On the mechanisms governing plasma membrane organization - a STED-FCS investigation

by Débora Machado Andrade
Doctoral thesis
Date of Examination:2014-01-06
Date of issue:2014-06-04
Advisor:Prof. Dr. Stefan Hell
Referee:Prof. Dr. Jörg Enderlein
Referee:Prof. Dr. Erwin Neher
Persistent Address: http://dx.doi.org/10.53846/goediss-4527

 

 

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Abstract

English

The plasma membrane is the barrier which localizes and separates life's processes from their external environment. Long described as a free standing two-dimensional fluid mosaic, the organization of the plasma membrane remains elusive. Currently, the most prominent models proposed for its organization lack a consistent body of evidence for their support. Here, we present the first validation of one of these hypotheses: the picket fence model. Using the STED-FCS technique, we demonstrate that cortical actin networks compartmentalize the diffusion of lipids in the plasma membrane of cells. Interestingly, our results further indicate that the Arp2/3 complex is a major regulator of the cortical actin networks, since inhibiting Arp2/3 leads to specific suppression of compartmentalized diffusion of lipids. Furthermore, the extrusion of the actin cortex promoted by the introduction of myelin basic protein networks into cells causes lipid diffusion to be modulated by these networks instead. Conclusively, we have elucidated one of the pivotal mechanisms governing the "fluidity" of the plasma membrane mosaic.
Keywords: STED-FCS; plasma membrane organization; lipid diffusion; cortical actin cytoskeleton
 
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