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[Apoptosis or programmed cell death: regulatory and pathophysiological mechanisms]
Abstract:
Apoptosis is an active death process genetically encoded to eliminate abnormal or unwanted cells. The phenomenon is induced by a cascade of molecular events leading to nucleolysis by endonucleases and involves a number of membrane receptors and cytoplasmic proteins. These structures (including Fas, müllerian inhibiting substance, p53 and the c-myc oncogene) contribute, by interactive regulatory mechanisms, to the promotion or inhibition of apoptosis, on the basis of both external stimulus and cell activation state. Since apoptosis is a selective process to suppress defective cells, deregulation of genes encoding for such apoptosis-related proteins could be relevant in the growth of several tumors. Remarkably, overexpression of the bcl-2 gene in a few experimental lymphomas has been associated with neoplastic proliferation because of its inhibitory effect on apoptosis. Conversely, early activation of Fas, an apoptosis-inducing gene on HIV-infected CD4+ lymphocytes, is thought to aggravate T cell lymphopenia in HIV infection by increasing the level of normal apoptosis. Genetic deregulation of apoptosis has also been postulated in the pathogenesis of several diseases. Indeed, while preliminary studies suggest that apoptosis plays a role in autoimmune disorders including systemic lupus erythematosus, the pathogenesis of a few degenerative neuropathies, such as Alzheimer's disease, could depend on a similar altered mechanism in apoptosis of neuronal cells. However, no studies are presently available to suggest that exploitation of molecular events of apoptosis would imply therapeutic progress.
Insights
Apoptosis, programmed cell death, is crucial for eliminating abnormal cells. Its deregulation is implicated in diseases like cancer, HIV, and neurodegenerative conditions, but therapeutic applications remain unexplored.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Apoptosis is a genetically encoded, active cell death process essential for removing abnormal or unwanted cells.
- It involves molecular cascades, nucleolysis by endonucleases, and interactions between membrane receptors and cytoplasmic proteins.
- Key regulators include Fas, p53, c-myc, and bcl-2, which modulate apoptosis based on stimuli and cell state.
Purpose of the Study:
- To explore the role of apoptosis deregulation in various diseases.
- To highlight the implications of apoptosis in cancer, HIV infection, autoimmune disorders, and neurodegenerative diseases.
- To review the current understanding of apoptosis-related gene deregulation in disease pathogenesis.
Main Methods:
- Review of existing literature on apoptosis molecular mechanisms.
- Analysis of genetic regulation of apoptosis-related proteins.
- Examination of the role of apoptosis in specific disease contexts.
Main Results:
- Deregulation of apoptosis-related genes is linked to tumor growth, such as bcl-2 overexpression in lymphomas inhibiting apoptosis.
- Fas gene activation in HIV-infected T cells exacerbates lymphopenia by increasing normal apoptosis.
- Altered apoptosis mechanisms are postulated in autoimmune diseases (e.g., lupus) and neurodegenerative conditions (e.g., Alzheimer's disease).
Conclusions:
- Genetic deregulation of apoptosis is implicated in the pathogenesis of diverse diseases.
- While apoptosis plays a role in conditions like cancer and neurodegeneration, its therapeutic exploitation is not yet established.
- Further research is needed to understand and potentially target apoptosis for therapeutic benefit.