Activation of NF-E2–Related Factor-2 Reverses Biochemical Dysfunction of Endothelial Cells Induced by Hyperglycemia Linked to Vascular Disease

  1. Mingzhan Xue1,
  2. Qingwen Qian2,
  3. Antonysunil Adaikalakoteswari1,
  4. Naila Rabbani12,
  5. Roya Babaei-Jadidi2 and
  6. Paul J. Thornalley12
  1. 1Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, University Hospital, Coventry, U.K
  2. 2Department of Biological Sciences, University of Essex, Central Campus, Wivenhoe Park, Colchester, Essex, U.K
  1. Corresponding author: Paul J. Thornalley, p.j.thornalley{at}warwick.ac.uk

Abstract

OBJECTIVE—Sulforaphane is an activator of transcription factor NF-E2–related factor-2 (nrf2) that regulates gene expression through the promoter antioxidant response element (ARE). Nrf2 regulates the transcription of a battery of protective and metabolic enzymes. The aim of this study was to assess whether activation of nrf2 by sulforaphane in human microvascular endothelial cells prevents metabolic dysfunction in hyperglycemia.

RESEARCH DESIGN AND METHODS—Human microvascular HMEC-1 endothelial cells were incubated in low and high glucose concentrations (5 and 30 mmol/l, respectively), and activation of nrf2 was assessed by nuclear translocation. The effects of sulforaphane on multiple pathways of biochemical dysfunction, increased reactive oxygen species (ROS) formation, hexosamine pathway, protein kinase C (PKC) pathway, and increased formation of methylglyoxal were assessed.

RESULTS—Activation of nrf2 by sulforaphane induced nuclear translocation of nrf2 and increased ARE-linked gene expression, for example, three- to fivefold increased expression of transketolase and glutathione reductase. Hyperglycemia increased the formation of ROS—an effect linked to mitochondrial dysfunction and prevented by sulforaphane. ROS formation was increased further by knockdown of nrf2 and transketolase expression. This also abolished the counteracting effect of sulforaphane, suggesting mediation by nrf2 and related increase of transketolase expression. Sulforaphane also prevented hyperglycemia-induced activation of the hexosamine and PKC pathways and prevented increased cellular accumulation and excretion of the glycating agent methylglyoxal.

CONCLUSIONS—We conclude that activation of nrf2 may prevent biochemical dysfunction and related functional responses of endothelial cells induced by hyperglycemia in which increased expression of transketolase has a pivotal role.

Footnotes

  • Published ahead of print at http://diabetes.diabetesjournals.org on 15 July 2008.

    Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.

    The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

    • Accepted July 1, 2008.
    • Received July 19, 2006.
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  1. Diabetes vol. 57 no. 10 2809-2817
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