Elastic properties of the cell surface and trafficking of single AMPA receptors in living hippocampal neurons
Alexandre Yersin 1*, Harald Hirling 1, Sandor Kasas 1, Charles Roduit 1, Karina Kulangara 1, Giovanni Dietler 1, Frank Lafont 1, Stefan Catsicas 1 and Pascal Steiner 1
1 EPFL
* To whom correspondence should be addressed. E-mail: ayersin{at}bio.titech.ac.jp.
Submitted on July 4, 2006
Revised on September 30, 2006
Accepted on 21 February 2007
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Abstract |
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Although various approaches are routinely used to study receptor trafficking, a technology that allows for visualizing trafficking of single receptors at the surface of living cells remains lacking. Here we used atomic force microscope (AFM) to simultaneously probe the topography of living cells, record the elastic properties of their surface and examine the distribution of transfected AMPA-type glutamate receptors (AMPAR). On non-stimulated neurons, AMPARs were located in stiff nanodomains with high elasticity modulus relative to the remaining cell surface. Receptor stimulation with NMDA provoked a permanent disappearance of these stiff nanodomains followed by a decrease (53%) of the number of surface AMPARs. Blocking electrical activity before NMDA stimulation recruited the same number of AMPARs for internalization, preceded by the loss of the stiff nanodomains. However in that case, the stiff nanodomains were recovered and AMPARs were reinserted into the membrane shortly after. Our results show that modulation of receptor distribution is accompanied by changes in the local elastic properties of cell membrane. We postulate therefore that the mechanical environment of a receptor might be critical to determine its specific distribution behavior in response to different stimuli.
Key Words:
AFM, NMDA, elasticity modulus, glutamate
