G2/M checkpoint

Definition

The G2/M checkpoint is a critical regulatory point in the cell cycle that ensures cells are fully prepared to enter mitosis. This checkpoint assesses DNA integrity and repairs any damage before the cell divides, preventing the propagation of mutations and ensuring proper cell function.

5 Must Know Facts For Your Next Test

1. The G2/M checkpoint is primarily controlled by the protein complex cyclin B-CDK1, which is crucial for initiating mitosis.
2. Cells with damaged DNA will not pass the G2/M checkpoint; instead, they are either repaired or directed towards apoptosis if the damage is irreparable.
3. Radiation therapy exploits the G2/M checkpoint by targeting cells during this phase when they are more susceptible to damage and less capable of repairing themselves.
4. The integrity of the G2/M checkpoint is vital for maintaining genomic stability and preventing tumorigenesis in normal cells.
5. Cancer cells often have dysfunctional G2/M checkpoints, allowing them to proliferate despite having DNA damage, making them more resistant to certain treatments.

Review Questions

• How does the G2/M checkpoint contribute to cellular integrity during the cell cycle?
  • The G2/M checkpoint plays a crucial role in maintaining cellular integrity by ensuring that any DNA damage is repaired before a cell enters mitosis. If there are any issues detected during this checkpoint, the cell can halt its progression into mitosis, allowing time for repair mechanisms to fix the damage. This process is essential in preventing the division of potentially harmful mutations, which could lead to cancerous growths.
• Discuss the implications of targeting the G2/M checkpoint in radiation therapy for cancer treatment.
  • Targeting the G2/M checkpoint in radiation therapy takes advantage of the fact that cancer cells often have an impaired ability to repair DNA damage. By applying radiation when cells are at this checkpoint, treatments can enhance the likelihood of causing irreparable damage, leading to cell death. Understanding how to manipulate this checkpoint can increase the effectiveness of therapies by selectively killing cancer cells while sparing healthy ones.
• Evaluate the potential consequences of a dysfunctional G2/M checkpoint in cancer biology and treatment resistance.
  • A dysfunctional G2/M checkpoint allows cancer cells to bypass critical repair mechanisms, enabling them to continue dividing even when they possess significant DNA damage. This unchecked proliferation contributes to tumorigenesis and can lead to treatment resistance as these cells adapt to survive therapies designed to target dividing cells. Evaluating this dysfunction provides insights into personalized treatment strategies that might include enhancing checkpoint control or combining therapies that target both cancer cell survival pathways and their ability to repair DNA damage.

Related terms

Cell Cycle: The series of phases that a cell goes through as it grows and divides, including G1, S, G2, and M phases.

DNA Repair Mechanisms: Biological processes that identify and correct damage to the DNA molecules that encode the genome.

Apoptosis: The process of programmed cell death that occurs in multicellular organisms, often activated in response to severe DNA damage or cellular stress.