Generation of a Drug-inducible Reporter System to Study Cell Reprogramming in Human Cells*

Strategies on the basis of doxycycline-inducible lentiviruses in mouse cells allowed the examination of mechanisms governing somatic cell reprogramming.Using a doxycycline-inducible human reprogramming system, we identified unreported miRs enhancing reprogramming efficiency.We generated a drug-inducible human reprogramming reporter system as an invaluable tool for genetic or chemical screenings.These cellular systems provide a tool to enable the advancement of reprogramming technologies in human cells. Reprogramming of somatic cells into induced pluripotent stem cells is achieved by the expression of defined transcription factors. In the last few years, reprogramming strategies on the basis of doxycycline-inducible lentiviruses in mouse cells became highly powerful for screening purposes when the expression of a GFP gene, driven by the reactivation of endogenous stem cell specific promoters, was used as a reprogramming reporter signal. However, similar reporter systems in human cells have not been generated. Here, we describe the derivation of drug-inducible human fibroblast-like cell lines that express different subsets of reprogramming factors containing a GFP gene under the expression of the endogenous OCT4 promoter. These cell lines can be used to screen functional substitutes for reprogramming factors or modifiers of reprogramming efficiency. As a proof of principle of this system, we performed a screening of a library of pluripotent-enriched microRNAs and identified hsa-miR-519a as a novel inducer of reprogramming efficiency.