ELECTRICAL CONTROL OF CELL POLARIZATION – COELPOCE

In this task we introduce the genetically tracktable organism Budding yeast S. Cerevisiae and use forward genetics to understand these EF effects. To understand the effect of EFs on cell polarity of Budding yeast, we use Microfluidic chambers in which yeast cells grow without net movement in the presence of the EF. We use time-lapse movies to monitor where cells grow to form a bud or to form a mating projection.

Using this assay with candidate screens of genes regulating different cellular modules (pooloarity; membrane charge; membrane potential), provides a complete molecular picture of EF effects in single eukaryotic cells.

We are currently developping Optogenetics tools to manipulate polarity.

Published Papers and Reviews:

1. Campetelli A, Bonazzi D, Minc N. (2012), «Electrochemical regulation of cell polarity and the cytoskeleton« Cytoskeleton (Hoboken), 2012 Jun 26. doi: 10.1002/cm.21047.

2. Minc# N. and Piel# M. (2012) ,«Predicting division plane position and orientation« Trends Cell Biol., 22(4). 193-200.

3. Minc# N. , Burgess, D. and Chang F. (2011), «Influence of cell geometry on division plane positioning« Cell., 144 (3): 414-426. #Corresponding author.

Papers in preparation:

4. Campetelli, Bonazzi, Piel Chang and Minc, “Electrochemical regulation of budding yeast polarity” , In preparation

5. Bonazzi and Minc, “Dissecting the molecular mechanisms of electrotactic effects”, Invited review to be published in 2013


Presentation at conferences:

American Society for Cell biology 2011, Denver, USA (Poster):
Campetelli, Bonazzi, Piel Chang and Minc, “Directing yeast polarity with EF.”

Gordon Research Conference 2012 , Membrane electrochemistry , Italy (Poster):
Campetelli, Bonazzi, Piel Chang and Minc, “Directing yeast polarity with EF.”

EMBO meeting 2012, Single cell physiology, France (Poster):
Bonazzi, Romao, Piel Boudaoud and Minc ,“Symmetry breaking in fission yeast germination”

American Society for Cell biology 2012, Denver, USA (Poster):
Campetelli, Bonazzi, Piel Chang and Minc, “Electrochemical regulation of budding yeast polarity”

Cell polarization describes the ability of a cell to use external and/or internal stimuli to decide where to grow, crawl or divide. There are numerous signals that cells can sense and that may compete with each other in vivo. Extra-cellular signals include chemical gradients, sites of cell adhesion, and electric fields. In this proposal we aim to study the electrical aspects of cell polarization. Endogenous electrical signals emerging from organized ion fluxes surround tissues and cells in all organisms and have been measured in many different instances. These electric fields participate in directing cell polarity during different physiological processes such as wound healing, development and metastasis. During these processes, the electric fields are thought to provide an immediate and precise long distance signal to polarize cells throughout the entire tissue. Similar electrical organizations have also been characterized around single polarized large cells such as developing eggs or pollen tubes. It has been observed for decades that the exogenous application of an electric field, on the same order of magnitude as those measured in vivo, can direct cell polarization, migration and division in diverse cell types ranging from bacteria to neuron and neutrophils. However, both the biophysical and the molecular mechanisms underlying these responses remain poorly understood.
This project proposes a global multidisciplinary approach to unravel the key mechanisms by which cells sense electric fields and use these signals to engineer artificially controllable cells and develop new methodology and devices for biomedical applications in cancer diagnosis. The first goal aims to use the genetic model organisms fission yeast and budding yeast to study in depth the molecular basis of these electric fields effects. The polarity orientation of these cells in the presence of electric fields has been established by the candidate during its postdoctoral research. This goal aims to use a global systems biology approach to set up genome-wide visual screens in these two organisms. This screen involves the use of microfluidic systems to probe the response of hundreds of mutants at the same time. These studies promise to identify key regulators for these effects and provide insights into the mechanisms and pathways linking the physical effects of the electric fields to the identified proteins. A second goal aims to use electric fields to control the position of proteins inside cells. It has been observed in several instances that transmembrane factors that have large and charged extracellular domain can be electrophoresed along plasma membranes in vivo. We will use cloning and targeted mutagenesis, coupled with theoretical models of electrophoresis to optimize the design of transmembrane factors and maximize their electrophoretic response. The ultimate aim of this part is to generate proteins chimera of these membrane factors with any cortical or cytoplasmic proteins to be able to control artificially the position of proteins inside cells. These studies will open new avenues for precisely controlling many aspects underlying cell polarity. The final goal of the project is to study and characterize the directional migration response of cancer invasive cells in electrical fields. Differential migration properties of metastases as compared to normal cells or non-invasive cancer cells will be exploited to devise microfluidic-based systems, allowing for phenotyping and sorting these metastases.