Alignment of Integrin Surface Receptors with Z-Discs in Live Cardiomyocytes Revealed with High Resolution AFM Mapping

Mechanical sensing proteins connect with sarcomeric structures, such as the Z-disc, which impacts cardiomyocyte mechanotransduction. The extracellular matrix (ECM) plays a vital role acting as a passive scaffold and signaling network.We used atomic force microscopy (AFM) to map integrin receptor arrangement on adult rat ventricular myocytes (ARVM) to resolve ECM coupling surface receptor alignment with underlying sarcomere structures, particularly the Z-discs. Plated ARVM's were probed by an Asylum MFP-3D AFM with a silicon nitride cantilever (0.1 N/m) and pyramidal tip (radius ∼ 40 nm). Tip-surface adhesion forces were measured in scanning mode through a 10 μm X 2.5 μm (78 nm X 156 nm resolution) region. Bare gold and laminin (10 μg/ml) coated tips were used.Adhesion force maps from bare tip (Fig. 1 bottom) show clear banding patterns that register with features in the bright field image (Fig. 1 top) and have 1.72 μm sarcomere spacing. Peak adhesion forces are generally twice as large for the laminin coating relative to the bare tip, indicative of surface receptor binding. This AFM methodology offers a tool for characterizing a pathway for sarcomere-ECM coupling.View Large Image | View Hi-Res Image | Download PowerPoint Slide