Apelin-13Induces Autophagy Of HepG2Cells Effects On The Expression Of ERK1/2and Beclin1

Objective:This study is to determined the effect of Apelin-13on autophagy in HepG2cellline effects on the expression of ERK1/2and Beclin1, In this study, the effects ofApelin-13on autophagy in HepG2cells are also investigated.Methods:1.Cells of HepG2were treated with Apelin-13at final concentrations are①0μmol/L（control）,②0.0001μmol/L,③0.001μmol/L,④0.01μmol/L,⑤0.1μmol/Lfor24h. And another concentration are①10%FBS（control）,②Apelin-13（0.1μmol/L）,③Apelin-13（0.1μmol/L）+PD98059（10μmol/L）,④PD98059（10μmol/L），⑤DMSO(solvent).The expression levels of ERK1/2、 ERK1/2phosphorylation (pERK1/2), and Beclin1protein were detected by Western Blotanalysis.2.Expressions of ERK1/2、pERK1/2and Beclin1proteins were detected byWestern blot in all groups.3.The expression of Beclin1mRNA has been determined by RT-PCR in allgroups.4.The autophagy was observed after monodansy1cadaverin (MDC) staining ineach group.Results:1.The relative expression level of pERK1/2in cells treated with10%FBS,0.0001μmol/l,0.001μmol/l,0.01μmol/l and0.1μmol/l Apelin-13were0.445±0.021,0.764±0.013,0.857±0.018,0.906±0.072, and1.019±0.041, respectively.Statistically, after Apelin-13treatment, expression levels of pERK1/2at concentrations of0.0001μmol/l,0.001μmol/l, the group of0.01μmol/l and0.1μmol/l which were significantly higher than that in the negative control group (P<0.05)，the relative expression levels of Beclin1protein were0.354±0.010,0.734±0.017,1.080±0.068,1.092±0.014, and1.168±0.024, respectively，Cells treatedwith Apelin-13which compared with cells treated with10%FBS had significantlyhigher levels of Beclin1expression (P<0.05). Apelin-13has no-effective for ERK1/2.Beclin1mRNA level was0.466±0.095in cells treated with10%FBS. And BeclinmRNA levels were0.737±0.038,1.246±0.038,1.370±0.039and1.522±0.034incells treated with0.0001μmol/l,0.001μmol/l,0.01μmol/l and0.1μmol/l Apelin-13.Statistically, there were significantly higher levels of Beclin1mRNA in cells treatedwith Apelin-13than that in cells treated with10%FBS (P<0.05). With the increasingof Apelin-13concentration, more blue and green luminescence autophagosomes weredetected in HepG2cells under inverted fluorescence microscopy.2.After treated HepG2cells with Apelin-13inhibitor PD98059, the relativeexpression levels of Beclin1protein were1.009±0.045、1.590±0.010、1.155±0.039、0.889±0.024、1.141±0.018； and pERK1/2were1.169±0.010、1.511±0.044、1.1435±0.041、0.955±0.023、1.087±0.053.Both compared with others treated, Aftertreated with Apelin-13and PD98059, Beclin1expression level of cells weresignificantly higher (P<0.01).The relative expression levels of Beclin1mRNA were1.068±0.056、1.582±0.017、1.132±0.028、0.917±0.023、1.133±0.008, compared withothers treated, cells treated with Apelin-13and PD98059had significantly higherlevels of Beclin1expression (P<0.01). In contrast, in PD98059-treated cells,autophagosomes in HepG2decreased significantly than Apelin-13-treated cells.Conclusion:1.Apelin-13may induce the phosphorylation of ERK1/2in HepG2cells andup-regulating the expression of Beclin1. 2.Promote the expression of Beclin1may up-regulating the expression ofautophagosome in HepG2cells.