In the context of gene regulation:
transactivation is the increased rate of
gene expression triggered either by biological processes or by artificial means, through the expression of an intermediate transactivator protein.
In the context of receptor signaling, transactivation occurs when one or more receptors activate yet another;
Natural transactivation
Transactivation can be triggered either by endogenous cellular or viral proteins, also called
transactivators. These protein factors
Trans acting (
i.e.,
).
HIV and
HTLV are just two of the many viruses that encode transactivators to enhance viral gene expression. These transactivators can also be linked to cancer if they start interacting with, and increasing expression of, a cellular
proto-oncogene. HTLV, for instance, has been associated with causing
leukemia primarily through this process. Its transactivator,
Tax , can interact with p40, inducing overexpression of interleukin 2, interleukin receptors,
GM-CSF and the transcription factor
c-Fos. HTLV infects
and via the increased expression of these stimulatory
cytokines and transcription factors, leads to uncontrolled proliferation of T-cells and hence
lymphoma.
Artificial transactivation
Artificial transactivation of a gene is achieved by inserting it into the genome at the appropriate area as transactivator gene adjoined to special promoter regions of
DNA. The transactivator gene
Gene expression a transcription factor that binds to specific promoter region of DNA. By binding to the
promoter region of a gene, the transcription factor causes that gene to be expressed. The expression of one transactivator gene can activate multiple genes, as long as they have the same, specific promoter region attached. Because the expression of the transactivator gene can be controlled, transactivation can be used to turn genes on and off. If this specific promoter region is also attached to a
reporter gene, we can measure when the transactivator is being expressed.
See also
External links
