scholarly journals Species-specific pace of development is associated with differences in protein stability

Science ◽  
2020 ◽  
Vol 369 (6510) ◽  
pp. eaba7667 ◽  
Author(s):  
Teresa Rayon ◽  
Despina Stamataki ◽  
Ruben Perez-Carrasco ◽  
Lorena Garcia-Perez ◽  
Christopher Barrington ◽  
...  
Keyword(s):  
Protein Stability ◽  
Motor Neurons ◽  
Molecular Mechanisms ◽  
Genomic Sequence ◽  
Embryonic Stem ◽  
Fold Increase ◽  
Regulatory Elements ◽  
Cycle Duration ◽  
Species Specific

Although many molecular mechanisms controlling developmental processes are evolutionarily conserved, the speed at which the embryo develops can vary substantially between species. For example, the same genetic program, comprising sequential changes in transcriptional states, governs the differentiation of motor neurons in mouse and human, but the tempo at which it operates differs between species. Using in vitro directed differentiation of embryonic stem cells to motor neurons, we show that the program runs more than twice as fast in mouse as in human. This is not due to differences in signaling, nor the genomic sequence of genes or their regulatory elements. Instead, there is an approximately two-fold increase in protein stability and cell cycle duration in human cells compared with mouse cells. This can account for the slower pace of human development and suggests that differences in protein turnover play a role in interspecies differences in developmental tempo.

scholarly journals Species-specific developmental timing is associated with global differences in protein stability in mouse and human

2019 ◽  
Author(s):  
Teresa Rayon ◽  
Despina Stamataki ◽  
Ruben Perez-Carrasco ◽  
Lorena Garcia-Perez ◽  
Christopher Barrington ◽  
...  
Keyword(s):  
Protein Stability ◽  
Motor Neurons ◽  
Molecular Mechanisms ◽  
Genomic Sequence ◽  
Embryonic Stem ◽  
Fold Increase ◽  
Regulatory Elements ◽  
Cycle Duration ◽  
Species Specific

ABSTRACTWhat determines the pace of embryonic development? Although many molecular mechanisms controlling developmental processes are evolutionarily conserved, the speed at which these operate can vary substantially between species. For example, the same genetic programme, comprising sequential changes in transcriptional states, governs the differentiation of motor neurons in mouse and human, but the tempo at which it operates differs between species. Using in vitro directed differentiation of embryonic stem cells to motor neurons, we show that the programme runs twice as fast in mouse as in human. We provide evidence that this is neither due to differences in signalling, nor the genomic sequence of genes or their regulatory elements. Instead, we find an approximately two-fold increase in protein stability and cell cycle duration in human cells compared to mouse. This can account for the slower pace of human development, indicating that global differences in key kinetic parameters play a major role in interspecies differences in developmental tempo.

scholarly journals Understanding the Half-Life Extension of Intravitreally Administered Antibodies Binding to Ocular Albumin

Pharmaceutics ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 810
Author(s):  
Simon Hauri ◽  
Paulina Jakubiak ◽  
Matthias Fueth ◽  
Stefan Dengl ◽  
Sara Belli ◽  
...  
Keyword(s):  
Serum Albumin ◽  
Half Life ◽  
Molecular Mechanisms ◽  
Fold Increase ◽  
Size Exclusion ◽  
Life Extension ◽  
Long Acting ◽  
Species Specific

The burden associated with frequent injections of current intravitreal (IVT) therapeutics may be reduced by long-acting delivery strategies. Binding to serum albumin has been shown to extend the ocular half-life in rabbits, however, the underlying molecular mechanisms and translational relevance remain unclear. The aim of this work was to characterize the in vitro and in vivo formation of complexes between human serum albumin (HSA) and an antigen-binding fragment of a rabbit antibody linked to an anti-HSA nanobody (FabA). The ocular and systemic pharmacokinetics of 3H-labeled FabA (0.05 mg/eye IVT) co-formulated with HSA (1 and 15 nmol/eye) were assessed in Dutch belted rabbits. Next, FabA was incubated in vitreous samples from cynomolgus monkeys and human donors (healthy and diseased) supplemented with species-specific serum albumin. Finally, the FabA-albumin complexes formed in vitro and in vivo were analyzed by radio-size exclusion chromatography. A 3-fold increase in FabA vitreal exposure and half-life was observed in rabbits co-administered with 15 nmol HSA compared to 1 nmol and a control arm. The different pharmacokinetic behavior was explained with the formation of higher molecular weight FabA–albumin complexes. The analysis of vitreous samples revealed the existence of predominantly 1:1 complexes at endogenous or low concentrations of supplemented albumin. A shift towards 1:2 complexes was observed with increasing albumin concentrations. Overall, these results suggest that endogenous vitreal albumin concentrations are insufficient for half-life extension and warrant supplementation in the dosing formulation.

scholarly journals The TGFβ Family in Human Placental Development at the Fetal-Maternal Interface

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 453
Author(s):  
Susana M. Chuva de Sousa Lopes ◽  
Marta S. Alexdottir ◽  
Gudrun Valdimarsdottir
Keyword(s):  
Stem Cell ◽  
Transforming Growth Factor Beta ◽  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Cell Model ◽  
Embryonic Stem ◽  
Model Systems ◽  
Special Focus ◽  
Placental Development

Emerging data suggest that a trophoblast stem cell (TSC) population exists in the early human placenta. However, in vitro stem cell culture models are still in development and it remains under debate how well they reflect primary trophoblast (TB) cells. The absence of robust protocols to generate TSCs from humans has resulted in limited knowledge of the molecular mechanisms that regulate human placental development and TB lineage specification when compared to other human embryonic stem cells (hESCs). As placentation in mouse and human differ considerably, it is only with the development of human-based disease models using TSCs that we will be able to understand the various diseases caused by abnormal placentation in humans, such as preeclampsia. In this review, we summarize the knowledge on normal human placental development, the placental disease preeclampsia, and current stem cell model systems used to mimic TB differentiation. A special focus is given to the transforming growth factor-beta (TGFβ) family as it has been shown that the TGFβ family has an important role in human placental development and disease.

A novel epithelial cell from neonatal rat lung: isolation and differentiated phenotype

1990 ◽  
Vol 259 (6) ◽  
pp. L415-L425 ◽  
Author(s):  
P. E. Roberts ◽  
D. M. Phillips ◽  
J. P. Mather
Keyword(s):  
Epithelial Cell ◽  
Molecular Mechanisms ◽  
Basal Medium ◽  
Fold Increase ◽  
Cell Types ◽  
Cell Number ◽  
Neonatal Rat ◽  
Rat Lung ◽  
Cell Type

A novel epithelial cell from normal neonatal rat lung has been isolated, established, and maintained for multiple passages in the absence of serum, without undergoing crisis or senescence. By careful manipulation of the nutrition/hormonal microenvironment, we have been able to select, from a heterogeneous population, a single epithelial cell type that can maintain highly differentiated features in vitro. This cell type has characteristics of bronchiolar epithelial cells. A clonal line, RL-65, has been selected and observed for greater than 2 yr in continuous culture. It has been characterized by ultrastructural, morphological, and biochemical criteria. The basal medium for this cell line is Ham's F12/Dulbecco's modified Eagle's (DME) medium plus insulin (1 micrograms/ml), human transferrin (10 micrograms/ml), ethanolamine (10(-4) M), phosphoethanolamine (10(-4) M), selenium (2.5 x 10(-8) M), hydrocortisone (2.5 x 10(-7) M), and forskolin (5 microM). The addition of 150 micrograms/ml of bovine pituitary extract to the defined basal medium stimulates a greater than 10-fold increase in cell number and a 50- to 100-fold increase in thymidine incorporation. The addition of retinoic acid results in further enhancement of cell growth and complete inhibition of keratinization. We have demonstrated a strategy that may be applicable to isolating other cell types from the lung and maintaining their differentiated characteristics for long-term culture in vitro. Such a culture system promises to be a useful model in which to study cellular events associated with differentiation and proliferation in the lung and to better understand the molecular mechanisms involved in these events.

scholarly journals Maturation of Embryonic Stem Cells Into Endothelial Cells in an In Vitro Model of Vasculogenesis

Blood ◽  
1999 ◽  
Vol 93 (4) ◽  
pp. 1253-1263 ◽  
Author(s):  
Masanori Hirashima ◽  
Hiroshi Kataoka ◽  
Satomi Nishikawa ◽  
Norihisa Matsuyoshi ◽  
Shin-Ichi Nishikawa
Keyword(s):  
Cell Adhesion ◽  
Endothelial Cell ◽  
Growth Factor ◽  
Culture System ◽  
Molecular Mechanisms ◽  
Es Cells ◽  
Embryonic Stem ◽  
Vascular Endothelial ◽  
Cell Cell

A primitive vascular plexus is formed through coordinated regulation of differentiation, proliferation, migration, and cell-cell adhesion of endothelial cell (EC) progenitors. In this study, a culture system was devised to investigate the behavior of purified EC progenitors in vitro. Because Flk-1+ cells derived from ES cells did not initially express other EC markers, they were sorted and used as EC progenitors. Their in vitro differentiation into ECs, via vascular endothelial-cadherin (VE-cadherin)+ platelet-endothelial cell adhesion molecule-1 (PECAM-1)+ CD34−to VE-cadherin+ PECAM-1+CD34+ stage, occurred without exogenous factors, whereas their proliferation, particularly at low cell density, required OP9 feeder cells. On OP9 feeder layer, EC progenitors gave rise to sheet-like clusters of Flk-1+ cells, with VE-cadherin concentrated at the cell-cell junction. The growth was suppressed by Flt-1-IgG1 chimeric protein and dependent on vascular endothelial growth factor (VEGF) but not placenta growth factor (PIGF). Further addition of VEGF resulted in cell dispersion, indicating the role of VEGF in the migration of ECs as well as their proliferation. Cell-cell adhesion of ECs in this culture system was mediated by VE-cadherin. Thus, the culture system described here is useful in dissecting the cellular events of EC progenitors that occur during vasculogenesis and in investigating the molecular mechanisms underlying these processes.

scholarly journals The chromatin, topological and regulatory properties of pluripotency-associated poised enhancers are conserved in vivo

2021 ◽  
Author(s):  
Giuliano Crispatzu ◽  
Rizwan Rehimi ◽  
Tomas Pachano ◽  
Tore Bleckwehl ◽  
Sara de la Cruz Molina ◽  
...  
Keyword(s):  
Embryonic Stem ◽  
Regulatory Elements ◽  
Small Subset ◽  
Regulatory Sequences ◽  
Pluripotent Cells ◽  
Developmental Genes ◽  
Topological Features ◽  
Regulatory Properties

AbstractPoised enhancers (PEs) represent a limited and genetically distinct set of distal regulatory elements that control the induction of developmental genes in a hierarchical and non-redundant manner. Before becoming activated in differentiating cells, PEs are already bookmarked in pluripotent cells with unique chromatin and topological features that could contribute to their privileged regulatory properties. However, since PEs were originally identified and subsequently characterized using embryonic stem cells (ESC) as an in vitro differentiation system, it is currently unknown whether PEs are functionally conserved in vivo. Here, we generate and mine various types of genomic data to show that the chromatin and 3D structural features of PEs are conserved among mouse pluripotent cells both in vitro and in vivo. We also uncovered that, in mouse pluripotent cells, the interactions between PEs and their bivalent target genes are globally controlled by the combined action of Polycomb, Trithorax and architectural proteins. Moreover, distal regulatory sequences located close to developmental genes and displaying the typical genetic (i.e. proximity to CpG islands) and chromatin (i.e. high accessibility and H3K27me3 levels) features of PEs are commonly found across vertebrates. These putative PEs show high sequence conservation, preferentially within specific vertebrate clades, with only a small subset being evolutionary conserved across all vertebrates. Lastly, by genetically disrupting evolutionary conserved PEs in mouse and chicken embryos, we demonstrate that these regulatory elements play essential and non-redundant roles during the induction of major developmental genes in vivo.

scholarly journals Hydroxytyrosol Plays Antiatherosclerotic Effects through Regulating Lipid Metabolism via Inhibiting the p38 Signal Pathway

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xinxin Zhang ◽  
Yating Qin ◽  
Xiaoning Wan ◽  
Hao Liu ◽  
Chao Iv ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Molecular Mechanisms ◽  
Cholesterol Metabolism ◽  
Fold Increase ◽  
Heart Tissue ◽  
Control Group ◽  
Atherosclerotic Lesions ◽  
Serum Crp

Purpose. Hydroxytyrosol (HT) processes multiaspect pharmacological properties such as antithrombosis and antidiabetes. The aim of this study was to explore the antistherosclerotic roles and relevant mechanisms of HT. Methods. Male apoE-/- mice were randomly divided into 2 groups: the control group and the HT group (10 mg/kg/day orally). After 16 weeks, blood tissue, heart tissue, and liver tissue were obtained to detect the atherosclerotic lesions, histological analysis, lipid parameters, and inflammation. And the underlying molecular mechanisms of HT were also studied in vivo and in vitro. Results. HT administration significantly reduced the extent of atherosclerotic lesions in the aorta of apoE-/- mice. We found that HT markedly lowered the levels of serum TG, TC, and LDL-C approximately by 17.4% (p=0.004), 15.2% (p=0.003), and 17.9% (p=0.009), respectively, as well as hepatic TG and TC by 15.0% (p<0.001) and 12.3% (p=0.003), respectively, while inducing a 26.9% (p=0.033) increase in serum HDL-C. Besides, HT improved hepatic steatosis and lipid deposition. Then, we discovered that HT could regulate the signal flow of AMPK/SREBP2 and increase the expression of ABCA1, apoAI, and SRBI. In addition, HT reduced the levels of serum CRP, TNF-α, IL-1β, and IL-6 approximately by 23.5% (p<0.001), 27.8% (p<0.001), 18.4% (p<0.001), and 19.1% (p<0.001), respectively, and induced a 1.4-fold increase in IL-10 level (p=0.014). Further, we found that HT might regulate cholesterol metabolism via decreasing phosphorylation of p38, followed by activation of AMPK and inactivation of NF-κB, which in turn triggered the blockade of SREBP2/PCSK9 and upregulation of LDLR, apoAI, and ABCA1, finally leading to a reduction of LDL-C and increase of HDL-C in the circulation. Conclusion. Our results provide the first evidence that HT displays antiatherosclerotic actions via mediating lipid metabolism-related pathways through regulating the activities of inflammatory signaling molecules.

scholarly journals Rational engineering of 2-deoxyribose-5-phosphate aldolases for the biosynthesis of (R)-1,3-butanediol

2019 ◽  
Vol 295 (2) ◽  
pp. 597-609 ◽  
Author(s):  
Taeho Kim ◽  
Peter J. Stogios ◽  
Anna N. Khusnutdinova ◽  
Kayla Nemr ◽  
Tatiana Skarina ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Thermotoga Maritima ◽  
Fold Increase ◽  
Site Directed Mutagenesis ◽  
Bacillus Halodurans ◽  
Active Site Residues ◽  
Carbon Carbon Bond ◽  
Condensation Activity

Carbon–carbon bond formation is one of the most important reactions in biocatalysis and organic chemistry. In nature, aldolases catalyze the reversible stereoselective aldol addition between two carbonyl compounds, making them attractive catalysts for the synthesis of various chemicals. In this work, we identified several 2-deoxyribose-5-phosphate aldolases (DERAs) having acetaldehyde condensation activity, which can be used for the biosynthesis of (R)-1,3-butanediol (1,3BDO) in combination with aldo-keto reductases (AKRs). Enzymatic screening of 20 purified DERAs revealed the presence of significant acetaldehyde condensation activity in 12 of the enzymes, with the highest activities in BH1352 from Bacillus halodurans, TM1559 from Thermotoga maritima, and DeoC from Escherichia coli. The crystal structures of BH1352 and TM1559 at 1.40–2.50 Å resolution are the first full-length DERA structures revealing the presence of the C-terminal Tyr (Tyr224 in BH1352). The results from structure-based site-directed mutagenesis of BH1352 indicated a key role for the catalytic Lys155 and other active-site residues in the 2-deoxyribose-5-phosphate cleavage and acetaldehyde condensation reactions. These experiments also revealed a 2.5-fold increase in acetaldehyde transformation to 1,3BDO (in combination with AKR) in the BH1352 F160Y and F160Y/M173I variants. The replacement of the WT BH1352 by the F160Y or F160Y/M173I variants in E. coli cells expressing the DERA + AKR pathway increased the production of 1,3BDO from glucose five and six times, respectively. Thus, our work provides detailed insights into the molecular mechanisms of substrate selectivity and activity of DERAs and identifies two DERA variants with enhanced activity for in vitro and in vivo 1,3BDO biosynthesis.

scholarly journals Pluripotency and Epigenetic Factors in Mouse Embryonic Stem Cell Fate Regulation

2015 ◽  
Vol 35 (16) ◽  
pp. 2716-2728 ◽  
Author(s):  
Lluis Morey ◽  
Alexandra Santanach ◽  
Luciano Di Croce
Keyword(s):  
Cell Fate ◽  
Cancer Progression ◽  
Molecular Mechanisms ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cell ◽  
Basic Research ◽  
Cell Types ◽  
Pluripotency Factors ◽  
Perfect System

Embryonic stem cells (ESCs) are characterized by their ability to self-renew and to differentiate into all cell types of a given organism. Understanding the molecular mechanisms that govern the ESC state is of great interest not only for basic research—for instance, ESCs represent a perfect system to study cellular differentiationin vitro—but also for their potential implications in human health, as these mechanisms are likewise involved in cancer progression and could be exploited in regenerative medicine. In this minireview, we focus on the latest insights into the molecular mechanisms mediated by the pluripotency factors as well as their roles during differentiation. We also discuss recent advances in understanding the function of the epigenetic regulators, Polycomb and MLL complexes, in ESC biology.

scholarly journals Phosphomimetic Mutation of Ser-187 of SNAP-25 Increases both Syntaxin Binding and Highly Ca2+-sensitive Exocytosis

2007 ◽  
Vol 129 (3) ◽  
pp. 233-244 ◽  
Author(s):  
Yan Yang ◽  
Tim J. Craig ◽  
Xiaohui Chen ◽  
Leonora F. Ciufo ◽  
Masami Takahashi ◽  
...  
Keyword(s):  
Chromaffin Cells ◽  
Molecular Mechanisms ◽  
Semliki Forest Virus ◽  
Uv Light ◽  
Phosphorylation Site ◽  
Fold Increase ◽  
Readily Releasable Pool ◽  
Synaptotagmin I ◽  
Adrenal Chromaffin

The phosphorylation targets that mediate the enhancement of exocytosis by PKC are unknown. PKC phosporylates the SNARE protein SNAP-25 at Ser-187. We expressed mutants of SNAP-25 using the Semliki Forest Virus system in bovine adrenal chromaffin cells and then directly measured the Ca2+ dependence of exocytosis using photorelease of caged Ca2+ together with patch-clamp capacitance measurements. A flash of UV light used to elevate [Ca2+]i to several μM and release the highly Ca2+-sensitive pool (HCSP) of vesicles was followed by a train of depolarizing pulses to elicit exocytosis from the less Ca2+-sensitive readily releasable pool (RRP) of vesicles. Carbon fiber amperometry confirmed that the amount and kinetics of catecholamine release from individual granules were similar for the two phases of exocytosis. Mimicking PKC phosphorylation with expression of the S187E SNAP-25 mutant resulted in an approximately threefold increase in the HCSP, whereas the response to depolarization increased only 1.5-fold. The phosphomimetic S187D mutation resulted in an ∼1.5-fold increase in the HCSP but a 30% smaller response to depolarization. In vitro binding assays with recombinant SNARE proteins were performed to examine shifts in protein–protein binding that may promote the highly Ca2+-sensitive state. The S187E mutant exhibited increased binding to syntaxin but decreased Ca2+-independent binding to synaptotagmin I. Mimicking phosphorylation of the putative PKA phosphorylation site of SNAP-25 with the T138E mutation decreased binding to both syntaxin and synaptotagmin I in vitro. Expressing the T138E/ S187E double mutant in chromaffin cells demonstrated that enhancing the size of the HCSP correlates with an increase in SNAP-25 binding to syntaxin in vitro, but not with Ca2+-independent binding of SNAP-25 to synaptotagmin I. Our results support the hypothesis that exocytosis triggered by lower Ca2+ concentrations (from the HCSP) occurs by different molecular mechanisms than exocytosis triggered by higher Ca2+ levels.

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