Neuronal differentiation associated with Gli3 expression predicts favorable outcome for patients with medulloblastoma

Medulloblastoma (MB) is a malignant cerebellar tumor arising in children, and its ontogenesis is regulated by Sonic Hedgehog (Shh) signaling. No data are available regarding the correlation between expression of Gli3, a protein lying downstream of Shh, and neuronal differentiation of MB cells, or the prognostic significance of these features. We re‐evaluated the histopathological features of surgical specimens of MB taken from 32 patients, and defined 15 of them as MB with neuronal differentiation (ND), three as MB with both glial and neuronal differentiation (GD), and 14 as differentiation‐free (DF) MB. Gli3‐immunoreactivity (IR) was evident as a clear circular stain outlining the nuclei of the tumor cells. The difference in the frequency of IR between the ND+GD (94.4%) and DF (0%) groups was significant (P < 0.001). The tumor cells with ND showed IR for both Gli3 and neuronal nuclei. Ultrastructurally, Gli3‐IR was observed at the nuclear membrane. The overall survival and event‐free survival rates of the patients in the ND group were significantly higher than those in the other groups. The expression profile of Gli3 is of considerable significance, and the association of ND with this feature may be prognostically favorable in patients with MB.     

Multifaceted Functions of Rab23 on Primary Cilium-Mediated and Hedgehog Signaling-Mediated Cerebellar Granule Cell Proliferation

Sonic hedgehog (Shh) signaling from the primary cilium drives cerebellar granule cell precursor (GCP) proliferation. Mutations of hedgehog (Hh) pathway repressors commonly cause medulloblastoma, the most prevalent and malignant childhood brain tumor that arises from aberrant GCP proliferation. We demonstrate that Nestin Cre-driven conditional knock-out (CKO) of a Shh pathway repressor-Rab23 in the mouse brain of both genders caused mis-patterning of cerebellar folia and elevated GCP proliferation during early development, but with no prevalent occurrence of medulloblastoma at adult stage. Strikingly, Rab23-depleted GCPs exhibited upregulated basal level of Shh pathway activities despite showing an abnormal ciliogenesis of primary cilia. In line with the compromised ciliation, Rab23-depleted GCPs were desensitized against Hh pathway activity stimulations by Shh ligand and Smoothened (Smo) agonist-SAG, and exhibited attenuated stimulation of Smo-localization on the primary cilium in response to SAG. These results implicate multidimensional actions of Rab23 on Hh signaling cascade. Rab23 represses the basal level of Shh signaling, while facilitating primary cilium-dependent extrinsic Shh signaling activation. Collectively, our findings unravel instrumental roles of Rab23 in GCP proliferation and ciliogenesis. Furthermore, Rab23''s potentiation of Shh signaling pathway through the primary cilium and Smo suggests a potential new therapeutic strategy for Smo/primary cilium-driven medulloblastoma.SIGNIFICANCE STATEMENT Primary cilium and Sonic hedgehog (Shh) signaling are known to regulate granule cell precursor (GCP) proliferation. Aberrant overactivation of Shh signaling pathway ectopically increases GCP proliferation and causes malignant childhood tumor called medulloblastoma. However, the genetic and molecular regulatory cascade of GCP tumorigenesis remains incompletely understood. Our finding uncovers Rab23 as a novel regulator of hedgehog (Hh) signaling pathway activity and cell proliferation in GCP. Intriguingly, we demonstrated that Rab23 confers dual functions in regulating Shh signaling; it potentiates primary cilium and Shh/Smoothened (Smo)-dependent signaling activation, while antagonizes basal level Hh activity. Our data present a previously underappreciated aspect of Rab23 in mediating extrinsic Shh signaling upstream of Smo. This study sheds new light on the mechanistic insights underpinning Shh signaling-mediated GCP proliferation and tumorigenesis.     

Subcellular Distribution of Patched and Smoothened in the Cerebellar Neurons

The Sonic hedgehog (Shh) signaling pathway carries out a wide range of biological functions such as patterning of the embryonic neural tube and expansion of cerebellar granule cell precursors. We previously have found that the Shh signaling receptors, Patched1 (Ptch1) and Smoothened (Smo), are expressed in hippocampal neurons of developing and adult rats, suggesting the continued presence of Shh signaling in postmitotic, differentiated neurons. Here, we report that Ptch1 and Smo are present in the processes and growth cones of immature neurons in the developing cerebellum, and that, in the mature cerebellum, Ptch1 and Smo are expressed by several types of neurons including Purkinje cells, granule cells, and interneurons. Within these neurons, Ptch1 and Smo are predominantly localized in the postsynaptic side of the synapses, a distribution pattern similar to that found in hippocampal neurons. Our findings provide morphological evidence that Shh signaling events are not confined to neuronal precursors and are likely to have ongoing roles within the postmitotic neurons of the developing and adult cerebellum.     

Caveolin-1 regulates neural differentiation of rat bone mesenchymal stem cells into neurons by modulating Notch signaling

Bone marrow mesenchymal stem cells (MSCs) are known to differentiate into neurons in vitro. However, the mechanism underlying MSC differentiation remains controversial. A recent analysis has shown that Notch signaling is involved in regulating the differentiation of MSCs. This study examines the potential mechanism of the differentiation of MSCs into neurons, and it considers the role of caveolin-1 in this process. We investigated neuron differentiation and Notch signaling by detecting the expression levels of microtubule-associated protein 2 (MAP-2), Neuron-specific Enolase (NSE), Notch-1, Notch intracellular domain (NICD) and hairy enhancer of split 5 (Hes5). We found that by down-regulating caveolin-1 during induction, MSCs were prone to neural differentiation and expressed high levels of neuronal markers. Meanwhile, the expression levels of Notch-1, NICD and Hes5 decreased. Our results indicate that down-regulation of caveolin-1 promotes the neuronal differentiation of MSCs by modulating the Notch signaling pathway.     

Purmorphamine对BV2细胞帕金森病相关基因Nurr1表达的影响

目的探讨Purmorphamine(PM)激活小胶质细胞瘤BV2细胞中Sonic hedgehog(SHH)信号通路对帕金森病(PD)相关基因Nurr1表达的影响。方法体外培养BV2小胶质细胞并分为对照组、脂多糖(LPS)处理组、PM+LPS处理组以及PM处理组,运用荧光定量PCR(Q-PCR)检测经LPS处理后BV2细胞中SHH信号通路Smoothened(Smo)、Gli1及Nurr1基因mRNA表达情况;PM激活SHH信号通路后,Q-PCR检测Nurr1mRNA含量以及炎性反应因子白细胞介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)的mRNA表达情况。结果(1)与对照组相比,LPS处理后4h和24h时Smo和Gli1mRNA表达均升高(P0.01,P0.05);(2)与对照组相比,PM处理组细胞Smo和Gli1mRNA表达升高(P0.01),LPS组Nurr1、IL-1β、TNF-αmRNA表达亦均升高(均P0.01);而PM+LPS组Nurr1、IL-1β、TNF-αmRNA表达均较LPS处理组下降(均P0.01)。结论PM激活SHH信号通路能够抑制BV2细胞中Nurr1的表达,并能发挥抑制炎性反应作用。     

Multipotent mesenchymal stromal cells increase tPA expression and concomitantly decrease PAI-1 expression in astrocytes through the sonic hedgehog signaling pathway after stroke (in vitro study)

Multipotent mesenchymal stromal cells (MSCs) increase tissue plasminogen activator (tPA) activity in astrocytes of the ischemic boundary zone, leading to increased neurite outgrowth in the brain. To probe the mechanisms that underlie MSC-mediated activation of tPA, we investigated the morphogenetic gene, sonic hedgehog (Shh) pathway. In vitro oxygen and glucose deprivation and coculture of astrocytes and MSCs were used to mimic an in vivo ischemic condition. Both real-time-PCR and western blot showed that MSC coculture significantly increased the Shh level and concomitantly increased tPA and decreased plasminogen activator inhibitor 1 (PAI-1) levels in astrocytes. Inhibiting the Shh signaling pathway with cyclopamine blocked the increase of tPA and the decrease of PAI-1 expression in astrocytes subjected to MSC coculture or recombinant mouse Shh (rm-Shh) treatment. Both MSCs and rm-Shh decreased the transforming growth factor-β1 level in astrocytes, and the Shh pathway inhibitor cyclopamine reversed these decreases. Both Shh-small-interfering RNA (siRNA) and Glil-siRNA downregulated Shh and Gli1 (a key mediator of the Shh transduction pathway) expression in cultured astrocytes and concomitantly decreased tPA expression and increased PAI-1 expression in these astrocytes after MSC or rm-Shh treatment. Our data indicate that MSCs increase astrocytic Shh, which subsequently increases tPA expression and decreases PAI-1 expression after ischemia.     

肉苁蓉多糖通过Shh通路缓解EAE小鼠的临床症状

目的探讨音猬因子(Sonic hedgehog,Shh)通路在实验性自身免疫性脑脊髓炎(experimental autoimmune encephalomyelitis,EAE)小鼠发病过程中的作用,及肉苁蓉多糖(cistanche deserticola polysaccharide,CDPS)能否通过该通路缓解EAE小鼠临床症状。方法给予C57BL/6小鼠皮下注射髓鞘少突细胞糖蛋白35-55多肽(myelin oligodendrocyte glycoprotein 35-55,MOG35-55)抗原制备EAE动物模型。将60只小鼠随机分为正常对照组、EAE模型组、CDPS治疗组以及CDPS+Smo受体阻断剂环王巴明(cyc)治疗组(以下简称CDPS+cyc治疗组)4组,每组各15只。观察各组小鼠免疫注射后0~26d的临床症状评分,采用勒克斯光蓝染色(Luxol Fast Blue,LFB)检测各组小鼠脊髓组织内髓鞘脱失情况,Western blot法检测脊髓组织内Shh、碎片蛋白-1(Patched-1,Ptc-1)蛋白表达,采用RT-PCR检测脊髓组织内平滑蛋白(Smoothened,Smo)mRNA、神经胶质瘤相关癌基因1(Glioma-associated oncogene-1,Gli1)mRNA表达。结果自CDPS治疗第9天开始,CDPS治疗组小鼠临床症状评分低于EAE模型组(P<0.05),而CDPS+cyc治疗组临床症状评分高于CDPS组(P <0.05)。CDPS治疗组小鼠脊髓LFB评分较EAE模型组降低(t=9.64,P<0.01),而CDPS+cyc治疗组其LFB评分与EAE模型组比较差异无统计学意义(P>0.05)。EAE模型组小鼠脊髓组织内Shh、Ptc-1蛋白以及Smo mRNA、Gli1mRNA表达水平较正常组升高(均P<0.01),经CDPS治疗后,上述因子表达进一步升高(均P<0.01),而经cyc干预后,上述因子表达较CDPS治疗组降低(均P<0.01)。结论 CDPS对EAE小鼠临床症状有改善作用,其作用途径可能与Shh信号通路有关。     

bFGF和N2体外联合定向诱导骨髓间质干细胞向神经元样细胞分化

目的:将成年大鼠骨髓间质干细胞(mesenchymal stem cells，MSCs)体外定向诱导分化为神经元样细胞。方法:成年大鼠骨髓间质干细胞，进行体外扩增、纯化培养，对纯化后的MSCs，使用碱性成纤维生长因子(basic fibroblast growth factor，bFGF)和神经培养添加剂N2进行诱导，使MSCs分化为神经元样细胞，并进行免疫细胞化学方法鉴定。结果：95．6％的MSCs出现形态改变，呈神经元样。免疫细胞化学法鉴定，显示神经元特异性烯醇化酶(NSE)、神经丝蛋白(NF)和神经干细胞标志物巢蛋白(nestin)阳性表达。结论体外MSCs可以分化为神经元样细胞。     

Conditioned medium from human amniotic epithelial cells may induce the differentiation of human umbilical cord blood mesenchymal stem cells into dopaminergic neuron‐like cells

Dopaminergic (DA) neuron therapy has been established as a new clinical tool for treating Parkinson's disease (PD). Prior to cell transplantation, there are two primary issues that must be resolved: one is the appropriate seed cell origin, and the other is the efficient inducing technique. In the present study, human umbilical cord blood‐derived mesenchymal stem cells (hUCB‐MSCs) were used as the available seed cells, and conditioned medium from human amniotic epithelial cells (ACM) was used as the inducing reagent. Results showed that the proportion of DA neuron‐like cells from hUCB‐MSCs was significantly increased after cultured in ACM, suggested by the upregulation of DAT, TH, Nurr1, and Pitx3. To identify the process by which ACM induces DA neuron differentiation, we pretreated hUCB‐MSCs with k252a, the Trk receptor inhibitor of brain‐derived neurotrophic factor (BDNF) and nerve growth factor (NGF), and found that the proportion of DA neuron‐like cells was significantly decreased compared with ACM‐treated hUCB‐MSCs, suggesting that NGF and BDNF in ACM were involved in the differentiation process. However, we could not rule out the involvement of other unidentified factors in the ACM, because ACM + k252a treatment does not fully block DA neuron‐like cell differentiation compared with control. The transplantation of ACM‐induced hUCB‐MSCs could ameliorate behavioral deficits in PD rats, which may be associated with the survival of engrafted DA neuron‐like cells. In conclusion, we propose that hUCB‐MSCs are a good source of DA neuron‐like cells and that ACM is a potential inducer to obtain DA neuron‐like cells from hUCB‐MSCs in vitro for an ethical and legal cell therapy for PD. © 2013 Wiley Periodicals, Inc.     

Light‐controlled astrocytes promote human mesenchymal stem cells toward neuronal differentiation and improve the neurological deficit in stroke rats

Astrocytes are key components of the central nervous system (CNS) and release factors to support neural stem cell proliferation, differentiation, and migration. Adenosine 5'‐triphosphate (ATP) is one of the key factors released upon activation of astrocytes that regulates the neural stem cell's function. However, it is not clear whether ATP derived from the depolarized astrocytes plays a vital role in promoting the neuronal differentiation of mesenchymal stem cells (MSCs) in vitro and in vivo. Herein, for the first time, we co‐cultured MSCs with light‐stimulated‐channelrhodopsin‐2 (ChR2)‐astrocytes, and observed that the neuronal differentiation of MSCs was enhanced by expressing more neuronal markers, Tuj1 and NeuN. The ChR2‐astrocyte‐conditioned medium also stimulated MSCs differentiating into neuronal lineage cells by expressing more Tuj1 and Pax6, which was blocked by the P2X receptor antagonist, TNP‐ATP. Then we found that light‐depolarization of astrocytes significantly increased ATP accumulation in their bathing medium without impairing the cell membrane. We further found that ATP up‐regulated the Tuj1, Pax6, FZD8 and β‐catenin mRNA levels of MSCs, which could be reversed by application of TNP‐ATP. Together these in vitro data provided convergent evidence that ATP from light‐depolarized‐astrocytes activated the wnt/β‐catenin signaling of MSCs through binding to the P2X receptors, and promoted the neuronal differentiation of MSCs. Finally but importantly, our study also demonstrated in stroke rats that light‐controlled astrocytes stimulated endogenous ATP release into the ischemic area to influence the transplanted MSCs, resulting in promoting the MSCs towards neuronal differentiation and improvements of neurological deficit. GLIA 2013;62:106–121     

音速波状蛋白促进骨髓间充质干细胞向多巴胺能神经元分化

目的探讨音速波状蛋白（Shh）促进人骨髓间充质干细胞（MSCs）体外定向分化为多巴胺能神经元样细胞的作用。方法体外分离、扩增和鉴定人骨髓MSCs。采用不同诱导方案诱导MSCs向神经元和多巴胺能神经元样细胞定向转化后,进行抗神经巢蛋白（Nestin）、神经元特异烯醇化酶（NSE）、神经胶质纤维酸性蛋白（GFAP）、酪氨酸羟化酶（TH）和多巴胺转运体（DAT）等免疫细胞化学染色,并计算阳性细胞百分率。结果实验组诱导后MSCs能分化为具有典型神经元形态的细胞,可见NSE、Nestin、GFAP、TH和DAT等神经细胞标志表达;对照组MSCs细胞形态无明显变化,上述特异性标志物表达均为阴性。实验2组（诱导方案含Shh）与1组（诱导方案不含Shh）的NSE、Nestin、GFAP阳性细胞百分率的差异无统计学意义,但实验2组TH和DAT阳性细胞百分率明显高于实验1组,差异具有统计学意义（P〈0.05）。结论Shh可促进MSCs分化为多巴胺能神经元样细胞。