Functional and Molecular Properties of DYT-SGCE Myoclonus-Dystonia Patient-Derived Striatal Medium Spiny Neurons

Abstract

Myoclonus-dystonia (DYT-SGCE, formerly DYT11) is characterized by alcohol-sensitive, myoclonic-like appearance of fast dystonic movements. It is caused by mutations in the SGCE gene encoding ε-sarcoglycan leading to a dysfunction of this transmembrane protein, alterations in the cerebello-thalamic pathway and impaired striatal plasticity. To elucidate underlying pathogenic mechanisms, we investigated induced pluripotent stem cell (iPSC)-derived striatal medium spiny neurons (MSNs) from two myoclonus-dystonia patients carrying a heterozygous mutation in the SGCE gene (c.298T>G and c.304C>T with protein changes W100G and R102X) in comparison to two matched healthy control lines. Calcium imaging showed significantly elevated basal intracellular Ca2+ content and lower frequency of spontaneous Ca2+ signals in SGCE MSNs. Blocking of voltage-gated Ca2+ channels by verapamil was less efficient in suppressing KCl-induced Ca2+ peaks of SGCE MSNs. Ca2+ amplitudes upon glycine and acetylcholine applications were increased in SGCE MSNs, but not after GABA or glutamate applications. Expression of voltage-gated Ca2+ channels and most ionotropic receptor subunits was not altered. SGCE MSNs showed significantly reduced GABAergic synaptic density. Whole-cell patch-clamp recordings displayed elevated amplitudes of miniature postsynaptic currents and action potentials in SGCE MSNs. Our data contribute to a better understanding of the pathophysiology and the development of novel therapeutic strategies for myoclonus-dystonia.

Cortical neuronal hyperexcitability and synaptic changes in SGCE mutation-positive myoclonus dystonia

“…60,61 In addition, a recent SGCE-mutation positive patient derived iPSC model, differentiated towards a medium spiny neuron (MSN) lineage also demonstrated significantly higher basal intracellular Ca2+ levels and smaller transient amplitudes, although found no significant difference in the handling, particularly of intracellular stores, represents a common theme in dystonia pathogenesis, although these changes may differ between neuronal types. 61,62 Evaluation of the differences in single-cell AP shape provide further insights into the potential mechanisms underlying the observed hyperexcitability. Here, SGCE-mutations were associated with more negative AP thresholds, larger amplitudes, shorter half-widths, and faster rise and fall times.…”

Reduced Expression of GABAA Receptor Alpha2 Subunit Is Associated With Disinhibition of DYT-THAP1 Dystonia Patient-Derived Striatal Medium Spiny Neurons

“…The matched healthy control-derived iPSC lines were characterized previously (Japtok et al, 2015;Glaß et al, 2018). Data of these healthy control lines have also been included in another manuscript (Kutschenko et al, 2021). For the sake of visual clarity, we decided to illustrate bar graphs with pooled data of control cell lines and THAP1 mutation carriers, respectively.…”

Innate immune response to SARS-CoV-2 infection contributes to neuronal damage in human iPSC-derived peripheral neurons

“…To perform a comparative analysis of SARS-CoV-2 infection in PNS and CNS neurons, we employed protocols developed in our laboratories to differentiate human iPSC into neurons with characteristics of sensory and striatal medium spiny neurons (MSN) (schematic depiction in Figure 1A and 1B) (Kutschenko et al, 2021; Zhu et al, 2021). We will refer to the sensory neurons and MSN as PNS and CNS neurons, respectively.…”

“…Differentiation of human iPSC-derived CNS and PNS neurons, and their expression profiles of SARS-CoV-2 receptors and entry factors. (A,B) PNS (A) and CNS (B) neurons were differentiated from iPSC adding the indicated supplements at the corresponding time points (Kutschenko et al, 2021; Zhu et al, 2021). (C) Graphs showing relative expression of ACE2, TMPRSS2 and NRP1 in iPSC-derived CNS neurons (left) and PNS neurons (middle) and that of ACE2 in Vero76 cells (right).…”

“…Sensory neurons and MSNs were derived from iPSC and maintained as previously described (Kutschenko et al, 2021; Zhu et al, 2021). To differentiate sensory neurons, we employed small molecule derived neuronal precursor cells (smNPCs) generated from cord blood-derived iPSC (Naujock et al, 2014).…”