Contact

Dr. Günther Gerisch
Cell Dynamics
Phone:+49 89 8578-2326Fax:+49 89 8578-3885

Max Planck Institute of Biochemistry

Am Klopferspitz 18 D-82152 Martinsried Germany

Henrike Kästele Elisabeth Adebola
Secretaries
Phone:+49 (89) 8578 2326Fax:+49 (89) 8578 3885

Emeritus Group "Cell Dynamics"

Overview of Research

We are working on patterns generated in the membrane and the underlying actin network of single cells. Such patterns are responsible for the polarization of motile eukaryotic cells into a protruding front and a retracting tail, and they are basic to cell division, particle uptake, and chemotaxis (Figure 1). Using fluorescent markers for specific phosphoinositides and for proteins that determine the structure of the actin network in the cell cortex, we image in live cells biochemical changes on the sub-second scale. Examples for patterns related to cell polarity are shown in Figure 2.

<p>Figure 1. Patterns of PIP3 (blue), polymerized actin (red), and filamentous myosin-II in cell polarity, cell division, and particle uptake. Under certain conditions, the same components of the cell membrane and the underlying actin network can be imaged in the form of dynamic wave patterns on the substrate-attached cell surface. From Gerisch et al., BMC Cell Biol. 2011, 12:42</p>

Figure 1. Patterns of PIP3 (blue), polymerized actin (red), and filamentous myosin-II in cell polarity, cell division, and particle uptake. Under certain conditions, the same components of the cell membrane and the underlying actin network can be imaged in the form of dynamic wave patterns on the substrate-attached cell surface. From Gerisch et al., BMC Cell Biol. 2011, 12:42

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<p>Figure 2. Actin waves (shown in red) separate two territories on the substrate-attached surface. These territories are distinguished by signaling lipids and GTPases on the membrane, and by proteins that regulate the structure of the actin network (shown in green). Panels on top display fluorescence images, panels below scans of fluorescence intensities along a cross-section through the patterns. From Gerisch et al., BMC Cell Biol. 2011, 12:42</p>

Figure 2. Actin waves (shown in red) separate two territories on the substrate-attached surface. These territories are distinguished by signaling lipids and GTPases on the membrane, and by proteins that regulate the structure of the actin network (shown in green). Panels on top display fluorescence images, panels below scans of fluorescence intensities along a cross-section through the patterns. From Gerisch et al., BMC Cell Biol. 2011, 12:42

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Changes in the organization of the actin network are linked to the up and down of phosphatidyl-inositol (3,4,5)-tris-phosphate (PIP3) in the membrane. PIP3 is synthesized by PI3-kinases and degraded primarily by PI3-phosphatases. One of these phosphatases is the tumor suppressor PTEN. The activity of both enzymes is regulated by their shuttling between the cytoplasmic pool and specific sites on the plasma membrane. The dynamics of PIP3 and PTEN patterns is illustrated in Movie 1.

An example of the dynamic interplay of PIP3 and actin in response to an external signal is provided by the uptake of particles with a complex shape (Movie 2). Cells have three options to handle a bi-lobed particle. They switch between attempts to engulf the entire particle, to cut it into pieces along its furrow or, if the particle is too big, to give up and release the particle (Figure 3).

<p>Figure 3:</p>
<p>How a Phagocyte Handles a Particle of Complex Shape</p>

Figure 3:

How a Phagocyte Handles a Particle of Complex Shape

 

 
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