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Alzheimer's disease (AD), a common neurodegenerative disorder associated with gradually to dramatic neuronal death, synaptic loss and dementia, is considered to be one of the most obscure and intractable brain disorders in medicine. Currently, there is no therapy clinically available to induce marked symptomatic relief in AD patients. In recent years, the proof-of-concept studies using stem cell-based approaches in transgenic AD animal models provide new hope to develop stem cell-based therapies for the effective treatment of AD. The degeneration of basal forebrain cholinergic neurons (BFCNs) and the resultant cholinergic abnormalities in the brain contribute substantially to the cognitive decline of AD patients. The approaches using stem cell-derived BFCNs as donor cells need to be developed, and to provide proof of principle that this subtype-specific neurons can induce functional recovery of AD animal models. With the continuous scientific advances in both academic and industrial fields, the potentials of stem cells in cellular neuroprotection and cell replacement in vivo have been elucidated, and stem cell-based therapy for repairing degenerative brains of AD is promising. [ABSTRACT FROM AUTHOR]

The hippocampus executes crucial functions from declarative memory to adaptive behaviors associated with cognition and emotion. However, the mechanisms of how morphogenesis and functions along the hippocampal dorsoventral axis are differentiated and integrated are still largely unclear. Here, we show that Nr2f1 and Nr2f2 genes are distinctively expressed in the dorsal and ventral hippocampus, respectively. The loss of Nr2f2 results in ectopic CA1/CA3 domains in the ventral hippocampus. The deficiency of Nr2f1 leads to the failed specification of dorsal CA1, among which there are place cells. The deletion of both Nr2f genes causes almost agenesis of the hippocampus with abnormalities of trisynaptic circuit and adult neurogenesis. Moreover, Nr2f1/2 may cooperate to guarantee appropriate morphogenesis and function of the hippocampus by regulating the Lhx5-Lhx2 axis. Our findings revealed a novel mechanism that Nr2f1 and Nr2f2 converge to govern the differentiation and integration of distinct characteristics of the hippocampus in mice. [ABSTRACT FROM AUTHOR]

During embryonic development, tissue-specific transcription factors and chromatin remodelers function together to ensure gradual, coordinated differentiation of multiple lineages. Here, we define this regulatory interplay in the developing retinal pigmented epithelium (RPE), a neuroectodermal lineage essential for the development, function and maintenance of the adjacent retina. We present a highresolution spatial transcriptomic atlas of the developing mouse RPE and the adjacent ocular mesenchyme obtained by geographical position sequencing (Geo-seq) of a single developmental stage of the eye that encompasses young and more mature ocular progenitors. These transcriptomic data, available online, reveal the key transcription factors and their gene regulatory networks during RPE and ocular mesenchyme differentiation. Moreover, conditional inactivation followed by Geo-seq revealed that this differentiation program is dependent on the activity of SWI/SNF complexes, shown here to control the expression and activity of RPE transcription factors and, at the same time, inhibit neural progenitor and cell proliferation genes. The findings reveal the roles of the SWI/SNF complexes in controlling the intersection between RPE and neural cell fates and the coupling of cell-cycle exit and differentiation. [ABSTRACT FROM AUTHOR]

Establishment of progenitor cell populations and lineage diversity during embryogenesis and the differentiation of pluripotent stem cells is a fascinating and intricate biological process. Conceptually, an understanding of this developmental process provides a framework to integrate stem-cell pluripotency, cell competence and differentiating potential with the activity of extrinsic and intrinsic molecular determinants. The recent advent of enabling technologies of high-resolution transcriptome analysis at the cellular, population and spatial levels proffers the capability of gaining deeper insights into the attributes of the gene regulatory network and molecular signaling in lineage specification and differentiation. In this review, we provide a snapshot of the emerging enabling genomic technologies that contribute to the study of development and stem-cell biology. [ABSTRACT FROM AUTHOR]

Vascular establishment is one of the early events in embryogenesis. It is believed that vessel-initiating endothelial progenitors cluster to form the first primitive vessel. Understanding the molecular identity of these progenitors is crucial in order to elucidate lineage hierarchy. In this study, we identify protein C receptor (Procr) as an endothelial progenitor marker and investigate the role of Procr+ progenitors during embryonic vascular development. Using a ProcrmGFP-2A-lacZ reporter, we reveal a much earlier Procr expression (embryonic day 7.5) than previously acknowledged (embryonic day 13.5). Genetic fate-mapping experiments using ProcrCre and ProcrCreER demonstrate that Procr+ cells give rise to blood vessels throughout the entire embryo proper. Single-cell RNA-sequencing analyses place Procr+ cells at the start of endothelial commitment and maturation. Furthermore, targeted ablation of Procr+ cells results in failure of vessel formation and early embryonic lethality. Notably, genetic fate mapping and scRNA-seq pseudotime analysis support the view that Procr+ progenitors can give rise to hemogenic endothelium. In this study, we establish a Procr expression timeline and identify Procr+ vessel-initiating progenitors, and demonstrate their indispensable role in establishment of the vasculature during embryo development. [ABSTRACT FROM AUTHOR]

The article presents a study which identified the key cytokines favoring traumatic brain injury (TBI) and found that patients with TBI with a better outcome increased concentrations of macrophage colony-stimulating factor. Topics include major sources to produce interleukin-6 and transforming growth factor-Β (M6T), findings on M6T treatment, and how M6T treatment might repair TBI.

Proper neural commitment is essential for ensuring the appropriate development of the human brain and for preventing neurodevelopmental diseases such as autism spectrum disorders, schizophrenia, and intellectual disorders. However, the molecular mechanisms underlying the neural commitment in humans remain elusive. Here, we report the establishment of a neural differentiation system based on human embryonic stem cells (hESCs) and on comprehensive RNA sequencing analysis of transcriptome dynamics during early hESC differentiation. Using weighted gene co-expression network analysis, we reveal that the hESC neurodevelopmental trajectory has five stages: pluripotency (day 0); differentiation initiation (days 2, 4, and 6); neural commitment (days 8-10); neural progenitor cell proliferation (days 12, 14, and 16); and neuronal differentiation (days 18, 20, and 22). These stages were characterized by unique module genes, which may recapitulate the early human cortical development. Moreover, a comparison of our RNA-sequencing data with several other transcriptome profiling datasets from mice and humans indicated that Module 3 associated with the day 8-10 stage is a critical window of fate switch from the pluripotency to the neural lineage. Interestingly, at this stage, no key extrinsic signals were activated. In contrast, using CRISPR/ Cas9-mediated gene knockouts, we also found that intrinsic hub transcription factors, including the schizophrenia-associated SIX3 gene and septo-optic dysplasia-related HESX1 gene, are required to program hESC neural determination. Our results improve the understanding of the mechanism of neural commitment in the human brain and may help elucidate the etiology of human mental disorders and advance therapies for managing these conditions. [ABSTRACT FROM AUTHOR]

Mouse pluripotent cells, such as embryonic stem cells (ESCs) and epiblast stem cells (EpiSCs), provide excellent in vitro systems to study imperative pre- and postimplantation events of in vivo mammalian development. It is known that mouse ESCs are dynamic heterogeneous populations. However, it remains largely unclear whether and how EpiSCs possess heterogeneity and plasticity similar to that of ESCs. Here, we show that EpiSCs are discriminated by the expression of a specific marker T (Brachyury) into two populations. The T-positive (T+) and the T-negative (T-) populations can be interconverted within the same culture condition. In addition, the two populations display distinct responses to bone morphogenetic protein (BMP) signaling and different developmental potentials. The T- EpiSCs are preferentially differentiated into ectoderm lineages, whereas T+ EpiSCs have a biased potential for mesendoderm fates. Mechanistic studies reveal that T+ EpiSCs have an earlier and faster response to BMP4 stimulation than T- EpiSCs. Id1 mediates the commitment of T- EpiSCs to epidermal lineage during BMP4 treatment. On the other hand, Snail modulates the conversion ofT+ EpiSCs to mesendoderm fates with the presence of BMP4. Furthermore, T expression is essential for epithelialmesenchymal transition during EpiSCs differentiation. Our findings suggest that the dynamic heterogeneity of the T+/T- subpopulation primes EpiSCs toward particular cell lineages, providing important insights into the dynamic development of the early mouse embryo. [ABSTRACT FROM AUTHOR]

Mouse pluripotent stem cells (PSCs), such as ES cells and induced PSCs (iPSCs), are an excellent system to investigate the molecular and cellular mechanisms involved in early embryonic development. The signaling pathways orchestrated by leukemia inhibitor factor/STAT3, Wnt/β-catenin, and FGF/MEK/ERK play key roles in the generation of pluripotency. However, the function of TGF-β signaling in this process remains elusive. Here we show that inhibiting TGF-β signaling with its inhibitor SB431542 can substitute for Oct4 during reprogramming. Moreover, inhibiting TGF-β signaling can sustain the pluripotency of iPSCs and ES cells through modulating FGF/MEK/ERK signaling. Therefore, this study reveals a novel function of TGF-β signaling inhibition in the generation and maintenance of PSCs. [ABSTRACT FROM AUTHOR]

Unraveling the mechanisms underlying early neural differentiation of embryonic stem cells (ESCs) is crucial to developing cell-based therapies of neurodegenerative diseases. Neural fate acquisition is proposed to be controlled by a 'default' mechanism, for which the molecular regulation is not well understood. In this study, we investigated the functional roles of Mediator Med23 in pluripotency and lineage commitment of murine ESCs. Unexpectedly, we found that, despite the largely unchanged pluripotency and self-renewal of ESCs, Med23 depletion rendered the cells prone to neural differentiation in different differentiation assays. Knockdown of two other Mediator subunits, Med1 and Med15, did not alter the neural differentiation of ESCs. Med15 knockdown selectively inhibited endoderm differentiation, suggesting the specificity of cell fate control by distinctive Mediator subunits. Gene profiling revealed that Med23 depletion attenuated BMP signaling in ESCs. Mechanistically, MED23 modulated Bmp4 expression by controlling the activity of ETS1, which is involved in Bmp4 promoter-enhancer communication. Interestingly, med23 knockdown in zebrafish embryos also enhanced neural development at early embryogenesis, which could be reversed by co-injection of bmp4 mRNA. Taken together, our study reveals an intrinsic, restrictive role of MED23 in early neural development, thus providing new molecular insights for neural fate determination. [ABSTRACT FROM AUTHOR]

Early neurodevelopment requires cell fate commitment from pluripotent stem cells to restricted neural lineages, which involves the epigenetic regulation of chromatin structure and lineage-specific gene transcription. However, it remains unclear how histone H3 lysine 9 acetylation (H3K9Ac), an epigenetic mark representing transcriptionally active chromatin, is involved in the neural commitment from pluripotent embryonic stem cells (ESCs). In this study, we demonstrate that H3K9Ac gradually declines during the first 4 days of in vitro neural differentiation of human ESCs (hESCs) and then increases during days 4-8. Consistent with this finding, the H3K9Ac enrichment at several pluripotency genes was decreased, and H3K9Ac occupancies at the loci of neurodevelop-mental genes increased during hESC neural commitment. Inhibiting H3K9 deacetylation on days 0 - 4 by histone deacetylase inhibitors (HDACis) promoted hESC pluripotency and suppressed its neural differentiation. Conversely, HDACi-elicited up-regulation of H3K9 acetylation on days 4-8 enhanced neural differentiation and activated multiple neurodevelopmental genes. Mechanistically, HDACis promote pluripotency gene transcription to support hESC self-renewal through suppressing HDAC3 activity. During hESC neural commitment, HDACis relieve the inhibitory activities of HDAC1/5/8 and thereby promote early neurodevelopmental gene expression by interfering with gene-specific histone acetylation patterns. Furthermore, p300 is primarily identified as the major histone acetyltransferase involved in both hESC pluripotency and neural differentiation. Our results indicate that epigenetic modification plays pivotal roles during the early neural specification of hESCs. The histone acetylation, which is regulated by distinct HDAC members at different neurodevelopmental stages, plays dual roles in hESC pluripotency maintenance and neural differentiation. [ABSTRACT FROM AUTHOR]

Ectoderm is one of the three classic germ layers in the early mouse embryo, with the capacity to develop into both the central nervous system and epidermis. Because it is a transient phase of development with few molecular markers, the early ectoderm is the least understood germ layer in mouse embryonic development. In this work, we studied the differentiation potential of isolated ectoderm tissue in response to BMP signaling at various developmental stages (E6.5, E7.0 and E7.5), and identified a transient region in the anteriorproximal side of the embryo at E7.0 that possesses the ability to become neural or epidermal ectoderm in response to the absence or presence of BMP4, respectively. Furthermore, we demonstrated that inhibition of Nodal signaling could direct the pluripotent E6.5 epiblast cells towards ectoderm lineages during differentiation in explants in vitro. Our work not only improves our understanding of ectodermal layer development in early embryos, but also provides a framework for regenerative differentiation towards ectodermal tissues. [ABSTRACT FROM AUTHOR]

During early embryonic development, bone morphogenetic protein (BMP) signaling is essential for neural/non-neural cell fate decisions. BMP signaling inhibits precocious neural differentiation and allows for proper differentiation of mesoderm, endoderm, and epidermis. However, the mechanisms underlying theBMPpathway-mediated cell fate decision remain largely unknown. Here, we show that the expression of Ovol2, which encodes an evolutionarily conserved zinc finger transcription factor, is down-regulated during neural differentiation of mouse embryonic stem cells. Knockdown of Ovol2 in embryonic stem cells facilitates neural conversion and inhibits mesendodermal differentiation, whereas Ovol2 overexpression gives rise to the opposite phenotype. Moreover, Ovol2 knockdown partially rescues the neural inhibition and mesendodermal induction by BMP4. Mechanistic studies further show that BMP4 directly regulates Ovol2 expression through the binding of Smad1/5/8 to the second intron of the Ovol2 gene. In the chick embryo, cOvol2 expression is specifically excluded from neural territory and is up-regulated by BMP4. In addition, ectopic expression of cOvol2 in the prospective neural plate represses the expression of the definitive neural plate marker cSox2. Taken together, these results indicate that Ovol2 acts downstream of the BMP pathway in the cell fate decision between neuroectoderm and mesendoderm to ensure proper germ layer development. [ABSTRACT FROM AUTHOR]

The Ca2+ signaling pathway appears to regulate the processes of the early development through its antagonism of canonical Wnt/β-catenin signaling pathway. However, the underlying mechanism is still poorly understood. Here, we show that nuclear factor of activated T cells (NFAT), a component of Ca2+ signaling, interacts directly with Dishevelled (Dvl) in a Ca2+-dependent manner. A dominant negative form of NFAT rescued the inhibition of the Wnt/β-catenin pathway triggered by the Ca2+ signal. NFAT functioned downstream of β-catenin without interfering with its stability, but influencing the interaction of β-catenin with Dvl by its competitively binding to Dvl. Furthermore, we demonstrate that NFAT is a regulator in the proliferation and differentiation of neural progenitor cells by modulating canonical Wnt/β-catenin signaling pathway in the neural tube of chick embryo. Our findings suggest that NFAT negatively regulates canonical Wnt/β-catenin signaling by binding to Dvl, thereby participating in vertebrate neurogenesis. [ABSTRACT FROM AUTHOR]

Proliferation of the neural/neuronal progenitor cells (NPCs) at the ventricular zone of the dorsal spinal cord requires the stimuli of Wnt and bone morphogenic protein (BMP). However, how these two signaling pathways are regulated to initiate differentiation in the NPCs as they enter the intermediate zone is not known. Here, we show that Smad6, a negative regulator of BMP signaling, is expressed in the intermediate zone of the chick dorsal spinal cord. Knockdown experiments show that Smad6 is required for promoting NPCs to exit the cell cycle and differentiate into neurons. Although we find that Smad6 inhibits BMP signaling, as expected, we also find that Smad6 unexpectedly inhibits the Wnt/β-catenin pathway. The inhibition of the Wnt/β-catenin pathway by Smad6 is independent of its effect on the BMP pathway. Rather, Smad6 through its N-terminal domain and link region enhances the interaction of C-terminal binding protein with the β-catenin/T cell factor (TCF) complex and the TCF-binding element to inhibit β-catenin-mediated transcriptional activation. Our study provides evidence that transition of NPCs from a proliferative state to a differentiating state is controlled by the dual inhibitory role of Smad6 to both BMP and Wnt signaling at the level of transcription. [ABSTRACT FROM AUTHOR]

Accumulation of senile plaques composed of amyloid β-peptide (Aβ) is a pathological hallmark of Alzheimer disease (AD), and Aβ is generated through the sequential cleavage of amyloid precursor protein (APP) by β- and γ-secretase. Although oxidative stress has been implicated in the AD pathogenesis by inducing Aβ production, the underlying mechanism remains elusive. Here we show that the pro-oxidant H2O2 promotes Aβ production through c-Jun N-terminal kinase (JNK)-dependent activation of γ-secretase. Treatment with H2O2 induced significant increase in the levels of intracellular and secreted Aβ in human neuroblastoma SH-SY5Y cells. Although γ-secretase-mediated cleavage of APP or C99 was enhanced upon H2O2 treatment, expression of APP or its α/β-secretase-mediated cleavage was not affected. Silencing of the stress-activated JNK by small interfering RNA or the specific JNK inhibitor SP600125 reduced H2O2-induced γ-secretase-mediated cleavage of APP. JNK activity was augmented in human brain tissues from AD patients and active JNK located surrounding the senile plaques in the brain of AD model mouse. Our data suggest that oxidative stress-activated JNK may contribute to senile plaque expansion through the promotion of γ-secretase-mediated APP cleavage and Aβ production. [ABSTRACT FROM AUTHOR]

Abstract  ADAM23, belonging to ADAM (A Disintegrin And Metalloprotease) protein family, is mainly expressed in brain. P19 cells could differentiate into neuroectodermal cell lineage after cell aggregates have been induced by retinoic acid (RA). In this report, we show that the post-transcriptional and post-translational processes of ADAM23 are regulated during the differentiation of P19 cells. In P19-derived neurons, ADAM23 is polarized distributed in the proximal part. To explore the possible roles of ADAM23 during P19 cell neuronal differentiation, ADAM23-RNAi P19 cell lines were established. These transfected cells could differentiate into neurofilament-expression neurons in the absence of RA, whereas wild-type P19 cell can not. These results suggest ADAM23 may play roles in both early and later stage of neuronal differentiation. [ABSTRACT FROM AUTHOR]

Wnt/β-catenin signaling plays a critical role in embryonic myogenesis. Here we show that in P19 embryonic carcinoma stem cells, Wnt/β-catenin signaling initiates the myogenic process depends on β-catenin-mediated relief of I-mfa (inhibitor of MyoD Family a) suppression of myogenic regulatory factors (MRFs). We found that β-catenin interacted with I-mfa and that the interaction was enhanced by Wnt3a. In addition, we found that the interaction between β-catenin and I-mfa was able to attenuate the interaction of I-mfa with MRFs, relieve I-mfa-mediated suppression of the transcriptional activity and cytosolic sequestration of MRFs, and initiate myogenesis in a P19 myogenic model system that expresses exogenous myogenin. This work reveals a mechanism for the regulation of MRFs during myogenesis by elucidating a β-catenin-mediated, but lymphoid enhancing factor-1/T cell factor independent, mechanism in regulation of myogenic fate specification and differentiation of P19 mouse stem cells. [ABSTRACT FROM AUTHOR]

Mitosin/CENP-F is a human nuclear matrix protein with multiple leucine zipper motifs. Its accumulation in S-G2 phases and transient kinetochore localization in mitosis suggest a multifunctional protein for cell proliferation. Moreover, its murine and avian orthologs are implicated in myocyte differentiation. Here we report its interaction with activating transcription factor-4 (ATF4), a ubiquitous basic leucine zipper transcription factor important for proliferation, differentiation, and stress response. The C-terminal portion of mitosin between residues 2488 and 3113 bound to ATF4 through two distinct domains, one of which was a leucine zipper motif. Mitosin mutants containing these domains were able to either supershift or disrupt the ATF4-DNA complex. On the other hand, ATF4, but not ATF1-3 or ATF6, interacted with mitosin through a region containing the basic leucine zipper motif. Moreover, overexpression of full-length mitosin repressed the transactivation activity of ATF4 in dual luciferase-based reporter assays, while knocking down mitosin expression manifested the opposite effects. These findings suggest mitosin to be a negative regulator of ATF4 in interphase through direct interaction. [ABSTRACT FROM AUTHOR]

Bone morphogenetic protein (BMP) signaling plays a crucial role in maintaining the pluripotency of mouse embryonic stem cells (ESCs) and has negative effects on ESC neural differentiation. However, it remains unclear when and how BMP signaling executes those different functions during neural commitment. Here, we show that a BMP4-sensitive window exists during ESC neural differentiation. Cells at this specific period correspond to the egg cylinder stage epiblast and can be maintained as ESC-derived epiblast stem cells (ESD-EpiSCs), which have the same characteristics as EpiSCs derived from mouse embryos. We propose that ESC neural differentiation occurs in two stages: first from ESCs to ESD-EpiSCs and then from ESD-EpiSCs to neural precursor cells (NPCs). We further show that BMP4 inhibits the conversion of ESCs into ESD-EpiSCs during the first stage, and suppresses ESD-EpiSC neural commitment and promotes non-neural lineage differentiation during the second stage. Mechanistic studies show that BMP4 inhibits FGF/ERK activity at the first stage but not at the second stage; and IDs, as important downstream genes of BMP signaling, partially substitute for BMP4 functions at both stages. We conclude that BMP signaling has distinct functions during different stages of ESC neural commitment. [ABSTRACT FROM AUTHOR]

Heparan sulfate proteoglycans (HSPGs) are required for various signaling pathways, one of which is the bone morphogenetic protein (BMP) signaling pathway. N-deacetylase/N-sulfotransferase-1 (NDST1) participates in synthesizing heparan sulfate (HS) chains of HSPGs, and is involved in bone and lung development. Here, we report that in spite of the redundant expression of Ndst2, Ndst3 and Ndst4 genes, Ndst1-/- mice display defective differentiation of lung cells and increased cell proliferation. Loss of Ndst1 in the lung enhances downstream BMP signaling in vivo. Noggin, which is an antagonist of BMP, can rescue the Ndst1-/- lung morphogenetic defects in explant cultures. Further studies in vitro indicated that loss of Ndst1 significantly impairs BMP internalization by decreasing BMP binding to endogenous HS. Exogenous heparin can rescue both the BMP signaling and BMP internalization abnormalities in Ndst1-/- lung. Thus, we propose that HS regulates BMP signaling by controlling the balance between BMP binding to HS, and that BMP receptors and NDST1-dependent modification are essential for this process. The results suggest that NDST1-dependent HS is essential for proper functioning of BMP in embryonic lung development. [ABSTRACT FROM AUTHOR]