The axon guidance defect of the telencephalic commissures of the JSAP1-deficient brain was partially rescued by the transgenic expression of JIP1

The JNK interacting protein, JSAP1, has been identified as a scaffold protein for mitogen-activated protein kinase (MAPK) signaling pathways and as a linker protein for the cargo transport along the axons. To investigate the physiological function of JSAP1 in vivo, we generated mice lacking JSAP1. The JSAP1 null mutation produced various developmental deficits in the brain, including an axon guidance defect of the corpus callosum, in which phospho-FAK and phospho-JNK were distributed at reduced levels. The axon guidance defect of the corpus callosum in the jsap1-/- brain was correlated with the misplacement of glial sling cells, which reverted to their normal position after the transgenic expression of JNK interacting protein 1(JIP1). The transgenic JIP1 partially rescued the axon guidance defect of the corpus callosum and the anterior commissure of the jsap1-/- brain. The JSAP1 null mutation impaired the normal distribution of the Ca+2 regulating protein, calretinin, but not the synaptic vesicle marker, SNAP-25, along the axons of the thalamocortical tract. These results suggest that JSAP1 is required for the axon guidance of the telencephalic commissures and the distribution of cellular protein(s) along axons in vivo, and that the signaling network organized commonly by JIP1 and JSAP1 regulates the axon guidance in the developing brain.     

Regulation of N-cadherin-based cell-cell interaction by JSAP1 scaffold in PC12h cells

We previously reported that the level of c-Jun NH2-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1), a scaffold protein for JNK signaling, increases dramatically during nerve growth factor (NGF)-induced differentiation of PC12h cells. In the present study, we investigated the function of JSAP1 during PC12h cell differentiation by knocking down the level of JSAP1. The depletion of JSAP1 caused NGF-treated PC12h cells to form aggregates and impaired their differentiation. The aggregation was not observed in JSAP1-depleted cells that were untreated or treated with epidermal growth factor. Immunocytochemical studies indicated that N-cadherin, but not E-cadherin, was localized to sites of cell-cell contact in the aggregated cells. Furthermore, an inhibitory anti-N-cadherin antibody completely blocked the aggregation. Taken together, these results suggest that JSAP1 regulates cell-cell interactions in PC12h cells specifically in the NGF-induced signaling pathway, and does so by modulating N-cadherin.     

Regulation of p53 in embryonic stem cells

Despite an increasing interest in the role of the p53 tumour suppressor protein in embryonic stem cells, not much is known about its regulation in this cell type.We show that the relatively high amount of p53 protein correlates with a higher amount of p53 RNA in ES cells compared to differentiated cells. Moreover, p53 RNA is more stable in embryonic stem cells and the p53 protein is more often transcribed. This is at least partly due to decreased expression of miRNA-125a and 125b in embryonic stem cells. Despite its cytoplasmic localisation, p53 is degraded in 26S proteasomes in embryonic stem cells. This process is controlled by Mdm2, the deubiquitinating enzyme Hausp and Ubc13. In contrast, the E3 ligase PirH2 appears to be less important for the control of p53 in embryonic stem cells. During differentiation, p53 protein and RNA levels are decreased which corresponds to increased expression of miRNA-125a and miRNA-125b.     

Expression and distribution of JNK/SAPK-associated scaffold protein JSAP1 in developing and adult mouse brain

The c-Jun N-terminal kinase (JNK) is one of the three major mitogen-activated protein kinases (MAPKs) playing key roles in various cellular processes in response to both extracellular and intracellular stimuli. JNK/SAPK-associated protein 1 (JSAP1 also referred to as JIP3) is a JNK-associated scaffold that controls the specificity and efficiency of JNK signaling cascades. Here we studied its expression in mouse brains. JSAP1 mRNA was expressed in developing and adult brains, showing spatial patterns similar to JNK1-3 mRNAs. In embryos, JSAP1 immunolabeling was intense for progenitor cells in the ventricular zone throughout the brain and in the external granular layer of the cerebellum, and for neurons and glial cells differentiating in the mantle zone. In adults, JSAP1 was distributed in various neurons and Bergmann glia, with higher levels in striatal cholinergic interneurons, telencephalic parvalbumin-positive interneurons and cerebellar Purkinje cells. In these neurons, JSAP1 was observed as tiny particulate staining in spines, dendrites, perikarya and axons, where it was often associated with the smooth endoplasmic reticulum (sER) and cell membrane. Immunoblots revealed enriched distribution in the microsomal fraction and cytosolic fraction. Therefore, the characteristic cellular expression and subcellular distribution of JSAP1 might be beneficial for cells to efficiently link external stimuli to the JNK MAPK pathway and other intracellular machineries.     

In vitro development of mouse embryonic stem cells lacking JNK/stress-activated protein kinase-associated protein 1 (JSAP1) scaffold protein revealed its requirement during early embryonic neurogenesis

The Jsap1 gene encodes a scaffold protein for c-Jun N-terminal kinase cascades. We established c-Jun N-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1)-null mouse embryonic stem cell lines by homologous recombination. The JSAP1-null embryonic stem cells were viable, however, exhibited hyperplasia of the ectoderm during embryoid body formation, and spontaneously differentiated into neurons more efficiently than did wild type. The expression of components of c-Jun N-terminal kinase cascades and a subset of marker mRNAs during early embryogenesis was altered in the JSAP1-null mutants. Retinoic acid dramatically increased the expression of JSAP1 and JNK3, which were co-precipitated with anti-JNK3 in the neuroectoderm of wild type but not JSAP1-null embryoid bodies. In the neurons differentiated from the wild type embryoid bodies, JSAP1 was localized in the soma, neurites, and growth cone-like structure of the neurites, and neurite outgrowth from the JSAP1-null embryoid bodies was apparently less efficient than from wild type. JSAP1 and c-Jun N-terminal kinase 3 were coexpressed in the embryonic ectoderm of E7.5 mouse embryo, whereas Wnt1 and Pax2 were coexpressed with JSAP1 at the midbrain-hindbrain junction in E12.5 mouse embryo, thus suggesting that JSAP1 is required for early embryonic neurogenesis.     

Non-invasive label-free monitoring the cardiac differentiation of human embryonic stem cells in-vitro by Raman spectroscopy

Background

Online label-free monitoring of in-vitro differentiation of stem cells remains a major challenge in stem cell research. In this paper we report the use of Raman micro-spectroscopy (RMS) to measure time- and spatially-resolved molecular changes in intact embryoid bodies (EBs) during in-vitro cardiogenic differentiation.

Methods

EBs formed by aggregation of human embryonic stem cells (hESCs) were cultured in defined medium to induce differentiation towards cardiac phenotype and maintained in purpose-built micro-bioreactors on the Raman microscope for 5 days (between days 5 and 9 of differentiation) and spatially-resolved spectra were recorded at 24 h intervals.

Results

The Raman spectra showed that the onset of spontaneous beating of EBs at day 7 coincided with an increase in the intensity of the Raman bands at 1340 cm^− 1, 1083 cm^− 1, 937 cm^− 1, 858 cm^− 1, 577 cm^− 1 and 482 cm^− 1. The spectral maps corresponding to these bands had a high positive correlation with the expression of the cardiac-specific α-actinin obtained by immuno-fluorescence imaging of the same EBs. The spectral markers obtained here are also in agreement with previous studies performed on individual live hESC-derived CMs.

Conclusions

The intensity profile of these Raman bands can be used for label-free in-situ monitoring of EBs to estimate the efficacy of cardiogenic differentiation.

General significance

As the acquisition of the time-course Raman spectra did not affect the viability or the differentiation potential of the hESCs, this study demonstrates the feasibility of using RMS for on-line non-invasive continuous monitoring of such processes inside bioreactor culture systems.     

Assessment of drug induced developmental toxicity using human embryonic stem cells

Embryonic stem (ES) cells are unique as they have the potential to be generated in large numbers and the ability to differentiate into the three germ layers via embryoid body (EB) formation. This property could be utilized as an index to study initial mammalian development. We have investigated the utility of a comprehensively characterized human ES (hES) cell line (ReliCellhES1) for testing the embryotoxic effects of compounds using cytotoxicity assays. Further, we performed real time gene expression analysis to check the alterations in germ layer markers expression upon drug treatment. The results show that assays using hES cells could serve as a reliable, sensitive and robust method to assess embryotoxic potential of compounds. They also provide a proof of concept that hES cells can be used as an in vitro model to demonstrate developmental toxicity, and to examine the germ layer-specific effects on differentiating EBs.     

DNA羟甲基化在小鼠胚胎干细胞中的研究进展

简要总结DNA羟甲基化在小鼠胚胎干细胞(mouse embryonic stem cells,mESC)中的最新研究进展.DNA甲基化(DNAmethylation)影响染色质的结构与功能,在发育与疾病发生过程中具有重要作用.2009年Tahiliani等发现TET1可以催化甲基化胞嘧啶(5-methylcytosine,5mC)氧化为羟甲基化胞嘧啶(5-hydroxymethylcytosine,5hmC).DNA羟甲基化(DNAhydroxymethylation)被认为是调节DNA甲基化的一种重要方式,成为了表观遗传学的研究热点之一.     

人胚胎干细胞传代培养及细胞化学染色特性

目的 体外建立人胚胎干细胞传代培养方法,研究人胚胎干细胞细胞化学染色特性.方法 以小鼠胚胎成纤维细胞作为饲养层传代培养人胚胎干细胞,检测人胚胎干细胞、自发分化克隆及拟胚体的细胞化学染色特性.结果 人胚胎干细胞在小鼠胚胎成纤维细胞饲养层上传30代以上其形态保持不变;人胚胎十细胞碱性磷酸酶、过碘酸-雪夫反应、α-醋酸萘酚酯酶染色阳性,自发分化克隆细胞阳性程度明显减弱;人胚胎干细胞形成的拟胚体碱性磷酸酶染色弱阳性,过碘酸-雪夫反应、α-醋酸萘酚酯酶染色阳性.结论 小鼠胚胎成纤维细胞能支持人胚胎干细胞传代培养,细胞化学染色结果能初步鉴别人胚胎干细胞未分化特性.     

Involvement of Ras in extraembryonic endoderm differentiation of embryonic stem cells

Embryonic stem (ES) cells, derived from the inner cell mass of blastocyst can differentiate into multiple cell lineages. In this study, we examined the possible involvement of Ras in ES cell differentiation. We found that Ras was activated upon formation of embryoid bodies (EBs), an initial step in ES cell differentiation. When expressed during EB differentiation, a dominant-negative mutant of Ras suppressed induction of marker genes for extraembryonic endoderm differentiation, including GATA-4, GATA-6, alpha-fetoprotein, and hepatocyte nuclear factor 3beta, while an activated mutant promoted their induction. Expression of a Ras mutant that selectively activates the Raf/MEK/Erk pathway also enhanced induction of extraembryonic endoderm markers, and treatment with a MEK inhibitor resulted in their decreased expression. In addition, Ras stimulated downregulation of Nanog, a suppressor of endoderm differentiation in ES cells. These data suggest that Ras activation during EB differentiation plays a crucial role in initiation of extraembryonic endoderm differentiation.     

Cluster characterization of mouse embryonic stem cell-derived pluripotent embryoid bodies in four distinct developmental stages

The formation of embryoid bodies (EBs) is the principal step in the differentiation of embryonic stem (ES) cells. In this study, the morphological characteristics and gene expression patterns of EBs related to the sequential stages of embryonic development were well defined in four distinct developmental groups over 112 days of culture: early-stage EBs groups (1–7 days of differentiation), mid-stage EBs groups (9–15 days of differentiation), maturing EBs groups (17–45 days of differentiation) and matured EBs groups (50 days of differentiation). We first determined definite histological location of apoptosis within EBs and the sequential expression of molecular markers representing stem cells (Oct4, SSEA-1, Sox-2 and AKP), germ cells (Fragilis, Dazl, c-kit, StellaR, Mvh and Stra8), ectoderm (Neurod, Nestin and Neurofilament), mesoderm (Gata-1, Flk-1 and Hbb) and endoderm (AFP and Transthyretin). Our results revealed that developing EBs possess either pluripotent stem cell or germ cell states and that three-dimensional aggregates of EBs initiate mES cell differentiation during prolonged culture in vitro. Therefore, we suggest that this EB system to some extent recapitulates the early developmental processes occurring in vivo.     

Embryoid body formation from embryonic and induced pluripotent stem cells: Benefits of bioreactors

Embryonic stem (ES) cells have the ability to differentiate into all germ layers, holding great promise not only for a model of early embryonic development but also for a robust cell source for cell-replacement therapies and for drug screening. Embryoid body (EB) formation from ES cells is a common method for producing different cell lineages for further applications. However, conventional techniques such as hanging drop or static suspension culture are either inherently incapable of large scale production or exhibit limited control over cell aggregation during EB formation and subsequent EB aggregation. For standardized mass EB production, a well defined scale-up platform is necessary. Recently, novel scenario methods of EB formation in hydrodynamic conditions created by bioreactor culture systems using stirred suspension systems (spinner flasks), rotating cell culture system and rotary orbital culture have allowed large-scale EB formation. Their use allows for continuous monitoring and control of the physical and chemical environment which is difficult to achieve by traditional methods. This review summarizes the current state of production of EBs derived from pluripotent cells in various culture systems. Furthermore, an overview of high quality EB formation strategies coupled with systems for in vitro differentiation into various cell types to be applied in cell replacement therapy is provided in this review. Recently, new insights in induced pluripotent stem (iPS) cell technology showed that differentiation and lineage commitment are not irreversible processes and this has opened new avenues in stem cell research. These cells are equivalent to ES cells in terms of both self-renewal and differentiation capacity. Hence, culture systems for expansion and differentiation of iPS cells can also apply methodologies developed with ES cells, although direct evidence of their use for iPS cells is still limited.     

Transforming growth factor-beta2 enhances differentiation of cardiac myocytes from embryonic stem cells

Stem cell therapy holds great promise for the treatment of injured myocardium, but is challenged by a limited supply of appropriate cells. Three different isoforms of transforming growth factor-beta (TGF-beta) -beta1, -beta2, and -beta3 exhibit distinct regulatory effects on cell growth, differentiation, and migration during embryonic development. We compared the effects of these three different isoforms on cardiomyocyte differentiation from embryonic stem (ES) cells. In contrast to TGF-beta1, or -beta3, treatment of mouse ES cells with TGF-beta2 isoform significantly increased embryoid body (EB) proliferation as well as the extent of the EB outgrowth that beat rhythmically. At 17 days, 49% of the EBs treated with TGF-beta2 exhibited spontaneous beating compared with 15% in controls. Cardiac myocyte specific protein markers sarcomeric myosin and alpha-actin were demonstrated in beating EBs and cells isolated from EBs. In conclusion, TGF-beta2 but not TGF-beta1, or -beta3 promotes cardiac myocyte differentiation from ES cells.     

Enhancement by growth factors of cardiac myocyte differentiation from embryonic stem cells: a promising foundation for cardiac regeneration

Cell transplantation is a promising, still novel, potentially therapeutic approach for the treatment of heart diseases. Clinical applications require generation of large number of donor cells. Embryonic stem (ES) cells are capable of self-renewal apparently in an unlimited fashion, in vitro. Theoretically, they can differentiate into any cell type required for cell transplantation, including cardiac myocytes. Diverse growth factors have been implicated in programming diverse cellular processes, including development of the embryonic heart, ES cell self-renewal, and cardiac myocyte differentiation from ES cells. This review addresses the current understanding of the role of growth factors in the differentiation of cardiac myocytes from ES-embryoid body cell systems in vitro as well as cardiac regeneration in vivo.     

Differentiation and characterization of embryonic stem cells into three germ layers

Embryonic stem cells differentiated on M15 cells have previously been shown to give rise to cells of the mesendodermal and definitive endodermal lineages. Here we demonstrate that neuroectodermal and mesodermal lineages can be derived from ES cells cultured on M15 cells and subsequently subjected to specific culture conditions, as confirmed by the expression of molecular markers. Prospective isolation and microarray analyses showed that neuroectodermal cells expressed anterior-to-posterior, as well as dorso-ventral regional markers, suggesting that this procedure could be used for the induction of cells belonging to a wide variety of neural lineages. Lateral mesoderm and paraxial mesoderm cells were also produced and their gene expression profiles were confirmed by microarray analyses. These results indicate that the M15 cell system provides a valuable tool for generating ES cell-derived lineage-specific cell types belonging to the three germ layers, namely neuroectoderm, mesoderm, and definitive endoderm.     

The reversal of hyperglycemia after transplantation of mouse embryonic stem cells induced into early hepatocyte-like cells in streptozotocin-induced diabetic mice

Cellular replacement therapy is a potential therapeutic strategy for diabetes. In this study, we investigated the effect of transplantation of induced mouse embryonic stem cells (mESCs) into endoderm and early hepatocyte-like cells in streptozotocin (STZ)-diabetic mice. After embryoid body (EB) formation from mESC, the EBs were cultured in the presence of dexamethasone (DEX) and insulin for 4 days then was added acidic fibroblast growth factor (aFGF), hepatocyte growth factor (HGF) and oncostatin M (OSM) for 10 days, respectively. Blood glucose levels, intraperitoneal glucose tolerance (IGT) test and islet histology were assessed. The result revealed that transplantation of induced mESCs into early hepatocyte-like cells could repair pancreatic islets of control group. Blood glucose levels and intraperitoneal glucose tolerance test were significantly improved in test group compared to control group. Furthermore, there was significant increase in the number of islets in test group compared to control group. The findings declare that induced mESCs into endoderm and early hepatocyte-like cells, are appropriate candidate for regenerative therapy of pancreatic islets in type I diabetes.     

Pluripotent differentiation in vitro of murine Es-D3 embryonic stem cells

Although the ES-D3 murine embryonic stem cell line was one of the first derived, little information exists on the in vitro differentiation potential of these cells. We have used immunocytochemical and flow cytometric methods to monitor ES-D3 embryoid body differentiation in vitro during a 21-d period. Spontaneous differentiation of embryoid body cells was induced by leukemia inhibitory factor withdrawal in the absence of feeder cells. The pluripotent stem cell markers Oct-3/4, SSEA-1, and EMA-1 were found to persist for at least 7 d, whereas the primitive endoderm marker cytokeratin endo-A was expressed at increasing levels from day 6. The localization of these antigens within the embryoid bodies suggested that embryonic ectoderm- and primitive endoderm-derived tissues were segregated. Localized expression of class III beta-tubulin and sarcomeric myosin also was detected, indicating that representatives of all three embryonic germ layers were present after induction of differentiation in vitro.     

Decreased surfactant protein B expression in mice derived completely from embryonic stem cells

ES mice that are derived completely from embryonic stem (ES) cells can be obtained by tetraploid embryo complementation. Many neonate ES mice die because of respiratory distress, but it is not clear what contributes to the phenomenon. Using five microsatellite DNA markers, we confirmed that our ES mice were completely derived from ES cells and contained no tetraploid component. The neonatal ES mice that exhibited respiratory distress were tested for surfactant protein B (SP-B) expression by Western blotting. These mice had no SP-B expression, and even apparently healthy adult ES mice had decreased SP-B levels and aberrant SP-B phenotypes. These data suggest that the expression of SP-B protein is an important factor in the survival of ES mice to term and adulthood.