Nemo-like kinase suppresses a wide range of transcription factors, including nuclear factor-kappaB.
Nemo-like kinase (NLK) is a serine/threonine kinase that suppresses the transcription activity of the beta-catenin-T-cell factor (TCF) complex through phosphorylation of TCF. Our previous study showed that NLK overexpression induces apoptosis in DLD-1 human colon cancer cells and that apoptosis induction presumably requires a mechanism other than the suppression of beta-catenin-TCF complex. Luciferase reporter gene assay with pNF-kappaB-Luc revealed that NLK could suppress transcription activity of NF-kappaB in a kinase-dependent manner. However, it appeared that transcription co-activators of NF-kappaB, such as CREB binding protein (CBP)/p300, were likely to be the direct targets of NLK, rather than NF-kappaB itself. Luciferase reporter gene analysis of GAL4-CBP fusion proteins revealed that the C-terminal region of CBP was critical for transcription suppression by NLK. In vitro kinase assay showed that NLK could phosphorylate the C-terminal domain of CBP. However, HAT activity was not suppressed by the induction of wild-type NLK in DLD-1 cells. Furthermore, we observed that NLK suppressed the transcription activity of AP-1, Smad, and p53, all of which also utilize CBP as a co-activator. The extent of suppression by NLK was similar among the transcription factors tested (50-60% reduction). Our results suggest that NLK may suppress a wide range of gene expression, possibly through CBP.
Yasuda
Jun
J
Cancer Transcriptome Project, National Cancer Center Research Institute, Chuo-ku, Tokyo 104-0045, Japan. jyasuda@ncc.go.jp
Yokoo
Hideki
H
Yamada
Tesshi
T
Kitabayashi
Issay
I
Sekiya
Takao
T
Ichikawa
Hitoshi
H
D050882:CREB-Binding Protein; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000502:physiology*; D017930:Genes, Reporter; D006801:Humans; D051550:I-kappa B Kinase; D015151:Immunoblotting; D016328:NF-kappa B / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection
D016328:NF-kappa B; D009687:Nuclear Proteins; D015534:Trans-Activators; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human