Atomic force microscopy of microvillous cell surface dynamics at fixed and living alveolar type II cells

Anal Bioanal Chem. 2011 Mar;399(7):2369-78. doi: 10.1007/s00216-010-4407-z. Epub 2010 Nov 30.

Abstract

Scanning probe techniques enable direct imaging of morphology changes associated with cellular processes at life specimen. Here, glutaraldehyde-fixed and living alveolar type II (ATII) cells were investigated by atomic force microscopy (AFM), and the obtained topographical data were correlated with results obtained by scanning electron microscopy (SEM) and confocal microscopy (CM). We show that low-force contact mode AFM at glutaraldehyde-fixed cells provides complementary results to SEM and CM. Both AFM and SEM images reveal fine structures at the surface of fixed cells, which indicate microvilli protrusions. If ATII cells were treated with Ca(2+) channel modulators known to induce massive endocytosis, changes of the cell surface topography became evident by the depletion of microvilli. Low force contact mode AFM imaging at fixed ATII cells revealed a significant reduction of the surface roughness for capsazepine and 2-aminoethoxydiphenyl-borate (CPZ/2-APB)-treated cells compared to untreated control cells (Rc of 99.7 ± 6.8 nm vs. Rc of 71.9 ± 4.6 nm for N = 22), which was confirmed via SEM studies. CM of microvilli marker protein Ezrin revealed a cytoplasmic localization of Ezrin in CPZ/2-APB-treated cells, whereas a submembranous Ezrin localization was observed in control cells. Furthermore, in situ AFM investigations at living ATII cells using low force contact mode imaging revealed an apparent decrease in cell height of 17% during stimulation experiments. We conclude that a dynamic reorganization of the microvillous cell surface occurs in ATII cells at conditions of stimulated endocytosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alveolar Epithelial Cells / drug effects
  • Alveolar Epithelial Cells / metabolism
  • Alveolar Epithelial Cells / ultrastructure*
  • Animals
  • Boron Compounds
  • Calcium
  • Capsaicin / analogs & derivatives
  • Cell Membrane / metabolism*
  • Cell Membrane / ultrastructure*
  • Cells, Cultured
  • Cytoskeletal Proteins / immunology
  • Cytoskeletal Proteins / metabolism
  • Endocytosis
  • Glutaral
  • Imaging, Three-Dimensional
  • Lung / cytology
  • Male
  • Microscopy, Atomic Force / methods*
  • Microscopy, Confocal
  • Microscopy, Electron, Scanning / methods
  • Microvilli / metabolism*
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Boron Compounds
  • Cytoskeletal Proteins
  • ezrin
  • 2-aminoethoxydiphenyl borate
  • capsazepine
  • Capsaicin
  • Calcium
  • Glutaral