Increased m6A-RNA methylation and FTO suppression is associated with myocardial inflammation and dysfunction during endotoxemia in mice

Abstract

Endotoxemia triggers life-threatening immune and cardiovascular response that leads to tissue damage, multi-organ failure, and death. The understanding of underlying molecular mechanisms is still evolving. N6-methyladenosine (m6A) RNA modification plays key regulatory role in numerous biological processes. However, it remains unclear whether endotoxemia alters RNA methylation in the myocardium. In the current study, we investigated the effect of LPS-induced endotoxemia on m6A-RNA methylation and its implications on myocardial inflammation and left ventricular (LV) function. Following LPS administration, mice showed increases in m6A-RNA methylation in the myocardium with a corresponding decrease in the expression of Fat mass and obesity-associated protein (FTO, an m6A eraser/demethylase). The changes were associated with a significant increase in expression of myocardial inflammatory cytokine genes, such as IL-6, TNF-α, IL-1β, and reduced LV function. Moreover, rat cardiomyoblasts (H9c2) exposed to LPS showed similar changes (with increase in m6A-RNA methylation and inflammatory cytokine genes, whereas downregulation of FTO). Furthermore, methylated RNA immunoprecipitation (MeRIP) assay showed hypermethylation and increase in the expression of IL-6 and TNF-α genes in LPS-treated H9c2 cells as compared to untreated cells. Interestingly, FTO knockdown in cardiomyocytes mimicked the above effects. Taken together, these data suggest that endotoxemia-induced m6A methylation might play a critical role in expression of cardiac proinflammatory cytokines, and modulation of m6A methylation might limit myocardial inflammation and dysfunction during endotoxemia.

m6A demethylase Fto regulates TNF-α-induced inflammatory response in cementoblasts

“…Here, we found m 6 A demethylase Fto knockdown upregulated in ammatoryrelated genes (Il-6, Mcp1, and Mmp9) after TNF-α stimulation in OCCM-30 cells. Consistently, Dubey [23] and McFadden[38] revealed that knockdown or depletion of FTO generally led to a strong upregulation of proin ammatory cytokines TNF-α and IL-6, respectively. In the contrast, some articles claimed that FTO overexpression signi cantly enhanced in ammatory responses in human cardiomyocyte AC16 cell line [24] or RAW264.7 cells and bone marrow-derived macrophages [37].…”

“…The expression of in ammatory cytokines is tightly linked with the activation of NF-κB and MAPK signaling pathways [35,36]. Furthermore, accumulating evidence has indicated that m 6 A mRNA modi cation contributes to different functions via MAPK and NF-κB signaling pathways [23,[39][40][41][42]. We found that Fto knockdown upregulated Il-6, Mcp1, and Mmp9 in TNF-α-induced OCCM-30 cells.…”

“…Increasing studies have shown that Fto involves in multiple in ammatory disorders [23][24][25][26][27][28]. Here, we established apical periodontitis model to know whether Fto is also involved in it.…”

“…Thus, we speculated that expression of Fto is downregulated in cementoblasts in an in ammatory environment. Dubey reported that LPS-induced endotoxemia signi cantly downregulated FTO [23], thus they observed an increase in global m 6 A-RNA methylation in the cardiac tissues of LPS-induced endotoxemic mice and in LPS-induced H9c2 cardiomyoblasts. Consistently, previous research [37] also claimed that LPS suppressed FTO in RAW264.7 macrophages, which explained the upregulating Socs1 m 6 A methylation in LPS-treated macrophages activation.…”

“…More importantly, previous studies have shown that FTO involves in multiple in ammatory disorders. Dubey et al [23] and Yu et al [24] reported that loss-of-function of FTO upregulated LPS-induced rat cardiomyoblasts expression of in ammatory cytokine genes or inhibited palmitic acid-induced cardiac in ammation, respectively. Luo et al [25] found that ablation of FTO suppressed the NLRP3 in ammasome, on the contrary, Yu et al [26] exhibited that overexpression of FTO inhibited activation of the NLRP3 in ammasome.…”