Small-molecule modulators of TRMT2A decrease PolyQ aggregation and PolyQ-induced cell death

Polyglutamine (polyQ) diseases, including Huntington's disease, are characterized by an expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats encoding for an uninterrupted prolonged polyQ tract. We previously identified TRMT2A as a strong modifier of polyQ-induced toxicity in an unbiased large-scale screen in Drosophila melanogaster. RNAi-mediated silencing of TRMT2A ameliorated polyQ-induced toxicity and polyQ aggregation in flies. This work aimed at identifying and validating pharmacological TRMT2A inhibitors as treatment opportunities for polyQ diseases. An in silico structure- and ligand-based lead discovery approach and computer-aided drug discovery (CADD) was used to identify TRMT2A inhibitors. Additionally, the crystal structure of one protein domain, the RNA recognition motif (RRM), was determined and Biacore experiments with the RRM were performed. The identified inhibitors were functionally validated for their potency to reduce polyQ aggregation and polyQ-induced cell death in human HEK293T cells and patient derived fibroblasts. Several candidate molecules were able to decrease cell death and ameliorate the aggregation of polyQ peptides in cultured cells comparable to the TRMT2A knockdown experiments. Among these, spermidine was identified as able to cause a decrease in the abundance of polyQ aggregates in SCA3-patient derived fibroblasts. Our work provides a first step towards a pharmacological inhibition of this enzyme and indicates TRMT2A as a viable drug target for polyQ diseases.

Dystonia in Patients with Spinocerebellar Ataxia 3 - Machado-Joseph disease: An Underestimated Diagnosis?

Background:Spinocerebellar Ataxia type 3 (SCA3) or Machado-Joseph Disease (MJD) is characterized by cerebellar, central and peripheral symptoms, including movement disorders. Dystonia can be classified as hereditary and neurodegenerative when present in SCA3.Objective:The objective of this study was to evaluate the dystonia characteristics in patients with MJD.Method:We identified all SCA3 patients with dystonia from the SCA3 HC-UFPR database, between December 2015 and December 2016.Their medical records were reviewed to verify the diagnosis of dystonia and obtain demographic and clinical data. Standardized evaluation was carried out through the classification of Movement Disorders Society of 2013 and Burke Fahn-Marsden scale (BFM).Results:Amongst the presenting some common characteristics, 381 patients with SCA3, 14 (3.7%) subjects presented dystonia: 5 blepharospasm, 1 cervical dystonia, 3 oromandibular, 3 multifocal and 2 generalized dystonia. Regarding dystonia's subtypes, 71.4% had SCA3 subtype I and 28.6% SCA3 subtype II. The average age of the disease onset was 40±10.7 years; the SCA3 disease duration was 11.86± 6.13 years; the CAG repeat lengths ranged from 75 to 78, and the BFM scores ranged from 1.0 to 40. There was no correlation between the dystonia severity and CAG repeat lengths or the SCA3 clinical evolution.Conclusion:Dystonia in SCA3 is frequent and displays highly variable clinical profiles and severity grades. Dystonia is therefore a present symptom in SCA3, which may precede the SCA3 classic symptoms. Dystonia diagnosis is yet to be properly recognized within SCA3 patient.