Emerging of Ultrafine Membraneless Organelles as the Missing Piece of Nanostress: Mechanism of Biogenesis and Implications at Multilevels.

Understanding the interaction between nanomaterials and cellular structures is crucial for nanoparticle applications in biomedicine. We have identified a subtype of stress granules, called nanomaterial-provoked stress granules (NSGs), induced by gold nanorods (AuNRs). These NSGs differ from traditional SGs in their physical properties and biological functions. Uptake of AuNRs causes reactive oxygen species accumulation and protein misfolding in the cell, leading to NSG formation. Physically, NSGs have a gel-like core and a liquid-like shell, influenced positively by HSP70 and negatively by HSP90 and the ubiquitin-proteasome system. AuNRs promote NSG assembly by interacting with G3BP1, reducing the energy needed for liquid-liquid phase separation (LLPS). NSGs impact cellular functions by affecting mRNA surveillance and activating Adenosine 5'-monophosphate (AMP)-activated protein kinase signaling, crucial for a cellular stress response. Our study highlights the role of LLPS in nanomaterial metabolism and suggests NSGs as potential targets for drug delivery strategies, advancing the field of nanomedicine.