Dominant Vinculin Binding Angle in Podosomes Revealed by High Resolution Optical Microscopy
in: Biophysical Journal (2011)
Podosomes are dynamic actin-rich cell-matrix adhesion sites of migrating and invasive cells such as macrophages and osteoclasts, and are receiving increasing attention due to their possible involvement in physiological events such as monocyte extravasation and tissue transmigration, as well as pathological conditions such as atherosclerosis, osteoporosis and cancer metastasis. These structures were examined using three different fluorescence microscopy techniques which provide resolution below the diffraction limit: structured illumination microscopy, stimulated emission depletion microscopy and stochastic optical reconstruction microscopy have been used. In high resolution images, it is clearly visible that each podosome consists of an actin core surrounded by a protein-enriched ring, supporting the existing podosome model. However, these rings are polygonal structures rather than smooth circles. An analysis of the binding angles at corners reveals vinculin to have a dominant binding angle of around 115 degrees.