Abstract Details

Title Suppression of MicroRNA-9-5p Mitigates TDP-43 Neurotoxicity in ALS

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P1 - Poster Session 1 (8:00 AM-9:00 AM)

Poster/Presentation
Number 11-005

Objective

To define miR-9-5p as a novel TDP-43 regulator via HuR 3-UTR and inhibition of miR-9-5p acts as a potent rescuer of TDP-43 toxicity; and to analyze its functional impact on protein clearance of pathological forms of TDP-43 in ALS pathogenesis.

Background Various microRNAs are aberrantly expressed and processed in ALS cellular and animal models, which leads to neuronal toxicity and cell death. The cytoplasmic aggregation of TDP-43 is a key pathology observed in motor neurons in patients with ALS. We have previously demonstrated HuR as a master regulator of TDP-43 through posttranscriptional mechanism. Through this pathway, we have identified several microRNA candidates including miR-9-5p that modulate HuR through its 3’-UTR. The removal of pathological aggregates and the rescue of TDP-43 mislocalization may be critical for reversing TDP-43 proteinopathies.

Design/Methods Quantitative PCR was used to analyze the miR-9-5p mRNA in spinal cords from ALS patients. TDP-43 expression levels were analyzed by western blot after miR-9-5p or its inhibitor was transfected into U251 cells. A proteasomal marker d2EGFP was used to access the integrity of ubiquitin proteasome pathway affected by inhibitor of miR-9-5p. Soluble and insoluble fractions were isolated for insolubility assay for mutant TDP-43 or under proteasomal stress. Immunostaining was used to visualize TIA1-positive SGs and subcellular location of mutant TDP-43.

Results miR-9-5p is significantly upregulated in ALS spinal cord as a key negative regulator of HuR. It regulates TDP-43 and HuR expression via its 3’UTR. The inhibition of miR-9-5p promotes stress granules, proteasomal degradation of d2EGFP. Further, inhibition of miR-9-5p alleviated the insoluble aggregates of TDP-43 mutants, and restored nuclear localization of truncated C-terminal TDP-43.

Conclusions

miR-9-5p is upregulated in ALS spinal cords, and regulates several cytopathological features of TDP-43 proteinopathy related to ALS. Inhibitor of miR-9-5p presents a potential therapeutic strategy to reverse TDP-43 pathology in ALS.

Authors/Disclosures
Liang Lu, MD, FAAN (MEDVAMC/BCM) PRESENTER	Dr. Lu has nothing to disclose.
Yan Zhang	No disclosure on file
Han-Cheon Kim	No disclosure on file

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