The cell-cycle transcriptional network generates and transmits a pulse of transcription once each cell cycle

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Cyclin-dependent kinases (CDKs) and transcription factor (TF) networks are crucial for cell-cycle gene regulation.
• The exact interplay between CDKs and TF networks in the cell-cycle transcriptional program is not fully understood.

Purpose of the Study:

• To elucidate the precise mechanisms by which CDK and TF networks coordinate cell-cycle gene regulation.
• To investigate the role of early G1 inhibitors in preventing premature transcriptional events.

Main Methods:

• Investigated the ability of the TF network to generate transcriptional pulses independently of CDK oscillations.
• Examined the inhibitory roles of early G1 repressors, including transcriptional corepressors and APC^Cdh1.
• Assessed how G1 cyclin-CDKs modulate TF protein activity and accumulation by inhibiting G1 transcriptional corepressors (Whi5, Stb1) and APC^Cdh1.

Main Results:

• The TF network can generate a transcriptional pulse independent of CDK oscillations.
• Early G1 inhibitors (transcriptional corepressors, APC^Cdh1) prevent premature pulse firing.
• G1 cyclin-CDKs promote TF protein activation and accumulation, initiating the transcriptional pulse.

Conclusions:

• A novel oscillatory mechanism for cell-cycle transcription involves a pulse-generating TF network.
• Global, phase-specific transcription is achieved through a network that fires once per cell cycle.
• This mechanism highlights the coordinated roles of CDKs and TFs in precise cell-cycle progression.