Cell density sensing and size determination
Article first published online: 27 APR 2011
© 2011 The Authors. Development, Growth & Differentiation © 2011 Japanese Society of Developmental Biologists
Development, Growth & Differentiation
Special Issue: SOCIAL AMOEBA AND THE ORIGIN OF MULTICELLULARITY
Volume 53, Issue 4, pages 482–494, May 2011
How to Cite
Gomer, R. H., Jang, W. and Brazill, D. (2011), Cell density sensing and size determination. Development, Growth & Differentiation, 53: 482–494. doi: 10.1111/j.1440-169X.2010.01248.x
- Issue published online: 18 MAY 2011
- Article first published online: 27 APR 2011
- Received 17 November 2010; revised 1 December 2010; accepted 2 December 2010.
- cell density sensing;
- cell number counting;
- quorum sensing;
The social amoeba Dictyostelium discoideum is one of the leading model systems used to study how cells count themselves to determine the number and/or density of cells. In this review, we describe work on three different cell-density sensing systems used by Dictyostelium. The first involves a negative feedback loop in which two secreted signals inhibit cell proliferation during the growth phase. As the cell density increases, the concentrations of the secreted factors concomitantly increase, allowing the cells to sense their density. The two signals act as message authenticators for each other, and the existence of two different signals that require each other for activity may explain why previous efforts to identify autocrine proliferation-inhibiting signals in higher eukaryotes have generally failed. The second system involves a signal made by growing cells that is secreted only when they starve. This then allows cells to sense the density of just the starving cells, and is an example of a mechanism that allows cells in a tissue to sense the density of one specific cell type. The third cell density counting system involves cells in aggregation streams secreting a signal that limits the size of fruiting bodies. Computer simulations predicted, and experiments then showed, that the factor increases random cell motility and decreases cell–cell adhesion to cause streams to break up if there are too many cells in the stream. Together, studies on Dictyostelium cell density counting systems will help elucidate how higher eukaryotes regulate the size and composition of tissues.