Fas ligand: Difference between revisions
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{{Short description|A protein involved in the regulation of the immune system}} | |||
{{DISPLAYTITLE:Fas Ligand}} | |||
== | ==Overview== | ||
Fas ligand is a type-II transmembrane protein, | [[Fas ligand]] (FasL) is a type-II transmembrane protein that belongs to the [[tumor necrosis factor]] (TNF) family. It plays a crucial role in the regulation of the [[immune system]] and the induction of [[apoptosis]], or programmed cell death. FasL is primarily expressed on the surface of activated [[T cells]] and [[natural killer cells]], and it interacts with its receptor, [[Fas receptor]] (FasR), to trigger apoptotic signaling pathways. | ||
== | ==Structure== | ||
Fas ligand is a homotrimeric protein, meaning it forms a complex of three identical subunits. Each subunit consists of an extracellular domain, a transmembrane domain, and a short cytoplasmic tail. The extracellular domain is responsible for binding to the Fas receptor, initiating the apoptotic cascade. | |||
Fas ligand is | ==Function== | ||
The primary function of Fas ligand is to induce apoptosis in target cells. This is a critical mechanism for maintaining immune homeostasis and preventing autoimmune diseases. When FasL binds to FasR on the surface of a target cell, it triggers a series of intracellular events that lead to cell death. This process is essential for the elimination of infected or cancerous cells and for the termination of immune responses. | |||
== Role in | ===Role in Immune System=== | ||
Fas ligand is involved in several key processes within the immune system: | |||
* '''Activation-Induced Cell Death (AICD):''' FasL is crucial for AICD, a process that helps regulate the immune response by eliminating excess [[lymphocytes]] after an immune response. | |||
* '''Peripheral Tolerance:''' FasL contributes to peripheral tolerance by inducing apoptosis in self-reactive T cells, thus preventing [[autoimmunity]]. | |||
* '''Cytotoxic T Lymphocyte (CTL) Function:''' CTLs use FasL to kill target cells, such as virus-infected cells or tumor cells, by inducing apoptosis. | |||
== | ==Pathology== | ||
Dysregulation of Fas ligand or its receptor can lead to various diseases: | |||
* '''Autoimmune Diseases:''' Insufficient FasL activity can result in the survival of self-reactive lymphocytes, contributing to autoimmune conditions such as [[systemic lupus erythematosus]] and [[rheumatoid arthritis]]. | |||
* '''Cancer:''' Some cancer cells evade immune surveillance by downregulating FasR or expressing FasL to induce apoptosis in attacking immune cells. | |||
* '''Immunodeficiency:''' Mutations in the Fas or FasL genes can lead to immunodeficiency syndromes, characterized by lymphoproliferation and increased susceptibility to infections. | |||
==Clinical Applications== | |||
Understanding the Fas/FasL system has implications for therapeutic interventions: | |||
* '''Cancer Therapy:''' Strategies to enhance FasL-mediated apoptosis in tumor cells are being explored as potential cancer treatments. | |||
* '''Autoimmune Disease Treatment:''' Modulating FasL activity could help in treating autoimmune diseases by promoting the deletion of autoreactive lymphocytes. | |||
==Images== | |||
[[File:FasL_structure.png|thumb|right|Diagram of Fas ligand structure showing its trimeric form.]] | |||
[[File:FasL_pathway.png|thumb|left|Illustration of the Fas/FasL apoptotic pathway.]] | |||
==Related pages== | |||
* [[Apoptosis]] | * [[Apoptosis]] | ||
* [[ | * [[Tumor necrosis factor]] | ||
* [[ | * [[Immune system]] | ||
* [[ | * [[T cell]] | ||
* [[ | * [[Natural killer cell]] | ||
[[Category:Immunology]] | |||
[[Category:Proteins]] | [[Category:Proteins]] | ||
[[Category:Apoptosis]] | [[Category:Apoptosis]] | ||
Revision as of 17:33, 18 February 2025
A protein involved in the regulation of the immune system
Overview
Fas ligand (FasL) is a type-II transmembrane protein that belongs to the tumor necrosis factor (TNF) family. It plays a crucial role in the regulation of the immune system and the induction of apoptosis, or programmed cell death. FasL is primarily expressed on the surface of activated T cells and natural killer cells, and it interacts with its receptor, Fas receptor (FasR), to trigger apoptotic signaling pathways.
Structure
Fas ligand is a homotrimeric protein, meaning it forms a complex of three identical subunits. Each subunit consists of an extracellular domain, a transmembrane domain, and a short cytoplasmic tail. The extracellular domain is responsible for binding to the Fas receptor, initiating the apoptotic cascade.
Function
The primary function of Fas ligand is to induce apoptosis in target cells. This is a critical mechanism for maintaining immune homeostasis and preventing autoimmune diseases. When FasL binds to FasR on the surface of a target cell, it triggers a series of intracellular events that lead to cell death. This process is essential for the elimination of infected or cancerous cells and for the termination of immune responses.
Role in Immune System
Fas ligand is involved in several key processes within the immune system:
- Activation-Induced Cell Death (AICD): FasL is crucial for AICD, a process that helps regulate the immune response by eliminating excess lymphocytes after an immune response.
- Peripheral Tolerance: FasL contributes to peripheral tolerance by inducing apoptosis in self-reactive T cells, thus preventing autoimmunity.
- Cytotoxic T Lymphocyte (CTL) Function: CTLs use FasL to kill target cells, such as virus-infected cells or tumor cells, by inducing apoptosis.
Pathology
Dysregulation of Fas ligand or its receptor can lead to various diseases:
- Autoimmune Diseases: Insufficient FasL activity can result in the survival of self-reactive lymphocytes, contributing to autoimmune conditions such as systemic lupus erythematosus and rheumatoid arthritis.
- Cancer: Some cancer cells evade immune surveillance by downregulating FasR or expressing FasL to induce apoptosis in attacking immune cells.
- Immunodeficiency: Mutations in the Fas or FasL genes can lead to immunodeficiency syndromes, characterized by lymphoproliferation and increased susceptibility to infections.
Clinical Applications
Understanding the Fas/FasL system has implications for therapeutic interventions:
- Cancer Therapy: Strategies to enhance FasL-mediated apoptosis in tumor cells are being explored as potential cancer treatments.
- Autoimmune Disease Treatment: Modulating FasL activity could help in treating autoimmune diseases by promoting the deletion of autoreactive lymphocytes.
