Mechanisms of cell size homeostasis and consequences for proliferation and gene expression
Cesar Augusto Nieto Acuna
Post-Doctoral Researcher
University of Delaware
Abstract: Cells reach size homeostasis controlling their growth and division. The inherent stochasticity of intracellular biochemical reactions introduces variability, or ‘noise’, into these processes. In this talk, we study different techniques to model the stochasticity of cell size control. Our modeling includes exponentially growing bacteria and cells with cell cycle- dependent growth rates as occurs in eukaryotic cells. We present simulation techniques that help us to understand the effects of the cell size regulation on the random variability of the gene product. Next, we show how the noise in cell size control affects fluctuations in the proliferation of single-cell clones. With exponential growth in cell size, clonal size fluctuations show a transient increase, and then eventually decay to zero over time (i.e., clonal sizes become more uniform asymptotically). In contrast, for several forms of nonexponential growth, we find qualitatively different results where clonal size fluctuations monotonically increase over time. We compare the theoretical results with recent experiments. These results characterize the interplay of single-cell size control and population-level clonal proliferation, and explain the broad fluctuations in clonal size seen in recent experiments with barcoded cell lines.
Bio: Cesar Nieto earned a PhD in physics from Los Andes University at Bogota, Colombia (2020). Currently, he is a postdoctoral scholar in Dr. Abhyudai Singh’s lab at the University of Delaware since 2021. He works on the stochastic modeling of biological systems. His current research includes models of cell size control, gene expression regulatory networks, cell proliferation, population dynamics, bacterial persistence and sources and effects of the noise in gene expression.
