| Summary: | 碩士 === 國立臺灣大學 === 生化科學研究所 === 92 === The small nuclear RING finger protein 4 (RNF4) contain C3HC4-type RING motif in the c-terminal region. RNF4 modulates both steroid-receptor-dependent and basal transcription and interacts with a variety of nuclear proteins. RNF4 can also act as a transcriptional co-repressor or co-activator. In this study, we demonstrated that RNF4 enhance AP-1 (activating protein-1) transcriptional activity. Using luciferase assay, we showed that RNF4 regulates AP-1 through c-Jun amino-terminal kinase (JNK) and extracellular signal-regulated kinases (ERK) pathway. In addition, GST-pull down assay indicated that RNF4 can interact with p-JNK and p-ERK. When RING finger motif is deleted, RNF4 loses its ability to enhance AP-1 activity. T127, S166 phosphorylation sites of RNF4 is critical to activate AP-1 transcription. If the two phosphorylation sites mutated to Alanine, RNF4 lose the enhancement of AP-1 activity. Based on these results, we propose that RNF4 enhance AP-1 transcription activity.
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