In summary, we have constructed a miRNA tool kit as a solid basis for future teams to conduct engineering work based on the powerful technology of RNA interference. This includes on the one hand the new measurement standard miMeasure, which enabled us to measure miRNA abundance levels and in this way to realize tissue specific knockdown. On the other hand we developed the synthetic miRNA expression kit miTuner, which we used to measure a variety of miRNA binding sites to learn about the quantitative structure-activity relationship in living cells. This data enabled us further to develop a model, which improves our scientific understanding of the nature of miRNA regulation and allows a rational design of our tuning constructs. The rationally designed miTuner constructs could be successfully validated in cultured, transformed or primary liver cells and a transfer into an adult mouse model showed also positive results. We think that the introduction of this miRNA technology independently and in combination with the AAV system will pave the way for future iGEM teams to utilize the precise, predictable and quantitative adjustment of mammalian gene expression levels, and we further think that our work will foster the introduction of synthetic biology based technologies into the rapidly emerging field of especially personalized biomedicine.
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