Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 6: Poster I

BP 6.8: Poster

Montag, 1. April 2019, 17:30–19:30, Poster B2

Taming the Factor: Upstream dynamics of Circular Dorsal Ruffle (CDR) regulation — •Malte Ohmstede and Hans-Günther Döbereiner — Institut für Biophysik, Universität Bremen

CDRs are actin based, ring-shaped undulations of the dorsal membrane in, among others, fibroblast cells. CDRs are involved in macropinocytosis, a process in cell proliferation and are also a gateway for various pathogens to enter the cell. Stimulation of CDRs is achieved by various growth factors, e.g. Platelet Derived Growth Factor (PDGF), stimulating their corresponding receptor tyrosine kinase (RTK). The RTKs then trigger a signalling cascade resulting in the formation of CDRs and ultimately macropinocytosis, collapsing CDRs into large vesicles which are then transported to the nucleus. Delivery of growth factors in vitro can be done either passively by relying on growth factors of unknown low concentrations contained in FBS or by explicitly adding known concentrations to the medium. Depending on PDGF concentration, a clear difference in CDR shape is observed. Larger concentrations result in CDRs spanning over most of the lammelipodium, whereas low concentrations yield small rings. Upon stimulation of the entire lammelipodium, most RTKs are consumed, resulting in a recovery time needed for the cell to re-express the receptors before being able to be stimulated again. Using a combination of microfluidics and microcontact printing, it is possible to observe medium switching at precise times and without imaging interruption. Thus, cell reaction and recovery times can be precisely measured.