Custom Model Generation

Knockdown Mice

RNA interference and inducible/reversible miRNA expression can silence or activate almost any gene of interest, giving you precise control over in vivo gene expression. This has exciting applications for discovering new gene therapies.

  • Manually control gene activity
  • Generate inducible or reversible knockdown mice
  • Mimic the action of antagonistic drugs
  • Silence genes that are difficult or impossible to knockout

Precise vector construction is the key to successful knockdown model generation. Taconic Biosciences' vector construction team is among the most experienced in the industry, and all vectors are fully sequenced prior to electroporation.

Mouse in gloved hand

miRNA and RNAi Knockdown Mice

Inducible & Reversible miRNA Models

MicroRNAs (miRNAs) are naturally occurring, post-transcriptional regulators which silence genes by binding to complementary sequences in a target mRNA. Each individual miRNA may act to repress hundreds of target mRNAs.

Studies suggest that over 1,000 miRNAs are present in the human genome and may target 60% of mammalian genes.

Taconic offers inducible and reversible miRNA expressing mouse models. Similar to shRNA knockdown mice, your miRNA of choice is only (over)expressed when doxycycline is administered. Withdrawal of doxycycline inhibits ectopic miRNA expression.

Taconic's inducible miRNA expressing knockdown mice are an invaluable tool to study the effect of activating or silencing target genes in vivo.

reversible induction diagram

miRNA-Mediated Gene Knockdown

In the absence of an inducer (doxycycline), the tet-repressor protein binds to the tet-operator control element and effectively inhibits miRNA expression from the H1 promoter. When doxycycline is administered through an animal's feed or drinking water, it binds to the tet-repressor protein and blocks its interaction with the H1 promoter. This is followed by H1 promoter activation, miRNA expression, and effective RNA mediated gene knockdown.

Withdrawal of doxycycline inhibits miRNA expression resulting in pre-knockdown levels of target gene expression.

Northern Blot Analysis of miRNA Expression

Northern blot analysis demonstrates that, in the absence of doxycycline, levels of specific miRNA expression in wild type and miRNA gene knockdown models are equivalent. Following one day of doxycycline administration, increased expression of miRNA in a gene knockdown model is apparent. Maximum miRNA expression is achieved following eight days administration of doxycycline.

Similar levels of 5S RNA (internal standard) expression across all treatment groups indicate equal RNA loading and RNA quality.

mirna mediated knockdown

RNAi Knockdown Animal Models

With its ability to silence almost any gene, RNA interference (RNAi) is an invaluable tool for identifying and validating potential drug targets in vivo.

  • Silence difficult knockout targets.
  • Simultaneously knockdown two genes.
  • Mimic the action of antagonistic drugs.

In the absence of an RNAi inducer (doxycycline), the tet-repressor protein binds to the tet-operator control element and effectively inhibits the expression of short hairpin RNA (shRNA) from the H1 promoter.

When doxycycline is administered through an animal's feed or drinking water, it binds to the tet-repressor protein and blocks its interaction with the H1 promoter. This is followed by H1 promoter activation, shRNA expression, and effective RNA-mediated gene knockdown.

Withdrawal of doxycycline inhibits shRNA expression, resulting in pre-knockdown levels of target gene expression.

Overview of the Taconic ESC-mediated Gene Knock-in Workflow

The absence of suitable rat ES cells makes rat gene targeting studies highly challenging. Through the use of transgenic technology, however, Taconic is pleased to offer inducible RNAi rat models.

Pronuclear injection methodology has enabled Taconic scientists to microinject an inducible/reversible shRNA construct into the pronucleus of rat embryos. Following microinjection, embryos are transferred into pseudopregnant female rats. Resultant pups are then screened for the presence of the shRNA expression transgene.

As with RNAi knockdown mice, expression of the shRNA in transgenic rats is induced by the administration of doxycycline in food or water. Withdrawal of the inducer enables inhibition of shRNA expression.

inductable rnai rat

Double Gene Knockdowns

  • Study the genetic interaction of two targets by knocking down two genes at the same time.
  • Express two different shRNAs that recognize the same mRNA molecule in genes that are difficult to knockdown with a single shRNA.
  • Target a disease-causing mutation in one allele while leaving the normal allele intact.
double shrna knock down chain
reporter fluc graphs
double reporter gene

Cohort Production Package

  • Documentation and verification of PCR-based genotype protocol by Taconic Molecular Analysis.
  • Coordinated transfer of donor males to Taconic's breeding facility in Germantown, NY.
  • Confirmation of genotype of donor males by PCR-based genotyping.
  • RapidEXPANSION™ using C57BL/6NTac donor females.
  • Holding of excess donor males until offspring from RapidEXPANSION™ are weaned.
  • Initial post-rederivation comprehensive health testing (IHMS™-52).
  • PCR based genotyping of derived offspring.
  • Holding of derived pups from weaning until ready for shipment (4 weeks) at the Isolator Breeding Solutions facility.
  • Initial cohort of animals ready for shipment beginning at 5 weeks of age.
    • Large package 18-20/sex/genotype
    • Small package 8-10/sex/genotype
    • Genotypes include heterozygous and wild type
  • Package ends when initial cohort is ready for shipping. Post package breeding and fees will be based on your breeding plan.
  • Package includes initial health testing only; ongoing health testing can be done for an additional charge.
  • Shipping charges from Taconic to customer are not included in package.
  • Package assumes receipt of 4 donor males from Taconic, additional services will be charged at catalog prices.
  • Pricing assumes genetic modification is not sex linked, Mendelian ratios will be obtained, 80% of female breeders will deliver live pups that survive until weaning, and an average litter size of 5 pups. Additional charges may apply if these conditions are not met.
validation graph

Knockdown Mice

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Experience & Expertise You Can Trust

Taconic Biosciences' model generation team has produced about 5,000 models in the last 15 years, developing a globally-recognized reputation for advancing the work of in vivo researchers. Our scientific program managers are here to help you navigate the complexities of model generation.

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Featured Resources

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miRNA Publications:

Gebeshuber CA, Kornauth C, Dong L, Sierig R, Seibler J, Reiss M, Tauber S, Bilban M, Wang S, Kain R, Böhmig GA, Moeller MJ, Gröne HJ, Englert C, Martinez J, Kerjaschki D. (2013) Focal segmental glomerulosclerosis is induced by microRNA-193a and its downregulation of WT1. Nat Med. 19(4):481-7.

Jordan SD, Krüger M, Willmes DM, Redemann N, Wunderlich FT, Brönneke HS, Merkwirth C, Kashkar H, Olkkonen VM, Böttger T, Braun T, Seibler J, Brüning JC. (2011) Obesity-induced overexpression of miRNA-143 inhibits insulin-stimulated AKT activation and impairs glucose metabolism. Nat Cell Biol. 13(4):434-46.

Kornfeld JW, Baitzel C, Könner AC, Nicholls HT, Vogt MC, Herrmanns K, Scheja L, Haumaitre C, Wolf AM, Knippschild U, Seibler J, Cereghini S, Heeren J, Stoffel M, Brüning JC. (2013) Obesity-induced overexpression of miR-802 impairs glucose metabolism through silencing of Hnf1b. Nature. 494(7435):111-5.

RNAi Publications:

Gerrits H, Paradé MC, Koonen-Reemst AM, Bakker NE, Timmer-Hellings L, Sollewijn Gelpke MD, Gossen JA. (2014) Reversible infertility in a liver receptor homologue-1 (LRH-1)-knockdown mouse model. Reprod Fertil Dev. 26(2):293-306.

Michalak EM, Nacerddine K, Pietersen A, Beuger V, Pawlitzky I, Cornelissen-Steijger P, Wientjens E, Tanger E, Seibler J, van Lohuizen M, Jonkers J. (2013) Polycomb group gene Ezh2 regulates mammary gland morphogenesis and maintains the luminal progenitor pool. Stem Cells. 31(9):1910-20.

Vink PM, Smout WM, Driessen-Engels LJ, de Bruin AM, Delsing D, Krajnc-Franken MA, Jansen AJ, Rovers EF, van Puijenbroek AA, Kaptein A, Nolte MA, Garritsen A, van Eenennaam H. (2013) In vivo knockdown of TAK1 accelerates bone marrow proliferation/differentiation and induces systemic inflammation. PLoS One. 8(3):e57348.

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