Expression of ezrin in glial tubes in the adult subventricular zone and rostral migratory stream

Ezrin is a member of the ERM (ezrin-radixin-moesin) family of membrane-cytoskeletal linking proteins. ERM proteins are involved in a wide variety of cellular functions including cell motility, signal transduction, cell-cell interaction and cell-matrix recognition. A recent in situ hybridization study showed that the mRNA encoding ezrin is expressed in neurogenic regions of the mature brain including the subventricular zone (SVZ) and rostral migratory stream (RMS); however, the specific cell types expressing ezrin and their relationship to migrating and proliferating cells in these regions have not been characterized previously. In this study, we used immunocytochemistry to perform double labeling with a variety of cell-type specific markers to characterize the expression of ezrin in the SVZ and RMS of adult mice. Ezrin was expressed at high levels in both the SVZ and RMS where ezrin-immunopositive processes formed a trabecular network surrounding the proliferating and migrating cells. Ezrin-positive cells co-labeled with the glial makers S100beta and GFAP (glial fibrillary acidic protein), but only minimally with the early neuronal markers beta III tubulin and polysialylated form of neural cell adhesion molecule 1 (PSA-NCAM), indicating that ezrin was expressed primarily in the glial tube cells. Ezrin positive cells also expressed beta-catenin, a membrane-complex protein previously implicated in the regulation of stem-cell proliferation and neuronal migration. Glial tube cells act as both precursors of, and a physical channel for, migrating neuroblasts. Bi-directional signals between glial tube cells and migrating neuroblasts have been shown to regulate the rates of both proliferation of the precursor cells and migration of the newly generated neuroblasts. Our finding that ezrin and beta-catenin are both present at the cell membrane of the glial tube cells suggests that these proteins may be involved in those signaling processes.     

Expression of amyloid precursor protein-like molecule in astroglial cells of the subventricular zone and rostral migratory stream of the adult rat forebrain

In adult mammals, new neurons in the subventricular zone (SVZ) of the lateral ventricle (LV) migrate tangentially through the rostral migratory stream (RMS) to the olfactory bulb (OB), where they mature into local interneurons. Using a monoclonal antibody for the beta-amyloid precursor protein (APP) (mAb 22C11), which is specific for the amino-terminal region of the secreted form of APP and recognizes all APP isoforms and APP-related proteins, immunoreactivity was detected in specific subpopulations of cells in the SVZ and RMS of the adult rat forebrain. In the SVZ, APP-like immunoreactivity was detected in the ependymal cells lining the LV and some of the subependymal cells. The latter were regarded as astrocytes, because they were positive for the glial markers, S-100 protein (S-100) and glial fibrillary acidic protein (GFAP). APP-like immunoreactive astrocytes exhibited strong labelling of the perinuclear cytoplasm and often possessed a long, fine process similar to that found with radial glia. The process extended to an APP-like immunoreactive meshwork in the RMS that consisted of cytoplasmic processes of astrocytes forming 'glial tubes'. Double-immunofluorescent labelling with a highly polysialylated neural cell adhesion molecule (PSA-NCAM) confirmed that the APP-like immunoreactive astrocytes in the SVZ and meshwork in the RMS made close contact with PSA-NCAM-immunopositive neuroblasts, suggesting an interaction between APP-containing cells and neuroblasts. This region of the adult brain is a useful in vivo model to investigate the role of APP in neurogenesis.     

肝细胞癌中Ezrin、Moesin表达的临床病理学意义

目的探讨肝细胞癌中Ezrin、Moesin的表达及其与肝细胞癌分化程度、恶性程度及侵袭的关系。方法根据Edmondson分级对肝细胞癌组织分级,采用免疫组化的方法检测了23例肝细胞癌组织、癌旁组织和正常肝组织中Ezrin、Moesin的表达。结果（1）Ezrin、Moesin在肝细胞癌组织、癌旁组织和正常肝组织中均有表达。（1）Ezrin在肝细胞癌组织中表达显著高于癌旁组织和正常肝组织（P〈0．001）,肝细胞癌组织中高侵袭组表达显著高于低侵袭组（P=0．023）,并与Edmondson分级（P=0．004）显著相关。（3）Moesin在肝细胞癌组织中的表达显著高于正常肝组织（P=0．003）,肝细胞癌组织中高侵袭组与低侵袭组的表达差异无显著性（P=0．448）,而与Edmondson分级（P=0．008）显著相关。结论Ezrin在肝细胞癌组织中表达增加与Edmondson分级和侵袭性相关;Moesin在肝细胞癌组织中表达增加与Edmondson分级相关,而与侵袭性无关。     

Immunohistochemical assessment of ezrin and moesin in colorectal carcinoma

Ezrin and moesin are important molecules of the ERM family of proteins, which regulate cell adhesion and migration. The aim of this study was to evaluate the intensity and pattern of ezrin and moesin expression in colorectal carcinoma (CRC) together with correlating their expression with the clinico-pathologic features of this neoplasm. This study was carried out on 48 CRC and 10 adenoma specimens. All adenoma and 95% of CRC cases showed both ezrin and moesin expression. Ezrin was predominantly cytoplasmic in adenoma cases in comparison to membranous localization in carcinoma cases. Moesin was predominantly expressed in stroma (inflammatory cells and fibroblasts) in carcinoma (89.1%) compared with adenoma (50%). High H-score of ezrin expression was associated with adenocarcinoma type (P = .024) and was inversely correlated with mitotic count (P = .005). High H-score of moesin expression was associated with early Dukes staging of CRC (P = .016), absence of lymph node involvement (P = .022), and low number of involved lymph nodes (P = .04). The association of ezrin with favorable prognostic parameters may be due to its prominent membranous localization. The stroma of CRC could stand against invasion by expression of moesin. Ezrin and moesin are independently expressed from each other.     

Cocaine regulates ezrin–radixin–moesin proteins and RhoA signaling in the nucleus accumbens

The ezrin–radixin–moesin (ERM) proteins are a family of widely distributed membrane-associated proteins and have been implicated not only in cell-shape determination but also in signaling pathway. The nucleus accumbens (NAcc) is an important neuronal substrate mediating the effects of drugs of abuse. However, it has not been determined yet how ERM proteins are regulated in this site by drugs of abuse. Here we show in rat that the phosphorylation levels of ERM protein are dose- and time-dependently decreased in the NAcc by a single injection of cocaine (15 or 30 mg/kg i.p.). Further, we show that the amount of active RhoA, a small GTPase protein, is significantly reduced in the NAcc by cocaine, while the phosphorylation levels of ERM protein are also decreased by bilateral microinjections in this site of the Rho kinase inhibitors. Together, these results suggest that cocaine reduces phosphorylated ERM levels in the NAcc by making downregulation of RhoA–Rho kinase signaling, which may importantly contribute to initiate synaptic changes in this site leading to drug addiction.     

Expression of angiogenic and neurotrophic factors in the progenitor cell niche of adult monkey subventricular zone

The subventricular zone along the anterior horn (SVZa) of the cerebral lateral ventricle of adult mammals contains multipotent progenitor cells, which supposedly exist in an angiogenic niche. Numerous signals are known to modulate the precursor cell proliferation, migration or differentiation, in rodent models. In contrast, the data on signals regulating the primate SVZa precursors in vivo are scarce. We analyzed the expression at protein level of a panel of angiogenic and/or neurotrophic factors and their receptors in SVZa of adult macaque monkeys, under normal condition or after transient global ischemia which enhances endogenous progenitor cell proliferation. We found that fms-like tyrosine kinase 1 (Flt1), a receptor for vascular endothelial cell growth factor, was expressed by over 30% of the proliferating progenitors, and the number of Flt1-positive precursors was significantly increased by the ischemic insult. Smaller fractions of mitotic progenitors were positive for the neurotrophin receptor tropomyosin-related kinase (Trk) B or the hematopoietic receptor Kit, while immature neurons expressed Flt1 and the neurotrophin receptor TrkA. Further, SVZa astroglia, ependymal cells and blood vessels were positive for distinctive sets of ligands/receptors, which we characterized. The presented data provide a molecular phenotypic analysis of cell types comprising adult monkey SVZa, and suggest that a complex network of angiogenic/neurotrophic signals operating in an autocrine or paracrine manner may regulate SVZa neurogenesis in the adult primate brain.     

Ionizing radiation induced long-term alterations in the adult rat rostral migratory stream

Ionizing radiation can induce significant injury to normal brain structures. To assess radiation-induced late effects, adult male Wistar rats received whole-body exposure with fractionated doses of gamma rays (a total dose of 4 Gy) and were investigated thirty, sixty and ninety days later. Immunohistochemistry and confocal microscopy were used to determine the density of neuroblasts derived from the anterior subventricular zone (SVZa) and brain resident microglia distributed along and/or adjacent to subventricular zone–olfactory bulb axis (SVZ–OB axis). Cell counting was performed in four anatomical parts along the well defined pathway, known as the rostral migratory stream (RMS) represented by the SVZa, vertical arm, elbow and horizontal arm of the RMS. Strong overdistribution of neuroblasts was seen in the SVZa thirty and sixty days after irradiation replaced by a steep decline in the following parts of the RMS and the highest decrease ninety days after radiation treatment along the entire SVZ–OB axis. Radiation treatment led to a decline or loss of microglia in almost all counted parts through the entire experiment. Results showed that ultimate decline of the SVZa descendants and loss of microglia suggests a contributory role of reduced neurogenesis in the development of radiation-induced late effects.     

Differential expression and distribution of ezrin,radixin and moesin in human natural killer cells

Cytoskeleton plays a crucial role in natural killer cell function. In this study the expression and subcellular distribution of ezrin, radixin and moesin, a family of proteins that connect actin filaments to many membrane structures, were evaluated in human NK cells. The results showed that NK cells expressed all these proteins, while NK cell-deprived peripheral blood leukocytes and purified T lymphocytes did not express radixin. Only ezrin changed its distribution following IL-2 activation and all three ezrin, moesin and radixin were polarized on uropods of adherent natural killer cells. Ezrin and radixin co-localized with the perforin granules at the intimate sites of contact between NK and the target cells, while moesin remains uniformly distributed on the membrane of NK cells. Ezrin, radixin and perforin co-localization was undetected in non-lytic conjugates and inhibited by treatment with actin depolymerizing agents. These results suggest that ezrin and radixin may exert a role in NK activity, particularly in the trafficking of perforin granules to the NK/target cells contact site. Moreover, our data suggest that radixin may represent an additional biological marker of human NK cells and that this protein may hold a specific role in NK cell function.     

The nuclear receptor tailless is required for neurogenesis in the adult subventricular zone

The tailless (Tlx) gene encodes an orphan nuclear receptor that is expressed by neural stem/progenitor cells in the adult brain of the subventricular zone (SVZ) and the dentate gyrus (DG). The function of Tlx in neural stem cells of the adult SVZ remains largely unknown. We show here that in the SVZ of the adult brain Tlx is exclusively expressed in astrocyte-like B cells. An inducible mutation of the Tlx gene in the adult brain leads to complete loss of SVZ neurogenesis. Furthermore, analysis indicates that Tlx is required for the transition from radial glial cells to astrocyte-like neural stem cells. These findings demonstrate the crucial role of Tlx in the generation and maintenance of NSCs in the adult SVZ in vivo.     

Age-dependent regional changes in the rostral migratory stream

Throughout life the subventricular zone (SVZ) is a source of new olfactory bulb (OB) interneurons. From the SVZ, neuroblasts migrate tangentially through the rostral migratory stream (RMS), a restricted route approximately 5 mm long in mice, reaching the OB within 10–14 days. Within the OB, neuroblasts migrate radially to the granule and glomerular layers where they differentiate into granule and periglomerular (PG) cells and integrate into existing synaptic circuits. SVZ neurogenesis decreases with age, and might be a factor in age-related olfactory deficits. However, the effect of aging on the RMS and on the differentiation of interneuron subpopulations remains poorly understood. Here, we examine RMS cytoarchitecture, neuroblast proliferation and clearance from the RMS, and PG cell subpopulations at 6, 12, 18, and 23 months of age. We find that aging affects the area occupied by newly generated cells within the RMS and regional proliferation, and the clearance of neuroblasts from the RMS and PG cell subpopulations and distribution remain stable.     

Neural-specific inactivation of ShcA functions results in anatomical disorganization of subventricular zone neural stem cell niche in the adult brain

Shc(s) family of adaptor molecules has been implicated in several physiological functions. In particular, our previous studies have shown major roles in the mechanisms that control the transition from proliferating neural stem cells (NSCs) to postmitotic neurons in the mammalian brain. In the adult brain, ShcA expression is mainly restricted to a subpopulation of cells in the subventricular zone (SVZ) neurogenic area, enlightening a potential role for this molecule in the establishment/maintenance of this adult NSC niche. In order to investigate this matter, here we took advantage of Cre/lox technology with the purpose of interfering with (or delete) ShcA function in nestin-expressing neural progenitors in vivo. Our analyses revealed signs of anatomical disorganization in the adult brain at the boundary between the striatum and the corpus callosum and reduced thickness both at the ventricular level and through the rostral migratory stream. Analysis of cell proliferation and cell death unveiled a prominent reduction of the former and no substantial alterations of the latter. Ultrastructural studies showed SVZ anatomical disarray and manifest variation in the SVZ cell type composition. In conclusion, these results provide evidence for a role of ShcA in the assembly and/or maintenance of the SVZ NSC niche in the adult brain.     

Multiphoton microscope imaging: The behavior of neural progenitor cells in the rostral migratory stream

Neural progenitor cells (NPCs) in the subventricular zone (SVZ) travel a long distance along the rostral migratory stream (RMS) to give rise to interneurons in the olfactory bulb (OB). Using the multiphoton microscope and time-lapse recording techniques we here report the behavior of NPCs in the RMS under both intact and ischemic conditions in living brain slices. The NPCs were visualized in 3-week-old transgenic mice that carry the reporter gene, green fluorescent protein (GFP), driven by the nestin promoter. Cortical brain ischemia was induced by permanent occlusion of the right common carotid artery and the middle cerebral artery. We observed that the RMS contained two populations of NPCs: nonmigrating cells (bridge cells) and migrating cells. Bridge cells enabled migrating cells to travel and also produced new cells in the RMS. The direction of NPC migration in the RMS was bidirectional in both intact and ischemic conditions. Cortical ischemia impeded NPC travel in the RMS next to the lesion area during the early period of ischemia. Cell–cell contact was a prominent feature affecting NPC translocation and migratory direction. These data suggest that behavior and function of nestin-positive NPCs in the RMS are variable. Cell–cell contacts and microenvironmental changes influence NPC behavior in the RMS. This study may provide insights to help in understanding NPC biology.     

The cellular composition and morphological organization of the rostral migratory stream in the adult human brain

The rostral migratory stream (RMS) is the major pathway by which progenitor cells migrate from the subventricular zone (SVZ) to the olfactory bulb (OB) in rodents, rabbits and primates. However, the existence of an RMS within the adult human brain has been elusive. Immunohistochemical studies utilising cell-type specific markers for early progenitor cells (CD133), proliferating cells (PCNA), astrocytes and type B cells (GFAP) and migrating neuroblasts (PSA-NCAM), reveal that the adult human RMS is organized into layers containing glial cells, proliferating cells and neuroblasts. In addition, the RMS is arranged around a remnant of the ventricular cavity that extends from the SVZ to the OB as seen by immunohistological staining analysis and electron microscopy, showing the presence of basal bodies and a typical 9 + 2 arrangement of tubulin in tufts of cilia from all levels of the RMS. Overall, these findings suggest that a pathway of migratory progenitor cells similar to that seen in other mammals is present within the adult human brain and that this pathway could provide for neurogenesis in the human forebrain. These findings contribute to the scientific understanding of adult neurogenesis and establish the detailed cytoarchitecture of this novel neurogenic niche in the human brain.     

Ezrin/radixin/moesin proteins and Rho GTPase signalling in leucocytes

The ezrin/radixin/moesin (ERM) family of actin-binding proteins act both as linkers between the actin cytoskeleton and plasma membrane proteins and as signal transducers in responses involving cytoskeletal remodelling. The Rho family of GTPases also regulate cytoskeletal organisation, and several molecular pathways linking ERM proteins and Rho GTPases have been described. This review discusses recent findings on ERM protein function in leucocytes and how these may be integrated with Rho GTPase signalling.     

Conditional ablation of Tbr2 results in abnormal development of the olfactory bulbs and subventricular zone‐rostral migratory stream

Development of the olfactory bulb (OB) is a complex process that requires contributions from several progenitor cell niches to generate neuronal diversity. Previous studies showed that Tbr2 is expressed during the generation of glutamatergic OB neurons in rodents. However, relatively little is known about the role of Tbr2 in the developing OB or in the subventricular zone‐rostral migratory stream (SVZ‐RMS) germinal niche that gives rise to many OB neurons. Results: Here, we use conditional gene ablation strategies to knockout Tbr2 during embryonic mouse olfactory bulb morphogenesis, as well as during perinatal and adult neurogenesis from the SVZ‐RMS niche, and describe the resulting phenotypes. We find that Tbr2 is important for the generation of mitral cells in the OB, and that the olfactory bulbs themselves are hypoplastic and disorganized in Tbr2 mutant mice. Furthermore, we show that the SVZ‐RMS niche is expanded and disordered following loss of Tbr2, which leads to ectopic accumulation of neuroblasts in the RMS. Lastly, we show that adult glutamatergic neurogenesis from the SVZ is impaired by loss of Tbr2. Conclusions: Tbr2 is essential for proper morphogenesis of the OB and SVZ‐RMS, and is important for the generation of multiple lineages of glutamatergic olfactory bulb neurons. Developmental Dynamics 243:440–450, 2014. © 2013 Wiley Periodicals, Inc.     

喙端迁移流的发生及其细胞凋亡

目的 研究生后不同日龄小鼠喙端迁移流（RMS）的发育,神经干细胞增殖和凋亡的规律。方法 利用Caspase-8免疫荧光标记法和5’-溴脱氧尿嘧啶核苷（BrdU）法,对小鼠RMS内的神经干细胞增殖和凋亡进行研究（n =92）。结果 生后早期小鼠脑内,尤其是室管下区（SVZ）和RMS,存在大量的增殖细胞。随着小鼠年龄的增加,脑内干细胞逐渐减少,到成年,大脑皮质几乎见不到增殖的神经干细胞,但在SVZ和RMS仍可以看到许多增殖的神经干细胞。在RMS,神经干细胞增殖的同时伴随着细胞凋亡,干细胞的增殖与凋亡存在着正相关关系。结论 RMS的神经干细胞增殖与凋亡有重要的生理意义,通过细胞凋亡,RMS可以调节神经干细胞向嗅球迁移的数量,也可以调节干细胞向颗粒细胞分化。     

Ischemic preconditioning enhances neurogenesis in the subventricular zone

Ischemic preconditioning (IPC) before subsequent prolonged ischemia is considered an emerging endogenous means of ischemic brain protection. We tested whether IPC induces endogenous neurogenesis in the subventricular zone (SVZ) and angiogenesis in the peri-ischemic area. Middle cerebral artery occlusion was administered to rats by filament insertion for 10 min (IPC) and/or 2 h (prolonged focal ischemia [PFI]). IPC alone increased 5'-bromo-2'-deoxyuridine (BrdU) (+) cells 2.5-fold in the SVZ compared with controls at 7 days. The numbers of BrdU/doublecortin (Dcx) or BrdU/neuronal nuclei (NeuN) double-labeled cells also increased, but extents of BrdU/glial fibrillary acidic protein (GFAP) double-labeling in the SVZ were not different. The IPC+PFI group showed about a 40% reduction in infarct volume. PFI increased BrdU (+) cells in the SVZ, and this was greatly enhanced by IPC treatment. The number of BrdU/Dcx double-labeled cells was strongly increased in ischemic brains administered IPC. Differentiation into mature neurons was also enhanced at 14 and 28 days. In addition, IPC significantly promoted angiogenesis in the ischemic penumbra as indicated by von Willebrand factor (vWF) staining. Our results indicate that IPC enhances neurogenesis in the SVZ even without subsequent PFI, and also enhances neurogenesis and angiogenesis after subsequent PFI. We conclude that IPC confers neuroprotection, and also promotes endogenous neurogenesis and angiogenesis.     

Expression of drebrin E in migrating neuroblasts in adult rat brain: coincidence between drebrin E disappearance from cell body and cessation of migration

Migrating neuroblasts in the adult brain form the rostral migratory stream (RMS) from the lateral ventricle to the olfactory bulb (OB) and then differentiate in the OB. In this study, we immunohistochemically analyzed drebrin expression in the RMS of the adult rat brain. Although drebrin is concentrated in dendritic spines of mature neurons, drebrin-immunopositive (DIP) cell bodies were observed in the RMS. The polysialated form of a neural cell adhesion molecule (PSA-NCAM) was detected in DIP cells. K(i)-67, a marker of proliferating cells, was also detected in a subset of DIP cells; however, neither glial fibrillary acidic protein, nestin nor vimentin was detected in DIP cells. These results indicate that DIP cells in the RMS are migrating neuroblasts. An image subtraction method, based on using anti-pan-drebrin and anti-drebrin A antibodies, demonstrated that DIP migrating neuroblasts are immunopositive for drebrin E but not for drebrin A (E+A-). Furthermore, olfactory bulbectomy increased the number of cells with drebrin E+A- signals in the RMS, indicating that these cells migrate along the RMS. Drebrin E+A- cells were also found in the subgranular layer of the dentate gyrus and in the piriform cortex. Thus, detection of drebrin E+A- signals is useful for identifying migrating neuroblasts in the adult brain. In the OB, drebrin E+A- signals were observed in the cell bodies of migrating neuroblasts in the core region; however, only fibrous and punctate drebrin E+A- signals were observed in postmigratory neuroblasts at the outer layers. These data demonstrate that the disappearance of drebrin E+A- signals from the cell body coincides with the cessation of neuronal migration. The disappearance of drebrin E from the cell body may be a molecular switch for the cessation of migration in newly generated neuroblasts.