Recombinant microRNAs in xenobiotic metabolism and disposition

PROJECT SUMMARY Understanding the molecular mechanisms behind variable drug metabolism and disposition (DMD) is critical to improve pharmacotherapy and drug development. The ultimate goal of my research is to decipher novel posttranscriptional regulation mechanisms controlled by noncoding microRNAs (miRNAs) and establish their importance in DMD. My laboratory pioneered miRNA research in the fields of DMD that is expected to fill the critical gaps in understanding new posttranscriptional regulation mechanisms. Nevertheless, current studies on miRNA functions in DMD, as well as in the broad areas of general medical sciences, are limited to the use of chemo-engineered RNA “mimics” made in vitro, which, comprised of extensive and various types of chemical modifications, are fundamentally different from natural RNA molecules that are produced and folded in cells and do not carry or just have minimal degree of posttranscriptional modifications. This is also in sharp contrast to protein research that has found the ultimate success by using recombinant or bioengineered proteins produced and folded in living cells, instead of synthetic polypeptides or proteins made in vitro. Very recently, we have developed a novel recombinant RNA technology, based upon hybrid tRNA/pre-miRNA carriers, which offers high-yield and large-scale production of recombinant miRNA agents (& small interfering RNAs or siRNAs) through cost-effective bacterial fermentation. Our studies have also demonstrated that bioengineered miRNA agent (BERA) acts as a “prodrug”, which is specifically processed to target miRNA molecule in human cells to selectively regulate target gene expression. Further, the access to large quantity (tens milligrams from 1 L bacterial culture) of high-purity (>98%) recombinant miRNA molecules allows us to readily investigate the impact of miRNAs on pharmacokinetics and pharmacodynamics (PK/PD) in animal models in vivo. These highly innovative approaches and one-of-its-kind recombinant miRNA tools shall open up new avenues for miRNA research and development, as well as broadly general medical sciences. In this MIRA application, we propose to produce and utilize one-of-a-kind recombinant miRNAs to dissect new regulatory mechanisms in DMD by addressing the following key questions: 1) Can the tRNA/pre-miRNA-based technology be re-innovated for the production of fully-humanized recombinant miRNAs (hBERA/miRNAs)? 2) Will hBERA/miRNAs be processed to target miRNAs in human hepatocytes and liver cells to selectively modulate drug-metabolizing enzyme or transporter expression, and alter cellular DMD capacity? 3) To what degrees will miRNA alter PK and PD in the whole-body system?