Intracellular compartments are necessary for the regulation of many biochemical
processes that ensure cell survival, growth and proliferation.
Compartmentalisation is commonly achieved in organelles with defined lipid
membranes, such as mitochondria, endoplasmic reticulum or the Golgi
apparatus. While these organelles are responsible for many localised
biochemical processes, recent evidence points to another class of compartments
that lack membrane boundaries . The structure and content of these bodies
depends on their function and subcellular localisation, but they mainly
incorporate proteins and RNA. Examples of these ribonucleoprotein bodies
(RNPBs) include eukaryotic RNA processing bodies (P-bodies) and stress
granules (SGs) . While most of these structures have been widely studied for
their capacity to bind, store and process mRNAs under different conditions, their
biological functions and physical properties are poorly understood. Recent
intriguing data suggest that liquid-liquid phase separation (LLPS) represents an
important mechanism seeding the formation and defining the function of RNPBs.
In this review, we discuss how LLPS is transforming our ideas about the
biological functions of SGs and P-bodies and their link to diseases.