce APP expression and A b formation. Findings mechanistically support the association of elevated haemodynamic pulsatility and arterial stiffness with AD.1 page(s

High blood pressure and cyclic stretch alter cerebral amyloid deposition and endothelial function

Background: Amyloid β (Aβ) deposition is a hallmark of Alzheimer's disease (AD). Increased pulsatility, endothelial dysfunction (ED) and inflammation, as indicators of vascular stiffness, are associated with (AD). Additionally, vascular stiffness is linked to hypertension, a risk factor for AD. Aim: To determine effects of high blood pressure (BP) on cerebral Aβ deposition in the spontaneously hypertensive rat (SHR) and normotensive Wistar Kyoto (WKY) rat, and investigate effects of pulsatile cyclic stretch (CS) on expression of amyloid precursor protein (APP), endothelial nitric oxide synthase (eNOS) and intercellular cell adhesion molecule-1 (ICAM-1) in human cerebral microvascular endothelial cells. Methods: Hippocampal (HC) and frontal cortex (FC) regions of SHR and WKY rats were analysed using western blotting (WB) to determine effects of BP on cerebral Aβ deposition. hCMEC were subjected to 5%, 10% or 20% CS compared to control (0% CS) to evaluate pulsatility, ED and inflammation using WB and/or quantitative RT-PCR. Results: Aβ oligomerization was increased in SHR compared to WKY in HC (P<0.01) and FC (P<0.001). APP mRNA level was increased at 5%, was decreased at 20%, while eNOS was decreased at both (P<0.0001). APP and ICAM-1 protein levels were dose-dependently increased at 5% and 10% CS (P<0.01) and decreased at 20% CS. eNOS protein levels were decreased at all CS (P<0.0001). Conclusions: Our results suggest that high BP and CS, respectively, alter the processing and expression of cerebral APP. Prolonged CS may induce ED by increasing ICAM-1, thereby mitigating eNOS expression. Findings mechanistically support the association of elevated pulsatility and arterial stiffness with AD.1 page(s

Ethanol impairs expression of estrogen receptors and increases ICAM-1 and galectin-3 in human umbilical vein and cerebral microvascular endothelial cells

Background: Endothelial cells play a pivotal role in maintaining vascular homeostasis and endothelial dysfunction (ED) is an underlying mechanism of cardiovascular disease. Estrogen deficiency is one of the causes of ED that precedes the changes in vasomotor tone, inflammation and arterial stiffness, leading to vascular structural changes and increased blood pressure. Aim: To determine the effects of ethanol (EtOH) on the expression of estrogen receptors (ERs) and inflammatory markers (ICAM-1, galectin-3) using two different types of endothelial cells: human umbilical vein (HUVEC), as a model of large vessel endothelial cells, and cerebral microvascular endothelial cells (hCMEC), which are associated with the blood-brain barrier. Methods: Cells were treated with EtOH and ED and were then evaluated for the expression of ERs (ERα, ERβ, G protein coupled ER (GpER)), as well as for the regulation of ICAM-1, galectin-3, and the phosphorylation of IκBα using Western blot assay. Results: Exposure to EtOH decreased the expression of ERα and GpER, but did not change ERβ (ERα was not detected in the HUVEC line used in this study). In terms of inflammatory factors, EtOH increased ICAM-1 and galectin-3 in both cell lines and activated p-IκBα in hCMEC. Conclusions: These findings suggest that alcohol accelerates ED by decreasing estrogenic effects and increasing inflammatory response in both the systemic and cerebral vasculature.1 page(s

Pulsatile stretch as a novel modulator of amyloid precursor protein processing and associated inflammatory markers in human cerebral endothelial cells

Abstract Amyloid β (Aβ) deposition is a hallmark of Alzheimer’s disease (AD). Vascular modifications, including altered brain endothelial cell function and structural viability of the blood-brain barrier due to vascular pulsatility, are implicated in AD pathology. Pulsatility of phenomena in the cerebral vasculature are often not considered in in vitro models of the blood-brain barrier. We demonstrate, for the first time, that pulsatile stretch of brain vascular endothelial cells modulates amyloid precursor protein (APP) expression and the APP processing enzyme, β-secretase 1, eventuating increased-Aβ generation and secretion. Concurrent modulation of intercellular adhesion molecule 1 and endothelial nitric oxide synthase (eNOS) signaling (expression and phosphorylation of eNOS) in response to pulsatile stretch indicates parallel activation of endothelial inflammatory pathways. These findings mechanistically support vascular pulsatility contributing towards cerebral Aβ levels

One protein, multiple pathologies: multifaceted involvement of amyloid β in neurodegenerative disorders of the brain and retina

© 2016, Springer International Publishing. Accumulation of amyloid β (Aβ) and its aggregates in the ageing central nervous system is regarded synonymous to Alzheimer’s disease (AD) pathology. Despite unquestionable advances in mechanistic and diagnostic aspects of the disease understanding, the primary cause of Aβ accumulation as well as its in vivo roles remains elusive; nonetheless, the majority of the efforts to address pathological mechanisms for therapeutic development are focused towards moderating Aβ accumulation in the brain. More recently, Aβ deposition has been identified in the eye and is linked with distinct age-related diseases including age-related macular degeneration, glaucoma as well as AD. Awareness of the Aβ accumulation in these markedly different degenerative disorders has led to an increasing body of work exploring overlapping mechanisms, a prospective biomarker role for Aβ and the potential to use retina as a model for brain related neurodegenerative disorders. Here, we present an integrated view of current understanding of the retinal Aβ deposition discussing the accumulation mechanisms, anticipated impacts and outlining ameliorative approaches that can be extrapolated to the retina for potential therapeutic benefits. Further longitudinal investigations in humans and animal models will determine retinal Aβ association as a potential pathognomonic, diagnostic or prognostic biomarker