Project description:Arteries are thought to be formed through the induction of a highly conserved arterial genetic programme in a subset of vessels that will later experience an increase in oxygenated blood flow. The initial steps of arterial specification require both VEGF and Notch signalling. Here, we combined inducible genetic mosaics and transcriptomics to modulate and define the function of these signalling pathways in cell proliferation, arteriovenous (AV) differentiation and mobilization. We observed that endothelial cells (ECs) with high VEGF or Notch signalling are intrinsically biased to mobilize and form arteries; nevertheless, they are not genetically pre-determined, and can also form veins. Mechanistically, we found that higher VEGF and Notch signalling in pre-arterial capillaries suppresses Myc-dependent metabolic and cell-cycle activities, promoting the incorporation of ECs in arteries. Mosaic lineage tracing studies revealed that ECs completely lacking the Notch-Rbpj transcriptional activator complex rarely form arteries; however, these cells regained the ability to form arteries when Myc function was suppressed. Thus, arterial development does not require the direct induction of a Notch-dependent arterial differentiation programme, but rather the timely suppression of endothelial cell-cycle progression and metabolism, a process preceding arterial mobilization and complete differentiation.
Project description:This SuperSeries is composed of the following subset Series: GSE34528: Suppression of Progenitor Differentiation Requires the Long Non-Coding RNA ANCR [HG-U133_Plus_2] GSE34766: Suppression of Progenitor Differentiation Requires the Long Non-Coding RNA ANCR [lincRNA 391k Tiling Array V2] Refer to individual Series
Project description:Vascular permeability is frequently associated with inflammation and it is triggered by chemokines and by a cohort of secreted permeability factors, such as VEGF. In contrast, here we showed that the physiological vascular permeability that precedes implantation is directly controlled by progesterone receptor (PR) and it is independent of VEGF. Both global and endothelial-specific deletion of PR block physiological vascular permeability in the uterus while misexpression of PR in the endothelium of other organs results in ectopic vascular leakage. Integration of genome-wide transcriptional profile of endothelium and ChIP-sequencing revealed that PR induces a NR4A1 (Nur77/TR3) specific transcriptional program that broadly regulates vascular permeability in response to progesterone. This program triggers concurrent suppression of several junctional proteins and leads to an effective, timely and venule-specific regulation of vascular barrier function. Silencing NR4A1 blocks PR-mediated permeability responses indicating a direct link between PR and NR4A1. These results reveal a previously unknown function for progesterone receptor on endothelial cell biology with consequences to physiological vascular permeability and implications to the clinical use of progestins and anti-progestins on blood vessel integrity. Examination of PR binding sites in HUVEC cells using ChIP-seq (non-infected-negative control, PR infected followed by ligand treatment-PR+P or vehicle PR)
Project description:Sprouting angiogenesis is a highly dynamic process which relies on the continuous interchange of endothelial cell relative position within the vascular sprout, a process mediated by cell rearrangements. Here we take advantage of a previous identified role of p110a/PI3K regulating endothelial cell motility to address how cell rearrangement and interaction regulate vessel growth. By using advanced fluorescent zebrafish models and a tamoxifen-inducible endothelial-specific gene targeting in the postnatal mouse retina, we demonstrate that inactivation of the p110a isoform of PI3K in endothelial cells is a good model to study cell shuffling in the growing vasculature. We identify that a failure of endothelial cells to rearrange results in cell elongation and inability to stabilize new contacts upon anastomosis. Instead of rearrange, blockade of p110 signaling drive these cells to grow in a three dimension fashion by sending multiple protrusions which lack lumen and fail to stabilize upon anastomosis. Through a combination of in vivo and in vitro approaches together with a global phosphoproteomic screen, we discover that p110a signaling stimulates cell rearrangements by suppressing actomyosin contractility in a myosin light chain phosphatase (MLCP) dependent manner. Together, our findings highlight the importance of cell rearrangement orchestrating several steps within the angiogenic program and uncover a critical role of the p110a/MLCP axis to suppress actomyosin contractility.
Project description:The tumor suppressor protein p53 suppresses cancer by regulating processes such as apoptosis, cell cycle arrest, senescence, and ferroptosis. Whereas numerous p53 target genes have been identified, only a few appear to be critical for the suppression of tumor growth. Additionally, while ferroptosis is clearly implicated in tumor suppression by p53, few p53 target genes with roles in ferroptosis have been identified. We have been studying the activity of germline missense variants of p53 that are hypomorphic. These hypomorphic variants are associated with increased risk for cancer, but they retain the majority of p53 transcriptional function; as such, study of the transcriptional targets of these hypomorphs has the potential to reveal genes that are important for p53-mediated tumor suppression. Here, we identify PLTP (phospholipid transfer protein) as a p53 target gene that shows impaired transactivation by three different cancer-associated p53 hypomorphs: P47S (Pro47Ser, rs1800371), Y107H (Tyr107His, rs368771578), and G334R (Gly334Arg, rs78378222). We show that enforced expression of PLTP potently suppresses colony formation in human tumor cell lines. We also show that PLTP regulates the sensitivity of cells to ferroptosis, which is an iron mediated and lipid peroxide-induced cell death pathway. Taken together, our findings reveal PLTP to be a p53 target gene that is extremely sensitive to p53 transcriptional function, and which has roles in growth suppression and ferroptosis
Project description:Cell cycle progression requires the coordination of cell growth, chromosome replication, and division. Consequently, a functional cell cycle must be coupled with metabolism. However, direct measurements of metabolome dynamics remained scarce, in particular in bacteria. Here, we describe an untargeted metabolomics approach with synchronized Caulobacter crescentus cells to monitor the relative abundance changes of ~400 putative metabolites as a function of the cell cycle. While the majority of metabolite pools remains homeostatic, ~14% respond to cell cycle progression. In particular, sulfur metabolism is redirected during the G1-S transition, and glutathione levels periodically change over the cell cycle with a peak in late S phase. A lack of glutathione perturbs cell size by uncoupling cell growth and division through dysregulation of KefB, a K+/H+ antiporter. Overall, we here describe the impact of the C. crescentus cell cycle progression on metabolism, and in turn relate glutathione and potassium homeostasis to timely cell division.