establishment of mitotic spindle orientation

Definition

Target type: biologicalprocess

A cell cycle process that sets the alignment of mitotic spindle relative to other cellular structures. [GOC:ems]

The establishment of mitotic spindle orientation is a complex process that ensures accurate chromosome segregation during cell division. It involves a series of steps that integrate cues from the cell's internal environment and external signals. Here is a detailed description:

1. **Microtubule Nucleation and Organization:**
- Microtubules, the structural components of the spindle, are nucleated from centrosomes, which are microtubule organizing centers.
- During prophase, centrosomes duplicate and migrate to opposite poles of the cell, forming the spindle poles.
- Microtubules emanate from these poles, forming a bipolar spindle apparatus.

2. **Spindle Pole Positioning and Migration:**
- Initial spindle pole positioning is often influenced by inherited asymmetry from the previous cell cycle.
- The spindle poles are guided towards specific locations within the cell by various factors:
- **Cortical cues:** The cell cortex (the outermost layer of the cytoplasm) can provide cues for spindle orientation.
- **Astral microtubules:** Microtubules that radiate from the spindle poles towards the cell cortex can interact with cortical proteins, influencing spindle positioning.
- **Molecular motors:** Proteins like dynein and kinesin can move along microtubules and contribute to spindle pole movement.

3. **Chromosome Capture and Alignment:**
- Microtubules emanating from the spindle poles capture chromosomes via kinetochores, specialized protein structures on the centromere of each chromosome.
- As microtubules attach to kinetochores, they pull chromosomes towards the spindle poles, aligning them at the metaphase plate.

4. **Spindle Orientation and Maintenance:**
- Once chromosomes are aligned, the spindle axis is established, and its orientation is crucial for proper cell division.
- Spindle orientation is influenced by various factors:
- **Cell polarity:** Intrinsic cell polarity can dictate spindle orientation, ensuring daughter cells inherit specific cellular components.
- **External cues:** Environmental signals, such as cell-cell contact or gradients of signaling molecules, can influence spindle orientation.
- **Force generation:** Microtubule dynamics and motor proteins generate forces that contribute to spindle orientation and stability.

5. **Spindle Elongation and Separation:**
- During anaphase, sister chromatids separate and move towards opposite poles of the cell, driven by the shortening of microtubules.
- The spindle elongates, pushing the poles further apart.

6. **Cytokinesis:**
- After chromosome segregation, cytokinesis (division of the cytoplasm) occurs, completing cell division.
- Spindle orientation directly influences the cleavage plane, ensuring the formation of two daughter cells with distinct identities.

The accurate establishment of mitotic spindle orientation is essential for the faithful partitioning of genetic material and cellular components, ensuring proper cell division and development.'
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Proteins (6)

Compounds (337)