Nanog co-regulated by Nodal/Smad2 and Oct4 is required for pluripotency in developing mouse epiblast

AbstractNanog, a core pluripotency factor, is required for stabilizing pluripotency of inner cell mass (ICM) and embryonic stem cells (ESCs), and survival of primordial germ cells in mice. Here, we have addressed function and regulation of Nanog in epiblasts of postimplantation mouse embryos by conditional knockdown (KD), chromatin immunoprecipitation (ChIP) using in vivo epiblasts, and protein interaction with the Nanog promoter in vitro. Differentiation of Nanog-KD epiblasts demonstrated requirement for Nanog in stabilization of pluripotency. Nanog expression in epiblast is directly regulated by Nodal/Smad2 pathway in a visceral endoderm-dependent manner. Notably, Nanog promoters switch from Oct4/Esrrb in ICM/ESCs to Oct4/Smad2 in epiblasts. Smad2 directly associates with Oct4 to form Nanog promoting protein complex. Collectively, these data demonstrate that Nanog plays a key role in stabilizing Epiblast pluripotency mediated by Nodal/Smad2 signaling, which is involved in Nanog promoter switching in early developing embryos

Cure of ADPKD by Selection for Spontaneous Genetic Repair Events in Pkd1-Mutated iPS Cells

Induced pluripotent stem cells (iPSCs) generated by epigenetic reprogramming of personal somatic cells have limited therapeutic capacity for patients suffering from genetic disorders. Here we demonstrate restoration of a genomic mutation heterozygous for Pkd1 (polycystic kidney disease 1) deletion (Pkd1(+/−) to Pkd1(+/R+)) by spontaneous mitotic recombination. Notably, recombination between homologous chromosomes occurred at a frequency of 1∼2 per 10,000 iPSCs. Southern blot hybridization and genomic PCR analyses demonstrated that the genotype of the mutation-restored iPSCs was indistinguishable from that of the wild-type cells. Importantly, the frequency of cyst generation in kidneys of adult chimeric mice containing Pkd1(+/R+) iPSCs was significantly lower than that of adult chimeric mice with parental Pkd1(+/−) iPSCs, and indistinguishable from that of wild-type mice. This repair step could be directly incorporated into iPSC development programmes prior to cell transplantation, offering an invaluable step forward for patients carrying a wide range of genetic disorders