MicroRNA 630 Represses NANOG Expression through Transcriptional and Post-Transcriptional Regulation in Human Embryonal Carcinoma Cells

The pluripotent transcription factor NANOG is essential for maintaining embryonic stem cells and driving tumorigenesis. We previously showed that PKC activity is involved in the regulation of NANOG expression. To explore the possible involvement of microRNAs in regulating the expression of key pluripotency factors, we performed a genome-wide analysis of microRNA expression in the embryonal carcinoma cell line NT2/D1 in the presence of the PKC activator, PMA. We found that MIR630 was significantly upregulated in PMA-treated cells. Experimentally, we showed that transfection of MIR630 mimic into embryonal carcinoma cell lines directly targeted the 3′UTR of OCT4, SOX2, and NANOG and markedly suppressed their expression. RNAhybrid and RNA22 algorithms were used to predict miRNA target sites in the NANOG 3’UTR, four possible target sites of MIR630 were identified. To examine the functional interaction between MIR630 and NANOG mRNA, the predicted MIR630 target sites in the NANOG 3’UTR were deleted and the activity of the reporters were compared. After targeted mutation of the predicted MIR630 target sites, the MIR630 mimic inhibited NANOG significantly less than the wild-type reporters. It is worth noting that mutation of a single putative binding site in the 3’UTR of NANOG did not completely abolish MIR630-mediated suppression, suggesting that MIR630 in the NANOG 3’UTR may have multiple binding sites and act together to maximally repress NANOG expression. Interestingly, MIR630 mimics significantly downregulated NANOG gene transcription. Exogenous expression of OCT4, SOX2, and NANOG lacking the 3’UTR almost completely rescued the reduced transcriptional activity of MIR630. MIR630 mediated the expression of differentiation markers in NT2/D1 cells, suggesting that MIR630 leads to the differentiation of NT2/D1 cell. Our findings show that MIR630 represses NANOG through transcriptional and post-transcriptional regulation, suggesting a direct link between core pluripotency factors and MIR630.

Satb2 acts as a gatekeeper for major developmental transitions during early vertebrate embryogenesis

Zygotic genome activation (ZGA) initiates regionalized transcription underlying distinct cellular identities. ZGA is dependent upon dynamic chromatin architecture sculpted by conserved DNA-binding proteins. However, the direct mechanistic link between the onset of ZGA and the tissue-specific transcription remains unclear. Here, we have addressed the involvement of chromatin organizer Satb2 in orchestrating both processes during zebrafish embryogenesis. Integrative analysis of transcriptome, genome-wide occupancy and chromatin accessibility reveals contrasting molecular activities of maternally deposited and zygotically synthesized Satb2. Maternal Satb2 prevents premature transcription of zygotic genes by influencing the interplay between the pluripotency factors. By contrast, zygotic Satb2 activates transcription of the same group of genes during neural crest development and organogenesis. Thus, our comparative analysis of maternal versus zygotic function of Satb2 underscores how these antithetical activities are temporally coordinated and functionally implemented highlighting the evolutionary implications of the biphasic and bimodal regulation of landmark developmental transitions by a single determinant.

A novel cis regulatory element regulates human XIST in CTCF-dependent manner

The long non-coding RNA XIST is the master regulator for the process of X chromosome inactivation (XCI) in mammalian females. Here we report the existence of a hitherto uncharacterized cis regulatory element (cRE) within the first exon of human XIST , which determines the transcriptional status of XIST during the initiation and maintenance phases of XCI. In the initiation phase, pluripotency factors bind to this cRE and keep XIST repressed. In the maintenance phase of XCI, the cRE is enriched for CTCF which activates XIST transcription. By employing a CRISPR-dCas9-KRAB based interference strategy, we demonstrate that binding of CTCF to the newly identified cRE is critical for regulating XIST in a YY1-dependent manner. Collectively, our study uncovers the combinatorial effect of multiple transcriptional regulators influencing XIST expression during the initiation and maintenance phases of XCI.

Partial reprogramming restores youthful gene expression through transient suppression of cell identity

Transient induction of pluripotent reprogramming factors has been reported to reverse some features of aging in mammalian cells and tissues. However, the impact of transient reprogramming on somatic cell identity programs and the necessity of individual pluripotency factors remain unknown. Here, we mapped trajectories of transient reprogramming in young and aged cells from multiple murine cell types using single cell transcriptomics to address these questions. We found that transient reprogramming restored youthful gene expression in adipocytes and mesenchymal stem cells but also temporarily suppressed somatic cell identity programs. We further screened Yamanaka Factor subsets and found that many combinations had an impact on aging gene expression and suppressed somatic identity, but that these effects were not tightly entangled. We also found that a transient reprogramming approach inspired by amphibian regeneration restored youthful gene expression in aged myogenic cells. Our results suggest that transient pluripotent reprogramming poses a neoplastic risk, but that restoration of youthful gene expression can be achieved with alternative strategies.

Culturing of human pluripotent stem cells in a mesoderm biased state

Here we present a new culturing system, PRIMO Plus, to generate mesoderm biased human pluripotent stem cells by cross antagonism of pro-differentiation and pro-pluripotency factors in a fully defined medium.

Glycolysis Combined with Core Pluripotency Factors to Promote the Formation of Chicken Induced Pluripotent Stem Cells

Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) in vitro. Previously, a lentivirus induction strategy of introducing Oct4, Sox2, Nanog and Lin28 (OSNL) into the iPSC process has been shown as a possible way to produce chicken iPSCs from chicken embryonic fibroblasts, but the induction efficiency of this method was found to be significantly limiting. In order to help resolve this efficiency obstacle, this study seeks to clarify the associated regulation mechanisms and optimizes the reprogramming strategy of chicken iPSCs. This study showed that glycolysis and the expression of glycolysis-related genes correlate with a more efficient reprogramming process. At the same time, the transcription factors Oct4, Sox2 and Nanog were found to activate the expression of glycolysis-related genes. In addition, we introduced two small-molecule inhibitors (2i-SP) as a “glycolysis activator” together with the OSNL cocktail, and found that this significantly improved the induction efficiency of the iPSC process. As such, the study identifies direct molecular connections between core pluripotency factors and glycolysis during the chicken iPSC induction process and, with its results, provides a theoretical basis and technical support for chicken somatic reprogramming.

Monolayer platform to generate and purify human primordial germ cells in vitro provides new insights into germline specification

Generating primordial germ cells (PGCs) from human pluripotent stem cells (hPSCs) advances studies of human reproduction and development of infertility treatments, but currently entails complex 3D aggregates. Here we develop a simplified, monolayer method to differentiate hPSCs into PGCs within 3.5 days. We used our simplified differentiation platform and single-cell RNA-sequencing to uncover new insights into PGC specification. Transient WNT activation for 12 hours followed by WNT inhibition specified PGCs; by contrast, sustained WNT instead induced primitive streak. Thus, somatic (primitive streak) and PGCs are related—yet distinct—lineages segregated by temporally-dynamic signaling. Pluripotency factors including NANOG are continuously expressed during the transition from pluripotency to posterior epiblast to PGCs, thus bridging pluripotent and germline states. Finally, hPSC-derived PGCs can be easily purified by virtue of their CXCR4+PDGFRA−GARP− surface-marker profile and single-cell RNA-sequencing reveals that they harbor strong transcriptional similarities with fetal PGCs.

MUC1-C IS A DRUGGABLE TARGET FOR TREATMENT OF COLITIS AND PROGRESSION OF COLITIS-ASSOCIATED COLORECTAL CANCER

The MUC1-C oncoprotein evolved in mammals to protect epithelial cells, such as those lining the gastrointestinal tract, from loss of homeostasis. In this way, MUC1-C activates pathways that contribute to inflammation, proliferation and remodeling associated with the wound healing response. MUC1-C is upregulated in human tissues from inflamed ulcerative colitis (UC) mucosa as compared to that from normal and uninflamed UC mucosa. MUC1-C is also upregulated in a mouse MUC1+/-/IL-10-/- model of colitis, consistent with its involvement in the inflammatory response. MUC1-C forms a direct complex with NF-κB p65 and promotes the activation of NF-κB target genes, including MUC1 itself in an auto- inductive circuit. MUC1-C thereby drives proinflammatory NF-κB pathway genes in human inflamed UC tissues and in the genetically engineered mouse model (GEMM) of colitis. Mechanistically, MUC1-C induces the TGF-b-activated kinase 1 (TAK1), which is an essential effector of proinflammatory NF-κB signaling. Of further significance, MUC1-C drives the TAK1→NF-κB p65 pathway in human colon cancer cell lines, and MUC1 and TAK1 are upregulated in human colon cancers. These seminal findings supported the notion that MUC1-C contributes to colitis and progression to colon cancer. To extend these studies, MUC1-C was targeted with an inhibitor that blocks its homodimerization and function. Remarkably, treatment of the MUC1+/-/IL-10-/- GEMM with the GO-203 inhibitor was associated with decreases in the severity of colitis and progression of colitis to dysplasia and carcinomas. Intestinal stem cells (ISCs) that express Lgr5 are of importance in the inflammatory response to colitis and in progression to colitis-associated colorectal cancer (CACC). Targeting MUC1-C with GO-203 in mouse models of colitis suppressed Lgr5 expression, as well as induction of MYC and other core pluripotency factors. By extension to human colon cancer cells, we found that MUC1- C drives MYC with activation of LGR5 and stemness. MUC1-C also induces cancer stem cell (CSC) markers (BMI1, ALDH1, FOXA1, LIN28B) and the OCT4, SOX2, and NANOG pluripotency factors. Consistent with driving the CSC state, targeting MUC1-C suppressed the capacity of CRC cells to promote wound healing, invasion, self-renewal, and tumorigenicity. Analysis of human tissues further demonstrated that MUC1 expression associates with activation of inflammatory pathways, development of colitis, and aggressiveness of CRCs. These results collectively indicate that MUC1-C is of importance for integrating stemness and pluripotency in colitis and CRC. Of clinical relevance, the findings further indicate that MUC1-C represents a previously unrecognized target that is potentially druggable with orally administered GO-203 now being tested in the GEMMs for treating progression of colitis and CRC.

DEREGULATORY ACTION OF ENDOCRINE DISRUPTOR DDT ON MORPHOGENESIS AND FUNCTION OF ADRENAL ZONA GLOMERULOSA

Exposure to endocrine disruptor DDT impairs development of adrenal zona glomerulosa by higher expression of pluripotency factors along with the suppression of factors that ensure the maturation of cortical cells. It leads to a decrease in aldosterone production and compensatory hyperplasia of zona glomerulosa.