NANOGP1, a tandem duplicate of NANOG, exhibits partial functional conservation in human naïve pluripotent stem cells
Ontology highlight
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 naïve-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 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.
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naïve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naïve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naïve pluripotent state, and subsequently undergo aberrant priming and early lineage commitment at the post-implantation stage. A comprehensive functional and genomic analysis involving profiling of m6A, RNA transcription and translation in Mettl3 wild-type and knockout pluripotent and differentiated cells, identified m6A as a critical determinant that destabilizes secondary naïve specific pluripotency genes Esrrb, Klf4 and Nanog, and restrains their transcript stability and translation efficiency. In summary, our findings provide for the first time evidence for a critical role for an mRNA epigenetic modification in early mammalian development in vivo, and identify a mechanism that functionally regulates mouse naïve and primed pluripotency in an opposing manner. Ribosome footprint (Ribo-Seq) was measured from mouse embryonic stem cells and mouse embriod bodies, in WT and Mettl3-KO cell lines.
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naïve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naïve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naïve pluripotent state, and subsequently undergo aberrant priming and early lineage commitment at the post-implantation stage. A comprehensive functional and genomic analysis involving profiling of m6A, RNA transcription and translation in Mettl3 wild-type and knockout pluripotent and differentiated cells, identified m6A as a critical determinant that destabilizes secondary naïve specific pluripotency genes Esrrb, Klf4 and Nanog, and restrains their transcript stability and translation efficiency. In summary, our findings provide for the first time evidence for a critical role for an mRNA epigenetic modification in early mammalian development in vivo, and identify a mechanism that functionally regulates mouse naïve and primed pluripotency in an opposing manner. polyA RNA-seq was measured in mouse embryonic stem cells (ESCs) and embroid bodies (EBs), each in WT and in Mettl3-KO cell lines. RNA-seq was measured also from WT mouse embronic fibroblasts (MEF). 3 biological replicates are available from ESCs and 2 from EBs. Replicate C in ESCs was measured alongside protein levels (SILAC) and was used for the analysis of that assay.
Project description:Pluripotency is highly dynamic and progresses through a continuum of pluripotent stem-cell states. The two states that bookend the pluripotency continuum, naïve and primed, are well characterized, but our understanding of the intermediate states and transitions between them remain incomplete. Here, we dissect the dynamics of pluripotent state transitions underlying pre- to post-implantation epiblast differentiation. Through comprehensive mapping of the proteome, phosphoproteome, transcriptome, and epigenome of embryonic stem cells transitioning from naïve to primed pluripotency, we find that rapid, acute, and widespread changes to the phosphoproteome precede ordered changes to the epigenome, transcriptome, and proteome. Reconstruction of kinase-substrate networks reveals signaling cascades, dynamics, and crosstalk. Distinct waves of global proteomic changes mark discrete phases of pluripotency, with cell state-specific surface markers tracking pluripotent state transitions. Our data provide new insights into the multi-layered control of the phased progression of pluripotency and a foundation for modeling mechanisms regulating pluripotent state transitions (www.stemcellatlasorg).
Project description:Small apes (family Hylobatidae), encompassing gibbons and siamangs, occupy a pivotal evolutionary position within the hominoid lineage, bridging the gap between great apes and catarrhine monkeys. Although they possess distinctive genomic and phenotypic features—such as rapid chromosomal rearrangements and adaptations for brachiation—functional genomic studies on small apes have been hindered by the limited availability of biological samples and developmental models. Here, we address this gap by successfully reprogramming primary skin fibroblasts from three small ape species: lar gibbons (Hylobates lar), Abbott’s gray gibbons (Hylobates abbotti), and siamangs (Symphalangus syndactylus). Using Sendai virus-based stealth RNA vectors, we generated 31 reprogrammed cell lines, five of which were developed into transgene-free induced pluripotent stem cells (iPSCs). These iPSCs displayed canonical features of primed pluripotency, both morphologically and molecularly, consistent with other primate iPSCs. Directed differentiation experiments confirmed the capacity of small ape iPSCs to generate cells representing all three germ layers. Particularly, the successful differentiation into limb bud mesoderm cells underscores their utility in investigating the molecular and developmental mechanisms unique to small ape forelimb evolution. Transcriptomic profiling of small ape iPSCs revealed significant upregulation of pluripotency-associated genes, alongside elevated expression of transposable elements. Remarkably, LAVA retrotransposons—a class of elements specific to small apes—exhibited particularly high expression levels in these cells. Comparative transcriptomic analyses with iPSCs from humans, great apes, and macaques identified evolutionary trends and clade-specific gene expression signatures. These signatures highlighted processes linked to genomic stability and cell death, providing insights into small ape-specific adaptations. This study positions small ape iPSCs as a transformative tool for advancing functional genomics and evolutionary developmental biology. By facilitating detailed investigations into hominoid genome evolution and phenotypic diversification, this system bridges critical gaps in comparative research, enabling deeper exploration of the genetic and cellular underpinnings of small ape-specific traits.
Project description:The pluripotency factor Oct4 is essential for the maintenance of naïve pluripotent stem cells in vitro and in vivo. However, the specific role of Oct4 in this process remains unknown. Here, we developed a rapid protein-level Oct4 depletion system that demonstrates that the immediate downstream response to loss of Oct4 is reduced expression of key pluripotency factors. Our data show a requirement for Oct4 for the efficient transcription of several key pluripotency factors, and suggest that expression of trophectoderm markers is a subsequent event. Additionally, we find that Nanog is competent to bind to the genome in the absence of Oct4, and this binding is in fact enhanced. Globally, however, active enhancer associated histone mark H3K27ac is depleted. Our work establishes that while Oct4 is required for the maintenance of the naïve transcription factor network, at a normal ESC level it antagonises this network through inhibition of Nanog binding
Project description:The pluripotency factor Oct4 is essential for the maintenance of naïve pluripotent stem cells in vitro and in vivo. However, the specific role of Oct4 in this process remains unknown. Here, we developed a rapid protein-level Oct4 depletion system that demonstrates that the immediate downstream response to loss of Oct4 is reduced expression of key pluripotency factors. Our data show a requirement for Oct4 for the efficient transcription of several key pluripotency factors, and suggest that expression of trophectoderm markers is a subsequent event. Additionally, we find that Nanog is competent to bind to the genome in the absence of Oct4, and this binding is in fact enhanced. Globally, however, active enhancer associated histone mark H3K27ac is depleted. Our work establishes that while Oct4 is required for the maintenance of the naïve transcription factor network, at a normal ESC level it antagonises this network through inhibition of Nanog binding
Project description:The pluripotency factor Oct4 is essential for the maintenance of naïve pluripotent stem cells in vitro and in vivo. However, the specific role of Oct4 in this process remains unknown. Here, we developed a rapid protein-level Oct4 depletion system that demonstrates that the immediate downstream response to loss of Oct4 is reduced expression of key pluripotency factors. Our data show a requirement for Oct4 for the efficient transcription of several key pluripotency factors, and suggest that expression of trophectoderm markers is a subsequent event. Additionally, we find that Nanog is competent to bind to the genome in the absence of Oct4, and this binding is in fact enhanced. Globally, however, active enhancer associated histone mark H3K27ac is depleted. Our work establishes that while Oct4 is required for the maintenance of the naïve transcription factor network, at a normal ESC level it antagonises this network through inhibition of Nanog binding
Project description:Nanog, a core pluripotency factor in the inner cell mass of blastocysts, is also expressed in unipotent primordial germ cells (PGC) in mice1, where its precise role is yet unclear2-4. We investigated this in an in vitro model, where naïve pluripotent embryonic stem cells (ESCs) cultured in bFGF/ActivinA develop as epiblast-like cells (EpiLCs), and gain competence for PGC-like fate5. Consequently, bone morphogenetic protein (BMP4), or ectopic expression of key germline transcription factors Prdm1/ Prdm14/ Tfap2c, directly induce PGC-like cells (PGCLCs) in EpiLCs, but not in ESCs6-8. Here we report an unexpected discovery that Nanog alone can induce PGCLCs in EpiLCs, independently of BMP4. We propose that following the dissolution of the naïve ESC pluripotency network during establishment of EpiLCs9,10, the epigenome is reset for cell fate determination. Indeed, we found genome-wide changes in NANOG binding pattern between ESCs and EpiLCs, indicating epigenetic resetting of regulatory elements. Accordingly, we show that NANOG can bind and activate enhancers of Prdm1 and Prdm14 in EpiLCs in vitro; BLIMP1 (encoded by Prdm1) then directly induces Tfap2c. Furthermore, while SOX2 and NANOG promote the pluripotent state in ESCs, they show contrasting roles in EpiLCs since Sox2 specifically represses PGCLC induction by Nanog. This study demonstrates a broadly applicable mechanistic principle for how cells acquire competence for cell fate determination, resulting in the context-dependent roles of key transcription factors during development.
Project description:Nanog, a core pluripotency factor in the inner cell mass of blastocysts, is also expressed in unipotent primordial germ cells (PGC) in mice1, where its precise role is yet unclear2-4. We investigated this in an in vitro model, where naïve pluripotent embryonic stem cells (ESCs) cultured in bFGF/ActivinA develop as epiblast-like cells (EpiLCs), and gain competence for PGC-like fate5. Consequently, bone morphogenetic protein (BMP4), or ectopic expression of key germline transcription factors Prdm1/ Prdm14/ Tfap2c, directly induce PGC-like cells (PGCLCs) in EpiLCs, but not in ESCs6-8. Here we report an unexpected discovery that Nanog alone can induce PGCLCs in EpiLCs, independently of BMP4. We propose that following the dissolution of the naïve ESC pluripotency network during establishment of EpiLCs9,10, the epigenome is reset for cell fate determination. Indeed, we found genome-wide changes in NANOG binding pattern between ESCs and EpiLCs, indicating epigenetic resetting of regulatory elements. Accordingly, we show that NANOG can bind and activate enhancers of Prdm1 and Prdm14 in EpiLCs in vitro; BLIMP1 (encoded by Prdm1) then directly induces Tfap2c. Furthermore, while SOX2 and NANOG promote the pluripotent state in ESCs, they show contrasting roles in EpiLCs since Sox2 specifically represses PGCLC induction by Nanog. This study demonstrates a broadly applicable mechanistic principle for how cells acquire competence for cell fate determination, resulting in the context-dependent roles of key transcription factors during development.