Linking epigenetic dysregulation, mitochondrial impairment, and metabolic dysfunction in SBMA motor neurons
Naemeh Pourshafie, … , Christopher Grunseich, Kenneth H. Fischbeck
Naemeh Pourshafie, … , Christopher Grunseich, Kenneth H. Fischbeck
Published July 9, 2020
Citation Information: JCI Insight. 2020;5(13):e136539. https://doi.org/10.1172/jci.insight.136539.
View: Text | PDF
Research Article Genetics Neuroscience

Linking epigenetic dysregulation, mitochondrial impairment, and metabolic dysfunction in SBMA motor neurons

Abstract

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disorder caused by a polyglutamine expansion in the androgen receptor (AR). Using gene expression analysis and ChIP sequencing, we mapped transcriptional changes in genetically engineered patient stem cell–derived motor neurons. We found that transcriptional dysregulation in SBMA can occur through AR-mediated histone modification. We detected reduced histone acetylation, along with decreased expression of genes encoding compensatory metabolic proteins and reduced substrate availability for mitochondrial function. Furthermore, we found that pyruvate supplementation corrected this deficiency and improved mitochondrial function and SBMA motor neuron viability. We propose that epigenetic dysregulation of metabolic genes contributes to reduced mitochondrial ATP production. Our results show a molecular link between altered epigenetic regulation and mitochondrial metabolism that contributes to neurodegeneration.

Authors

Naemeh Pourshafie, Ester Masati, Eric Bunker, Alec R. Nickolls, Parisorn Thepmankorn, Kory Johnson, Xia Feng, Tyler Ekins, Christopher Grunseich, Kenneth H. Fischbeck

×

Figure 5

Sodium pyruvate treatment improves SBMA mitochondrial function and increases SBMA iMN survival.

Options: View larger image (or click on image) Download as PowerPoint
Sodium pyruvate treatment improves SBMA mitochondrial function and incre...
(A) A simplified metabolic flow diagram linking oxidative phosphorylation and histone acetylation. ACSL1, ACSL3, and BCAT2 are genes with greater than 2-fold reduced H3K27ac identified from the ChIP-seq data (SBMA versus control). (B) Relative acetyl-CoA levels. iMNs were grown in triplicate wells from the same batch of differentiation. (C and D) Bioenergetic extracellular flux analysis on iMNs treated with 20 mM sodium pyruvate from 2–6 dpi, every 2 days. (C) OCR in control (top) and SBMA (bottom) after 48-hour treatment with sodium pyruvate. Oligomycin, or antimycin/rotenone (A/R) treatments were given at the indicated time points. (D) Rate of mitochondrial ATP production in iMNs treated with sodium pyruvate. Cells were grown in triplicate wells per cell line/per condition. Error bars show mean ± SE; *P < 0.05, **P < 0.01, 2-tailed Student’s t tests. (E) Relative acetyl-CoA levels in control iMNs treated with DMSO and a mix of ETC inhibitor cocktail (1.5 μM oligomycin, 0.5 μM of each antimycin and rotenone). iMNs were treated for 8 hours or 24 hours. Cells were grown in triplicate wells from the same batch of differentiation. (F and G) Real-time cell viability assessment of iMNs treated with 20 mM sodium pyruvate using NucGreen dead 488. (F) Representative images of SBMA iMNs treated with sodium pyruvate. NucGreen dead 488 (Green) and DAPI (blue). Scale bar: 50 μm. (G) For quantification, 4 images per cell line were taken at each time point. Error bars show mean ± SE; ***P < 0.001, 2-tailed Student’s t tests. All experiments were performed on N = 3 SBMA, N = 3 control, and N = 3 AR-KO. Error bars show mean ± SE; *P < 0.05 and **P < 0.01; 1-way ANOVA followed by Bonferroni’s multiple comparisons test, unless otherwise indicated. iMNs were treated with 10 nM DHT.