miBricks: DNA is not enough
The iGEM Team Heidelberg 2010 unlocks the entirely new field of synthetic mi(cro)RNA technologies for mammalian cells and tissue engineering. By combining novel miRNA-based tools and protocols with cell-specific viral delivery systems our technology allows - for the first time - to use RNAi for rationally engineering gene regulation in targeted cells and organs. The two most prominent technologies we developed are a new measurement standard for real-time detection/quantification of miRNA binding site strength in living cells (miMeasure) as well as a synthetic miRNA expression kit (miTuner) that allows to precisely repress (fully or partly) and thus fine-regulate any desired target gene. The rational design of this miRNA expression kit is accomplished by a novel computational model for miRNA-based gene silencing termed miBEAT. The miRNA technology is accompanied by a novel gene delivery technology based on re-designed Adeno-associated viruses (AAV) that were molecularly engineered and evolved to specifically deliver our miRNA expression kit to hepatocytes. The rationally designed synthetic miRNA expression kits were successfully validated in cultured, transformed or primary liver cells and then transferred into an adult mouse model. We thereby demonstrate that our miRNA expression kit is able to specifically fine tune the expression level of target genes both in cell culture (in vitro) and importantly also in the liver of mice (in vivo). In summary, we show that this technology allows the precise, predictable and quantitative adjustment of mammalian gene expression levels. Our work fosters the introduction of synthetic biology based technologies into the rapidly emerging field of personalized biomedicine.