The role of the LncRNA-FA2H-2-MLKL pathway in atherosclerosis by regulation of autophagy flux and inflammation through mTOR-dependent signaling

Abstract

Atherosclerosis is a progressive, chronic inflammation in arterial walls. Long noncoding RNAs (lncRNAs) participate in inflammation, but the exact mechanism in atherosclerosis is unclear. Our microarray analyses revealed that the levels of lncRNA-FA2H-2 were significantly decreased by oxidized low-density lipoprotein (OX-LDL). Bioinformatics analyses indicated that mixed lineage kinase domain-like protein (MLKL) might be regulated by lncRNA-FA2H-2. In vitro experiments showed that lncRNA-FA2H-2 interacted with the promoter of the MLKL gene, downregulated MLKL expression, and the binding sites between −750 and 471 were necessary for lncRNA-FA2H-2 responsiveness to MLKL. Silencing lncRNA-FA2H-2 and overexpression of MLKL could activate inflammation and inhibited autophagy flux. Both lncRNA-FA2H-2 knockdown and overexpression of MLKL could significantly aggravate inflammatory responses induced by OX-LDL. We found that the 3-methyladenine (3-MA) and Atg7-shRNA enhanced inflammatory responses induced by knockdown of lncRNA-FA2H-2 and overexpression of MLKL. We demonstrated that the effects of MLKL on autophagy might be associated with a mechanistic target of rapamycin (mTOR)-dependent signaling pathways. In vivo experiments with apoE knockout mice fed a western diet demonstrated that LncRNA-FA2H-2 knockdown decreased microtubuleassociated expression of microtubule-associated protein 1 light chain 3 II and lysosome-associated membrane protein 1, but increased expression of sequestosome 1 (p62), MLKL, vascular cell adhesion molecule-1, monocyte chemoattractant protein-1, and interleukin-6 in atherosclerotic lesions. Our findings indicated that the lncRNA-FA2H-2-MLKL pathway is essential for regulation of autophagy and inflammation, and suggested that lncRNA-FA2H-2 and MLKL could act as potential therapeutic targets to ameliorate atherosclerosis-related diseases.

Long Non-Coding RNAs Link Oxidized Low-Density Lipoprotein With the Inflammatory Response of Macrophages in Atherogenesis

“…FA2H-2 was also reduced in ox-LDL treated ECs or SMCs and could inhibit the activity of NF-κB, which plays an important role -n inflammation. In addition, FA2H-2 also repressed autophagy by inhibiting mixed lineage kinase domain-like protein (MLKL), which can activate the inflammasome via the p38 MAPK/PI3K pathway (93). FA2H-2 could regulate ox-LDL induced inflammation, involved in the development of atherosclerosis.…”

Long non‑coding RNA MALAT1 regulates cholesterol accumulation in ox‑LDL‑induced macrophages via the microRNA‑17‑5p/ABCA1 axis

“…For example, chen et al (11) demonstrated that knockdown of lncRNA growth arrest specific 5 suppresses atherogenesis by regulating the apoptosis of macrophages and endothelial cells via exosomes. in addition, lncrna-Fa2H-2 has been shown to alleviate the inflammatory response, which acts as an independent risk factor of atherogenesis induced by oxidized low-density lipoprotein (ox-ldl), via the induction of the autophagic flux (12). These previous studies showed that lncrnas act as promoting or inhibiting factors in aS development.…”

Loss of MLKL Decreases Necrotic Core but Increases Macrophage Lipid Accumulation In Atherosclerosis

“…However, MLKL and Rab7 were not co-localized under acetylated LDL conditions, which is known to be less inflammatory than oxidized and aggregated LDL, and where fewer MLKL positive punctate structures were seen. Others have shown in vitro that MLKL inhibits autophagic flux in non-macrophage cell types, therefore it is unlikely that the absence of MLKL would lead to reduced autophagy of lipid droplets 24,25 . Rather, we hypothesize that MLKL regulates the tethering of Rab7-positive late endosomes and/or multivesicular bodies (MVBs) at ER-endosome contact sites, possibly via ESCRT machinery to regulate lipid droplet mobilization 14,19 .…”