TDRD3, a novel Tudor domain-containing protein, localizes to cytoplasmic stress granules

Abstract

Our previous work has demonstrated that the Tudor domain of the ‘survival of motor neuron’ protein and the Tudor domain-containing protein 3 (TDRD3) are highly similar and that they both have the ability to interact with arginine-methylated polypeptides. TDRD3 has been identified among genes whose overexpression has a strong predictive value for poor prognosis of estrogen receptor-negative breast cancers, although its precise function remains unknown. TDRD3 is a modular protein, and in addition to its Tudor domain, it harbors a putative nucleic acid recognition motif and a ubiquitin-associated domain. We report here that TDRD3 localizes predominantly to the cytoplasm, where it co-sediments with the fragile X mental retardation protein on actively translating polyribosomes. We also demonstrate that TDRD3 accumulates into stress granules (SGs) in response to various cellular stresses. Strikingly, the Tudor domain of TDRD3 was found to be both required and sufficient for its recruitment to SGs, and the methyl-binding surface in the Tudor domain is important for this process. Pull down experiments identified five novel TDRD3 interacting partners, most of which are potentially methylated RNA-binding proteins. Our findings revealed that two of these proteins, SERPINE1 mRNA-binding protein 1 and DEAD/H box-3 (a gene often deleted in Sertoli-cell-only syndrome), are also novel constituents of cytoplasmic SGs. Taken together, we report the first characterization of TDRD3 and its functional interaction with at least two proteins implicated in human genetic diseases and present evidence supporting a role for arginine methylation in the regulation of SG dynamics.

Localization of SERBP1 in stress granules and nucleoli

“…Interaction of SERBP1 with other SG-incorporated RNA-binding proteins SERBP1 has been reported to localize in cytoplasmic SGs that include other proteins such as the ORF1 protein of the LINE-1 retrotransposon [5] and the Tudor domain-containing protein TDRD3 [4]. In our previous study, we observed the interaction of SERBP1 with asymmetric N G ,N G -dimethylarginine-containing proteins by co-immunoprecipitation [2].…”

“…SERBP1 interacts with the Tudor domain of TDRD3 and co-localizes to cytoplasmic stress granules (SGs) [4]. The SERBP1 protein was also reported to localize in SGs with the ORF1 protein of the LINE-1 retrotransposon [5].…”

mRNP granules

“…For example, components of germ granules, such as Piwi-family argonautes, harbor methylated arginines that help recruit tudor domain-containing proteins. Interfering with this interaction can impair both localization of tudor-domain proteins, and the methylated proteins themselves, 48,49 as well as germ granule assembly. 50 Such interactions also underpin recruitment of tudor-domain proteins to stress granules.…”

SMG6 interacts with the exon junction complex via two conserved EJC-binding motifs (EBMs) required for nonsense-mediated mRNA decay

“…This analysis led to the identification of EBMs in the human proteins RRP12 (Oeffinger et al 2004) and TDRD3 (Tudor domain-containing protein 3) (Goulet et al 2008;Linder et al 2008), the uncharacterized protein C2orf68, and the paralog proteins R3HCC1 (R3H and coiled-coilcontaining protein 1) and GIDRP88 (growth inhibition and differentiation-related protein 88) (Fig. 3C).…”