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Quantitative Proteomics of the CDK9 Interactome Reveals a Function of the HSP90-CDC37-P-TEFb Complex for BETi-Induced
Cong Wang1,2, Chunjing Chen1, Zhenrui Pan1
1State Key Laboratory of Cellular Stress Biology and Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, Fujian 361102, China.
Abstract:
Brd4 has been intensively investigated as a promising drug target because of its implicated functions in oncogenesis, inflammation, and HIV-1 transcription. The formation of the Brd4-P-TEFb (CDK9/Cyclin T1) complex and its regulation of transcriptional elongation are critical for HIV latency reactivation and expression of many oncogenes. To further investigate the mechanism of the Brd4-P-TEFb complex in controlling elongation, mass spectrometry-based quantitative proteomics of the CDK9 interactome was performed. Upon treatment with the selective BET bromodomain inhibitor JQ1, 352 proteins were successfully identified with high confidence as CDK9-interacting proteins. Among them, increased bindings of HSP90 and CDC37 to CDK9 were particularly striking, and our data suggest that the HSP90-CDC37-P-TEFb complex is involved in controlling the dynamic equilibrium of the P-TEFb complex during BETi-induced reactivation of HIV-1 latency. Furthermore, the HSP90-CDC37-P-TEFb complex directly regulates HIV-1 transcription and relies on recruitment by heat shock factor 1 (HSF1) for binding to the HIV-1 promoter. These results advance the understanding of HSP90-CDC37-P-TEFb in HIV-1 latency reversal and enlighten the development of potential strategies to eradicate HIV-1 using a combination of targeted drugs.
Insights
Bromodomain 4 (Brd4) inhibitors reveal a novel HSP90-CDC37-P-TEFb complex crucial for HIV-1 transcription and latency reactivation. This finding offers new strategies for HIV-1 eradication.
Area of Science:
- Molecular Biology
- Virology
- Drug Discovery
Background:
- Bromodomain 4 (Brd4) is a key target in oncogenesis, inflammation, and HIV-1 transcription.
- The Brd4-P-TEFb (CDK9/Cyclin T1) complex regulates transcriptional elongation, critical for HIV latency and oncogene expression.
Purpose of the Study:
- To investigate the mechanism of the Brd4-P-TEFb complex in controlling transcriptional elongation.
- To identify novel CDK9-interacting proteins and their roles in HIV-1 latency.
Main Methods:
- Mass spectrometry-based quantitative proteomics to analyze the CDK9 interactome.
- Treatment with the BET bromodomain inhibitor JQ1.
Main Results:
- Identified 352 high-confidence CDK9-interacting proteins upon JQ1 treatment.
- Observed increased binding of HSP90 and CDC37 to CDK9, forming an HSP90-CDC37-P-TEFb complex.
- Demonstrated that this complex regulates HIV-1 transcription and is recruited by heat shock factor 1 (HSF1) to the HIV-1 promoter.
Conclusions:
- The HSP90-CDC37-P-TEFb complex controls P-TEFb dynamic equilibrium during BET inhibitor-induced HIV-1 latency reactivation.
- This complex directly regulates HIV-1 transcription, providing insights for HIV-1 eradication strategies.
