Number Of Neural Progenitor Cells Research Articles

High Concentrations of Cannabidiol Induce Neurotoxicity in Neurosphere Culture System.

Recent studies have demonstrated that cannabinoids are potentially effective in the treatment of various neurological conditions, and cannabidiol (CBD), one of the most studied compounds, has been proposed as a non-toxic option. However, the adverse effects of CBD on neurodevelopmental processes have rarely been studied in cell culture systems. To better understand CBD's influence on neurodevelopment, we exposed neural progenitor cells (NPCs) to different concentrations of CBD (1µM, 5µM, and 10µM). We assessed the morphology, migration, differentiation, cell death, and gene expression in 2D and 3D bioprinted models to stimulate physiological conditions more effectively. Our results showed that CBD was more toxic at higher concentrations (5µM and 10µM) and affected the viability of NPCs than at lower concentrations (1µM), in both 2D and 3D models. Moreover, our study revealed that higher concentrations of CBD drastically reduced the size of neurospheres and the number of NPCs within neurospheres, impaired the morphology and mobility of neurons and astrocytes after differentiation, and reduced neurite sprouting. Interestingly, we also found that CBD alters cellular metabolism by influencing the expression of glycolytic and β-oxidative enzymes in the early and late stages of metabolic pathways. Therefore, our study demonstrated that higher concentrations of CBD promote important changes in cellular functions that are crucial during CNS development.

Neural cell isolation from adult macaques for high-throughput analyses and neurosphere cultures.

The low number of neural progenitor cells (NPCs) present in the adult and aged primate brains represents a challenge for generating high-yield and viable in vitro cultures of primary brain cells. Here we report a step-by-step approach for the fast and reproducible isolation of high-yield and viable primary brain cells, including mature neurons, immature cells and NPCs, from adult and aged macaques. We describe the anesthesia, transcardial perfusion and brain tissue preparation; the subsequent microdissection of the regions of interest and their enzymatic dissociation, leading to the separation of single cells. The cell isolation steps of our protocol can also be used for routine cell culturing, in particular for NPC expansion and differentiation, suitable for studies of hippocampal neurogenesis in the adult macaque brain. The purified primary brain cells are largely free from myelin debris and erythrocytes, paving the way for multiple downstream applications in vitro and in vivo. When combined with single-cell profiling techniques, this approach allows an unbiased and comprehensive mapping of cell states in the adult and aged macaque brain, which is needed to advance our understanding of human cognitive and neurological diseases. The neural cell isolation protocol requires 4 h and a team of four to six users with expertize in primary brain cell isolation to avoid tissue hypoxia during the time-sensitive steps of the procedure.

Oral Exposure to Lead Acetate for 28 Days Reduces the Number of Neural Progenitor Cells but Increases the Number and Synaptic Plasticity of Newborn Granule Cells in Adult Hippocampal Neurogenesis of Young-Adult Rats.

Lead (Pb) causes developmental neurotoxicity. Developmental exposure to Pb acetate (PbAc) induces aberrant hippocampal neurogenesis by increasing or decreasing neural progenitor cell (NPC) subpopulations in the dentate gyrus (DG) of rats. To investigate whether hippocampal neurogenesis is similarly affected by PbAc exposure in a general toxicity study, 5-week-old Sprague-Dawley rats were orally administered PbAc at 0, 4000, and 8000ppm (w/v) in drinking water for 28days. After exposure to 4000 or 8000ppm PbAc, Pb had accumulated in the brains. Neurogenesis was suppressed by 8000ppm PbAc, which was related to decreased number of type-2b NPCs, although number of mature granule cells were increased by both PbAc doses. Gene expression in the 8000ppm PbAc group suggested suppressed NPC proliferation and increased apoptosis resulting in suppressed neurogenesis. PbAc exposure increased numbers of metallothionein-I/II+ cells and GFAP+ astrocytes in the DG hilus, and upregulated Mt1, antioxidant genes (Hmox1 and Gsta5), and Il6 in the DG, suggesting the induction of oxidative stress and neuroinflammation related to Pb accumulation resulting in suppressed neurogenesis. PbAc at 8000ppm also upregulated Ntrk2 and increased the number of CALB2+ interneurons, suggesting the activation of BDNF-TrkB signaling and CALB2+ interneuron-mediated signals to ameliorate suppressed neurogenesis resulting in increased number of newborn granule cells. PbAc at both doses increased the number of ARC+ granule cells, suggesting the facilitation of synaptic plasticity of newborn granule cells through the activation of BDNF-TrkB signaling. These results suggest that PbAc exposure during the young-adult stage disrupted hippocampal neurogenesis, which had a different pattern from developmental exposure to PbAc. However, the induction of oxidative stress/neuroinflammation and activation of identical cellular signals occurred irrespective of the life stage at PbAc exposure.

Functional Cooperation of α-Synuclein and Tau Is Essential for Proper Corticogenesis.

Alpha-synuclein (αSyn) and tau are abundant multifunctional neuronal proteins, and their intracellular deposits have been linked to many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Despite the disease relevance, their physiological roles remain elusive, as mice with knock-out of either of these genes do not exhibit overt phenotypes. To reveal functional cooperation, we generated αSyn-/-tau-/- double-knock-out mice and characterized the functional cross talk between these proteins during brain development. Intriguingly, deletion of αSyn and tau reduced Notch signaling and accelerated interkinetic nuclear migration of G2 phase at early embryonic stage. This significantly altered the balance between the proliferative and neurogenic divisions of progenitor cells, resulting in an overproduction of early born neurons and enhanced neurogenesis, by which the brain size was enlarged during the embryonic stage in both sexes. On the other hand, a reduction in the number of neural progenitor cells in the middle stage of corticogenesis diminished subsequent gliogenesis in the αSyn-/-tau-/- cortex. Additionally, the expansion and maturation of macroglial cells (astrocytes and oligodendrocytes) were suppressed in the αSyn-/-tau-/- postnatal brain, which in turn reduced the male αSyn-/-tau-/- brain size and cortical thickness to less than the control values. Our study identifies important functional cooperation of αSyn and tau during corticogenesis.SIGNIFICANCE STATEMENT Correct understanding of the physiological functions of αSyn and tau in CNS is critical to elucidate pathogenesis involved in the etiology of neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. We show here that αSyn and tau are cooperatively involved in brain development via maintenance of progenitor cells. αSyn and tau double-knock-out mice exhibited an overproduction of early born neurons and accelerated neurogenesis at early corticogenesis. Furthermore, loss of αSyn and tau also perturbed gliogenesis at later embryonic stage, as well as the subsequent glial expansion and maturation at postnatal brain. Our findings provide new mechanistic insights and extend therapeutic opportunities for neurodegenerative diseases caused by aberrant αSyn and tau.

EP172: A new and milder case of primary autosomal recessive microcephaly type 16

The ANKLE2 gene is located at the 12q24.33 cytogenetic band and encodes a 938 amino acid long protein with a molecular mass of ∼ 10,000 Da. The protein is a mitotic regulator and is important in early brain development. Deficiency of ANKLE2 gene product is associated with reduced mitosis, decreased cell proliferation, increased apoptosis, and diminished numbers of neural progenitor cells. Recently, ANKLE2 interaction with the Zika virus non-structural protein, NS4A, has been hypothesized as the mechanism behind microcephaly in human Zika infections.

Brain-derived neurotrophic factor increases cell number of neural progenitor cells derived from human induced pluripotent stem cells.

BackgroundSeveral pieces of evidence from in vitro studies showed that brain-derived neurotrophic factor (BDNF) promotes proliferation and differentiation of neural stem/progenitor cells (NSCs) into neurons. Moreover, the JAK2 pathway was proposed to be associated with mouse NSC proliferation. BDNF could activate the STAT-3 pathway and induce proliferation in mouse NSCs. However, its effects on proliferation are not fully understood and JAK/STAT pathway was proposed to play a role in this activity.MethodsIn the present study, the effects of BDNF on cell proliferation and neurite outgrowth of Alzheimer’s disease (AD) induced pluripotent stem cells (iPSCs)-derived human neural progenitor cells (hNPCs) were examined. Moreover, a specific signal transduction pathway important in cell proliferation was investigated using a JAK2 inhibitor (AG490) to clarify the role of that pathway.ResultsThe proliferative effect of BDNF was remarkably observed as an increase in Ki-67 positive cells. The cell number of hNPCs was significantly increased after BDNF treatment represented by cellular metabolic activity of the cells measured by MTT assay. This noticeable effect was statistically shown at 20 ng/ml of BDNF treatment. BDNF, however, did not promote neurite outgrowth but increased neuronal cell number. It was found that AG490 suppressed hNPCs proliferation. However, this inhibitor partially decreased BDNF-induced hNPCs proliferation. These results demonstrated the potential role of BDNF for the amelioration of AD through the increase of AD-derived hNPCs number.

Time-course changes in 5-fluorouracil-induced neural progenitor cell damages in the developing rat brain.

5-Fluorouracil (5-Fu) is a DNA-damaging agent and teratogenic in rodents. This study aimed to investigate its influence on neural progenitor cells (NPCs) in the developing fetal rat brain. Dams were intraperitoneally injected with 5-Fu (50 mg/kg b.w.) on gestation day 13 and its effects on fetal NPCs were observed from 3 to 72 hours after treatment (HAT), via periodic examination at six intervals. In NPCs of the fetal brain, the p53-labeling index (LI%) was markedly elevated at 3 HAT. Pyknosis and cleaved caspase-3-LI% also increased at 3 HAT, reaching peak values at 9 and 12 HAT. These parallel changes suggested the induction of apoptosis through a p53-mediated pathway. Pyknotic NPCs were distributed across the ventricular zone (VZ) of the telencephalic wall until 12 HAT, and became localized in the medial and dorsal layers at 12 and 48 HAT. Significant decreases in the numbers of mitotic NPCs and BrdU-LI% were noted from 3 HAT and 24 HAT, respectively. BrdU-positive NPCs were located in the ventral and middle layer at 24 and 48 HAT. p21-positive cells were detected at 12 and 24 HAT. The present results demonstrated that p53-mediated apoptosis was induced in all phases of the cell cycle of the NPCs in the early stage after 5-FU treatment. Furthermore, apoptosis of NPCs and suppression of cell proliferative activity are the events that take place in parallel leading to prominent reduction in the width of the telencephalic wall.

Cell-extrinsic requirement for sulfate in regulating hippocampal neurogenesis.

ABSTRACTSulfate is a key anion required for a range of physiological functions within the brain. These include sulfonation of extracellular proteoglycans to facilitate local growth factor binding and to regulate the shape of morphogen gradients during development. We have previously shown that mice lacking one allele of the sulfate transporter Slc13a4 exhibit reduced sulfate transport into the brain, deficits in social behaviour, reduced performance in learning and memory tasks, and abnormal neurogenesis within the ventricular/subventricular zone lining the lateral ventricles. However, whether these mice have deficits in hippocampal neurogenesis was not addressed. Here, we demonstrate that adult Slc13a4+/− mice have increased neurogenesis within the subgranular zone (SGZ) of the hippocampal dentate gyrus, with elevated numbers of neural progenitor cells and intermediate progenitors. In contrast, by 12 months of age there were reduced numbers of neural stem cells in the SGZ of heterozygous mice. Importantly, we did not observe any changes in proliferation when we isolated and cultured progenitors in vitro in neurosphere assays, suggestive of a cell-extrinsic requirement for sulfate in regulating hippocampal neurogenesis. Collectively, these data demonstrate a requirement for sulfate transport during postnatal brain development to ensure normal adult hippocampal neurogenesis.

The Neuronal Regeneration of Adult Zebrafish After Spinal Cord Injury Is Enhanced by Transplanting Optimized Number of Neural Progenitor Cells

Cell transplantation is commonly used to study the regeneration and repair of the nervous system in animals. However, a technical platform used to evaluate the optimum number of transplanted cells in the recipient’s spinal cord is little reported. Therefore, to develop such platform, we used a zebrafish model, which has transparent embryos, and transgenic line huORFZ, which generates green fluorescent protein (GFP)-expressing cells in the central nervous system under hypoxic stress. After GFP-expressing cells, also termed as hypoxia-responsive recovering cells, were obtained from hypoxia-exposed huORFZ embryos, we transplanted these GFP-(+) cells into the site of spinal cord injury (SCI) in adult wild-type zebrafish, followed by assessing the relationship between number of transplanted cells and the survival rate of recipients. When 100, 300, 500, and 1,000 GFP-(+) donor cells were transplanted into the lesion site of SCI-treated recipients, we found that recipient adult zebrafish transplanted with 300 donor cells had the highest survival rate. Those GFP-(+) donor cells could undergo proliferation and differentiation into neuron in recipients. Furthermore, transplantation of GFP-(+) cells into adult zebrafish treated with SCI was able to enhance the neuronal regeneration of recipients. In contrast, those fish transplanted with over 500 cells showed signs of inflammation around the SCI site, resulting in higher mortality. In this study, we developed a technological platform for transplanting cells into the lesion site of SCI-treated adult zebrafish and defined the optimum number of successfully transplanted cells into recipients, as 300, and those GFP-(+) donor cells could enhance recipient’s spinal cord regeneration. Thus, we provided a practical methodology for studying cell transplantation therapy in neuronal regeneration of zebrafish after SCI.

Sex-specific neurogenic deficits and neurocognitive disorders in middle-aged HIV-1 Tg26 transgenic mice

Varying degrees of cognitive deficits affect over half of all HIV-1 infected patients. Because of antiretroviral treatment (ART) regimens, the HIV-1 patient population is increasing in age. Very few epidemiological studies have focused on sex-specific differences in HIV-1-associated neurocognitive disorders (HAND). The purpose of this study is to examine any possible differences between male and female mice in the progression of cognitive dementia during persistent low-level HIV-1 protein exposure, mimicking the typical clinical setting in the post-ART era. Eight to ten-month old HIV-1 Tg26(+/−) transgenic mice were utilized to assess for specific learning and memory modalities. Initial physiological screening and fear conditioning assessments revealed that Tg26 mice exhibited no significant differences in general behavioral function, contextual fear conditioning, or cued fear conditioning responses when compared to their wild-type (WT) littermates, regardless of sex. However, Barnes maze testing revealed significantly impaired short and long-term spatial memory in males, while females had impaired spatial learning abilities and short-term spatial memory. The potential cellular mechanism underlying these sex-specific neurocognitive deficits was explored with hippocampal neurogenic analysis. Compared to WT mice, both male and female Tg26(+/−) mice had fewer quiescent neural stem cells and neuroblasts in their hippocampi. Male Tg26(+/−) mice had a more robust reduction of the quiescent neural stem cell pool than female Tg26(+/−) mice. While female WT mice had a higher number of neural progenitor cells than male WT mice, only female Tg26(+/−) mice exhibited a robust reduction in the number of neural progenitor cells. Altogether, these results suggest that middle-aged male and female Tg26(+/−) mice manifest differing impairments in cognitive functioning and hippocampal neurogenesis. This study emphasizes the importance of understanding sex related differences in HAND pathology, which would aid in designing more optimized therapeutic regimens for the treatment of HAND.

Matrix Remodeling Enhances the Differentiation Capacity of Neural Progenitor Cells in 3D Hydrogels.

Neural progenitor cells (NPCs) are a promising cell source to repair damaged nervous tissue. However, expansion of therapeutically relevant numbers of NPCs and their efficient differentiation into desired mature cell types remains a challenge. Material‐based strategies, including culture within 3D hydrogels, have the potential to overcome these current limitations. An ideal material would enable both NPC expansion and subsequent differentiation within a single platform. It has recently been demonstrated that cell‐mediated remodeling of 3D hydrogels is necessary to maintain the stem cell phenotype of NPCs during expansion, but the role of matrix remodeling on NPC differentiation and maturation remains unknown. By culturing NPCs within engineered protein hydrogels susceptible to degradation by NPC‐secreted proteases, it is identified that a critical amount of remodeling is necessary to enable NPC differentiation, even in highly degradable gels. Chemical induction of differentiation after sufficient remodeling time results in differentiation into astrocytes and neurotransmitter‐responsive neurons. Matrix remodeling modulates expression of the transcriptional co‐activator Yes‐associated protein, which drives expression of NPC stemness factors and maintains NPC differentiation capacity, in a cadherin‐dependent manner. Thus, cell‐remodelable hydrogels are an attractive platform to enable expansion of NPCs followed by differentiation of the cells into mature phenotypes for therapeutic use.

Deficiency of the clock gene Bmal1 affects neural progenitor cell migration

We demonstrate the impact of a disrupted molecular clock in Bmal1-deficient (Bmal1−/−) mice on migration of neural progenitor cells (NPCs). Proliferation of NPCs in rostral migratory stream (RMS) was reduced in Bmal1−/− mice, consistent with our earlier studies on adult neurogenesis in hippocampus. However, a significantly higher number of NPCs from Bmal1−/− mice reached the olfactory bulb as compared to wild-type littermates (Bmal1+/+ mice), indicating a higher migration velocity in Bmal1−/− mice. In isolated NPCs from Bmal1−/− mice, not only migration velocity and expression pattern of genes involved in detoxification of reactive oxygen species were affected, but also RNA oxidation of catalase was increased and catalase protein levels were decreased. Bmal1+/+ migration phenotype could be restored by treatment with catalase, while treatment of NPCs from Bmal1+/+ mice with hydrogen peroxide mimicked Bmal1−/− migration phenotype. Thus, we conclude that Bmal1 deficiency affects NPC migration as a consequence of dysregulated detoxification of reactive oxygen species.

UTX Affects Neural Stem Cell Proliferation and Differentiation through PTEN Signaling.

SummaryNeural stem cell (NSC) proliferation and differentiation in the developing brain is a complex process precisely regulated by intrinsic and extrinsic signals. Although epigenetic modification has been reportedly involved in the regulation of the cerebral cortex, whether UTX, an H3K27me3 demethylase, regulates the development of cerebral cortex during the embryonic period is unclear. In this study, we demonstrate that Utx deficiency by knockdown and conditional knockout increases NSC proliferation and decreases terminal mitosis and neuronal differentiation. Furthermore, we find that impairment of cortical development caused by lack of Utx is less significant in males than in females. In addition, UTX demethylates H3K27me3 at the Pten promoter and promotes Pten expression. P-AKT and P-mTOR levels are increased in the Utx conditional knockout cortices. Finally, Utx or Pten overexpression can rescue the impairment of brain development caused by Utx loss. These findings may provide important clues toward deciphering brain diseases.

Mechano growth factor, a splice variant of IGF-1, promotes neurogenesis in the aging mouse brain

Mechano growth factor (MGF) is a splice variant of IGF-1 first described in skeletal muscle. MGF induces muscle cell proliferation in response to muscle stress and injury. In control mice we found endogenous expression of MGF in neurogenic areas of the brain and these levels declined with age. To better understand the role of MGF in the brain, we used transgenic mice that constitutively overexpressed MGF from birth. MGF overexpression significantly increased the number of BrdU+ proliferative cells in the dentate gyrus (DG) of the hippocampus and subventricular zone (SVG). Although MGF overexpression increased the overall rate of adult hippocampal neurogenesis at the proliferation stage it did not alter the distribution of neurons at post-mitotic maturation stages. We then used the lac-operon system to conditionally overexpress MGF in the mouse brain beginning at 1, 3 and 12 months with histological and behavioral observation at 24 months of age. With conditional overexpression there was an increase of BrdU+ proliferating cells and BrdU+ differentiated mature neurons in the olfactory bulbs at 24 months when overexpression was induced from 1 and 3 months of age but not when started at 12 months. This was associated with preserved olfactory function. In vitro, MGF increased the size and number of neurospheres harvested from SVZ-derived neural stem cells (NSCs). These findings indicate that MGF overexpression increases the number of neural progenitor cells and promotes neurogenesis but does not alter the distribution of adult newborn neurons at post-mitotic stages. Maintaining youthful levels of MGF may be important in reversing age-related neuronal loss and brain dysfunction.

Anterior-Posterior Gradient in Neural Stem and Daughter Cell Proliferation Governed by Spatial and Temporal Hox Control

A readily evident feature of animal central nervous systems (CNSs), apparent in all vertebrates and many invertebrates alike, is its "wedge-like" appearance, with more cells generated in anterior than posterior regions. This wedge could conceivably be established by an antero-posterior (A-P) gradient in the number of neural progenitor cells, their proliferation behaviors, and/or programmed cell death (PCD). However, the contribution of each of these mechanisms, and the underlying genetic programs, are not well understood. Building upon recent progress in the Drosophila melanogaster (Drosophila) ventral nerve cord (VNC), we address these issues in acomprehensive manner. We find that, although PCD plays a role in controlling cell numbers along the A-P axis, the main driver of the wedge is a gradient of daughter proliferation, with divisions directly generating neurons (type 0) being more prevalent posteriorly and dividing daughters (type I) more prevalent anteriorly. In addition, neural progenitor (NB) cell-cycle exit occurs earlier posteriorly. The gradient of type I > 0 daughter proliferation switch and NB exit combine to generate radically different average lineage sizes along the A-P axis, differing by more than 3-fold in cell number. We find that theHox homeotic genes, expressed in overlapping A-P gradients and with a late temporal onset in NBs, trigger the type I > 0 daughter proliferation switch and NB exit. Given the highly evolutionarily conserved expression of overlapping Hox homeotic genes in the CNS, our results point to a common mechanism for generating the CNS wedge.

Administration of Zinc plus Cyclo-(His-Pro) Increases Hippocampal Neurogenesis in Rats during the Early Phase of Streptozotocin-Induced Diabetes.

The effects of zinc supplementation on hippocampal neurogenesis in diabetes mellitus have not been studied. Herein, we investigated the effects of zinc plus cyclo-(His-Pro) (ZC) on neurogenesis occurring in the subgranular zone of dentate gyrus after streptozotocin (STZ)-induced diabetes. ZC (27 mg/kg) was administered by gavage once daily for one or six weeks from the third day after the STZ injection, and histological evaluation was performed at 10 (early phase) or 45 (late phase) days after STZ injection. We found that the proliferation of progenitor cells in STZ-induced diabetic rats showed an increase in the early phase. Additionally, ZC treatment remarkably increased the number of neural progenitor cells (NPCs) and immature neurons in the early phase of STZ-induced diabetic rats. Furthermore, ZC treatment showed increased survival rate of newly generated cells but no difference in the level of neurogenesis in the late phase of STZ-induced diabetic rats. The present study demonstrates that zinc supplementation by ZC increases both NPCs proliferation and neuroblast production at the early phase of diabetes. Thus, this study suggests that zinc supplemented with a histidine/proline complex may have beneficial effects on neurogenesis in patients experiencing the early phase of Type 1 diabetes.

Helios expression coordinates the development of a subset of striatopallidal medium spiny neurons.

Here, we unravel the mechanism of action of the Ikaros family zinc finger protein Helios (He) during the development of striatal medium spiny neurons (MSNs). He regulates the second wave of striatal neurogenesis involved in the generation of striatopallidal neurons, which express dopamine 2 receptor and enkephalin. To exert this effect, He is expressed in neural progenitor cells (NPCs) keeping them in the G1/G0 phase of the cell cycle. Thus, a lack of He results in an increase of S-phase entry and S-phase length of NPCs, which in turn impairs striatal neurogenesis and produces an accumulation of the number of cycling NPCs in the germinal zone (GZ), which end up dying at postnatal stages. Therefore, He−/− mice show a reduction in the number of dorso-medial striatal MSNs in the adult that produces deficits in motor skills acquisition. In addition, overexpression of He in NPCs induces misexpression of DARPP-32 when transplanted in mouse striatum. These findings demonstrate that He is involved in the correct development of a subset of striatopallidal MSNs and reveal new cellular mechanisms for neuronal development.

Immune Regulator MCPIP1 Modulates TET Expression during Early Neocortical Development.

SummaryMCPIP1 is a recently identified immune regulator that plays critical roles in preventing immune disorders, and is also present in the brain. Currently an unresolved question remains as to how MCPIP1 performs its non-immune functions in normal brain development. Here, we report that MCPIP1 is abundant in neural progenitor cells (NPCs) and newborn neurons during the early stages of neurogenesis. The suppression of MCPIP1 expression impairs normal neuronal differentiation, cell-cycle exit, and concomitant NPC proliferation. MCPIP1 is important for maintenance of the NPC pool. Notably, we demonstrate that MCPIP1 reduces TET (TET1/TET2/TET3) levels and then decreases 5-hydroxymethylcytosine levels. Furthermore, the MCPIP1 interaction with TETs is involved in neurogenesis and in establishing the proper number of NPCs in vivo. Collectively, our findings not only demonstrate that MCPIP1 plays an important role in early cortical neurogenesis but also reveal an unexpected link between neocortical development, immune regulators, and epigenetic modification.

Mcm3 replicative helicase mutation impairs neuroblast proliferation and memory in Drosophila.

In the developing Drosophila brain, a small number of neural progenitor cells (neuroblasts) generate in a co-ordinated manner a high variety of neuronal cells by integration of temporal, spatial and cell-intrinsic information. In this study, we performed the molecular and phenotypic characterization of a structural brain mutant called small mushroom bodies (smu), which was isolated in a screen for mutants with altered brain structure. Focusing on the mushroom body neuroblast lineages we show that failure of neuroblasts to generate the normal number of mushroom body neurons (Kenyon cells) is the major cause of the smu phenotype. In particular, the premature loss of mushroom body neuroblasts caused a pronounced effect on the number of late-born Kenyon cells. Neuroblasts showed no obvious defects in processes controlling asymmetric cell division, but generated less ganglion mother cells. Cloning of smu uncovered a single amino acid substitution in an evolutionarily conserved protein interaction domain of the Minichromosome maintenance 3 (Mcm3) protein. Mcm3 is part of the multimeric Cdc45/Mcm/GINS (CMG) complex, which functions as a helicase during DNA replication. We propose that at least in the case of mushroom body neuroblasts, timely replication is not only required for continuous proliferation but also for their survival. The absence of Kenyon cells in smu reduced learning and early phases of conditioned olfactory memory. Corresponding to the absence of late-born Kenyon cells projecting to α'/β' and α/β lobes, smu is profoundly defective in later phases of persistent memory.

Lentivirus‐Mediated Overexpression of MicroRNA‐210 Improves Long‐Term Outcomes after Focal Cerebral Ischemia in Mice

MicroRNAs play an important role in the pathogenesis of ischemic brain injury and in the repair process during postischemic condition. However, the key miRNAs and their function in these processes remain unclear. Circulating blood MicroRNAs profiles were examined in the ischemic stroke patients. The predicted network of difference was analyzed by ingenuity pathway analysis. The key MicroRNAs were selected, and the function was further studied in a mouse ischemia model. The predicted downstream target was confirmed. We found that 24 MicroRNAs were differently expressed in stroke patients compared to the control (P < 0.05). Bioinformatic analysis showed a MicroRNAs regulated network with the highest score in the stroke cascade, which was consisted of 10 MicroRNAs including key hypoxia-related miR-210 and its predicted downstream target brain derived neurotrophic factor (BDNF). Lentivirus-mediated miR-210 overexpression enhanced the microvessel density and the number of neural progenitor cells in the ischemic mouse brain (P < 0.05) and improved neurobehavioral outcomes in the ischemic mouse (P < 0.05). MiR-210 upregulation increased mBDNF/proBDNF protein expression in the normal and ischemic mouse brain. The dual-luciferase reporter assay identified that BDNF was the direct target of miR-210. MiR-210 is a crucial ischemic stroke-associated MicroRNAs and a potential target for the stroke therapy.