miR-223 reverses experimental pulmonary arterial hypertension

Abstract

nary arterial hypertension (PAH) is a devastating disease affecting lung vasculature. The pulmonary arteries become occluded due to increased proliferation and suppressed apoptosis of the pulmonary artery smooth muscle cells (PASMCs) within the vascular wall. It was recently shown that DNA damage could trigger this phenotype by upregulating poly(ADP-ribose)polymerase 1 (PARP-1) expression, although the exact mechanism remains unclear. In silico analyses and studies in cancer demonstrated that microRNA miR-223 targets PARP-1. We thus hypothesized that miR-223 downregulation triggers PARP-1 overexpression, as well as the proliferation/apoptosis imbalance observed in PAH. We provide evidence that miR-223 is downregulated in human PAH lungs, distal PAs, and isolated PASMCs. Furthermore, using a gain and loss of function approach, we showed that increased hypoxia-inducible factor 1␣, which is observed in PAH, triggers this decrease in miR-223 expression and subsequent overexpression of PARP-1 allowing PAH-PASMC proliferation and resistance to apoptosis. Finally, we demonstrated that restoring the expression of miR-223 in lungs of rats with monocrotaline-induced PAH reversed established PAH and provided beneficial effects on vascular remodeling, pulmonary resistance, right ventricle hypertrophy, and survival. We provide evidence that miR-223 downregulation in PAH plays an important role in numerous pathways implicated in the disease and restoring its expression is able to reverse PAH. miR-223; pulmonary hypertension; PARP-1; HIF-1␣; DNA damage PULMONARY ARTERIAL HYPERTENSION (PAH) is a serious condition characterized by obstruction of the precapillary pulmonary arterioles (PA) due to excessive vasoconstriction, inflammation, and imbalance between cells' proliferation and apoptosis within the arterial wall. This remodeling and obstruction of the PAs leads to increases in pulmonary vascular resistance, right ventricular (RV) failure, and death of patients. Despite recent therapeutic advances, most patients exhibit persistently poor exercise capacity and quality of life, with a 3-yr survival rate of 65% (12).Growing evidence underlines the importance of DNA damage in PAH etiology (9,19,23). Indeed, the sustained inflammation, RAGE expression (21), and metabolic stress (30) observed in PAH result in DNA damage-dependent activation of poly(ADP-ribose)polymerase 1 (PARP-1) in PA smooth muscle cells (PASMCs) of PAH patients (23). We recently showed that PARP-1 overexpression was responsible for enhanced PAH-PASMC proliferation and suppressed apoptosis (23). Nevertheless, the mechanisms that regulate this overexpression in PAH remain elusive.In cancer, PARP-1 expression is regulated by microRNA-223 (miR-223), a microRNA involved in DNA damage response (34). According to TargetScan 6.2, PARP-1 is in fact a predicted target of miR-223. Moreover, downregulation of miR-223 has been shown to mediate mechanical stretch-stimulated proliferation of vascular smooth muscle cells (33). Interestingly, Wang et al. (38) reported that miR-...

Implication of Inflammation and Epigenetic Readers in Coronary Artery Remodeling in Patients With Pulmonary Arterial Hypertension

“…We and others have described the implication of the receptor of advanced glycation endproducts, 2-4 the oncoprotein kinase Pim-1 3,5 and the transcription factor nuclear factor of activated T cells 6,7 in promoting proliferation in remodeling processes occurring in both VRD and PAH. In PAH patients' lung vasculature, these molecular actors are, at least in part, regulated by proinflammatory cytokines, alterations in the miR-223/DNA damage/ Poly[ADP-ribose] polymerase 1/miR-204 axis [8][9][10][11] and subsequent overexpression of the epigenetic reader bromodomain protein 4 (BRD4). 12 BRD4 functions as a scaffold for transcription factors at promoters and superenhancers, modulating the chromatin landscape and facilitating transcriptional activation of target genes.…”

Translational Advances in the Field of Pulmonary Hypertension.Translating MicroRNA Biology in Pulmonary Hypertension. It Will Take More Than “miR” Words

“…DNA damage is increased in circulating peripheral blood mononuclear cells, PAECs, and PASMCs (35,36). DNA damage was reported to down-regulate miR-223 in PAH-PASMCs (37). This down-regulation induced poly(ADPribose) polymerase (PARP)-1, which mediates the DNA damage response and contributes to DNA repair.…”

Bromodomain-Containing Protein 4

“…We measured spare respiratory capacity of cells to assess survival and their ability to respond to stress. 25 Medication not known … 3 (27) Values are mean±SD. Note that some patients take >1 type of medication.…”

“…All rats underwent closed-chest right heart catheterization to assess mean PA pressure (mPAP), RV systolic pressure, RV cardiac output, and total pulmonary resistance as previously described. 27 All hemodynamic measurements were performed blinded to the condition.…”