Project description:Lifestyle and genetic factors can lead to the development of atherosclerosis and, ultimately, cardiovascular adverse events. Rodent models are commonly used to investigate mechanism(s) of atherogenesis. However, the 3Rs principles, aiming to limit animal testing, encourage the scientific community to develop new physiologically relevant in vitro alternatives. Leveraging the 96-chip OrganoPlate®, a microfluidic platform, we have established a three-dimensional (3D) model of endothelial microvessels-on-a-chip under flow using primary human coronary arterial endothelial cells. As functional readout, we have set up an assay to measure the adhesion of monocytes to the lumen of perfused microvessels. For monitoring molecular changes in microvessels, we have established the staining and quantification of specific protein markers of inflammation and oxidative stress using high content imaging, as well as analyzed transcriptome changes using microarrays. To demonstrate its usefulness in systems toxicology, we leveraged our 3D vasculature-on-a-chip model to assess the impact of the Tobacco Heating System (THS) 2.2, a candidate modified risk tobacco product, and the 3R4F reference cigarette on the adhesion of monocytic cells to endothelial microvessels. Our results show that THS 2.2 aerosol-conditioned medium had a reduced effect on monocyte-endothelium adhesion compared with 3R4F smoke-conditioned medium. In conclusion, we have established a relevant 3D vasculature-on-a-chip model for investigating leukocyte-endothelial microvessel adhesion. A case study illustrates how the model can be used for product testing in the context of systems toxicology-based risk assessment. The current model and its potential further development options also open perspectives of applications in vascular disease research and drug discovery.
Project description:The control of cell identity is orchestrated by transcriptional and chromatin regulators in the context of specific chromosome structures. With the recent isolation of human naive embryonic stem cells (ESCs) representative of the ground state of pluripotency, it is possible to deduce this regulatory landscape in one of the earliest stages of human development. Here we generate cohesin ChIA-PET chromatin interaction data in naive and primed human ESCs and use it to reconstruct and compare the 3D regulatory landscapes of these two stages of early human development. The results reveal shared and stage-specific regulatory landscapes of topological domains and their subdomains, which consist of CTCF-CTCF/cohesin loops and enhancer-promoter/cohesin loops. The enhancer-promoter loop data reveal that genes with key roles in pluripotency are nearly always regulated by one or more super-enhancers, and show that these genes tend to occur in insulated neighborhoods. Our results reveal the key features of the 3D regulatory landscape of early human cells that form the foundation for embryonic development. ChIP-seq data from naive and primed human embroynic stem cells.
Project description:Tino is an A+U-Rich Element (ARE) binding protein first identified through its ability to bind to bcl-2 mRNA and to contribute to its degradation. It has recently been recognized as a shorter form of the human Mex-3D protein (hMex-3D), one of the four members of the family of Mex-3 RNA-binding phosphoproteins. In C. elegans, ceMex-3 is a translational regulator that plays a key role in early embryonic development and in the maintenance of worm germ line totipotency. To examine the potential functional conservation between ceMex-3 and hMex3, we have used complementary microarray-based approaches to identify mRNAs directly bound to Tino/hMex-3D. Computational analysis of these target mRNAs resulted in the identification of an U-rich, 34- to 39-nucleotide long, consensus, forming loops of variable sizes. Remarkably, more than half of Tino/hMex-3D targets also contain the consensus for Quaking, which is the human ortholog of GLD-1, a regulator of nematode gametogenesis. All together, our results suggest that Tino/hMex-3D belongs to a regulatory circuit of mRNA trans-acting factors involved in cell fate and differentiation. Keywords: RIP-chip and (recombinant)RIP-Chip analysis of Tino/hMEX-3D mRNPs To identify the transcripts directly bound in vivo by Tino/hMex-3D, we have used two complementary strategies. First, using Tino-his transfected HEK293 cells, we have analysed the RNAs immunoprecipitated by Tino/hMex-3D (RNA-IP complexes). Second, we have developed an in vitro nitrocellulose RNA-protein binding assay using a truncated form of Tino, TinoΔRING-his. First for the in vivo approach, we have transiently transfected HEK293 cells with a His-tagged Tino expressing construct (see Materials) and isolated Tino target mRNAs by immunoprecipitation (IP) assays carried out under conditions preserving mRNA-protein complex integrity. Second, for the in vitro approach, cRNAs were prepared from a human placenta cDNA library and incubated with TinoΔRING-his. This deleted form of Tino-his protein conserves its mRNA binding activity. mRNAs directly bound to TinoΔRING-his protein were subsequently isolated using a nitrocellulose RNA-protein binding assay. A supplementary file of ordered genes based on z-ratios, derived from experimental and negative control samples for each Affymetrix probe, is appended below.
Project description:Hox genes are essential regulators of embryonic development. They are activated in a temporal sequence following their topological order within their genomic clusters. Subsequently, states of activity are fine-tuned and maintained to translate into domains of progressively overlapping gene products. While the mechanisms underlying such temporal and spatial progressions begin to be understood, many of their aspects remain unclear. We have systematically analyzed the 3D chromatin organization of Hox clusters in vivo, during their activation using high-resolution circular chromosome conformation capture (4C-seq). Initially, Hox clusters are organized as single 3D chromatin compartments decorated with bivalent chromatin marks. Their progressive transcriptional activation is associated with a dynamic bi-modal 3D organization, whereby the genes switch one after the other, from an inactive to an active 3D compartment. These local 3D dynamics occur within a larger constitutive framework of interactions within the surrounding Topological Associated Domains, which confirms previous results that regulation of this process in primarily cluster intrinsic. The local step-wise progression in time can be stopped and memorized at various body levels and hence it may accounts for the various chromatin architectures previously described at different anterior to posterior body levels for the same embryo at a later stage. ChIP-seq samples (H3K4me3 and H3K27me3) from mouse ES cells and mouse embryonic stage E8.5 pre-somitic mesoderm. Data based on 4 biological samples.
Project description:The ability for cells to sense and respond to microenvironmental signals is influenced by their three dimensional (3D) surroundings, which includes the extracellular matrix (ECM). In the 3D environment, vascular structures supply cells with nutrients and oxygen thus affecting cell responses such as motility. Interpretation of cell motility studies though is often restricted by the applied approaches such as 2D conventional soft lithography methods that have rectangular channel cross-sectional morphology. To better simulate cell responses to vascular supply in 3D, we developed a cell on a chip system with microfluidic channels with curved cross-sections embedded within a 3D collagen matrix that emulates anatomical vasculature more closely than inorganic polymers, thus to mimic a more physiologically relevant 3D cellular environment. To accomplish this, we constructed perfusable microfluidic channels by embedding sacrificial circular gelatin vascular templates in collagen, which were removed through temperature control. Motile breast cancer cells were pre-seeded into the collagen matrix and when presented with a controlled chemical stimulation from the artificial vasculature, they migrated towards the vasculature structure. We believe this innovative vascular 3D ECM system can be used to provide novel insights into cellular dynamics during multidirectional chemokineses and chemotaxis that exist in cancer and other diseases.
Project description:Some molecular chaperones are involved not only in assisting the folding of proteins but also, given appropriate conditions, in their degradation. This is the case of Hsp70 and Hsp90, which in concert with the cochaperone CHIP –an E3 ligase–, direct their bound substrate to degradation through ubiquitination. We have generated complexes between the chaperone (Hsp70 or Hsp90), the cochaperone CHIP and, as substrate, a p53 variant containing the GST protein (p53-TMGST). The two ternary complexes (Hsp70:p53-TMGST:CHIP and Hsp90:p53-TMGST:CHIP) ubiquitinate the substrate, and this is done with a higher efficiency than in the absence of the chaperones. The 3D structures of the two complexes, obtained using a combination of cryoelectron microscopy and crosslinking mass spectrometry, show the substrate located between the chaperone and the cochaperone, which suggests an ubiquitination mechanism. Both complexes are extremely flexible, which is crucial for the ubiquitination process.
Project description:Tumor-associated breast vasculature was laser-cappture microdissected from IDC breast cancer cases. The goal of the study was to characterize the heterogeneity of breast tumor-associated vasculature and identify gene expression signatures predictive of clinical outcome. common reference design, 32 samples
Project description:Early embryo loss affects all mammalian species, including humans and agriculturally important food-producing mammals such as cattle. The developing conceptus (embryo and extra-embryonic membranes) secretes factors which modify the endometrium and can be critical for early pregnancy processes such maternal recognition of pregnancy (MRP) and enhancing uterine receptivity to implantation. For example, a competent bovine conceptus secretes IFNT to initiate MRP. The bovine conceptus also secretes other proteins at the time of MRP, including CAPG and PDI, which are highly conserved among placental mammals. We have previously shown that these proteins act upon the endometrium to modulate receptivity, embryo development, and implantation in species with different implantation strategies (humans and cattle). We hypothesise that developing a novel 3D bovine endometrium on a chip system will enhance our understanding of the role of conceptus-derived factors in altering the endometrium and/or ULF secretion. Here we have developed a 3D bovine endometrium on a chip system, comprising both stromal and epithelial cell culture combined with culture medium flow better mimics the in vivo endometrium and exposure to conceptus-derived factors than conventional 2D endometrial cell culture. We have demonstrated that the conceptus-derived proteins CAPG and PDI modulate the endometrial transcriptome and secretory response to promote pathways associated with early pregnancy and alter ULF composition. This work highlights the critical need for more robust and in vivo-like culture systems to study endometrial-conceptus interactions in vitro to further investigate the role of conceptus derived factors for pregnancy success.