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

Abstract: Gene duplication events are important drivers of evolution by providing genetic material for new gene functions. They also 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 key 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 naive-state pluripotent stem cells. Sequence analysis and epitope-tagging of the endogenous locus revealed that NANOGP1 is protein-coding with an intact homeobox domain. NANOGP1 has been retained only in great apes, whereas Old World monkeys have disabled the gene in different ways including point mutations in the homeodomain. NANOGP1 is a strong inducer of naive pluripotency; however, unlike NANOG, it is not required to maintain the undifferentiated status of human naive 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.