cellular response to xenobiotic stimulus

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus from a xenobiotic, a compound foreign to the organism exposed to it. It may be synthesized by another organism (like ampicilin) or it can be a synthetic chemical. [GOC:krc, GOC:mah]

Cellular response to xenobiotic stimulus is a complex and essential process that allows cells to cope with the presence of foreign compounds. Xenobiotics are chemicals that are not naturally produced by the body, such as drugs, pesticides, pollutants, and food additives. These compounds can have various effects on cells, ranging from mild to severe, depending on their chemical structure, concentration, and duration of exposure. To protect themselves from these potentially harmful substances, cells have evolved sophisticated mechanisms to detect, process, and eliminate xenobiotics. This intricate process involves a series of coordinated steps, including:

1. **Xenobiotic uptake and transport:** The first step in cellular response to xenobiotics is their entry into the cell. This can occur through passive diffusion across the cell membrane, active transport by membrane proteins, or endocytosis. Once inside the cell, xenobiotics may be transported to specific organelles, such as the endoplasmic reticulum (ER) or mitochondria, where they can be metabolized or sequestered.

2. **Xenobiotic sensing and signaling:** Cells possess specialized receptors and signaling pathways that detect the presence of xenobiotics. These receptors can be located on the cell surface, within the cytoplasm, or in the nucleus. Upon binding to xenobiotics, these receptors trigger intracellular signaling cascades, leading to the activation of transcription factors and the expression of genes involved in xenobiotic detoxification and cellular protection.

3. **Xenobiotic metabolism and detoxification:** The primary mechanism for eliminating xenobiotics is through metabolic transformation. This process involves a series of enzymatic reactions that convert xenobiotics into more water-soluble and excretable forms. The major enzymes involved in xenobiotic metabolism include cytochrome P450s, glutathione S-transferases, and UDP-glucuronosyltransferases. These enzymes can catalyze a variety of reactions, such as oxidation, reduction, hydroxylation, and conjugation, to modify the structure of xenobiotics and facilitate their elimination from the body.

4. **Xenobiotic efflux and excretion:** Once metabolized, xenobiotics are often transported out of the cell by efflux pumps, such as P-glycoprotein and multidrug resistance-associated proteins. These transporters actively pump xenobiotics across the cell membrane and into the extracellular space, where they can be excreted through urine, feces, or bile.

5. **Cellular defense and repair:** In addition to detoxification, cells have evolved mechanisms to protect themselves from the damaging effects of xenobiotics. These mechanisms include antioxidant defenses, DNA repair systems, and apoptosis. Antioxidants, such as glutathione and superoxide dismutase, scavenge reactive oxygen species (ROS) generated by xenobiotic metabolism. DNA repair pathways repair damage to DNA caused by xenobiotics. Apoptosis, or programmed cell death, eliminates cells that have sustained irreparable damage from xenobiotic exposure.

The cellular response to xenobiotic stimulus is essential for maintaining cellular homeostasis and protecting against toxicity. These complex and tightly regulated processes ensure that cells can effectively handle foreign compounds and maintain their integrity in the presence of xenobiotic stress.'
"

Proteins (35)

Compounds (3,376)