apoptotic process in bone marrow cell

Definition

Target type: biologicalprocess

The apoptotic process in cells in the bone marrow. [GOC:mah, GOC:mtg_apoptosis, PMID:17063141]

Apoptosis, or programmed cell death, is a highly regulated process in bone marrow cells that plays a crucial role in maintaining cellular homeostasis and preventing the development of diseases like cancer. It involves a series of biochemical events that ultimately lead to the dismantling of the cell.

In bone marrow, apoptosis is essential for the elimination of:

* **Damaged or dysfunctional cells:** During hematopoiesis, the process of blood cell production, some cells may undergo mutations or experience stress that makes them non-functional. Apoptosis removes these cells to prevent their accumulation and potential harm.
* **Excess cells:** Bone marrow constantly produces new blood cells, and apoptosis helps regulate the number of cells present by eliminating surplus cells.
* **Cells with developmental defects:** Some cells may develop incorrectly during hematopoiesis, and apoptosis eliminates these cells to ensure the production of functional blood cells.

The apoptotic process in bone marrow cells can be triggered by various stimuli, including:

* **Intrinsic pathways:** These pathways are activated by internal stress signals within the cell, such as DNA damage, oxidative stress, or depletion of growth factors.
* **Extrinsic pathways:** These pathways are triggered by external signals, such as death ligands like TNF-alpha or Fas ligand, which bind to receptors on the cell surface.

The apoptotic process can be broadly divided into three main phases:

**1. Initiation phase:** This phase involves the activation of caspases, a family of proteases, which act as the executioners of apoptosis.

**2. Execution phase:** Active caspases dismantle the cell by cleaving specific proteins involved in cell structure and function, including:
* **Cytoskeletal proteins:** This causes the cell to shrink and condense.
* **Nuclear lamins:** This leads to DNA fragmentation and nuclear breakdown.
* **DNA repair proteins:** This prevents the repair of DNA damage and promotes further DNA degradation.
* **Inhibitors of apoptosis proteins:** This prevents the activation of anti-apoptotic signals.

**3. Final phase:** The apoptotic cell undergoes blebbing, forming membrane-bound vesicles containing cellular debris. These vesicles are then phagocytosed by macrophages or other cells, preventing the release of harmful intracellular contents that can trigger an inflammatory response.

Dysregulation of apoptosis in bone marrow can lead to serious consequences, including:

* **Hematologic malignancies:** Insufficient apoptosis allows the accumulation of mutated or cancerous cells, leading to leukemia, lymphoma, or myeloma.
* **Immunodeficiency:** Excessive apoptosis of immune cells can compromise the immune system and increase susceptibility to infections.
* **Bone marrow failure:** Impaired apoptosis can result in the depletion of normal blood cells, causing anemia, thrombocytopenia, or neutropenia.

Understanding the intricate process of apoptosis in bone marrow cells is crucial for the development of therapeutic strategies for various hematologic disorders and for the design of novel anticancer drugs that target apoptotic pathways.'
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