upregulate

Upregulate is a biological term meaning to increase the quantity or activity of a molecule within a cell or tissue. This can involve raising levels of gene expression, producing more mRNA and protein, or increasing the number or activity of receptors, enzymes, or signaling components. Upregulation is a common adaptive response to changes in the cellular environment, such as reduced ligand availability, sustained stimulation, stress, or developmental cues.

Mechanisms behind upregulation can occur at multiple levels. Transcriptional upregulation increases the rate of gene transcription, often via transcription factors and chromatin changes. Post-transcriptional processes can stabilize mRNA or enhance its translation. Post-translational mechanisms may stabilize the protein, increase its activity, or promote trafficking to functional locations, such as moving receptors to the cell surface to raise signaling capacity. In many cases, receptors are mobilized from intracellular stores to the plasma membrane, increasing receptor density.

Contexts and examples include receptor upregulation in response to chronic receptor antagonists or low ligand levels, which can alter cellular sensitivity. Immune and endocrine systems also exhibit upregulation, such as increased expression of surface molecules on activated immune cells or changes in enzymes and transporters in metabolic pathways.

Upregulation is often discussed in contrast to downregulation, which decreases expression or activity. The term upregulation is frequently encountered in pharmacology, physiology, and gene regulation to describe adaptive increases in cellular components.