Vimentin associated focal adhesion nanostructure characterization

Abstract

Focal adhesions are multiprotein structures that connect cells to the extracellular matrix. They serve as an anchorage site for the cytoskeletal network and play a significant role in mechanosensing and signal transduction, leading to change in cell behavior. The dynamic nature of focal adhesion is crucial to cell motility. The nanoscale view of focal adhesion consists of protein components that are vertically arranged into three distinct layers. The association of actin filaments and microtubules with focal adhesions has been extensively investigated over the years, but the role of vimentin intermediate filaments remains unclear. The loss of directionality in vimentin knock-out fibroblast cells and delayed wound healing in vimentin null mouse models suggest a possible role of vimentin in focal adhesion.

The project confirms the association between vimentin filaments and focal adhesions based on the data collected using super-resolution STED microscopy. The correlation between vimentin and focal adhesion protein vinculin is observed to be the strongest compared to paxillin and pFAK. The absence of vimentin in cells is suspected of having a minor effect on the focal adhesion nanostructure as the degree of correlation between proteins of two layers is inconsistent between wildtype and vimentin knockout HDF cells. However, the study needs further investigation with an isotropic resolution above 20 nm for confirmation. The project successfully obtained correlative STED and SEM images by unroofing cells to investigate the association of focal adhesion with vimentin at the ultrastructural level and requires additional optimizations to produce a quantifiable result.