Protein Translocation Analysis by Automated Image Processing

Olga Domanova, Stefan Borbe, Stefanie Mühlfeld, Ralf Kubitz, Dieter Häussinger, and Thomas Berlage


Biomedical computing, Medical image processing, Topological proteomics


Many dynamic cellular processes are associated with intraand intercellular translocation of proteins. Several proteins are responsible for the active transport across the membrane of liver cells. For example, bile salts are exported from hepatocytes into adjacent canaliculi by transporter proteins embedded in the membrane. Under hyperosmotic conditions they are retrieved into intracellular vesicles and transport is down regulated. The location of these transporters can be explored by fluorescence microscopy. A toponomic analysis of the hepatic transporters may reveal functional information of clinical relevance and serve as an example of other location-regulated processes. An automated method was developed which quantifies the localisation of transporter proteins in a cell. Laser scanning confocal microscopy images were analysed for suitable membrane segments by automatic image processing. Protein distribution profiles across the membrane were obtained and quantified. Rat liver tissue samples incubated under normal and hyperosmotic conditions were compared. The fully automated workflow for the information extraction and statistical evaluation has been elaborated and produces robust results. Slow manual calculation can be substituted by the faster and completely automated method. Furthermore, the new method only uses objective and reproducible criteria. Robustness and stable performance have been shown on various data sets.

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