Hypoxia-Mediated Expression of 5-Lipoxygenase–Activating Protein Involves HIF-1α and NF-κB and MicroRNAs 135a and 199a-5p

Abstract

Hypoxia occurs in a number of pathological states, such as pulmonary, hematological, and cardiovascular disorders. In this study, we examined the molecular mechanism by which hypoxia contributes to increased leukotriene formation. Our studies showed hypoxia augmented the expression of 5-lipoxygenase activating protein (FLAP), a key enzyme in leukotriene formation, in both human pulmonary microvascular endothelial cells and a transformed human brain endothelial cell line. Hypoxia-induced FLAP mRNA expression involved activation of NADPH-oxidase, PI-3 kinase, mitogen-activated protein kinase, NF-κB, and hypoxia-inducible factor (HIF)-1α. Hypoxia-induced FLAP promoter activity was attenuated on mutation of hypoxia-response elements (HREs) and NF-κB binding motif in the FLAP promoter. Hypoxia also augmented binding of HIF-1α to HREs in FLAP promoter as demonstrated by EMSA with nuclear extracts. Furthermore, chromain immunoprecipitation analysis showed HIF-1α bound to HREs in native chromatin obtained from hypoxia-treated cells. Next, we examined the role of HIF-1α regulated microRNAs on FLAP expression. Our studies showed decreased expression of miR-135a and miR-199a-5p in response to hypoxia. However, overexpression of anti–miR-135a and anti–miR-199a-5p oligonucleotides led to a several fold increased FLAP mRNA and protein expression. These studies demonstrate for the first time that hypoxia-mediated FLAP expression is regulated by HREs and NF-κB site in its promoter, and negatively regulated by miR-135a and miR-199a-5p, which target the 3′-UTR of FLAP mRNA. An understanding of these regulatory pathways provides new avenues to ameliorate leukotriene formation and hence reactive airway disease, and inflammation in individuals who have sickle cell disease.

Peroxisome Proliferator-activated Receptor-α-mediated Transcription of miR-199a2 Attenuates Endothelin-1 Expression via Hypoxia-inducible Factor-1α

“…Hypoxia was also shown to regulate expression of several other miRNAs that post-transcriptionally modulate levels of a variety of mRNAs, including HIF-1␣ (40). Indeed, our studies demonstrated that hypoxia reduces miR-199a2 levels in endothelial cells, which is manifested by increased HIF-1␣ expression as previously shown (41). miR-199a2 is located within the DNM3os transcription unit.…”

MicroRNA-199a-5p Is Associated With Hypoxia-Inducible Factor-1α Expression in Lungs From Patients With COPD

“…We also show that the increased expression of these miRNA species was associated with impaired lung function, as assessed by FEV 1 % predicted. Because of reports demonstrating that the expression of the important transcription factor HIF-1 a was under the control of miRNA, 19,26,27 we conducted experiments in HPMVECs to investigate interac tions between miRNA and HIF-1 a expression. In view of other data demonstrating increased p53 expres sion in COPD/emphysema lung tissues 14,20 and in view of the established interaction between p53 and HIF-1 a protein expression, 28,29 we also examined the interaction between p53 and HIF-1 a expression in HPMVECs.…”

“…[15][16][17] Rane et al 18 recently reported that constitutive active adenovirus AKT gene transfection caused the decrease of miR-199a-5p expression in neonatal cardiac myocytes, which are known to control HIF-1 a protein expression. 19 Further, it has been reported that replenishing of miR-199a-5p also regulates the hypoxic stabilization of p53. 18 The p53 protein expression is increased in tissues from patients with COPD/emphysema, 14,20 and p53 regulates miR-34a expression in response to DNA damage.…”

“…30 In this present data set, there was only a statistical trend for a decreased lung tissue HIF-1 a mRNA expression ( Fig 1A ). Although a global miRNA expression analysis of the tissues is feasible, we focused on the analysis of miR-34a and miR-199a-5p; these miRNA have previously been shown to be involved in the control of HIF-1 a and VEGF protein expression 19,26 or were shown to be controlled by p53. 21,22 We have previously proposed, based on the expression analysis of lung tissues from patients with COPD, that the reduction of lung tissue histone deacetylase 2 expression may be related to the regulation of both p53 and HIF-1 a 14 and to lung cell apoptosis and maintenance of pulmonary microvessels.…”

Chemotherapy-induced modification of microRNA expression in esophageal cancer

“…Analysis of predicted targets of these miRNAs highlighted molecular networks which include functions such as 'Cell death', 'Cell cycle', 'Cellular growth and proliferation', 'DNA replication, recombination, and repair' and 'Drug metabolism', and this suggests that the identified changes in miRNA expression are consistent with a biological effect in the cells responding to the cytotoxic agents. Deregulation or stable expression has been reported for several of the identified miRNAs, including miR-342-3p, miR-425 or miR-455-3p, in inflammatory breast cancer, multiple myeloma, acute promyelocytic leukemia, glioblastoma, colorectal cancer, malignant mesothelioma or hepatocellular carcinoma, and they seem to play a role in cancer development by affecting proliferation, cell cycle control, migration, angiogenesis, differentiation, invasion and hypoxia (miR-199a-5p) (15)(16)(17)(18)(19)(20)(21)(22)(23). More interestingly, some of the identified miRNAs or members of their families (namely miR-342, miR-758, miR519c and miR-455-3p) were found to be deregulated in drug resistant cancer cell lines, and ectopic modulation of miR-519c and miR-455-3p expression has been shown to impact on the sensitivity to mitoxantrone and temozolomide treatment respectively.…”