cell-cell signaling

Definition

Target type: biologicalprocess

Any process that mediates the transfer of information from one cell to another. This process includes signal transduction in the receiving cell and, where applicable, release of a ligand and any processes that actively facilitate its transport and presentation to the receiving cell. Examples include signaling via soluble ligands, via cell adhesion molecules and via gap junctions. [GOC:dos, GOC:mah]

Cell-cell signaling is a fundamental process in multicellular organisms that allows cells to communicate with each other and coordinate their activities. It involves the transmission of signals between cells, which can be chemical, electrical, or mechanical. These signals trigger specific responses in the receiving cells, altering their behavior, growth, and differentiation. Here's a detailed breakdown of the process:

1. **Signal Production and Release:**
- The signaling process begins with a signaling cell that produces and releases a signaling molecule, also known as a ligand.
- Ligands can be proteins, peptides, lipids, or even gases.
- The method of release varies. Some ligands are secreted directly into the extracellular space, while others are displayed on the surface of the signaling cell.

2. **Signal Reception:**
- The signaling molecule travels to the target cell and binds to a specific receptor protein on its surface.
- Receptors are transmembrane proteins that have an extracellular domain that binds to the ligand and an intracellular domain that initiates the signaling cascade.
- Different receptors have different binding affinities for specific ligands, ensuring specificity in the signaling process.

3. **Signal Transduction:**
- Upon ligand binding, the receptor undergoes a conformational change, activating its intracellular domain.
- This activation triggers a cascade of intracellular signaling events.
- The signal is relayed through a series of signaling molecules within the target cell, often involving protein kinases and phosphatases, second messengers (such as cAMP, calcium ions, or diacylglycerol), and protein-protein interactions.

4. **Signal Amplification:**
- The signaling cascade can amplify the initial signal.
- One activated molecule can activate multiple downstream molecules, leading to a rapid and significant response in the cell.

5. **Signal Integration:**
- Multiple signaling pathways can converge on a single target protein or pathway, allowing the cell to integrate information from different sources.
- This allows for coordinated responses to a variety of stimuli.

6. **Signal Termination:**
- The signaling process must be carefully regulated to avoid prolonged or inappropriate responses.
- This is achieved through mechanisms that terminate the signal, such as the degradation of the ligand, the removal of the receptor from the cell surface, or the inactivation of signaling proteins within the cell.

7. **Cellular Response:**
- The ultimate outcome of cell-cell signaling is a specific cellular response.
- This response can range from changes in gene expression to altered protein activity or changes in cell shape or movement.
- The type of response depends on the specific signaling pathway and the target cell's internal machinery.

**Examples of Cell-Cell Signaling Processes:**

- **Neurotransmission:** Signals are transmitted between neurons via neurotransmitters released at synapses.
- **Hormonal Signaling:** Hormones, secreted by endocrine glands, travel through the bloodstream to reach target cells throughout the body.
- **Immune Response:** Immune cells communicate with each other through cytokines and chemokines, coordinating the defense against pathogens.
- **Development and Differentiation:** Signaling pathways play crucial roles in embryonic development, guiding cell fate and tissue formation.

Cell-cell signaling is an essential process that underlies a wide range of biological functions, from simple cellular processes to complex organismal behavior. It is a highly regulated and sophisticated system that allows cells to communicate and coordinate their activities in a dynamic and efficient manner.'
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Proteins (42)

Compounds (968)