Effects of Cu,Zn-Superoxide Dismutase on Cell Proliferation and Neuroblast Differentiation in the Mouse Dentate Gyrus

Oxidative stress is one of the most important factors in reducing adult hippocampal neurogenesis in the adult brain. In this study, we observed the effects of Cu,Zn-superoxide dismutase (SOD1) on lipid peroxidation, cell proliferation, and neuroblast differentiation in the mouse dentate gyrus using malondialdehyde (MDA), Ki67, and doublecortin (DCX), respectively. We constructed an expression vector, PEP-1, fused PEP-1 with SOD1, and generated PEP-1-SOD1 fusion protein. We administered PEP-1 and 100 or 500 μg PEP-1-SOD1 intraperitoneally once a day for 3 weeks and sacrificed at 30 min after the last administrations. PEP-1 administration did not change the MDA levels compared to those in the vehicle-treated group, while PEP-1-SOD1 treatment significantly reduced MDA levels compared to the vehicle-treated group. In the PEP-1-treated group, the number of Ki67-positive nuclei was similar to that in the vehicle-treated group. In the 100 μg PEP-1-SOD1-treated group, the number of Ki67-positive nuclei was slightly decreased; however, in the 500 μg PEP-1-SOD1-treated group, Ki67-positive nuclei were decreased to 78.5% of the vehicle-treated group. The number of DCX-positive neuroblasts in the PEP-1-treated group was similar to that in the vehicle-treated group. However, the arborization of DCX-positive neuroblasts was significantly decreased in both the 100 and 500 μg PEP-1-SOD1-treated groups compared to that in the vehicle-treated group. The number of DCX-positive neuroblasts with tertiary dendrites was markedly decreased in the 500 μg PEP-1-SOD1-treated group. These results suggest that a SOD1 supplement to healthy mice may not be necessary to modulate cell proliferation and neuroblast differentiation in the dentate gyrus.     

Pyridoxine Enhances Cell Proliferation and Neuroblast Differentiation by Upregulating the GABAergic System in the Mouse Dentate Gyrus

We investigated the effects of pyridoxine (vitamin B₆) on cell death, cell proliferation, neuroblast differentiation, and the GABAergic system in the mouse dentate gyrus. We administered pyridoxine (350 mg/kg intraperitoneally) to 8 week old mice twice a day for 14 days and sacrificed them at 10 weeks of age. Pyridoxine treatment did not induce neuronal death or activate microglia in the dentate gyrus, while glial fibrillary acidic protein (GFAP)-positive cells were significantly increased in the subgranular zone of the dentate gyrus. The increase in GFAP-positive cells was confirmed to be due to proliferating cells based on double immunofluorescence staining. GFAP-positive cells, which were also labeled with Ki67, a marker for cell proliferation, and doublecortin, a marker for neuroblast differentiation, were significantly increased in the pyridoxine-treated group compared to those in the vehicle-treated group. Pyridoxine treatment also increased the protein levels of glutamic acid decarboxylase (GAD) 67, an enzyme for GABA synthesis, and pyridoxal 5′-phosphate (PNP) oxidase, an enzyme for pyridoxal phosphate synthesis, in the dentate gyrus. These results suggest that pyridoxine treatment distinctly increases cell proliferation, neuroblast differentiation, and upregulated the GABAergic system, as revealed by the increases of GAD67 and PNP oxidase in the mouse dentate gyrus.     

Metformin Normalizes Type 2 Diabetes-Induced Decrease in Cell Proliferation and Neuroblast Differentiation in the Rat Dentate Gyrus

In this study, we observed the effects of metformin, one of the most widely prescribed drugs for the treatment of type 2 diabetes, on cell proliferation and neuroblast differentiation in the subgranular zone of the hippocampal dentate gyrus (SZDG) in Zucker diabetic fatty (ZDF) rats, which are a model for type 2 diabetes. For this, metformin was administered orally once a day to 14-week-old ZDF rats for 2 weeks and the animals were sacrificed at 16 weeks of age. During this period, blood glucose levels were higher in the vehicle-treated ZDF rats than in the Zucker lean control (ZLC) rats. Metformin treatment significantly decreased the blood glucose levels from 15.5 weeks of age. In the SZDG, Ki67 (a marker for cell proliferation)- and doublecortin (DCX, a marker for differentiated neuroblasts)-immunoreactive cells were much lower in the vehicle-treated ZDF rats than in the ZLC rats. In the metformin-treated ZDF group, Ki67- and DCX-immunoreactive cells were significantly increased in the SZDG compared to those in the vehicle-treated ZDF group. These results suggest that diabetes significantly reduces cell proliferation and neuroblast differentiation in the SZDG and that metformin treatment normalizes the reduction of cell proliferation and neuroblast differentiation in the SZDG in diabetic rats.     

Effects of Sensitive to Apoptosis Gene Protein on Cell Proliferation, Neuroblast Differentiation, and Oxidative Stress in the Mouse Dentate Gyrus

Sensitive to apoptosis gene (SAG) protein is a redox-inducible protein that protects cells against apoptosis induced by redox agents. In this study, we observed effects of SAG on cell proliferation and neuroblast differentiation in the mouse hippocampal dentate gyrus (DG) using Ki67 and doublecortin (DCX), respectively. For easy penetration into neurons, Tat-SAG expression vector was constructed by ligation with SAG and expression vector, Tat, in-frame with six histidine open-reading frames to generate the expression vector, and cloned into E. coli DH5α cells. One or 5?mg/kg Tat-SAG fusion protein (Tat-SAG) was intraperitoneally administered to mice once a day for 3?weeks. The administration of Tat-SAG significantly increased the number of 5-bromodeoxyuridine positive cells, Ki67 positive cells and DCX immunoreactive neuroblast in the mouse DG: Especially, in the 5?mg/kg Tat-SAG-treated mice, DCX positive neuroblasts showed a well-developed arborization of tertiary dendrites in the DG. On the other hand, we examined that the administration of Tat-SAG significantly reduced the DNA damage and lipid peroxidation judging from 8-hydroxy-2'-deoxyguanosine and 4-hydroxynonenal immunohistochemistry: The decrease was much more distinct in the 5?mg/kg Tat-SAG-treated mice than 1?mg/kg Tat-SAG-treated mice. This result suggests that SAG significantly increases cell proliferation, neuroblast differentiation and oxidative stress in normal states.     

Cell Proliferation and Neuroblast Differentiation in the Rat Dentate Gyrus After Intrathecal Treatment with Adipose-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) have emerged as a new therapeutic tool for a number of clinical applications, because they have multipotency and paracrine effects via various factors. In the present study, we investigated the effects of adipose-derived MSC (Ad-MSC) transplantation via intrathecal injection through the cisterna magna on cell proliferation and differentiation of endogenous stem cells in the hippocampal dentate gyrus (DG) using Ki-67 (a marker for proliferating cells), and doublecortin (DCX, a marker for neuroblasts). The transplanted Ad-MSC were detected in the meninges, not in the hippocampal parenchyma. However, the number of Ki-67-immunoreactive cells was significantly increased by 83% in the DG 2 days after single Ad-MSC injection, and by 67% at 23 days after repeated Ad-MSC treatment compared with that in the vehicle-treated group after Ad-MSC transplantation. On the other hand, the number of DCX-immunoreactive cells in the DG was not changed at 2 days after single Ad-MSC injection; however, it was significantly increased by 62% 9 days after single Ad-MSC injection. At 23 days after repeated Ad-MSC application, the number of DCX-immunoreactive cells was much more increased (223% of the vehicle-treated group). At this time point, DCX protein levels were also significantly increased compared with those in the vehicle-treated group. These results suggest that the intrathecal injection of Ad-MSC could enhance endogenous cell proliferation, and the repeated Ad-MSC injection could be more efficient for an enhancement of endogenous cell proliferation and differentiation in the brain.     

Effects of Adrenalectomy and Replacement Therapy of Corticosterone on Cell Proliferation and Neuroblast Differentiation in the Rat Dentate Gyrus

Newly generated neurons in the dentate gyrus differentiate into mature granule cells. In the present study, we observed the effects of adrenalectomy (ADX) and corticosterone replacement therapy (CRT) on cell death, cell proliferation and neuroblast differentiation in the subgranular zone of the hippocampal dentate gyrus (SZDG). For this, the animals received vehicle or CRT after ADX, and were sacrificed 5 or 42 days later. Plasma corticosterone levels were very low in the adrenalectomized groups, whereas CRT after ADX significant increased serum corticosterone levels at 42 days, not 5 days, after ADX. ADX induced some neuronal damage in the dentate gyrus at 5 days post-ADX. CRT did not significantly reduce the neuronal damage at 5 days post-ADX; however, neuronal damage was not shown at 42 post-ADX with CRT. Ki67 (a marker for cell proliferation) and doublecortin (DCX, a marker for neuronal differentiation) immunoreaction was detected in the SZDG. ADX transiently increased cell proliferation and neuroblast differentiation 5 days after ADX, not 42 days, after ADX, and the CRT 42 days after ADX prominently decreased cell proliferation and neuroblast differentiation in the dentate gyrus. These results suggest that adrenal corticosteroid hormone is not essential for cell proliferation and neuroblast differentiation in long-term period after ADX.     

Stem- and Progenitor Cell Proliferation in the Dentate Gyrus of the Reeler Mouse

Adult hippocampal neurogenesis has been implicated in hippocampus-dependent learning and memory. Furthermore, the decline of neurogenesis accompanying aging could be involved in age-related cognitive deficits. It is believed that the neural stem cell niche comprises a specialized microenvironment regulating stem cell activation and maintenance. However, little is known about the significance of the extracellular matrix in controlling adult stem cells. Reelin is a large glycoprotein of the extracelluar matrix known to be of crucial importance for neuronal migration. Here, we examined the local interrelation between Reelin expressing interneurons and putative hippocampal stem cells and investigated the effects of Reelin deficiency on stem cell and progenitor cell proliferation. Reelin-positive cells are found in close vicinity to putative stem cell processes, which would allow for stem cell regulation by Reelin. We investigated the proliferation of stem cells in the Reelin-deficient reeler hippocampus by Ki67 labeling and found a strong reduction of mitotic cells. A detailed analysis of dividing Type 1, type 2 and type 3 cells indicated that once a stem cell is recruited for proliferation, the progression to the next progenitor stage as well as the number of mitotic cycles is not altered in reeler. Our data point to a role for Reelin in either regulating stem cell quiescence or maintenance.     

Phosphoglycerate Mutase 1 Promotes Cell Proliferation and Neuroblast Differentiation in the Dentate Gyrus by Facilitating the Phosphorylation of cAMP Response Element-Binding Protein

Neurochemical Research - In a previous study, we observed a significant increase in phosphoglycerate mutase 1 (PGAM1) levels after pyridoxine treatment. In the present study, we investigated the...     

Combination Effects of Sodium Butyrate and Pyridoxine Treatment on Cell Proliferation and Neuroblast Differentiation in the Dentate Gyrus of d-Galactose-Induced Aging Model Mice

We previously reported that sodium butyrate (SB), a histone deacetylase inhibitor, robustly increased pyridoxine-induced cell proliferation and neuroblast differentiation in the dentate gyrus of the adult mouse. In this study, we investigated the effects of treatment with SB combined with pyridoxine on cell proliferation and neuroblast differentiation in the dentate gyrus of a mouse model of aging induced by d-galactose (d-gal). d-gal was administered to 20-week-old male mice (d-gal mice) for 10 weeks to induce changes that resemble natural aging in animals. Seven weeks after d-gal (100 mg/kg) treatment, vehicle (physiological saline; d-gal-vehicle mice) and SB (300 mg/kg) combined with pyridoxine (Pyr; 350 mg/kg) were administered to the mice (d-gal-Pyr-SB mice) for 3 weeks. Escape latency under water maze in the d-gal mice was longer than that in the control mice. In the d-gal-Pyr-SB mice, escape latency was similar to that in the control mice. In the d-gal mice, many cells in the granule cell layer of the dentate gyrus showed pyknosis and condensation of the cytoplasm. However, in the d-gal-Pyr-SB mice, such cellular changes were rarely found. Furthermore, the d-gal mice showed a great reduction in cell proliferation (Ki67-positive cells) and neuroblast differentiation (doublecortin-positive neuroblasts) in the dentate gyrus compared to control mice. However, in the d-gal-Pyr-SB mice, cell proliferation and neuroblast differentiation were markedly increased in the dentate gyrus. Furthermore, the administration of pyridoxine with sodium butyrate significantly increased Ser133-phosphorylated cyclic AMP response element binding protein in the dentate gyrus. These results indicate that the combination treatment of Pyr with SB in d-gal mice ameliorated the d-gal-induced reduction in cell proliferation, neuroblast differentiation, and memory deficits.     

Effects of Treadmill Exercise on Neural Stem Cells, Cell Proliferation, and Neuroblast Differentiation in the Subgranular Zone of the Dentate Gyrus in Cyclooxygenase-2 Knockout Mice

Cyclooxygenase-2 (COX-2) function has been implicated in a number of physiological processes, including inflammatory responses, synaptic transmission, and synaptic plasticity in the brain. However, the specific role of COX-2 in exercise-induced neurogenesis is still debatable. Here, we assessed the role of COX-2 in exercise-induced plasticity by comparing COX-2 knockout mice to wild-type control littermates. We investigated the number of neural stem cells, and the degree of cell proliferation and neuronal differentiation in COX-2 knockout and its wild-type mice that either exercised or remained inactive. Wild-type and COX-2 knockout mice were put on a treadmill and were either sedentary or were forced to run 1 h/day for five consecutive days at a pace of 10–12 m/min for 5 weeks. Loss of COX-2 expression in the knockout mice was confirmed with two measures: (1) COX immunolabeling in the hippocampus, and (2) the identification of abnormal kidney development using hematoxylin and eosin staining, including subcapsular glomerular hypoplasia and hypertrophy of the deeper cortical glomeruli. Compared to wild-type mice, COX-2 knockout mice exhibited a significant reduction in the neural stem cells (nestin-positive cells), cell proliferation (Ki67-positive cells), and neuroblast differentiation (doublecortin-positive cells). In contrast, exercise significantly increased the neural stem cells, cell proliferation, and neuroblast differentiation in both the wild-type and COX-2 knockout mice although the NeuN-immunoreactive neurons were similar in all groups. Expression of phosphorylated cAMP-response element binding protein was decreased in knockout mice. Exercise increased its expression in the subgranular zone of the dentate gyrus in both wild-type and knockout mice. These results suggest that the COX-2 pathway is one of important factors on neural stem cells, cell proliferation and neuroblast differentiation in sedentary mice. The ability of exercise to increase these types of neural plasticity, regardless of COX-2 signaling, suggests that the effects of exercise on neural stem cells, cell proliferation, and neuroblast differentiation are induced via a pathway that is independent of COX-2.     

Additive or Synergistic Effects of Aluminum on the Reduction of Neural Stem Cells, Cell Proliferation, and Neuroblast Differentiation in the Dentate Gyrus of High-Fat Diet-Fed Mice

Aluminum is the most plentiful metal on the Earth’s crust, and its usage in cooking utensils, cosmetics, drinking containers, food additives, pharmaceutical products, and building materials provides many opportunities for potential aluminum consumption. However, its toxicity is low and harmful effects only develop with large-scale deposition of aluminum. In this study, we investigated the effects of subchronic exposure to aluminum (40 mg/kg/day) on neural stem cells, cell proliferation, neuroblast differentiation, and mature neurons in the dentate gyrus of the hippocampus. These experiments were performed in both high-fat diet and low-fat diet-fed C57BL/6J mice via immunohistochemistry using the relevant marker for each cell type, including nestin, Ki67, doublecortin, and NeuN. Subchronic exposure to aluminum in both low-fat and high-fat diet-fed mice reduced neural stem cells, cell proliferation, and neuroblast differentiation without any changes in mature neurons. Furthermore, this reduction effect was exacerbated in high-fat diet-fed mice. These results suggest that aluminum accelerates the reduction of neural stem cells, cell proliferation, and neuroblast differentiation additively or synergistically in high-fat diet-fed mice without any harmful changes in mature neurons.     

Chronic Treatment with the GLP1 Analogue Liraglutide Increases Cell Proliferation and Differentiation into Neurons in an AD Mouse Model

Neurogenesis is a life long process, but the rate of cell proliferation and differentiation decreases with age. In Alzheimer''s patients, along with age, the presence of Aβ in the brain inhibits this process by reducing stem cell proliferation and cell differentiation. GLP-1 is a growth factor that has neuroprotective properties. GLP1 receptors are present on neuronal progenitor cells, and the GLP-1 analogue liraglutide has been shown to increase cell proliferation in an Alzheimer''s disease (AD) mouse model. Here we investigated acute and chronic effects of liraglutide on progenitor cell proliferation, neuroblast differentiation and their subsequent differentiation into neurons in wild type and APP/PS-1 mice at different ages. APP/PS1 and their littermate controls, aged 3, 6, 12, 15 months were injected acutely or chronically with 25 nmol/kg liraglutide. Acute treatment with liraglutide showed an increase in cell proliferation in APP/PS1 mice, but not in controls whereas chronic treatment increased cell proliferation at all ages (BrdU and Ki67 markers). Moreover, numbers of immature neurons (DCX) were increased in both acute and chronic treated animals at all ages. Most newly generated cells differentiated into mature neurons (NeuN marker). A significant increase was observed with chronically treated 6, 12, 15 month APP/PS1 and WT groups. These results demonstrate that liraglutide, which is currently on the market as a treatment for type 2 diabetes (Victoza^TM), increases neurogenesis, which may have beneficial effects in neurodegenerative disorders like AD.     

Aripiprazole, An Atypical Antipsychotic Drug, Improves Maturation and Complexity of Neuroblast Dendrites in the Mouse Dentate Gyrus Via Increasing Superoxide Dismutases

Apripiprazole (APZ) is well known as an atypical antipsychotic and antidepressant. In the present study, we investigated effects of APZ on cell proliferation and neuronal differentiation in the dentate gyrus (DG) of the adolescent mouse using BruU, Ki-67 and doublecortin (DCX) immunohistochemistry. BruU, Ki-67 and DCX-positive (+) cells were easily detected in the subgranular zone of the DG in the vehicle- and APZ-treated group. We found that in the 8 mg/kg APZ-treated group numbers of Ki-67⁺, DCX⁺ and BrdU⁺/DCX⁺ cells were significantly increased compared with those in the vehicle-treated group. We also found that maturation and complexity of DCX⁺ dendrites in the 8 mg/kg APZ-treated group was well improved compared with those in the vehicle-treated group. In addition, markedly decreased lipid peroxidation and increased superoxide dismutase 2 (SOD2) level were observed in the DG of the 8 mg/kg APZ-treated group. Our present findings indicate that APZ can enhance cell proliferation and neuroblast differentiation, particularly maturation and complexity of neuroblast dendrites, in the DG via decreasing lipid peroxidation and increasing SOD2 level.     

Effects of Treadmill Exercise on Cell Proliferation and Differentiation in the Subgranular Zone of the Dentate Gyrus in a Rat Model of Type II Diabetes

In the present study, we investigated the effects of a treadmill exercise on serum glucose levels and Ki67 and doublecortin (DCX) immunoreactivity, which is a marker of cell proliferation expressed during cell cycles except G0 and early G1 and a marker of progenitors differentiating into neurons, respectively, in the subgranular zone of the dentate gyrus (SZDG) using a type II diabetic model. At 6 weeks of age, Zucker lean control (ZLC) and Zucker diabetic fatty (ZDF) rats were put on a treadmill with or without running for 1 h/day/5 consecutive days at 22 m/min for 5 weeks. Body weight was significantly increased in the control (without running)-ZDF rats compared to that in the other groups. In the control groups blood glucose levels were increased by 392.7 mg/dl in the control-ZDF rats and by 143.3 mg/dl in the control-ZLC rats. However, in the exercise groups, blood glucose levels were similar between the exercise-ZLC and ZDF rats: The blood glucose levels were 110.0 and 118.2 mg/dl, respectively. Ki67 positive nuclei were detected in the SZDG in control and exercise groups. The number of Ki67 positive nuclei was significantly high in exercise groups compared to that in the control groups. In addition, Ki67 positive cells were abundant in ZLC groups compared to those in ZDF groups. DCX-immunoreactive structures in the control-ZDF rats were lower than that in the control-ZLC rats. In the exercise groups, DCX-immunoreactive structures (somata and processes with tertiary dendrites) and DCX protein levels were markedly increased in both the exercise-ZLC and ZDF rats compared to that in the control groups. These results suggest that a treadmill exercise reduces blood glucose levels in ZDF rats and increases cell proliferation and differentiation in the SZDG in ZLC and ZDF rats compared to those in control groups.     

应用微重力旋转生物反应器培养小鼠脂肪干细胞的初步实验研究

目的:观察微重力旋转培养系统(Rotary Cell Culture System,RCCS),对小鼠脂肪干细胞增殖的影响,以寻求一种更有效的促进干细胞扩增的方法.方法:从小鼠的脂肪组织中提取分离、培养脂肪干细胞(ADSCs),并对脂肪干细胞进行流式鉴定后,利用活细胞观察法、Dil免疫荧光标记法、扫描电镜法观察微重力旋转三维培养系统对脂肪干细胞增殖的影响;通过与平面二维培养作对比,血小板计数法记录细胞的增殖情况,并绘制生长曲线.结果:两组的细胞倍增时间具有统计学意义(P＜0.05),模拟微重力旋转三维培养系统较传统平面二维培养系统,脂肪干细胞增殖更明显,生长速度更快.结论:模拟微重力旋转三维培养系统更有利于脂肪干细胞的增殖生长,为后期利用脂肪干细胞修复受损涎腺提供一种更快捷有效的扩增方法.     

GATA6 Is Required for Proliferation, Migration, Secretory Cell Maturation, and Gene Expression in the Mature Mouse Colon

Controlled renewal of the epithelium with precise cell distribution and gene expression patterns is essential for colonic function. GATA6 is expressed in the colonic epithelium, but its function in the colon is currently unknown. To define GATA6 function in the colon, we conditionally deleted Gata6 throughout the epithelium of small and large intestines of adult mice. In the colon, Gata6 deletion resulted in shorter, wider crypts, a decrease in proliferation, and a delayed crypt-to-surface epithelial migration rate. Staining techniques and electron microscopy indicated deficient maturation of goblet cells, and coimmunofluorescence demonstrated alterations in specific hormones produced by the endocrine L cells and serotonin-producing cells. Specific colonocyte genes were significantly downregulated. In LS174T, the colonic adenocarcinoma cell line, Gata6 knockdown resulted in a significant downregulation of a similar subset of goblet cell and colonocyte genes, and GATA6 was found to occupy active loci in enhancers and promoters of some of these genes, suggesting that they are direct targets of GATA6. These data demonstrate that GATA6 is necessary for proliferation, migration, lineage maturation, and gene expression in the mature colonic epithelium.     

Synergistic Effects of Sodium Butyrate,a Histone Deacetylase Inhibitor,on Increase of Neurogenesis Induced by Pyridoxine and Increase of Neural Proliferation in the Mouse Dentate Gyrus

We previously observed that pyridoxine (vitamin B₆) significantly increased cell proliferation and neuroblast differentiation without any neuronal damage in the hippocampus. In this study, we investigated the effects of sodium butyrate, a histone deacetylase (HDAC) inhibitor which serves as an epigenetic regulator of gene expression, on pyridoxine-induced neural proliferation and neurogenesis induced by the increase of neural proliferation in the mouse dentate gyrus. Sodium butyrate (300 mg/kg, subcutaneously), pyridoxine (350 mg/kg, intraperitoneally), or combination with sodium butyrate were administered to 8-week-old mice twice a day and once a day, respectively, for 14 days. The administration of sodium butyrate significantly increased acetyl-histone H3 levels in the dentate gyrus. Sodium butyrate alone did not show the significant increase of cell proliferation in the dentate gyrus. But, pyridoxine alone significantly increased cell proliferation. Sodium butyrate in combination with pyridoxine robustly enhanced cell proliferation and neurogenesis induced by the increase of neural proliferation in the dentate gyrus, showing that sodium butyrate treatment distinctively enhanced development of neuroblast dendrites. These results indicate that an inhibition of HDAC synergistically promotes neurogenesis induced by a pyridoxine and increase of neural proliferation.     

Prox1 Inhibits Proliferation and Is Required for Differentiation of the Oligodendrocyte Cell Lineage in the Mouse

Central nervous system injury induces a regenerative response in ensheathing glial cells comprising cell proliferation, spontaneous axonal remyelination, and limited functional recovery, but the molecular mechanisms are not fully understood. In Drosophila, this involves the genes prospero and Notch controlling the balance between glial proliferation and differentiation, and manipulating their levels in glia can switch the response to injury from prevention to promotion of repair. In the mouse, Notch1 maintains NG2 oligodendrocyte progenitor cells (OPCs) in a progenitor state, but what factor may enable oligodendrocyte (OL) differentiation and functional remyelination is not understood. Here, we asked whether the mammalian homologue of prospero, Prox1, is involved. Our data show that Prox1 is distributed in NG2+ OPCs and in OLs in primary cultured cells, and in the mouse spinal cord in vivo. siRNA prox1 knockdown in primary OPCs increased cell proliferation, increased NG2+ OPC cell number and decreased CC1+ OL number. Prox1 conditional knockout in the OL cell lineage in mice increased NG2+ OPC cell number, and decreased CC1+ OL number. Lysolecithin-induced demyelination injury caused a reduction in CC1+ OLs in homozygous Prox1-/- conditional knockout mice compared to controls. Remarkably, Prox1-/- conditional knockout mice had smaller lesions than controls. Altogether, these data show that Prox1 is required to inhibit OPC proliferation and for OL differentiation, and could be a relevant component of the regenerative glial response. Therapeutic uses of glia and stem cells to promote regeneration and repair after central nervous system injury would benefit from manipulating Prox1.     

Bone Morphogenetic Protein-2 Promotes Survival and Differentiation of Striatal GABAergic Neurons in the Absence of Glial Cell Proliferation

We examined the potential neurotrophic effects of bone morphogenetic protein (BMP)-2 on the survival and differentiation of neurons cultured from the rat developing striatum at embryonic day 16, a period during which the mRNAs for BMP-2 and its receptor subunits (types IA, IB, and II) were detected. BMP-2 exerted potent activity to promote the survival of striatal neurons and increased the number of surviving microtubule-associated protein-2-positive cells by 2.4-fold as compared with the control cultures after 4 days in vitro. Although basic fibroblast growth factor (bFGF) also showed relatively high activity to promote the survival of striatal neurons, transforming growth factor-beta1, -beta2, and -beta3, glial cell line-derived neurotrophic factor, or brain-derived neurotrophic factor promoted their survival weakly. Striatal neurons cultured in the presence of BMP-2 or bFGF possessed extensive neurite outgrowths, the majority of which were GABA-immunoreactive. Inhibition of glial cell proliferation by 5-fluorodeoxyuridine did not affect the capacity of BMP-2 to promote the survival of striatal GABAergic neurons. In contrast, the ability of bFGF to promote the survival of striatal neurons was inhibited significantly by the treatment of cells with 5-fluorodeoxyuridine. All these results suggest that BMP-2 exerts potent neurotrophic effects on the striatal GABAergic neurons in a glial cell-independent manner.