FGF inhibition directs BMP4-mediated differentiation of human embryonic stem cells to syncytiotrophoblast

Bone morphogenetic protein (BMP) signaling is known to support differentiation of human embryonic stem cells (hESCs) into mesoderm and extraembryonic lineages, whereas other signaling pathways can largely influence this lineage specification. Here, we set out to reinvestigate the influence of ACTIVIN/NODAL and fibroblast growth factor (FGF) pathways on the lineage choices made by hESCs during BMP4-driven differentiation. We show that BMP activation, coupled with inhibition of both ACTIVIN/NODAL and FGF signaling, induces differentiation of hESCs, specifically to betahCG hormone-secreting multinucleated syncytiotrophoblast and does not support induction of embryonic and extraembryonic lineages, extravillous trophoblast, and primitive endoderm. It has been previously reported that FGF2 can switch BMP4-induced hESC differentiation outcome to mesendoderm. Here, we show that FGF inhibition alone, or in combination with either ACTIVIN/NODAL inhibition or BMP activation, supports hESC differentiation to hCG-secreting syncytiotrophoblast. We show that the inhibition of the FGF pathway acts as a key in directing BMP4-mediated hESC differentiation to syncytiotrophoblast

Estrogens Determine Adherens Junction Organization and E-Cadherin Clustering in Breast Cancer Cells via Amphiregulin

Estrogens play an important role in the development and progression of human cancers, particularly in breast cancer. Breast cancer progression depends on the malignant destabilization of adherens junctions (AJs) and disruption of tissue integrity. We found that estrogen receptor alpha (ER alpha) inhibition led to a striking spatial reorganization of AJs and microclustering of E-Cadherin (E-Cad) in the cell membrane of breast cancer cells. This resulted in increased stability of AJs and cell stiffness and a reduction of cell motility. These effects were actomyosindependent and reversible by estrogens. Detailed investigations showed that the ERa target gene and epidermal growth factor receptor (EGFR) ligand Amphiregulin (AREG) essentially regulates AJ reorganization and E-Cad microclustering. Our results not only describe a biological mechanism for the organization of AJs and the modulation of mechanical properties of cells but also provide a new perspective on how estrogens and anti-estrogens might influence the formation of breast tumors

Metabolic enhancement of mammalian developmental pausing

The quest to model and modulate embryonic development became a recent cornerstone of stem cell and developmental biology. Mammalian developmental timing is adjustable in vivo by preserving preimplantation embryos in a dormant state called diapause. Inhibition of the growth regulator mTOR (mTORi) pauses mouse development in vitro, yet constraints to pause duration are unrecognized. By comparing the response of embryonic and extraembryonic stem cells to mTORi-induced pausing, we identified lipid usage as a bottleneck to developmental pausing. Enhancing fatty acid oxidation (FAO) boosts embryo longevity, while blocking it reduces the pausing capacity. Genomic and metabolic analyses of single embryos point toward a deeper dormant state in FAO-enhanced pausing and reveal a link between lipid metabolism and embryo morphology. Our results lift a constraint on in vitro embryo survival and suggest that lipid metabolism may be a critical metabolic transition relevant for longevity and stem cell function across tissues

Astrophysical S-factor for the radiative capture reaction 13C(p,g)14N

The phase shift analysis, done on the basis of the known measurements of the differential cross-sections of the p13C elastic scattering at the energy range 250-750 keV, shows that it is enough to take into account only 3S1 wave in the considered energy region. The potential for the triplet 3S1 state in p13C system at the resonance energy 0.55 MeV corresponding to quantum numbers JpT = 1-1 as well as the potential for the 3P1 bound state of 14N were constructed on the basis of the obtained scattering phase shifts. The possibility to describe the experimental data of the astrophysical S-factor of the p13C radiative capture at the energies 0.03-0.8 MeV was considered within the potential cluster model with the forbidden states. It was shown that we properly succeed in explanation of the energy behavior of the astrophysical S-factor for the p13C radiative capture at the resonance energy range 0.55 MeV (laboratory system).Comment: 8 p., 2 fi

Timed global reorganization of protein synthesis during neocortex neurogenesis at codon resolution

Translation modulates the timing and amplification of gene expression after transcription. Development of the brain’s neocortex requires precisely timed and spatially targeted gene expression, but the relationship between mRNA vs. protein synthesis throughout the genome is unknown. We perform a comprehensive analysis of the reactants, synthesis, and products of mRNA translation spanning mouse neocortex neurogenesis. Ribosome number in the cortical plate decreases sharply at mid-neurogenesis during a transition in neuronal subtype specification, shifting the fundamental kinetics of protein synthesis, with mRNA and protein levels frequently divergent. Satb2, which drives an essential neuronal subtype-specific program, is a highly dynamically translated mRNA with surprisingly broad transcription across diverse neuronal lineages. Satb2 protein achieves its neuronal subtype expression through timed regulation by the RNA-binding protein Pumilio2. Thus, the refinement of transcriptional programs by protein synthesis is a widespread feature of neuronal specification. Developmental neocortex translatome data are provided in an open-source resource: https://shiny.mdc-berlin.de/cortexomics/

A critical period of translational control during brain development at codon resolution

Translation modulates the timing and amplification of gene expression after transcription. Brain development requires uniquely complex gene expression patterns, but large-scale measurements of translation directly in the prenatal brain are lacking. We measure the reactants, synthesis and products of mRNA translation spanning mouse neocortex neurogenesis, and discover a transient window of dynamic regulation at mid-gestation. Timed translation upregulation of chromatin-binding proteins like Satb2, which is essential for neuronal subtype differentiation, restricts protein expression in neuronal lineages despite broad transcriptional priming in progenitors. In contrast, translation downregulation of ribosomal proteins sharply decreases ribosome biogenesis, coinciding with a major shift in protein synthesis dynamics at mid-gestation. Changing activity of eIF4EBP1, a direct inhibitor of ribosome biogenesis, is concurrent with ribosome downregulation and affects neurogenesis of the Satb2 lineage. Thus, the molecular logic of brain development includes the refinement of transcriptional programs by translation. Modeling of the developmental neocortex translatome is provided as an open-source searchable resource at https://shiny.mdc-berlin.de/cortexomics

First international descriptive and interventional survey for cholesterol and non-cholesterol sterol determination by gas- and liquid- chromatography–Urgent need for harmonisation of analytical methods

Serum concentrations of lathosterol, the plant sterols campesterol and sitosterol and the cholesterol metabolite 5α-cholestanol are widely used as surrogate markers of cholesterol synthesis and absorption, respectively. Increasing numbers of laboratories utilize a broad spectrum of well-established and recently developed methods for the determination of cholesterol and non-cholesterol sterols (NCS). In order to evaluate the quality of these measurements and to identify possible sources of analytical errors our group initiated the first international survey for cholesterol and NCS. The cholesterol and NCS survey was structured as a two-part survey which took place in the years 2013 and 2014. The first survey part was designed as descriptive, providing information about the variation of reported results from different laboratories. A set of two lyophilized pooled sera (A and B) was sent to twenty laboratories specialized in chromatographic lipid analysis. The different sterols were quantified either by gas chromatography-flame ionization detection, gas chromatography- or liquid chromatography-mass selective detection. The participants were requested to determine cholesterol and NCS concentrations in the provided samples as part of their normal laboratory routine. The second part was designed as interventional survey. Twenty-two laboratories agreed to participate and received again two different lyophilized pooled sera (C and D). In contrast to the first international survey, each participant received standard stock solutions with defined concentrations of cholesterol and NCS. The participants were requested to use diluted calibration solutions from the provided standard stock solutions for quantification of cholesterol and NCS. In both surveys, each laboratory used its own internal standard (5α-cholestane, epicoprostanol or deuterium labelled sterols). Main outcome of the survey was, that unacceptably high interlaboratory variations for cholesterol and NCS concentrations are reported, even when the individual laboratories used the same calibration material. We discuss different sources of errors and recommend all laboratories analysing cholesterol and NCS to participate in regular quality control programs

Stem Cells

The ability of stem cells to propagate indefinitely is believed to occur via the fine modulation of pathways commonly involved in cellular senescence, including the telomerase, the p53, and the mitochondrial/oxidative stress pathways. Induced pluripotent stem cells (iPSCs) are a novel stem cell population obtained from somatic cells through forced expression of a set of genes normally expressed in embryonic stem cells (ESCs). These reprogrammed cells acquire self-renewal properties and appear almost undistinguishable from ESCs in terms of morphology, gene expression, and differentiation potential. Accordingly, iPSCs exhibit alterations of the senescence-related telomerase and p53 signaling pathways. However, although treatments with antioxidants have been recently shown to enhance cellular reprogramming, detailed information regarding the state of the mitochondrial/oxidative stress pathway in iPSCs is still lacking. Mitochondria undergo specific changes during organismal development and aging. Thus, addressing whether somatic mitochondria within iPSCs acquire ESC-like features or retain the phenotype of the parental cell is an unanswered but relevant question. Herein, we demonstrate that somatic mitochondria within human iPSCs revert to an immature ESC-like state with respect to organelle morphology and distribution, expression of nuclear factors involved in mitochondrial biogenesis, content of mitochondrial DNA, intracellular ATP level, oxidative damage, and lactate generation. Upon differentiation, mitochondria within iPSCs and ESCs exhibited analogous maturation and anaerobic-to-aerobic metabolic modifications. Overall, the data highlight that human iPSCs and ESCs, although not identical, share similar mitochondrial properties and suggest that cellular reprogramming can modulate the mitochondrial/oxidative stress pathway, thus inducing a rejuvenated state capable of escaping cellular senescence