C-X-C chemokine receptor activity

Definition

Target type: molecularfunction

Combining with a C-X-C chemokine and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. A C-X-C chemokine has a single amino acid between the first two cysteines of the characteristic four cysteine motif. [GOC:signaling, PMID:8662823]

C-X-C chemokine receptor activity is a critical component of the immune system, playing a crucial role in the recruitment and activation of immune cells, particularly neutrophils, lymphocytes, and monocytes. These receptors, also known as CXCRs, are G protein-coupled receptors (GPCRs) located on the cell surface. They bind to a specific family of chemokines, small secreted proteins that act as chemoattractants and signaling molecules.

When a chemokine binds to its corresponding CXCR, a cascade of events is triggered within the cell. This begins with the activation of a heterotrimeric G protein, composed of alpha, beta, and gamma subunits. The activated G protein, specifically the alpha subunit, then initiates a signaling pathway that involves the production of second messengers, such as cyclic adenosine monophosphate (cAMP) and inositol triphosphate (IP3).

This signaling pathway ultimately leads to a variety of cellular responses, including:

* **Chemotaxis:** The primary function of CXCRs is to guide the movement of immune cells towards areas of inflammation or infection. Chemokines bind to CXCRs, generating a chemotactic gradient that directs the migration of cells along the gradient.
* **Cell activation:** CXCR activation can trigger the release of inflammatory mediators, such as cytokines and reactive oxygen species, by immune cells. This further contributes to the inflammatory response.
* **Adhesion:** CXCR activation can enhance the adhesion of immune cells to the endothelium, the lining of blood vessels, allowing them to exit the bloodstream and reach the site of inflammation.
* **Survival:** CXCR signaling can promote the survival of immune cells, preventing their apoptosis (programmed cell death).

The specific functions of CXCRs are highly dependent on the type of chemokine that binds to them and the cell type expressing the receptor. For example, CXCR1 and CXCR2 are primarily involved in the recruitment of neutrophils, while CXCR3 and CXCR4 play a role in the migration of lymphocytes and monocytes.

CXCRs are implicated in a wide range of physiological and pathological processes, including:

* **Inflammation:** CXCRs play a critical role in the initiation and resolution of inflammation. They are involved in the recruitment of immune cells to sites of infection and injury, as well as the regulation of inflammatory responses.
* **Immune surveillance:** CXCRs contribute to the immune system's ability to monitor the body for pathogens and other threats. They help to direct immune cells to areas of infection or damage, where they can initiate an immune response.
* **Wound healing:** CXCRs are involved in the recruitment of cells necessary for tissue repair and regeneration. They promote the migration of fibroblasts, epithelial cells, and other cells to the wound site, contributing to the healing process.
* **Cancer:** Some CXCRs are implicated in cancer progression and metastasis. They can contribute to the growth, spread, and survival of tumor cells by promoting angiogenesis (blood vessel formation) and immune evasion.
* **Autoimmunity:** Dysregulation of CXCR signaling can contribute to autoimmune diseases, such as rheumatoid arthritis and inflammatory bowel disease.

Understanding the molecular function of CXCRs is crucial for developing therapeutic strategies to target these receptors in various diseases. Antagonists, which block the activity of CXCRs, are being investigated as potential treatments for inflammatory diseases, autoimmune diseases, and cancer. Conversely, agonists, which activate CXCRs, are being explored for their potential to enhance the immune response against infections and tumors.'
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Proteins (6)

Compounds (59)