Cells process more information by clustering signals
Living cells constantly have to take decisions on the basis of information from their environment. Researchers from FOM Institute AMOLF discovered that the clustering of signals enables cells to process more information. Cellular calculations become more accurate as a result of the clustering and this enables cells to make better decisions, for example about whether they must divide or not. The researchers published their results 25 March in Proceedings of the National Academy of Sciences.
Receiving information
Cells receive information from their environment via receptor proteins on their surface, which detect molecules in the environment. Recent experiments have revealed that these receptors are not randomly spread across the cell surface, but instead occur in clusters of five to ten molecules. The advantage of this clustering, and the origin of this characteristic cluster size, were not clear up until now. Research from the group of professor Pieter Rein ten Wolde has demonstrated that the clustering ensures less noise in the signal and optimisation of the information transfer.
Clustering reduces noise
When receptor proteins detect molecules in the environment, they activate other proteins that send the signal into the cell. This activation is not permanent, however; proteins switch constantly between an active ('on') and an inactive ('off') state. This switching is a major source of noise, which negatively influences the quality of the signal. The researchers discovered that the distribution of proteins in clusters strongly reduces the noise. Instead of all of the proteins switching at once, the molecules now switch at the same time within a cluster, whereas the different clusters switch independently of each other. The cell subsequently averages the activity of the different clusters which yields a reliable signal.
Optimisation of information transfer
To clarify the characteristic cluster size, the researchers applied ideas from the information theory that Claude Shannon developed in 1948 to improve telecommunication. Calculations revealed that there is an optimal cluster size in which the number of bits of information is greatest. This theoretical optimal size turned out to be fice to ten molecules; surprisingly enough that is exactly what was observed in the experiments. This demonstrates that cells cluster molecules to realise cellular calculations more accurately and to optimise information transfer.
Contact
Dr. Andrew Mugler, +31 (0)20 754 73 69
Prof. Pieter-Rein ten Wolde, +31 (0)20 754 72 81
Reference
Andrew Mugler, Filipe Tostevin, en Pieter Rein ten Wolde, Spatial partitioning improves the reliability of biochemical signaling, Proc. Natl. Acad. Sci. USA (Early Edition, 25 maart 2013)