Nanog promotes transfer of pluripotency after cell fusion

Publisher Website
Google Scholar
Abstract
Fusion of cultured pluripotent embryonic stem cells with somatic cells is used to show that raising the levels of the transcription factor Nanog stimulates pluripotent gene activation from the somatic cell genome. Thus Nanog plays a dominant role in controlling pluripotent gene expression or chromatin remodeling. Through cell fusion, embryonic stem (ES) cells can erase the developmental programming of differentiated cell nuclei and impose pluripotency1,2. Molecules that mediate this conversion should be identifiable in ES cells. One candidate is the variant homeodomain protein Nanog, which has the capacity to entrain undifferentiated ES cell propagation3,4. Here we report that in fusions between ES cells and neural stem (NS) cells, increased levels of Nanog stimulate pluripotent gene activation from the somatic cell genome and enable an up to 200-fold increase in the recovery of hybrid colonies, all of which show ES cell characteristics. Nanog also improves hybrid yield when thymocytes or fibroblasts are fused to ES cells; however, fewer colonies are obtained than from ES × NS cell fusions, consistent with a hierarchical susceptibility to reprogramming among somatic cell types. Notably, for NS × ES cell fusions elevated Nanog enables primary hybrids to develop into ES cell colonies with identical frequency to homotypic ES × ES fusion products. This means that in hybrids, increased Nanog is sufficient for the NS cell epigenome to be reset completely to a state of pluripotency. We conclude that Nanog can orchestrate ES cell machinery to instate pluripotency with an efficiency of up to 100% depending on the differentiation status of the somatic cell.