Künstliche Signaltransduktion mit Botenstoffen
Final Report Abstract
In spite of the eminent importance of transmembrane signalling in Nature, very few examples of artificial versions have been constructed by chemists. We have therefore embarked on a program aimed at the construction of an entirely artificial model based on the principle of receptor tyrosine kinases. The first funding period has led to the synthesis of a large number of transmembrane units as membrane-spanning bisamphiphiles, which could all be coassembled within unilamellar liposomes. Based on the receptor tyrosine kinase principle, various artificial signal transduction systems were realized, producing either a FRET signal or a second messenger or a fluorescence quenching. In our first subproject, the principle of receptor tyrosine kinases was imitated by two unsymmtrical transmembrane units, which carried on one end a synthetic receptor unit and on the other end a fluorescence donor or acceptor group. Thus external addition of a primary messenger molecule leads to formation of a heterodimeric complex of two transmembrane units which in turn stimulates a strong FRET effect on the opposite intracellular side. The readout can be enhanced and transferred into the visible range by external eosin addition, producing a multi-FRET system. Signalling can thus be detected by the naked eye. The second subproject added the release of a secondary messenger: To this end, a reactive thiol/disulfide pair was introduced at the bottom end of the transmembrane units, while the bisphosphonate headgroups were kept for molecular recognition. Now the complete chain of entirely artificial signal transduction was realized: thus primary messenger docking, signal transmission and secondary messenger release could all be imitated in a single experimental setup. A very promising third system based on intracellular Michael addition with powerful concomitant fluorescence emission has been prepared in parts and should definitely be finished in the future. Ditopic recognition of adrenalin as a natural primary messenger turned out to be difficult. Hence remaining challenges comprise the use of different receptor heads to avoid formation of homodimers, the orientation of all TM units in the membrane with their receptor heads pointing outside, and finally – transition to living cells.
Publications
- “Entirely Artifical Signal Transduction with Adrenaline.” J. Rec. Signal Trans. 2006 (Special Issue: Proceedings of the 10th Swiss Receptor Workshop), 26, 473-485
M. Maue, M. Ellermann, T. Schrader
- “Biamphiphilic Bifunctional Transmembrane Building Blocks for Artificial Signal Transduction.” Synthesis 2008, 2247-2256 (special issue dedicated to RWH)
K. Bernitzki, M. Maue, M. Ellermann, T. Schrader
- “Entirely Artificial Signal Transduction With a Primary Messenger." Angew. Chem. 2009, 48, 8001-8005
K. Bernitzki, M. Maue, T. Schrader
- “Artificial Signal Transduction with a Primary and Secondary Messenger." Chem. Eur. J. 2012, 18, 13412-13417
K. Bernitzki, M. Maue, T. Schrader
(See online at https://doi.org/10.1002/chem.201200623)
