trans-activation response element

{{Infobox rfam

| Name = Trans-activation response element (TAR)

| image = RF00250.jpg

| width =

| caption = Predicted secondary structure and sequence conservation of mir-TAR

| Symbol = mir-TAR

| AltSymbols = TAR

| Rfam = RF00250

| miRBase =

| miRBase_family =

| RNA_type = Gene; miRNA

| Tax_domain = Viruses

| GO = {{GO|0035068}} {{GO|0035195}}

| SO = {{SO|0000233}} {{SO|0001244}}

| CAS_number =

| EntrezGene =

| HGNCid =

| OMIM =

| PDB =

| RefSeq =

| Chromosome =

| Arm =

| Band =

| LocusSupplementaryData =

}}

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 is a dynamic structure{{cite journal|last1=Lu|first1=Jia|last2=Kadakkuzha|first2=Beena M.|last3=Zhao|first3=Liang|title=Dynamic Ensemble View of the Conformational Landscape of HIV-1 TAR RNA and Allosteric Recognition|journal=Biochemistry|date=2011|volume=50|issue=22|pages=5042–5057|pmid=21553929|doi=10.1021/bi200495d |display-authors=etal}} that acts as a binding site for the Tat protein, and this interaction stimulates the activity of the long terminal repeat promoter.{{cite journal | last = Kulinski | first = T |author2=Olejniczak M |author3=Huthoff H |author4=Bielecki L |author5=Pachulska-Wieczorek K |author6=Das AT |author7=Berkhout B |author8=Adamiak RW | year = 2003 | title = The apical loop of the HIV-1 TAR RNA hairpin is stabilized by a cross-loop base pair | journal = J Biol Chem | volume = 278 | pages = 38892–38901 | pmid = 12882959 | doi = 10.1074/jbc.M301939200 | issue = 40| doi-access = free }}

Further analysis has shown that TAR is a pre-microRNA that produces mature microRNAs from both strands of the TAR stem-loop.{{cite journal |vauthors=Ouellet DL, Plante I, Landry P, etal |title=Identification of functional microRNAs released through asymmetrical processing of HIV-1 TAR element |journal=Nucleic Acids Res. |volume=36 |issue=7 |pages=2353–2365 |date=April 2008 |pmid=18299284 |pmc=2367715 |doi=10.1093/nar/gkn076 |url=}}

These miRNAs are thought to prevent infected cells from undergoing apoptosis by downregulating the genes ERCC1, IER3,{{cite journal |vauthors=Klase Z, Winograd R, Davis J, et al. |title=HIV-1 TAR miRNA protects against apoptosis by altering cellular gene expression |journal=Retrovirology |volume=6 |pages=18 |year=2009 |pmid=19220914 |pmc=2654423 |doi=10.1186/1742-4690-6-18 |doi-access=free }} CDK9, and Bim.{{cite journal|last1=Narayanan|first1=A|last2=Iordanskiy|first2=S|last3=Das|first3=R|last4=Van Duyne|first4=R|last5=Santos|first5=S|last6=Jaworski|first6=E|last7=Guendel|first7=I|last8=Sampey|first8=G|last9=Dalby|first9=E|last10=Iglesias-Ussel|first10=M|last11=Popratiloff|first11=A|last12=Hakami|first12=R|last13=Kehn-Hall|first13=K|last14=Young|first14=M|last15=Subra|first15=C|last16=Gilbert|first16=C|last17=Bailey|first17=C|last18=Romerio|first18=F|last19=Kashanchi|first19=F|title=Exosomes derived from HIV-1-infected cells contain trans-activation response element RNA.|journal=The Journal of Biological Chemistry|date=5 July 2013|volume=288|issue=27|pages=20014–20033|pmid=23661700|doi=10.1074/jbc.m112.438895|pmc=3707700|doi-access=free}}

Human polyomavirus 2 (JC virus) contains a TAR-homologous sequence in its late promoter{{cite journal |last1=Chowdhury|first1=Mashiul|last2=Taylor|first2=J. Paul|last3=Chang|first3=Chun-Fan|last4=Rappaport|first4=Jay|last5=Khalili|first5=Kamel|title=Evidence that a Sequence Similar to TAR Is Important for Induction of the JC Virus Late Promoter by Human Immunodeficiency Virus Type 1 Tat|year=1992|journal=Journal of Virology|volume=66|issue=12|pages=7355–7361|doi=10.1128/jvi.66.12.7355-7361.1992|doi-access=free|pmid=1331525|pmc=240440}} that is responsive to HIV-1 derived Tat.{{cite journal |last1=Nukuzuma|first1=Souichi|last2=Kameoka|first2=Masanori|last3=Sugiura|first3=Shigeki|last4=Nakamichi|first4=Kazuo|last5=Nukuzuma|first5=Chiyoko|last6=Miyoshi|first6=Isao|last7=Takegami|first7=Tsutomu|title=Exogenous human immunodeficiency virus-1 protein, Tat, enhances replication of JC virus efficiently in neuroblastoma cell lines|journal=Journal of Medical Virology|volume=84|issue=4|year=2012|pages=555–561|doi=10.1002/jmv.23239|pmid=22337293|s2cid=35625307 }}{{cite journal |last1=Krachmarov|first1=Chavdar P.|last2=Chepenik|first2=Lara G.|last3=Barr-Vagell|first3=Sharon|last4=Khalili|first4=Kamel|last5=Johnson|first5=Edward M.|title=Activation of the JC virus Tat-responsive transcriptional control element by association of the Tat protein of human immunodeficiency virus 1 with cellular protein Purα|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=93|issue=24|pages=14112–14117|doi=10.1073/pnas.93.24.14112|doi-access=free|pmid=8943069|pmc=34556|year=1996|bibcode=1996PNAS...9314112K }}