Proliferation Of Neuronal Precursors Research Articles

Microglial control of neuronal development via somatic purinergic junctions.

SummaryMicroglia, the resident immune cells of the brain, play important roles during development. Although bi-directional communication between microglia and neuronal progenitors or immature neurons has been demonstrated, the main sites of interaction and the underlying mechanisms remain elusive. By using advanced methods, here we provide evidence that microglial processes form specialized contacts with the cell bodies of developing neurons throughout embryonic, early postnatal, and adult neurogenesis. These early developmental contacts are highly reminiscent of somatic purinergic junctions that are instrumental for microglia-neuron communication in the adult brain. The formation and maintenance of these junctions is regulated by functional microglial P2Y12 receptors, and deletion of P2Y12Rs disturbs proliferation of neuronal precursors and leads to aberrant cortical cytoarchitecture during development and in adulthood. We propose that early developmental formation of somatic purinergic junctions represents an important interface for microglia to monitor the status of immature neurons and control neurodevelopment.

Limb Remote Ischemic Conditioning Promotes Neurogenesis after Cerebral Ischemia by Modulating miR-449b/Notch1 Pathway in Mice.

Neurogenesis plays an important role in the prognosis of stroke patients and is known to be promoted by the activation of the Notch1 signaling pathway. Studies on the airway epithelium have shown that miR-449b represses the Notch pathway. The study aimed to investigate whether limb remote ischemic conditioning (LRIC) was able to promote neurogenesis in cerebral ischemic mice, and to investigate the role of the miR-449b/Notch1 pathway in LRIC-induced neuroprotection. Male C57BL/6 mice (22–25 g) were subjected to transient middle cerebral artery occlusion (MCAO), and LRIC was performed in the bilateral lower limbs immediately after MCA occlusion. Immunofluorescence staining was performed to assess neurogenesis. The cell line NE-4C was used to elucidate the proliferation of neuronal stem cells in 8% O2. After LRIC treatment on day 28, mice recovered neurological function. Neuronal precursor proliferation was enhanced in the SVZ, and neuronal precursor migration was enhanced in the basal ganglia on day 7. LRIC promoted the improvement of neurological function in mice on day 28, promoted neuronal precursor proliferation in the SVZ, and enhanced neuronal precursor migration in the basal ganglia on day 7. The neurological function score was negatively correlated with the number of BrdU-positive/DCX-positive cells in the SVZ and striatum. LRIC promoted activated Notch1 protein expression in the SVZ and substantially downregulated miR-449b levels in the SVZ and plasma. In vitro, miR-449b was found to target Notch1. Lentivirus-mediated miR-449b knockdown increased Notch1 levels in NE-4C cells and increased proliferation in the cells. The effects of miR-449b inhibition on neurogenesis were ablated by the application of Notch1 shRNA. Our study showed that LRIC promoted the proliferation and migration of neural stem cells after MCAO, and these effects were modulated by the miR-449b/Notch1 pathway.

The Primary Ciliary Deficits in Cerebellar Bergmann Glia of the Mouse Model of Fragile X Syndrome.

Primary cilia are non-motile cilia that function as antennae for cells to sense signals. Deficits of primary cilia cause ciliopathies, leading to the pathogenesis of various developmental disorders; however, the contribution of primary cilia to neurodevelopmental disorders is largely unknown. Fragile X syndrome (FXS) is a genetically inherited disorder and isthe most common known cause of autism spectrum disorders. FXS is caused by the silencing of the fragile X mental retardation 1 (FMR1) gene, which encodes for the fragile X mental retardation protein (FMRP). Here, we discovered a reduction in the number of primary cilia and the Sonic hedgehog (Shh) signaling in cerebellar Bergmann glia of Fmr1 KO mice. We further found reduced granule neuron precursor (GNP) proliferation and thickness of the external germinal layer (EGL) in Fmr1 KO mice, implicating that primary ciliary deficits in Bergmann glia may contribute to cerebellar developmental phenotypes in FXS, as Shh signaling through primary cilia in Bergmann glia is known to mediate proper GNP proliferation in the EGL. Taken together, our study demonstrates that FMRP loss leads to primary ciliary deficits in cerebellar Bergmann glia which may contribute to cerebellar deficits in FXS.

Restricted Proliferation During Neurogenesis Contributes to Regionalisation of the Amphioxus Nervous System.

The central nervous system of the cephalochordate amphioxus consists of a dorsal neural tube with an anterior brain. Two decades of gene expression analyses in developing amphioxus embryos have shown that, despite apparent morphological simplicity, the amphioxus neural tube is highly regionalised at the molecular level. However, little is known about the morphogenetic mechanisms regulating the spatiotemporal emergence of cell types at distinct sites of the neural axis and how their arrangements contribute to the overall neural architecture. In vertebrates, proliferation is key to provide appropriate cell numbers of specific types to particular areas of the nervous system as development proceeds, but in amphioxus proliferation has never been studied at this level of detail, nor in the specific context of neurogenesis. Here, we describe the dynamics of cell division during the formation of the central nervous system in amphioxus embryos, and identify specific regions of the nervous system that depend on proliferation of neuronal precursors at precise time-points for their maturation. By labelling proliferating cells in vivo at specific time points in development, and inhibiting cell division during neurulation, we demonstrate that localised proliferation in the anterior cerebral vesicle is required to establish the full cell type repertoire of the frontal eye complex and the putative hypothalamic region of the amphioxus brain, while posterior proliferating progenitors, which were found here to derive from the dorsal lip of the blastopore, contribute to elongation of the caudal floor plate. Between these proliferative domains, we find that trunk nervous system differentiation is independent from cell division, in which proliferation decreases during neurulation and resumes at the early larval stage. Taken together, our results highlight the importance of proliferation as a tightly controlled mechanism for shaping and regionalising the amphioxus neural axis during development, by addition of new cells fated to particular types, or by influencing tissue geometry.

Hypoxic postconditioning promotes neurogenesis by modulating the metabolism of neural stem cells after cerebral ischemia

Ischemic stroke is one of the most lethal and severely disabling diseases that seriously affects human health and quality of life. The maintenance of self-renewal and differentiation of neural stem cells are closely related to metabolism. This study aimed to investigate whether hypoxic postconditioning (HPC) could promote neurogenesis after ischemic stroke, and to investigate the role of neuronal stem cell metabolism in HPC-induced neuroprotection. Male C57BL/6 mice were subjected to transient middle cerebral artery occlusion (MCAO), and HPC was performed for 3 h per day. Immunofluorescence staining was used to assess neurogenesis. The cell line NE-4C was used to elucidate the proliferation of neuronal stem cells in 21% O2 or 8% O2. HPC promoted the recovery of neurological function in mice on day 14. HPC promoted neuronal precursor proliferation in the subventricular zone (SVZ) on day 7 and enhanced neuronal precursor migration in the basal ganglia and cortex on day 14. Fatty acid oxidation (FAO) and glycolysis of neural stem cells in the SVZ changed after MCAO with or without HPC. HPC promoted the proliferation of NE-4C stem cells, decreased FAO and increased glycolysis. All these beneficial effects of HPC were ablated by the application of an FAO activator or a glycolysis inhibitor. In conclusion, cerebral ischemia modulated the FAO and glycolysis of neural stem cells. HPC promoted the proliferation and migration of neural stem cells after MCAO, and these effects may be related to the regulation of metabolism, including FAO and glycolysis.

Long-term monitoring of chronic demyelination and remyelination in a rat ischemic stroke model using macromolecular proton fraction mapping

Remyelination is a key process enabling post-stroke brain tissue recovery and plasticity. This study aimed to explore the feasibility of demyelination and remyelination monitoring in experimental stroke from the acute to chronic stage using an emerging myelin imaging biomarker, macromolecular proton fraction (MPF). After stroke induction by transient middle cerebral artery occlusion, rats underwent repeated MRI examinations during 85 days after surgery with histological endpoints for the animal subgroups on the 7th, 21st, 56th, and 85th days. MPF maps revealed two sub-regions within the infarct characterized by distinct temporal profiles exhibiting either a persistent decrease by 30%–40% or a transient decrease followed by return to nearly normal values after one month of observation. Myelin histology confirmed that these sub-regions had nearly similar extent of demyelination in the sub-acute phase and then demonstrated either chronic demyelination or remyelination. The remyelination zones also exhibited active axonal regrowth, reconstitution of compact fiber bundles, and proliferation of neuronal and oligodendroglial precursors. The demyelination zones showed more extensive astrogliosis from the 21st day endpoint. Both sub-regions had substantially depleted neuronal population over all endpoints. These results histologically validate MPF mapping as a novel approach for quantitative assessment of myelin damage and repair in ischemic stroke.

Neutrophil-like Cell-Membrane-Coated Nanozyme Therapy for Ischemic Brain Damage and Long-Term Neurological Functional Recovery.

Oxidative stress and a series of excessive inflammatory responses are major obstacles for neurological functional recovery after ischemic stroke. Effective noninvasive anti-inflammatory therapies are urgently needed. However, unsatisfactory therapeutic efficacy of current drugs and inadequate drug delivery to the damaged brain are major problems. Nanozymes with robust anti-inflammatory and antioxidative stress properties possess therapeutic possibility for ischemic stroke. However, insufficiency of nanozyme accumulation in the ischemic brain by noninvasive administration hindered their application. Herein, we report a neutrophil-like cell-membrane-coated mesoporous Prussian blue nanozyme (MPBzyme@NCM) to realize noninvasive active-targeting therapy for ischemic stroke by improving the delivery of a nanozyme to the damaged brain based on the innate connection between inflamed brain microvascular endothelial cells and neutrophils after stroke. The long-term in vivo therapeutic efficacy of MPBzyme@NCM for ischemic stroke was illustrated in detail after being delivered into the damaged brain and uptake by microglia. Moreover, the detailed mechanism of ischemic stroke therapy via MPBzyme@NCM uptake by microglia was further studied, including microglia polarization toward M2, reduced recruitment of neutrophils, decreased apoptosis of neurons, and proliferation of neural stem cells, neuronal precursors, and neurons. This strategy may provide an applicative perspective for nanozyme therapy in brain diseases.

Simultaneous Brg1 Knockout and MYCN Overexpression in Cerebellar Granule Neuron Precursors Is Insufficient to Drive Tumor Formation but Temporarily Enhances their Proliferation and Delays their Migration

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. According to the World Health Organization (WHO) classification of central nervous system (CNS) tumors, this embryonal tumor is divided into a wingless (WNT)-activated, Sonic hedgehog (SHH)-activated, and non-WNT/non-SHH entity. The latter is poorly defined but frequently carries mutations in Brahma-related gene 1 (BRG1) or amplifications of MYCN. Here, we investigated whether a combination of a Brg1 knockout and an overexpression of MYCN in cerebellar granule neuron precursors or multipotent neural stem cells is sufficient to drive brain tumor formation in mice. To this end, we generated Math1-creERT2::Brg1fl/fl::lslMYCN and hGFAP-cre::Brg1fl/fl::lslMYCN mice, respectively. We did not observe brain tumor formation in any of these models. hGFAP-cre::Brg1fl/fl::lslMYCN mice revealed severe CNS abnormalities with short survival, similar to the situation with a sole loss of Brg1, as we previously described. Investigation of Math1-creERT2::Brg1fl/fl::lslMYCN mice with a tamoxifen induction at postnatal day 3 revealed a regular survival but significant increase in cerebellar granule neuron precursor proliferation, followed by a delayed inward migration of these cells. This is in stark contrast to the hypoplastic cerebellum that we previously observed after embryonic deletion of Brg1 in Math1 positive cerebellar granule neurons. Our results indicate a time-specific function of Brg1 in cerebellar granule neuron precursors. Yet, the exact temporal and spatial origin of non-WNT/non-SHH MB remains unclear.

PHF10, a Subunit of the PBAF Chromatin Remodeling Complex, Changes Its Localization and Interacts with c-FOS during the Initiation of Long-Term Potentiation in Neuronal Culture

The PBAF chromatin remodeling complex interacts with many transcriptional activators and is recruited to target chromatin regions. PBAF plays an important role in maintaining and modifying the chromatin structure in mammalian cells. A subunit of the PBAF complex, the PHF10 transcription factor, is required for proliferation of neuronal precursors in the early stages of mouse brain development and gene expression in differentiated neurons. We showed that PHF10 interacts with the protein product of the early response gene </>c-FOS, the c-FOS transcriptional activator, which is expressed in response to the induction of long-term potentiation (LTP). LTP induction triggers the transcription of genes and the synthesis of proteins that provide changes that lead to the establishment of long-term contacts between neurons. We showed that in cells in differentiated neuronal culture, after the induction of LTP, expression of c-FOS, which is initially localized in the cytoplasm and then moves to the nucleus, begins. PHF10 is expressed in neuronal cells prior to LTP induction and has nuclear localization. However, 1 h after LTP induction, PHF10 is detected in the cytoplasm together with c-FOS, and then moves into the nucleus with it. Importantly, this behavior of PHF10 in response to KC1 stimulation is specific for neuronal cultures. It is assumed that during LTP, PHF10 together with c-FOS participates in the activation of secondary response genes that regulate the maintenance of plastic modifications and homeostasis of neuronal synapses. The PHF10 export from the nucleus and its rapid return together with c-FOS to the nucleus is possibly necessary for the rapid modulation of expression of target secondary response genes during LTP.

Mitogen and Stress-activated Protein Kinase 1 Negatively Regulates Hippocampal Neurogenesis

Neurogenesis in the subgranular zone (SGZ) of the adult hippocampus can be stimulated by a variety of means, including via exposure of experimental animals to an enriched environment that provides additional sensory, social, and motor stimulation. Tangible health and cognitive benefits accrue in enriched animals, including the amelioration of signs modelling psychiatric, neurological and neurodegenerative conditions that affect humans, which may in part be due to enhanced production of neurons. A key factor in the neuronal response to enrichment is the release of brain-derived neurotrophic factor (BDNF) and the activation of the Mitogen-Activated Protein Kinase (MAPK) cascade, which can lead to the stimulation of neurogenesis. Mitogen- and Stress-Activated protein Kinase 1 (MSK1) is a nuclear enzyme downstream of BDNF and MAPK that regulates transcription. MSK1 has previously been implicated in both basal and stimulated neurogenesis on the basis of studies with mice lacking MSK1 protein. In the present study, using mice in which only the kinase activity of MSK1 is lacking, we show that the rate of cellular proliferation in the SGZ (Ki-67 staining) is unaffected by the MSK1 kinase-dead (KD) mutation, and no different from controls levels after five weeks of enrichment. However, compared to wild-type mice, the number of doublecortin (DCX)-positive cells was greater in both standard-housed and enriched MSK1 KD mice. These observations suggest that, while MSK1 does not influence the basal rate of proliferation of neuronal precursors, MSK1 negatively regulates the number of cells destined to become neurons, potentially as a homeostatic control on the number of new neurons integrating into the dentate gyrus.

Deficits in developmental neurogenesis and dendritic spine maturation in mice lacking the serine protease inhibitor neuroserpin

Neuroserpin is a serine protease inhibitor of the nervous system required for normal synaptic plasticity and regulating cognitive, emotional and social behavior in mice. The high expression level of neuroserpin detected at late stages of nervous system formation in most regions of the brain points to a function in neurodevelopment. In order to evaluate the contribution of neuroserpin to brain development, we investigated developmental neurogenesis and neuronal differentiation in the hippocampus of neuroserpin-deficient mice. Moreover, synaptic reorganization and composition of perineuronal net were studied during maturation and stabilization of hippocampal circuits. We showed that absence of neuroserpin results in early termination of neuronal precursor proliferation and premature neuronal differentiation in the first postnatal weeks. Additionally, at the end of the critical period neuroserpin-deficient mice had changed morphology of dendritic spines towards a more mature phenotype. This was accompanied by increased protein levels and reduced proteolytic cleavage of aggrecan, a perineuronal net core protein. These data suggest a role for neuroserpin in coordinating generation and maturation of the hippocampus, which is essential for establishment of an appropriate neuronal network.

Cortical and Commissural Defects Upon HCF-1 Loss in Nkx2.1-Derived Embryonic Neurons and Glia.

Formation of the cerebral cortex and commissures involves a complex developmental process defined by multiple molecular mechanisms governing proliferation of neuronal and glial precursors, neuronal and glial migration, and patterning events. Failure in any of these processes can lead to malformations. Here, we study the role of HCF‐1 in these processes. HCF‐1 is a conserved metazoan transcriptional co‐regulator long implicated in cell proliferation and more recently in human metabolic disorders and mental retardation. Loss of HCF‐1 in a subset of ventral telencephalic Nkx2.1‐positive progenitors leads to reduced numbers of GABAergic interneurons and glia, owing not to decreased proliferation but rather to increased apoptosis before cell migration. The loss of these cells leads to development of severe commissural and cortical defects in early postnatal mouse brains. These defects include mild and severe structural defects of the corpus callosum and anterior commissure, respectively, and increased folding of the cortex resembling polymicrogyria. Hence, in addition to its well‐established role in cell proliferation, HCF‐1 is important for organ development, here the brain.

Genetic ablation of tau in postnatal neurons rescues decreased adult hippocampal neurogenesis in a tauopathy model.

Impaired adult hippocampal neurogenesis has been reported as a feature of Alzheimer's disease and other tauopathies and might contribute to defects in learning and memory in these diseases. To assess the interference of tau pathology, a common key-lesion in these diseases, with adult hippocampal neurogenesis we analyzed adult neurogenesis in the hippocampal dentate gyrus in wild-type mice, Tg30 mice expressing a FTDP-17 mutant tau and the same Tg30 mice deficient for mouse tau (Tg30/tauKO). The volume of the granular layer, the number of granule cells and of neuronal precursors expressing the immature markers DCX or 3R-tau were analyzed in the dentate gyrus (DG) using unbiased stereological methods. The co-localization of neurogenic markers with the human mutant tau was also analyzed. We observed a significant reduction of the volume of the granular layer and of granule cells number in mutant tau Tg30 mice, but not in Tg30/tauKO mice. The number of neuronal precursors expressing the immature markers DCX or 3R-tau (the latter only expressed in wild-type and Tg30 mice) and the number of cells expressing the proliferation marker Ki-67 in the neurogenic subgranular zone of the DG was reduced in Tg30 but not in Tg30/tauKO mice. The density of phosphotau positive cells in the DG and the level of soluble human phosphotau was lower in Tg30/tauKO compared to Tg30 mice. The human mutant tau was expressed in mature granule cells in Tg30 and Tg30/tauKO mice but was not expressed in Sox2 positive neural stem cells and in DCX positive neuronal precursors/immature newborn neurons. These results demonstrate an impairment of adult hippocampal neurogenesis in a FTDP-17 mutant tau mice resulting from a decrease of proliferation affecting the pool of neuronal precursors. The mutant tau was not expressed in precursors cells in these mutant tau mice, suggesting that this neurogenic defect is cell non-autonomous. Interestingly, expression of endogenous wild-type tau in mature granule cells was necessary to observe this toxic effect of human mutant tau, since this impaired adult neurogenesis was rescued by lowering tau expression in Tg30/tauKO mice. These observations suggest that development of tau pathology in granule cells of the dentate gyrus is responsible for reduction of adult hippocampal neurogenesis also in human tauopathies by impairing proliferation of neuronal precursors, and that reduction of tau expression might be an approach to rescue this impairment.

MEPO promotes neurogenesis and angiogenesis but suppresses gliogenesis in mice with acute ischemic stroke

Previously study has proved the non-erythropoietic mutant erythropoietin (MEPO) exerted neuroprotective effects against ischemic cerebral injury, with an efficacy similar to that of wild-type EPO. This study investigates its effects on neurogenesis, angiogenesis, and gliogenesis in cerebral ischemic mice. Male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO) and reperfusion. EPO (5000 U/kg), MEPO (5000 U/kg) or equal volume of normal saline was injected intraperitoneally. Neurological function was evaluated by Rota-rod test, Neurological severity scores (NSS) and Adhesive removal test. After ischemia and reperfusion (I/R), the survival rate, brain tissue loss, neurogenesis, angiogenesis and gliogenesis were detected by Nissl staining, Immunofluorescence and Western blot, respectively. The results shown that MEPO significantly increased survival rate, reduced brain tissue loss, and improved neurological function after MCAO (P < 0.05). Furthermore, MEPO obviously enhanced the proliferation of neuronal precursors (DCX) and promoted its differentiation into mature neurons (NeuN) (P < 0.05). In addition, compared to normal saline treatment mice, MEPO increased the number of BrdU-positive cells in the cerebral vasculature (P < 0.05). Whereas, MEPO treatment also reduced the numbers of newly generated astrocytes (GFAP) and microglia (Iba1) (P < 0.05). Among all the tests in this study, there was no significant difference between EPO group and MEPO group. Taken together, MEPO promoted the regeneration of neurons and blood vessels in peripheral area of infarction, and suppressed the gliogenesis, thus promoting neurogenesis, improving neurological function and survival rate. Our findings suggest that the MEPO may be a therapeutic drug for ischemic stroke intervention.

Pparα deficiency inhibits the proliferation of neuronal and glial precursors in the zebrafish central nervous system.

Many molecules and signaling pathways involved in neural development play a role in neurodegenerative diseases and brain tumor progression. Peroxisome proliferator-activated receptor (PPAR) proteins regulate the differentiation of tissues and the progression of many diseases. However, the role of these proteins in neural development is unclear. We examined the function of Pparα in the neural development of zebrafish. Two duplicate paralogs for mammalian PPARA/Ppara, namely pparaa and pparab, are present in the zebrafish genome. Both pparaa and pparab are expressed in the developing central nervous system in zebrafish embryos. Inhibiting the function of Pparα by using either the PPARα/Pparα antagonist GW6471 or pparaa or pparab truncated constructs produced identical phenotypes, which were sufficient to reduce the proliferation of neuronal and glial precursor cells without affecting the formation of neural progenitors. We demonstrated that both Pparαa and Pparαb proteins are essential regulators of the proliferation of neuronal and glial precursors. This study provides a better understanding of the functions of PPARα/Pparα in neural development and further expands our knowledge of the potential role of PPARα/Pparα in neurological disorders and brain tumors. Developmental Dynamics 247:1264-1275, 2018. © 2018 Wiley Periodicals, Inc.

The Transcriptional Regulator SnoN Promotes the Proliferation of Cerebellar Granule Neuron Precursors in the Postnatal Mouse Brain.

Control of neuronal precursor cell proliferation is essential for normal brain development, and deregulation of this fundamental developmental event contributes to brain diseases. Typically, neuronal precursor cell proliferation extends over long periods of time during brain development. However, how neuronal precursor proliferation is regulated in a temporally specific manner remains to be elucidated. Here, we report that conditional KO of the transcriptional regulator SnoN in cerebellar granule neuron precursors robustly inhibits the proliferation of these cells and promotes their cell cycle exit at later stages of cerebellar development in the postnatal male and female mouse brain. In laser capture microdissection followed by RNA-Seq, designed to profile gene expression specifically in the external granule layer of the cerebellum, we find that SnoN promotes the expression of cell proliferation genes and concomitantly represses differentiation genes in granule neuron precursors in vivo Remarkably, bioinformatics analyses reveal that SnoN-regulated genes contain binding sites for the transcription factors N-myc and Pax6, which promote the proliferation and differentiation of granule neuron precursors, respectively. Accordingly, we uncover novel physical interactions of SnoN with N-myc and Pax6 in cells. In behavior analyses, conditional KO of SnoN impairs cerebellar-dependent learning in a delayed eye-blink conditioning paradigm, suggesting that SnoN-regulation of granule neuron precursor proliferation bears functional consequences at the organismal level. Our findings define a novel function and mechanism for the major transcriptional regulator SnoN in the control of granule neuron precursor proliferation in the mammalian brain.SIGNIFICANCE STATEMENT This study reports the discovery that the transcriptional regulator SnoN plays a crucial role in the proliferation of cerebellar granule neuron precursors in the postnatal mouse brain. Conditional KO of SnoN in granule neuron precursors robustly inhibits the proliferation of these cells and promotes their cycle exit specifically at later stages of cerebellar development, with biological consequences of impaired cerebellar-dependent learning. Genomics and bioinformatics analyses reveal that SnoN promotes the expression of cell proliferation genes and concomitantly represses cell differentiation genes in vivo Although SnoN has been implicated in distinct aspects of the development of postmitotic neurons, this study identifies a novel function for SnoN in neuronal precursors in the mammalian brain.

Dynarrestin, a Novel Inhibitor of Cytoplasmic Dynein

Aberrant hedgehog (Hh) signaling contributes to the pathogenesis of multiple cancers. Available inhibitors target Smoothened (Smo), which can acquire mutations causing drug resistance. Thus, compounds that inhibit Hh signaling downstream of Smo are urgently needed. We identified dynarrestin, a novel inhibitor of cytoplasmic dyneins 1 and 2. Dynarrestin acts reversibly to inhibit cytoplasmic dynein 1-dependent microtubule binding and motility invitro without affecting ATP hydrolysis. It rapidly and reversibly inhibits endosome movement in living cells and perturbs mitosis byinducing spindle misorientation and pseudoprometaphase delay. Dynarrestin reversibly inhibitscytoplasmic dynein 2-dependent intraflagellar transport (IFT) of the cargo IFT88 and flux ofSmo within cilia without interfering with ciliogenesis and suppresses Hh-dependent proliferation of neuronal precursors and tumor cells. Assuch, dynarrestin is a valuable tool for probing cytoplasmic dynein-dependent cellular processes and a promising compound for medicinal chemistryprograms aimed at development of anti-cancerdrugs.

Genes and Pathways Regulated by Androgens in Human Neural Cells, Potential Candidates for the Male Excess in Autism Spectrum Disorder

BackgroundPrenatal exposure to androgens during brain development in male individuals may participate to increase their susceptibility to develop neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability. However, little is known about the action of androgens in human neural cells. MethodsWe used human neural stem cells differentiated from embryonic stem cells to investigate targets of androgens. ResultsRNA sequencing revealed that treatment with dihydrotestosterone (DHT) leads to subtle but significant changes in the expression of about 200 genes, encoding proteins of extracellular matrix or involved in signal transduction of growth factors (e.g., insulin/insulin growth factor 1). We showed that the most differentially expressed genes (DEGs), RGCC, RNF144B, NRCAM, TRIM22, FAM107A, IGFBP5, and LAMA2, are reproducibly regulated by different androgens in different genetic backgrounds. We showed, by overexpressing the androgen receptor in neuroblastoma cells SH-SY5Y or knocking it down in human neural stem cells, that this regulation involves the androgen receptor. A chromatin immunoprecipitation combined with direct sequencing analysis identified androgen receptor–bound sequences in nearly half of the DHT-DEGs and in numerous other genes. DHT-DEGs appear enriched in genes involved in ASD (ASXL3, NLGN4X, etc.), associated with ASD (NRCAM), or differentially expressed in patients with ASD (FAM107A, IGFBP5). Androgens increase human neural stem cell proliferation and survival in nutrient-deprived culture conditions, with no detectable effect on regulation of neurite outgrowth. ConclusionsWe characterized androgen action in neural progenitor cells, identifying DHT-DEGs that appear to be enriched in genes related to ASD. We also showed that androgens increase proliferation of neuronal precursors and protect them from death during their differentiation in nutrient-deprived conditions.

Lack Of Endogenous Tau Rescues Impaired Adult Neurogenesis In The Dentate Gyrus In FTLD-17 Human Mutant Tau Transgenic Mice

Lack Of Endogenous Tau Rescues Impaired Adult Neurogenesis In The Dentate Gyrus In FTLD-17 Human Mutant Tau Transgenic Mice

Primary Cilia in the Murine Cerebellum and in Mutant Models of Medulloblastoma.

Cellular primary cilia crucially sense and transduce extracellular physicochemical stimuli. Cilium-mediated developmental signaling is tissue and cell type specific. Primary cilia are required for cerebellar differentiation and sonic hedgehog (Shh)-dependent proliferation of neuronal granule precursors. The mammalian G-protein-coupled receptor 37-like 1 is specifically expressed in cerebellar Bergmann glia astrocytes and participates in regulating postnatal cerebellar granule neuron proliferation/differentiation and Bergmann glia and Purkinje neuron maturation. The mouse receptor protein interacts with the patched 1 component of the cilium-associated Shh receptor complex. Mice heterozygous for patched homolog 1 mutations, like heterozygous patched 1 humans, have a higher incidence of Shh subgroup medulloblastoma (MB) and other tumors. Cerebellar cells bearing primary cilia were identified during postnatal development and in adulthood in two mouse strains with altered Shh signaling: a G-protein-coupled receptor 37-like 1 null mutant and an MB-susceptible, heterozygous patched homolog 1 mutant. In addition to granule and Purkinje neurons, primary cilia were also expressed by Bergmann glia astrocytes in both wild-type and mutant animals, from birth to adulthood. Variations in ciliary number and length were related to the different levels of neuronal and glial cell proliferation and maturation, during postnatal cerebellar development. Primary cilia were also detected in pre-neoplastic MB lesions in heterozygous patched homolog 1 mutant mice and they could represent specific markers for the development and analysis of novel cerebellar oncogenic models.