An Optogenetic‐Controlled Cell Reprogramming System for Driving Cell Fate and Light‐Responsive Chimeric Mice

Abstract Pluripotent stem cells (PSCs) hold great promise for cell‐based therapies, disease modeling, and drug discovery. Classic somatic cell reprogramming to generate induced pluripotent stem cells (iPSCs) is often achieved based on overexpression of transcription factors (TFs). However, this process is limited by side effect of overexpressed TFs and unpredicted targeting of TFs. Pinpoint control over endogenous TFs expression can provide the ability to reprogram cell fate and tissue function. Here, a light‐inducible cell reprogramming (LIRE) system is developed based on a photoreceptor protein cryptochrome system and clustered regularly interspaced short palindromic repeats/nuclease‐deficient CRISPR‐associated protein 9 for induced PSCs reprogramming. This system enables remote, non‐invasive optogenetical regulation of endogenous Sox2 and Oct4 loci to reprogram mouse embryonic fibroblasts into iPSCs (iPSC_LIRE) under light‐emitting diode‐based illumination. iPSC_LIRE cells can be efficiently differentiated into different cells by upregulating a corresponding TF. iPSC_LIRE cells are used for blastocyst injection and optogenetic chimeric mice are successfully generated, which enables non‐invasive control of user‐defined endogenous genes in vivo, providing a valuable tool for facile and traceless controlled gene expression studies and genetic screens in mice. This LIRE system offers a remote, traceless, and non‐invasive approach for cellular reprogramming and modeling of complex human diseases in basic biological research and regenerative medicine applications.