Premium
Spontaneous cell polarization: Feedback control of Cdc42 GTPase breaks cellular symmetry
Author(s) -
Martin Sophie G.
Publication year - 2015
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.201500077
Subject(s) - cdc42 , cell polarity , gtpase , cytoskeleton , symmetry breaking , actin cytoskeleton , microbiology and biotechnology , biophysics , actin , biology , negative feedback , chemistry , physics , cell , biochemistry , quantum mechanics , voltage
Spontaneous polarization without spatial cues, or symmetry breaking, is a fundamental problem of spatial organization in biological systems. This question has been extensively studied using yeast models, which revealed the central role of the small GTPase switch Cdc42. Active Cdc42‐GTP forms a coherent patch at the cell cortex, thought to result from amplification of a small initial stochastic inhomogeneity through positive feedback mechanisms, which induces cell polarization. Here, I review and discuss the mechanisms of Cdc42 activity self‐amplification and dynamic turnover. A robust Cdc42 patch is formed through the combined effects of Cdc42 activity promoting its own activation and active Cdc42‐GTP displaying reduced membrane detachment and lateral diffusion compared to inactive Cdc42‐GDP. I argue the role of the actin cytoskeleton in symmetry breaking is not primarily to transport Cdc42 to the active site. Finally, negative feedback and competition mechanisms serve to control the number of polarization sites.