Dual localization of the RNA binding protein CUGBP-1 to stress granule and perinucleolar compartment

The mRNA-binding protein CUGBP-1 is a multi-faceted factor, involved in a wide range of biological processes including splicing, translation initiation and mRNA degradation. Here we show that CUGBP-1 is a novel constituent of stress granule (SG), the translational silencing machinery assembled in response to environmental stress. CUGBP-1 was rapidly routed to SGs upon exposure to a variety of environmental stress, and actively shuttles between the nucleus and SGs. The linker domain located between the second and third RNA recognition motifs (RRMs) was found to be essential for the recruitment of CUGBP-1 to SGs. Importantly, we discovered that the linker domain is also required to direct CUGBP-1 to another subcellular structure, perinucleolar compartment (PNC). These results demonstrate the dynamic behavior of CUGBP-1 during stress response and that the linker region, in concert with RRMs, plays a significant role in defining its subcellular localization and dynamics.