Related Experiment Video
Updated: May 22, 2026
12:26
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Phosphorylation by cyclin-dependent kinase-9 controls ubiquitin-conjugating enzyme-2A function.
Andrei Shchebet1, Oleksandra Karpiuk, Elisabeth Kremmer
1Department of Molecular Oncology, Universit of Göttingen Medical Center, Göttingen, Germany.
Cell Cycle (Georgetown, Tex.)
|May 18, 2012
Summary
Cyclin-dependent kinase-9 (CDK9) activates the UBE2A enzyme, crucial for histone H2B monoubiquitination (H2Bub1) and PCNA ubiquitination, impacting DNA repair and cancer therapy.
Area of Science:
- Molecular Biology
- Epigenetics
- Cancer Research
Background:
- Cyclin-dependent kinase-9 (CDK9) regulates transcriptional elongation and histone modifications.
- CDK9's role in maintaining histone H2B monoubiquitination (H2Bub1) is partially linked to RNA polymerase II (RNAPII) C-terminal domain (CTD) phosphorylation.
- Previous studies indicated CDK9's influence on H2Bub1 might involve other targets beyond RNAPII CTD.
Purpose of the Study:
- To investigate if CDK9 directly targets and activates the ubiquitin-conjugating enzyme for H2B monoubiquitination.
- To explore the role of CDK9 in the activity of the ubiquitin-conjugating enzyme UBE2A.
- To determine if CDK9's function extends to other ubiquitination events, such as PCNA monoubiquitination.
Main Methods:
- Investigated the interaction between CDK9 and UBE2A using biochemical assays.
- Performed in vitro phosphorylation assays to assess CDK9's effect on UBE2A.
- Analyzed the impact of CDK9 knockdown on H2Bub1 and PCNA monoubiquitination levels.
Main Results:
- Demonstrated specific interaction between UBE2A and CDK9, with CDK9 phosphorylating and activating UBE2A in vitro.
- CDK9 knockdown reduced UBE2A phosphorylation, H2Bub1 levels, and impaired UBE2A-dependent PCNA monoubiquitination.
- Identified CDK9 as essential for UBE2A activity in human cells.
Conclusions:
- CDK9 is required for human UBE2A activity, influencing both H2Bub1 and PCNA monoubiquitination.
- These findings establish a novel role for CDK9 in regulating key ubiquitination events involved in DNA repair.
- CDK9 presents a potential combinatorial therapeutic target for enhancing cancer treatments that induce DNA damage.
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