Inhibition of MicroRNA-183 Attenuates Pathological TDP-43 Aggregation via SQSTM1/p62 in ALS
Liang Lu1, Han-Cheon Kim2, Yan Zhang1, Peter King3
1BCM, 2UTH, 3UAB
Objective:
To define miR-183-5p as a viable target for TDP-43 aggregation and neurotoxicity, and to validate its therapeutic role in reversing TDP-43 pathology in ALS.
Background:
Emerging evidence indicates that miRNA dysregulation is associated with neuronal toxicity and mitochondrial dysfunction, and also plays a pivotal role in ALS pathogenesis. MiR-183-5p was found to be elevated in serum exosomes from ALS patients. We recently reported that miR-183-5p is aberrantly upregulated in spinal cord tissues of ALS patients and promotes TDP-43 aggregation, mislocalization and neurotoxicity. Protein aggregation is a common pathological hallmark in neurodegenerative disease, and TDP-43 aggregation plays a key role in the pathogenesis of ALS. Preventing TDP-43 aggregation is therefore a rational approach for mitigating disease pathology.
Design/Methods:
Real-time qPCR will be used to analyze miR-183-5p expression. ALS disease protein TDP-43 will be analyzed by western blot with miR-183-5p inhibitor transduced-neuronal cells. Soluble and insoluble fractions will be used to analyze the mitigation of TDP-43 aggregation. Immunostaining was used to visualize TIA1-positive SGs and subcellular location of mutant TDP-43.
Results:
MiR-183-5p increased TDP-43 expression, aggregation and stress-induced cytotoxicity. SQSTM1/p62 was suppressed by miR-183-5p via the 3’ untranslated region. Silencing SQSTM1/p62 recapitulates the increase in TDP-43 expression and aggregation as observed with miR-183-5p. Under heat shock and oxidative stress, we observed cytoplasmic association and stress granules of TDP43 and p62. The miR-183-5p antagomir repressed formation of stress granules and aggregated TDP43 protein in neuronal cells under stress-induced conditions and protected against cytotoxicity. These findings suggest that the miR-183-5p-SQSTM1/p62 axis plays a key role in the pathophysiology of ALS by promoting TDP-43 aggregation and cellular toxicity.
Conclusions:
Our discovery of miR-183-5p as a novel regulator of TDP-43 aggregation via p62 highlights the convergence of abnormal RNA processing and protein recycling in ALS pathogenesis, providing a therapeutic target to rescue TDP-43 pathology in ALS.