Journal Article

Active nuclear import and passive nuclear export are the primary determinants of TDP-43 localization

Chook, Yuh Min, Thomas, Philip J., Fung, Ho Yee Joyce, Li, Ying C., Pinarbasi, Emile S., Cağatay, Tolga

2018

Overview

ALS (Amyotrophic Lateral Sclerosis) is a neurodegenerative disease characterized by the redistribution of the RNA binding protein TDP-43 in affected neurons: from predominantly nuclear to aggregated in the cytosol. However, the determinants of TDP-43 localization and the cellular insults that promote redistribution are incompletely understood. Here, we show that the putative Nuclear Export Signal (NES) is not required for nuclear egress of TDP-43. Moreover, when the TDP-43 domain which contains the putative NES is fused to a reporter protein, YFP, the presence of the NES is not sufficient to mediate nuclear exclusion of the fusion protein. We find that the previously studied “∆NES” mutant, in which conserved hydrophobic residues are mutated to alanines, disrupts both solubility and splicing function. We further show that nuclear export of TDP-43 is independent of the exportin XPO1. Finally, we provide evidence that nuclear egress of TDP-43 is size dependent; nuclear export of dTomato TDP-43 is significantly impaired compared to Flag TDP-43. Together, these results suggest nuclear export of TDP-43 is predominantly driven by passive diffusion.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 13 / 13/109 / 13/89 / 14 / 14/1 / 631/378/1689 / 631/80/389 / 82 / 82/47 / Active Transport, Cell Nucleus / Amino Acid Sequence / Amyotrophic lateral sclerosis / Animals / Binding Sites / Cell Line / Cytosol / DNA-Binding Proteins - chemistry / DNA-Binding Proteins - metabolism / Exportin 1 Protein / Fusion protein / Genes, Reporter / Humanities and Social Sciences / Humans / Hydrophobicity / Karyopherins - chemistry / Karyopherins - metabolism / Localization / Mice / Models, Molecular / multidisciplinary / Nuclear Export Signals / Nuclear transport / Protein Binding / Protein Conformation / Protein Interaction Domains and Motifs / Protein Transport / Proteins / Pyramidal Cells - metabolism / Rats / Receptors, Cytoplasmic and Nuclear - chemistry / Receptors, Cytoplasmic and Nuclear - metabolism / Ribonucleic acid / Ribonucleoside Diphosphate Reductase - chemistry / Ribonucleoside Diphosphate Reductase - metabolism / RNA / RNA-binding protein / Science / Science (multidisciplinary) / Splicing