THE EFFECT OF CURVATURE ON PROTEIN LOCALIZATION

Zimberlin, Jessica A., Weiger, Michael C., Cicerone, Marcus T.

National Institute of Standards and Technology, Polymers Division

 

Extracellular matrix [ECM] proteins present complex, well-defined nanofeatures in vivo that are hypothesized to contribute to cell-matrix signaling.  With recent progress in micro- and nano-technology, in vitro experiments culturing cells on micron and nano sized channels, beads, fibers, and posts have proven that biological cells do in fact respond to their surrounding topography.  Various studies of cell growth on these nanofeatures has shown alignment of focal adhesions along the edges of the topographical features, but the exact method though by which cells sense these geometries and why alignment occurs is still unknown.  In general, the lipid bilayer of the cell membrane where through which the focal adhesions connect the ECM to the cytoskeleton inside the cell is resistant to bending and should therefore resist bending over these nanofeatures due to the associated high energetic cost.  This cost has been shown to be actively reduced by specialized membrane-associated proteins that allow for the regions of high curvature found in the generation of intracellular vesicles and in organelles.  We therefore hypothesize that the proteins involved in focal adhesions are recruited to reduce the bending energy the cell membrane experiences as it bends over the topographical features on the surface and that the relative amount of curvature of the cell membrane should therefore dictate the amount of protein localized to the bending.  In this study, we culture MC3T3-E1 osteoblasts on tissue culture polystyrene surfaces [TCPS] that have been sparsely coated with TCPS nanofibers of varying curvatures.  We then determine the relative amount of focal adhesion development on and off of the fibers with respect to fiber curvature.  We expect that this research will provide insights into cell material interactions and will help guide in the development of novel tissue scaffolds.