Engineered endosymbionts capable of directing mammalian cell gene expression

Modular methods for directing mammalian gene expression would enable advances in tissue regeneration, enhance cell-based therapeutics and improve modulation of immune responses. To address this challenge, engineered endosymbionts (EES) that escape endosomal destruction, reside in the cytoplasm of mammalian cells, and secrete proteins that are transported to the nucleus to control host cell gene expression were developed. Microscopy confirmed that EES escape phagosomes, replicate within the cytoplasm, and can secrete reporter proteins into the cytoplasm that were then transported to the nucleus. Synthetic operons encoding the mammalian transcription factors, Stat-1 and Klf6 or Klf4 and Gata-3 were recombined into the EES genome. Using controlled induction, these EES were shown to direct gene expression in J774A.1 macrophage/monocyte cells and modulate the host cell fates. Expressing mammalian transcription factors from engineered intracellular bacteria as endosymbionts comprises a new tool for directing host cell gene expression for therapeutic and research purposes. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=194 SRC="FIGDIR/small/463266v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@2b5935org.highwire.dtl.DTLVardef@1edd8edorg.highwire.dtl.DTLVardef@3cb5b9org.highwire.dtl.DTLVardef@1be9b5f_HPS_FORMAT_FIGEXP M_FIG C_FIG