H3K9 trimethylation dictates neuronal ferroptosis through repressing Tfr1

Area of Science:

• Neuroscience
• Epigenetics
• Cellular Biology

Background:

• Spontaneous intracerebral hemorrhage (ICH) causes significant global mortality and morbidity.
• Ferroptosis, a form of programmed cell death driven by iron overload and glutathione peroxidase 4 (GPx4) dysfunction, contributes to neuronal loss in ICH.
• The role of epigenetic regulation in ferroptosis following ICH is not well understood.

Purpose of the Study:

• To investigate the epigenetic mechanisms, specifically histone modifications, that regulate ferroptosis in neurons after ICH.
• To elucidate the role of histone 3 lysine 9 trimethylation (H3K9me3) and its associated methyltransferase Suv39h1 in ferroptosis post-ICH.

Main Methods:

• Hemin was used to induce ferroptosis in N2A and SK-N-SH neuronal cell lines.
• Global H3K9me3 levels and Suv39h1 expression were assessed post-hemin stimulation.
• Chromatin immunoprecipitation sequencing (ChIP-seq) was performed to identify H3K9me3 targets.
• Inhibition of H3K9me3 or Suv39h1 was achieved using chemical inhibitors or siRNA.
• Ferroptosis was evaluated using cell viability assays and iron assays.
• ICH progression was studied in a mouse model.

Main Results:

• Hemin-induced ferroptosis in neuronal cells correlated with increased global H3K9me3 and Suv39h1 levels.
• H3K9me3 was found to be enriched at the promoter and gene body of transferrin receptor 1 (Tfr1), repressing its expression.
• Inhibition of H3K9me3 or Suv39h1 exacerbated ferroptosis, which was associated with increased Tfr1 expression.
• Suv39h1-mediated repression of Tfr1 was shown to be protective against ferroptosis progression in an ICH mouse model.

Conclusions:

• Epigenetic regulation by H3K9me3, mediated by Suv39h1, plays a protective role in mitigating ferroptosis post-ICH.
• The H3K9me3-Suv39h1-Tfr1 pathway represents a novel epigenetic mechanism influencing neuronal survival in intracerebral hemorrhage.
• Understanding this epigenetic pathway may lead to new therapeutic strategies for managing ICH.