Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 18: Membranes and vesicles I (joint BP/CPP)

BP 18.7: Talk

Tuesday, March 17, 2015, 11:30–11:45, H 1028

No spatial spreading of chemotactic signaling in amoeboid cells upon receptor stimulation — •Matthias Gerhardt, Michael Walz, and Carsten Beta — Institut für Physik und Astronomie, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany

Recently we have shown that in chemotactic Dictyostelium discoideum cells stimulation of a confined membrane region with cAMP leads to confined signaling of PIP3, PTEN, and filamentous actin. A consequence of this observation is that cAMP stimuli cannot trigger spatial spreading of intracellular signaling. However, in the absence of an extracellular cAMP stimulus, components of the signal transduction system where observed to form traveling waves that show all hallmarks of an excitable system. This excitable system is characterized by PIP3-rich membrane regions circumscribed by actin segments propagating together as a composite wave across the substrate attached membrane of a Dictyostelium cell. Since cAMP stimulation causes depletion of such waves, we concluded there must be an intracellular switch, which determines whether the signal transduction is excitable or not. Since earlier observations show that a [betagamma]G knockout remarkably enhances PI3K activity, we conjecture that the PI3K is a suitable candidate to take on the role of an intracellular switch which controls excitability.