Functional microRNA Profiling for Improved iPSC Reprogramming
Conference Recording Jan 20, 2013
About the Speaker
Jan Fiedler is a Post Doctoral Researcher at the Institute of Molecular and Translational Therapeutic Strategies (IMTTS) at Hannover Medical School. His main focus of research is investigating basic signalling mechanisms of cardiac remodelling and its different mediators. Studying the role of microRNAs during myocardial infarction. Besides the role of microRNAs in translational cardiovascular research, Jan Fiedler also investigates the potential of microRNAs for somatic cell reproramming offering an opportunity to generate different cardiovascular cells.
Defined expression of the transcription factors Oct4, Sox2 and Klf4 has been used to reprogram adult fibroblast cells to induced pluripotent stem cells (iPS cells). Based on their nature, iPS cells can be an important source for regenerative medicine in cardiovascular disease by their potential to differentiate into various cardiovascular cell types. In addition to transcription factors, microRNAs (miRs, miRNAs) can regulate transcript expression either by mRNA degradation or suppression of translation and thus can directly influence genomic rearrangements and cell fate. We transfected a murine miRNA library to murine embryonic fibroblasts (MEFs) derived from Oct4:GFP transgenic mice for their ability to support reprogramming and iPS cell generation. Initially, MEFs were transduced with a polycistronic Oct4-Sox2-Klf4 retrovector. 24 h later, miRNAs (50 nM) from the miRNA library (379 miRNAs) and respective controls were transfected. At day 7 to 10 iPS colonies were counted. We set a threshold of 4-fold induction related to control level and could identify a set of miRNAs critically regulating iPS formation. We identified a miRNA family targeting the transcription factor Meox2, which was confirmed by Western Blot and luciferase 3´-UTR reporter analyses. In line, mimicking Meox2 repression by a specific siRNA also elevated the number of iPS cells during reprogramming. In conclusion, we report the ability of miRNAs to support reprogramming in MEFs via Meox2 repression. Use of miRNAs to support iPS cell generation will be helpful for future regenerative therapies.