Project description:ELTD1/ADGRL4 is an adhesion GPCR with an important role in angiogenesis. We recently identified a role for ELTD1 in wound repair and inflammation. Activation of ELTD1 in endothelial cells results in a type II EMT to myofibroblast-like cells that have enhanced angiogenic ability. Furthermore, expression of Eltd1 in murine breast cancer cells increases tumour growth by increasing blood vessel size and perfusion and by creating an immunosuppressive microenvironment. We thereforeAs extracellular vesicles (EVs) are known to be involved in vascular development, growth and maturation we investigated the composition and functional effects of the extracellular vesicles (EVs) isolated from ELTD1 expressexpressing cells to elucidate their role in these processes. A highly glycosylated form of the extracellular domain of ELTD1 is readily incorporated into EVs. Using mass spectrometry-based proteomics we identified proteins that are enriched in ELTD1-EVs and are involved in haemostasis and immune responses. ELTD1 enriched EVs were pro-angiogenic in vivo and in vitro and the presence of the extracellular domain alone induced endothelial sprouting. In endothelial cells experiencing laminar flow, ELTD1 levels were reduced in the EVs when compared to quiescent cells, showing a relationship between ELTD1 and the activation state of the endothelium. Using FACS, we detected a significant increase in vesicular ELTD1 in the plasma of patients with preeclampsia, a condition characterized by endothelial dysfunction. These data confirm a role for ELTD1 in wound repair and inflammation and reveal its potential as a biomarker of vessel dysfunction.
Project description:Myofibroblast activation is a cellular response elicited by a variety of physiological or pathological insults whereby cells initiate a coordinated response intended to eradicate the insult and then revert back to a basal state. However, an underlying theme in various disease states is persistent myofibroblast activation that fails to resolve. Based on multiple observations, we hypothesized that the secreted factors harvested from co-culturing amniotic stem cells might mimic the anti-inflammatory state that cell-free amniotic fluid (AF) elicits. We optimized an amnion epithelial and amniotic fluid cell co-culture system, and tested this hypothesis in the context of myofibroblast activation. However, we discovered that co-cultured amniotic cell conditioned media (coACCM) and AF have opposing effects on myofibroblast activation: coACCM activates the epithelial-mesenchymal transition (EMT) and stimulates gene expression patterns associated with myofibroblast activation, while AF does the opposite. Intriguingly, purified extracellular vesicles (EVs) from AF are necessary and sufficient to activate EMT and inflammatory gene expression patterns, while the EV-depleted AF potently represses these responses. In summary, these data indicate that coACCM stimulates myofibroblast activation, while AF represses it. We interpret these findings to suggest that coACCM, AF, and fractionated AF represent unique biologics that elicit differential cellular responses correlated with a wide variety of pathological states, and therefore could have broad utility in the clinic and the lab.
Project description:Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible, and lethal lung disease. The initiation of IPF involves microinjuries to and/or dysfunction of the alveolar epithelium, but factors that determine fibrosis progression or normal tissue repair are largely unknown. We previously demonstrated that autophagy inhibition-mediated epithelial-mesenchymal transition (EMT) in human alveolar epithelial type II (ATII) cells augments local myofibroblast differentiation in pulmonary fibrosis by paracrine signalling. Here, we report that liver kinase B1 (LKB1) inactivation in ATII cells induces autophagy inhibition and EMT as a consequence. In IPF lungs, this is caused by a downregulation of CAB39L, a key subunit within the LKB1 complex. 3D co-cultures of ATII cells and lung fibroblast MRC5 coupled with RNA sequencing (RNA-seq) confirmed that paracrine signalling between LKB1-depleted ATII cells and fibroblasts augmented myofibroblast differentiation. Together these data suggest that reduced autophagy caused by LKB1 inhibition can induce EMT in ATII cells and contribute to fibrosis via aberrant epithelial–fibroblast crosstalk.
Project description:Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible, and lethal lung disease. The initiation of IPF involves microinjuries to and/or dysfunction of the alveolar epithelium, but factors that determine fibrosis progression or normal tissue repair are largely unknown. We previously demonstrated that autophagy inhibition-mediated epithelial-mesenchymal transition (EMT) in human alveolar epithelial type II (ATII) cells augments local myofibroblast differentiation in pulmonary fibrosis by paracrine signalling. Here, we report that liver kinase B1 (LKB1) inactivation in ATII cells induces autophagy inhibition and EMT as a consequence. In IPF lungs, this is caused by a downregulation of CAB39L, a key subunit within the LKB1 complex. 3D co-cultures of ATII cells and lung fibroblast MRC5 coupled with RNA sequencing (RNA-seq) confirmed that paracrine signalling between LKB1-depleted ATII cells and fibroblasts augmented myofibroblast differentiation. Together these data suggest that reduced autophagy caused by LKB1 inhibition can induce EMT in ATII cells and contribute to fibrosis via aberrant epithelial–fibroblast crosstalk.
Project description:Transforming growth factor-β (TGFβ) is a key mediator of fibroblast activation in fibrotic diseases including systemic sclerosis. Here we show that Engrailed 1 (EN1) is re-expressed in multiple fibroblast subpopulations in the skin of SSc patients. We characterize EN1 as a molecular amplifier of TGFβ signaling in myofibroblast differentiation: TGFβ induces EN1 expression in a SMAD3-dependent manner, and, in turn, EN1 mediates the pro-fibrotic effects of TGFβ. RNA sequencing demonstrates that EN1 induces a pro-fibrotic gene expression profile functionally related to the cytoskeleton organization and ROCK activation. EN1 regulates gene expression by modulating the activity of SP1 and other SP-transcription factors, as confirmed by ChIP-seq experiments for EN1 and SP1. Functional experiments confirm the coordinating role of EN1 on ROCK activity and the re-organization of cytoskeleton during myofibroblast differentiation both in standard fibroblast culture systems and in in vitro skin models. Consistently, mice with fibroblast-specific knockout of En1 demonstrate impaired fibroblast-to-myofibroblast transition and are partially protected from experimental skin fibrosis.
Project description:Transforming growth factor-β (TGFβ) is a key mediator of fibroblast activation in fibrotic diseases including systemic sclerosis. Here we show that Engrailed 1 (EN1) is re-expressed in multiple fibroblast subpopulations in the skin of SSc patients. We characterize EN1 as a molecular amplifier of TGFβ signaling in myofibroblast differentiation: TGFβ induces EN1 expression in a SMAD3-dependent manner, and, in turn, EN1 mediates the pro-fibrotic effects of TGFβ. RNA sequencing demonstrates that EN1 induces a pro-fibrotic gene expression profile functionally related to the cytoskeleton organization and ROCK activation. EN1 regulates gene expression by modulating the activity of SP1 and other SP-transcription factors, as confirmed by ChIP-seq experiments for EN1 and SP1. Functional experiments confirm the coordinating role of EN1 on ROCK activity and the re-organization of cytoskeleton during myofibroblast differentiation both in standard fibroblast culture systems and in in vitro skin models. Consistently, mice with fibroblast-specific knockout of En1 demonstrate impaired fibroblast-to-myofibroblast transition and are partially protected from experimental skin fibrosis.
Project description:Sporadic venous malformations (VM) and angiomatosis of soft tissue (AST) are benign, congenital slow-flow vascular anomalies that have no available targeted therapies. Depending on the size and location of the lesion, symptoms vary from motility disturbances to pain and disfigurement. In this work, we analyzed tissue samples from 36 patients with VM or AST. Additionally, patient-derived endothelialCD31+ and intervascular stromalCD31-, vimentin+ cells were used. Majority of the samples had a somatic mutation in either TEK or PIK3CA gene. Activation of ErbB1/EGFR pathway and expression of a pro-angiogenic ligand, transforming growth factor A, was found in both VM and AST samples. Activation of EGFR pathway led to the secretion of a major angiogenic factor VEGF-A. Intriguingly, patient-derived intervascular stromal cells were able to induce angiogenesis of genotypically normal endothelial cells via paracrine signaling. Significant decrease in endothelial sprouting and VEGF-A production were observed after treatment with a pan-ErbB inhibitor afatinib. To conclude, our data demonstrate that intervascular stromal cells play a role in the pathogenesis of AST and VM by producing pro-angiogenic factors that activate EGFR. Activation of EGFR pathway was not associated with a genetic cause but is likely caused by hypoxia. EGFR targeted therapy of both intervascular stromal cells and endothelial cells could be beneficial for the treatment of a subpopulation of AST and VM lesions expressing EGFR ligands.
Project description:Epithelial-to-Mesenchymal Transition (EMT) is a key process contributing to the aggressiveness of cancer cells. EMT is triggered by activation of different transcription factors collectively known as EMT-TFs. Different cellular cues and cell signalling networks activate EMT at transcriptional and posttranscriptional level in different biological and pathological situations. Among them, overexpression of LOXL2 (lysyl oxidase-like 2) induces EMT independent of its catalytic activity. Remarkably, perinuclear/cytoplasmic accumulation of LOXL2 is a poor prognosis marker of squamous cell carcinomas and is associated to basal breast cancer metastasis by mechanisms no yet fully understood. Here, we report that overexpression of LOXL2 promotes its accumulation in the Endoplasmic Reticulum where it interacts with HSPA5 leading to activation of the IRE1-XBP1-branch of the Unfolded Protein Response (UPR). LOXL2-dependent UPR activation induces the expression of several EMT-TFs: SNAI1, SNAI2, ZEB2 and TCF3 that are direct transcriptional targets of XBP1. Remarkably, inhibition of IRE1 blocks LOXL2-dependent upregulation of EMT-TFs thus hindering EMT induction. LOXL2 relationship to Endoplasmic Reticulum Stress
Project description:Rationale. Obesity is a risk factor for atherothrombosis and various cancers. However, the mechanisms are not completely uncovered. Objectives. We aimed to verify whether the microparticles (MPs) released from thrombin-activated platelets differed in obese and nonobese women for number, size, and proteomics cargo and the capacity to modulate in vitro the expression of genes related to the epithelial to mesenchymal transition (EMT) and the endothelial to mesenchymal transition (EndMT), and COX-2, a pro-angiogenic pathway. Methods and Results. MPs were obtained from thrombin activated platelets of four obese women and their matched, lean controls . MPs were analyzed by cytofluorimeter and protein content by liquid chromatography-mass spectrometry. Obese MPs were not different in number but were characterized by increased heterogeneity in size. In obese individuals, MPs containing mitochondria (mitoMPs) expressed lower CD41 levels and increased phosphatidylserine associated with enhanced Factor V representing a signature of a prothrombotic state. Proteomics analysis identified 44 proteins downregulated and 3 upregulated in obese versus nonobese MPs . A reduction in the proteins involved in mitophagy and antioxidant defenses, and of the -granular membrane was detected in the MPs of obese individuals. MPs released from platelets of obese individuals were more prone to induce the expression of marker genes of EMT and EndMT when incubated with HT29 cells and human cardiac microvascular endothelial cells(HCMEC), respectively. A protein, highly enhanced in obese MPs, was the pro-platelet basic protein with pro-inflammatory and tumorigenic actions. MPs from obese, but not nonobese, women induced COX-2 in HCMEC. Conclusions. Platelet-derived MPs of obese women showed higher heterogeneity in size and contained different levels of proteins relevant to thrombosis and tumorigenesis. Obese MPs presented enhanced capacity to induce changes in the expression of EMT and EndMT markers and COX-2. These effects might contribute to the increased risk for the development of thrombosis and multiple malignancies in obesity.
Project description:The durability of interferon signaling in human aortic endothelial activation was tested. Pro-adhesive and costimulatory gene expression, phenotype, secretome and JAK/STAT phosphorylation in human primary endothelial cells were measured under chronic and transient IFNγ stimulation, with various JAK inhibitors.