G2/M Checkpoint

Definition

The G2/M checkpoint is a crucial regulatory point in the cell cycle that occurs before a cell enters mitosis. It ensures that all DNA has been accurately replicated and that there are no DNA damages or errors before the cell divides. This checkpoint plays a significant role in maintaining genomic stability and preventing the propagation of damaged DNA to daughter cells.

5 Must Know Facts For Your Next Test

1. The G2/M checkpoint is activated if there is any DNA damage detected during the G2 phase, prompting the cell to halt progression into mitosis.
2. Proteins such as p53 play a critical role in the G2/M checkpoint by monitoring DNA integrity and mediating repair processes.
3. If the damage is irreparable, the G2/M checkpoint can trigger programmed cell death (apoptosis) to prevent harmful mutations from passing on to daughter cells.
4. In cancer cells, mutations in checkpoint proteins can lead to unchecked cell division and contribute to tumor development.
5. Research into G2/M checkpoint mechanisms provides insight into potential cancer therapies that aim to restore normal cell cycle control.

Review Questions

• How does the G2/M checkpoint contribute to cellular health and genomic stability?
  • The G2/M checkpoint contributes to cellular health by ensuring that DNA has been fully replicated without errors before cell division occurs. It acts as a quality control mechanism, preventing cells with damaged DNA from proceeding into mitosis. This checkpoint helps maintain genomic stability by allowing time for repair processes to fix any detected issues, thereby reducing the risk of passing on mutations to daughter cells.
• Discuss the role of key proteins such as p53 in regulating the G2/M checkpoint and their implications for cancer biology.
  • Key proteins like p53 play a pivotal role in regulating the G2/M checkpoint by monitoring DNA integrity and facilitating repair pathways. When DNA damage is detected, p53 can halt cell cycle progression at this checkpoint, allowing for necessary repairs or triggering apoptosis if damage is irreparable. Mutations in p53 are commonly found in various cancers, which allows cells to bypass this critical checkpoint and continue dividing despite having damaged DNA, contributing to tumor growth.
• Evaluate how dysregulation of the G2/M checkpoint can impact cancer therapy strategies and patient outcomes.
  • Dysregulation of the G2/M checkpoint can significantly impact cancer therapy strategies because many treatments rely on inducing DNA damage in cancer cells. If cancer cells have mutations that allow them to bypass this checkpoint, they may survive and proliferate despite treatment. This escape can lead to poor patient outcomes as tumors may become more aggressive or resistant to therapies. Understanding the mechanisms behind G2/M checkpoint dysregulation can inform strategies to enhance therapeutic efficacy by targeting these pathways in cancer cells.

Related terms

Cell Cycle: The series of stages that a cell goes through to divide and replicate, including G1, S, G2, and M phases.

DNA Repair Mechanisms: Biological processes that detect and correct damage to the DNA molecules that encode the genome, helping maintain genetic integrity.

Cyclins and Cyclin-Dependent Kinases (CDKs): Regulatory proteins involved in the control of the cell cycle, where cyclins activate CDKs to facilitate progression through different phases.