Trans-activation response element (TAR)
Encyclopedia
The HIV
trans-activation response (TAR) element is an RNA element
which is known to be required for the trans-activation of the viral promoter and for virus replication. The TAR hairpin
acts as a binding site for the Tat protein
and this interaction stimulates the activity of the long terminal repeat
promoter.
Further analysis has shown that TAR is a pre-microRNA that produces mature microRNAs from both strands of the TAR stem-loop.
These miRNAs are thought to prevent infected cells from under-going apoptosis
by down-regulating the genes ERCC1
and IER3
.
HIV
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...
trans-activation response (TAR) element is an RNA element
Cis-regulatory element
A cis-regulatory element or cis-element is a region of DNA or RNA that regulates the expression of genes located on that same molecule of DNA . This term is constructed from the Latin word cis, which means "on the same side as". These cis-regulatory elements are often binding sites for one or...
which is known to be required for the trans-activation of the viral promoter and for virus replication. The TAR hairpin
Stem-loop
Stem-loop intramolecular base pairing is a pattern that can occur in single-stranded DNA or, more commonly, in RNA. The structure is also known as a hairpin or hairpin loop. It occurs when two regions of the same strand, usually complementary in nucleotide sequence when read in opposite directions,...
acts as a binding site for the Tat protein
Tat (HIV)
Tat is an HIV gene.Tat stands for "Trans-Activator of Transcription". Tat consists of between 86 and 101 amino acids depending on the subtype.-Function:...
and this interaction stimulates the activity of the long terminal repeat
Long terminal repeat
Long terminal repeats are sequences of DNA that repeat hundreds or thousands of times. They are found in retroviral DNA and in retrotransposons, flanking functional genes...
promoter.
Further analysis has shown that TAR is a pre-microRNA that produces mature microRNAs from both strands of the TAR stem-loop.
These miRNAs are thought to prevent infected cells from under-going apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
by down-regulating the genes ERCC1
ERCC1
DNA excision repair protein ERCC-1 is a protein that in humans is encoded by the ERCC1 gene.- Function :The function of the ERCC1 protein is predominantly in nucleotide excision repair of damaged DNA...
and IER3
IER3
Radiation-inducible immediate-early gene IEX-1 is a protein that in humans is encoded by the IER3 gene.-Further reading:...
.