Project description:Arteriovenous malformations (AVMs) are characteristic of hereditary hemorrhagic telangiectasia (HHT). We used single cell RNA sequencing (scRNA-seq) to analyzed the pulmonary ECs in mice with endothelial-specific deletion of Alk1 gene.
Project description:Arteriovenous malformations (AVMs) are characteristic of hereditary hemorrhagic telangiectasia (HHT). We used single cell RNA sequencing (scRNA-seq) to trace pulmonary EC lineages in mice with endothelial-specific deletion of Alk1 gene.
Project description:Distinct endothelial cell cycle states (early G1 vs. late G1) provide different “windows of opportunity” to enable the differential expression of genes that regulate venous and arterial specification, respectively. Endothelial cell cycle control and arterial-venous identities are disrupted in vascular malformations including arteriovenous (AV) shunts which is a hallmark of hereditary hemorrhagic telangiectasia (HHT). We show how endothelial cell late G1 arrest induced by Palbociclib modulates the expression of genes regulating arterio-venous identity and prevents AVM development induced by BMP9/10 inhibition.
Project description:Background: Hereditary hemorrhagic telangiectasia (HHT) is an inherited vascular disorder characterized by arteriovenous malformations (AVMs). Loss-of-function mutations in Activin receptor-like kinase 1 (ALK1) cause type 2 HHT and Alk1 knockout (KO) mice develop AVMs along with overactivation of VEGFR2/PI3K/AKT signaling. The full spectrum of signaling alterations resulting from ALK1 mutations remains unknown, and more effective and specific inhibitors to combat AVM formation in patients are needed. Methods: Single-cell RNA sequencing of endothelial-specific Alk1 KO mouse retinas and controls was performed. Overexpression of fluid shear stress signaling signatures including the mechanosensitive ion channel PIEZO1 was confirmed in mouse and human HHT2 lesions. Genetic and pharmacological PIEZO1 inhibition was tested in Alk1 KO mice, along with downstream PIEZO1 signaling. Results: A cluster of Alk1 mutant endothelial cells with altered arterio-venous identity overexpressed pathways related to fluid shear stress, hypoxia, inflammation, cell cycle and VEGFR2/PI3K/AKT signaling. Piezo1 deletion and pharmacological inhibition in Alk1-deficient mice mitigated AVM formation, whereas Piezo1 overexpression enhanced AVM formation induced by ALK1 ligand blockade. Mechanistically, PIEZO1 inhibition reduced elevated VEGFR2/AKT, ERK5-p62-KLF4, eNOS, hypoxia, proliferation and inflammation in ALK1 deficient endothelium. Conclusions: PIEZO1 expression and signaling are elevated in HHT2. PIEZO1 blockade reduces AVM formation and alleviates cellular and molecular hallmarks of ALK1-deficient cells. This finding provides new insights into the mechanistic underpinnings of ALK1-related vascular diseases and identifies potential therapeutic targets to prevent AVMs.
Project description:Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant vascular dysplasia characterized by epistaxis, mucocutaneous telangiectases, and arteriovenous malformations (AVM) in visceral organs. In this study, we carried out a liquid biopsy consisting in the isolation of total RNA from plasma exosomes samples from HHT type 1 (HHT1 group) and type 2 (HHT2 group) patients, and healthy relatives (Control group). Upon gene expression data processing and normalization, a bioinformatics analysis was performed for the study of principal components, hierarchical clustering and pairwise comparisons between HHT samples and control group. Results were evaluated in a further validation cohort of HHT and healthy donors by real time PCR and the diagnosis value of exosomal miRNA determined by the ROC curves analysis. We found that exosomal miRNA expression signature clearly distinguishes among healthy and HHT samples and types. Thus, we identified a disease-associated molecular fingerprint of 35 miRNAs over-represented, being 8 specifics for HHT1 and 11 for HHT2; and 30 under-represented, including 9 distinctive for HHT1 and 9 for HHT2. These exosome-transported miRNAs have diagnosis value for HHT, and even allow to distinguish between HHT1 and HHT2.