Transcriptional regulation of UCP4 by NF-kappaB and its role in mediating protection against MPP+ toxicity.
Mitochondrial uncoupling protein-4 (UCP4) enhances neuronal cell survival in MPP(+)-induced toxicity by suppressing oxidative stress and preserving intracellular ATP and mitochondrial membrane potential. UCP4 expression is increased by MPP(+), but its regulation is unknown. Using serial human UCP4 promoter-luciferase reporter gene constructs, we identified and characterized several cis-acting elements that can regulate UCP4 expression. Core promoter activity exists within 100 bp upstream of the transcription initiation site (TIS=+1). Both CAAT box (-33/-27) and Sp1 (-62/-49) elements are crucial and act synergistically in its transcription. We identified a NF-kappaB putative binding site at -507/-495. Mutation of this site significantly decreased UCP4 promoter activity. Activation of NF-kappaB by TNFalpha or cycloheximide increased, whereas its inhibition by 4-hydroxy-2-nonenal or transfection of pIkappaBalphaM suppressed, UCP4 promoter activity. NF-kappaB inhibition significantly suppressed the MPP(+)-induced increase in UCP4 expression. MPP(+) increased specific binding of NF-kappaB protein complexes to this site in electrophoretic mobility shift assay. Both UCP4 knockdown and NF-kappaB inhibition exacerbated MPP(+)-induced cell death. We present the first direct evidence that UCP4 is regulated by NF-kappaB, mediated via a functional NF-kappaB site in its promoter region, and that UCP4 has a significant role in NF-kappaB prosurvival signaling, mediating its protection against MPP(+) toxicity.
Ho
Jessica Wing-Man
JW
Division of Neurology, University Department of Medicine, University of Hong Kong, Hong Kong, People's Republic of China.
Ho
Philip Wing-Lok
PW
Zhang
Wei-Yi
WY
Liu
Hui-Fang
HF
Kwok
Ken Hon-Hung
KH
Yiu
David Chi-Wai
DC
Chan
Koon-Ho
KH
Kung
Michelle Hiu-Wai
MH
Ramsden
David Boyer
DB
Ho
Shu-Leong
SL
D015655:1-Methyl-4-phenylpyridinium / Q000633:toxicity*; D000447:Aldehydes / Q000494:pharmacology; D001665:Binding Sites / Q000235:genetics; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000071245:Mitochondrial Uncoupling Proteins; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051839:NFI Transcription Factors / Q000235:genetics / Q000378:metabolism; D018696:Neuroprotective Agents / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics
D000447:Aldehydes; D026901:Membrane Transport Proteins; D000071245:Mitochondrial Uncoupling Proteins; D016328:NF-kappa B; D051839:NFI Transcription Factors; D018696:Neuroprotective Agents; D034741:RNA, Small Interfering; C117577:SLC25A27 protein, human; D016329:Sp1 Transcription Factor; C027576:4-hydroxy-2-nonenal; D015655:1-Methyl-4-phenylpyridinium