Actively translating transcriptome (Ribotag) profiling of mouse retinal endothelial cells during postnatal development
ABSTRACT: Angiogenesis, a process mediating the expansion of vascular beds in many physiological and pathological settings, requires dynamic changes in endothelial cell (EC) behavior. The molecular mechanisms governing EC activity during different phases of vascular growth, remodeling, maturation, and quiescence remain elusive. Here, we have employed actively translating transcriptome analysis of mouse retinal ECs for the characterization of dynamic gene expression changes during postnatal development and the identification of critical angiogenic factors.
Project description:Angiogenesis, a process mediating the expansion of vascular beds in many physiological and pathological settings, requires dynamic changes in endothelial cell (EC) behavior. The molecular mechanisms governing EC activity during different phases of vascular growth, remodeling, maturation, and quiescence remain elusive. Here, we have employed actively translating transcriptome analysis of mouse retinal ECs for the characterization of dynamic gene expression changes during postnatal development and the identification of critical angiogenic factors. In silico computational analyses of these data enabled the identification of candidate regulators controlling EC behavior at different developmental checkpoints. The detailed characterization of Mafb, one of the identified candidates, established that this transcription factor controls endothelial sprouting in vitro and in vivo. Integrative analysis of RNA-Seq and ChIP-Seq data defined putative direct Mafb targets, which are repressed or activated by the transcriptional regulator. Together, our results identify novel cell-autonomous regulatory mechanisms controlling sprouting angiogenesis. Overall design: 2 retinas from a mouse were used for single library / 3 biological replicates (individual mouse) per sample / 5 developmental stages of P6, P10, P15, P21 and P50 / EC-specific Mafb conditional KO
Project description:This experiment explored what miRNA differences and similarities exist between endothelial cells obtained from different vascular beds. Seven different endothelial cell (EC) types were grown in basal conditions. RNA was harvested when cells were nearly confluent. miRNAs were evaluated for each EC type in biological replicates.
Project description:The heterogeneity of endothelial cells (ECs), lining blood vessels, across tissues remains incompletely inventoried. We constructed an atlas of >32,000 single-EC transcriptomic data from 11 tissues of the model organism Mus musculus. We propose a new classification of EC phenotypes based on transcriptome signatures and inferred putative biological features. We identified top-ranking markers for ECs from each tissue. ECs from different vascular beds (arteries, capillaries, veins, lymphatics) resembled each other across tissues, but only arterial, venous and lymphatic (not capillary) ECs shared markers, illustrating a greater heterogeneity of capillary ECs. We identified high-endothelial-venule and lacteal-like ECs in the intestines, and angiogenic ECs in healthy tissues. Metabolic transcriptomes of ECs differed amongst spleen, lung, liver, brain and testis, while being similar for kidney, heart, muscle and intestines. Within tissues, metabolic gene expression was heterogeneous amongst ECs from different vascular beds, altogether highlighting large EC heterogeneity.
Project description:We developed a new technique named as Differential Systemic Decellularization in vivo (DISDIVO) for the molecular profiling of vascular beds throughout the body. This method can by applied to murine models. Thus, the data provided here correspond to mice vascular beds obtained in vivo by DISDIVO.
Project description:Gene expression profiles were used to identify pathways common to arteries from different vascular beds. We used the Illumina Sentrix-6 whole-genome microarray platform to identify genes that are expressed in common between abdominal aorta and intracranial arteries of the circle of Willis. Keywords: Characterization of expression in normal arteries from different vascular beds: intracranial arteries and abdominal aorta. Overall design: Intracranial vessels and abdominal aortae were obtained from cadavers and preserved in RNAlater. RNA was isolated from single artery samples.
Project description:Endothelial cells (EC) lining arteries and veins have distinct molecular and functional signatures. The (epi)genetic regulatory mechanisms underlying this heterogeneity in human EC are incompletely understood. Using genome-wide microarray screening we established a specific fingerprint of freshly isolated arterial (HUAEC) and venous EC (HUVEC) from human umbilical cord comprising 64 arterial and 12 venous genes, representing distinct functions and pathways. Among the arterial genes were 8 transcription factors, including HEY2, a downstream target of Notch signaling and the current ‘golden standard’ pathway for arterial EC specification. Short-term culture of HUAEC or HUVEC abrogated differential gene expression resulting in a default state. Erasure of arterial gene expression was at least in part due to loss of canonical Notch activity and HEY2 expression. Notably, nCounter analysis revealed that restoring HEY2 expression or Delta-like 4 (Dll4)-induced Notch signaling in cultured HUVEC or HUAEC only partially reinstated the arterial EC gene signature while combined overexpression of the 8 transcription factors restored this fingerprint much more robustly. Each transcription factor had a different impact on gene regulation, with some stimulating only few and others boosting a large proportion of arterial genes. Interestingly, although there was some overlap and cross-regulation, the transcription factors largely complemented each other in regulating the arterial EC gene profile. Thus, our study showed that Notch signaling determines only part of the arterial EC signature and identified additional novel and complementary transcriptional players in the complex regulation of human arteriovenous EC identity To identify an arteriovenous (AV) fingerprint in human endothelial cells (EC) across different vascular beds, we used microarrays on RNA from 38 EC samples corresponding to 6 cultured human arterial-EC types (hepatic artery EC or HHAEC, N=3; aorta EC or HAEC, N=2; coronary artery EC or HCAEC, N=2; iliac artery EC or HIAEC, N=2; pulmonary artery EC or HPAEC, N=3; and umbilical artery EC or HUAEC-C, N=5), 4 cultured human venous-EC types (hepatic vein EC or HHVEC, N=3; iliac vein EC or HIVEC, N=3; pulmonary vein EC or HPVEC, N=2; and umbilical vein EC or HUVEC-C, N=5), freshly isolated HUAEC (HUAEC-F, N=4) and freshly isolated HUVEC (HUVEC-F, N=4). Due to the difficulty to obtain biopsies from healthy donors, we did not have access to freshly isolated aEC or vEC matched for all cultured EC types.
Project description:Transplanting vascular endothelial cells (ECs) to support metabolism and express regenerative paracrine factors is a strategy to treat vasculopathies and to promote tissue regeneration. However, transplantation strategies have been challenging to develop because ECs are difficult to culture and little is known about how to sustain their vascular identity and direct them to form long-lasting new vessels or engraft into existing ones. We found that multiple non-vascular cell types transiently expressed EC markers after enforced expression of the transcription factors, Etv2, Erg, and Fli1. However, only mid-gestational amniotic cells could be converted to cells that maintained EC gene expression and proliferated in culture to yield billions of vascular cells. Even so, these converted cells performed sub-optimally in assays of EC function. We used constitutive Akt signaling to mimic the shear forces of the vascular environment and promote EC survival in an effort to correct the deficiencies of the converted cells. Akt signaling increased gene expression of EC morphogenesis genes, including Sox17, shifted the genomic targeting of Fli1 to favor nearby Sox consensus sites, and enhanced the in vivo vascular function of EC-like converted cells. Enforced expression of Sox17 was dispensable for broad EC gene activation, but indispensable for vascular engraftment and reperfusion of ischemic tissue. Our results identify a transcription factor network comprised of Ets and Sox17 factors that specifies and sustains endothelial cell fate and function. This work shows that the commonly used criterion of transcriptional similarity for cell conversion can fail to predict in vivo vascular function. Our approach shows that stringent functional testing in vitro and in vivo is necessary to validate engineered endothelial cell grafts. Overall design: Transcriptome sequencing of endothelial cells and amniotic cells
Project description:The carboxy-terminal domain (CTD) of RNA polymerase II (Pol II) consists of heptad repeats with the consensus motif Y1-S2-P3-T4-S5-P6-S7. Dynamic phosphorylation of the CTD coordinates Pol II progression through the transcription cycle. Monoclonal antibodies have been used to study in vivo the potentially phosphorylated CTD amino acids (Y1, S2, T4, S5 and S7). However, the epitopes detected by antibodies can be masked by proteins or modifications at neighbouring sites. Therefore, the effectiveness of antibodies in western blot or ChIP analysis reflects the number of accessible CTD phosphorylation marks, but not the total number of phosphorylations. Most importantly, CTD phospho-specific antibodies do not provide any heptad - (location) specific information of CTD phosphorylation. Due to these limitations, the principles and patterns of CTD phosphorylation remained elusive. Here, we use genetic and mass spectrometric approaches to directly detect and map phosphosites along the entire CTD. We confirm phosphorylation of CTD residues Y1, S2, T4, S5 and S7 in mammalian and yeast cells. Although specific phosphorylation signatures dominate, adjacent CTD repeats can be differently phosphorylated, leading to a high variation of coexisting phosphosites in mono- and di-heptad CTD repeats. Inhibition of CDK9 kinase specifically reduces S2 phosphorylation levels within the CTD.
Project description:Although the conserved AAA ATPase – bromodomain factor, ATAD2, has been described as a transcriptional co-activator upregulated in many cancers, its function remains poorly understood. Here, using a combination of ChIP-seq, ChIP-proteomics and RNA-seq experiments in embryonic stem cells, we found that Atad2 is an abundant nucleosome-bound protein present on active genes, associated with chromatin remodelling, DNA replication and DNA repair factors. A structural analysis of its bromodomain and subsequent investigations demonstrate that histone acetylation guides ATAD2 to chromatin, resulting in an overall increase of chromatin accessibility and histone dynamics, which is required for the proper activity of the highly expressed gene fraction of the genome. While in exponentially growing cells Atad2 appears dispensable for cell growth, in differentiating ES cells, Atad2 becomes critical in sustaining specific gene expression programs, controlling proliferation and differentiation. Altogether, this work defines Atad2’s function as a facilitator of general chromatin-templated activities such as transcription. Transcriptomic analyses comparing ES cells stably expressing anti-Atad2 shRNA versus cells expressing control shRNA, in day 3 LIF (-) differentiating ES cells (3 replicates for each condition) were performed using the Illumina MouseWG-6 v2.0 expression beadchip technology