title: PCSK9 siRNA inhibits HUVEC apoptosis induced by ox-LDL via Bcl/Bax-caspase9-caspase3 pathway.
abstract: This paper investigated the effects of ox-LDL on PCSK9, and the molecular mechanisms of PCSK9 siRNA-inhibited apoptosis induced by ox-LDL in human umbilical vein endothelial cells (HUVECs), to clarify the role of PCSK9 in atherosclerogenesis. HUVECs were incubated with ox-LDL for 24 h. The apoptosis was observed by Hoechst 33258 staining. The expression of PCSK9, LOX-1 mRNAs and proteins was detected by RT-PCR, western blot, respectively. The PCSK9 siRNAs labeled with fluorescence were transfected into HUVECs by Lipofectamine 2000. After transfection for 24 h, cells were treated with ox-LDL for 24 h, HUVECs apoptosis transfected siRNA was detected by Hoechst 33258 staining and flow cytometer. The expression of Bcl-2, Bax, caspase3, 8, 9 was detected by western blot. The activity of caspase3, 9 was detected by kits. Our results showed that apoptosis of HUVECs and the expressions of PCSK9 and LOX-1 were upregulated secondary to induction by ox-LDL in a concentration-dependent manner. However, ox-LDL-induced HUVEC apoptosis and PCSK9 expression, but not LOX-1 expression, were significantly reduced by PCSK9 siRNA. These results demonstrate a linkage between HUVEC apoptosis and PCSK9 expression. Furthermore, we detected the possible pathway involved in apoptotic regulation by PCSK9 siRNA; our results showed that the expression of Bcl-2 decreased, whereas that of Bax increased. In addition, ox-LDL enhanced the activity of caspase9 and then caspase3. Pretreatment of HUVECs with PCSK9 siRNA blocked these effects of ox-LDL. These findings suggest that ox-LDL-induced HUVECs apoptosis could be inhibited by PCSK9 siRNA, in which Bcl/Bax-caspase9-caspase3 pathway maybe was involved through reducing the Bcl-2/Bax ratio and inhibited the activation of both caspase9 and 3.
authors.affiliation: Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang, 421001, Hunan, China.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Wu
authors.forename: Zhi-Han
authors.initials: ZH
authors.lastname: Tang
authors.forename: Lu
authors.initials: L
authors.lastname: Jiang
authors.forename: Xue-Fei
authors.initials: XF
authors.lastname: Li
authors.forename: Zhi-Sheng
authors.initials: ZS
authors.lastname: Jiang
authors.forename: Lu-Shan
authors.initials: LS
authors.lastname: Liu
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000187:drug effects* / Q000502:physiology; D053148:Caspase 3; D053453:Caspase 9; D002478:Cells, Cultured; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D008077:Lipoproteins, LDL / Q000502:physiology*; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases / Q000037:antagonists & inhibitors / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering / Q000494:pharmacology*; D012697:Serine Endopeptidases / Q000235:genetics*; D015398:Signal Transduction; D051028:bcl-2-Associated X Protein
chemical_list: D051017:Apoptosis Regulatory Proteins; D008077:Lipoproteins, LDL; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D051028:bcl-2-Associated X Protein; C099252:oxidized low density lipoprotein; C472125:PCSK9 protein, human; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; D053148:Caspase 3; D053453:Caspase 9