Endothelial cell-extracellular matrix adhesion is mediated by focal contacts and vimentin-associated matrix adhesions (VMAs) at the basal cell surface where the cytoskeleton is linked to heterodimeric clusters of a/p integrin proteins. Heterodimeric integrin pairing appears to convey functional diversity. Focal contacts are not only mechanical anchors but also participate in cell-matrix signaling. Along with microfilaments, vimentin IF can also insert into focal contacts composed of a6p4 laminin binding integrins in microvascular endothelial cells. Bone marrow microvascular cells are attached to the basement membrane via avP3 integrin-containing vimentin-associated matrix adhesions. Vimentin IFs are likely to have a structural/functional role in EC focal contact organization. Vimentin IFs appear to stabilize and regulate cell-matrix adhesions since VMAs became larger, greater in number, and showed increased association with vimentin IFs in ECs subjected to hemodynamic shear stress or flow. Functionality of IF attachment to focal contacts has been further demonstrated by the reduction of the size of VMAs in ECs with reduced vimentin IFs by means of vimentin-silencing RNA. These vimentin knockdown cells display drastically reduced adhesion under physiological flow rates. Vimentin IFs in endothelial cells both stabilize and regulate the size of FCs, which allows regulation of cell-matrix adhesion and resistance to flow .
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.