Over-expression of microRNA-494 up-regulates hypoxia-inducible factor-1 alpha expression via PI3K/Akt pathway and protects against hypoxia-induced apoptosis

Abstract

BackgroundHypoxia-inducible factor-1 alpha (HIF-1α) is one of the key regulators of hypoxia/ischemia. MicroRNA-494 (miR-494) had cardioprotective effects against ischemia/reperfusion (I/R)-induced injury, but its functional relationship with HIF-1α was unknown. This study was undertaken to determine if miR-494 was involved in the induction of HIF-1α.ResultsQuantitative RT-PCR showed that miR-494 was up-regulated to peak after 4 hours of hypoxia in human liver cell line L02. To investigate the role of miR-494, cells were transfected with miR-494 mimic or miR-negative control, followed by incubation under normoxia or hypoxia. Our results indicated that overexpression of miR-494 significantly induced the expression of p-Akt, HIF-1α and HO-1 determined by qRT-PCR and western blot under normoxia and hypoxia, compared to negative control (p < 0.05). While LY294002 treatment markedly abolished miR-494-inducing Akt activation, HIF-1α and HO-1 increase under both normoxic and hypoxic conditions (p < 0.05). Moreover, apoptosis detection using Annexin V indicated that overexpression of miR-494 significantly decreased hypoxia-induced apoptosis in L02 cells, compared to control (p < 0.05). MiR-494 overexpression also decreased caspase-3/7 activity by 1.27-fold under hypoxia in L02 cells.ConclusionsOverexpression of miR-494 upregulated HIF-1α expression through activating PI3K/Akt pathway under both normoxia and hypoxia, and had protective effects against hypoxia-induced apoptosis in L02 cells. Thus, these findings suggested that miR-494 might be a target of therapy for hepatic hypoxia/ischemia injury.

Characteristic MicroRNA Expression Induced by δ-Opioid Receptor Activation in the Rat Liver Under Prolonged Hypoxia

“…Some studies show that miR-125a-5p prompted the activation and proliferation of hepatic stellate cell by partially down-regulating FIH1 in liver fibrosis [15], and miR-133a-5p was protective against hypoxia/reoxygenation (H/R) injury in vitro by targeting MAPK6 in hepatocytes [56]. Moreover, miR-146a could ameliorate liver hypoxia/reoxygenation injury in vitro by directly suppressing IRAK1 and TRAF6 [12] and miR-494 was protective against hypoxia-induced apoptosis in liver through HIF-1α upregulation by activating PI3K/ Akt pathway [14]. In addition, there is accumulating evidence suggesting that many other miRNAs are involved in liver reactions to hypoxic stress, such as miR-150 downregulation under hypoxia by targeting VEGF-A and HIF1α during liver regeneration [16, 57], miR-192-5p upregulation in hepatocyte injury [13] and increased miR-462/731 cluster in the hypoxia-exposed liver of Megalobrama amblycephala [58] and zebrafish [59].…”

“…For example, miR-146a attenuates hypoxia/reoxygenation injury in vitro by directly suppressing IRAK1 and TRAF6 in liver [12] and miR-192-5p protects liver cell from hepatic injury induced by oxidative stress by targeting Zeb2 [13]. Also, miR-494 protects against hypoxia-induced apoptosis by upregulating HIF1α expression through activating PI3K/Akt pathway [14]. Moreover, miR-125a-5p prompts the activation and proliferation of hepatic stellate cells by targeting FIH1 [15], while miR-150 is involved in liver regeneration by targeting VEGF-A [16].…”

Systematic review with meta-analysis: HIF-1α attenuates liver ischemia–reperfusion injury

“…Nine in vitro cell culture studies were reported using various cell lines. Oxygen concentrations for in vitro hypoxia were set as 1% in 7 studies [14,[21][22][23][24]40,41], 0% in one study [8], and 1% or 0.1% in one study [25]. In animal hypoxia models, oxygen concentration was varied from 0% to 21% (asphyxia, hypoxia, and normoxia) with time spans from acute hypoxia to tolerant hypoxia.…”

HIF-1α-induced microRNA-210 reduces hypoxia-induced osteoblast MG-63 cell apoptosis

“…24) And overexpression of microRNA-494 upregulates HIF-1α expression via PI3 K/Akt pathway and protects against hypoxia-induced apoptosis. 25) microRNA-210 is widely induced by hypoxia in various types of cells, such as cardiomyocytes, 26) keratinocyte 27) , and other cells. microRNA-210 has been indicated to exert neuroprotective effects against oxygen-glucose deprivation through apoptosis inhibition in PC12 cells, 28) and to induce angiogenesis and neurogenesis in the normal adult mouse brain.…”