apoptotic nuclear changes

Definition

Target type: biologicalprocess

Alterations undergone by nuclei at the molecular and morphological level as part of the execution phase of apoptosis. [GOC:mah, GOC:mtg_apoptosis]

Apoptotic nuclear changes are a hallmark of programmed cell death, a tightly regulated process that eliminates unwanted or damaged cells. These changes involve a series of events that ultimately lead to the dismantling of the nucleus, resulting in the fragmentation of the cell's DNA and the eventual breakdown of the entire cell.

**1. Nuclear Envelope Disassembly:** The nuclear envelope, a double membrane that surrounds the nucleus, begins to break down. This is facilitated by the activation of nuclear lamins, proteins that provide structural support to the nuclear envelope. These lamins become phosphorylated, causing them to detach from the nuclear membrane and disassemble.

**2. Chromatin Condensation:** The chromatin, the complex of DNA and proteins within the nucleus, undergoes significant changes. The DNA condenses, becoming more tightly packed and appearing as dense clumps under a microscope. This condensation is driven by specific enzymes that modify the histones, proteins around which DNA is wrapped.

**3. DNA Fragmentation:** The condensed DNA is cleaved into fragments of specific sizes by a specialized enzyme called caspase-activated DNase (CAD). This fragmentation is a key feature of apoptosis and is used to identify cells undergoing this process.

**4. Nuclear Fragmentation:** As the DNA fragments, the nucleus itself begins to fragment. The condensed chromatin and the fragmented DNA are packaged into separate structures called apoptotic bodies. These bodies are surrounded by a membrane and are released from the cell.

**5. Nuclear Lysis:** In the final stages of apoptosis, the apoptotic bodies can be further degraded and released into the surrounding environment. This process is known as nuclear lysis.

**6. Apoptosis Execution:** The apoptotic nuclear changes are tightly controlled by a complex network of signaling pathways involving caspase enzymes. These pathways are activated by various stimuli, including DNA damage, growth factor withdrawal, and cytotoxic agents.

**7. Significance:** These changes ensure the efficient dismantling of the cell's genetic material, preventing the release of potentially harmful cellular contents into the surrounding environment, thereby minimizing the risk of inflammation or immune responses.

**Overall, apoptotic nuclear changes are a vital part of the programmed cell death process, ensuring the orderly elimination of cells while minimizing damage to the surrounding tissues.'
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Proteins (1)

Compounds (1)