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Approaches:
 PRISMWould you like to turn your conventional KO into an inducible mutant? Just use PRISM!
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 PRISM: inducible method
PRISM refers to a new approach that we developed called Pharmacological Regulated Induction of Mutations. A limitation of traditional KO approaches has been that the mutations are present from birth, and therefore it is often difficult to determine when they affect learning and memory. To circumvent this limitation, we have used a number of strategies including one that takes advantage of synergistic interactions between pharmacology and genetics.
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A simple strategy to turn classical KOs into inducible tools
The idea is to use drugs to reveal genetic phenotypes. The important aspect of this approach is that neither the genetic nor the pharmacological manipulation alone result in measurable deficits. Only the combination of the two manipulations (genetic and pharmacological) reveal the phenotype of interest. For example, drugs that block NMDA receptors impair learning (i.e., CPP). However, low concentrations of these drugs do not affect learning in normal mice. Additionally, the genetic replacement of threonine for alanine at position 286 in the alpha calmodulin kinase II (CaMKII) blocks learning. Nevertheless, learning is unchanged in a-CaMKIIT286A heterozygotes, since in these mice only half of the normal complement of the protein has been mutated. Strikingly, low levels of NMDA receptor blockers impair LTP and learning in these heterozygous mutants, but not in their normal littermates. We have obtained similar synergistic interactions between MEK inhibitors and a K-ras heterozygous null mutation. PRISM is very powerful because it allows us to control WHEN the phenotypes are revealed. This inducibility is critical for the design of many experiments and it helps to address concerns that the mutations affected unintended processes, such as development. For more information see (PDF)
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