positive regulation of mitotic cell cycle

Definition

Target type: biologicalprocess

Any process that activates or increases the rate or extent of progression through the mitotic cell cycle. [GOC:dph, GOC:go_curators, GOC:tb]

Positive regulation of mitotic cell cycle is a fundamental biological process that ensures the accurate and timely duplication of the genome and the formation of two daughter cells during cell division. This process is tightly regulated by a complex network of signaling pathways and protein interactions, ensuring that the cell only enters mitosis when it is properly prepared.

**Key Components:**

* **Cyclins and Cyclin-Dependent Kinases (CDKs):** These proteins act as master regulators of the cell cycle. Cyclins are regulatory proteins whose levels fluctuate throughout the cell cycle, while CDKs are catalytic kinases that phosphorylate target proteins. The complex formation of cyclins and CDKs is crucial for progression through different phases of the cell cycle.
* **Cyclin-CDK Complexes:** Different cyclin-CDK complexes are active during specific stages of the cell cycle. For instance, cyclin D-CDK4/6 complex is active during G1 phase, cyclin E-CDK2 during the G1-S transition, and cyclin B-CDK1 during the G2-M transition.
* **Checkpoint Mechanisms:** These mechanisms ensure that the cell cycle proceeds only when critical events are completed. For example, the DNA damage checkpoint prevents entry into mitosis until DNA damage is repaired.
* **Ubiquitin-Proteasome System:** This system plays a crucial role in regulating the degradation of key proteins involved in the cell cycle, including cyclins and other regulatory proteins.

**Process Summary:**

1. **G1 Phase:** During this phase, cells accumulate nutrients and grow in size. Cyclin D-CDK4/6 complexes promote the phosphorylation of retinoblastoma protein (Rb), releasing transcription factors that drive cell cycle progression.
2. **G1-S Transition:** As cyclin E-CDK2 activity increases, the cell commits to DNA replication. This complex triggers the expression of genes required for S phase entry.
3. **S Phase:** DNA replication occurs.
4. **G2 Phase:** Cells continue to grow, synthesize proteins, and prepare for mitosis.
5. **G2-M Transition:** The accumulation of cyclin B-CDK1 triggers entry into mitosis. This complex activates proteins required for mitotic spindle formation and chromosome condensation.
6. **Mitosis:** This stage involves chromosome segregation and cell division.
7. **Cytokinesis:** The cytoplasm divides, ultimately forming two daughter cells.

**Regulation and Feedback:**

* **Growth Factor Signaling:** Growth factors stimulate cell cycle progression by activating signaling pathways that increase the expression of cyclins and CDKs.
* **DNA Damage Response:** When DNA damage is detected, checkpoint mechanisms inhibit cyclin-CDK activity, pausing the cell cycle until the damage is repaired.
* **Microtubule Assembly and Stability:** The proper assembly and stability of microtubules, which form the mitotic spindle, are essential for chromosome segregation. Checkpoint mechanisms monitor this process and halt mitosis if errors occur.

**Dysregulation and Disease:**

Uncontrolled cell cycle progression can lead to various diseases, including cancer. Mutations in genes that regulate cell cycle checkpoints or that encode cyclins or CDKs can lead to uncontrolled cell growth and tumor formation.

**Conclusion:**

Positive regulation of the mitotic cell cycle is a tightly controlled process that ensures the faithful duplication of the genome and the production of healthy daughter cells. This process is essential for normal development, tissue repair, and maintaining the integrity of the organism.'
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Proteins (19)

Compounds (729)