MicroRNA-122 aggravates angiotensin II-mediated apoptosis and autophagy imbalance in rat aortic adventitial fibroblasts via the modulation of SIRT6-elabela-ACE2 signaling

Abstract

Abnormal aortic adventitial fibroblasts (AFs) play essential roles in the development of vascular remodeling and disorders. Previous studies revealed that microRNA-122 (miR-122) levels were elevated in the aortic adventitia of hypertensive rats with vascular injury. Here, we aim to evaluate the biological effects and underlying mechanisms of miR-122 in rat AFs. Exposure to angiotensin II (ATII) in rat AFs resulted in decreased levels of sirtuin 6 (SIRT6), elabela (ELA), and angiotensin-converting enzyme 2 (ACE2). Additionally, stimulation with ATII contributed to a decline in autophagic flux and obvious increases in cellular migration, oxidative stress, and apoptosis, which were exacerbated by the transfection of miR-122-5p mimic but were rescued by miR-122-5p inhibitor, exogenous replenishment of ELA, and recombinant adeno-associated virus expressing SIRT6 (rAAV-SIRT6), respectively. Moreover, stimulation with miR-122-5p mimic led to a marked reduction in the levels of SIRT6 and ELA in rat AFs, which were elevated by stimulation with rAAV-SIRT6. Furthermore, miR-122-5p inhibitor-mediated pro-autophagic, anti-oxidant and anti-apoptotic effects in rat AFs were partially suppressed by 3-methyladenine, SIRT6 small interfering RNA (siRNA) and ELA siRNA, which were linked with the downregulation in the protein levels of LC3-II, beclin-1, and ACE2 and the upregulation of p62 expression and bax/bcl-2 ratio. Our findings indicated that miR-122-5p inhibition prevented ATII-mediated loss of autophagy, and the promotion of apoptosis and oxidative stress via activating the SIRT6-ELA-ACE2 signaling. MiR-122-5p may be a novel predictive biomarker of adventitial injury, and targeting the SIRT6-ELA-ACE2 signaling may have the potential therapeutic importance of controlling vascular remodeling and disorders.

Roles of MicroRNA-122 in Cardiovascular Fibrosis and Related Diseases

“…The promoter region of miR-122 is highly conserved and located approximately 5 kb upstream of the conserved stem-loop sequences in miR-122, which include large nuclear receptor factor-binding sequences, such as the TATA-box and CCAAT-box [8]. Notably, sirtuin 6 (SIRT6), a miR-122 target gene, is important regulator of cardiovascular fibrosis, remodeling and dysfunction [1]. Intriguingly, SIRT1, SIRT6, Apelin (APLN), Apelin receptor (APLNR) and forkhead box O3 (FOXO3) were identified as miR-122 target genes (Fig.…”

“…Both miR-122-3p and miR-122-5p are widely expressed in endothelial cells (ECs), cardiomyocytes (CMs), cardiac fibroblasts (CFs), adipocytes, vascular smooth muscle cells (VSMCs) and adventitial fibroblasts (AFs) in the cardiovascular system (Table 1; Fig. 3) [1,6,9,10]. Recently, administration of a miR-122 inhibitor was shown to reduce the key transforming growth factor-β (TGF-β)-induced fibrotic signaling pathway, promotes collagen synthesis and stimulates fibrinogenesis, consequently resulting in the accumulation of fibroblasts and extracellular matrix (ECM), in hypertension and cardiovascular diseases [2,3,9,11].…”

“…There-fore, miR-122 can cause cardiovascular fibrosis and heart dysfunction, ultimately resulting in hypertension, atherosclerosis, MI and HF. MI myocardial infarction, HF heart failure, ROS reactive oxygen species, LVFS left ventricular fractional shortening, LVEF left ventricular ejection fraction effects were associated with increased levels of miR-122-5p, and reduced levels of SIRT6, elabela (ELA), angiotensin-converting enzyme 2 (ACE2) and phosphorylated adenosine 5 '-monophosphate-activated protein kinase (AMPK) ( Table 1) [1,2,6]. In uric acid-treated HK-2 tubular epithelial cells, treatment with miR-122 mimics markedly increased NLRP3 inflammasome activation by increasing the levels of BRCA1/ BRCA2-containing complex 3 (Table 1) [12].…”

“…c The sequence of miR-122 is highly conserved in humans, mice and rats. FOXO3 forkhead box O3, SIRT1 sirtuin 1, SIRT6 sirtuin 6, APLN Apelin, APLNR Apelin receptor Table 1 The regulatory roles and underlying mechanisms of miR-122 in cardiovascular fibrosis, dysfunction and related diseases ACE2 angiotensin converting enzyme 2, AMPK adenosine 5′-monophosphate-activated protein kinase, AFs adventitial fibroblasts, CFs cardiofibroblasts, CKD chronic kidney disease, ERK extracellular regulated protein kinases, HF heart failure, KO knockout, SIRT6 sirtuin 6, ELA elabela, OGD oxygen-glucose deprivation, NLRP3 nod-like receptor protein 3, LGR4 leucine-rich repeat-containing G protein-coupled receptor 4, GSK-3β glycogen synthase kinase-3β antibody, PTEN gene of phosphate and tension homology deleted on chromosome ten, PI3K phosphatidylinositol 3-kinase, Akt serine/threonine protein kinase, CTGF connective tissue growth factor, mTOR mammalian target of rapamycin, NRVMs neonatal rat ventricular cardiomyocytes, TAC transverse aortic constriction, TGF-β1 transforming growth factor-β1, FOXO3 forkhead box O3, Bach-1 BTB and CNC homology 1, HO-1 heme oxygenase1, MCP-1 monocyte chemotactic protein 1, TNF-α tumor necrosis factor α, LAD left anterior descending artery, LVFS left ventricular fractional shortening, LVEF left ventricular ejection fraction, ROS reactive oxygen species marker of fibrosis and appears to stimulate the inflammation and oxidative stress in the heart, blood vessels and liver [1,6,8,11,15]. MiR-122 has been found to increased levels of the fibrotic factors collagen 1α1, collagen 1α2 and TGF-β1 and the proinflammatory factor monocyte chemoattractant protein-1 (MCP-1) [15].…”

“…Notably, miR-122 functions as a risk biomarker of cardiovascular fibrosis and appears to be a direct participant in the development of cardiovascular diseases, including hypertension, atherosclerosis, HF, myocardial infarction (MI) and atrial fibrillation ( Fig. 1) [1,[5][6][7][8][9]. In this review, we highlight the developments and latest advances concerning the biogenesis and biological effects of miR-122 signaling and the regulatory roles of miR-122 in cardiovascular fibrosis and dysfunction.…”