Long non-coding RNA SNHG18 epigenetic regulates ferroptosis in acute myocardial infarction

Abstract Background Loss of terminally differentiated cardiomyocytes is a key pathogenic factor for the occurrence of acute myocardial infarction (AMI) and the development of lethal heart failure. LncRNAs have been confirmed to be critical in regulating AMI, besides, recently published studies disclosed that ferroptosis is a new form of programmed cell death that contributes to AMI. However, whether LncRNAs are involved in the regulation of ferroptosis and correlated underlying mechanisms in AMI remains unknown. Purpose Our present study is to investigate LncRNA that regulates cardiomyocyte ferroptosis in AMI and uncover the potential mechanisms. Method RNA-sequencing and bioinformatical analyses were conducted to identify the candidate LncRNAs for AMI. Adenovirus for LncRNA knockout and overexpression were constructed to alter the SNHG18 expression of cardiomyocytes in vitro. Cardiomyocyte-specific knockout and overexpression mice were also constructed to alter SNHG18 expression in vivo. Ferroptosis characteristic measurement, including glutathione peroxidase 4 (GPX4), Ferritin heavy chain (FTH-1), ptgs2, MDA, ROS, Fe2+, glutathione, and mitochondrial morphology, was performed to verify the ability of SNHG18 to regulate the ferroptosis of cardiomyocytes. Cardiac morphological, structural, functional, and hemodynamic changes as well as the viability of cardiomyocytes were also measured to assess the effect of SNHG18 on AMI. RNA-pulldown+Mass spectrometry, RNA immunoprecipitation were performed to identify the specific binding factors of SNHG18. Results RNA-sequencing results revealed the expression of SNHG18 was significantly and persistently elevated from 3 to 7 days after AMI. SNHG18 was mainly enriched in the nucleus of cardiomyocytes. Besides, the down-regulation of SNHG18 could specifically alleviate the cell viability loss caused by ferroptosis inducers. Thereafter, gain- and loss-of-function experiments were performed both in vitro and in vivo. Functionally, SNHG18 knockout dramatically enhanced cardiomyocyte vitality, reduced infarct size, improved cardiac performance and alleviated cardiac fibrosis by mitigating cardiomyocyte ferroptosis. However, enforced SNHG18 expression resulted in the opposite effects. Mechanistically, the subunit RBBP4 that forms the PRC2 (Polycomb Repressive Complex 2) complex was a direct target of SNHG18, which was also confirmed by RIP assays. In addition, Chip-PCR analysis also demonstrated that PRC2 could directly bind to the promoter region of the GPX4 and FTH1 gene, thus altering the level of H3K27me3 and inhibiting their transcription. Moreover, subsequent rescue experiments further verified that SNHG18 regulated the expression of GPX4 and FTH1 to ameliorate AMI-induced cardiomyocyte ferroptosis in a PRC2-dependent manner. Conclusion This study demonstrates that SNHG18-PRC2-GPX4/FTH1 pathway is a promising therapeutic target for the treatment of AMI by ameliorating cardiomyocyte ferroptosis.