Project description:The elaborate patterning of coronary arteries critically supports the high metabolic activity of the beating heart. How coronary endothelial cells coordinate hierarchical vascular remodeling and achieve arteriovenous specification remains largely unknown. Understanding the molecular and cellular cues that pattern coronary arteries is crucial to develop innovative therapeutic strategies that restore functional perfusion within the ischemic heart. Single-cell transcriptomics were used to delineate heterogeneous transcriptional states of the developing and mature coronary endothelium with a focus on sprouting endothelium and arterial cell specification. We discovered that a tip-cell-to-artery specification mechanism drives arterialization of the intramyocardial plexus and endocardial tunnels throughout life. We also identified non-overlapping intramyocardial and subepicardial tip cell populations with differential gene expression profiles and regulatory pathways, suggesting that differential sprouting programs govern the formation and specification of the venous and arterial coronary plexus.
Project description:Blood vessel growth and remodelling are essential during embryonic development and disease pathogenesis. The diversity of endothelial cells (ECs) is transcriptionally evident and ECs undergo dynamic changes in gene expression during vessel growth and remodelling.Here, we investigated the role of the histone acetyltransferase HBO1 (KAT7), which is important for activating genes during development and histone H3 lysine 14 acetylation (H3K14ac). Loss of HBO1 and H3K14ac impaired developmental sprouting angiogenesis and reduced pathological EC overgrowth in the retinal endothelium. Single-cell RNA-sequencing of retinal ECs revealed an increased abundance of tip cells in Hbo1 deleted retinas, which lead to EC overcrowding in the retinal sprouting front and prevented efficient tip cell migration. We found that H3K14ac was highly abundant in the endothelial genome in both intra- and intergenic regions suggesting that the role of HBO1 is as a genome organiser that promotes efficient tip cell behaviour necessary for sprouting angiogenesis.
Project description:Blood vessel growth and remodelling are essential during embryonic development and disease pathogenesis. The diversity of endothelial cells (ECs) is transcriptionally evident and ECs undergo dynamic changes in gene expression during vessel growth and remodelling.Here, we investigated the role of the histone acetyltransferase HBO1 (KAT7), which is important for activating genes during development and histone H3 lysine 14 acetylation (H3K14ac). Loss of HBO1 and H3K14ac impaired developmental sprouting angiogenesis and reduced pathological EC overgrowth in the retinal endothelium. Single-cell RNA-sequencing of retinal ECs revealed an increased abundance of tip cells in Hbo1 deleted retinas, which lead to EC overcrowding in the retinal sprouting front and prevented efficient tip cell migration. We found that H3K14ac was highly abundant in the endothelial genome in both intra- and intergenic regions suggesting that the role of HBO1 is as a genome organiser that promotes efficient tip cell behaviour necessary for sprouting angiogenesis.
Project description:We exploited a three-dimensional model of sprouting angiogenesis in which the phenotypic switch from quiescent ECs to tip cells was triggered by VEGF-A. The information obtained about modulated miRNAs and their related protein-coding gene targets was used to generate a co-expression network encompassing gene modules that are post-transcriptionally regulated and whose activity is required for sprouting.
Project description:We exploited a three-dimensional model of sprouting angiogenesis in which the phenotypic switch from quiescent ECs to tip cells was triggered by VEGF-A. The information obtained about modulated miRNAs and their related protein-coding gene targets was used to generate a co-expression network encompassing gene modules that are post-transcriptionally regulated and whose activity is required for sprouting.
Project description:We exploited a three-dimensional model of sprouting angiogenesis in which the phenotypic switch from quiescent ECs to tip cells was triggered by VEGF-A. The information obtained about modulated miRNAs and their related protein-coding gene targets was used to generate a co-expression network encompassing gene modules that are post-transcriptionally regulated and whose activity is required for sprouting.
Project description:We exploited a three-dimensional model of sprouting angiogenesis in which the phenotypic switch from quiescent ECs to tip cells was triggered by VEGF-A. The information obtained about modulated miRNAs and their related protein-coding gene targets was used to generate a co-expression network encompassing gene modules that are post-transcriptionally regulated and whose activity is required for sprouting.
Project description:The development of the vertebrate vascular system is mediated by both genetic patterning of vessels and by angiogenic sprouting in response to hypoxia. Both of these processes depend on the detection of environmental guidance cues by endothelial cells. A specialized subtype of endothelial cell known as the tip cell is believed to be involved in the detection and response to these cues, but the molecular signaling pathways utilized by tip cells to mediate tissue vascularization remain largely uncharacterized. To identify genes critical to tip cell function, we have developed a method to isolate them using laser capture microdissection, permitting comparison of RNA extracted from endothelial tip cells to that of endothelial stalk cells using microarray analysis. Genes enriched in tip cells include ESM-1, Angiopoietin-2, and SLP-76. CXCR4, a receptor for the chemokine SDF-1, was also identified as a tip cell-enriched gene, and we provide evidence for a novel role for this receptor in mediating tip cell morphology and vascular patterning in the neonatal retina.