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

Hypertension and increased endothelial mechanical stretch promote monocyte differentiation and activation: roles of STAT3, interleukin 6 and hydrogen peroxide

Aims: Monocytes play an important role in hypertension. Circulating monocytes in humans exist as classical, intermediate and non-classical forms. Monocyte differentiation can be influenced by the endothelium, which in turn is activated in hypertension by mechanical stretch. We sought to examine the role of increased endothelial stretch and hypertension on monocyte phenotype and function. Methods and Results: Human monocytes were cultured with confluent human aortic endothelial cells undergoing either 5% or 10% cyclical stretch. We also characterized circulating monocytes in normotensive and hypertensive humans. In addition, we quantified accumulation of activated monocytes and monocyte-derived cells in aortas and kidneys of mice with Angiotensin II-induced hypertension. Increased endothelial stretch enhanced monocyte conversion to CD14++CD16+ intermediate monocytes and monocytes bearing the CD209 marker and markedly stimulated monocyte mRNA expression of interleukin (IL)-6, IL-1β, IL-23, chemokine (C-C motif) ligand 4 and tumor necrosis factor α. STAT3 in monocytes was activated by increased endothelial stretch. Inhibition of STAT3, neutralization of IL-6 and scavenging of hydrogen peroxide prevented formation of intermediate monocytes in response to increased endothelial stretch. We also found evidence that nitric oxide inhibits formation of intermediate monocytes and STAT3 activation. In vivo studies demonstrated that humans with hypertension have increased intermediate and non-classical monocytes and that intermediate monocytes demonstrate evidence of STAT3 activation. Mice with experimental hypertension exhibit increased aortic and renal infiltration of monocytes, dendritic cells and macrophages with activated STAT3. Conclusions: These findings provide insight into how monocytes are activated by the vascular endothelium during hypertension. This is likely in part due to a loss of nitric oxide signaling and increased release of IL-6 and hydrogen peroxide by the dysfunctional endothelium and a parallel increase in STAT activation in adjacent monocytes. Interventions to enhance bioavailable nitric oxide, reduce IL-6 or hydrogen peroxide production or to inhibit STAT3 may have anti-inflammatory roles in hypertension and related conditions

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

Cre transgene results in global attenuation of the cAMP/PKA pathway.

Use of the cre transgene in in vivo mouse models to delete a specific 'floxed' allele is a well-accepted method for studying the effects of spatially or temporarily regulated genes. During the course of our investigation into the effect of cyclic adenosine 3',5'-monophosphate-dependent protein kinase A (PKA) expression on cell death, we found that cre expression either in cultured cell lines or in transgenic mice results in global changes in PKA target phosphorylation. This consequently alters gene expression profile and changes in cytokine secretion such as IL-6. These effects are dependent on its recombinase activity and can be attributed to the upregulation of specific inhibitors of PKA (PKI). These results may explain the cytotoxicity often associated with cre expression in many transgenic animals and may also explain many of the phenotypes observed in the context of Cre-mediated gene deletion. Our results may therefore influence the interpretation of data generated using the conventional cre transgenic system

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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

Role of p53 in cAMP/PKA pathway mediated apoptosis

Deregulated β-adrenoceptor/cAMP-PKA pathway is implicated in a range of human diseases, such as neuronal loss during aging, cardiomyopathy and septic shock. The molecular mechanism of this process is, however, only poorly understood. We recently had demonstrated that the β-adrenoceptor/cAMP-PKA pathway triggers apoptosis through the transcriptional induction of the pro-apoptotic BH3-only Bcl-2 family member BIM in tissues, such as the thymus and the heart. Induction of BIM is driven by the transcriptional co-activator CBP (CREB Binding Protein) together with the proto-oncogene c-Myc. Association of CBP with c-Myc leads to altered histone acetylation and methylation pattern at the BIM promoter site [Lee et al., Cell Death Difference 20(7):941-952 (2013)]. However since CBP is a co-factor for multiple transcription factors, BH-3 only proteins other than Bim could also contribute to this apoptosis pathway. Here we provide evidence for the involvement of p53-CBP axis in apoptosis through Puma/Noxa induction, in response to β-adrenoceptor activation. Our findings highlight the molecular complexity of pathophysiology associated with a deregulated neuro-endocrine system and for developing novel therapeutic strategies for these diseases

Inhibition of cathepsin proteases attenuates migration and sensitizes aggressive N-Myc amplified human neuroblastoma cells to doxorubicin

Neuroblastoma arises from the sympathetic nervous system and accounts for 15% of childhood cancer mortality. Amplification of the oncogene N-Myc is reported to occur in more than 20% of patients. While N-Myc amplification status strongly correlates with higher tumour aggression and resistance to treatment, the role of N-Myc in the aggressive progression of the disease is poorly understood. N-Myc being a transcription factor can modulate the secretion of key proteins that may play a pivotal role in tumorigenesis. Characterising the soluble secreted proteins or secretome will aid in understanding their role in the tumour microenvironment, such as promoting cancer cell invasion and resistance to treatment. The aim of this study is to characterise the secretome of human malignant neuroblastoma SK-N-BE2 (N-Myc amplified, more aggressive) and SH-SY5Y (N-Myc non-amplified, less aggressive) cells. Conditioned media from SK-N-BE2 and SH-SY5Y cell lines were subjected to proteomics analysis. We report a catalogue of 894 proteins identified in the secretome isolated from the two neuroblastoma cell lines, SK-N-BE2 and SH-SY5Y. Functional enrichment analysis using FunRich software identified enhanced secretion of proteins implicated in cysteine peptidase activity in the aggressive N-Myc amplified SK-N-BE2 secretome compared to the less tumorigenic SH-SY5Y cells. Protein-protein interaction-based network analysis highlighted the enrichment of cathepsin and epithelial-to-mesenchymal transition sub-networks. For the first time, inhibition of cathepsins by inhibitors sensitized the resistant SK-N-BE2 cells to doxorubicin as well as decreased its migratory potential. The dataset of secretome proteins of N-Myc amplified (more aggressive) and non-amplified (less aggressive) neuroblastoma cells represent the first inventory of neuroblastoma secretome. The study also highlights the prominent role of cathepsins in the N-Myc amplified neuroblastoma pathogenesis. As N-Myc amplification correlates with aggressive neuroblastoma and chemotherapy-based treatment failure, co-treatment with cathepsin inhibitors might be a better avenue for disease management