Information processing by simple molecular motifs and susceptibility to noise.
Biological organisms rely on their ability to sense and respond appropriately to their environment. The molecular mechanisms that facilitate these essential processes are however subject to a range of random effects and stochastic processes, which jointly affect the reliability of information transmission between receptors and, for example, the physiological downstream response. Information is mathematically defined in terms of the entropy; and the extent of information flowing across an information channel or signalling system is typically measured by the 'mutual information', or the reduction in the uncertainty about the output once the input signal is known. Here, we quantify how extrinsic and intrinsic noise affects the transmission of simple signals along simple motifs of molecular interaction networks. Even for very simple systems, the effects of the different sources of variability alone and in combination can give rise to bewildering complexity. In particular, extrinsic variability is apt to generate 'apparent' information that can, in extreme cases, mask the actual information that for a single system would flow between the different molecular components making up cellular signalling pathways. We show how this artificial inflation in apparent information arises and how the effects of different types of noise alone and in combination can be understood.
Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Biosciences, Imperial College London, South Kensington, London SW7 2AZ, UK.
Siobhan S
SS
Mc Mahon
Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Biosciences, Imperial College London, South Kensington, London SW7 2AZ, UK.
Oleg
O
Lenive
Department of Statistics, University of Oxford, Oxford OX1 3TG, UK.
Sarah
S
Filippi
Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Biosciences, Imperial College London, South Kensington, London SW7 2AZ, UK Institute of Chemical Biology, Imperial College London, South Kensington, London SW7 2AZ, UK m.stumpf@imperial.ac.uk.
Michael P H
MP
Stumpf
D008962:Models, Theoretical
extrinsic noise; gene expression; intrinsic noise; mutual information; signal transduction