Genetic engineering of human ES and iPS cells using TALE nucleases

Targeted genetic engineering of human pluripotent cells is a prerequisite for exploiting their full potential. Such genetic manipulations can be achieved using site-specific nucleases. Here we engineered transcription activator–like effector nucleases (TALENs) for five distinct genomic loci. At all loci tested we obtained human embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) clones carrying transgenic cassettes solely at the TALEN-specified location. Our data suggest that TALENs employing the specific architectures described here mediate site-specific genome modification in human pluripotent cells with similar efficiency and precision as do zinc-finger nucleases (ZFNs).National Institutes of Health (U.S.) (Grant R37-CA084198)National Institutes of Health (U.S.) (Grant RO1-CA087869)National Institutes of Health (U.S.) (Grant RO1-HD045022)Howard Hughes Medical Institut

Co-targeting among microRNAs is widespread and enriched in the brain

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2019Cataloged from PDF version of thesis. Vita.Includes bibliographical references.MicroRNAs (miRNAs) play roles in diverse developmental processes and cellular differentiation. Distinct miRNAs have hundreds to thousands of conserved binding sites in mRNAs, but typically exert only modest repression on a single site. Co-targeting of individual mRNAs by multiple different miRNAs could be commonly used to achieve stronger and more complex patterns of repression. Comparing target sets of different miRNAs, we identified hundreds of pairs of miRNAs that share more mRNA targets than expected (often ~2-fold or more) relative to stringent controls. For one co-targeting pair, miR-138 and miR-137, we validated functional overlap in neuronal differentiation. Clustering of the pairing relationships revealed a group of 9 predominantly brain-enriched miRNAs that share many targets. In reporter assays, subsets of these miRNAs together repressed gene expression by 5- to 10-fold or more, sometimes exhibiting cooperative repression. Our results uncover an unexpected pattern in which certain combinations of miRNAs can collaborate to strongly repress particular targets, and suggest important developmental roles.by Jennifer M. Cherone.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Biolog