A role for Rasputin phosphorylation in the differential formation of stress granules upon cellular stress

In their Cell Reports article (Aguilera-Gomez et al, 2017), the Rabouille group from the Hubrecht Institute shows that, even though the appearance of stress granules is similar between different types of cellular stress, the molecular requirement for their formation depends on the type of cellular stress. Stress granules result from the stress-induced coalescence of RNA binding proteins, translation initiation factors, ribosomal subunits and mRNAs into membrane-less assemblies. They are pro survival as they protect untranslated mRNAs from degradation during stress. The RNA binding protein Rasputin, the Drosophila homologue of mammalian G3BP, is a key driver in this process.

Upon Arsenite treatment, Rasputin needs to be dephosphorylated to mediate stress granule formation. However, upon the stress of amino-acid starvation, Rasputin needs to be phosphorylated and needs to bind Sec16, a key component of endoplasmic reticulum (ER) exit sites, for the formation of stress granules. This shows that upon amino-acid starvation, Sec16 integrates the inhibition of protein translation resulting in stress granule formation and the inhibition of protein transport out of the ER.

Prof. Dr. Catherine Rabouille is group leader at the Hubrecht Institute (KNAW) in Utrecht and professor at the Department of Cell Biology of the University Medical Center Groningen and the University of Groningen. In addition, she is affiliated with the Department of Cell Biology at the University Medical Center Utrecht.

Phospho-Rasputin Stabilization by Sec16 is Required for Stress Granule Formation upon Amino Acid Starvation
Cell Reports 2017