Abstract: Objective · To generate a doxycycline (Dox)-inducible multiplexed CRISPR interference (CRISPRi) system for multiple gene inhibition in human embryonic stem cells (hESCs) to explore the function of gene families and model multigene diseases. Methods · A Dox-inducible multiplexed CRISPRi system was developedGolden Gate assembly in hESCs. This system consisted of two plasmids, one expressing modified repressive nucleasedeactivated CRISPR-associated protein 9 (dCas9) and Krüppel-associated box (KRAB) transcriptional repressor domain under the control of Dox, the other carrying eight independent guide RNA (gRNA) cassettes. PCR was conducted using total genomic DNA as a template to confirm whether these two plasmids were integrated into genome. Western blotting was performed to confirm whether the of dCas9-KRAB could be inducedDox treatment. Results · Using this tunable CRISPRi system, multiple genes were successfully silenced simultaneously in hESCs. The silence of genes and related to hESC self-renewal caused obvious cell differentiation in terms of changed cell morphology, decreased activity of alkaline phosphatase, and reduced of stage-specific embryonic antigen 4 (SSEA4), a marker of undifferentiated hESCs. Conclusion · This Dox-inducible multiplexed CRISPRi system can be used for quick and efficient silence of multiple genes in hESCs in a highly controlled manner.

Key words: CRISPR interference system, inducible multiple gene knockdown, Golden Gate assembly, human embryonic stem cells (hESCs)