Positioning of integrin β1, caveolin‐1 and focal adhesion kinase on the adhered membrane of spreading cells

Abstract

We have investigated the relationship between the spreading of anchorage-dependent cells and the surface-density distribution of plasma membrane adhesion proteins. The surface positioning and density of integrin β1, caveolin-1 (cav-1), the phosphorylated caveolin-1 (p-cav-1) and the focal adhesion kinase (FAK) located on the adhering cell membrane (ACM) of HUVEC cells was studied. Imaging with TIRF microscopy was used, which enabled us to observe a few-nanometers-thin section of the cell above the plasma membrane in combination with image-based analyses. Integrin β1 and cav-1 have spatial interdependence on the ACM. Cells treated with substances that act on cell spreading caused changes in the size of the ACM area, as well as a redistribution of several proteins under investigation. Changes to the ACM area correlated positively with those to the surface density of the cav-1. The high integrin β1 and the low cav-1 surface density, and vice versa, following the treatments show that the presence of one of them not only spatially excludes, but also reduces, the occurrence of the other protein on the ACM, which indicates a regulative mechanism between integrin β1 and cav-1.

Low-Intensity Pulsed Ultrasound Enhances Angiogenesis and Ameliorates Left Ventricular Dysfunction in a Mouse Model of Acute Myocardial Infarction

“…These molecules are also known to play key roles in cell proliferation and angiogenesis induced by mechanical stimuli (eg, shear stress) on the surface of vascular endothelial cells. 15,[19][20][21][22]24 …”

“…15 Caveolins have been shown to bind to a variety of proteins involved in signaling pathways, such as G-protein subunits, tyrosine kinases, nitric oxide synthase, small guanosine triphosphatases, and growth factor receptors. [17][18][19][20] Caveolar membranes are also enriched in cholesterol, glycosphingolipids, and signaling enzymes, such as Src kinase. 21 In addition, caveolae are reported to respond to cell stretch and to contribute to stretch-induced signaling.…”

“…[23][24][25] Although caveolin-1 has no extracellular component, caveolin-1 may play an important role in sensing mechanical stress or the distortion of the extracellular membranes through interaction with β1-integrin. 19,20,26,27 In the present study, we aimed to demonstrate whether the LIPUS ameliorates post-MI LV remodeling and if so, to elucidate the underlying molecular mechanisms involved in the beneficial effects of the LIPUS.…”

Therapeutic Angiogenesis with Sound Waves

“…[55][56][57] Although caveolin-1 has no extracellular component, it plays an important role in sensing mechanical stress or the distortion of the extracellular membranes through interaction with β 1integrin. 51,52,[58][59][60] In cultured cell experiments, the degree of the LIPUS-induced upregulation of mRNA was higher in HUVECs than in human cardiomyocytes, suggesting that vascular endothelial cells may be the main player for the LIPUS-induced angiogenesis. 45) Microarray analysis showed that not only the VEGF signaling pathway but also the focal adhesion pathway were significantly affected by LIPUS.…”

“…47) Caveolins bind to a variety of proteins involved in the signaling pathways such as G-protein subunits, tyrosine kinases, NO synthase, small GTPases, and growth factor receptors. [49][50][51][52] Caveolar membranes are also enriched in cholesterol, glycosphingolipids, and signaling enzymes such as Src kinase. 53) In addition, caveolae are reported to respond to cell stretch, thus contributing to stretchinduced signaling.…”