C-terminal short arginine/serine repeat sequence-dependent regulation of Y14 (RBM8A) localization

Takanori Tatsuno,Yasuhito Ishigaki

doi:10.1038/s41598-017-18765-1

Takanori Tatsuno, Yasuhito Ishigaki

Open Access

https://doi.org/10.1038/s41598-017-18765-1

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Journal: Scientific Reports	Publication Date: Jan 12, 2018
Citations: 11	License type: open-access

Affiliation: Kanazawa Medical University

Abstract

Y14 (RBM8A) is an RNA recognition motif-containing protein that forms heterodimers with MAGOH and serves as a core factor of the RNA surveillance machinery for the exon junction complex (EJC). The role of the Y14 C-terminal serine/arginine (RS) repeat-containing region, which has been reported to undergo modifications such as phosphorylation and methylation, has not been sufficiently investigated. Thus, we aimed to explore the functional significance of the Y14 C-terminal region. Deletion or dephosphorylation mimic mutants of the C-terminal region showed a shift in localization from the nucleoplasmic region; in addition, the C-terminal RS repeat-containing sequence itself exhibited the potential for nucleolar localization. Additionally, the regulation of Y14 localization by the C-terminal region was further found to be exquisitely controlled by MAGOH binding. Cumulatively, our findings, which demonstrated that Y14 localization is regulated not only by the previously reported N-terminal localization signal but also by the C-terminal RS repeat-containing region through phosphorylation and MAGOH binding to Y14, provide new insights for the mechanism of localization of short RS repeat-containing proteins.

Highlights

The formation of ribonucleoprotein particles (RNPs) is crucial for the regulation of RNA splicing, translation, degradation, transport, and localization
With respect to exon junction complex (EJC) core components, we have especially focused on Y14, which constitutes a 20-kD protein composed of an N-terminal localization signal, C-terminal short RS repeat-containing region, and central RNA recognition motif (RRM) involved in MAGOH binding
We focused on the C-terminal RS repeat-containing sequence of Y14 because it is conserved in vertebrates; in addition, serine residues are phosphorylated in several species, invertebrates such as Drosophila or Caenorhabditis elegans do not have these regions (Supplementary Fig. S1)

Summary

Introduction

The formation of ribonucleoprotein particles (RNPs) is crucial for the regulation of RNA splicing, translation, degradation, transport, and localization. A Y14/MAGOH heterodimer binds eIF4A3 to inhibit its ATPase activity, enforcing the structure of the RNA-protein complex. This trimeric complex, known as pre-EJC, is fundamentally related to splicing. With respect to EJC core components, we have especially focused on Y14, which constitutes a 20-kD protein composed of an N-terminal localization signal, C-terminal short RS repeat-containing region, and central RNA recognition motif (RRM) involved in MAGOH binding. RS repeats of several SR proteins have been reported to assist in localization to nuclear speckles, splicing activation, and protein-protein/protein-RNA interactions[25,26,27] These motifs have been reported to be phosphorylated by the SRPK protein kinase family[28].

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