A \u2018dynamic adder model\u2019 for cell size homeostasis in Dictyostelium cells

Masahito Tanaka,Shigehiko Yumura,Toshiko Kitanishi-Yumura

doi:10.1038/s41598-021-92700-3

Masahito Tanaka, Shigehiko Yumura + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-92700-3

Copy DOI

Abstract

After a cell divides into two daughter cells, the total cell surface area of the daughter cells should increase to the original size to maintain cell size homeostasis in a single cell cycle. Previously, three models have been proposed to explain the regulation of cell size homeostasis: sizer, timer, and adder models. Here, we precisely measured the total cell surface area of Dictyostelium cells in a whole cell cycle by using the agar-overlay method, which eliminated the influence of surface membrane reservoirs, such as microvilli and membrane wrinkles. The total cell surface area exponentially increased during interphase, slightly decreased at metaphase, and then increased by approximately 20% during cytokinesis. From the analysis of the added surface area, we concluded that the cell size was regulated by the adder or near-adder model in interphase. This adder model is not caused by a simple cell membrane addition, but is more dynamic due to the rapid cell membrane turnover. We propose a ‘dynamic adder model’ to explain cell size homeostasis in interphase.

Highlights

After a cell divides into two daughter cells, the total cell surface area of the daughter cells should increase to the original size to maintain cell size homeostasis in a single cell cycle
From the analysis of the added surface area, the cell surface area at birth, and the generation time, we found that the cell size homeostasis during interphase of Dictyostelium cells is regulated by the adder or near-adder model
Since Dictyostelium cells grow by phagocytosing bacteria in a natural habitat, cells were observed in the presence of live bacteria (Escherichia coli) under an agar-overlay (Fig. 1A)

Summary

Introduction

After a cell divides into two daughter cells, the total cell surface area of the daughter cells should increase to the original size to maintain cell size homeostasis in a single cell cycle. Cell size homeostasis has been mainly studied in yeasts and bacteria, because their cell shapes are relatively simple, and their size can be measured[4,5,6] Studies of these cells have shown that they regulate the growth rate and the cell cycle in such a way that larger cells at birth divide earlier than smaller ones, and vice v ersa[7,8]. Adder models have been reported for Escherichia coli, Bacillus subtilis, and budding yeast, whose cells divide after a certain amount of cell size (cell volume, cell surface area, among others) is added, independently of their initial size[4,11,12].

Methods

Results

Conclusion