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Localization of dysfunctional tight junctions in Salmonella enterica serovar typhimurium-infected epithelial layers
M A Jepson1, H B Schlecht, C B Collares-Buzato
1Cell Imaging Facility and Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom. m.a.jepson@bristol.ac.uk
Abstract:
Infection of polarized MDCK epithelial layers by Salmonella enterica serovar Typhimurium is accompanied by increased tight junction permeability and by contraction of perijunctional actinomyosin. We localized dysfunctional tight junctions in serovar Typhimurium-infected MDCK layers by imaging apical-basolateral intramembrane diffusion of fluorescent lipid and found that loss of the apical-basolateral diffusion barrier (tight junction fence function) was most marked in areas of prominent perijunctional contraction. The protein kinase inhibitor staurosporine prevented perijunctional contraction but did not reverse the effects of serovar Typhimurium on tight junction barrier function. Hence, perijunctional contraction is not required for Salmonella-induced tight junction dysfunction and this epithelial response to infection may be multifactorial.
Insights
Salmonella Typhimurium infection increases epithelial cell layer leakiness by disrupting tight junctions. Perijunctional actinomyosin contraction, while observed, is not the cause of this Salmonella-induced barrier dysfunction.
Area of Science:
- Cell biology
- Microbiology
- Epithelial biology
Background:
- Salmonella enterica serovar Typhimurium infection disrupts epithelial barrier function.
- This disruption is associated with changes in tight junctions and actinomyosin cytoskeleton.
Purpose of the Study:
- To investigate the relationship between Salmonella-induced perijunctional actinomyosin contraction and tight junction dysfunction.
- To determine if preventing contraction can restore tight junction barrier function.
Main Methods:
- Utilized polarized Madin-Darby canine kidney (MDCK) epithelial cell layers.
- Infected layers with Salmonella Typhimurium.
- Imaged apical-basolateral intramembrane diffusion of fluorescent lipid to assess tight junction barrier function.
- Administered staurosporine, a protein kinase inhibitor, to prevent actinomyosin contraction.
Main Results:
- Salmonella Typhimurium infection led to increased tight junction permeability and perijunctional actinomyosin contraction.
- Loss of tight junction fence function was most severe in areas of contraction.
- Staurosporine inhibited contraction but did not reverse Salmonella-induced tight junction dysfunction.
Conclusions:
- Perijunctional actinomyosin contraction is not required for Salmonella-induced tight junction dysfunction.
- Epithelial barrier dysfunction during Salmonella infection is likely multifactorial.