positive regulation of cytokinesis

Definition

Target type: biologicalprocess

Any process that activates or increases the frequency, rate or extent of the division of the cytoplasm of a cell, and its separation into two daughter cells. [GOC:mah]

Positive regulation of cytokinesis is a fundamental cellular process that ensures the proper division of the cytoplasm and organelles during cell division, ultimately leading to the formation of two daughter cells. It involves a tightly orchestrated series of events that are regulated by a complex network of signaling pathways and proteins.

Here's a detailed description:

**1. Initiation:**
- After nuclear division (mitosis or meiosis), the contractile ring, primarily composed of actin filaments and myosin II, assembles at the cell equator.
- This ring formation is regulated by various factors, including Rho GTPases (particularly RhoA) and their downstream effectors, like ROCK (Rho-associated protein kinase).
- Localization of these components is crucial for the ring's formation and proper positioning.

**2. Contraction:**
- The contractile ring starts to contract, driven by the coordinated action of myosin II motors that slide along the actin filaments.
- This process requires ATP hydrolysis and is facilitated by regulatory proteins like LIM kinases, which phosphorylate and activate cofilin, a protein that severs and depolymerizes actin filaments, allowing for efficient contraction.
- During contraction, the plasma membrane invaginates, forming a cleavage furrow that progressively deepens.

**3. Completion and Abscission:**
- The contractile ring continues to constrict, ultimately separating the two daughter cells.
- The final stage, known as abscission, involves the severing of the intercellular bridge connecting the daughter cells.
- This is achieved through the coordinated action of various proteins, including ESCRT (Endosomal Sorting Complexes Required for Transport) proteins, which mediate the formation of a membrane-bound vesicle at the bridge, leading to its eventual closure.

**4. Regulatory Factors:**
- Cytokinesis is tightly regulated by signaling pathways that respond to various cues, including cell cycle checkpoints, cell size, and external signals.
- Key signaling molecules include:
- **Cyclin-dependent kinases (CDKs):** Regulate the progression of the cell cycle and ensure cytokinesis occurs after nuclear division.
- **Aurora kinases:** Play essential roles in spindle pole formation, chromosome segregation, and proper positioning of the contractile ring.
- **Phosphoinositide 3-kinase (PI3K) and its downstream signaling pathways:** Influence the localization and activation of key cytokinesis proteins.
- **Small GTPases:** Such as RhoA, Rac1, and Cdc42, control actin dynamics and regulate the formation and contraction of the contractile ring.

**5. Importance of Positive Regulation:**
- Proper regulation of cytokinesis is crucial for cell division and organismal development.
- Errors in cytokinesis can lead to aneuploidy (abnormal chromosome number) and cellular defects, contributing to various diseases, including cancer.
- Precise control over the timing, location, and efficiency of contractile ring formation and contraction is essential for generating two viable daughter cells with an appropriate complement of organelles and genetic material.

Overall, positive regulation of cytokinesis is a complex and tightly controlled process that relies on the coordinated action of numerous proteins and signaling pathways. It ensures the accurate partitioning of cellular components, guaranteeing the successful completion of cell division and the generation of healthy daughter cells.'
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Proteins (17)

Compounds (810)