RÉSUMÉ
Macrophage lipid accumulation is a critical contributor to foam cell formation and atherosclerosis. Tumor necrosis factor-α-induced protein 1 (TNFAIP1) is closely associated with cardiovascular disease. However, its role and molecular mechanisms in atherogenesis remain unclear. TNFAIP1 was knocked down in THP-1 macrophage-derived foam cells and apolipoprotein-deficient (apoE-/-) mice using lentiviral vector. The expression of lncRNA enhancing endothelial nitric oxide synthase expression (LEENE), Forkhead box O1 (FoxO1) and ATP binding cassette transporter A1 (ABCA1) was evaluated by qRT-PCR and/or western blot. Lipid accumulation in macrophage was assessed by high-performance liquid chromatography and Oil red O staining. RNA immunoprecipitation and RNA pull-down assay were performed to verify the interaction between LEENE and FoxO1 protein. Atherosclerotic lesions were analyzed using HE, Oil red O and Masson staining. Our results showed that TNFAIP1 was significantly increased in THP-1 macrophages loaded with oxidized low-density lipoprotein. Knockdown of TNFAIP1 enhanced LEENE expression, promoted the direct interaction of LEENE with FoxO1 protein, stimulated FoxO1 protein degradation through the proteasome pathway, induced ABCA1 transcription, and finally suppressed lipid accumulation in THP-1 macrophage-derived foam cells. TNFAIP1 knockdown also up-regulated ABCA1 expression, improved plasma lipid profiles, enhanced the efficiency of reverse cholesterol transport and attenuated lesion area in apoE-/- mice. Taken together, these results provide the first direct evidence that TNFAIP1 aggravates atherosclerosis by promoting macrophage lipid accumulation via the LEENE/FoxO1/ABCA1 signaling pathway. TNFAIP1 may represent a promising therapeutic target for atherosclerotic cardiovascular disease.
RÉSUMÉ
(1) Background: Hypertension is a complex, multifactorial disease that is caused by genetic and environmental factors. Apart from genetic predisposition, the mechanisms involved in this disease have yet to be fully understood. We previously reported that LEENE (lncRNA enhancing endothelial nitric oxide expression, transcribed from LINC00520 in the human genome) regulates endothelial cell (EC) function by promoting the expression of endothelial nitric oxide synthase (eNOS) and vascular growth factor receptor 2 (VEGFR2). Mice with genetic deletion of the LEENE/LINC00520 homologous region exhibited impaired angiogenesis and tissue regeneration in a diabetic hindlimb ischemia model. However, the role of LEENE in blood pressure regulation is unknown. (2) Methods: We subjected mice with genetic ablation of leene and wild-type littermates to Angiotensin II (AngII) and monitored their blood pressure and examined their hearts and kidneys. We used RNA-sequencing to identify potential leene-regulated molecular pathways in ECs that contributed to the observed phenotype. We further performed in vitro experiments with murine and human ECs and ex vivo experiments with murine aortic rings to validate the select mechanism. (3) Results: We identified an exacerbated hypertensive phenotype of leene-KO mice in the AngII model, evidenced by higher systolic and diastolic blood pressure. At the organ level, we observed aggravated hypertrophy and fibrosis in the heart and kidney. Moreover, the overexpression of human LEENE RNA, in part, restored the signaling pathways impaired by leene deletion in murine ECs. Additionally, Axitinib, a tyrosine kinase inhibitor that selectively inhibits VEGFR suppresses LEENE in human ECs. (4) Conclusions: Our study suggests LEENE as a potential regulator in blood pressure control, possibly through its function in ECs.