Phosphorylation of NANOG by casein kinase I regulates embryonic stem cell self-renewal

Micelle-like clusters in phase-separated Nanog condensates: A molecular simulation study

The phase separation model for transcription suggests that transcription factors (TFs), coactivators, and RNA polymerases form biomolecular condensates around active gene loci and regulate transcription. However, the structural details of condensates remain elusive. In this study, for Nanog, a master TF in mammalian embryonic stem cells known to form protein condensates in vitro, we examined protein structures in the condensates using residue-level coarse-grained molecular simulations. Human Nanog formed micelle-like clusters in the condensate. In the micelle-like cluster, the C-terminal disordered domains, including the tryptophan repeat (WR) regions, interacted with each other near the cluster center primarily via hydrophobic interaction. In contrast, hydrophilic disordered N-terminal and DNA-binding domains were exposed on the surface of the clusters. Electrostatic attractions of these surface residues were responsible for bridging multiple micelle-like structures in the condensate. The micelle-like structure and condensate were dynamic and liquid-like. Mutation of tryptophan residues in the WR region which was implicated to be important for a Nanog function resulted in dissolution of the Nanog condensate. Finally, to examine the impact of Nanog cluster to DNA, we added DNA fragments to the Nanog condensate. Nanog DNA-binding domains exposed to the surface of the micelle-like cluster could recruit more than one DNA fragments, making DNA-DNA distance shorter.

Culture of leukocyte-derived cells from human peripheral blood: Increased expression of pluripotent genes OCT4, NANOG, SOX2, self-renewal gene TERT and plasticity

There are few stem cells in human peripheral blood (PB). Increasing the population and plasticity of stem cells in PB and applying it to regenerative medicine require suitable culture methods. In this study, leukocyte populations 250 mL of PB were collected using a blood separator before that were cultured in optimal cell culture medium for 4 to 7 days. After culturing, stemness characteristics were analyzed, and red blood cells were removed from the cultured cells. In our results, stemness markers of the leukocyte populations Sca-1+ CD45+, CD117+ CD45+, and very small embryonic-like stem cells CD34+ Lin- CD45- and CXCR4+ Lin- CD45- were significantly increased. Furthermore, the expression of stem cell genes OCT4 (POU5F1), NANOG, SOX2, and the self-renewal gene TERT was analyzed by quantitative real-time polymerase chain reaction in these cells, and it showed a significant increase. These cells could be candidates for multi-potential cells and were further induced using trans-differentiation culture methods. These cells showed multiple differentiation potentials for osteocytes, nerve cells, cardiomyocytes, and hepatocytes. These results indicate that appropriate culture methods can be applied to increase expression of pluripotent genes and plasticity. Leukocytes of human PB can be induced to trans-differentiate into pluripotent potential cells, which will be an important breakthrough in regenerative medicine.

NANOGP1, a tandem duplicate of NANOG, exhibits partial functional conservation in human naïve pluripotent stem cells

Gene duplication events can drive evolution by providing genetic material for new gene functions, and they create opportunities for diverse developmental strategies to emerge between species. To study the contribution of duplicated genes to human early development, we examined the evolution and function of NANOGP1, a tandem duplicate of the transcription factor NANOG. We found that NANOGP1 and NANOG have overlapping but distinct expression profiles, with high NANOGP1 expression restricted to early epiblast cells and naïve-state pluripotent stem cells. Sequence analysis and epitope-tagging revealed that NANOGP1 is protein coding with an intact homeobox domain. The duplication that created NANOGP1 occurred earlier in primate evolution than previously thought and has been retained only in great apes, whereas Old World monkeys have disabled the gene in different ways, including homeodomain point mutations. NANOGP1 is a strong inducer of naïve pluripotency; however, unlike NANOG, it is not required to maintain the undifferentiated status of human naïve pluripotent cells. By retaining expression, sequence and partial functional conservation with its ancestral copy, NANOGP1 exemplifies how gene duplication and subfunctionalisation can contribute to transcription factor activity in human pluripotency and development.

Characterization of nanog in Nile tilapia (Oreochromis niloticus) and its spatiotemporal expression patterns during embryonic and gonadal development

Nanog is one of the well-characterized core transcription factors in pluripotency maintenance network. So far, studies on fishes indicate that the Nanog expression occurs from embryonic 1-cell stage to blastula stage, and is restricted to the gonadal germline cells in adult tissues, which is strikingly different from that in mammals. However, whether this expression profile is conservative in fishes remains to be investigated. Here Nile tilapia (Oreochromis niloticus) nanog (named as Ong) was identified and its spatiotemporal expression patterns during embryonic and gonadal development were investigated. The Ong cDNA contains an open reading frame of 678 bp, encoding 226 amino acids. The anti-Ong antibody was prepared through prokaryotic protein expression and its specificity was validated. The Ong expression in embryonic 1-cell stage did not appear until the early stage of blastocyst and continued to the late stage of blastocyst. In adult tissues, its expression was limited to gonads. Its expression patterns during gonadal development were further investigated by in situ hybridization and immunohistochemical staining. In testis, Ong was not expressed at 30 dah (days after hatching), but highly expressed in spermatogonia and spermatocytes at 150 dah; in ovaries at 30 and 150 dah, it was not expressed in germline cells but in all somatic cells. This expression profile is strikingly different from reports in fishes to date. Our study firstly indicates that the Nanog expression profile is not conservative in fishes. This study is valuable for further functional and evolutionary study of this gene.

The multiple faces of NANOG in cancer: a therapeutic target to chemosensitize therapy-resistant cancers

The transcription factor NANOG regulates self-renewal and pluripotency in embryonic cells, and its downregulation leads to cell differentiation. Recent studies have linked upregulation of NANOG in various cancers and the regulation of expression of different molecules, and vice versa, to induce proliferation, metastasis, invasion and chemoresistance. Thus NANOG is an oncogene that functions by inducing stem cells' circuitries and heterogeneity in cancers. Understanding NANOG's role in various cancers may lead to it becoming a therapeutic target to halt cancer progression. The NANOG network can also be targeted to resensitize resistant cancer cells to conventional therapies. The current review focuses on NANOG regulation in the various signaling networks leading to cancer progression and chemoresistance, and highlights the therapeutic aspect of targeting NANOG in various cancers.