Automated podosome identification and characterization in fluorescence microscopy images

Marjolein B M Meddens, Bernd Rieger, Carl G Figdor, Alessandra Cambi*, Koen van den Dries

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Podosomes are cellular adhesion structures involved in matrix degradation and invasion that comprise an actin core and a ring of cytoskeletal adaptor proteins. They are most often identified by staining with phalloidin, which binds F-actin and therefore visualizes the core. However, not only podosomes, but also many other cytoskeletal structures contain actin, which makes podosome segmentation by automated image processing difficult. Here, we have developed a quantitative image analysis algorithm that is optimized to identify podosome cores within a typical sample stained with phalloidin. By sequential local and global thresholding, our analysis identifies up to 76% of podosome cores excluding other F-actin-based structures. Based on the overlap in podosome identifications and quantification of podosome numbers, our algorithm performs equally well compared to three experts. Using our algorithm we show effects of actin polymerization and myosin II inhibition on the actin intensity in both podosome core and associated actin network. Furthermore, by expanding the core segmentations, we reveal a previously unappreciated differential distribution of cytoskeletal adaptor proteins within the podosome ring. These applications illustrate that our algorithm is a valuable tool for rapid and accurate large-scale analysis of podosomes to increase our understanding of these characteristic adhesion structures.

Original languageEnglish
Pages (from-to)180-9
Number of pages10
JournalMicroscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada
Volume19
Issue number1
DOIs
Publication statusPublished - Feb 2013
Externally publishedYes

Keywords

  • Actins/metabolism
  • Automation/methods
  • Cell Surface Extensions
  • Cells, Cultured
  • Dendritic Cells/cytology
  • Humans
  • Image Processing, Computer-Assisted/methods
  • Microscopy, Fluorescence/methods
  • Phalloidine/metabolism
  • Staining and Labeling/methods

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