Cocaine-induced DNA-PK relieves RNAP II pausing by promoting TRIM28 phosphorylation.

Area of Science:

• Molecular Biology
• Virology
• Pharmacology

Background:

• Drug abuse, particularly cocaine use, is a significant barrier to effective HIV control.
• Understanding the molecular mechanisms by which cocaine affects HIV replication is crucial for developing targeted interventions.

Purpose of the Study:

• To elucidate the molecular pathways through which cocaine enhances HIV transcription and replication.
• To identify key protein interactions and modifications involved in cocaine-induced HIV gene expression.

Main Methods:

• Investigated the effect of cocaine on DNA-dependent protein kinase (DNA-PK) expression and activation.
• Analyzed DNA-PK recruitment to the HIV long terminal repeat (LTR) using cellular assays.
• Examined the phosphorylation status of RNA polymerase II (RNAP II) CTD and TRIM28.
• Assessed the activity of cyclin-dependent kinases (CDKs) and transcriptional elongation factors.

Main Results:

• Cocaine upregulates and activates DNA-PK, promoting its nuclear translocation and recruitment to the HIV LTR.
• Cocaine-induced DNA-PK enhances HIV transcription by promoting RNAP II CTD phosphorylation at Ser5 and Ser2.
• Cocaine activates CDK7, leading to CDK9 phosphorylation and enhanced P-TEFb activity.
• Cocaine specifically phosphorylates TRIM28 at Serine 824, converting it from a repressor to an activator of HIV transcription.

Conclusions:

• Cocaine significantly enhances HIV transcription and replication through the activation of DNA-PK and subsequent modifications of key transcriptional regulators.
• The findings reveal novel molecular targets for therapeutic strategies aimed at mitigating cocaine's adverse effects on HIV-infected individuals.