Pivotal role of JNK-dependent FOXO1 activation in downregulation of kallistatin expression by oxidative stress.
Oxidative stress has been shown to suppress endothelial nitric oxide synthase expression through activation of the transcription factor forkhead box O 1 (FOXO1) in cultured endothelial cells. We previously reported that circulating kallistatin levels are markedly reduced in rats with chronic oxidative organ damage. In this study, we investigated the potential role of oxidative stress in suppression of kallistatin expression via FOXO1 activation. In Dahl salt-sensitive (DSS) rats, we found that high salt intake induced a time-dependent correlation of increased thiobarbituric acid reactive substances (TBARS, an indicator of lipid peroxidation) with reduced serum kallistatin levels. Moreover, salt loading provoked an elevation of in situ aortic superoxide formation in association with reduced kallistatin levels. Expression of kallistatin was identified in cultured endothelial cells by immunocytochemistry and flow cytometry; however, H(2)O(2) dose-dependently lowered kallistatin mRNA and protein levels as determined by real-time PCR and Western blot, respectively. Downregulation of kallistatin synthesis by oxidative stress was restored by knockdown of FOXO1 expression with small-interfering RNA. H(2)O(2) rapidly induced FOXO1 nuclear translocation, but the effect was blocked by c-Jun NH(2)-terminal kinase (JNK) inhibitor. Inhibition of JNK by pharmacological inhibitor or small-interfering RNA reversed H(2)O(2)'s effect on kallistatin expression in endothelial cells. This study demonstrates that an inverse relationship exists between oxidative stress and kallistatin levels in the circulation and blood vessels and that kallistatin expression is negatively regulated by oxidative stress via JNK-dependent FOXO1 activation in cultured endothelial cells.
Shen
Bo
B
Dept. of Biochemistry and Molecular Biology, Medical Univ. of South Carolina, Charleston, 29425-2211, USA.
Chao
Lee
L
Chao
Julie
J
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D008297:Male; D023421:Models, Animal; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D020303:Rats, Inbred Dahl; D015843:Serpins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D000071161:Forkhead Box Protein O1
D051858:Forkhead Transcription Factors; D006861:Hydrogen Peroxide; D048670:MAP Kinase Kinase 4; D009419:Nerve Tissue Proteins; D015843:Serpins; C051324:kallistatin; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1