Project description:Multiple signaling pathways, structural proteins and transcription factors are involved in regulation of endothelial barrier function. The Forkhead protein FOXF1 is a key transcriptional regulator of lung embryonic development, and we use a conditional knockout approach to examine the role of FOXF1 in adult lung homeostasis and lung injury and repair. Tamoxifen-regulated deletion of both Foxf1 alleles in endothelial cells of adult mice (Pdgfb-iCreER/Foxf1 caused lung inflammation and edema, leading to respiratory insuffency and uniform mortality. Deletion of a single foxf1 allele was sufficient to increase susceptibility of heterozygous mice to acute lung injury. FOXF1 abundance was decreased in pulmonary endothelial cells of human patients with acute lung injury. Gene expression analysis of pulmonary endothelial cells of FOXF1 deletion indicated reduced expression for genes critical for maintance and regulation of adherens junctions. FOXF1 knockdown in vitro and in vivo disrupted adherens junctions, increased lung endothelial permeability, and the abundance of mRNA and protein for sphingosine 1 phosphate receptor 1 (S1PR1), a key regulator of endothelial barrier function. Chromatin immunoprecipitation and luciferase reporter assay demonstrated that FOXF1 directly bound to and induced the tanscriptional activity of the S1pr1 promoter. Pharmacological administratiion of S1P to injured pdgfb-iCreER/Foxf1 mice restored endothelial barrier function, decreased lung edema and improved survival. Thus, FOXF1 promotes normal lung homeostasis and lung repair, at least in part, by enhancing endothelial barrier function through transcriptional activation of the S1P/S1PR1/ signaling pathway.
Project description:Increased endothelial permeability and failure to repair is the hallmark of several vascular diseases including acute lung injury (ALI). However, little is known about the intrinsic pathways that activate endothelial cell (EC) regenerative programs and thereby tissue repair. Studies have invoked a crucial role of sphingosine-1-phosphate (S1P) in resolving endothelial hyperpermeability through activation of the G-protein coupled receptor, sphingosine-1-phosphate receptor 1 (S1PR1). Here, we addressed mechanisms of generation of S1PR1+ EC, which may prevent endothelial injury. Studies were made using inducible EC-S1PR1-/- (iEC-S1PR1-/-) mice and S1PR1-GFP reporter mice to trace the generation of S1PR1+ EC. We observed in a mouse model of endotoxemia that S1P generation induced the programming of S1PR1lo to S1PR1+ EC, which comprised 80% of lung EC. The transition of these cells was required for reestablishing the endothelial barrier. We also observed that conditional deletion of S1PR1 in EC increased vascular permeability. RNA-seq analysis of S1PR1+ EC showed enrichment of genes regulating S1P synthesis and transport, sphingosine kinase 1 (SPHK1) and SPNS2, respectively. The activation of transcription factors EGR1 and STAT3 were essential for transcribing SPHK1 and SPNS2, respectively, to increase S1P production that served to amplify S1PR1+ EC transition. Transplantation of S1PR1+ EC into injured lung vasculature restored endothelial integrity. Our findings show that generation of a S1PR1+ EC population activates the endothelial regenerative program mediating vascular endothelial repair, thus raising the possibility of harnessing this pathway to restore vascular homeostasis in inflammatory injury.
Project description:Cancer cells re-program normal lung endothelial cells (EC) into tumor-associated endothelial cells (TEC) that form leaky vessels supporting carcinogenesis. Transcriptional regulators that control reprogramming of EC into TEC are poorly understood. We identified Forkhead box F1 (FOXF1) as a critical regulator of EC-to-TEC transition. FOXF1 was highly expressed in normal lung vasculature but was decreased in TEC within non-small cell lung cancers (NSCLC). Low FOXF1 correlated with poor overall survival of NSCLC patients. In mice, endothelial-specific deletion of FOXF1 decreased pericyte coverage, increased vessel permeability and hypoxia, and promoted lung tumor growth and metastasis. Endothelial-specific over-expression of FOXF1 normalized tumor vessels and inhibited progression of lung cancer. FOXF1-deficiency decreased Wnt/β-catenin signaling in TECs through direct transcriptional activation of Fzd4. Restoring FZD4 expression in FOXF1-deficient TECs through endothelial-specific nanoparticle delivery of Fzd4 cDNA rescued Wnt/β-catenin signaling in TECs, normalized tumor vessels and inhibited progression of lung cancer. Altogether, FOXF1 increases tumor vessel stability, and inhibits lung cancer progression by stimulating FZD4/Wnt/β-catenin signaling in TECs. Nanoparticle delivery of FZD4 cDNA has a promise for future therapies in NSCLC.
Project description:FOXF1, a member of the forkhead box family of transcription factors, has been previously shown to be critical for lung development, homeostasis, and injury responses. However, the role of FOXF1 in lung regeneration is unknown. Herein, we performed partial pneumonectomy, a model of lung regeneration, in mice lacking one Foxf1 allele in endothelial cells (PDGFb-iCre/Foxf1fl/+ mice). Endothelial cell proliferation was significantly reduced in regenerating lungs from mice deficient for endothelial Foxf1. Decreased endothelial proliferation was associated with delayed lung regeneration as shown by reduced respiratory volume in Foxf1-deficient lungs. FACS-sorted endothelial cells isolated from regenerating PDGFb-iCre/Foxf1fl/+ and control lungs were used for RNAseq analysis to identify FOXF1 target genes. Foxf1 deficiency altered expression of numerous genes including those regulating extracellular matrix remodeling (Timp3, Adamts9) and cell cycle progression (Cdkn1a, Cdkn2b, Cenpj, Tubb4a), which are critical for lung regeneration. Deletion of Foxf1 increased Timp3 mRNA and protein, decreasing MMP14 activity in regenerating lungs. ChIPseq analysis for FOXF1 and histone methylation marks identified DNA regulatory regions with the Cd44, Cdkn1a, and Cdkn2b genes, indicating they are direct FOXF1 targets. Thus FOXF1 stimulates lung regeneration following partial pneumonectomy via direct transcriptional regulation of genes critical for extracellular matrix remodeling and cell cycle progression.
Project description:Mechanical forces generated through adhesive interaction of endothelial cells (EC) influence nuclear envelope and thereby gene transcription. Alteration in EC mechanical forces may trigger aberrant gene transcription leading to lethal vascular diseases including acute lung injury (ALI). The intrinsic pathways that instruct EC nuclear-mechanotransduction and thereby maintains vascular homeostasis remain elusive. We have identified focal adhesion kinase (FAK)-mediated mechanotransduction at the nuclear envelope in instructing transcription of EC-barrier protective genes. We show that loss of EC-FAK increases intracellular tension, which in turn activates nuclear envelop protein emerin, and DNA methyltransferase 3a (DNMT3a). Methylation of transcription factor KLF2 promoter by DNMT3a impaired KLF2 synthesis and transcription of the crucial barrier-maintaining gene, S1PR1. Restoring KLF2 or S1PR1 expression or impairing emerin or DNMT3a activity rescued vascular homeostasis in lungs with FAK-deficient or WT-damaged endothelium. Thus, FAK protects against tension-induced aberrant DNA methylation in EC and is a promising target to prevent ALI.
Project description:Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant accumulation of collagen-secreting myofibroblasts. Development of effective therapies is limited due to incomplete understanding of molecular mechanisms regulating myofibroblast expansion. FOXF1 transcription factor is expressed in resident lung fibroblasts, but its role in lung fibrosis remains unknown due to the lack of genetic mouse models. Through comprehensive analysis of human IPF genomics data, lung biopsies and transgenic mice with fibroblast-specific inactivation of FOXF1, the present study shows that FOXF1 inhibits pulmonary fibrosis. FOXF1 deletion increases myofibroblast invasion, collagen secretion, and promotes a switch from of N-cadherin (CDH2) to Cadherin-11 (CDH11), which is critical step in acquisition of pro-fibrotic phenotype. FOXF1 directly binds to Cdh2 and Cdh11 promoters and differentially regulates transcription of these genes. Re-expression of CDH2 or inhibition of CDH11 in FOXF1-deficient cells reduces myofibroblast invasion in vitro. FOXF1 inhibits pulmonary fibrosis by regulating a switch from CDH2 to CDH11 in lung myofibroblasts.
Project description:Lung transplantation remains the only viable therapy for patients with end-stage lung disease; however, full utilization of this treatment strategy is severely compromised by the lack of donor lung availability. For example, the vast majority of donor lungs available for transplantation are obtained from brain death (BD) individuals. Unfortunately, the autonomic storm which accompanies BD often results in neurogenic pulmonary edema (NPE), thereby either producing irreversible lung injury or leading to primary graft dysfunction following lung transplantation. We previously demonstrated that sphingosine 1-phosphate (S1P), a phospholipid angiogenic factor and major barrier-enhancing agent, as well as S1P analogues serve to reduce vascular permeability and ischemia/reperfusion (I/R) lung injury in rodents via ligation of the S1P1 receptor, S1PR1. As primary lung graft dysfunction is induced by lung vascular endothelial cell barrier dysfunction, we hypothesized that SEW-2871, a S1PR1 agonist, may attenuate NPE when administered to the donor shortly after BD. Significant lung injury was observed 4h after BD in a rat BD model with ~60% increases in BAL total protein, BAL cell counts, and lung tissue W/D weight ratios. In contrast, rats receiving SEW-2871 (0.1 mg/kg) 15 minutes after the induction of BD and assessed 4h later exhibited significant lung protection (~50% reduction, p=0.01) reflected by reduced BAL total protein, BAL cytokines concentrations, BAL albumin, BAL total cell count and lung tissue wet/dry (W/D) weights ratio. Microarray analysis at 4hrs revealed a global impact of both BD and SEW on lung gene expression with differential expression of a subclass of genes enriched in immune/inflammation response pathways across the 4 experimental groups. Overall, SEW served to attenuate the BD-mediated ie gene expression upregulation. Two potentially useful biomarkers, Tnf and Ccrl2, exhibited gene dysregulation by microarray analysis, which was validated by qPCR. We conclude that SEW-2871 significantly attenuates BD-induced lung injury and may serve as a potential candidate to improve human lung donor availability and transplantation outcomes. Animals were divided into four groups: sham, BD (A Fogarty catheter 4 Fr. was inserted and secured into the extradural space and inflated to induce BD), SEW (injection of SEW-2871), and BD/SEW. Three replicates each.
Project description:The Forkhead Box f1 (Foxf1) transcriptional factor (previously known as HFH-8 or Freac-1) is expressed in endothelial and smooth muscle cells in the embryonic and adult lung. To assess effects of Foxf1 during lung injury, we used CCl4 injury model. Foxf1+/- mice developed severe airway obstruction and bronchial edema, associated with increased numbers of pulmonary mast cells and increased mast cell degranulation following injury. Pulmonary inflammation in Foxf1+/- mice was associated with diminished expression of Foxf1, increased mast cell tryptase and increased expression of CXCL12, the latter being essential for mast cell migration and chemotaxis. Foxf1 haploinsufficiency caused pulmonary mastocytosis and enhanced pulmonary inflammation following chemically-induced lung injury, indicating an important role for Foxf1 in the pathogenesis of pulmonary inflammatory responses. Keywords: Influence of genetic modification on the pulmonary inflamation Foxf1+/- mice in which the Foxf1 allele was disrupted by an in-frame insertion of a nuclear localizing -galactosidase (-Gal) gene were bred for ten generations into the Black Swiss mouse genetic background. Carbon tetrachloride (CCl4; Sigma, St Louis, MO) was dissolved in mineral oil at a 1:20 ratio v/v and a single intraperitoneal (i.p.) injection of CCl4 (0.5 l of CCl4/ 1g of body weight) was administered to male Foxf1+/- mice or their wild type (WT) littermates as described.
Project description:Aberrant expression of master phenotype regulators by lung fibroblasts may play a central role in idiopathic pulmonary fibrosis (IPF). Interrogating IPF fibroblast transcriptome datasets, we identified Forkhead Box F1 (FOXF1), a DNA-binding protein required for lung development, as a candidate actor in IPF. Thus, we determined FOXF1 expression levels in fibroblasts cultured from normal or IPF lungs in vitro, and explored FOXF1 functions in these cells using transient and stable loss-of-function and gain-of-function models. FOXF1 mRNA and protein were expressed at higher levels in IPF compared with controls. In normal lung fibroblasts, FOXF1 repressed key fibroblast functions such as proliferation, survival, and expression of collagen-1 (COL1) and actin related protein 2/3 complex, subunit 2 (ARPC2). ARPC2 knockdown mimicked FOXF1 overexpression with regard to proliferation and COL1 expression. FOXF1 expression was induced by the antifibrotic mediator prostaglandin E2 (PGE2). Ex vivo, FOXF1 knockdown conferred CCL-210 lung fibroblasts the ability to implant and survive in uninjured mouse lungs. In IPF lung fibroblasts, FOXF1 regulated COL1 but not ARPC2 expression. In conclusion, FOXF1 functions and regulation were consistent with an antifibrotic role in lung fibroblasts. Higher FOXF1 levels in IPF fibroblasts may thus participate in a compensatory response to fibrogenesis. Lung fibroblasts derived from 4 different IPF patients (P313, P355, P375 and P426) were transiently transfected with pcfoxf1 or control pcDNA3.1-constructs. Total RNAs were extracted 24 h after transfection and hybridized on microarrays. One color experiment with 2 experimental conditions: pcfoxf1 and pcDNA3.1
Project description:The Forkhead Box f1 (Foxf1) transcriptional factor (previously known as HFH-8 or Freac-1) is expressed in endothelial and smooth muscle cells in the embryonic and adult lung. To assess effects of Foxf1 during lung injury, we used CCl4 injury model. Foxf1+/- mice developed severe airway obstruction and bronchial edema, associated with increased numbers of pulmonary mast cells and increased mast cell degranulation following injury. Pulmonary inflammation in Foxf1+/- mice was associated with diminished expression of Foxf1, increased mast cell tryptase and increased expression of CXCL12, the latter being essential for mast cell migration and chemotaxis. Foxf1 haploinsufficiency caused pulmonary mastocytosis and enhanced pulmonary inflammation following chemically-induced lung injury, indicating an important role for Foxf1 in the pathogenesis of pulmonary inflammatory responses. Keywords: Influence of genetic modification on the pulmonary inflamation