CD300E molecule | Elisa - Clia - Antibody - Protein

Background

CD300E, also known as immune receptor expressed by myeloid cells 3 (IREM-3), is a member of the CD300 family of immunoreceptors. These receptors play pivotal roles in the regulation of immune responses, interacting with both activating and inhibitory molecules to maintain immune homeostasis. CD300E is encoded by the CD300E gene located on chromosome 17q25.1, within a cluster of genes that encode other CD300 family members.

CD300E is primarily expressed on myeloid cells, including monocytes, macrophages, and dendritic cells. It functions as an activating receptor and is involved in the modulation of immune responses, particularly in the context of inflammation and pathogen defense.

Protein Structure

The CD300E protein is a type I transmembrane glycoprotein characterized by the following structural features:

• Extracellular Domain: The extracellular region of CD300E contains a single immunoglobulin (Ig)-like domain. This domain is critical for the recognition and binding of specific ligands, facilitating the receptor's role in immune activation.
• Transmembrane Region: This hydrophobic region anchors CD300E to the cell membrane, playing a vital role in its localization and function.
• Cytoplasmic Tail: The cytoplasmic tail of CD300E contains an immunoreceptor tyrosine-based activation motif (ITAM). This ITAM is essential for transducing activating signals upon ligand binding, leading to the recruitment of downstream signaling molecules and the initiation of immune responses.

Classification and Subtypes

CD300E belongs to the CD300 family, which includes both activating and inhibitory receptors that regulate immune responses. Members of this family can be classified based on the presence of ITIMs (inhibitory) or ITAMs (activating) in their cytoplasmic tails:

• Activating Receptors: These receptors, such as CD300E, contain ITAMs that deliver activating signals, promoting immune cell activation and response to pathogens. Other activating members include CD300B and CD300H.
• Inhibitory Receptors: These receptors, such as CD300A, contain ITIMs that deliver inhibitory signals, dampening immune responses to prevent excessive inflammation. CD300F is another example of an inhibitory receptor in this family.

The CD300 family members are structurally similar but have distinct functions, allowing them to fine-tune immune responses through both activation and inhibition.

Function and Biological Significance

CD300E is primarily involved in the activation of immune responses and plays several critical roles in immune regulation:

1. Activation of Myeloid Cells: CD300E is expressed on myeloid cells such as monocytes, macrophages, and dendritic cells. Its activation leads to the phosphorylation of the ITAM in its cytoplasmic tail, triggering a cascade of signaling events. These events result in the activation of the NF-κB pathway, which enhances the production of pro-inflammatory cytokines and promotes the immune response.
2. Enhancement of Phagocytosis: CD300E activation enhances the phagocytic capabilities of macrophages and dendritic cells. This increased phagocytosis is crucial for the clearance of pathogens and apoptotic cells, contributing to the resolution of infections and inflammation.
3. Cytokine Production: Upon activation, CD300E-expressing cells produce a variety of cytokines, including TNF-α, IL-6, and IL-12. These cytokines play essential roles in orchestrating the immune response, including the activation and recruitment of other immune cells to the site of infection or inflammation.
4. Role in Inflammatory Responses: CD300E is involved in the regulation of inflammatory responses. Its activation can amplify inflammation by promoting cytokine production and immune cell recruitment. However, this function must be tightly regulated to prevent excessive inflammation that can lead to tissue damage.
5. Interaction with Lipid Ligands: Similar to other CD300 family members, CD300E can interact with specific lipid ligands, such as phosphatidylserine and phosphatidylethanolamine. These interactions are important for the recognition of apoptotic cells and the regulation of immune responses.

Clinical Issues

CD300E's role in immune regulation has implications for various clinical conditions, particularly those involving inflammation and immune dysfunction:

1. Autoimmune Diseases: Dysregulation of CD300E expression or function can contribute to autoimmune diseases. Overactivation of immune responses through CD300E can lead to chronic inflammation and tissue damage, characteristic of autoimmune disorders such as rheumatoid arthritis and systemic lupus erythematosus.
2. Infectious Diseases: CD300E plays a role in the immune response to infections. Its activation enhances the ability of myeloid cells to clear pathogens, but excessive activation can also result in tissue damage and exacerbation of inflammatory responses. Understanding CD300E's role in infectious diseases could inform therapeutic strategies aimed at modulating immune responses.
3. Inflammatory Conditions: Given its role in promoting inflammatory responses, CD300E is implicated in various inflammatory conditions. Targeting CD300E-mediated pathways could offer therapeutic potential in managing chronic inflammation associated with diseases such as inflammatory bowel disease and chronic obstructive pulmonary disease.
4. Cancer: The role of CD300E in cancer is complex and context-dependent. While its activation can enhance anti-tumor immunity by promoting the activation of immune cells, chronic activation of CD300E may also contribute to a pro-inflammatory environment that supports tumor growth and metastasis. Further research is needed to elucidate the precise role of CD300E in cancer and its potential as a therapeutic target.

Summary

CD300E is an important activating receptor in the CD300 family, predominantly expressed on myeloid cells. Structurally, it features an extracellular Ig-like domain, a transmembrane region, and a cytoplasmic tail with an ITAM that mediates activating signals. CD300E plays significant roles in activating immune responses, enhancing phagocytosis, and promoting cytokine production. Its involvement in various clinical conditions, including autoimmune diseases, infections, inflammatory conditions, and cancer, underscores its importance in immune regulation. Understanding the precise mechanisms of CD300E's function and its interactions with other immune molecules is essential for developing targeted therapies aimed at modulating immune responses in diverse diseases.