Inhibition of Axon Regeneration by Liquid-like TIAR-2 Granules

• Published in: Neuron (Cambridge, Mass.) Mass.), 2019-10, Vol.104 (2), p.290-304.e8
• Main Authors: Andrusiak, Matthew G., Sharifnia, Panid, Lyu, Xiaohui, Wang, Zhiping, Dickey, Andrea M., Wu, Zilu, Chisholm, Andrew D., Jin, Yishi
• Format: Article
• Language: English
• Subjects: Animals; axon injury; axon regeneration; Axons - metabolism; Axons - physiology; C. elegans; Caenorhabditis elegans; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Cell Compartmentation; CRISPR; Cytoplasmic Granules; Kinases; liquid-liquid phase separation; LLPS; Nerve Regeneration - physiology; Neurons; prion-like domain; Protein Domains; Proteins; Regeneration; RNA granule; RNA Recognition Motif Proteins - genetics; RNA Recognition Motif Proteins - metabolism; RNA-binding protein; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Serine; stress granule; T-Cell Intracellular Antigen-1 - genetics; T-Cell Intracellular Antigen-1 - metabolism; TIA1; tiar-2; Tyrosine
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2019.07.004

Phase separation into liquid-like compartments is an emerging property of proteins containing prion-like domains (PrLDs), yet the in vivo roles of phase separation remain poorly understood. TIA proteins contain a C-terminal PrLD, and mutations in the PrLD are associated with several diseases. Here, we show that the C. elegans TIAR-2/TIA protein functions cell autonomously to inhibit axon regeneration. TIAR-2 undergoes liquid-liquid phase separation in vitro and forms granules with liquid-like properties in vivo. Axon injury induces a transient increase in TIAR-2 granule number. The PrLD is necessary and sufficient for granule formation and inhibiting regeneration. Tyrosine residues within the PrLD are important for granule formation and inhibition of regeneration. TIAR-2 is also serine phosphorylated in vivo. Non-phosphorylatable TIAR-2 variants do not form granules and are unable to inhibit axon regeneration. Our data demonstrate an in vivo function for phase-separated TIAR-2 and identify features critical for its function in axon regeneration. [Display omitted] •The C. elegans TIA family protein TIAR-2 is an intrinsic inhibitor of axon regeneration•TIAR-2 granules have liquid-like features in vivo and undergo LLPS in vitro•The PrLD of TIAR-2 is essential for granule formation and inhibition of regeneration•Tyr and Ser residues in the PrLD are critical for function and granule formation Andrusiak et al. identify liquid-like granules of TIAR-2 as inhibitory for axon regeneration. Serine and tyrosine residues within the prion-like domain are essential for granule formation and function. This study provides a functional in vivo readout for a phase-separated compartment.