Abstract 864 Long non-coding RNA Snhg15 is required for cell survival and nucleolar stability in cardiomyocytes

Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5
Long non-coding RNA Snhg15 is required for cell survival and nucleolar stability in cardiomyocytes
M. Shumliakivska¹, G. Aslan¹, A. Tamiato¹, L. Tombor¹, J. U. G. Wagner¹, Y. Manavski¹, G. Luxan¹, S. Dimmeler¹
¹Zentrum für Molekulare Medizin, Institut für Kardiovaskuläre Regeneration, Universitätsklinikum Frankfurt, Frankfurt am Main;
Background: Cardiovascular disease (CVD) is the most common cause of mortality in the world. Heart failure is a CVD condition that can include cardiac remodelling characterized by extensive fibrosis, endothelial dysfunction and cardiomyocyte hypertrophy. In the case of ischemic heart failure, massive loss of cardiomyocytes occurs. Therefore, strategies that promote cardiomyocytes survival could have a potential therapeutic application. Recently, non-coding RNAs emerged as a new class of cellular function regulators in CVD. Long non-coding RNAs (lncRNAs) from small nucleolar RNA hosting gene (SNHG) family have been studied in field of cancer metastasis, but their role in cardiovascular pathologies remains vastly unknown. In the present study, we investigated the role of lncRNA SNHG15/Snhg15 in heart failure progression and in cardiomyocyte survival specifically. Methods and Results: Using bulk RNA sequencing data of cardiac tissue from healthy and heart failure patients, we identified lncRNA SNHG15 to be 77.76% downregulated in patients with heart failure (p<0.01). To assess the function of this lncRNA, we tested the effects of SNHG15/Snhg15 using GapmeR-mediated silencing in cardiac fibroblasts and HL-1 cardiomyocytes in vitro (56.35% and 70.94% reduction, respectively, p<0.05). Whereas no effects were observed in fibroblasts, silencing of Snhg15 reduced cell survival by 72.63% in cardiomyocytes in vitro (p<0.0001). Reduced cell survival was associated with an activation of caspases-3 and 7 in vitro (p<0.0001), while proliferation of HL-1 cardiomyocytes was not affected. Furthermore, cells both in early and late apoptosis were detected upon Snhg15 silencing (p<0.0001). Immunocytological studies additionally demonstrated that GapmeR-mediated depletion of lncRNA Snhg15 induced nucleolar damage by 20.53 fold, which is directly connected to cell apoptosis progression (p<0.01). Consistently, nucleolar damage was observed in cardiomyocytes in mice hearts after myocardial infarction (p<0.01). To decipher potential mechanisms underlying the effects, we took advantage of proteome arrays that identified p53 protein being positively regulated in cardiomyocytes after GapmeR Snhg15 treatment. Specifically, on the gene expression level Trp53 was overexpressed by 1.43 fold and on protein level by 1.49 fold (p<0.05). Furthermore, qRT-PCR analysis revealed the overexpression of p53-regulated genes, Pidd1 and Puma, and the activation of the programmed cell death pathway (p<0.05). Conclusion: LncRNA Snhg15 is downregulated in human heart failure and its silencing induces nucleolar damage and apoptosis in cardiomyocytes in vitro. Our findings suggest that p53 might be mediating nucleaolar damage and apoptosis upon Snhg15 silencing. Maintaining or inducing the expression of lncRNA Snhg15 expression after myocardial infarction might be an interesting therapeutic approach to reduce cardiomyocyte death and to possibly improve patient outcome after myocardial infarction. Keywords: CVD, lncRNAs, nucleolar damage, cardiomyocyte apoptosis.
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