Transactivation
Encyclopedia
In molecular biology
and genetics
, transactivation is an increased rate of gene expression
triggered either by biological processes or by artificial means.
and HTLV are just two of the many viruses that encode transactivators to enhance their own gene expression. These transactivators can also be associated with cancer if they start interacting and increasing expression of a cellular proto-oncogene. HTLV for instance has been associated with causing leukemia
primarily through this process. Its transactivator (named tax) can interact with p40, causing overexpression of interleukin 2
, interleukin receptor
s, GM-CSF and the transcription factor
c-Fos
. HTLV infects T-cells and so, with increased expression of these stimulatory cytokines and transcription factors, leads to uncontrolled proliferation of T-cells and hence lymphoma
.
. The transactivator gene expresses
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 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 see when the transactivator is being expressed.
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...
and genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
, transactivation is an increased rate of gene expression
Gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...
triggered either by biological processes or by artificial means.
Natural transactivation
Transactivation can be triggered either by endogenous cellular or viral proteins, so-called transactivators. These protein factors act in trans (i.e., intermolecularly). HIVHIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
and HTLV are just two of the many viruses that encode transactivators to enhance their own gene expression. These transactivators can also be associated with cancer if they start interacting and increasing expression of a cellular proto-oncogene. HTLV for instance has been associated with causing leukemia
Leukemia
Leukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...
primarily through this process. Its transactivator (named tax) can interact with p40, causing overexpression of interleukin 2
Interleukin 2
Interleukin-2 is an interleukin, a type of cytokine immune system signaling molecule, which is a leukocytotrophic hormone that is instrumental in the body's natural response to microbial infection and in discriminating between foreign and self...
, interleukin receptor
Interleukin receptor
-Types:There are two main families of Interleukin receptors, type 1 and type 2 cytokine receptors.-Other:*Interleukin-1 receptor and interleukin-18 receptor belong to the immunoglobulin superfamily....
s, GM-CSF and the transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
c-Fos
C-Fos
In the field of molecular biology and Genetics, c-Fos is a protein encoded by the FOS gene.-Structure and function:c-Fos is a cellular proto-oncogene belonging to the immediate early gene family of transcription factors. c-Fos has a leucine-zipper DNA binding domain, and a transactivation domain at...
. HTLV infects T-cells and so, with increased expression of these stimulatory cytokines and transcription factors, leads to uncontrolled proliferation of T-cells and hence lymphoma
Lymphoma
Lymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...
.
Artificial transactivation
Artificial transactivation of a gene is achieved by inserting into the genome at the appropriate area a transactivator gene and special promoter regions of DNADNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
. The transactivator gene expresses
Gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...
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 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
Reporter gene
In molecular biology, a reporter gene is a gene that researchers attach to a regulatory sequence of another gene of interest in cell culture, animals or plants. Certain genes are chosen as reporters because the characteristics they confer on organisms expressing them are easily identified and...
, we can see when the transactivator is being expressed.