Development Of Glia Research Articles

Meteorin promotes the formation of GFAP-positive glia via activation of the Jak-STAT3 pathway

Meteorin is an orphan ligand which has been previously reported to control neuritogenesis and angiogenesis, as well as gliogenesis. However, the precise function of this factor in CNS development and the underlying molecular mechanisms are poorly understood. Here, we demonstrate that meteorin is involved in GFAP-positive glial differentiation through activation of the Jak-STAT3 pathway, by using neurosphere and retinal explant culture systems. During embryonic brain development, meteorin is highly expressed in neural stem and radial glia cells of the ventricular zone and immature neurons outside the ventricular zone but its expression disappears spontaneously as development proceeds except in GFAP-positive astrocytes. In cultured neurospheres, meteorin activates STAT3, and in turn increases the transcriptional activity of GFAP by enhancing the binding of STAT3 to the promoter. By meteorin stimulation, differentiating neurospheres show increased numbers of GFAP-positive cells, but the effect is abrogated by a blockade of the Jak-STAT3 pathway using either a Jak inhibitor or STAT3 siRNA. Furthermore, we expand our findings to the retina, and show that meteorin increases GFAP expression in Müller glia. Together, our results suggest that meteorin promotes GFAP-positive glia formation by mediating the Jak-STAT3 signaling pathway during both cortical stem cell differentiation and retinal glia development.

Abstract A23: Patterns of transcriptomic and proteomic expression of SOX4 may suggest a role in the pathophysiology and treatment of gliomas

Abstract Introduction: The SOX4 gene encodes a high-mobility group (HMG)-box transcription factor involved in embryonic differentiation and development and, later, is involved in signal transduction through the TGF-beta, IL5-R, and WNT pathways. Abnormal expression of SOX4 is associated with numerous malignancies, including those of the central nervous system. Its role as a potential etiologic agent and therapeutic target in glioblastoma is of particular interest given the limited treatment options and universally poor prognosis of these tumors. Notwithstanding, the fundamental patterns of transcriptome and proteome-level expression of SOX4 remain inadequately characterized across the glioma spectrum. We believe that this may be critically important to understanding the development, maintenance, and progression of gliomas; and, more importantly, represents a necessary step toward exploring the potential of SOX4 as a target in translational glioma therapy. Methods: We used microarray analysis to analyze transcriptome-level expression of the SOX4 gene using tumor tissue from 43 patients with World Health Organization (WHO) grade I-IV gliomas and validated these results using RT-PCR. We also conducted qualitative characterization and semi-quantitative analysis of the protein-level expression of SOX4 in a subset of this population and in primary and transformed glioma cell lines using immunofluorescence and mass spectrometry. Subgroup analysis was performed in a supervised and unsupervised fashion using an integrated data analysis model incorporating the results of the transcriptomic and proteomic investigations. Results: Transcriptome analysis demonstrates SOX4 mRNA overexpression in all glioma specimens. The magnitude of overexpression varies between patients, but there is insufficient evidence to suggest an independent correlation between the magnitude of differential expression and either WHO tumor grade or survival phenotype in low- or high-grade gliomas. Protein-level investigation indicates that, while transformed cell lines demonstrate almost exclusive localization of SOX4 to the nucleus, primary cell lines and surgical tissue specimens of from tumors of all WHO grades exhibit both nuclear and cytoplasmic localization of the SOX4 protein. The relative distribution of SOX4 protein between these compartments is variable and is not related to WHO grade. Conclusions: The SOX4 gene is overexpressed in all grades of gliomas, and the magnitude of overexpression differs between patients. The gene product localizes variably to the nucleus and cytoplasm in clinical specimens, the functional significance of which remains to be determined. We find insufficient evidence from our integrated genomic and proteomic analysis to suggest that the magnitude of SOX4 gene expression is an independent correlate or a direct predictor of survival in patients with gliomas. Rather than defining genotypic tumor subgroups, our findings suggest that SOX4 overexpression may be a common feature of gliomas, independent of tumor grade or clinical phenotype. This raises the possibility that abnormal expression of SOX4 may play a fundamental role in the development of all gliomas, a finding which may be logical given its role in early development and differentiation of embryologic glia. Ongoing investigation is required to more thoroughly characterize the contribution of SOX4 overexpression to the pathophysiology of gliomas, which is essential to understanding the translational therapeutic potential of SOX4. Citation Information: Clin Cancer Res 2010;16(7 Suppl):A23

Preparation of Rat Brain Aggregate Cultures for Neuron and Glia Development Studies

An in vitro system that recapitulates the development and differentiation of progenitors into mature neurons and glia in the central nervous system (CNS) would provide a powerful platform for neuroscientists to investigate axo-glial interactions, properties and differentiation of multipotent progenitors, and progression of oligodendroglial lineage cells at the cellular and molecular level. We describe here a CNS aggregate culture system from embryonic rat forebrains, which can be maintained in a serum-free medium up to 3-4 weeks and is used in our laboratory as a model to study neuron-glia interaction and CNS myelination. This video clip will demonstrate how to isolate and grow these CNS aggregate cultures from E16 rat brain. Furthermore, from the same brain dissection, highly enriched regular dissociated neuronal cultures can be readily obtained and used for various studies on CNS neurons or used for co-cultures with other cells.

Preparation of Rat Brain Aggregate Cultures for Neuron and Glia Development Studies

Preparation of Rat Brain Aggregate Cultures for Neuron and Glia Development Studies

Embryonic development of glial cells and myelin in the shark, Chiloscyllium punctatum

Glial cells are responsible for a wide range of functions in the nervous system of vertebrates. The myelinated nervous systems of extant elasmobranchs have the longest independent history of all gnathostomes. Much is known about the development of glia in other jawed vertebrates, but research in elasmobranchs is just beginning to reveal the mechanisms guiding neurodevelopment. This study examines the development of glial cells in the bamboo shark, Chiloscyllium punctatum, by identifying the expression pattern of several classic glial and myelin proteins. We show for the first time that glial development in the bamboo shark ( C. punctamum) embryo follows closely the one observed in other vertebrates and that neural development seems to proceed at a faster rate in the PNS than in the CNS. In addition, we observed more myelinated tracts in the PNS than in the CNS, and as early as stage 32, suggesting that the ontogeny of myelin in sharks is closer to osteichthyans than agnathans.

Organization and postembryonic development of glial cells in the adult central brain of Drosophila.

Glial cells exist throughout the nervous system, and play essential roles in various aspects of neural development and function. Distinct types of glia may govern diverse glial functions. To determine the roles of glia requires systematic characterization of glia diversity and development. In the adult Drosophila central brain, we identify five different types of glia based on its location, morphology, marker expression, and development. Perineurial and subperineurial glia reside in two separate single-cell layers on the brain surface, cortex glia form a glial mesh in the brain cortex where neuronal cell bodies reside, while ensheathing and astrocyte-like glia enwrap and infiltrate into neuropils, respectively. Clonal analysis reveals that distinct glial types derive from different precursors, and that most adult perineurial, ensheathing, and astrocyte-like glia are produced after embryogenesis. Notably, perineurial glial cells are made locally on the brain surface without the involvement of gcm (glial cell missing). In contrast, the widespread ensheathing and astrocyte-like glia derive from specific brain regions in a gcm-dependent manner. This study documents glia diversity in the adult fly brain and demonstrates involvement of different developmental programs in the derivation of distinct types of glia. It lays an essential foundation for studying glia development and function in the Drosophila brain.

SHP2 is a regulator of peripheral glia development and myelination

SHP2 is a regulator of peripheral glia development and myelination

Notch-regulated perineurium development from zebrafish spinal cord

In the developing central nervous system, nerve fascicles are surrounded by a protective sheath known as the perineurium. Perineurium is composed of perineurial cells that have both epithelial and myofibroblastoid properties, including tight and gap junctions and contractility. However, the molecular mechanism that governs perineurial development remains unclear. Here we focused on fabp7a, a brain lipid binding protein that is reportedly crucial for the proper differentiation of radial glial progenitor cells. Our study reveals that fabp7a is expressed in the lateral floor plate cells, and later perineurial glia in the spinal cord of zebrafish embryos. Furthermore, Notch signaling regulated perineurial glia development by maintaining fabp7a-expressing cells, demonstrating a novel mechanism for perineurial development.

Development of satellite glia in mouse sympathetic ganglia: GDNF and GFRα1 are not essential

The phenotypic development of satellite cells in mouse sympathetic ganglia was examined by localizing the transcription factors, Sox10 and Phox2b, the neuronal marker, tyrosine hydroxylase (TH), and brain-derived fatty acid binding protein (B-FABP), which identifies glial precursors and mature glia. In E10.5 mice, most cells in the sympathetic chain expressed both Sox10 and Phox2b, with a minority of cells expressing Sox10 only or Phox2b only. In E11.5 mice, the majority of cells expressed Sox10 only or Phox2b only. B-FABP was colocalized with Sox10 in satellite glial precursors, which were located on the periphery of the ganglion. There was no overlap between B-FABP and Phox2b or B-FABP and TH. During subsequent development, the number of B-FABP+ cells increased and they became more common deep within the ganglion. In E12.5 and E18.5 mice, there was no overlap between Sox10 and Phox2b, and 98% of Sox10 cells were also B-FABP+. Satellite glial precursors in E11.5-E15.5 mice also expressed the GDNF-binding molecule, GFRalpha1. B-FABP immunoreactive cells did not express Ret or NCAM, two potential signaling molecules for GDNF/GFRalpha1. In E12.5 and E18.5 mice lacking GFRalpha1 or GDNF, the development of B-FABP immunoreactive satellite cells was normal, and hence neither GDNF or GFRalpha1 are essential for the development of satellite glia in sympathetic ganglia.

Mls-2andvab-3control glia development,hlh-17/Olig expression and glia-dependent neurite extension inC. elegans

Glia are essential components of nervous systems. However, genetic programs promoting glia development and regulating glia-neuron interactions have not been extensively explored. Here we describe transcriptional programs required for development and function of the C. elegans cephalic sheath (CEPsh) glia. We demonstrate ventral- and dorsal-restricted roles for the mls-2/Nkx/Hmx and vab-3/Pax6/Pax7 genes, respectively, in CEPsh glia differentiation and expression of the genes hlh-17/Olig and ptr-10/Patched-related. Using mls-2 and vab-3 mutants, as well as CEPsh glia-ablated animals, we show that CEPsh glia are important for sensory dendrite extension, axon guidance/branching within the nerve ring, and nerve ring assembly. We demonstrate that UNC-6/Netrin, expressed in ventral CEPsh glia, mediates glia-dependent axon guidance. Our results suggest possible similarities between CEPsh glia development and oligodendrocyte development in vertebrates, and demonstrate that C. elegans provides a unique environment for studying glial functions in vivo.

The transcriptome of retinal Müller glial cells

Müller glial cells are the major type of glia in the mammalian retina. To identify the molecular machinery that defines Müller glial cell identity and function, single cell gene expression profiling was performed on Affymetrix microarrays. Identification of a cluster of genes expressed at high levels suggests a Müller glia core transcriptome, which likely underlies many of the functions of Müller glia. Expression of components of the cell cycle machinery and the Notch pathway, as well as of growth factors, chemokines, and lipoproteins might allow communication between Müller glial cells and the neurons that they support, including modulation of neuronal activity. This approach revealed a set of transcripts that were not previously characterized in (Müller) glia; validation of the expression of some of these genes was performed by in situ hybridization. Genes expressed exclusively by Müller glia were identified as novel markers. In addition, a novel BAC transgenic mouse that expresses Cre in Müller glia cells was generated. The molecular fingerprint of Müller glia provides a foundation for further studies of Müller glia development and function in normal and diseased states.

Directing traffic in neural cells: determinants of receptor tyrosine kinase localization and cellular responses

The trafficking of receptor tyrosine kinases (RTKs) to distinct subcellular locations is essential for the specificity and fidelity of signal transduction and biological responses. This is particularly important in the PNS and CNS in which RTKs mediate key events in the development and maintenance of neurons and glia through a wide range of neural processes, including survival, proliferation, differentiation, neurite outgrowth, and synaptogenesis. The mechanisms that regulate the targeting of RTKs to their subcellular destinations for appropriate signal transduction, however, are still elusive. In this review, we discuss evidence for the spatial organization of signaling machinery into distinct subcellular compartments, as well as the role for ligand specificity, receptor sorting signals, and lipid raft microdomains in RTK targeting and the resultant cellular responses in neural cells.

Stem Cell Factor Functions as an Outgrowth-Promoting Factor to Enable Axon Exit from the Midline Intermediate Target

Commissural axons are attracted to the midline intermediate target by chemoattractants, but upon crossing the midline they switch off responsiveness to attractants and switch on responsiveness to midline repellents, which expel the axons from the midline and enable them to move on. Here we show that midline exit also requires the stimulation of axon outgrowth by Stem Cell Factor (SCF, also known as Steel Factor). SCF is expressed by midline floor plate cells, and its receptor Kit, a receptor tyrosine kinase, is expressed by commissural axons. In Steel and Kit mutant mice, the majority of commissural axons line up transiently at the contralateral edge of the floor plate, showing a delay in midline exit. In vitro, SCF selectively promotes outgrowth of postcrossing, but not precrossing, commissural axons. Our findings identify SCF as a guidance cue in the CNS, and provide evidence that exiting intermediate targets requires activation of outgrowth-promoting mechanisms.

Identification of direct regulatory targets of the transcription factor Sox10 based on function and conservation

BackgroundSox10, a member of the Sry-related HMG-Box gene family, is a critical transcription factor for several important cell lineages, most notably the neural crest stem cells and the derivative peripheral glial cells and melanocytes. Thus far, only a handful of direct target genes are known for this transcription factor limiting our understanding of the biological network it governs.ResultsWe describe identification of multiple direct regulatory target genes of Sox10 through a procedure based on function and conservation. By combining RNA interference technique and DNA microarray technology, we have identified a set of genes that show significant down-regulation upon introduction of Sox10 specific siRNA into Schwannoma cells. Subsequent comparative genomics analyses led to potential binding sites for Sox10 protein conserved across several mammalian species within the genomic region proximal to these genes. Multiple sites belonging to 4 different genes (proteolipid protein, Sox10, extracellular superoxide dismutase, and pleiotrophin) were shown to directly interact with Sox10 by chromatin immunoprecipitation assay. We further confirmed the direct regulation through the identified cis-element for one of the genes, extracellular superoxide dismutase, using electrophoretic mobility shift assay and reporter assay.ConclusionIn sum, the process of combining differential expression profiling and comparative genomics successfully led to further defining the role of Sox10, a critical transcription factor for the development of peripheral glia. Our strategy utilizing relatively accessible techniques and tools should be applicable to studying the function of other transcription factors.

Guided adhesion and outgrowth of a constrained network on tailormade surfaces

Event Abstract Back to Event Guided adhesion and outgrowth of a constrained network on tailormade surfaces Anke Wörz1*, Steffen Kandler2, Oswald Prucker1, Ulrich Egert3 and Jürgen Rühe1 1 Freiburg University, Department of Microsystems Engineering , Germany 2 Freiburg University, Neurobiology and Biophysics, Germany 3 Freiburg University, Department of Microsystems Engineering - Biomicrotechnology, Germany Planar micro-electrode arrays have now been used for some time to investigate the activity dynamics and response of neural networks to electrical or chemical stimuli. Constructing defined connectivity statistics under cell culture conditions that allow the maturation of the neuronal networks for a long period has not been achieved so far. Such networks would be useful to understand the influence of the composition, connectivity statistics, and plasticity in a neuronal network on the dynamics of electrical activity. Successful reports of constrained neuronal networks have used serum free medium to minimize the masking of the pattern by proteins. Serum free medium, however, impairs glia develop-ment, which has shown to have significant effects on network maturation and long-term vitality of the neurons, whereas serum containing medium may mask the patterned molecular layers (e.g. stamped proteins), which leads to a loss of constrained neuronal networks after several hours. The key issue is the control of the spatial and long-term stability of neuronal cell adhesion and neurite outgrowth by physicochemical surface modifications under cell culture conditions that allow long-term maintenance of these networks on a micro-scale. This can be achieved by using thin polymer coatings, whose cell adhesion property is not affected by serum-proteins. We report a simple way to tailor the surface-chemistry using a photochemical approach, leading to the covalent attachment of polymer layers to glass and MEA surfaces. We examined the biocompatibility of polymer layers with different properties, such as hydrophilicity and charge, and their potential to promote or inhibit neuronal cell adhesion. Finally, patterns with cell attractive domains were obtained using pin printing or -contact printing ( -CP) of polymer solutions. These patterns were able to guide neuronal cells in a constrained network and were stable over several weeks in a serum containing cell culture medium. Conference: Bernstein Symposium 2008, Munich, Germany, 8 Oct - 10 Oct, 2008. Presentation Type: Poster Presentation Topic: All Abstracts Citation: Wörz A, Kandler S, Prucker O, Egert U and Rühe J (2008). Guided adhesion and outgrowth of a constrained network on tailormade surfaces. Front. Comput. Neurosci. Conference Abstract: Bernstein Symposium 2008. doi: 10.3389/conf.neuro.10.2008.01.077 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Nov 2008; Published Online: 17 Nov 2008. * Correspondence: Anke Wörz, Freiburg University, Department of Microsystems Engineering, Freiburg, Germany, woerz@imtek.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Anke Wörz Steffen Kandler Oswald Prucker Ulrich Egert Jürgen Rühe Google Anke Wörz Steffen Kandler Oswald Prucker Ulrich Egert Jürgen Rühe Google Scholar Anke Wörz Steffen Kandler Oswald Prucker Ulrich Egert Jürgen Rühe PubMed Anke Wörz Steffen Kandler Oswald Prucker Ulrich Egert Jürgen Rühe Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Ets-1 Regulates Radial Glia Formation During Vertebrate Embryogenesis

Radial glia cells are the first distinguishable glial population derived from neural epithelial cells and serve as guides for migrating neurons and as neural progenitor cells in the developing brain. Despite their functional importance during neural development, the determination and differentiation of these cells remains poorly understood at the molecular level. Ets-1 and Ets-2, Ets (E26 transformation-specific) transcription factors, are vertebrate homologues of Drosophila pointed, which is expressed in a subset of glia cells and promotes different aspects of Drosophila glia cell differentiation. However, it remains unsolved that the function of Ets genes is conserved in vertebrate glia development. Here we report that Ets-1 but not Ets-2 is necessary for Xenopus radial glia formation and the activity of Ets-1 is sufficient for radial glia formation prior to neural tube closure. Furthermore, we show that Ras-MAPK (mitogen activated protein kinase) signaling, which acts as an upstream activator of Ets-1 in other biological processes, also regulates radial glia formation. A mutant form of Ets-1, which is not responsive to Ras-MAPK signaling, inhibits radial glia formation promoted by Ras-MAPK signaling. Together, our results show that Ets-1 activated by Ras-MAPK signaling promotes radial glia formation during Xenopus embryogenesis.

Development of sympathetic glia in mice

Two sorts of glial cell are associated with sympathetic ganglia — Schwann cells, which are associated with peripheral nerves, and sympathetic (satellite) glia, which support neurons in ganglia. The development of sympathetic neurons has been very well studied over many years, but surprisingly little is known about the development of sympathetic glia. We examined the development of sympathetic glia in mouse sympathetic ganglia in both wild type and transgenic mice. Previous studies have shown that brain-derived fatty acid binding protein (B-FABP) is a marker of glial precursors. In wild type mice, B-FABP+cells were first detected immunohistochemically at E11.5. The first BFABP+cells appeared in the most superficial layer of the ganglion, but by E12.5 they were also present deeper in the ganglion, where they continued to increase in number until the adult density and appearance was reached by E16.5. B-FABP was never colocalised with immunoreactivity to tyrosine hydroxylase at any embryonic stage. A marker of mature peripheral glial cells, S100b, did not appear until E15.5. In heterozygote mice in which green fluorescent protein (GFP) expression is driven by the Ret-promoter, B-FABP was never co-localised with GFP. However, sympathetic glial precursors did express high levels of immunoreactivity for GDNF family ligand receptor alpha 1 (GFRalpha1) between E10.5 and E14.5. GDNF-GFRalpha1 can utilise neural cell adhesion molecule (NCAM) rather than Ret as the transmembrane signalling component. NCAM was present in B-FABP immunoreactive cells. An examination of GDNF null mutants suggested that there were no obvious consequences to satellite glial development of the loss of GDNF.

CNS midline cells influence the division and survival of lateral glia in the Drosophila nervous system

Central nervous system (CNS) midline cells are essential for identity determination and differentiation of neurons in the Drosophila nervous system. It is not clear, however, whether CNS midline cells are also involved in the development of lateral glial cells. The roles of CNS midline cells in lateral glia development were elucidated using general markers for lateral glia, such as glial cell missing and reverse polarity, and specific enhancer trap lines labeling the longitudinal, A, B, medial cell body, peripheral, and exit glia. We found that CNS midline cells were necessary for the proper expression of glial cell missing, reverse polarity, and other lateral glia markers only during the later stages of development, suggesting that they are not required for initial identity determination. Instead, CNS midline cells appear to be necessary for proper division and survival of lateral glia. CNS midline cells were also required for proper positioning of three exit glia at the junction of segmental and intersegmental nerves, as well as some peripheral glia along motor and sensory axon pathways. This study demonstrated that CNS midline cells are extrinsically required for the proper division, migration, and survival of various classes of lateral glia from the ventral neuroectoderm.

Comparative developmental neurotoxicity of organophosphates in vivo: Transcriptional responses of pathways for brain cell development, cell signaling, cytotoxicity and neurotransmitter systems

Organophosphates affect mammalian brain development through a variety of mechanisms beyond their shared property of cholinesterase inhibition. We used microarrays to characterize similarities and differences in transcriptional responses to chlorpyrifos and diazinon, assessing defined gene groupings for the pathways known to be associated with the mechanisms and/or outcomes of chlorpyrifos-induced developmental neurotoxicity. We exposed neonatal rats to daily doses of chlorpyrifos (1 mg/kg) or diazinon (1 or 2 mg/kg) on postnatal days 1–4 and evaluated gene expression profiles in brainstem and forebrain on day 5; these doses produce little or no cholinesterase inhibition. We evaluated pathways for general neural cell development, cell signaling, cytotoxicity and neurotransmitter systems, and identified significant differences for >60% of 252 genes. Chlorpyrifos elicited major transcriptional changes in genes involved in neural cell growth, development of glia and myelin, transcriptional factors involved in neural cell differentiation, cAMP-related cell signaling, apoptosis, oxidative stress, excitotoxicity, and development of neurotransmitter synthesis, storage and receptors for acetylcholine, serotonin, norepinephrine and dopamine. Diazinon had similar effects on many of the same processes but also showed major differences from chlorpyrifos. Our results buttress the idea that different organophosphates target multiple pathways involved in neural cell development but also that they deviate in key aspects that may contribute to disparate neurodevelopmental outcomes. Equally important, these pathways are compromised at exposures that are unrelated to biologically significant cholinesterase inhibition and its associated signs of systemic toxicity. The approach used here demonstrates how planned comparisons with microarrays can be used to screen for developmental neurotoxicity.

Critical role of Brg1 member of the SWI/SNF chromatin remodeling complex during neurogenesis and neural crest induction in zebrafish

Brg1 is a member of the SWI/SNF chromatin-remodeling complex, and in some organisms Brg1 has been shown to interact with beta-catenin and positively control the TCF/LEF transcription factor that is located downstream of the Wnt signal transduction pathway. During development, TCF/LEF activity is critical during neurogenesis and head induction. In zebrafish, Brg1-deficient embryos exhibit retinal cell differentiation and eye defects; however, the role of Brg1 in neurogenesis and neural crest cell induction remains elusive. We used zebrafish deficient in Brg1 (yng) or Brg1 specific-morpholino oligonucleotide-mediated knockdown to analyze the embryonic requirements of Brg1. Our results indicate that reduction in Brg1 expression leads to the expansion of the forebrain-specific transcription factor, six3, and marked reduction in expression of the mid/hind-brain boundary and hind-brain genes, engrailed2 and krox20, respectively. At 12 hpf, the expression of neural crest specifiers are severely affected in Brg1-morpholino-injected embryos. These results suggest that Brg1 is involved in neural crest induction, which is critical for the development of neurons, glia, pigment cells, and craniofacial structures. Brg1 is a maternal factor, and brg1-deficient embryos bearing the yng mutation derived from heterozygote intercrosses exhibit lesser effects on neural crest-specific gene expression, but show defects in neurogenesis and neural crest cell differentiation. This is exhibited by the aberrant brain patterning, a reduction in the sensory neurons, and craniofacial defects. These results further elucidate the critical role for Brg1 in neurogenesis, neural crest induction, and differentiation.