Precocious G1/S transitions and genomic instability: the origin connection

Area of Science:

• Cell Biology
• Genetics
• Molecular Biology

Background:

• Genomic instability, a hallmark of cancer, is often linked to deregulation of the G1/S cell cycle transition.
• Mutations in genes controlling the G1/S transition are prevalent in human cancers.
• Premature entry into S phase can lead to suboptimal DNA replication and bypass cellular surveillance mechanisms.

Purpose of the Study:

• To review the mechanistic understanding of genomic instability caused by premature G1/S transition.
• To discuss the dual surveillance system in budding yeast that regulates S phase completion before mitosis.
• To elucidate how premature G1 exit compromises this surveillance system.

Main Methods:

• Review of existing literature, focusing on budding yeast data.
• Analysis of cellular surveillance mechanisms involving licensed origins and replication forks.
• Examination of the impact of precocious G1 exit on DNA replication and cell cycle control.

Main Results:

• A dual surveillance system in yeast relies on licensed origins and stalled replication forks to ensure replication completion before mitosis.
• Premature exit from G1 phase can disable this surveillance system.
• This disabling effect results from insufficient origin licensing and resource accumulation, coupled with a false metabolic readiness signal.

Conclusions:

• Deregulation of the G1/S transition and premature cell cycle entry are significant causes of genomic instability.
• The dual surveillance system is crucial for maintaining genome integrity but is vulnerable to precocious G1 exit.
• Understanding these mechanisms in yeast provides insights into cancer development and potential therapeutic targets.