How do mRNAs deal with stress?

Two hallmarks of the integrated stress response of cells are the inhibition of translation and the formation of stress granules (SGs) and processing bodies (PBs). However, it is not well understood how both processes are coupled. In a study published in Molecular Cell, researchers from the Chao group applied single-molecule RNA imaging to study the interactions of mRNAs with SGs and PBs, and found out that the generally accepted assumptions about the function of granules need to be revised. SGs and PBs are membraneless organelles made up of RNA and proteins that assemble during cellular stress. Since it is also well known that translation is inhibited during stress, it is tempting to consider that mRNAs go into these organelles during stress in order to regulate translation and mRNA decay. However, these models have never been proven, mostly because the experimental techniques had not been available. The FMI's Chao lab does have the know-how to image mRNAs! Johannes Wilbertz, a former PhD student in the lab, wanted to make use of such imaging techniques to test the current models regarding the functional interactions between mRNA and granules during stress.