title: Retinoic Acid Inducible Gene 1 Protein (RIG1)-Like Receptor Pathway Is Required for Efficient Nuclear Reprogramming.
abstract: We have revealed a critical role for innate immune signaling in nuclear reprogramming to pluripotency, and in the nuclear reprogramming required for somatic cell transdifferentiation. Activation of innate immune signaling causes global changes in the expression and activity of epigenetic modifiers to promote epigenetic plasticity. In our previous articles, we focused on the role of toll-like receptor 3 (TLR3) in this signaling pathway. Here, we define the role of another innate immunity pathway known to participate in response to viral RNA, the retinoic acid-inducible gene 1 receptor (RIG-1)-like receptor (RLR) pathway. This pathway is represented by the sensors of viral RNA, RIG-1, LGP2, and melanoma differentiation-associated protein 5 (MDA5). We first found that TLR3 deficiency only causes a partial inhibition of nuclear reprogramming to pluripotency in mouse tail-tip fibroblasts, which motivated us to determine the contribution of RLR. We found that knockdown of interferon beta promoter stimulator 1, the common adaptor protein for the RLR family, substantially reduced nuclear reprogramming induced by retroviral or by modified messenger RNA expression of Oct 4, Sox2, KLF4, and c-MYC (OSKM). Importantly, a double knockdown of both RLR and TLR3 pathway led to a further decrease in induced pluripotent stem cell (iPSC) colonies suggesting an additive effect of both these pathways on nuclear reprogramming. Furthermore, in murine embryonic fibroblasts expressing a doxycycline (dox)-inducible cassette of the genes encoding OSKM, an RLR agonist increased the yield of iPSCs. Similarly, the RLR agonist enhanced nuclear reprogramming by cell permeant peptides of the Yamanaka factors. Finally, in the dox-inducible system, RLR activation promotes activating histone marks in the promoter region of pluripotency genes. To conclude, innate immune signaling mediated by RLR plays a critical role in nuclear reprogramming. Manipulation of innate immune signaling may facilitate nuclear reprogramming to achieve pluripotency. Stem Cells 2017;35:1197-1207.
authors.affiliation: Division of Cardiovascular Medicine, Stanford University, Stanford, California, 94305, USA.
authors.forename: Nazish
authors.initials: N
authors.lastname: Sayed
authors.affiliation: Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, Texas, 77030, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Ospino
authors.affiliation: Division of Cardiovascular Medicine, Stanford University, Stanford, California, 94305, USA.
authors.forename: Farhan
authors.initials: F
authors.lastname: Himmati
authors.affiliation: Division of Cardiovascular Medicine, Stanford University, Stanford, California, 94305, USA.
authors.forename: Jieun
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, Texas, 77030, USA.
authors.forename: Palas
authors.initials: P
authors.lastname: Chanda
authors.affiliation: Department of Microbiology and Immunology, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia.
authors.forename: Edward S
authors.initials: ES
authors.lastname: Mocarski
authors.affiliation: Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, Texas, 77030, USA.
authors.forename: John P
authors.identifier: 0000-0003-0033-9138
authors.initials: JP
authors.lastname: Cooke
mesh_terms: D000818:Animals; D065150:Cellular Reprogramming / Q000187:drug effects / Q000235:genetics*; D000071457:DEAD Box Protein 58 / Q000378:metabolism*; D044127:Epigenesis, Genetic / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D000090062:Kruppel-Like Factor 4; D008024:Ligands; D018345:Mice, Knockout; D039904:Pluripotent Stem Cells / Q000187:drug effects / Q000378:metabolism; D012367:RNA, Viral / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015398:Signal Transduction; D013623:Tail; D051196:Toll-Like Receptor 3 / Q000378:metabolism
chemical_list: C551867:5'PPP-RNA; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D008024:Ligands; D012367:RNA, Viral; D011956:Receptors, Cell Surface; D051196:Toll-Like Receptor 3; C503356:Ddx58 protein, mouse; D000071457:DEAD Box Protein 58
keywords: Induced pluripotent stem cells; Pluripotency; Pluripotent stem cells; Reprogramming; Transdifferentiation