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| Pollen Typhae Total Flavone Inhibits Endoplasmic Reticulum Stress-Induced Apoptosis in Human Aortic-Vascular Smooth Muscle Cells through Down-Regulating PERK-eIF2α -ATF4-CHOP Pathway |
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| KeyWord:Pollen Typhae total flavone, endoplasmic reticulum stress, protein kinase RNA-like endoplasmic reticulum kinase-eukaryotic translation initiation factor 2α -activating transcription factor 4-CCAAT/enhancer binding protein homologous protein pathway, apoptosis, vulnerable atherosclerotic plaque |
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| Abstract: |
| Objective: To test the hypothesis that the inhibition of endoplasmic reticulum (ER) stress-induced apoptosis in oxidized low-density lipoproteins (ox-LDL)-induced human aortic-vascular smooth muscle cells (HA-VSMCs) was associated with suppression of the protein kinase RNA-like ER kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α )-activating transcription factor 4 (ATF4)-CCAAT/enhancer binding protein homologous protein (CHOP) signaling pathway by Pollen Typhae total flavone (PTF). Methods: Primary HA-VSMCs were cultured and identified. The cultured HA-VSMCs were randomized into 5 groups, including a normal control group, an ox-LDL group (70 μ g/mL high ox-LDL), an HPTF group (70 μ g/mL high ox-LDL+500 μ g/mL PTF), an MPTF group (70 μ g/mL high ox-LDL+250 μ g/mL PTF), and a LPTF group (70 μ g/mL high ox-LDL+100 μ g/mL PTF) in the first part; and a normal control group, an ox-LDL group (70 μ g/mL high ox-LDL), an MPTF group (70 μ g/mL high ox-LDL+250 μ g/mL PTF), a shRNA group (transducted with PERK shRNA lentiviral particles), a scramble shRNA group (transducted with control shRNA lentiviral particles), an MPTF+ox-LDL+shRNA group (250 μ g/mL PTF+70 μ g/mL high ox-LDL+PERK shRNA lentiviral particles) and an ox-LDL+shRNA group (70 μ g/mL high ox-LDL+PERK shRNA lentiviral particles) in the second part. The protein expression levels of ER-associated apoptosis proteins were detected by Western blot, and their mRNA expression levels were detected by quantitative real-time reverse transcription-polymerase chain reaction. The 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay was applied to test cell viability, and the level of apoptosis was monitored by flow cytometry. Results: The MTT assay and flow cytometry showed that the ox-LDL group had a significant increase in apoptosis, which was attenuated in PTF treatment groups and shRNA groups. Moreover, the ox-LDL group had increased protein and mRNA levels of binding immunoglobulin protein and ER-associated apoptosis proteins, such as PERK, eIF2α , ATF4 and CHOP, which were attenuated in PTF treatment groups and shRNA groups. Conclusions: The apoptosis induced by ox-LDL had a strong relation to ER stress. The protective effect of PTF on ER stress induced apoptosis was associated with inhibition of the PERK-eIF2α -ATF4-CHOP pathway, which might be a potential therapeutic strategy for enhancing the stability of atherosclerotic plaques. |
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