Journal Article

SUMOylation Regulates TDP-43 Splicing Activity and Nucleocytoplasmic Distribution

Dragotto, Jessica, Mompeán, Miguel, Colombrita, Claudia, Gumina, Valentina, Feligioni, Marco, Maraschi, AnnaMaria, Ratti, Antonia, Buratti, Emanuele, Silani, Vincenzo

2021

Overview

The nuclear RNA-binding protein TDP-43 forms abnormal cytoplasmic aggregates in the brains of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) patients and several molecular mechanisms promoting TDP-43 cytoplasmic mislocalization and aggregation have been proposed, including defects in nucleocytoplasmic transport, stress granules (SG) disassembly and post-translational modifications (PTM). SUMOylation is a PTM which regulates a variety of cellular processes and, similarly to ubiquitination, targets lysine residues. To investigate the possible regulatory effects of SUMOylation on TDP-43 activity and trafficking, we first assessed that TDP-43 is SUMO-conjugated in the nuclear compartment both covalently and non-covalently in the RRM1 domain at the predicted lysine 136 and SUMO-interacting motif (SIM, 106–110 residues), respectively. By using the SUMO-mutant TDP-43 K136R protein, we demonstrated that SUMOylation modifies TDP-43 splicing activity, specifically exon skipping, and influences its sub-cellular localization and recruitment to SG after oxidative stress. When promoting deSUMOylation by SENP1 enzyme over-expression or by treatment with the cell-permeable SENP1 peptide TS-1, the cytoplasmic localization of TDP-43 increased, depending on its SUMOylation. Moreover, deSUMOylation by TS-1 peptide favoured the formation of small cytoplasmic aggregates of the C-terminal TDP-43 fragment p35, still containing the SUMO lysine target 136, but had no effect on the already formed p25 aggregates. Our data suggest that TDP-43 can be post-translationally modified by SUMOylation which may regulate its splicing function and trafficking, indicating a novel and druggable mechanism to explore as its dysregulation may lead to TDP-43 pathological aggregation in ALS and FTD.

• Publisher: Springer US,Springer Nature B.V
• Subject: Amyotrophic lateral sclerosis / Biomedical and Life Sciences / Biomedicine / Cell Biology / Cell Line, Tumor / Cell Nucleus - chemistry / Cytoplasm - chemistry / Dementia disorders / DNA-Binding Proteins - analysis / DNA-Binding Proteins - metabolism / Exon skipping / Frontotemporal dementia / HEK293 Cells / Humans / Localization / Lysine / Models, Molecular / Molecular Dynamics Simulation / Molecular modelling / Nerve Tissue Proteins - analysis / Nerve Tissue Proteins - metabolism / Neurobiology / Neuroblastoma / Neurology / Neurosciences / Original / Original Article / Overexpression / Oxidative stress / Peptide Fragments - pharmacology / Peptides / Post-translation / Potassium Chloride - pharmacology / Protein Conformation / Protein Processing, Post-Translational / Protein Transport / RNA Interference / RNA Splicing / RNA, Small Interfering - pharmacology / RNA-binding protein / Sequence Alignment / Sequence Homology, Amino Acid / Splicing / Stress Granules / SUMO protein / Sumoylation / Ubiquitination