Activation of NF-E2-related factor-2 reverses biochemical dysfunction of endothelial cells induced by hyperglycemia linked to vascular disease.
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.


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.
Xue
Mingzhan
M
Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, University Hospital, Coventry, UK.
Qian
Qingwen
Q
Adaikalakoteswari
Antonysunil
A
Rabbani
Naila
N
Babaei-Jadidi
Roya
R
Thornalley
Paul J
PJ
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005434:Flow Cytometry; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism / Q000503:physiopathology; D015151:Immunoblotting; D017879:Isothiocyanates; D018613:Microscopy, Confocal; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013454:Sulfoxides; D013861:Thiocyanates / Q000494:pharmacology*; D014162:Transfection; D014174:Transketolase / Q000235:genetics / Q000378:metabolism
D017879:Isothiocyanates; D051267:NF-E2-Related Factor 2; D034741:RNA, Small Interfering; D013454:Sulfoxides; D013861:Thiocyanates; D014174:Transketolase; C016766:sulforaphane