CDK9 inhibitors define elongation checkpoints at both ends of RNA polymerase II-transcribed genes

Area of Science:

• Molecular Biology
• Gene Regulation
• Biochemistry

Background:

• Transcription elongation is regulated by checkpoints.
• Cyclin-dependent kinase (CDK) 9 phosphorylates negative transcription elongation factors (NTEFs) to facilitate passage through early-elongation checkpoints.

Purpose of the Study:

• To map CDK9 inhibitor-sensitive checkpoints genome-wide in human cells.
• To investigate the role of early-elongation checkpoints in RNA polymerase (pol) II transcription.
• To identify novel checkpoints in gene expression regulation.

Main Methods:

• Global run-on sequencing (GRO-seq) was employed.
• CDK9 inhibitors were used to probe checkpoint sensitivity.
• Analysis of RNA polymerase II C-terminal domain modifications.

Main Results:

• Early-elongation checkpoints are a general feature of human genes transcribed by pol II.
• These checkpoints operate independently of polymerase stalling.
• A novel polyadenylation (poly(A))-associated elongation checkpoint was identified.
• Premature transcription termination near poly(A) sites was observed.
• Pol II termination at this new checkpoint shows modification patterns similar to normal downstream poly(A) site processing.

Conclusions:

• Early-elongation checkpoints are widespread and crucial for RNA polymerase II transcription.
• The newly discovered poly(A)-associated elongation checkpoint significantly impacts gene expression regulation.
• Shared mechanisms may govern transcription termination at different sites.