Combining a tetracycline (Tet)-inducible gRNA system and CRISPRa for titratable and timely controlled enhancement of endogenous SHISA3 activation in human induced pluripotent stem cells (hiPSC).

Towards increasing the possibility for temporal control of gene expression using CRISPR activation (a) systems, we generated homozygous human induced pluripotent stem cell (hiPSC) lines carrying a doxycycline (dox)-inducible guide(g)-RNA construct targeting the SHISA3 transciptional start site, as proof-of-principle, or a non targeting gRNA as a control. The dox-inducible gRNA cassette was inserted into the human ROSA26 locus in a line with dCas9VPR integrated at the AAVS1 locus (CRISPRa/Tet-iSHISA3). Pluripotency, genomic integrity and differentiation potential into all three germ layers were maintained. Dox-dependent gene induction was validated in hiPSCs as well as derived fibroblasts. These lines provide an attractive tool for cellular reprogramming in hiPSC-derived cells in a timely controlled manner.