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Role of cholesterol of membrane microdomain in the uptake of
Francisella tularensis by mouse macrophages |
Pan Xin; Li Guang-Bo; Qu Min; Zhao Zi-Ye; Li Han; Qi Zhong-Tian |
Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, China |
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Abstract The purpose of the current study was to evaluate the role of cholesterol of the membrane microdomain in the uptake of Francisella tularensis ( F. tularensis) LVS by mouse macrophages. A shuttle plasmid, pFNLTP6 gro-gfp, was transformed by electroporation to F. tularensis LVS. Cell cholesterol was stained with Filipin Ⅲ, and caveolin-1 was detected with monoclonal antibody and visualized with Alexa 594 conjugated goat anti-mouse antibodies. F. tularensis LVS infection was analyzed using a fluorescencemicroscope equipped with amotorized Z-focus. In order to evaluate the effect of depletion of the membrane microdomain on F. tularensis entery into macrophages, interference with lipid-rich plasmamembrane through the depletion of cholesterol was performed by methyl-β-cyclodextrin. The cholesterol-binding agent, Filipin III, was used to detect the effect of cholesterol depletion. The results showed that cell cholesterol was co-localized with F. tularensis live vaccine strain in the early uptake stage, and both had close contact with the membrane microdomain-associated components, such as caveolin-1. F. tularensis requires cholesterol-rich membrane microdomains for entry into macrophages. These findings suggest that cholesterol-rich membrane microdomains and caveolin-1 play an important role in F. tularensis early entry into macrophages.
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Received: 05 May 2009
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Corresponding Authors:
Pan Xin; Qi Zhong-Tian
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