NANOG is a key factor for induction of pluripotency in bovine adult fibroblasts1

Since the first reports on isolation of pluripotent mouse embryonic stem (ES) cells 3 decades ago, there have been numerous attempts to derive ES cell lines from commercially important livestock species with limited success. The recent discovery that ectopic expression of a handful of stem cell-related genes was capable of inducing pluripotency in rodents and primates provided a novel approach to derivation of pluripotent stem cell lines. We used this approach in cattle and demonstrated that the ectopic expression of POU5F1 (also known as Oct4), SOX2, KLF4, and c-MYC alone was not sufficient for stable induction of pluripotency in bovine adult fibroblasts and that the additional expression of NANOG to the reprogramming cocktail was essential for the generation of stable bovine (b) induced pluripotent stem (iPS) cells. The resulting biPS cells were characterized by reverse-transcription PCR for a panel of ES marker genes. Immunocytochemical localization of POU5F1, SSEA-1, SSEA-4, and colorimetric alkaline phosphatase activity was measured in the iPS clones. The differentiation potential of the biPS cells was determined in vitro by expression of differentiation markers in embryoid bodies. Injection of biPS into immunocompromised mice resulted in teratomas containing cell types of the 3 germ lineages. This study reports the first generation of bovine induced pluripotent cell lines and paves the way for the use of biPS cells for biotechnological and agricultural purposes.