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The G 2-M checkpoint occurs between the G 2 and M phases. The spindle checkpoint occurs during the M phase. Key cyclins associated with each phase are shown. Cell cycle checkpoints are control mechanisms in the eukaryotic cell cycle which ensure its proper progression.
Cells with a defective G 2-M checkpoint will undergo apoptosis or death after cell division if they enter the M phase before repairing their DNA. [1] The defining biochemical feature of this checkpoint is the activation of M-phase cyclin-CDK complexes, which phosphorylate proteins that promote spindle assembly and bring the cell to metaphase. [2]
The spindle checkpoint, also known as the metaphase-to-anaphase transition, the spindle assembly checkpoint (SAC), the metaphase checkpoint, or the mitotic checkpoint, is a cell cycle checkpoint during metaphase of mitosis or meiosis that prevents the separation of the duplicated chromosomes until each chromosome is properly attached to the ...
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
The G1/S checkpoint, G2/M checkpoint, and the checkpoint between metaphase and anaphase all monitor for DNA damage and halt cell division by inhibiting different cyclin-CDK complexes. The p53 tumor-suppressor protein plays a crucial role at the G1/S checkpoint and the G2/M checkpoint. Activated p53 proteins result in the expression of many ...
DNA damage checkpoint is a signal transduction pathway that blocks cell cycle progression in G1, G2 and metaphase and slows down the rate of S phase progression when DNA is damaged. It leads to a pause in cell cycle allowing the cell time to repair the damage before continuing to divide.
Cell cycle checkpoint, control mechanisms in eukaryotic cell division G1 restriction point; S postreplication checkpoint, prevents cell cycle progression until postreplication repair; G2-M DNA damage checkpoint; M spindle checkpoint, prevents anaphase onset until all chromosomes are properly attached to the spindle; Immune checkpoint
Role in cancer: Cyclin-dependent kinase inhibitor (CKI) mutants are frequent in human cancers. The function of CKI is to stop cell growth when there are mistakes due to DNA damage. Once a cell is stopped at a checkpoint due to DNA damage, either the damage is repaired or the cell is induced to perform apoptosis. [9]