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Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
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P53 regulates CCAAT/Enhancer binding protein β gene expression.
Biao Hu1, Tianju Liu2, Zhe Wu2
1Department of Internal Medicine, University of Michigan Medical School, 1600 Huron Parkway, Ann Arbor, MI 48109 USA.
Gene
|August 4, 2023
Summary
The tumor suppressor P53 represses CCAAT/enhancer-binding protein β (C/EBPβ) gene expression. P53 controls both C/EBPβ transcription and translation, affecting its LAP and LIP isoforms differently.
Area of Science:
- Molecular Biology
- Cancer Biology
- Gene Regulation
Background:
- CCAAT/enhancer-binding protein β (C/EBPβ) is a transcription factor involved in various cellular processes and diseases.
- C/EBPβ exists in two isoforms, LAP and LIP, translated from the same mRNA, with LIP inhibiting LAP activity.
- The regulation of C/EBPβ gene expression and the LAP:LIP ratio remains unclear.
Purpose of the Study:
- To investigate the role of P53 in regulating C/EBPβ gene expression.
- To elucidate the mechanism by which P53 affects C/EBPβ transcription and translation.
- To determine if P53 differentially regulates C/EBPβ LAP and LIP isoforms.
Main Methods:
- Promoter analysis to identify P53 response elements (P53RE) in the C/EBPβ gene.
- Electrophoretic Mobility Shift Assay (EMSA) and chromatin immunoprecipitation to confirm P53 binding.
- Gene transfection studies with P53 overexpression and dominant-negative P53.
- Western blot analysis to assess C/EBPβ isoform expression.
- 5' untranslated region (5'UTR) constructs to study translational control.
Main Results:
- A conserved P53RE was identified in the C/EBPβ promoter, with P53 binding confirmed by EMSA and ChIP.
- P53 overexpression suppressed C/EBPβ transcription and expression, while dominant-negative P53 enhanced it.
- P53 differentially regulated the translation of LAP and LIP isoforms via eIF4E and eIF4E-BP1.
- The 5'UTR of C/EBPβ plays a crucial role in the differential translation of LAP and LIP isoforms.
Conclusions:
- P53 acts as a repressor of C/EBPβ gene expression at both transcriptional and translational levels.
- P53 exhibits differential regulation of C/EBPβ LAP and LIP isoforms.
- This study reveals a novel mechanism for P53 antagonizing C/EBPβ activity.
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