Ras Homolog Enriched in Brain Protein Reverses Amyloid Beta-Induced Escape of Inflammatory Cytokine mRNAs From Immunoisolated RNA Processing Bodies of Glioblastoma Cells.

Post-transcriptional regulation by RNA processing bodies, also known as P-bodies (PBs), is vital for mRNA translation, localization, and stability in various animal cells, including neurons and glial cells. PBs enable spatial control of protein synthesis, influencing differentiation and synaptic function. Understanding mRNA storage within PBs is essential for identifying the mechanism controlling post-transcriptional gene expression in brain cells and for understanding its role in neurodegenerative diseases. We developed a detergent-based method to isolate phase-separated P-bodies, free of cytosolic factors and RNAs, enabling us to analyze the mRNA content of PBs under different cellular or experimental conditions. Using neuronal (NGF-differentiated PC12) and glial cell (C6 glioblastoma) models, we studied how Aβ1-42-oligomers affect PB-associated mRNAs. In neuronal cells, exposure to Aβ1-42-oligomers disrupted the release of mRNAs associated with neuronal differentiation, impairing their translation. Whereas astroglial cells showed increased levels of cytoplasmic pro-inflammatory cytokine mRNAs after amyloid treatment, these mRNAs escaped from RNA processing bodies, leading to enhanced translation. Interestingly, ectopic expression of Ras Homolog Enriched in Brain (Rheb) protein, known to influence miRNA reactivation, helped restore the localization of inflammatory cytokine mRNAs IL-6 and IL-1β to PBs and lowered their expression in Rheb-activated astroglia. Our findings suggest that targeting cytokine mRNAs to PBs could be a potential strategy to manage inflammation in activated astroglia in neurodegenerative diseases. At the same time, PB isolation from detergent-permeabilized cells can be an effective, simplified method for studying PB-RNA dynamics in eukaryotic cells.