title: Toponomics method for the automated quantification of membrane protein translocation.
abstract: BACKGROUND
  Intra-cellular and inter-cellular protein translocation can be observed by microscopic imaging of tissue sections prepared immunohistochemically. A manual densitometric analysis is time-consuming, subjective and error-prone. An automated quantification is faster, more reproducible, and should yield results comparable to manual evaluation. The automated method presented here was developed on rat liver tissue sections to study the translocation of bile salt transport proteins in hepatocytes. For validation, the cholestatic liver state was compared to the normal biological state.
  
  
  RESULTS
  An automated quantification method was developed to analyze the translocation of membrane proteins and evaluated in comparison to an established manual method. Firstly, regions of interest (membrane fragments) are identified in confocal microscopy images. Further, densitometric intensity profiles are extracted orthogonally to membrane fragments, following the direction from the plasma membrane to cytoplasm. Finally, several different quantitative descriptors were derived from the densitometric profiles and were compared regarding their statistical significance with respect to the transport protein distribution. Stable performance, robustness and reproducibility were tested using several independent experimental datasets. A fully automated workflow for the information extraction and statistical evaluation has been developed and produces robust results.
  
  
  CONCLUSIONS
  New descriptors for the intensity distribution profiles were found to be more discriminative, i.e. more significant, than those used in previous research publications for the translocation quantification. The slow manual calculation can be substituted by the fast and unbiased automated method.
authors.affiliation: Fraunhofer Institute for Applied Information Technology FIT, Schloss Birlinghoven, Sankt Augustin, Germany. olga.domanova@gmail.com
authors.forename: Olga
authors.initials: O
authors.lastname: Domanova
authors.forename: Stefan
authors.initials: S
authors.lastname: Borbe
authors.forename: Stefanie
authors.initials: S
authors.lastname: Mühlfeld
authors.forename: Martin
authors.initials: M
authors.lastname: Becker
authors.forename: Ralf
authors.initials: R
authors.lastname: Kubitz
authors.forename: Dieter
authors.initials: D
authors.lastname: Häussinger
authors.forename: Thomas
authors.initials: T
authors.lastname: Berlage
mesh_terms: D000818:Animals; D001331:Automation; D003720:Densitometry / Q000379:methods*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D015203:Reproducibility of Results
chemical_list: D008565:Membrane Proteins