Session Information
Date: Tuesday, June 21, 2016
Session Title: Pathophysiology (other movement disorders)
Session Time: 12:30pm-2:00pm
Location: Exhibit Hall located in Hall B, Level 2
Objective: To test the potential of induced pluripotent stem cell (iPSC)-derived cortical neurons from Myoclonus-dystonia (M-D) patients when studying specific epigenetic and brain-specific aspects of the disease.
Background: M-D patients typically present with dystonic features and myoclonic jerks. In some cases, this motor impairment is caused by mutations in ε-sarcoglycan (SGCE). SGCE-associated M-D is autosomal-dominantly inherited with reduced penetrance due to maternal imprinting. There are numerous SGCE mRNA isoforms including a predominant brain-specific and ubiquitous variant which encode a membrane-associated glycoprotein. To elucidate the so far unknown mechanisms underlying M-D, a model system which faithfully recapitulates endogenous features of the neurological disease is required.
Methods: iPSC lines were derived from fibroblasts of two M-D patients. Both patient lines as well as two control iPSC lines were differentiated into mature cortical neurons. Methylation of the SGCE promoter region was analyzed by bisulfite treatment and subsequent Sanger sequencing. The presence of SGCE isoforms was investigated by cDNA sequencing as well as quantitative PCR. To elucidate effects on protein level iPSC-derived cortical neurons were analyzed by Western blotting.
Results: Comparison of the SGCE promoter in control fibroblasts, iPSCs and iPSC-derived neurons showed tissue-independent differential methylation. Moreover, sequencing of neuronal DNA from patients with the W100G and the recurrent R102X mutations with methylation-specific primers indicated selective expression of the mutated paternal SGCE allele. While fibroblasts only expressed the ubiquitous mRNA isoform, ubiquitous and brain-specific SGCE transcripts were detected in iPSC-derived control neurons. In keeping with this finding, the protein encoded by the brain-specific mRNA isoform was highly abundant in control neurons. By contrast, we observed reduced ε-sarcoglycan levels in iPSC-derived neurons of both mutants. This can best be explained by nonsense-mediated decay for the R102X and enhanced protein degradation through the ubiquitin-proteasome system for the W100G-mutant case.
Conclusions: Our data highlight the suitability of iPSC-derived cortical neurons from patients with SGCE mutations for M-D research.
To cite this abstract in AMA style:
K. Grütz, P. Seibler, A. Weißbach, K. Lohmann, F.A. Carlisle, D.J. Blake, A. Westenberger, C. Klein, A. Grünewald. Faithful SGCE imprinting in iPSC-derived cortical neurons: An endogenous model system of myoclonus-dystonia [abstract]. Mov Disord. 2016; 31 (suppl 2). https://www.mdsabstracts.org/abstract/faithful-sgce-imprinting-in-ipsc-derived-cortical-neurons-an-endogenous-model-system-of-myoclonus-dystonia/. Accessed May 18, 2025.« Back to 2016 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/faithful-sgce-imprinting-in-ipsc-derived-cortical-neurons-an-endogenous-model-system-of-myoclonus-dystonia/