Identification of transcriptional drifts in endothelial cells associated with environmental changes
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ABSTRACT: Environmental cues, such as shear stress and heterotypic cell interactions play a critical role in endothelial cell function, yet their unique contributions to the endothelial cell transcriptome remain unclear. Using cell preparations from human umbilical cords (ex vivo), we performed individual sample analysis to assess transcriptional drifts associated with environmental changes but independent of sex or background. Global gene expression profiling by RNA-seq, ATACseq, and MS/MS directed proteomics distinguished freshly isolated endothelial cells from genetically matched culture (in vitro) samples. Over 43% of the transcriptome was significantly changed by the in vitro environment. Amongst several signatures, we observed that TGF-beta and BMP target genes were reduced. In contrast, cytoskeleton-based processes and proliferation-related genes were increased. Subjecting cultured cells to long-term shear stress significantly rescued the expression of approximately 17% of genes including targets of BMP and Notch signaling known to be sensitive to flow. In contrast, co-culture of endothelial cells with smooth muscle cells normalized networks related to cell growth and differentiation, clathrin-vesicle related genes, and recovered targets downstream TGF-beta, recovering approximately 9% of the original in vivo signature. Our findings highlight specific genes, pathways and functional features of endothelial cells that require contextual information and exposure to physical forces. This transcriptional modulation is important to consider in all paradigms that are focused on understanding the ability of endothelial cells to maintain homeostasis and respond to disease processes.
Project description:Environmental cues, such as shear stress and heterotypic cell interactions play a critical role in endothelial cell function, yet their unique contributions to the endothelial cell transcriptome remain unclear. Using cell preparations from human umbilical cords (ex vivo), we performed individual sample analysis to assess transcriptional drifts associated with environmental changes but independent of sex or background. Global gene expression profiling by RNA-seq, ATACseq, and MS/MS directed proteomics distinguished freshly isolated endothelial cells from genetically matched culture (in vitro) samples. Over 43% of the transcriptome was significantly changed by the in vitro environment. Amongst several signatures, we observed that TGF-beta and BMP target genes were reduced. In contrast, cytoskeleton-based processes and proliferation-related genes were increased. Subjecting cultured cells to long-term shear stress significantly rescued the expression of approximately 17% of genes including targets of BMP and Notch signaling known to be sensitive to flow. In contrast, co-culture of endothelial cells with smooth muscle cells normalized networks related to cell growth and differentiation, clathrin-vesicle related genes, and recovered targets downstream TGF-beta, recovering approximately 9% of the original in vivo signature. Our findings highlight specific genes, pathways and functional features of endothelial cells that require contextual information and exposure to physical forces. This transcriptional modulation is important to consider in all paradigms that are focused on understanding the ability of endothelial cells to maintain homeostasis and respond to disease processes.
Project description:Environmental cues, such as shear stress and heterotypic cell interactions play a critical role in endothelial cell function, yet their unique contributions to the endothelial cell transcriptome remain unclear. Using cell preparations from human umbilical cords (ex vivo), we performed individual sample analysis to assess transcriptional drifts associated with environmental changes but independent of sex or background. Global gene expression profiling by RNA-seq, ATACseq, and MS/MS directed proteomics distinguished freshly isolated endothelial cells from genetically matched culture (in vitro) samples. Over 43% of the transcriptome was significantly changed by the in vitro environment. Amongst several signatures, we observed that TGF-beta and BMP target genes were reduced. In contrast, cytoskeleton-based processes and proliferation-related genes were increased. Subjecting cultured cells to long-term shear stress significantly rescued the expression of approximately 17% of genes including targets of BMP and Notch signaling known to be sensitive to flow. In contrast, co-culture of endothelial cells with smooth muscle cells normalized networks related to cell growth and differentiation, clathrin-vesicle related genes, and recovered targets downstream TGF-beta, recovering approximately 9% of the original in vivo signature. Our findings highlight specific genes, pathways and functional features of endothelial cells that require contextual information and exposure to physical forces. This transcriptional modulation is important to consider in all paradigms that are focused on understanding the ability of endothelial cells to maintain homeostasis and respond to disease processes.
Project description:Purpose: Environmental cues, such as shear stress and heterotypic cell interactions play a critical role in endothelial cell function, yet their unique contributions to the endothelial cell transcriptome remain unclear. Methods: Using cell preparations from human umbilical cords (ex vivo), we performed individual sample analysis to assess transcriptional drifts associated with environmental changes but independent of sex or background. Global gene expression profiling by RNA-seq, ATACseq, and protein expression by LC-MS distinguished freshly isolated endothelial cells from genetically matched culture (in vitro) samples. Results: Over 43% of the transcriptome was significantly changed by the in vitro environment. Amongst several signatures, we observed that the expression of TGF-beta and BMP target genes were reduced. In contrast, cytoskeleton-based processes and proliferation-related genes were increased. Subjecting cultured cells to long-term shear stress significantly rescued the expression of approximately 17% of genes including targets of BMP and Notch signaling known to be sensitive to flow. In contrast, co-culture of endothelial cells with smooth muscle cells normalized networks related to cell growth and differentiation, clathrin-vesicle related genes, and recovered targets downstream TGF-beta, recovering approximately 9% of the original in vivo signature. Conclusions: Our findings highlight specific genes, pathways and functional features of endothelial cells that require contextual information and exposure to physical forces. This transcriptional modulation is important to consider in all paradigms that are focused on understanding the ability of endothelial cells to maintain homeostasis and respond to disease processes.
Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data. Groups of assays that are related as part of a time series. Computed
Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data.
Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data. Groups of assays that are related as part of a time series. Keywords: time_series_design
Project description:Many studies have characterised the effect of normal laminar shear stress (LSS) on endothelial responses, however elevated shear stress, as would be experienced overlying a stenotic plaque, has not been studied in depth. Therefore we used transcriptomics and related functional analyses to compare cells exposed to laminar shear stress at 15 or 75 dynes/cm2 for 24 hours (LSS15-normal or LSS75-high shear stress). Human umbilical vein endothelial cells (HUVEC n=4 per flow condition from different batches of pooled donor HUVEC p2) were cultured for 24 hours on gelatin coated slides under laminar shear stress of either 15 dynes/cm2 or 75 dynes/cm2 (LSS15 or LSS75) to assess the effect of high shear stress on endothelial cells. Total RNA was obtained using Qiagen kit and array analysis performed by Service XS (Leiden, Netherlands).
Project description:Much remains unknown about the signals that induce early mesoderm to initiate hematopoietic differentiation. Here we show that endoglin (Eng), a receptor for the TGFβ superfamily, identifies all cells with hematopoietic fate in the early embryo. These arise in an Eng+Flk1+ mesodermal precursor population at E7.5, a cell fraction also endowed with endothelial potential. In Eng knockout embryos, hematopoietic colony activity and numbers of CD71+Ter119+ erythroid progenitors were severely reduced. This coincided with severely reduced expression of embryonic globin and key BMP target genes including the hematopoietic regulators Scl, Gata1, Gata2 and Msx-1. To interrogate molecular pathways active in the earliest hematopoietic progenitors, we applied transcriptional profiling to sorted cells from E7.5 embryos. Eng+Flk-1+ progenitors co-expressed TGFβ and BMP receptors and target genes. Furthermore, Eng+Flk-1+ cells presented high levels of phospho-SMAD1/5, indicating active TGFβ and/or BMP signaling. Remarkably, under hematopoietic serum-free culture conditions, hematopoietic outgrowth of endoglin-expressing cells was dependent on TGFβ superfamily ligands: BMP4, BMP2, or TGF-β1. These data demonstrate that the E+F+ fraction at E7.5 represents mesodermal cells competent to respond to TGFb1, BMP4, or BMP2, shaping their hematopoietic development, and that endoglin is a critical regulator in this process by modulating TGF/BMP signaling. E7.5 pooled embryos (25 litters; 300 embryos approximately) were dissected and 3,000 cells were sorted in triplicate for Eng-Flk1-, Eng-Flk1+, Eng+Flk1+, and Eng+Flk1- fractions. Microarray results were analyzed with GeneSpring GX software.
Project description:In this study, we characterized the adaptive response of arterial endothelial cells to acute increases in shear stress magnitude in well-defined in vitro settings. Porcine endothelial cells were preconditioned by a basal level shear stress of 15 ± 15 dynes/cm2 at 1 Hz for 24 hours, and an acute increase in shear stress magnitude (30 ± 15 dynes/cm2) was then applied. The transcriptomics studies using microarray identified genes that were sensitive to the elevated shear magnitude. A significant number of the identified genes in our study are previously unknown as sensitive to shear stress. Porcine endothelial cells were preconditioned by a basal level shear stress of 15 ± 15 dynes/cm2 at 1 Hz for 24 hours, and an acute increase in shear stress magnitude (30 ± 15 dynes/cm2) was then applied. Gene expression at multiple time points was measured using microarray.
Project description:The objective of this study was to advance the understanding of how in vivo arterial shear forces affect vascular endothelial gene expression. Complicated blood flow patterns at arterial branches create small regions that experience fluctuations in shear stress at frequencies higher than the heart rate. To assess whether such temporal variations in shear stress can affect endothelial gene expression, a series of in vitro microarray experiments was performed. The effects of three sinusoidal waveforms (1, 2, and 3 Hz) and one physiological waveform were compared to the expression profiles under steady flow. At each frequency, three levels of mean shear stress (0, 7.5, and 15 dyn/cm2) were used. Porcine aortic endothelial cells were exposed for 24 hours to each combination, replicated four times. Following shear exposure, phase contrast images of the cells were acquired, and RNA was extracted for microarray analysis against about 10,000 porcine oligonucleotides. Cell alignment with the flow was positively correlated with mean shear (p < 0.001) and independent of frequency. A two-way ANOVA identified 232 genes that were differentially regulated by frequency. The frequency sensitive genes were clustered to identify groups of genes exhibiting similar frequency responses. The largest response was seen at 2 Hz. At this frequency, several inflammatory molecules were upregulated, including VCAM, CTGF, TGF-beta2, c-jun, and IL-8, indicating a potential endothelial atherosusceptibility at this frequency. Mean shear significantly affected the expression of ~3,000 genes. Purely oscillatory flow (zero mean shear) enhanced the expression of several growth factors and adhesion molecules (E-selectin, VCAM, MCP-1, IL-8, c-jun), relative to non-reversing flow (15 dyn/cm2 mean shear). The 2 Hz upregulation of certain atherogenic molecules such as VCAM, c-jun, and IL-8 was enhanced as the mean shear was reduced. Thus, the inflammatory response evoked at certain frequencies appears to be exacerbated by low, oscillatory shear. Keywords: Shear stress response