Project description:Shear stress generated by flowing blood has major effects on vascular function. Bends and branches of arteries are exposed to complex blood flow patterns, a mechanical environment that promotes cardiovascular dysfunction and atherosclerosis. The exact mechanisms, by which endothelial cells translate shear stress to physiological and pathophysiological responses remain incompletely understood. Here, we identified perturbations of the ubiquin landscape in endothelial cells driven by shear stress. The integrative analysis of proteome and ubiquitome revealed that non-degradative ubiquitination controls cytoskeleton rearrangements in response to shear stress. These results provide a global view of the contribution of the ubiquitin system during shear stress response.
Project description:Physiological shear stress, produced by blood flow, homeostatically regulates the phenotype of pulmonary endothelial cells exerting anti-inflammatory and anti-thrombotic actions and maintaining normal barrier function. In the pulmonary circulation hypoxia, due to high altitude or diseases such as COPD, causes vasoconstriction, increased vascular resistance and pulmonary hypertension. Hypoxia-induced changes in endothelial function play a central role in the development of this pulmonary hypertension. However, the direct interactive effects of hypoxia and shear stress on the pulmonary endothelial phenotype have not been extensively studied. We cultured human pulmonary microvascular endothelial cells (HPMEC) in normoxia or hypoxia while subjected to physiological shear stress or in static conditions. Unbiased proteomics was used to identify hypoxia-induced changes in protein expression. Using publicly available single cell RNA-seq datasets, differences in gene expression between the alveolar endothelial cells from COPD and healthy lungs were identified. 60 proteins were identified in HPMEC lysates whose expression changed in response to hypoxia in sheared but not in static conditions. mRNA for five of these (ERG, MCRIP1, EIF4A2, HSP90AA1 and DNAJA1) showed similar changes in the endothelial cells of COPD compared to healthy lungs. These data show that the proteomic responses of the pulmonary microvascular endothelium to hypoxia are significantly altered by shear stress and suggest that these differences are important in the development of hypoxic pulmonary vascular disease.
Project description:Laminar shear stress due to constant blood flow is known to play a critical role in maintaining vascular health. In contrast, endothelial cell senescence appears to be closely associated with the incidence of vascular disorder. In an attempt to identify functional biomarkers for age-related vascular health/disease, the present study investigated differential gene expression of young and senescent human umbilical vein endothelial cells (HUVECs) under static and laminar shear stress. We used a cDNA microarray method to compare gene expression profiles of young and senescent HUVECs under static and laminar shear stress conditions. Keywords: stress response, age state analysis
Project description:Laminar shear stress due to constant blood flow is known to play a critical role in maintaining vascular health. In contrast, endothelial cell senescence appears to be closely associated with the incidence of vascular disorder. In an attempt to identify functional biomarkers for age-related vascular health/disease, the present study investigated differential gene expression of young and senescent human umbilical vein endothelial cells (HUVECs) under static and laminar shear stress. We used a cDNA microarray method to compare gene expression profiles of young and senescent HUVECs under static and laminar shear stress conditions. Experiment Overall Design: Senescent cells were prepared by continuous subculture in vitro, and a cone-and-plate device was used to impose laminar shear stress onto cells. Young and senescent cells were exposed to laminar shear stress or maintained under static conditions. Total mRNA was extracted and gene expression profiles were analyzed by cDNA microarray.
Project description:The mechanisms by which physical forces regulate cells to determine complexities of vascular structure and function are enigmatic. Here we show the role the ion channel subunit Piezo1 (FAM38A). Disruption of mouse Piezo1 gene disturbed vascular development and was embryonic lethal within days of the heart beating to cause blood flow. Importance of Piezo channels as sensors of blood flow was indicated by Piezo1 dependence of shear stress-evoked ionic current and calcium influx in endothelial cells and the ability of exogenous Piezo1 to confer shear stress sensitivity on cells that otherwise lacked. Downstream of this calcium influx was proteoase activity and spatial organization of endothelial cells to the polarity of the applied force. Without Piezo1, normal endothelial cell organization was lacking. The data suggest Piezo1 channels as pivotal integrators of vascular architacture with physiological mechanical force.
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
Project description:The role of shear stress, the frictional force of blood flow, on the endothelium has been well documented. Differences in shear stress can have profound effects on endothelial and blood vessel biology. Endothelial cells (ECs), termed endocardial ECs, line the heart chambers and are exposed to complex shear stress patterns. While it has been demonstrated that shear stress is important for heart development, little has been shown on the role of shear stress on adult ECs. 4D-MRI studies demonstrate regional differences in blood residence time. We sought to determine the effect of regional differences in endocardial shear stress on the endocardial transcriptome using RNA sequencing (RNA-seq) on 3 different regions (apex, mid-ventricle, outflow tract) from 8 adult pigs, for a total of 24 RNA-seq assays.
Project description:Background: Endothelial cell (ECs) heterogeneity is an emerging area of research in EC biology. Veins, arteries, and microvascular endothelial cells, termed “vascular-type” heterogeneity in this report, have been shown to have heterogeneity in gene expression and function. In addition to this innate heterogeneity, we hypothesized that different vascular-type ECs would also demonstrate heterogeneity in their response to shear stress. Objectives: We interrogated whether vascular-type ECs would demonstrate variations in transcriptional expression patterns under shear stress. Methods: Human umbilical vein endothelial cells (HUVECs), human pulmonary arterial endothelial cells (HPAECs), and human microvascular endothelial cells (HMVECs) were commercially purchased and subjected to shear stress conditions of 0, 1, 4, and 10 dynes/cm2 of laminar shear stress. After exposure to shear stress, cells were analyzed for cellular alignment and RNA was extracted and evaluated via bulk RNA-sequencing (RNA-seq). Results: All ECs demonstrated significant changes in alignment under shear stress. Shear stress significantly affected the transcriptomes of ECs resulting in differentially expressed genes and pathways; while several genes were differentially expressed across all three vascular-types (44.2%), most differentially expressed genes were limited to 1 or 2 of the vascular-types. Hemostatic and thrombotic genes were found to have differential expression patterns under conditions of shear stress, and VWF demonstrated a pattern of vascular-type heterogeneity in response to shear stress. Conclusions: Shear stress causes changes in cellular alignment and transcriptional patterns in ECs that is dependent upon underlying vascular-type. Therefore, endothelial vascular-type heterogeneity can regulate response to shear stress, especially in hemostatic and thrombotic gene expression.
Project description:Blood flow within the vasculature is a critical determinant of endothelial cell (EC) identity and functionality, yet the intricate interplay of various hemodynamic forces and their collective impact on endothelial and vascular responses are not fully understood. Specifically, the role of hydrostatic pressure in the context of flow response is understudied, despite its known significance in vascular development and disease progression. To address this gap, we developed in vitro models to investigate how pressure influences EC responses to flow. Our study demonstrates that elevated pressure conditions significantly modify shear-induced flow alignment and increase endothelial cell density, a phenomenon often observed in vascular diseases. Utilizing both bulk and single-cell RNA sequencing, we found that while flow is the primary driver of transcriptional changes from static conditions, pressure distinctly modulates this flow response by upregulating gene sets linked to arterial cell phenotypes. When compared to early vascular development stages, pressure was notably associated with gene sets that promote the formation of early hemogenic endothelial cells. Our findings emphasize the necessity of an integrative approach to endothelial cell mechanotransduction, one that encompasses the effects induced by pressure alongside other hemodynamic forces.
Project description:The lymphatic system removes fluid from the interstitial space and returns it to the blood with a tremendous capacity: during inflammation, lymph flow rates can increase dramatically; however, during chronic lymphedema, there is little or no flow. The ability of lymphatic endothelium to sense and actively regulate this function is unknown, and shear stress is likely a key indicator of lymph flow. We profiled gene expression in human dermal microvascular lymphatic endothelial cells exposed to 0, 2 and 20 dyn/cm2 shear stress as representative of chronic lymphedema, normal, and acute inflammatory conditions, respectively. We found important adaptive responses correlated to multiple aspects of lymphatic function. Importantly, shear stress upregulated intracellular water and solute transporters while decreasing cell-cell adhesion and basement membrane components and increasing cell-matrix interactions. This data indicate that during high loading conditions, both passive and active drainage function increases, while conversely when fluid drainage is blocked, transport function is diminished in the lymphatic endothelium. These data demonstrate the first functional-adaptive response of lymphatic endothelium to flow conditions, thus indicating that the lymphatic endothelium plays an active role in regulating their function. Keywords: Shear stress, dose response, cell type comparison Lymphatic endothelial cells were subjected to 0, 2, or 20 dyn/cm2 shear stress; blood endothelial cells were subjected to 0 or 20 dyn/cm2 shear stress. Four samples were used for each cell type/shear level group for a total of 20 samples. Each sample was independently compared to human universal reference RNA via two-color microarray analysis for a total of 20 arrays. In all cases, the experimental samples were labeled with Cy5 dye while the reference RNA was labeled with Cy3.