Understanding the proliferation-quiescence switch using quantitative cellular biochemistry

Cells grow and divide to produce new cells in a regulated process known as the cell cycle. Most cells in adults are non-dividing or quiescent. The ability to switch reversibly from a quiescent state to a dividing state is essential for renewing and repairing old or damaged tissues. The cell cycle has four phases: gap 1 (G1), synthesis (where new DNA is made), gap 2 (G2) and mitosis or cell division. Cells can enter or exit the cycle during the gap phases. However, what happens in these phases is poorly understood, largely because we lack ways of defining progress through these phases. Progress through the cell cycle is dependent on the amount of specific proteins at different times.

I aim to understand what happens to all of the different proteins in the cell when they enter and progress through G1. I have developed a sensitive way of separating cells into different cell cycle stages and by measuring how much of each regulatory protein is present. I can test whether our current ideas of how the process is controlled are correct or if we are missing important pieces of the puzzle.