Biology · BEGINNER LESSON
Upregulation
Upregulation is a biological increase in response to an outside signal, or a rise in gene expression or protein activity. In cells, it can mean making a cell more sensitive to a signal or making more RNA or protein from a gene.
What it is
Upregulation is a change in which a cell responds more strongly to something outside it, such as a hormone or drug. In gene regulation, it can also mean that a gene is expressed at a higher level, producing more messenger RNA (mRNA, the RNA copy used to make protein) and often more protein.
[1] Definition of upregulation - NCI Dictionary of Cancer Terms [2] Modulating gene regulation to treat genetic disorders - PMC - NIH
How it happens
One way a cell upregulates its response is by increasing the number or activity of receptors, which are molecules on the cell surface that bind signals. Another way is by changing gene-regulatory elements, such as promoters, enhancers, or silencers. A promoter is a DNA region that starts transcription, which is the making of RNA from DNA. An enhancer helps turn a promoter on, while a silencer shuts it down.
[1] Definition of upregulation - NCI Dictionary of Cancer Terms [2] Modulating gene regulation to treat genetic disorders - PMC - NIH
Mechanism in force-responsive genes
In one study, force applied through integrins, which are cell-surface proteins that connect cells to their surroundings, rapidly upregulated some genes. This increase in transcription depended on demethylation of H3K9me3, a chemical change on histone H3 that affected recruitment of RNA polymerase II (Pol II), the enzyme that makes RNA. When H3K9me3 was high, Pol II recruitment was blocked and upregulation did not occur in the same way.
[3] Force-induced gene up-regulation does not follow the ...
Limitations and cautions
Upregulation is not always beneficial. Gene expression can be too low or too high, and the useful range may differ by tissue. The sources also note that strong upregulation beyond a certain threshold can have harmful effects, and that high force frequency did not produce the same rapid transcription response as low frequency in the study described.
[2] Modulating gene regulation to treat genetic disorders - PMC - NIH [3] Force-induced gene up-regulation does not follow the ...
Evidence from the sources
The public sources define upregulation both as increased cellular response to a signal and as increased gene expression. They also show concrete examples: more surface receptors can make a cell more sensitive to a hormone or drug, and changes in promoter state or histone methylation can increase transcription of specific genes.
[1] Definition of upregulation - NCI Dictionary of Cancer Terms [2] Modulating gene regulation to treat genetic disorders - PMC - NIH [3] Force-induced gene up-regulation does not follow the ...
SEE THE IDEA
Simple view of upregulation
A hormone, drug, or physical force reaches the cell.
The cell may add receptors or change gene-regulatory activity.
A promoter becomes more active and RNA production increases.
More protein or a stronger response can result.
A signal outside the cell can trigger receptor changes or gene-regulatory changes that increase transcription and cell response.
Upregulation can happen at the cell surface or at the DNA level, leading to a stronger biological response.
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Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.