Tamoxifen-induced gene expression
Tamoxifen-induced gene expression is a method used in molecular biology and neuroscience to activate transcription of a specific gene by application of the drug tamoxifen. It is based on the expression of a mutated estrogen receptor (ERT2) fused to Cre recombinase.[1] In the absence of tamoxifen, the receptor is inactive and sequestered in the cytoplasm. When tamoxifen is administered, it binds to ERT2, causing the Cre-ERT2 fusion protein to move into the cell's nucleus, where it can perform its recombination function. The gene of interest, encoding e.g. the fluorescent protein GFP, contains a LoxP-flanked stop cassette that prevents expression unless it is excised by Cre recombinase.[2]
When used in mice, the Cre-ERT2 system allows for excellent temporal control: Administration of tamoxifen triggers genetic changes at a precise time point in development or adult life. However, depending on the type of target cell, the gene of interest may not be successfully activated in every cell, leading to mosaic expression.
TRAP2 mice to label active neurons
The Cre-ERT2 system has been harnessed to express genes of interest, e.g. fluorescent markers or optogenetic tools, in highly active neurons. For this purpose, it is driven by the immediate early gene Fos.[3][4] This approach, called Targeted Recombination in Active Populations (TRAP, TRAP2), is used to investigate learning and memory in mice on the cellular level.[5][6][7]
See also
- Tetracycline-controlled transcriptional activation, an alternative method to activate genes using the antibiotic tetracycline. Note that dependent on dosage, mouse strain and sex, both tetracycline and tamoxifen can alter the behavior of mice.[8][9]
- TetTag mice use the tetracycline transactivator to label Fos-expressing neurons.
References
- ^ Zhao, Jing; Nassar, Mohammed A.; Gavazzi, Isabella; Wood, John N. (2006). "Tamoxifen-inducible Na V 1.8-CreERT2 recombinase activity in nociceptive neurons of dorsal root ganglia". Genesis. 44 (8): 364–371. doi:10.1002/dvg.20224. ISSN 1526-954X. PMID 16850455.
- ^ Sapkota, Darshan; Dougherty, Joseph D. (2020-02-20). "An inducible Cre mouse line to sparsely target nervous system cells, including Remak Schwann cells". Neural Development. 15 (1) 2. doi:10.1186/s13064-020-00140-y. ISSN 1749-8104. PMC 7031956. PMID 32079539.
- ^ Allen, William E.; DeNardo, Laura A.; Chen, Michael Z.; Liu, Cindy D.; Loh, Kyle M.; Fenno, Lief E.; Ramakrishnan, Charu; Deisseroth, Karl; Luo, Liqun (2017-09-15). "Thirst-associated preoptic neurons encode an aversive motivational drive". Science. 357 (6356): 1149–1155. Bibcode:2017Sci...357.1149A. doi:10.1126/science.aan6747. ISSN 0036-8075. PMC 5723384. PMID 28912243.
- ^ Guenthner, Casey J; Miyamichi, Kazunari; Yang, Helen H; Heller H, Craig; Luo, Liqun (2013). "Permanent Genetic Access to Transiently Active Neurons via TRAP: Targeted Recombination in Active Populations". Neuron. 78 (5): 773–784. doi:10.1016/j.neuron.2013.03.025. PMC 3782391. PMID 23764283.
- ^ DeNardo, Laura A.; Liu, Cindy D.; Allen, William E.; Adams, Eliza L.; Friedmann, Drew; Fu, Lisa; Guenthner, Casey J.; Tessier-Lavigne, Marc; Luo, Liqun (2019). "Temporal evolution of cortical ensembles promoting remote memory retrieval". Nature Neuroscience. 22 (3): 460–469. doi:10.1038/s41593-018-0318-7. ISSN 1097-6256. PMC 6387639. PMID 30692687.
- ^ Chen, Michelle B.; Jiang, Xian; Quake, Stephen R.; Südhof, Thomas C. (2020-11-11). "Persistent transcriptional programmes are associated with remote memory". Nature. 587 (7834): 437–442. Bibcode:2020Natur.587..437C. doi:10.1038/s41586-020-2905-5. ISSN 0028-0836. PMC 9097329. PMID 33177708.
- ^ Mocle, Andrew J.; Ramsaran, Adam I.; Jacob, Alexander D.; Rashid, Asim J.; Luchetti, Alessandro; Tran, Lina M.; Richards, Blake A.; Frankland, Paul W.; Josselyn, Sheena A. (2024). "Excitability mediates allocation of pre-configured ensembles to a hippocampal engram supporting contextual conditioned threat in mice". Neuron. 112 (9): 1487–1497.e6. doi:10.1016/j.neuron.2024.02.007. ISSN 0896-6273. PMC 11065628. PMID 38447576.
- ^ Xu, Ru-Xia; Liao, Shi-Han; Wang, Nan; Jiang, Wen-Ying; Wang, Xun; Li, Xiao-Wen; Gao, Tian-Ming; Yang, Jian-Ming (2025-12-10). "Sex-dependent effects of tamoxifen on mouse behavior". Behavioral and Brain Functions. doi:10.1186/s12993-025-00312-y. ISSN 1744-9081. PMID 41366492.
- ^ Han, H. J.; Allen, C. C.; Buchovecky, C. M.; Yetman, M. J.; Born, H. A.; Marin, M. A.; Rodgers, S. P.; Song, B. J.; Lu, H.-C.; Justice, M. J.; Probst, F. J.; Jankowsky, J. L. (2012-08-01). "Strain Background Influences Neurotoxicity and Behavioral Abnormalities in Mice Expressing the Tetracycline Transactivator". Journal of Neuroscience. 32 (31): 10574–10586. doi:10.1523/JNEUROSCI.0893-12.2012. ISSN 0270-6474. PMC 3431916. PMID 22855807.
External links
- A CreERT2 mouse was developed by Artemis Pharmaceuticals (now Taconic Biosciences)
- TRAP2 mice are available at Jackson Labs