The increase of Nrf2 m6A modification induced by FTO downregulation promotes hippocampal neuron injury and aggravates the progression of epilepsy in a rat model

Abstract

Epilepsy is a common chronic neurological disorder characterized by widespread neuronal death. The purpose of this study was to investigate the role of nuclear factor erythroid 2‐related factor 2 (Nrf2) m6A methylation in epilepsy. To create epileptic models, the rats were given Lithium chloride and pilocarpine, and isolated primary rat hippocampal neurons were cultured in an Mg2+‐free medium. The frequency of seizures was recorded in the epilepsy group of rats. The functional tests included TUNEL, MTT, and flow cytometry. Mechanistically, RNA degradation assay, RNA immunoprecipitation, and methylated RNA immunoprecipitation were performed. In epileptic models, Nrf2 and fat mass and obesity‐associated (FTO) levels were downregulated, whereas YT521‐B homology (YTH) domain family protein 2 (YTHDF2) was upregulated. Additionally, in epileptic models, there was a rise in the m6A methylation level of Nrf2 mRNA. Overexpressing FTO increased cell viability and reduced apoptosis, but Nrf2 interference reversed these effects. Meanwhile, FTO overexpression decreased the m6A methylation of Nrf2 mRNA. Moreover, YTHDF2 bound to Nrf2 mRNA and decreased its stability. Furthermore, FTO overexpression reduced seizure frequency in rats and inhibited hippocampal neuron apoptosis via lowering the m6A methylation level of Nrf2 mRNA. Overexpressing FTO reduced m6A methylation of Nrf2 mRNA, increased cell viability, suppressed apoptosis, and slowed the progression of epileptic diseases, which is linked to YTHDF2 binding to m6A‐modified Nrf2 and promoting its degradation, as well as downregulating Nrf2 expression in hippocampal neurons.

METTL14/YTHDC1-Mediated m6A Modification in Hippocampus Improves Pentylenetetrazol-Induced Acute Seizures

“…As PTZ challenges only lead to reduced expression of hippocampal YTHDC1, and METTL14 over-expression increased the expression of YTHDC1, so we can conclude YTHDC1 may be the key m6A-binding protein under acute seizures condition. Although previous study showed YTHDF2 was up-regulated in rat epileptic models induced by lithium chloride and pilocarpine [29]. Exactly, YTHDC1 is preferentially expressed in the hippocampus of mouse brains.…”

“…The N6-methyladenine (m6A) modi cation is one of the most common posttranscriptional RNA modi cations in eukaryotes. Although m6A modi cation is involved in epileptogenesis, such as a recent research veri ed that m6A modi cation play a vital role in hippocampal neuron injury and the progression of epilepsy in a rat model [29]; another study also demonstrated that m6A modi cation was related to immune cell components, cell death patterns and glucose metabolism in the pathogenesis of epilepsy [14]. The results of our tests similarly showed that in acute seizures induced by PTZ injection, the m6A level was signi cantly reduced in the hippocampal of mice, as revealed by m6A-ELISA, m6A-IHC and m6A-dot blot tests, indicating lower m6A level could aggravate the progression of epilepsy.…”

Mechanism of Fat Mass and Obesity‐Related Gene‐Mediated Heme Oxygenase‐1 m6A Modification in the Recovery of Neurological Function in Mice with Spinal Cord Injury

“… 32 Upregulation of FTO also suppressed Nrf2 mRNA m6A methylation, leading to enhanced cell viability and reduced apoptosis in rats. 33 …”