PMC, a potent hydrophilic α-tocopherol derivative, inhibits NF-κB activation via PP2A but not IκBα-dependent signals in vascular smooth muscle cells

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Abstract

The hydrophilic α-tocopherol derivative, 2,2,5,7,8-pentamethyl-6-hydroxychromane (PMC), is a promising alternative to vitamin E in clinical applications. Critical vascular inflammation leads to vascular dysfunction and vascular diseases, including atherosclerosis, hypertension and abdominal aortic aneurysms. In this study, we investigated the mechanisms of the inhibitory effects of PMC in vascular smooth muscle cells (VSMCs) exposed to pro-inflammatory stimuli, lipopolysaccharide (LPS) combined with interferon (IFN)-γ. Treatment of LPS/IFN-γ-stimulated VSMCs with PMC suppressed the expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase-9 in a concentration-dependent manner. A reduction in LPS/IFN-γ-induced nuclear factor (NF)-κB activation was also observed in PMC-treated VSMCs. The translocation and phosphorylation of p65, protein phosphatase 2A (PP2A) inactivation and the formation of reactive oxygen species (ROS) were significantly inhibited by PMC in LPS/IFN-γ-activated VSMCs. However, neither IκBα degradation nor IκB kinase (IKK) or ribosomal s6 kinase-1 phosphorylation was affected by PMC under these conditions. Both treatments with okadaic acid, a PP2A-selective inhibitor, and transfection with PP2A siRNA markedly reversed the PMC-mediated inhibition of iNOS expression, NF-κB-promoter activity and p65 phosphorylation. Immunoprecipitation analysis of the cellular extracts of LPS/IFN-γ-stimulated VSMCs revealed that p65 colocalizes with PP2A. In addition, p65 phosphorylation and PP2A inactivation were induced in VSMCs by treatment with H2O2, but neither IκBα degradation nor IKK phosphorylation was observed. These results collectively indicate that the PMC-mediated inhibition of NF-κB activity in LPS/IFN-γ-stimulated VSMCs occurs through the ROS-PP2A-p65 signalling cascade, an IKK-IκBα-independent mechanism. Therapeutic interventions using PMC may therefore be beneficial for the treatment of vascular inflammatory diseases.

Original languageEnglish
Pages (from-to)1278-1289
Number of pages12
JournalJournal of Cellular and Molecular Medicine
Volume18
Issue number7
DOIs
Publication statusPublished - 2014

Fingerprint

Protein Phosphatase 2
Tocopherols
Vascular Smooth Muscle
Smooth Muscle Myocytes
Interferons
Lipopolysaccharides
Phosphorylation
Nitric Oxide Synthase Type II
Vascular Diseases
Blood Vessels
Reactive Oxygen Species
Ribosomal Protein S6 Kinases
Okadaic Acid
Matrix Metalloproteinase 9
Abdominal Aortic Aneurysm
Vitamin E
Immunoprecipitation
Small Interfering RNA
Transfection
Atherosclerosis

Keywords

  • NF-κB
  • PMC
  • PP2A
  • ROS
  • Vascular inflammation

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Medicine

Cite this

@article{26ad6975ba364a5683e1113041f74e44,
title = "PMC, a potent hydrophilic α-tocopherol derivative, inhibits NF-κB activation via PP2A but not IκBα-dependent signals in vascular smooth muscle cells",
abstract = "The hydrophilic α-tocopherol derivative, 2,2,5,7,8-pentamethyl-6-hydroxychromane (PMC), is a promising alternative to vitamin E in clinical applications. Critical vascular inflammation leads to vascular dysfunction and vascular diseases, including atherosclerosis, hypertension and abdominal aortic aneurysms. In this study, we investigated the mechanisms of the inhibitory effects of PMC in vascular smooth muscle cells (VSMCs) exposed to pro-inflammatory stimuli, lipopolysaccharide (LPS) combined with interferon (IFN)-γ. Treatment of LPS/IFN-γ-stimulated VSMCs with PMC suppressed the expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase-9 in a concentration-dependent manner. A reduction in LPS/IFN-γ-induced nuclear factor (NF)-κB activation was also observed in PMC-treated VSMCs. The translocation and phosphorylation of p65, protein phosphatase 2A (PP2A) inactivation and the formation of reactive oxygen species (ROS) were significantly inhibited by PMC in LPS/IFN-γ-activated VSMCs. However, neither IκBα degradation nor IκB kinase (IKK) or ribosomal s6 kinase-1 phosphorylation was affected by PMC under these conditions. Both treatments with okadaic acid, a PP2A-selective inhibitor, and transfection with PP2A siRNA markedly reversed the PMC-mediated inhibition of iNOS expression, NF-κB-promoter activity and p65 phosphorylation. Immunoprecipitation analysis of the cellular extracts of LPS/IFN-γ-stimulated VSMCs revealed that p65 colocalizes with PP2A. In addition, p65 phosphorylation and PP2A inactivation were induced in VSMCs by treatment with H2O2, but neither IκBα degradation nor IKK phosphorylation was observed. These results collectively indicate that the PMC-mediated inhibition of NF-κB activity in LPS/IFN-γ-stimulated VSMCs occurs through the ROS-PP2A-p65 signalling cascade, an IKK-IκBα-independent mechanism. Therapeutic interventions using PMC may therefore be beneficial for the treatment of vascular inflammatory diseases.",
keywords = "NF-κB, PMC, PP2A, ROS, Vascular inflammation",
author = "Hsieh, {Cheng Ying} and George Hsiao and Hsu, {Ming Jen} and Wang, {Yi Hsuan} and Sheu, {Joen Rong}",
year = "2014",
doi = "10.1111/jcmm.12277",
language = "English",
volume = "18",
pages = "1278--1289",
journal = "Journal of Cellular and Molecular Medicine",
issn = "1582-1838",
publisher = "Wiley-Blackwell",
number = "7",

}

TY - JOUR

T1 - PMC, a potent hydrophilic α-tocopherol derivative, inhibits NF-κB activation via PP2A but not IκBα-dependent signals in vascular smooth muscle cells

AU - Hsieh, Cheng Ying

AU - Hsiao, George

AU - Hsu, Ming Jen

AU - Wang, Yi Hsuan

AU - Sheu, Joen Rong

PY - 2014

Y1 - 2014

N2 - The hydrophilic α-tocopherol derivative, 2,2,5,7,8-pentamethyl-6-hydroxychromane (PMC), is a promising alternative to vitamin E in clinical applications. Critical vascular inflammation leads to vascular dysfunction and vascular diseases, including atherosclerosis, hypertension and abdominal aortic aneurysms. In this study, we investigated the mechanisms of the inhibitory effects of PMC in vascular smooth muscle cells (VSMCs) exposed to pro-inflammatory stimuli, lipopolysaccharide (LPS) combined with interferon (IFN)-γ. Treatment of LPS/IFN-γ-stimulated VSMCs with PMC suppressed the expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase-9 in a concentration-dependent manner. A reduction in LPS/IFN-γ-induced nuclear factor (NF)-κB activation was also observed in PMC-treated VSMCs. The translocation and phosphorylation of p65, protein phosphatase 2A (PP2A) inactivation and the formation of reactive oxygen species (ROS) were significantly inhibited by PMC in LPS/IFN-γ-activated VSMCs. However, neither IκBα degradation nor IκB kinase (IKK) or ribosomal s6 kinase-1 phosphorylation was affected by PMC under these conditions. Both treatments with okadaic acid, a PP2A-selective inhibitor, and transfection with PP2A siRNA markedly reversed the PMC-mediated inhibition of iNOS expression, NF-κB-promoter activity and p65 phosphorylation. Immunoprecipitation analysis of the cellular extracts of LPS/IFN-γ-stimulated VSMCs revealed that p65 colocalizes with PP2A. In addition, p65 phosphorylation and PP2A inactivation were induced in VSMCs by treatment with H2O2, but neither IκBα degradation nor IKK phosphorylation was observed. These results collectively indicate that the PMC-mediated inhibition of NF-κB activity in LPS/IFN-γ-stimulated VSMCs occurs through the ROS-PP2A-p65 signalling cascade, an IKK-IκBα-independent mechanism. Therapeutic interventions using PMC may therefore be beneficial for the treatment of vascular inflammatory diseases.

AB - The hydrophilic α-tocopherol derivative, 2,2,5,7,8-pentamethyl-6-hydroxychromane (PMC), is a promising alternative to vitamin E in clinical applications. Critical vascular inflammation leads to vascular dysfunction and vascular diseases, including atherosclerosis, hypertension and abdominal aortic aneurysms. In this study, we investigated the mechanisms of the inhibitory effects of PMC in vascular smooth muscle cells (VSMCs) exposed to pro-inflammatory stimuli, lipopolysaccharide (LPS) combined with interferon (IFN)-γ. Treatment of LPS/IFN-γ-stimulated VSMCs with PMC suppressed the expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase-9 in a concentration-dependent manner. A reduction in LPS/IFN-γ-induced nuclear factor (NF)-κB activation was also observed in PMC-treated VSMCs. The translocation and phosphorylation of p65, protein phosphatase 2A (PP2A) inactivation and the formation of reactive oxygen species (ROS) were significantly inhibited by PMC in LPS/IFN-γ-activated VSMCs. However, neither IκBα degradation nor IκB kinase (IKK) or ribosomal s6 kinase-1 phosphorylation was affected by PMC under these conditions. Both treatments with okadaic acid, a PP2A-selective inhibitor, and transfection with PP2A siRNA markedly reversed the PMC-mediated inhibition of iNOS expression, NF-κB-promoter activity and p65 phosphorylation. Immunoprecipitation analysis of the cellular extracts of LPS/IFN-γ-stimulated VSMCs revealed that p65 colocalizes with PP2A. In addition, p65 phosphorylation and PP2A inactivation were induced in VSMCs by treatment with H2O2, but neither IκBα degradation nor IKK phosphorylation was observed. These results collectively indicate that the PMC-mediated inhibition of NF-κB activity in LPS/IFN-γ-stimulated VSMCs occurs through the ROS-PP2A-p65 signalling cascade, an IKK-IκBα-independent mechanism. Therapeutic interventions using PMC may therefore be beneficial for the treatment of vascular inflammatory diseases.

KW - NF-κB

KW - PMC

KW - PP2A

KW - ROS

KW - Vascular inflammation

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U2 - 10.1111/jcmm.12277

DO - 10.1111/jcmm.12277

M3 - Article

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AN - SCOPUS:84905045229

VL - 18

SP - 1278

EP - 1289

JO - Journal of Cellular and Molecular Medicine

JF - Journal of Cellular and Molecular Medicine

SN - 1582-1838

IS - 7

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