How cells decide under stress

When conditions near a wound — or anywhere else — turn hostile, each cell has to “decide” what to do: migrate, pause, divide. To study such decisions in a system that can be controlled precisely, I joined Peter Swain’s lab in Edinburgh and work with the budding yeast Saccharomyces cerevisiae, looking at how a cell responds when resources run out.

I approach the question from three angles:

• Transcription-factor dynamics — how the timing of nuclear translocation encodes the type and severity of a stress.
• Protein condensates — how liquid–liquid phase separation reorganises the cytoplasm under stress, and whether condensates store or release information.
• Chemoreception in transient environments — a theoretical framework combining Berg–Purcell diffusion limits, boundary homogenisation and transporter kinetics to ask how well a cell can sense nutrients that come and go.

To make this measurable, I built a multi-chamber microfluidic device that images 20 yeast strains in parallel under controlled conditions with single-cell tracking, and screened more than 300 stress-response proteins. Deep-learning tools I developed follow the fate of millions of cells and reveal stress-specific dynamic signatures.

This builds on earlier work with Pascal Hersen’s group showing that severe osmotic compression slows down intracellular signalling, quantitatively explained by molecular crowding — a direct link between soft-matter physics and cell regulation.

Key outputs

• Miermont A., Waharte F., et al. Severe osmotic compression triggers a slowdown of intracellular signaling, which can be explained by molecular crowding. PNAS (2013). doi:10.1073/pnas.1215367110
• El-Daher F., Swain P.S. Theory of chemoreception in a transient environment. In preparation.
• El-Daher F., et al. Stress response in yeast relies on the spatio-temporal dynamics of protein condensation. In preparation.