Stochastic threshold in cell size control

TL;DR

This paper investigates how stochastic fluctuations in cell size thresholds influence cell division timing, revealing that noise can cause different size control behaviors and emphasizing the role of gene noise in cell cycle regulation.

Contribution

It introduces a stochastic threshold model for cell size control, showing how autocorrelation in thresholds can alter division statistics and unify different control mechanisms.

Findings

Autocorrelation in thresholds can transform sizer to adder or timer behaviors.

Positive autocorrelation drives adder to timer-like statistics.

Negative autocorrelation makes the model more sizer-like.

Abstract

Classic models of cell size control consider cells divide while reaching a threshold, e.g. size, age, or size extension. The molecular basis of the threshold involves multiple layers of regulation as well as gene noises. In this work, we study cell cycle as first-passage problem with stochastic threshold and discover such stochasticity affects the inter-division statistics, which bewilders the criteria to distinguish the types of size control models. The analytic results show the autocorrelation in the threshold can drive a sizer model to the adder-like and even timer-like inter-division statistics, which is supported by simulations. Following the picture that the autocorrelation in the threshold can propagate to the inter-division statistics, we further show that the adder model can be driven to the timer-like one by positive autocorrelated threshold, and even to the sizer-like one when the threshold is negatively autocorrelated. This work highlights the importance to examine gene noise in size control.