G3BP isoforms differentially affect stress granule assembly and gene expression during cellular stress

Area of Science:

• Cell Biology
• Molecular Biology
• Genomics

Background:

• Stress granules (SGs) are dynamic cellular structures formed during stress.
• RNA-binding proteins, particularly G3BPs, are crucial for SG assembly.
• The specific roles of G3BP paralogues in SG formation and gene regulation remain unclear.

Purpose of the Study:

• To investigate the functional importance of specific residues in G3BP proteins for SG assembly.
• To elucidate the contribution of different G3BP paralogues to gene expression changes during cellular stress.
• To understand the role of G3BP-mediated protein interactions in the integrated stress response (ISR).

Main Methods:

• Site-directed mutagenesis to create G3BP V11A mutant.
• Total RNA sequencing and ribosome profiling.
• Analysis of G3BP paralogue function under endoplasmic reticulum (ER) stress.

Main Results:

• A conserved residue (V11) in G3BP is critical for G3BP-Caprin-1 complex formation and SG assembly.
• The G3BP V11A mutation alters mRNA levels and ribosome engagement during the ISR.
• G3BP2B demonstrates a preferential role in SG formation and mRNA expression changes under ER stress.

Conclusions:

• Perturbing G3BP protein-protein interactions impacts SG assembly and gene expression during the ISR.
• G3BP paralogues exhibit differential regulation of gene expression under ER stress.
• This study provides insights into the complex mechanisms governing cellular stress responses and gene regulation.