Seminár z kvalitatívnej teórie diferenciálnych rovníc
Seminar on Qualitative Theory of Differential Equations
Štvrtok 25.10.2018 o 14:00, poslucháreň M-223
Pavol Bokes (KAMŠ FMFI UK):
Sustaining sub-Poissonian gene-expression noise in a feedforward regulation model
Abstract:
Cells use various regulatory motifs, including feedforward loops, to control the intrinsic noise
that arises in gene expression at low copy numbers. Here we study one such system,
which is broadly inspired by the interaction between an mRNA molecule
and an antagonistic microRNA molecule encoded by the same gene.
The two reaction species are synchronously produced, individually degraded, and the second
species (microRNA) exerts an antagonistic pressure on the first species (mRNA).
Using linear-noise approximation, we show that the noise in the first species,
which we quantify by the Fano factor, is sub-Poissonian, and exhibits a nonmonotonic
response both to the species lifetime ratio and to the strength of the antagonistic interaction.
Additionally, we use the Chemical Reaction Network Theory to prove that the first species
distribution is Poissonian if the first species is much more stable than the second.
Finally, we identify a special parametric regime, supporting a broad range of behaviour,
in which the distribution can be analytically described in terms of the confluent
hypergeometric limit function. We verify our analysis against large-scale kinetic
Monte Carlo simulations. Our results indicate that, subject to specific physiological
constraints, optimal parameter values can be found within the mRNA--microRNA motif
that can benefit the cell by lowering the gene-expression noise.