title: A virus-free poly-promoter vector induces pluripotency in quiescent bovine cells under chemically defined conditions of dual kinase inhibition.
abstract: Authentic induced pluripotent stem cells (iPSCs), capable of giving rise to all cell types of an adult animal, are currently only available in mouse. Here, we report the first generation of bovine iPSC-like cells following transfection with a novel virus-free poly-promoter vector. This vector contains the bovine cDNAs for OCT4, SOX2, KLF4 and c-MYC, each controlled by its own independent promoter. Bovine fibroblasts were cultured without feeders in a chemically defined medium containing leukaemia inhibitory factor (LIF) and inhibitors of MEK1/2 and glycogen synthase kinase-3 signaling ('2i'). Non-invasive real-time kinetic profiling revealed a different response of bovine vs human and mouse cells to culture in 2i/LIF. In bovine, 2i was necessary and sufficient to induce the appearance of tightly packed alkaline phosphatase-positive iPSC-like colonies. These colonies formed in the absence of DNA synthesis and did not expand after passaging. Following transfection, non-proliferative primary colonies expressed discriminatory markers of pluripotency, including endogenous iPSC factors, CDH1, DPPA3, NANOG, SOCS3, ZFP42, telomerase activity, Tra-1-60/81 and SSEA-3/4, but not SSEA-1. This indicates that they had initiated a self-sustaining pluripotency programme. Bovine iPSC-like cells maintained a normal karyotype and differentiated into derivatives of all three germ layers in vitro and in teratomas. Our study demonstrates that conversion into induced pluripotency can occur in quiescent cells, following a previously undescribed route of direct cell reprogramming. This identifies a major species-specific barrier for generating iPSCs and provides a chemically defined screening platform for factors that induce proliferation and maintain pluripotency of embryo-derived pluripotent stem cells in livestock.
authors.affiliation: AgResearch, Ruakura Research Centre, Hamilton, New Zealand.
authors.forename: Ben
authors.initials: B
authors.lastname: Huang
authors.forename: Tong
authors.initials: T
authors.lastname: Li
authors.forename: Lucia
authors.initials: L
authors.lastname: Alonso-Gonzalez
authors.forename: Ruben
authors.initials: R
authors.lastname: Gorre
authors.forename: Sarah
authors.initials: S
authors.lastname: Keatley
authors.forename: Andria
authors.initials: A
authors.lastname: Green
authors.forename: Pavla
authors.initials: P
authors.lastname: Turner
authors.forename: Prasanna Kumar
authors.initials: PK
authors.lastname: Kallingappa
authors.forename: Vinod
authors.initials: V
authors.lastname: Verma
authors.forename: Björn
authors.initials: B
authors.lastname: Oback
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D005260:Female; D005822:Genetic Vectors / Q000235:genetics*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D000090062:Kruppel-Like Factor 4; D053605:Leukemia Inhibitory Factor / Q000494:pharmacology; D008297:Male; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D013724:Teratoma / Q000378:metabolism / Q000473:pathology
chemical_list: D015415:Biomarkers; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D053605:Leukemia Inhibitory Factor; D047428:Protein Kinase Inhibitors