Abstract
Gankyrin is an oncoprotein commonly overexpressed in hepatocellular carcinomas. It interacts with multiple proteins and accelerates degradation of tumor suppressors Rb and p53. Since gankyrin consists of 7 ankyrin repeats and is structurally similar to IkappaBs, we investigated its interaction with NF-kappaB. We found that gankyrin directly binds to RelA. In HeLa and 293 cells, overexpression of gankyrin suppressed the basal as well as TNFalpha-induced transcriptional activity of NF-kappaB, whereas down-regulation of gankyrin increased it. Gankyrin did not affect the NF-kappaB DNA-binding activity or nuclear translocation of RelA induced by TNFalpha in these cells. Leptomycin B that inhibits nuclear export of RelA suppressed the NF-kappaB activity, which was further suppressed by gankyrin. The inhibitory effect of gankyrin was abrogated by nicotinamide as well as down-regulation of SIRT1, a class III histone deacetylase. Thus, gankyrin binds to NF-kappaB and suppresses its activity at the transcription level by modulating acetylation via SIRT1.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Binding Sites / genetics
-
Blotting, Western
-
Cell Line
-
Cell Line, Tumor
-
Electrophoretic Mobility Shift Assay
-
Fatty Acids, Unsaturated / pharmacology
-
Green Fluorescent Proteins / genetics
-
Green Fluorescent Proteins / metabolism
-
HeLa Cells
-
Humans
-
Immunoprecipitation
-
Interferon-alpha / pharmacology
-
Luciferases / genetics
-
Luciferases / metabolism
-
Microscopy, Fluorescence
-
NF-kappa B / genetics
-
NF-kappa B / metabolism*
-
Niacinamide / pharmacology
-
Proteasome Endopeptidase Complex / genetics
-
Proteasome Endopeptidase Complex / metabolism*
-
Protein Binding / genetics
-
Proto-Oncogene Proteins / genetics
-
Proto-Oncogene Proteins / metabolism*
-
RNA, Small Interfering / genetics
-
Recombinant Fusion Proteins / genetics
-
Recombinant Fusion Proteins / metabolism
-
Sirtuin 1
-
Sirtuins / genetics
-
Sirtuins / metabolism
-
Transcription Factor RelA / genetics
-
Transcription Factor RelA / metabolism*
-
Transcription, Genetic / drug effects
-
Transfection
Substances
-
Fatty Acids, Unsaturated
-
Interferon-alpha
-
NF-kappa B
-
PSMD10 protein, human
-
Proto-Oncogene Proteins
-
RELA protein, human
-
RNA, Small Interfering
-
Recombinant Fusion Proteins
-
Transcription Factor RelA
-
Green Fluorescent Proteins
-
Niacinamide
-
Luciferases
-
Proteasome Endopeptidase Complex
-
SIRT1 protein, human
-
Sirtuin 1
-
Sirtuins
-
leptomycin B