Pseudovacuoles--immobilized by high-pressure freezing--are associated with blebbing in walker carcinosarcoma cells

Vanhecke, D; Bellmann, R; Baum, O; Graber, W; Eggli, P; Keller, H; Studer, D (2008). Pseudovacuoles--immobilized by high-pressure freezing--are associated with blebbing in walker carcinosarcoma cells. Journal of microscopy, 230(Pt 2), pp. 253-62. Oxford: Wiley-Blackwell 10.1111/j.1365-2818.2008.01982.x

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By applying high pressure freezing and freeze-substitution, we observed large inclusions of homogeneous appearance in the front of locomoting Walker carcinosarcoma cells that have not been described earlier. Live cell imaging revealed that these inclusions were poor in lipids and nucleic acids but had a high lysine (and hence protein) content. Usually one such structure 2-5 mum in size was present at the front of motile Walker cells, predominantly in the immediate vicinity of newly forming blebs. By correlating the lysine-rich areas in fixed and embedded cells with electron microscopic pictures, inclusions could be assigned to confined, faintly stained cytoplasmic areas that lacked a surrounding membrane; they were therefore called pseudovacuoles. After high-pressure freezing and freeze substitution, pseudovacuoles appeared to be filled with 20 nm large electron-transparent patches surrounded by 12 and 15 nm large particles. The heat shock protein Hsp90 was identified by peptide sequencing as a major fluorescent band on SDS-PAGE of lysine-labelled Walker cell extracts. By immunofluorescence, Hsp90 was found to be enriched in pseudovacuoles. Colocalization of the lysine with a potassium-specific dye in living cells revealed that pseudovacuoles act as K+ stores in the vicinity of forming blebs. We propose that pseudovacuoles might support blebbing by locally regulating the intracellular hydrostatic pressure.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy

UniBE Contributor:

Vanhecke, Dimitri; Baum, Oliver; Graber, Werner Adrian and Studer, Daniel Franz










Factscience Import

Date Deposited:

04 Oct 2013 15:03

Last Modified:

04 May 2014 23:19

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URI: (FactScience: 108694)

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