A Dual Protein-mRNA Localization Screen Reveals Compartmentalized Translation and Widespread Co-translational RNA...

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Local translation provides spatial control over gene expression within cells.
• Understanding mRNA localization patterns is crucial for deciphering cellular function and regulation.

Purpose of the Study:

• To identify mRNAs with specific cytoplasmic localizations and local translation.
• To investigate the relationship between mRNA localization, translation, and protein metabolism.
• To characterize novel structures involved in localized translation.

Main Methods:

• Performed a dual protein-mRNA localization screen using single-molecule fluorescence in situ hybridization (smFISH) in 523 human cell lines.
• Utilized GFP-tagged genes for simultaneous protein and mRNA visualization.
• Employed automated classification for mRNA localization patterns and nascent polypeptide imaging.

Main Results:

• Identified 32 mRNAs with specific cytoplasmic localizations, including at cell edges, endosomes, Golgi, nuclear envelope, and centrosomes (cell-cycle-dependent).
• Discovered that mRNA localization often requires ongoing translation, suggesting widespread co-translational RNA targeting.
• Characterized four novel mRNA-containing foci as specialized translation factories, distinct from P-bodies, which regulate nascent protein metabolism, as exemplified by beta-catenin.

Conclusions:

• Widespread co-translational RNA targeting and localized translation occur at diverse subcellular locations.
• Specialized translation factories represent novel cellular compartments that uniquely regulate nascent protein metabolism.
• These findings reveal a fine granular compartmentalization of translation with implications for spatial gene expression control.