Membrane Microdomains Regulate Focal Adhesion Size in Bovine Aortic Endothelial Cells

Open Access
Author:
Culver, Margaret Frances
Area of Honors:
Biomedical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Peter J Butler, Thesis Supervisor
  • Peter J Butler, Honors Advisor
  • Justin Lee Brown, Faculty Reader
Keywords:
  • Focal Adhesion
  • Lipid Rafts
  • Non-lipid amphiphiles
Abstract:
Cell membranes were once thought to be functionless, lipid bilayers with little lateral movement within the membrane. We now know that plasma membranes contain different kinds of lipids with varying degrees of hydrophobicity and disorder. It is believed that these lipids arrange themselves into lipid-ordered and lipid-disordered domains, and the height mismatch between these domains causes the ordered domain to sit rest slightly higher than the other lipids, like a “raft”. These “rafts” have been implicated as platforms for cellular signaling. However, their role in mechanotransduction has not been fully elucidated. The goal of this experiment was to perturb the cellular membrane by addition of chemicals which may selectively assemble into certain lipid domains and to quantitatively analyze the focal adhesion dynamics under those conditions. The additives used were benzyl alcohol, Triton-X, and vitamin E. Bovine aortic endothelial cells were transfected with green fluorescent protein tagged to focal adhesion kinase and visualized using total internal reflection microscopy (TIRF-M). The quantitative analysis was completed by the Focal Adhesion Analysis Server. The results showed that Vitamin E and Triton-X both decreased focal adhesion size in the entire cell. Benzyl alcohol increased focal adhesion size in the entire cell. These findings elucidate the role of membrane microdomains in mechanotransduction. The results also showed that benzyl alcohol doubled focal adhesion size at the leading edge of the cells. These findings indicate that benzyl alcohol may play a role in integrin clustering by modifying the cell membrane.