Probing the Membrane Mechanical Structure of HEK293T Cell by AFM-based Stiffness Tomography

In this study, I established an atomic force microscopy-based method to study the mechanical structure of the membrane of adherent eukaryotic cells. Since both the membrane and the underneath cytoskeletons could be simultaneously measured, I adapt a new analytical method for the force curve analysis. With a progressive truncation-refitting force curve analysis, the distribution of surface stiffness can be calculated. After the fluorescence labeling of sphingolipids or membrane protein, I correlate the stiffness and the molecular distribution by overlapping the fluorescence image with the stiffness distribution. With this method, I studied the membrane on the glycosphingolipid monosialotetrahexosylganglio (GM1) and the membrane around the membrane protein, gamma-aminobutyric acid type A receptor (GABAA receptor), subtype (alpha1)2(beta2)2 gamma2. I observed that both the GM1 and the GABAA receptor, subtype (alpha1)2(beta2)2 gamma2, are partitioned into a stiffer and higher domain than adjacent region.