Electrochemical regulation of budding yeast polarity.

Armin Haupt,Daria Bonazzi,Alexis Campetelli,Fred Chang,Nicolas Minc,Matthieu Piel,Mark D Rose

doi:10.1371/journal.pbio.1002029

Abstract

Author SummaryThe ability of cells to orient towards spatial cues is critical for processes such as migration, wound healing, and development. Although the role of electrochemical signals is well characterized in processes such as neuronal signaling, their function in cell polarity is much less understood or appreciated. Application of exogenous electric fields can direct cell polarization in many cell types, and electric fields of similar magnitude surround cells and tissues naturally. However, the significance and mechanism of these responses remain poorly understood. Here, we introduce budding yeast (Saccharomyces cerevisiae) as a powerful model system to study electrochemical regulation of cell polarity. We show that application of electric fields causes budding yeast to polarize in particular directions. We begin to identify key proteins involved in this response, which implicate an electrochemical pathway involving membrane potential, membrane charge, and an ion channel, which ultimately regulate the central polarity factor Cdc42p. These key proteins are not only needed for response to electric fields, but also contribute to cell polarity more generally. To test whether a change in membrane potential is sufficient to control cell polarization, we introduce a light-sensitive ion channel into yeast and show that we can now control the site of polarization simply by using a focused laser beam. Thus, our study shows that electrochemical regulation is an integral component of cell polarity pathways.

Highlights

Cell polarization arises from the asymmetric accumulation of cellular components near a region of the plasma membrane
To test whether a change in membrane potential is sufficient to control cell polarization, we introduce a light-sensitive ion channel into yeast and show that we can control the site of polarization by using a focused laser beam
Our results demonstrate the importance of electrochemical signaling in cell polarity and begin to define mechanistically how they contribute to polarized cell growth

Summary

Introduction

Cell polarization arises from the asymmetric accumulation of cellular components near a region of the plasma membrane. Recent studies identifying certain ion transporters in regulating processes such as cell migration and polarized cell growth indicate potential roles of local pH, ion fluxes, and membrane potentials at the plasma membrane [2,3,4,5,6,7,8]. The physiological relevance of endogenous EFs has been demonstrated in fungal infection [17], immune cell response [18], wound healing, regeneration, and development [6,10,19,20] These findings have led to the proposal that in addition to responding to chemical and mechanical signals, cells may be responding to endogenous electrotactic signals to guide cell polarization [20]. The response of cells to exogenous EFs provides a powerful tool to study electrochemical elements in cell polarization

Methods

Results

Discussion

Conclusion