Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 6: Physics of Cells II

BP 6.9: Talk

Monday, March 26, 2012, 17:15–17:30, H 1028

Mechanosensing of Type IV Pilus mediated Force in Epithelial Cells — •Enno Rainer Oldewurtel, Dirk Opitz, and Berenike Maier — Biozentrum, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln

Mechanical stimuli can act as important cues in triggering signalling of cellular functions. The human pathogen Neisseria gonorrhoeae produces thin polymeric cell appendages called type-IV-pili (T4P). Retraction of these T4P can generate remarkably high forces and has been shown to be required for cytoskeletal changes (cortical plaques) in the host cell during infection.

Here, laser tweezers are used with T4P coated beads to mimic the mechanical stimulus of N. gonorrhoeae and to detect the forces required for the response. Cytoskeletal changes are monitored via fluorescent confocal imaging. We demonstrated a rapid cytoskeletal response to force generated by T4P. Both actin-EGFP and ezrin-EGFP accumulate beneath T4P-coated beads when force is applied exceeding controls without force or without pili within minutes.

Investigating possible mechanisms underlying this response we infected epithelial cells with N. gonorrhoeae and observed the distribution of other proteins tagged to fluorescent markers beneath bacterial micro-colonies. Vinculin, a typical focal complex protein, did not accumulate in cortical plaques. When adding RGD peptides in order to decrease a potential interaction between T4P and integrins, the formation of cortical plaques does not appear to be hindered. These results suggest a mechanism differing to the formation focal complexes.