The Acetylation of Lysine-376 of G3BP1 Regulates RNA Binding and Stress Granule Dynamics

ABSTRACT

Stress granules (SGs) are ribonucleoprotein aggregates that form in response to stress conditions. The regulation of SG dynamics is not fully understood. Permanent pathological SG-like structures were reported in neurodegenerative diseases such as amyotrophic lateral sclerosis. The Ras GTPase-activating protein-binding protein G3BP1 is a central regulator of SG dynamics. We found that the lysine 376 residue (K376) of G3BP1, which is in the RRM RNA binding domain, was acetylated. Consequently, G3BP1 RNA binding was impaired by K376 acetylation. In addition, the acetylation-mimicking mutation K376Q impaired the RNA-dependent interaction of G3BP1 with poly(A)-binding protein 1 (PABP1), but its RNA-independent interactions with caprin-1 and USP10 were little affected. The formation of G3BP1 SGs depended on G3BP1 RNA binding; thus, replacement of endogenous G3BP1 with the K376Q mutant or the RNA binding-deficient F380L/F382L mutant interfered with SG formation. Significant G3BP1 K376 acetylation was detected during SG resolution, and K376-acetylated G3BP1 was seen outside SGs. G3BP1 acetylation is regulated by histone deacetylase 6 (HDAC6) and CBP/p300. Our data suggest that the acetylation of G3BP1 facilitates the disassembly of SGs, offering a potential avenue to mitigate hyperactive stress responses under pathological conditions.

KEYWORDS:

• acetylation
• CBP/p300
• G3BP1
• HDAC6
• stress granule
• stress proteins
• stress response

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at https://doi.org/10.1128/MCB.00052-19.

ACKNOWLEDGMENTS

We thank Sidney Whiteheart (College of Medicine, University of Kentucky) and Scott Conklin (Pocono Rabbit Farm and Laboratory) for guidance on raising and purifying antibodies, Sabire Ozcan (College of Medicine, University of Kentucky) for her help with quantitative PCR and ELISA, and James Geddes (College of Medicine, University of Kentucky) and Chunaram Choudhary (Faculty of Health and Medical Sciences, University of Copenhagen) for helpful discussions.

This work was funded in part by NIH grant R01 NS077284, MDA grant MDA352743, and Department of Veteran Affairs MERIT award I01 BX002149 (to H.Z.), as well as NIH grant R21 NS095299, American Cancer Society grant IRG 85-001-25, and a Research Support Grant from the Office of the Vice President for Research of the University of Kentucky (to J.G.).

J.G. and H.Z. conceived and planned the experiments. J.G., J.C., D.-Y.N., L.T., and K.R.B carried out the experiments. J.G., J.C., L.T., and H.Z. contributed to the analysis and interpretation of the results. J.G. and H.Z. wrote and edited the manuscript. All authors provided critical feedback on the manuscript.

We have no conflicts of interest to declare relevant to this study.