Shear Flow Increases Insulin Sensitivity To Endothelial Cells Via S-Nitrosation of PTP1B

Abstract The phosphatidylinositol 3-kinase signaling pathway in vascular endothelial cells is important for systemic angiogenesis and glucose metabolism. In this study, we addressed the precise role of the 3-phosphoinositide-dependent protein kinase 1 (PDK1)-regulated signaling network in endothelial cells in vivo, using vascular endothelial PDK1 knockout (VEPDK1KO) mice. Surprisingly, VEPDK1KO mice manifested enhanced glucose tolerance and whole-body insulin sensitivity due to suppression of their hepatic glucose production with no change in either peripheral glucose disposal or even impaired vascular endothelial function at 6 months of age. When mice were fed a standard diet at 6 months of age and a high-fat diet at 3 months of age, hypertrophy of epididymal adipose tissues was inhibited, adiponectin mRNA was significantly increased, and mRNA of MCP1, leptin, and TNFα was decreased in the white adipose tissue of VEPDK1KO mice in comparison with controls. Consequently, both the circulating adiponectin levels and the activity of hepatic AMP-activated protein kinase were significantly increased, subsequently enhancing whole-body insulin sensitivity and energy expenditure with increased hepatic fatty acid oxidation in VEPDK1KO mice. These results provide the first in vivo evidence that lowered angiogenesis through the deletion of PDK1 signaling not only interferes with the growth of adipose tissue but also induces increased energy expenditure due to amelioration of the adipocytokine profile. This demonstrates an unexpected role of PDK1 signaling in endothelial cells on the maintenance of proper glucose homeostasis through the regulation of adipocyte development.

Download Full-text

Integrin VLA-4 enhances sialyl-Lewisx/a-negative melanoma adhesion to and extravasation through the endothelium under low flow conditions

AJP Cell Physiology ◽

10.1152/ajpcell.00245.2008 ◽

2008 ◽

Vol 295 (3) ◽

pp. C701-C707 ◽

Cited By ~ 39

Author(s):

Shile Liang ◽

Cheng Dong

Keyword(s):

Endothelial Cells ◽

Shear Flow ◽

Tumor Cells ◽

Melanoma Cell ◽

Melanoma Cells ◽

Host Cells ◽

High Shear ◽

Sialyl Lewis ◽

Adhesive Interactions ◽

Low Shear

During their passage through the circulatory system, tumor cells undergo extensive interactions with various host cells including endothelial cells. The capacity of tumor cells to form metastasis is related to their ability to interact with and extravasate through endothelial cell layers, which involves multiple adhesive interactions between tumor cells and endothelium (EC). Thus it is essential to identify the adhesive receptors on the endothelial and melanoma surface that mediate those specific adhesive interactions. P-selectin and E-selectin have been reported as adhesion molecules that mediate the cell-cell interaction of endothelial cells and melanoma cells. However, not all melanoma cells express ligands for selectins. In this study, we elucidated the molecular constituents involved in the endothelial adhesion and extravasation of sialyl-Lewisx/a-negative melanoma cell lines under flow in the presence and absence of polymorphonuclear neutrophils (PMNs). Results show the interactions of α4β1(VLA-4) on sialyl-Lewisx/a-negative melanoma cells and vascular adhesion molecule (VCAM-1) on inflamed EC supported melanoma adhesion to and subsequent extravasation through the EC in low shear flow. These findings provide clear evidence for a direct role of the VLA-4/VCAM-1 pathway in melanoma cell adhesion to and extravasation through the vascular endothelium in a shear flow. PMNs facilitated melanoma cell extravasation under both low and high shear conditions via the involvement of distinct molecular mechanisms. In the low shear regime, β2-integrins were sufficient to enhance melanoma cell extravasation, whereas in the high shear regime, selectin ligands and β2-integrins on PMNs were necessary for facilitating the melanoma extravasation process.

Download Full-text

Shear flow-driven actin re-organization induces ICAM-1 nanoclustering on endothelial cells that impact T-cell migration

10.1101/2020.06.29.177816 ◽

2020 ◽

Author(s):

Izabela K. Piechocka ◽

Sarah Keary ◽

Alberto Sosa-Costa ◽

Lukas Lau ◽

Nitin Mohan ◽

...

Keyword(s):

T Cells ◽

Endothelial Cells ◽

Cell Migration ◽

T Cell ◽

Shear Flow ◽

Membrane Receptors ◽

Mechanical Forces ◽

Shear Forces ◽

T Cell Migration ◽

The Impact

ABSTRACTThe leukocyte specific β2-integrin LFA-1, and its ligand ICAM-1 expressed on endothelial cells (ECs), are involved in the arrest, adhesion and transendothelial migration of leukocytes. Although the role of mechanical forces on LFA-1 activation is well established, the impact of forces on its major ligand ICAM-1, has received less attention. Using a parallel-plate flow chamber combined with confocal and super-resolution microscopy, we show that prolonged shear-flow induces a global translocation of ICAM-1 on ECs upstream of flow direction. Interestingly, shear-forces promoted ICAM-1 nanoclustering prior to LFA-1 engagement. This spatial nanoscale organization was driven by actin cytoskeleton re-arrangements induced by shear-force. We further assessed the impact of prolonged shear-stress EC stimulation on T cell migration. T cells adhered to mechanically pre-stimulated ECs developed a more pro-migratory phenotype, migrated faster and exhibited shorter EC interactions than when adhered to non-mechanically stimulated ECs. Together, our results indicate that shear-forces increase the number of ICAM-1/LFA-1 bonds due to ICAM-1 nanoclustering, strengthening adhesion and thereby reducing actin retrograde flow of T-cells, leading to their increased migration speed. Our data also underscores the importance of mechanical forces regulating the spatial organization of cell membrane receptors and their contribution to adhesion regulation, regardless of integrin activation.Summary statementWe show that shear forces promote ICAM-1 spatial re-arrangement and actin-dependent nanoclustering on ECs prior to integrin engagement. This mechanism might be important for firm leukocyte adhesion and migration during the immune response.

Download Full-text

Transmission of Anaplasma phagocytophilum from endothelial cells to peripheral granulocytes in vitro under shear flow conditions

Medical Microbiology and Immunology ◽

10.1007/s00430-015-0387-0 ◽

2015 ◽

Vol 204 (5) ◽

pp. 593-603 ◽

Cited By ~ 3

Author(s):

Jinyong Wang ◽

Viktor Dyachenko ◽

Ulrike G. Munderloh ◽

Reinhard K. Straubinger

Keyword(s):

Endothelial Cells ◽

Shear Flow ◽

Anaplasma Phagocytophilum ◽

Flow Conditions

Download Full-text

Inhibition of Hydrophobic Protein-MediatedCandida albicans Attachment to Endothelial Cells during Physiologic Shear Flow

Infection and Immunity ◽

10.1128/iai.69.5.2815-2820.2001 ◽

2001 ◽

Vol 69 (5) ◽

pp. 2815-2820 ◽

Cited By ~ 33

Author(s):

Pati M. Glee ◽

Jim E. Cutler ◽

Evelyn E. Benson ◽

Robert F. Bargatze ◽

Kevin C. Hazen

Keyword(s):

Endothelial Cells ◽

Shear Flow ◽

Cell Surface ◽

Protective Efficacy ◽

Cell Surface Hydrophobicity ◽

Surface Hydrophobicity ◽

Host Cells ◽

Yeast Cells ◽

Cytokine Activation ◽

Endothelial Monolayers

ABSTRACT Adhesion interactions during hematogenous dissemination ofCandida albicans likely involve a complex array of host and fungal factors. Possible C. albicans factors include changes in cell surface hydrophobicity and exposed antigens that have been shown in static adhesion assays to influence attachment events. We used a novel in vitro shear analysis system to investigate host-pathogen interactions and the role of fungal cell surface hydrophobicity in adhesion events with human endothelial cells under simulated physiologic shear. Endothelial monolayers were grown in capillary tubes and tested with and without interleukin-1β activation in buffered medium containing human serum. Hydrophobic and hydrophilic stationary-phase C. albicans yeast cells were infused into the system under shear flow and found to adhere with widely varying efficiencies. The average number of adherent foci was determined from multiple fields, sampled via video microscopy, between 8 and 12 min after infusion. Hydrophobic C. albicans cells demonstrated significantly more heterotypic binding events (Candida-endothelial cell) and greater homotypic binding events (Candida-Candida) than hydrophilic yeast cells. Cytokine activation of the endothelium significantly increased binding by hydrophobic C. albicans compared to unactivated host cells. Preincubation of hydrophobic yeast cells with a monoclonal antibody against hydrophobic cell wall proteins significantly blocked adhesion interactions with the endothelial monolayers. Because the antibody also blocks C. albicans binding to laminin and fibronectin, results suggest that vascular adhesion events with endothelial cells and exposed extracellular matrix may be blocked during C. albicans dissemination. Future studies will address the protective efficacy of blocking or redirecting blood-borne fungal cells to favor host defense mechanisms.

Download Full-text