Aberrant DNA and RNA Methylation Occur in Spinal Cord and Skeletal Muscle of Human SOD1 Mouse Models of ALS and in Human ALS: Targeting DNA Methylation Is Therapeutic

Abstract

Amyotrophic lateral sclerosis (ALS) is a fatal disease. Skeletal muscles and motor neurons (MNs) degenerate. ALS is a complex disease involving many genes in multiple tissues, the environment, cellular metabolism, and lifestyles. We hypothesized that epigenetic anomalies in DNA and RNA occur in ALS and examined this idea in: (1) mouse models of ALS, (2) human ALS, and (3) mouse ALS with therapeutic targeting of DNA methylation. Human superoxide dismutase-1 (hSOD1) transgenic (tg) mice were used. They expressed nonconditionally wildtype (WT) and the G93A and G37R mutant variants or skeletal muscle-restricted WT and G93A and G37R mutated forms. Age-matched non-tg mice were controls. hSOD1 mutant mice had increased DNA methyltransferase enzyme activity in spinal cord and skeletal muscle and increased 5-methylcytosine (5mC) levels. Genome-wide promoter CpG DNA methylation profiling in skeletal muscle of ALS mice identified hypermethylation notably in cytoskeletal genes. 5mC accumulated in spinal cord MNs and skeletal muscle satellite cells in mice. Significant increases in DNA methyltransferase-1 (DNMT1) and DNA methyltransferase-3A (DNMT3A) levels occurred in spinal cord nuclear and chromatin bound extracts of the different hSOD1 mouse lines. Mutant hSOD1 interacted with DNMT3A in skeletal muscle. 6-methyladenosine (6mA) RNA methylation was markedly increased or decreased in mouse spinal cord depending on hSOD1-G93A model, while fat mass and obesity associated protein was depleted and methyltransferase-like protein 3 was increased in spinal cord and skeletal muscle. Human ALS spinal cord had increased numbers of MNs and interneurons with nuclear 5mC, motor cortex had increased 5mC-positive neurons, while 6mA was severely depleted. Treatment of hSOD1-G93A mice with DNMT inhibitor improved motor function and extended lifespan by 25%. We conclude that DNA and RNA epigenetic anomalies are prominent in mouse and human ALS and are potentially targetable for disease-modifying therapeutics.

Hypothermic Protection in Neocortex Is Topographic and Laminar, Seizure Unmitigating, and Partially Rescues Neurons Depleted of RNA Splicing Protein Rbfox3/NeuN in Neonatal Hypoxic-Ischemic Male Piglets

“…Similarly, we identified the somatosensory cortex by cytology and its connectivity with the putamen, thalamus, and cortico-cortical connections. The cytology was similar to what has been described for humans [77,84,89,90]. We evoked limited motor responses and somatosensory-evoked potential recordings to assist in identifying these regions, which corresponded to the electrophysiological mapping of pigs conducted by other researchers [82,91].…”

From Environment to Gene Expression: Epigenetic Methylations and One-Carbon Metabolism in Amyotrophic Lateral Sclerosis

“…Yet, no global DNA methylation changes were detected, suggesting that the beneficial effect of decitabine was independent of DNMT inhibition [123]. In accordance with this, the two DNMT inhibitors 5-Fluoro-2 ′ -deoxycitidine and RG108 did not show any effect on DPR production in this humanized culture model [123], in spite of the previously reported protective effect of RG108 in the SOD1 G93A mouse model of ALS [57]. Decitabine efficiency was instead proposed to be mediated by impaired repeat transcription [123].…”

Chromatin modifiers in human disease: from functional roles to regulatory mechanisms

“…Ginsenoside nanoparticles induce the expression of histone demethylases JMJD3 and UTX to increase the levels of demethylation in the promoter regions of VEGF-A and Jagged1, thereby promoting angiogenesis in rats with ischemic stroke [ 108 ]. Highly expressed DNMT1 and DNMT3A were detected in the spinal cord and skeletal muscle of mice with amyotrophic lateral sclerosis; however, treatment with the DNMT inhibitor RG108 improved motor function and prolonged survival in the affected mice [ 109 ].…”