Measuring the intracellular dew point: phase transitions in cells

21 October 2016

Clifford Brangwynne
Department of Chemical and Biological Engineering
Princeton University


Phase transitions are increasingly recognized as playing an important role in intracellular organization, and its dysfunction in protein aggregation diseases. Here I will discuss our work showing that membrane-less RNA and protein rich organelles, known as RNP bodies, represent condensed liquid phase droplets, which assemble by liquid-liquid phase separation. The nucleolus is one such nuclear RNP body, which is important for cell growth and size homeostasis. Using the reductive cell divisions of early C. elegans embryos, we've shown that a simple phase threshold model explains striking features of the intrinsic coupling of nucleolar assembly to cell size. Moreover, the dynamic nucleolar assembly can be quantitatively understood using a classical theoretical framework based on the Cahn-Hilliard formalism. More recently, we've shown that the internal subcompartments of the nucleolus arise from multi-phase coexistence, with important consequences for sequential RNA processing. I will also discuss how phase transitions can be dynamically controlled within living cells, yielding rich insights into the link between intracellular liquids, gels, and the onset of pathological protein aggregation.

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