scholarly journals Activation of Smad 2/3 signaling by low shear stress mediates artery inward remodeling

2019 ◽  
Author(s):  
Elizabeth Min ◽  
Nicolas Baeyens ◽  
Rui Hu ◽  
Zhenwu Zhuang ◽  
Minghao Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Shear Stress ◽  
Fluid Shear Stress ◽  
Nuclear Translocation ◽  
Transmembrane Protein ◽  
Low Flow ◽  
Type I ◽  
Vessel Remodeling ◽  
Flow Activation ◽  
Artery Remodeling

AbstractRationaleBlood vessel remodeling in response to changes in tissue demand is an important aspect of fitness and is often compromised in vascular disease. Endothelial cell (EC) sensing of fluid shear stress (FSS) governs vessel remodeling to maintain FSS at a specific magnitude or set point in healthy vessels.ObjectiveThe purpose of this study was to understand how shear stress-regulated Smad 2/3 contributes to artery remodeling.Methods and ResultsWe found that shear stress induces Smad 2/3 phosphorylation, nuclear translocation, and gene expression in ECs. Nuclear translocation and gene expression are maximal at low and decrease at high FSS. Reducing flow in the mouse carotid by ligation of branch vessels induces Smad2 nuclear localization in vivo. Activation of Smad 2/3 by FSS requires the Type I TGFβ family receptor Alk5 and the transmembrane protein Neuropilin-1. Flow activation of Smad 2/3 is mediated by increased sensitivity to BMP9 but not BMP10 or TGFβ. By contrast, flow activation of Smad 1/5 is maximal at physiological FSS and requires BMP9 or 10 binding to Alk1 and Endoglin. EC-specific deletion of Alk5 in mice blocks low flow-induced inward remodeling after carotid ligation.ConclusionsTogether, these data elucidate a novel pathway that mediates low flow-induced inward artery remodeling. These results may be relevant to inward remodeling in diseased vessels where Smad 2/3 is activated by pathological stimuli.

Activation of Smad2/3 signaling by low fluid shear stress mediates artery inward remodeling

2021 ◽  
Vol 118 (37) ◽  
pp. e2105339118
Author(s):  
Hanqiang Deng ◽  
Elizabeth Min ◽  
Nicolas Baeyens ◽  
Brian G. Coon ◽  
Rui Hu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Fluid Shear Stress ◽  
Transforming Growth Factor ◽  
Nuclear Translocation ◽  
Transmembrane Protein ◽  
Type I ◽  
Fluid Shear ◽  
Neuropilin 1 ◽  
Morphogenetic Protein ◽  
Artery Remodeling

Endothelial cell (EC) sensing of wall fluid shear stress (FSS) from blood flow governs vessel remodeling to maintain FSS at a specific magnitude or set point in healthy vessels. Low FSS triggers inward remodeling to restore normal FSS but the regulatory mechanisms are unknown. In this paper, we describe the signaling network that governs inward artery remodeling. FSS induces Smad2/3 phosphorylation through the type I transforming growth factor (TGF)-β family receptor Alk5 and the transmembrane protein Neuropilin-1, which together increase sensitivity to circulating bone morphogenetic protein (BMP)-9. Smad2/3 nuclear translocation and target gene expression but not phosphorylation are maximal at low FSS and suppressed at physiological high shear. Reducing flow by carotid ligation in rodents increases Smad2/3 nuclear localization, while the resultant inward remodeling is blocked by the EC-specific deletion of Alk5. The flow-activated MEKK3/Klf2 pathway mediates the suppression of Smad2/3 nuclear translocation at high FSS, mainly through the cyclin-dependent kinase (CDK)-2-dependent phosphosphorylation of the Smad linker region. Thus, low FSS activates Smad2/3, while higher FSS blocks nuclear translocation to induce inward artery remodeling, specifically at low FSS. These results are likely relevant to inward remodeling in atherosclerotic vessels, in which Smad2/3 is activated through TGF-β signaling.

scholarly journals Epigenetic Changes During Mechanically Induced Osteogenic Lineage Commitment

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Julia C. Chen ◽  
Mardonn Chua ◽  
Raymond B. Bellon ◽  
Christopher R. Jacobs
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Shear Stress ◽  
Fluid Shear Stress ◽  
Methylation Status ◽  
Lineage Commitment ◽  
Fluid Shear ◽  
Osteogenic Lineage ◽  
Osteogenic Markers ◽  
Heterochromatin Structure

Osteogenic lineage commitment is often evaluated by analyzing gene expression. However, many genes are transiently expressed during differentiation. The availability of genes for expression is influenced by epigenetic state, which affects the heterochromatin structure. DNA methylation, a form of epigenetic regulation, is stable and heritable. Therefore, analyzing methylation status may be less temporally dependent and more informative for evaluating lineage commitment. Here we analyzed the effect of mechanical stimulation on osteogenic differentiation by applying fluid shear stress for 24 hr to osteocytes and then applying the osteocyte-conditioned medium (CM) to progenitor cells. We analyzed gene expression and changes in DNA methylation after 24 hr of exposure to the CM using quantitative real-time polymerase chain reaction and bisulfite sequencing. With fluid shear stress stimulation, methylation decreased for both adipogenic and osteogenic markers, which typically increases availability of genes for expression. After only 24 hr of exposure to CM, we also observed increases in expression of later osteogenic markers that are typically observed to increase after seven days or more with biochemical induction. However, we observed a decrease or no change in early osteogenic markers and decreases in adipogenic gene expression. Treatment of a demethylating agent produced an increase in all genes. The results indicate that fluid shear stress stimulation rapidly promotes the availability of genes for expression, but also specifically increases gene expression of later osteogenic markers.

scholarly journals Influence of Type I Fimbriae and Fluid Shear Stress on Bacterial Behavior and Multicellular Architecture of Early Escherichia coli Biofilms at Single-Cell Resolution

2018 ◽  
Vol 84 (6) ◽  
Author(s):  
Liyun Wang ◽  
Robert Keatch ◽  
Qi Zhao ◽  
John A. Wright ◽  
Clare E. Bryant ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shear Stress ◽  
Single Cell ◽  
Biofilm Formation ◽  
Fluid Shear Stress ◽  
Cell Membrane Permeability ◽  
Type I ◽  
Fluid Shear ◽  
Content Type ◽  
Type I Fimbriae

ABSTRACT Biofilm formation on abiotic surfaces in the food and medical industry can cause severe contamination and infection, yet how biological and physical factors determine the cellular architecture of early biofilms and the bacterial behavior of the constituent cells remains largely unknown. In this study, we examined the specific role of type I fimbriae in nascent stages of biofilm formation and the response of microcolonies to environmental flow shear at the single-cell resolution. The results show that type I fimbriae are not required for reversible adhesion from plankton, but they are critical for the irreversible adhesion of Escherichia coli strain MG1655 cells that form biofilms on polyethylene terephthalate (PET) surfaces. Besides establishing firm cell surface contact, the irreversible adhesion seems necessary to initiate the proliferation of E. coli on the surface. After the application of shear stress, bacterial retention is dominated by the three-dimensional architecture of colonies, independent of the population size, and the multilayered structure could protect the embedded cells from being insulted by fluid shear, while the cell membrane permeability mainly depends on the biofilm population size and the duration of the shear stress. IMPORTANCE Bacterial biofilms could lead to severe contamination problems in medical devices and food processing equipment. However, biofilms are usually studied at a rough macroscopic level; thus, little is known about how individual bacterium behavior within biofilms and the multicellular architecture are influenced by bacterial appendages (e.g., pili/fimbriae) and environmental factors during early biofilm formation. We applied confocal laser scanning microscopy (CLSM) to visualize Escherichia coli microcolonies at a single-cell resolution. Our findings suggest that type I fimbriae are vital to the initiation of bacterial proliferation on surfaces. We also found that the fluid shear stress affects the biofilm architecture and cell membrane permeability of the constituent bacteria in a different way: the onset of the biofilm is linked with the three-dimensional morphology, while membranes are regulated by the overall population of microcolonies.

Cytoskeletal structure regulates endothelial cell immunogenicity independent of fluid shear stress

2010 ◽  
Vol 298 (2) ◽  
pp. C333-C341 ◽  
Author(s):  
Keri B. Vartanian ◽  
Michelle A. Berny ◽  
Owen J. T. McCarty ◽  
Stephen R. Hanson ◽  
Monica T. Hinds
Keyword(s):  
Gene Expression ◽  
Cardiovascular Disease ◽  
Shear Stress ◽  
Fluid Shear Stress ◽  
Positive Control ◽  
U937 Cells ◽  
Inflammation Markers ◽  
Fluid Shear ◽  
Cytoskeletal Structure ◽  
Cytoskeletal Regulation

The cardiovascular disease atherosclerosis is directly linked to the functions of endothelial cells (ECs), which are affected by fluid shear stress (FSS). High, unidirectional FSS causes EC elongation with aligned cytoskeletal components and nonimmunogenic EC functions that protect against atherosclerosis. In contrast, low, oscillatory FSS is associated with cobblestone-shaped ECs with randomly oriented cytoskeletons and proinflammatory EC functions that promote atherosclerosis. Whether EC shape plays a role in EC immunogenic functions, independent of FSS, has not been previously determined. The goal of this study was to determine the effect of EC elongation and cytoskeletal alignment on the expression of inflammatory genes and functions. With the use of micropatterned lanes, EC elongation and cytoskeletal alignment were achieved in the absence of FSS. EC gene expression of key inflammation markers determined that the elongation and cytoskeletal alignment of micropattern-elongated ECs (MPECs) alone significantly downregulated VCAM-1 while having no effect on E-selectin and ICAM-1. The positive control of FSS-elongated ECs promoted E-selectin and VCAM-1 downregulation and upregulation of ICAM-1. Functionally, monocytic U937 cells formed weaker interactions on the surface of MPECs compared with cobblestone ECs. Interestingly, MPEC expression of the known FSS-dependent transcription factor krüppel-like factor 2 (KLF2), which promotes a nonimmunogenic EC phenotype, was significantly upregulated in MPECs compared with cobblestone ECs. Cytoskeletal regulation of KLF2 expression was shown to be dependent on microtubules. Therefore, the cellular elongation and cytoskeletal alignment of MPECs regulated immunogenic gene expression and functions and may act synergistically with FSS to create an EC surface with reduced inflammatory capability.

Fluid Shear Stress Reduces Simvastatin Induced Adhesion Molecule Expression in Cytokine Activated Endothelial Cells

2009 ◽  
Author(s):  
Joanna Rossi ◽  
Léonie Rouleau ◽  
Jean-Claude Tardif ◽  
Richard L. Leask
Keyword(s):  
Gene Expression ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Adhesion Molecule ◽  
Fluid Shear Stress ◽  
Lipid Lowering ◽  
Adhesion Molecule Expression ◽  
Fluid Shear ◽  
Endothelial Cell Function ◽  
Static Conditions

Although originally designed as inhibitors of cholesterol biosynthesis, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, are now known to also have non-lipid lowering benefits [1]. Statins have been reported to modulate gene expression in endothelial cells, however, the effect of statins on adhesion molecule expression is contradictory. Some studies report a decrease in adhesion molecule mRNA and/or protein after statin treatment [2], while others have shown that statins potentiate the effect of tumor necrosis factor alpha (TNFα) [3]. To the best of our knowledge, the effects of statins on gene expression in cultured endothelial cells has been done in static conditions only and no study has examined the effect of blood flow. This is particularly important since fluid shear stress is a strong regulator of endothelial cell function and phenotype [4]. The purpose of this study was to clarify the effects of statins on vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) expression in endothelial cells by evaluating their biological response under fluid flow.

scholarly journals Latrophilins are essential for endothelial junctional fluid shear stress mechanotransduction

2020 ◽  
Author(s):  
Keiichiro Tanaka ◽  
Andrew Prendergast ◽  
Jared Hintzen ◽  
Abhishek Kumar ◽  
Minhwan Chung ◽  
...  
Keyword(s):  
Shear Stress ◽  
G Proteins ◽  
Fluid Shear Stress ◽  
Affinity Purification ◽  
Cell Junctions ◽  
Heterotrimeric G Proteins ◽  
Fluid Shear ◽  
Vascular Morphogenesis ◽  
Flow Activation

AbstractEndothelial cell (EC) responses to fluid shear stress (FSS) are crucial for vascular development, adult physiology and disease. PECAM1 is an important transducer but earlier events remain poorly understood. We therefore investigated heterotrimeric G proteins in FSS sensing. Knockdown (KD) in ECs of single Gα proteins had little effect but combined depletion of Gαi and Gαq/11 blocked all known PECAM1-dependent responses. Re-expression of Gαi2 and Gαq but not Gαi1 and Gαi3 rescued these effects. Sequence alignment and mutational studies identified that K307 in Gαi2 and Gq/11 (Q306 in Gαi1/3), determines participation in flow signaling. We developed pull-down assays for measuring Gα activation and found that this residue, localized to the GPCR interface, determines activation by FSS. We developed a protocol for affinity purification of GPCRs on activated Gα’s, which identified latrophilins (ADGRLs) as specific upstream interactors for Gαi2 and Gq/11. Depletion of latrophilin-2 blocked EC activation of Gαi2 and Gαq, downstream events in vitro, and flow-dependent vascular morphogenesis in zebrafish embryos. Surprisingly, latrophilin-2 depletion also blocked flow activation of two additional pathways activated at cell-cell junctions, Smad1/5 and Notch1, independently of Gα proteins. Latrophilins are thus central mediators of junctional shear stress mechanotransduction via Gα protein-dependent and -independent mechanisms.

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