This study characterizes the response of primary human endothelial cells (human umbilical vein endothelial cells, HUVECs) to the relative shear stress changes that occur during the initiation of arteriogenesis at the entrance regions to a collateral artery network. HUVECs were preconditioned to a baseline level of unidirectional shear of 15 dynes/cm2 for 24 hours. After 24 hours preconditioning, HUVECs were subjected to an arteriogenic stimulus that mimics the shear stress changes observed in the opposing entrance regions into a collateral artery network. The arteriogenic stimulus consisted of a 100% step wise increase in shear stress magnitude to a unidirectional 30 dynes/cm2 in either the same or opposite direction of the preconditioned shear stress. This simulates either the feeding entrance to the collateral artery circuit or the region that drains into the vasculature downstream of an obstruction in a major artery, respectively. In vivo analysis of collateral growth in the mouse hindlimb showed enhanced outward remodeling in the re-entrant (direction reversing) region that reconnects to the downstream arterial tree, suggesting reversal of shear stress direction as a key enhancer of arteriogenesis. Transcriptional profiling using microarray techniques identified that the reversal of shear stress direction, but not an increase in shear stress alone, yielded a broad-based enhancement of the mechanotransduction pathways necessary for the induction of arteriogenesis.
Mechanisms of Amplified Arteriogenesis in Collateral Artery Segments Exposed to Reversed Flow Direction.
Specimen part
View SamplesExpression data from pancreatic cancer cell lines and non-neoplastic pancreatic cell line HPDE
Cyclooxygenase-deficient pancreatic cancer cells use exogenous sources of prostaglandins.
Sex, Specimen part, Disease, Cell line
View SamplesMechanical Stimuli are arguably the most important aetiolgical factors in osteoarthritis (OA) development. Not only do we see disease arising from joints where the cartilage has sustained direct (e.g. intraarticular fracture) or indirect (e.g. meniscal injury) trauma, but mechanical factors are considered, at least partly, to explain the disease associations with aging and obesity. It is now well established that OA is not simply due to repeated wear and tear, leading to attrition of the articular surfaces, but that it requires activation of a number of inflammatory genes, which drive catabolic protease activity in the joint. These enzymes lead to breakdown of the major extracellular matrix components of cartilage, namely type II collagen, and the proteoglycan, aggrecan. Although it is unclear precisely which enzymes are responsible for matrix breakdown in human OA, Glasson et al showed that deletion of the aggrecan degrading enzyme, ADAMTS5 substantially protected the joint from surgically induced murine OA suggesting that it is a major aggrecanase in the mouse.
Joint immobilization prevents murine osteoarthritis and reveals the highly mechanosensitive nature of protease expression in vivo.
No sample metadata fields
View SamplesExpression of the proendocrine gene neurogenin 3 (Ngn3) is required for the development of pancreatic islets. In order to better characterize the molecular events regulated by Ngn3 during development, we have determined the expression profile of differentiating murine embryonic stem cells (mESCs) uniformly induced to overexpress Ngn3. An ESC line was created that allows for the induction of Ngn3 by adding doxycycline (Dox) to the culture medium. Genome-wide microarray analysis was performed to identify genes regulated by Ngn3 in a variety of both undifferentiated and differentiated conditions. Characterization of pancreatic developmental markers during embryoid body (EB) formation revealed an optimum context for Ngn3 induction. Neuroendocrine genes including neurogenic differentiation 1 (NeuroD1) and single minded 1 (Sim1) were found to be significantly upregulated. Genes regulated by Ngn3 independent of the context were analyzed using systematic gene ontology tools and revealed Notch signaling as the most significantly regulated signaling pathway (p=0.009). This result is consistent with the hypothesis that Ngn3 expression makes the cell competent for Notch signaling to be activated and conversely, more sensitive to Notch signaling inhibition. Indeed, EBs induced to express Ngn3 were significantly more sensitive to gamma-secretase inhibitor-mediated Notch signaling inhibition (p<0.0001). Moreover, we find that Ngn3 induction in differentiating ESCs results in significant increases in insulin, glucagon, and somatostatin transcription.
Differentiation of embryonic stem cells conditionally expressing neurogenin 3.
No sample metadata fields
View SamplesIn order to study the microglia contribution in neurodegeneration more specifically we established a mouse model of prion disease in which the 79A murine prion strain was introduced by an intraperitoneal route into BALB/cJFms-EGFP/- mice, which express Enhanced Green Fluorescent Protein (EGFP) under control of the C-fms operon. Samples were taken at time points during disease progression and histological analysis of the brain and transcriptional analysis of isolated microglia was carried out. The analysis of isolated microglia revealed a disease specific, highly pro-inflammatory signature in addition to an up-regulation of genes associated with metabolism, respiratory stress and DNA repair. This study strongly supports the growing recognition of the importance of microglia within the prion disease process and identifies the nature of the response through gene expression analysis of isolated microglia.
Defining the Microglia Response during the Time Course of Chronic Neurodegeneration.
Sex, Specimen part
View SamplesGene expression analysis of pancreatic cancer associated fibroblasts and control fibroblasts
Overexpression of smoothened activates the sonic hedgehog signaling pathway in pancreatic cancer-associated fibroblasts.
Specimen part, Disease
View SamplesSSEA1+ c-kit+cells sorted from mouse embryonic stem cells differentiated for 4 days in 10uM Retinoic acid do not form teratomas when transplated into SCID mice while Pten-/- cells do.
Loss of Pten causes tumor initiation following differentiation of murine pluripotent stem cells due to failed repression of Nanog.
Specimen part
View SamplesThe function of Structural maintenance of chromosome flexible domain containing 1 (Smchd1) was examined during mouse preimplantation development using an siRNA knockdown approach. Transient SMCHD1 deficiency during the period between fertilization and morula/early blastocyst stage compromised embryo viability and resulted in reduced cell number, reduced embryo diameter, and reduced nuclear volumes at the morula stage. RNAseq analysis of Smchd1 knockdown morulae revealed aberrant increases in expression of mRNAs related to the trophoblast lineage, indicating SMCHD1 inhibits trophoblast lineage gene expression and promotes inner cell mass formation. siRNA knockdown also reduced expression of cell proliferation genes, including S-phase kinase-associated protein 2 (Skp2). Smchd1 expression was elevated in Caudal type homeobox transcription factor 2 (Cdx2)-/- blastocysts, indicating enriched expression, and further indicating a role in inner cell mass development. These results indicate that Smchd1 plays dual roles in the preimplantation embryo, promoting a lineage-appropriate pattern of gene expression supporting inner cell mass formation, whilst controlling lineage formation and gene expression in the trophectoderm. Overall design: Effects of SMCHD1 siRNA knockdown were tested in mouse embryos
Novel key roles for structural maintenance of chromosome flexible domain containing 1 (Smchd1) during preimplantation mouse development.
Treatment, Subject
View SamplesRNA-SEQ of mutants B cell for IgH 3''RR and Emu Overall design: CD43- splenic B-cells from wt, Eµ-deficient or 3''RR deficient mice, non stimulated (NS) or stimulated (S) with 5mg/ml LPS.
E<sub>μ</sub> and 3'RR IgH enhancers show hierarchic unilateral dependence in mature B-cells.
No sample metadata fields
View SamplesThe IgH 3' regulatory region (3'RR) controls class switch recombination (CSR) and somatic hypermutation (SHM) in B cells. The mouse 3'RR contains four enhancer elements with hs1,2 flanked by inverted repeated sequences and the center of a 25-kb palindrome bounded by two hs3 enhancer inverted copies (hs3a and hs3b). hs4 lies downstream of the palindrome. Evolution maintained in mammals this unique palindromic arrangement suggesting that it is functionally significant. We report that deconstructing the palindromic IgH 3'RR strongly impacts its function even when enhancers are preserved. CSR and IgH transcription appear poorly dependent from the 3'RR architecture and are more or less preserved provided 3'RR enhancers are present. By contrast, an “architectural effect” significantly lowers VH germline transcription, AID recruitment and SHM. In conclusion, this work indicates that the IgH 3'RR does not simply pile up enhancer units but also optimally expose them into a functional architecture of crucial importance. Overall design: RNAseq analysis of B-cell splenocytes with (S=stimulated) or without (R=resting) LPS activation from wt, delta2leftPAL, and deltaIRIS mice.
Deciphering the importance of the palindromic architecture of the immunoglobulin heavy-chain 3' regulatory region.
Specimen part, Cell line, Subject
View Samples