251
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Ivanov VN, Hei TK. Induction of apoptotic death and retardation of neuronal differentiation of human neural stem cells by sodium arsenite treatment. Exp Cell Res 2013; 319:875-87. [PMID: 23219847 PMCID: PMC3593966 DOI: 10.1016/j.yexcr.2012.11.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 11/26/2012] [Accepted: 11/27/2012] [Indexed: 12/21/2022]
Abstract
Chronic arsenic toxicity is a global health problem that affects more than 100 million people worldwide. Long-term health effects of inorganic sodium arsenite in drinking water may result in skin, lung and liver cancers and in severe neurological abnormalities. We investigated in the present study whether sodium arsenite affects signaling pathways that control cell survival, proliferation and neuronal differentiation of human neural stem cells (NSC). We demonstrated that the critical signaling pathway, which was suppressed by sodium arsenite in NSC, was the protective PI3K-AKT pathway. Sodium arsenite (2-4μM) also caused down-regulation of Nanog, one of the key transcription factors that control pluripotency and self-renewal of stem cells. Mitochondrial damage and cytochrome-c release induced by sodium arsenite exposure was followed by initiation of the mitochondrial apoptotic pathway in NSC. Beside caspase-9 and caspase-3 inhibitors, suppression of JNK activity decreased levels of arsenite-induced apoptosis in NSC. Neuronal differentiation of NSC was substantially inhibited by sodium arsenite exposure. Overactivation of JNK1 and ERK1/2 and down-regulation of PI3K-AKT activity induced by sodium arsenite were critical factors that strongly affected neuronal differentiation. In conclusion, sodium arsenite exposure of human NSC induces the mitochondrial apoptotic pathway, which is substantially accelerated due to the simultaneous suppression of PI3K-AKT. Sodium arsenite also negatively affects neuronal differentiation of NSC through overactivation of MEK-ERK and suppression of PI3K-AKT.
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Affiliation(s)
- Vladimir N Ivanov
- Center for Radiological Research, Department of Radiation Oncology, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, NY 10032, USA.
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252
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Liu XS, Chopp M, Wang XL, Zhang L, Hozeska-Solgot A, Tang T, Kassis H, Zhang RL, Chen C, Xu J, Zhang ZG. MicroRNA-17-92 cluster mediates the proliferation and survival of neural progenitor cells after stroke. J Biol Chem 2013; 288:12478-88. [PMID: 23511639 DOI: 10.1074/jbc.m112.449025] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The role of microRNAs (miRNAs) in mediating adult neurogenesis after stroke has not been extensively studied. The present study investigated the function of the miR17-92 cluster in adult neural progenitor cells after experimental stroke. We found that stroke substantially up-regulated miR17-92 cluster expression in neural progenitor cells of the adult mouse. Overexpression of the miR17-92 cluster either in cultured ischemic neural progenitor cells or in the subventricular zone (SVZ) of ischemic animals significantly increased cell proliferation, whereas inhibition of individual members of the miR17-92 cluster, miR-18a and miR-19a, suppressed cell proliferation and increased cell death. The miR17-92 cluster mediated PTEN (phosphatase and tensin homolog) expression, which is a predicted target of the miR17-92 cluster. Addition of Sonic hedgehog (Shh) protein up-regulated miR17-92 expression and elevated c-Myc protein in ischemic neural progenitor cells, whereas blockade of the Shh signaling pathway down-regulated miR17-92 cluster expression and reduced c-Myc levels. Overexpression of c-Myc up-regulated miR17-92 cluster expression. Intraventricular infusion of Shh and a Shh receptor inhibitor, cyclopamine, to ischemic animals further elevated and suppressed, respectively, miR17-92 cluster expression in the SVZ. These data indicate that the miR17-92 cluster plays an important role in mediating neural progenitor cell function and that the Shh signaling pathway is involved in up-regulating miR17-92 cluster expression.
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Affiliation(s)
- Xian Shuang Liu
- Department of Neurology, Henry Ford Health System, Detroit, Michigan 48202, USA.
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253
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Becker L, Peterson J, Kulkarni S, Pasricha PJ. Ex vivo neurogenesis within enteric ganglia occurs in a PTEN dependent manner. PLoS One 2013; 8:e59452. [PMID: 23527198 PMCID: PMC3602370 DOI: 10.1371/journal.pone.0059452] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 02/14/2013] [Indexed: 12/13/2022] Open
Abstract
A population of multipotent stem cells capable of differentiating into neurons and glia has been isolated from adult intestine in humans and rodents. While these cells may provide a pool of stem cells for neurogenesis in the enteric nervous system (ENS), such a function has been difficult to demonstrate in vivo. An extensive study by Joseph et al. involving 108 rats and 51 mice submitted to various insults demonstrated neuronal uptake of thymidine analog BrdU in only 1 rat. Here we introduce a novel approach to study neurogenesis in the ENS using an ex vivo organotypic tissue culturing system. Culturing longitudinal muscle and myenteric plexus tissue, we show that the enteric nervous system has tremendous replicative capacity with the majority of neural crest cells demonstrating EdU uptake by 48 hours. EdU+ cells express both neuronal and glial markers. Proliferation appears dependent on the PTEN/PI3K/Akt pathway with decreased PTEN mRNA expression and increased PTEN phosphorylation (inactivation) corresponding to increased Akt activity and proliferation. Inhibition of PTEN with bpV(phen) augments proliferation while LY294002, a PI3K inhibitor, blocks it. These data suggest that the ENS is capable of neurogenesis in a PTEN dependent manner.
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Affiliation(s)
- Laren Becker
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University, Stanford, California, United States of America
| | - Johann Peterson
- Department of Pediatrics, University of California Davis, Sacramento, California, United States of America
| | - Subhash Kulkarni
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Pankaj Jay Pasricha
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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254
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Luo X, Salgueiro Y, Beckerman SR, Lemmon VP, Tsoulfas P, Park KK. Three-dimensional evaluation of retinal ganglion cell axon regeneration and pathfinding in whole mouse tissue after injury. Exp Neurol 2013; 247:653-62. [PMID: 23510761 DOI: 10.1016/j.expneurol.2013.03.001] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 02/25/2013] [Accepted: 03/01/2013] [Indexed: 11/24/2022]
Abstract
Injured retinal ganglion cell (RGC) axons do not regenerate spontaneously, causing loss of vision in glaucoma and after trauma. Recent studies have identified several strategies that induce long distance regeneration in the optic nerve. Thus, a pressing question now is whether regenerating RGC axons can find their appropriate targets. Traditional methods of assessing RGC axon regeneration use histological sectioning. However, tissue sections provide fragmentary information about axonal trajectory and termination. To unequivocally evaluate regenerating RGC axons, here we apply tissue clearance and light sheet fluorescence microscopy (LSFM) to image whole optic nerve and brain without physical sectioning. In mice with PTEN/SOCS3 deletion, a condition known to promote robust regeneration, axon growth followed tortuous paths through the optic nerve, with many axons reversing course and extending towards the eye. Such aberrant growth was prevalent in the proximal region of the optic nerve where strong astroglial activation is present. In the optic chiasms of PTEN/SOCS3 deletion mice and PTEN deletion/Zymosan/cAMP mice, many axons project to the opposite optic nerve or to the ipsilateral optic tract. Following bilateral optic nerve crush, similar divergent trajectory is seen at the optic chiasm compared to unilateral crush. Centrally, axonal projection is limited predominantly to the hypothalamus. Together, we demonstrate the applicability of LSFM for comprehensive assessment of optic nerve regeneration, providing in-depth analysis of the axonal trajectory and pathfinding. Our study indicates significant axon misguidance in the optic nerve and brain, and underscores the need for investigation of axon guidance mechanisms during optic nerve regeneration in adults.
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Affiliation(s)
- Xueting Luo
- Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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255
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Kim W, Kim JH, Kong SY, Park MH, Sohn UD, Kim HJ. Comparison of ectopic gene expression methods in rat neural stem cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2013; 17:23-30. [PMID: 23439859 PMCID: PMC3579101 DOI: 10.4196/kjpp.2013.17.1.23] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 11/19/2012] [Accepted: 11/29/2012] [Indexed: 12/21/2022]
Abstract
Neural stem cells (NSCs) have the ability to proliferate and differentiate into various types of cells that compose the nervous system. To study functions of genes in stem cell biology, genes or siRNAs need to be transfected. However, it is difficult to transfect ectopic genes into NSCs. Thus to identify the suitable method to achieve high transfection efficiency, we compared lipid transfection, electroporation, nucleofection and retroviral transduction. Among the methods that we tested, we found that nucleofection and retroviral transduction showed significantly increased transfection efficiency. In addition, with retroviral transduction of Ngn2 that is known to induce neurogenesis in various types of cells, we observed facilitated final cell division in rat NSCs. These data suggest that nucleofection and retroviral transduction provide high efficiency of gene delivery system to study functions of genes in rat NSCs.
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Affiliation(s)
- Woosuk Kim
- Laboratory of Stem Cell and Molecular Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea
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256
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Kim HJ, Woo HM, Ryu J, Bok J, Kim JW, Choi SB, Park MH, Park HY, Koo SK. Conditional deletion of pten leads to defects in nerve innervation and neuronal survival in inner ear development. PLoS One 2013; 8:e55609. [PMID: 23393595 PMCID: PMC3564925 DOI: 10.1371/journal.pone.0055609] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 01/02/2013] [Indexed: 12/25/2022] Open
Abstract
All cellular phenomena and developmental events, including inner ear development, are modulated through harmonized signaling networks. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor, is a major signaling component involved in cross talk with key regulators of development; i.e., Wnt, Notch, and bone morphogenetic proteins. Although Pten function has been studied in various systems, its role in inner ear development is poorly understood. Here, we used inner ear-specific Pten conditional knockout mice and examined the characteristics of the inner ear. In a detailed analysis of the phenotype, reduced cochlear turning and widened epithelia were observed. Phalloidin staining of sensory epithelium revealed that hair cell patterns were disturbed; i.e., additional rows of hair cells were discovered. The neural abnormality revealed a reduction in and disorganization of nerve fibers, including apoptosis at the neural precursor stage. Pten deficiency induced increased phosphorylation of Akt at Ser473. The elevation of inhibitory glycogen synthase kinase 3β Ser9 phosphorylation (pGSK3β) was sustained until the neuronal differentiation stage at embryonic day 14.5, instead of pGSK3β downregulation. This is the first report on the influence of Pten/Akt/GSK3β signaling on the development of spiral ganglia. These results suggest that Pten is required for the maintenance of neuroblast number, neural precursors, and differentiation in the inner ear.
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Affiliation(s)
- Hyung Jin Kim
- Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, South Korea
| | - Hae-Mi Woo
- Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, South Korea
| | - Jihee Ryu
- Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, South Korea
| | - Jinwoong Bok
- Department of Anatomy, BK21 Project for Medical Science, Yonsei University College of Medicine, Seoul, South Korea
| | - Jin Woo Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, South Korea
| | - Sang Back Choi
- Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, South Korea
| | - Mi-Hyun Park
- Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, South Korea
| | - Hyun-Young Park
- Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, South Korea
| | - Soo Kyung Koo
- Center for Biomedical Sciences, National Institute of Health, Osong Health Technology Administration Complex 643, Yeonje-ri, Osong-eup, Cheongwon-gun, Chungcheongbuk-do, South Korea
- * E-mail:
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257
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Impaired autophagy in neurons after disinhibition of mammalian target of rapamycin and its contribution to epileptogenesis. J Neurosci 2013; 32:15704-14. [PMID: 23136410 DOI: 10.1523/jneurosci.2392-12.2012] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Certain mutations within the mammalian target of rapamycin (mTOR) pathway, most notably those affecting the tuberous sclerosis complex (TSC), lead to aberrant activation of mTOR and result in a high incidence of epilepsy in humans and animal models. Although hyperactivation of mTOR has been strongly linked to the development of epilepsy and, conversely, inhibition of mTOR by rapamycin treatment is protective against seizures in several models, the downstream epileptic mechanisms have remained elusive. Autophagy, a catabolic process that plays a vital role in cellular homeostasis by mediating the turnover of cytoplasmic constituents, is negatively regulated by mTOR. Here we demonstrate that autophagy is suppressed in brain tissues of forebrain-specific conditional TSC1 and phosphatase and tensin homlog knock-out mice, both of which display aberrant mTOR activation and seizures. In addition, we also discovered that autophagy is suppressed in the brains of human TSC patients. Moreover, conditional deletion of Atg7, an essential regulator of autophagy, in mouse forebrain neurons is sufficient to promote development of spontaneous seizures. Thus, our study suggests that impaired autophagy contributes to epileptogenesis, which may be of interest as a potential therapeutic target for epilepsy treatment and/or prevention.
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258
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Lu TL, Huang YF, You LR, Chao NC, Su FY, Chang JL, Chen CM. Conditionally ablated Pten in prostate basal cells promotes basal-to-luminal differentiation and causes invasive prostate cancer in mice. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 182:975-91. [PMID: 23313138 DOI: 10.1016/j.ajpath.2012.11.025] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 10/27/2012] [Accepted: 11/07/2012] [Indexed: 12/22/2022]
Abstract
Prostate glands comprise two major epithelial cell types: luminal and basal. Luminal cells have long been considered the cellular origin of prostate cancer (CaP). However, recent evidence from a prostate regeneration assay suggests that prostate basal cells can also give rise to CaP. Here, we characterize Pten-deficient prostate lesions arising from keratin 5-expressing basal cells in a temporally controlled system in mice. Pten-deficient prostate lesions arising from basal cells exhibited luminal phenotypes with higher invasiveness, and the cell fate of Pten-deficient basal cells was traced to neoplastic luminal cells. After temporally ablating Pten in keratin 8-expressing luminal cells, luminal-derived Pten-deficient prostate tumors exhibited slower disease progression, compared with basal-derived tumors, within 13 weeks after Pten ablation. Cellular proliferation was significantly increased in basal-derived versus luminal-derived Pten-deficient prostate lesions. Increased tumor invasion into the smooth muscle layer and aberrantly regulated aggressive signatures (Smad4 and Spp1) were identified exclusively in basal-derived Pten-deficient lesions. Interestingly, p63-expressing cells, which represent basal stem and progenitor cells of basal-derived Pten-deficient prostate lesions, were significantly increased, relative to cells of the luminal-derived prostate lesion. Furthermore, castration did not suppress cellular proliferation of either basal-derived or luminal-derived Pten-deficient prostate tumors. Taken together, our data suggest that, although prostate malignancy can originate from both basal and luminal populations, these two populations differ in aggressive potential.
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Affiliation(s)
- Tsai-Ling Lu
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
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259
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Abstract
Glioma is a heterogeneous disease process with differential histology and treatment response. It was previously thought that the histological features of glial tumors indicated their cell of origin. However, the discovery of continuous neuro-gliogenesis in the normal adult brain and the identification of brain tumor stem cells within glioma have led to the hypothesis that these brain tumors originate from multipotent neural stem or progenitor cells, which primarily divide asymmetrically during the postnatal period. Asymmetric cell division allows these cell types to concurrently self-renew whilst also producing cells for the differentiation pathway. It has recently been shown that increased symmetrical cell division, favoring the self-renewal pathway, leads to oligodendroglioma formation from oligodendrocyte progenitor cells. In contrast, there is some evidence that asymmetric cell division maintenance in tumor stem-like cells within astrocytoma may lead to acquisition of treatment resistance. Therefore cell division mode in normal brain stem and progenitor cells may play a role in setting tumorigenic potential and the type of tumor formed. Moreover, heterogeneous tumor cell populations and their respective cell division mode may confer differential sensitivity to therapy. This review aims to shed light on the controllers of cell division mode which may be therapeutically targeted to prevent glioma formation and improve treatment response.
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260
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Ji B, Chen Q, Liu B, Wu L, Tian D, Guo Z, Yi W. Glioma stem cell-targeted dendritic cells as a tumor vaccine against malignant glioma. Yonsei Med J 2013; 54:92-100. [PMID: 23225804 PMCID: PMC3521251 DOI: 10.3349/ymj.2013.54.1.92] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
PURPOSE Cancer stem cells have recently been thought to be closely related to tumor development and reoccurrence. It may be a promising way to cure malignant glioma by using glioma stem cell-targeted dendritic cells as a tumor vaccine. In this study, we explored whether pulsing dendritic cells with antigens of glioma stem cells was a potent way to induce specific cytotoxic T lymphocytes and anti-tumor immunity. MATERIALS AND METHODS Cancer stem cells were cultured from glioma cell line U251. Lysate of glioma stem cells was obtained by the repeated freezing and thawing method. Dendritic cells (DCs) were induced and cultured from the murine bone marrow cells, the biological characteristics were detected by electron microscope and flow cytometry. The DC vaccine was obtained by mixing DCs with lysate of glioma stem cells. The DC vaccine was charactirizated through the mixed lymphocyte responses and cell killing experiment in vitro. Level of interferon-γ (IFN-γ) in the supernatant was checked by ELISA. RESULTS After stimulation of lysate of glioma stem cell, expression of surface molecules of DC was up-regulated, including CD80, CD86, CD11C and MHC-II. DCs pulsed with lysate of glioma stem cells were more effective than the control group in stimulating original glioma cells-specific cytotoxic T lymphocytes responses, killing glioma cells and boosting the secretion of IFN-γ in vitro. CONCLUSION The results demonstrated DCs loaded with antigens derived from glioma stem cells can effectively stimulate naive T cells to form specific cytotoxic T cells, kill glioma cells cultured in vitro.
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Affiliation(s)
- Baowei Ji
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Qianxue Chen
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Baohui Liu
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Liquan Wu
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Daofeng Tian
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Zhentao Guo
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Wei Yi
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
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261
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Chen CC, Stairs DB, Boxer RB, Belka GK, Horseman ND, Alvarez JV, Chodosh LA. Autocrine prolactin induced by the Pten-Akt pathway is required for lactation initiation and provides a direct link between the Akt and Stat5 pathways. Genes Dev 2012; 26:2154-68. [PMID: 23028142 DOI: 10.1101/gad.197343.112] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Extrapituitary prolactin (Prl) is produced in humans and rodents; however, little is known about its in vivo regulation or physiological function. We now report that autocrine prolactin is required for terminal mammary epithelial differentiation during pregnancy and that its production is regulated by the Pten-PI3K-Akt pathway. Conditional activation of the PI3K-Akt pathway in the mammary glands of virgin mice by either Akt1 expression or Pten deletion rapidly induced terminal mammary epithelial differentiation accompanied by the synthesis of milk despite the absence of lobuloalveolar development. Surprisingly, we found that mammary differentiation was due to the PI3K-Akt-dependent synthesis and secretion of autocrine prolactin and downstream activation of the prolactin receptor (Prlr)-Jak-Stat5 pathway. Consistent with this, Akt-induced mammary differentiation was abrogated in Prl(-/-), Prlr(-/-), and Stat5(-/-) mice. Furthermore, cells treated with conditioned medium from mammary glands in which Akt had been activated underwent rapid Stat5 phosphorylation in a manner that was blocked by inhibition of Jak2, treatment with an anti-Prl antibody, or deletion of the prolactin gene. Demonstrating a physiological requirement for autocrine prolactin, mammary glands from lactation-defective Akt1(-/-);Akt2(+/-) mice failed to express autocrine prolactin or activate Stat5 during late pregnancy despite normal levels of circulating serum prolactin and pituitary prolactin production. Our findings reveal that PI3K-Akt pathway activation is necessary and sufficient to induce autocrine prolactin production in the mammary gland, Stat5 activation, and terminal mammary epithelial differentiation, even in the absence of the normal developmental program that prepares the mammary gland for lactation. Together, these findings identify a function for autocrine prolactin during normal development and demonstrate its endogenous regulation by the PI3K-Akt pathway.
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Affiliation(s)
- Chien-Chung Chen
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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262
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Bradtmöller M, Hartmann C, Zietsch J, Jäschke S, Mautner VF, Kurtz A, Park SJ, Baier M, Harder A, Reuss D, von Deimling A, Heppner FL, Holtkamp N. Impaired Pten expression in human malignant peripheral nerve sheath tumours. PLoS One 2012; 7:e47595. [PMID: 23139750 PMCID: PMC3490977 DOI: 10.1371/journal.pone.0047595] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 09/17/2012] [Indexed: 12/15/2022] Open
Abstract
Malignant peripheral nerve sheath tumours (MPNST) are aggressive sarcomas that develop in about 10% of patients with the genetic disease neurofibromatosis type 1 (NF1). Molecular alterations contributing to MPNST formation have only partially been resolved. Here we examined the role of Pten, a key regulator of the Pi3k/Akt/mTOR pathway, in human MPNST and benign neurofibromas. Immunohistochemistry showed that Pten expression was significantly lower in MPNST (n = 16) than in neurofibromas (n = 16) and normal nervous tissue. To elucidate potential mechanisms for Pten down-regulation or Akt/mTOR activation in MPNST we performed further experiments. Mutation analysis revealed absence of somatic mutations in PTEN (n = 31) and PIK3CA (n = 38). However, we found frequent PTEN promotor methylation in primary MPNST (11/26) and MPNST cell lines (7/8) but not in benign nerve sheath tumours. PTEN methylation was significantly associated with early metastasis. Moreover, we detected an inverse correlation of Pten-regulating miR-21 and Pten protein levels in MPNST cell lines. The examination of NF1−/− and NF1+/+Schwann cells and fibroblasts showed that Pten expression is not regulated by NF1. To determine the significance of Pten status for treatment with the mTOR inhibitor rapamycin we treated 5 MPNST cell lines with rapamycin. All cell lines were sensitive to rapamycin without a significant correlation to Pten levels. When rapamycin was combined with simvastatin a synergistic anti-proliferative effect was achieved. Taken together we show frequent loss/reduction of Pten expression in MPNST and provide evidence for the involvement of multiple Pten regulating mechanisms.
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Affiliation(s)
- Maren Bradtmöller
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Christian Hartmann
- Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-University Heidelberg, and Clinical Cooperation Unit Neuropathology, German Cancer Research Center, Heidelberg, Germany
| | - Jan Zietsch
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Sebastian Jäschke
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Victor-F Mautner
- Department of Maxillofacial Surgery, University Hospital Eppendorf, Hamburg, Germany
| | - Andreas Kurtz
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany
- College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Su-Jin Park
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Baier
- Project Neurodegenerative Diseases, Robert-Koch-Institute, Berlin, Germany
| | - Anja Harder
- Institute of Neuropathology, University Hospital Münster, Münster, Germany
| | - David Reuss
- Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-University Heidelberg, and Clinical Cooperation Unit Neuropathology, German Cancer Research Center, Heidelberg, Germany
| | - Andreas von Deimling
- Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-University Heidelberg, and Clinical Cooperation Unit Neuropathology, German Cancer Research Center, Heidelberg, Germany
| | - Frank L. Heppner
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Nikola Holtkamp
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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263
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The nuclear receptor TLX is required for gliomagenesis within the adult neurogenic niche. Mol Cell Biol 2012; 32:4811-20. [PMID: 23028043 DOI: 10.1128/mcb.01122-12] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Neural stem cells (NSCs) continually generate functional neurons in the adult brain. Due to their ability to proliferate, deregulated NSCs or their progenitors have been proposed as the cells of origin for a number of primary central nervous system neoplasms, including infiltrating gliomas. The orphan nuclear receptor TLX is required for proliferation of adult NSCs, and its upregulation promotes brain tumor formation. However, it is unknown whether TLX is required for gliomagenesis. We examined the genetic interactions between TLX and several tumor suppressors, as well as the role of TLX-dependent NSCs during gliomagenesis, using mouse models. Here, we show that TLX is essential for the proliferation of adult NSCs with a single deletion of p21, p53, or Pten or combined deletion of Pten and p53. While brain tumors still form in Tlx mutant mice, these tumors are less infiltrative and rarely associate with the adult neurogenic niches, suggesting a non-stem-cell origin. Taken together, these results indicate a critical role for TLX in NSC-dependent gliomagenesis and implicate TLX as a therapeutic target to inhibit the development of NSC-derived brain tumors.
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264
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Kim HS, Woolard K, Lai C, Bauer PO, Maric D, Song H, Li A, Kotliarova S, Zhang W, Fine HA. Gliomagenesis arising from Pten- and Ink4a/Arf-deficient neural progenitor cells is mediated by the p53-Fbxw7/Cdc4 pathway, which controls c-Myc. Cancer Res 2012; 72:6065-75. [PMID: 22986743 DOI: 10.1158/0008-5472.can-12-2594] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Glioblastoma multiforme is the most common type of primary malignant brain tumor and may arise from a cell with neural stem-like properties. Deregulation of the retinoblastoma, phosphoinositide-3 kinase (PI3K), and p53 pathways are molecular hallmarks of this disease. Recent work has shown that p53(-/-)Pten(-/-) mice form gliomas in a c-Myc-dependent manner. To explore the role of the INK4A/ARF locus and Pten deletions in gliomagenesis, we generated Pten(-/-)Ink4a/Arf(-/-) mouse neural stem cells (mNSC) and such cells were highly proliferative, self-renewing, relatively refractory to differentiation, and induced both low- and high-grade glioma formation in vivo. In contrast to p53(-/-) Pten(-/-) mNSCs, however, Pten(-/-)Ink4a/Arf(-/-) mNSCs do not express appreciable levels of c-Myc in vitro, although glioma stem cells derived from thesecells did. Sequencing of Pten(-/-)Ink4a/Arf(-/-) mNSC-derived tumors revealed spontaneous mutations in Tp53 in vivo with subsequent downregulation of Fbxw7. Expression of p53 mutants in Pten(-/-)Ink4a/Arf(-/-) mNSC or knockdown of Fbxw7 resulted in reexpression of c-Myc with enhanced Pten(-/-)Ink4a/Arf(-/-) mNSC tumorigenecity. We propose that p53 mutations contribute to gliomagenesis by both allowing the overexpression of c-Myc through downregulation of Fbxw7 and by protecting against c-Myc-induced apoptosis.
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Affiliation(s)
- Hong Sug Kim
- Neuro-Oncology Branch, National Cancer Institute, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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265
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Smith JM, Xu J, Powell EM. Age dependent forebrain structural changes in mice deficient in the autism associated gene Met tyrosine kinase. Neuroimage Clin 2012; 1:66-74. [PMID: 24179738 PMCID: PMC3757733 DOI: 10.1016/j.nicl.2012.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/13/2012] [Accepted: 09/03/2012] [Indexed: 01/06/2023]
Abstract
The MET tyrosine kinase has been identified as a susceptibility gene in patients with autism spectrum disorders. MET is expressed in the forebrain during prenatal and postnatal development. After birth, MET participates in dendritic outgrowth and circuit formation. Alterations in neuronal development, particularly in the cerebral cortex, may contribute to the pathology of developmental disorders, including autism. Patients with autism can exhibit abnormal cortical volumes and head circumferences. We tested the hypothesis that impaired Met signaling during development alters forebrain structure. We have utilized a conditional mutant mouse line which expresses a kinase-dead Met restricted to the cerebral cortex and hippocampal structures. In these mice, we have used magnetic resonance imaging (MRI) to analyze the structure of the cerebral cortex and related structures across postnatal development. We found that the rostral cortex, caudal hippocampus, dorsal striatum, thalamus, and corpus callosum were all larger in adult, but not juvenile, mutant mice relative to control mice. The specificity of the changes suggests that aberrant expansion of the forebrain is consistent with continued axonal and dendritic growth, potentially leading to improper circuit formation and maintenance.
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Key Words
- ANOVA, analysis of variance
- Autism
- CC, corpus callosum
- Corpus callosum
- Frontal cortex
- H,hipp, hippocampus
- HGF, hepatocyte growth factor
- K–S, Kolmogorov–Smirnov
- MRI
- MRI, magnetic resonance imaging
- Met tyrosine kinase
- Mouse
- P, postnatal day
- PCR, polymerase chain reaction
- RARE, rapid acquisition relaxation enhancement
- SEM, standard error of the mean
- bp, base pairs
- ctx, cerebral cortex
- mm, millimeter
- str, striatum
- th,thal, thalamus
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Affiliation(s)
- Jacob M. Smith
- Program in Neuroscience, Graduate Program in Life Sciences, Graduate School, University of Maryland, Baltimore, MD, USA
| | - Jennifer Xu
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Elizabeth M. Powell
- Program in Neuroscience, Graduate Program in Life Sciences, Graduate School, University of Maryland, Baltimore, MD, USA
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
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266
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Kim TH, Song J, Alcantara Llaguno SR, Murnan E, Liyanarachchi S, Palanichamy K, Yi JY, Viapiano MS, Nakano I, Yoon SO, Wu H, Parada LF, Kwon CH. Suppression of peroxiredoxin 4 in glioblastoma cells increases apoptosis and reduces tumor growth. PLoS One 2012; 7:e42818. [PMID: 22916164 PMCID: PMC3419743 DOI: 10.1371/journal.pone.0042818] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 07/12/2012] [Indexed: 11/18/2022] Open
Abstract
Glioblastoma multiforme (GBM), the most common and aggressive primary brain malignancy, is incurable despite the best combination of current cancer therapies. For the development of more effective therapies, discovery of novel candidate tumor drivers is urgently needed. Here, we report that peroxiredoxin 4 (PRDX4) is a putative tumor driver. PRDX4 levels were highly increased in a majority of human GBMs as well as in a mouse model of GBM. Reducing PRDX4 expression significantly decreased GBM cell growth and radiation resistance in vitro with increased levels of ROS, DNA damage, and apoptosis. In a syngenic orthotopic transplantation model, Prdx4 knockdown limited GBM infiltration and significantly prolonged mouse survival. These data suggest that PRDX4 can be a novel target for GBM therapies in the future.
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Affiliation(s)
- Tae Hyong Kim
- Dardinger Center for Neuro-Oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
- Solid Tumor Program, The James Comprehensive Cancer Center, the Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Jieun Song
- Dardinger Center for Neuro-Oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
- Solid Tumor Program, The James Comprehensive Cancer Center, the Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Sheila R. Alcantara Llaguno
- Department of Developmental Biology, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Eric Murnan
- Dardinger Center for Neuro-Oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
- Solid Tumor Program, The James Comprehensive Cancer Center, the Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Sandya Liyanarachchi
- Human Cancer Genetics Program and Biomedical Informatics Shared Resources, The James Comprehensive Cancer Center, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Kamalakannan Palanichamy
- Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Ji-Yeun Yi
- Dardinger Center for Neuro-Oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
- Solid Tumor Program, The James Comprehensive Cancer Center, the Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Mariano Sebastian Viapiano
- Dardinger Center for Neuro-Oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Ichiro Nakano
- Dardinger Center for Neuro-Oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Sung Ok Yoon
- Department of Molecular and Cellular Biochemistry and the James Comprehensive Cancer Center, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
| | - Hong Wu
- Department of Molecular and Medical Pharmacology and Institute for Molecular Medicine, School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Luis F. Parada
- Department of Developmental Biology, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Chang-Hyuk Kwon
- Dardinger Center for Neuro-Oncology and Neurosciences, Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
- Solid Tumor Program, The James Comprehensive Cancer Center, the Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America
- * E-mail:
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267
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Terrien E, Chaffotte A, Lafage M, Khan Z, Préhaud C, Cordier F, Simenel C, Delepierre M, Buc H, Lafon M, Wolff N. Interference with the PTEN-MAST2 interaction by a viral protein leads to cellular relocalization of PTEN. Sci Signal 2012; 5:ra58. [PMID: 22894835 DOI: 10.1126/scisignal.2002941] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PTEN (phosphatase and tensin homolog deleted on chromosome 10) and MAST2 (microtubule-associated serine and threonine kinase 2) interact with each other through the PDZ domain of MAST2 (MAST2-PDZ) and the carboxyl-terminal (C-terminal) PDZ domain-binding site (PDZ-BS) of PTEN. These two proteins function as negative regulators of cell survival pathways, and silencing of either one promotes neuronal survival. In human neuroblastoma cells infected with rabies virus (RABV), the C-terminal PDZ domain of the viral glycoprotein (G protein) can target MAST2-PDZ, and RABV infection triggers neuronal survival in a PDZ-BS-dependent fashion. These findings suggest that the PTEN-MAST2 complex inhibits neuronal survival and that viral G protein disrupts this complex through competition with PTEN for binding to MAST2-PDZ. We showed that the C-terminal sequences of PTEN and the viral G protein bound to MAST2-PDZ with similar affinities. Nuclear magnetic resonance structures of these complexes exhibited similar large interaction surfaces, providing a structural basis for their binding specificities. Additionally, the viral G protein promoted the nuclear exclusion of PTEN in infected neuroblastoma cells in a PDZ-BS-dependent manner without altering total PTEN abundance. These findings suggest that formation of the PTEN-MAST2 complex is specifically affected by the viral G protein and emphasize how disruption of a critical protein-protein interaction regulates intracellular PTEN trafficking. In turn, the data show how the viral protein might be used to decipher the underlying molecular mechanisms and to clarify how the subcellular localization of PTEN regulates neuronal survival.
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Affiliation(s)
- Elouan Terrien
- Institut Pasteur, Unité de Résonance Magnétique Nucléaire des Biomolécules, Département de Biologie Structurale et Chimie, F-75015 Paris, France
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268
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Ostrakhovitch EA, Semenikhin OA. The role of redox environment in neurogenic development. Arch Biochem Biophys 2012; 534:44-54. [PMID: 22910298 DOI: 10.1016/j.abb.2012.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 07/19/2012] [Accepted: 08/03/2012] [Indexed: 10/28/2022]
Abstract
The dynamic changes of cellular redox elements during neurogenesis allow the control of specific programs for selective lineage progression. There are many redox couples that influence the cellular redox state. The shift from a reduced to an oxidized state and vice versa may act as a cellular switch mechanism of stem cell mode of action from proliferation to differentiation. The redox homeostasis ensures proper functioning of redox-sensitive signaling pathways through oxidation/reduction of critical cysteine residues on proteins involved in signal transduction. This review presents the current knowledge on the relation between changes in the cellular redox environment and stem cell programming in the course of commitment to a restricted neural lineage, focusing on in vivo neurogenesis and in vitro neuronal differentiation. The first two sections outline the main systems that control the intracellular redox environment and make it more oxidative or reductive. The last section provides the background on redox-sensitive signaling pathways that regulate neurogenesis.
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Affiliation(s)
- E A Ostrakhovitch
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7.
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269
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Ro SH, Liu D, Yeo H, Paik JH. FoxOs in neural stem cell fate decision. Arch Biochem Biophys 2012; 534:55-63. [PMID: 22902436 DOI: 10.1016/j.abb.2012.07.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 07/30/2012] [Accepted: 07/31/2012] [Indexed: 02/07/2023]
Abstract
Neural stem cells (NSCs) persist over the lifespan of mammals to give rise to committed progenitors and their differentiated cells in order to maintain the brain homeostasis. To this end, NSCs must be able to self-renew and otherwise maintain their quiescence. Suppression of aberrant proliferation or undesired differentiation is crucial to preclude either malignant growth or precocious depletion of NSCs. The PI3K-Akt-FoxO signaling pathway plays a central role in the regulation of multiple stem cells including one in the mammalian brain. In particular, members of FoxO family transcription factors are highly expressed in these stem cells. As an important downstream effector of growth, differentiation, and stress stimuli, mammalian FoxO transcription factor family controls cellular proliferation, oxidative stress response, homeostasis, and eventual maintenance of long-term repopulating potential. The review will focus on the current understanding of FoxO function in NSCs as well as discuss their biological activities that contribute to determining neural stem cell fate.
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Affiliation(s)
- Seung-Hyun Ro
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065, USA
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270
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Zhu G, Chow LML, Bayazitov IT, Tong Y, Gilbertson RJ, Zakharenko SS, Solecki DJ, Baker SJ. Pten deletion causes mTorc1-dependent ectopic neuroblast differentiation without causing uniform migration defects. Development 2012; 139:3422-31. [PMID: 22874917 DOI: 10.1242/dev.083154] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neuronal precursors, generated throughout life in the subventricular zone, migrate through the rostral migratory stream to the olfactory bulb where they differentiate into interneurons. We found that the PI3K-Akt-mTorc1 pathway is selectively inactivated in migrating neuroblasts in the subventricular zone and rostral migratory stream, and activated when these cells reach the olfactory bulb. Postnatal deletion of Pten caused aberrant activation of the PI3K-Akt-mTorc1 pathway and an enlarged subventricular zone and rostral migratory stream. This expansion was caused by premature termination of migration and differentiation of neuroblasts and was rescued by inhibition of mTorc1. This phenotype is reminiscent of lamination defects caused by Pten deletion in developing brain that were previously described as defective migration. However, live imaging in acute slices showed that Pten deletion did not cause a uniform defect in the mechanics of directional neuroblast migration. Instead, a subpopulation of Pten-null neuroblasts showed minimal movement and altered morphology associated with differentiation, whereas the remainder showed unimpeded directional migration towards the olfactory bulb. Therefore, migration defects of Pten-null neurons might be secondary to ectopic differentiation.
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Affiliation(s)
- Guo Zhu
- Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, TN 38105, USA
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271
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Rico C, Laguë MN, Lefèvre P, Tsoi M, Dodelet-Devillers A, Kumar V, Lapointe E, Paquet M, Nadeau MÈ, Boerboom D. Pharmacological targeting of mammalian target of rapamycin inhibits ovarian granulosa cell tumor growth. Carcinogenesis 2012; 33:2283-92. [PMID: 22871496 DOI: 10.1093/carcin/bgs263] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Few targeted therapies have been developed for ovarian granulosa cell tumor (GCT), even though it represents 5% of all malignant ovarian tumors in women. As misregulation of PI3K/AKT signaling has been implicated in GCT development, we hypothesized that the AKT signaling effector mammalian target of rapamycin (mTOR) may play a role in the pathogenesis of GCT and could represent a therapeutic target. Analyses of human GCT samples showed an increase in protein levels of mTOR and its downstream effectors RPS6KB1, RPS6, eIF4B and PPARG relative to normal granulosa cells, suggestive of an increase in mTOR pathway activity and increased translational activity and/or protein stability. We next sought to evaluate mTOR as a GCT therapeutic target using the Pten (tm1Hwu/tmiHwu);Ctnnb1 (tm1Mmt/+);Amhr2 (tm3(cre)Bhr/+) (PCA) mouse model, in which mTOR, RPS6KB1, eIF4B and PPARG are upregulated in tumor cells in a manner similar to human GCT. Treatment of PCA mice with the mTOR-specific inhibitor everolimus reduced tumor growth rate (1.5-fold; P < 0.05) and also reduced total tumor burden (4.7-fold; P < 0.05) and increased survival rate (78 versus 44% in the vehicle group) in a PCA surgical model of GCT peritoneal carcinomatosis. Everolimus decreased tumor cell proliferation and tumor cell volume relative to controls (P < 0.05), whereas apoptosis was unaffected. Phosphorylation of RPS6KB1 and RPS6 were decreased (P < 0.05) by everolimus, but RPS6KB1, RPS6, eIF4B and PPARG expressions were not affected. These results suggest that mTOR is a valid and clinically useful pharmacological target for the treatment of GCT, although its inhibition does not reverse all consequences of aberrant PI3K/AKT signaling in the PCA model.
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Affiliation(s)
- Charlène Rico
- Centre de Recherche en Reproduction animale, Université de Montréal, St-Hyacinthe, Québec J2S 7C6, Canada
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272
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Pten deletion in adult hippocampal neural stem/progenitor cells causes cellular abnormalities and alters neurogenesis. J Neurosci 2012; 32:5880-90. [PMID: 22539849 DOI: 10.1523/jneurosci.5462-11.2012] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adult neurogenesis persists throughout life in restricted brain regions in mammals and is affected by various physiological and pathological conditions. The tumor suppressor gene Pten is involved in adult neurogenesis and is mutated in a subset of autism patients with macrocephaly; however, the link between the role of PTEN in adult neurogenesis and the etiology of autism has not been studied before. Moreover, the role of hippocampus, one of the brain regions where adult neurogenesis occurs, in development of autism is not clear. Here, we show that ablating Pten in adult neural stem cells in the subgranular zone of hippocampal dentate gyrus results in higher proliferation rate and accelerated differentiation of the stem/progenitor cells, leading to depletion of the neural stem cell pool and increased differentiation toward the astrocytic lineage at later stages. Pten-deleted stem/progenitor cells develop into hypertrophied neurons with abnormal polarity. Additionally, Pten mutant mice have macrocephaly and exhibit impairment in social interactions and seizure activity. Our data reveal a novel function for PTEN in adult hippocampal neurogenesis and indicate a role in the pathogenesis of abnormal social behaviors.
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273
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Sakata H, Niizuma K, Wakai T, Narasimhan P, Maier CM, Chan PH. Neural stem cells genetically modified to overexpress cu/zn-superoxide dismutase enhance amelioration of ischemic stroke in mice. Stroke 2012; 43:2423-9. [PMID: 22713489 DOI: 10.1161/strokeaha.112.656900] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND PURPOSE The harsh host brain microenvironment caused by production of reactive oxygen species after ischemic reperfusion injury offers a significant challenge to survival of transplanted neural stem cells (NSCs) after ischemic stroke. Copper/zinc-superoxide dismutase (SOD1) is a specific antioxidant enzyme that counteracts superoxide anions. We have investigated whether genetic manipulation to overexpress SOD1 enhances survival of grafted stem cells and accelerates amelioration of ischemic stroke. METHODS NSCs genetically modified to overexpress or downexpress SOD1 were administered intracerebrally 2 days after transient middle cerebral artery occlusion. Histological and behavioral tests were examined from Days 0 to 28 after stroke. RESULTS Overexpression of SOD1 suppressed production of superoxide anions after ischemic reperfusion injury and reduced NSC death after transplantation. In contrast, downexpression of SOD1 promoted superoxide generation and increased oxidative stress-mediated NSC death. Transplantation of SOD1-overexpressing NSCs enhanced angiogenesis in the ischemic border zone through upregulation of vascular endothelial growth factor. Moreover, grafted SOD1-overexpressing NSCs reduced infarct size and improved behavioral performance compared with NSCs that were not genetically modified. CONCLUSIONS Our findings reveal a strong involvement of SOD1 expression in NSC survival after ischemic reperfusion injury. We propose that conferring antioxidant properties on NSCs by genetic manipulation of SOD1 is a potential approach for enhancing the effectiveness of cell transplantation therapy in ischemic stroke.
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Affiliation(s)
- Hiroyuki Sakata
- Neurosurgical Laboratories, Stanford University, 1201 Welch Road, MSLS #P314, Stanford, CA 94305-5487, USA
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274
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Sinor-Anderson A, Lillien L. Akt1 interacts with epidermal growth factor receptors and hedgehog signaling to increase stem/transit amplifying cells in the embryonic mouse cortex. Dev Neurobiol 2012; 71:759-71. [PMID: 21312341 DOI: 10.1002/dneu.20878] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A subset of precursors in the embryonic mouse cortex and in neurospheres expresses a higher level of the serine/threonine kinase Akt1 than neighboring precursors. We reported previously that the functional significance of high Akt1 expression was enhanced Akt1 activity, resulting in an increase in survival, proliferation, and self-renewal of multipotent stem/transit amplifying cells. Akt1 can interact with a number of signaling pathways, but the extrinsic factors that are required for specific effects of elevated Akt1 expression have not been identified. In this study we addressed the contributions of signaling via epidermal growth factor (EGF) and hedgehog (Hh) receptors. In EGF receptor-null precursors or following transient inhibition of EGF receptor tyrosine kinase activity, elevating Akt1 by retroviral transduction could still increase survival and proliferation but could not increase self-renewal. We also found that elevated Akt1 expression induced the expression of EGF receptors (EGFRs) in wild-type precursors. Several extrinsic factors, including Shh, can induce EGFR expression by cortical precursors, and we found that elevating Akt1 allowed them to respond to a subthreshold concentration of Shh to induce EGFRs. In precursors that lack the Hh receptor smoothened, however, elevating Akt1 did not increase EGFR expression or self-renewal, though it could still stimulate proliferation. These findings suggest that a subset of precursors in the embryonic cortex that express an elevated level of Akt1 can respond to lower concentrations of Shh than neighboring precursors, resulting in an increase in their expression of EGFRs. Signaling via EGFRs is required for their self-renewal.
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Affiliation(s)
- Amy Sinor-Anderson
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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275
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Lima FRS, Kahn SA, Soletti RC, Biasoli D, Alves T, da Fonseca ACC, Garcia C, Romão L, Brito J, Holanda-Afonso R, Faria J, Borges H, Moura-Neto V. Glioblastoma: therapeutic challenges, what lies ahead. Biochim Biophys Acta Rev Cancer 2012; 1826:338-49. [PMID: 22677165 DOI: 10.1016/j.bbcan.2012.05.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 12/17/2022]
Abstract
Glioblastoma (GBM) is one of the most aggressive human cancers. Despite current advances in multimodality therapies, such as surgery, radiotherapy and chemotherapy, the outcome for patients with high grade glioma remains fatal. The knowledge of how glioma cells develop and depend on the tumor environment might open opportunities for new therapies. There is now a growing awareness that the main limitations in understanding and successfully treating GBM might be bypassed by the identification of a distinct cell type that has defining properties of somatic stem cells, as well as cancer-initiating capacity - brain tumor stem cells, which could represent a therapeutic target. In addition, experimental studies have demonstrated that the combination of antiangiogenic therapy, based on the disruption of tumor blood vessels, with conventional chemotherapy generates encouraging results. Emerging reports have also shown that microglial cells can be used as therapeutic vectors to transport genes and/or substances to the tumor site, which opens up new perspectives for the development of GBM therapies targeting microglial cells. Finally, recent studies have shown that natural toxins can be conjugated to drugs that bind to overexpressed receptors in cancer cells, generating targeted-toxins to selectively kill cancer cells. These targeted-toxins are highly effective against radiation- and chemotherapy-resistant cancer cells, making them good candidates for clinical trials in GBM patients. In this review, we discuss recent studies that reveal new possibilities of GBM treatment taking into account cancer stem cells, angiogenesis, microglial cells and drug delivery in the development of new targeted-therapies.
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Affiliation(s)
- Flavia R S Lima
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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276
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PTEN signaling in autism spectrum disorders. Curr Opin Neurobiol 2012; 22:873-9. [PMID: 22664040 DOI: 10.1016/j.conb.2012.05.004] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/07/2012] [Accepted: 05/08/2012] [Indexed: 12/20/2022]
Abstract
PTEN germline mutations are found in a small subset of children diagnosed with autism spectrum disorder (ASD) and accompanying macrocephaly. In this review, we discuss recent advances that offer insight into the pathogenesis of this subgroup of autism patients. We provide an overview of how disrupting PTEN function influences neuronal cells, and describe efforts to decipher the cellular mechanisms associated with altered social behaviors. We discuss the PTEN downstream signaling pathways that likely mediate these cellular and behavioral effects. In addition, emerging data suggest that PTEN mutation can synergize with mutations in other autism susceptibility genes to contribute to the development of autistic behaviors. These studies extend our knowledge of PTEN and the PTEN signaling pathway, and offer molecular and cellular clues to better understand the etiology of ASDs.
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277
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Kazdoba TM, Sunnen CN, Crowell B, Lee GH, Anderson AE, D'Arcangelo G. Development and characterization of NEX- Pten, a novel forebrain excitatory neuron-specific knockout mouse. Dev Neurosci 2012; 34:198-209. [PMID: 22572802 DOI: 10.1159/000337229] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 02/13/2012] [Indexed: 01/15/2023] Open
Abstract
The phosphatase and tensin homolog located on chromosome 10 (PTEN) suppresses the activity of the phosphoinositide-3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway, a signaling cascade critically involved in the regulation of cell proliferation and growth. Human patients carrying germ line PTEN mutations have an increased predisposition to tumors, and also display a variety of neurological symptoms and increased risk of epilepsy and autism, implicating PTEN in neuronal development and function. Consistently, loss of Pten in mouse neural cells results in ataxia, seizures, cognitive abnormalities, increased soma size and synaptic abnormalities. To better understand how Pten regulates the excitability of principal forebrain neurons, a factor that is likely to be altered in cognitive disorders, epilepsy and autism, we generated a novel conditional knockout mouse line (NEX-Pten) in which Cre, under the control of the NEX promoter, drives the deletion of Pten specifically in early postmitotic, excitatory neurons of the developing forebrain. Homozygous mutant mice exhibited a massive enlargement of the forebrain, and died shortly after birth due to excessive mTOR activation. Analysis of the neonatal cerebral cortex further identified molecular defects resulting from Pten deletion that likely affect several aspects of neuronal development and excitability.
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Affiliation(s)
- Tatiana M Kazdoba
- Department of Cell Biology and Neuroscience, The State University of New Jersey, Piscataway, NJ 08854, USA
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278
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Abstract
Glioma is the most frequent primary brain tumor of adults that has a presumably glial origin. Although our knowledge regarding molecular mechanisms and signaling pathways involved in gliomagenesis has increased immensely during the past decade, high-grade glioma remains a lethal disease with dismal prognosis. The failure of current therapies has to a large extent been ascribed the functional heterogeneity of glioma cells. One reason for this heterogeneity is most certainly the large number of variations in genetic alterations that can be found in high-grade gliomas. Another factor that may influence glioma heterogeneity could be the cell type from which the glioma is initiated. The cell of origin for glioma is still undefined, and additional knowledge about this issue may prove critical for a more complete understanding of glioma biology. Based on information from patients, developmental biology, and experimental glioma models, the most putative target cells include astrocytes, neural stem cells, and oligodendrocyte precursor cells, which are all discussed in more detail in this article. Animal modeling of glioma suggests that these three cell types have the capability to be the origin of glioma, and we have reason to believe that, depending on the initiating cell type, prognosis and response to therapy may be significantly different. Thus, it is essential to explore further the role of cellular origin in glioma.
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Affiliation(s)
- Yiwen Jiang
- Uppsala University, Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, SE-75185 Uppsala, Sweden
| | - Lene Uhrbom
- Uppsala University, Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, SE-75185 Uppsala, Sweden
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279
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Gene expression profiling of neural stem cells and their neuronal progeny reveals IGF2 as a regulator of adult hippocampal neurogenesis. J Neurosci 2012; 32:3376-87. [PMID: 22399759 DOI: 10.1523/jneurosci.4248-11.2012] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Neural stem cells (NSCs) generate neurons throughout life in the hippocampal dentate gyrus (DG). How gene expression signatures differ among NSCs and immature neurons remains largely unknown. We isolated NSCs and their progeny in the adult DG using transgenic mice expressing a GFP reporter under the control of the Sox2 promoter (labeling NSCs) and transgenic mice expressing a DsRed reporter under the control of the doublecortin (DCX) promoter (labeling immature neurons). Transcriptome analyses revealed distinct gene expression profiles between NSCs and immature neurons. Among the genes that were expressed at significantly higher levels in DG NSCs than in immature neurons was the growth factor insulin-like growth factor 2 (IGF2). We show that IGF2 selectively controls proliferation of DG NSCs in vitro and in vivo through AKT-dependent signaling. Thus, by gene expression profiling of NSCs and their progeny, we have identified IGF2 as a novel regulator of adult neurogenesis.
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280
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Shenoy S, Shekhar P, Heinrich F, Daou MC, Gericke A, Ross AH, Lösche M. Membrane association of the PTEN tumor suppressor: molecular details of the protein-membrane complex from SPR binding studies and neutron reflection. PLoS One 2012; 7:e32591. [PMID: 22505997 PMCID: PMC3323581 DOI: 10.1371/journal.pone.0032591] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 01/29/2012] [Indexed: 12/03/2022] Open
Abstract
The structure and function of the PTEN phosphatase is investigated by studying its membrane affinity and localization on in-plane fluid, thermally disordered synthetic membrane models. The membrane association of the protein depends strongly on membrane composition, where phosphatidylserine (PS) and phosphatidylinositol diphosphate (PI(4,5)P2) act pronouncedly synergistic in pulling the enzyme to the membrane surface. The equilibrium dissociation constants for the binding of wild type (wt) PTEN to PS and PI(4,5)P2 were determined to be Kd∼12 µM and 0.4 µM, respectively, and Kd∼50 nM if both lipids are present. Membrane affinities depend critically on membrane fluidity, which suggests multiple binding sites on the protein for PI(4,5)P2. The PTEN mutations C124S and H93R show binding affinities that deviate strongly from those measured for the wt protein. Both mutants bind PS more strongly than wt PTEN. While C124S PTEN has at least the same affinity to PI(4,5)P2 and an increased apparent affinity to PI(3,4,5)P3, due to its lack of catalytic activity, H93R PTEN shows a decreased affinity to PI(4,5)P2 and no synergy in its binding with PS and PI(4,5)P2. Neutron reflection measurements show that the PTEN phosphatase “scoots" along the membrane surface (penetration <5 Å) but binds the membrane tightly with its two major domains, the C2 and phosphatase domains, as suggested by the crystal structure. The regulatory C-terminal tail is most likely displaced from the membrane and organized on the far side of the protein, ∼60 Å away from the bilayer surface, in a rather compact structure. The combination of binding studies and neutron reflection allows us to distinguish between PTEN mutant proteins and ultimately may identify the structural features required for membrane binding and activation of PTEN.
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Affiliation(s)
- Siddharth Shenoy
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Prabhanshu Shekhar
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Frank Heinrich
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
| | - Marie-Claire Daou
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Arne Gericke
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Alonzo H. Ross
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Mathias Lösche
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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281
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Song MS, Salmena L, Pandolfi PP. The functions and regulation of the PTEN tumour suppressor. Nat Rev Mol Cell Biol 2012; 13:283-96. [PMID: 22473468 DOI: 10.1038/nrm3330] [Citation(s) in RCA: 1450] [Impact Index Per Article: 120.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The importance of the physiological function of phosphatase and tensin homologue (PTEN) is illustrated by its frequent disruption in cancer. By suppressing the phosphoinositide 3-kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) pathway through its lipid phosphatase activity, PTEN governs a plethora of cellular processes including survival, proliferation, energy metabolism and cellular architecture. Consequently, mechanisms regulating PTEN expression and function, including transcriptional regulation, post-transcriptional regulation by non-coding RNAs, post-translational modifications and protein-protein interactions, are all altered in cancer. The repertoire of PTEN functions has recently been expanded to include phosphatase-independent activities and crucial functions within the nucleus. Our increasing knowledge of PTEN and pathologies in which its function is altered will undoubtedly inform the rational design of novel therapies.
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Affiliation(s)
- Min Sup Song
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Department of Medicine and Pathology, Harvard Medical School, Boston, Massachuchetts 02215, USA.
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282
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Chow ML, Pramparo T, Winn ME, Barnes CC, Li HR, Weiss L, Fan JB, Murray S, April C, Belinson H, Fu XD, Wynshaw-Boris A, Schork NJ, Courchesne E. Age-dependent brain gene expression and copy number anomalies in autism suggest distinct pathological processes at young versus mature ages. PLoS Genet 2012; 8:e1002592. [PMID: 22457638 PMCID: PMC3310790 DOI: 10.1371/journal.pgen.1002592] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 01/22/2012] [Indexed: 01/09/2023] Open
Abstract
Autism is a highly heritable neurodevelopmental disorder, yet the genetic underpinnings of the disorder are largely unknown. Aberrant brain overgrowth is a well-replicated observation in the autism literature; but association, linkage, and expression studies have not identified genetic factors that explain this trajectory. Few studies have had sufficient statistical power to investigate whole-genome gene expression and genotypic variation in the autistic brain, especially in regions that display the greatest growth abnormality. Previous functional genomic studies have identified possible alterations in transcript levels of genes related to neurodevelopment and immune function. Thus, there is a need for genetic studies involving key brain regions to replicate these findings and solidify the role of particular functional pathways in autism pathogenesis. We therefore sought to identify abnormal brain gene expression patterns via whole-genome analysis of mRNA levels and copy number variations (CNVs) in autistic and control postmortem brain samples. We focused on prefrontal cortex tissue where excess neuron numbers and cortical overgrowth are pronounced in the majority of autism cases. We found evidence for dysregulation in pathways governing cell number, cortical patterning, and differentiation in young autistic prefrontal cortex. In contrast, adult autistic prefrontal cortex showed dysregulation of signaling and repair pathways. Genes regulating cell cycle also exhibited autism-specific CNVs in DNA derived from prefrontal cortex, and these genes were significantly associated with autism in genome-wide association study datasets. Our results suggest that CNVs and age-dependent gene expression changes in autism may reflect distinct pathological processes in the developing versus the mature autistic prefrontal cortex. Our results raise the hypothesis that genetic dysregulation in the developing brain leads to abnormal regional patterning, excess prefrontal neurons, cortical overgrowth, and neural dysfunction in autism. Autism is a disorder characterized by aberrant social, communication, and restricted and repetitive behaviors. It develops clinically in the first years of life. Toddlers and children with autism often exhibit early brain enlargement and excess neuron numbers in the prefrontal cortex. Adults with autism generally do not display enlargement but instead may have a smaller brain size. Thus, we investigated DNA and mRNA patterns in prefrontal cortex from young versus adult postmortem individuals with autism to identify age-related gene expression differences as well as possible genetic correlates of abnormal brain enlargement, excess neuron numbers, and abnormal functioning in this disorder. We found abnormalities in genetic pathways governing cell number, neurodevelopment, and cortical lateralization in autism. We also found that the key pathways associated with autism are different between younger and older autistic individuals. These findings suggest that dysregulated gene pathways in the early stages of neurodevelopment could lead to later behavioral and cognitive deficits associated with autism.
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Affiliation(s)
- Maggie L. Chow
- Department of Neuroscience, NIH–UCSD Autism Center of Excellence, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Tiziano Pramparo
- Department of Neuroscience, NIH–UCSD Autism Center of Excellence, School of Medicine, University of California San Diego, La Jolla, California, United States of America
- Division of Medical Genetics, Department of Pediatrics and Institute of Human Genetics, School of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Mary E. Winn
- Scripps Genomic Medicine and The Scripps Translational Sciences Institute (STSI), La Jolla, California, United States of America
- Graduate Program in Biomedical Sciences, Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Cynthia Carter Barnes
- Department of Neuroscience, NIH–UCSD Autism Center of Excellence, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Hai-Ri Li
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Lauren Weiss
- Department of Psychiatry, School of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Jian-Bing Fan
- Illumina, San Diego, California, United States of America
| | - Sarah Murray
- Scripps Genomic Medicine and The Scripps Translational Sciences Institute (STSI), La Jolla, California, United States of America
| | - Craig April
- Illumina, San Diego, California, United States of America
| | - Haim Belinson
- Division of Medical Genetics, Department of Pediatrics and Institute of Human Genetics, School of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Xiang-Dong Fu
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Anthony Wynshaw-Boris
- Division of Medical Genetics, Department of Pediatrics and Institute of Human Genetics, School of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Nicholas J. Schork
- Scripps Genomic Medicine and The Scripps Translational Sciences Institute (STSI), La Jolla, California, United States of America
- * E-mail: (NJS); (EC)
| | - Eric Courchesne
- Department of Neuroscience, NIH–UCSD Autism Center of Excellence, School of Medicine, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (NJS); (EC)
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283
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Zappaterra MW, Lehtinen MK. The cerebrospinal fluid: regulator of neurogenesis, behavior, and beyond. Cell Mol Life Sci 2012; 69:2863-78. [PMID: 22415326 DOI: 10.1007/s00018-012-0957-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 02/28/2012] [Accepted: 03/01/2012] [Indexed: 12/11/2022]
Abstract
The cerebrospinal fluid (CSF) has attracted renewed interest as an active signaling milieu that regulates brain development, homeostasis, and disease. Advances in proteomics research have enabled an improved characterization of the CSF from development through adulthood, and key neurogenic signaling pathways that are transmitted via the CSF are now being elucidated. Due to its immediate contact with neural stem cells in the developing and adult brain, the CSF's ability to swiftly distribute signals across vast distances in the central nervous system is opening avenues to novel and exciting therapeutic approaches. In this review, we will discuss the development of the choroid plexus-CSF system, and review the current literature on how the CSF actively regulates mammalian brain development, behavior, and responses to traumatic brain injury.
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Affiliation(s)
- Mauro W Zappaterra
- Department of Physical Medicine and Rehabilitation, VA Greater Los Angeles Healthcare System, 11301 Wilshire Blvd, Los Angeles, CA 90073, USA.
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284
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Alva JA, Lee GE, Escobar EE, Pyle AD. Phosphatase and tensin homolog regulates the pluripotent state and lineage fate choice in human embryonic stem cells. Stem Cells 2012; 29:1952-62. [PMID: 21948699 DOI: 10.1002/stem.748] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Understanding the intrinsic and extrinsic signals that regulate the molecular basis of the pluripotent state may improve our understanding of mammalian embryogenesis, different states of pluripotency, and our ability to tailor lineage differentiation. Although the role of the PI3K/Akt pathway in the self-renewal and maintenance of mESCs is well-established, the specific contribution of the pathway or of its negative regulator, PTEN, in the maintenance of the human pluripotent state is less understood. To explore the PI3K/AKT pathway in human embryonic stem cell (hESC) pluripotency and differentiation, we generated stable PTEN knockdown (KD) hESCs using short hairpin RNA. Similar to mESCs, we found that PTEN KD hESCs have increased self-renewal, cell survival, and proliferation over multiple passages compared to control cells. However, in contrast to mESCs, in vitro, PTEN KD hESCs differentiated inefficiently in directed differentiation assays, in part due to the continued maintenance of OCT4 and NANOG expression. In teratoma assays, PTEN KD hESCs generated tissues from the three germ layers, although with a bias toward neuroectoderm differentiation. These results demonstrate that PTEN is a key regulator of hESC growth and differentiation, and manipulation of this pathway may improve our ability to regulate and understand the pluripotent state.
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Affiliation(s)
- Jackelyn A Alva
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095, USA
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285
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Knights MJ, Kyle S, Ismail A. Characteristic features of stem cells in glioblastomas: from cellular biology to genetics. Brain Pathol 2012; 22:592-606. [PMID: 22303870 DOI: 10.1111/j.1750-3639.2012.00573.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Glioblastoma is the most common type of primary brain tumor in adults and is among the most lethal and least successfully treated solid tumors. Recently, research into the area of stem cells in brain tumors has gained momentum. However, due to the relatively new and novel hypothesis that a subpopulation of cancer cells in each malignancy has the potential for tumor initiation and repopulation, the data in this area of research are still in its infancy. This review article is aimed at attempting to bring together research carried out so far in order to build an understanding of glioblastoma stem cells (GSCs). Initially, we consider GSCs at a morphological and cellular level, and then discuss important cell markers, signaling pathways and genetics. Furthermore, we highlight the difficulties associated with what some of the evidence indicates and what collectively the studies contribute to further defining the interpretation of GSCs.
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Affiliation(s)
- Mark J Knights
- Leeds School of Medicine, University of Leeds, Leeds, UK.
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286
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Ohka F, Natsume A, Wakabayashi T. Current trends in targeted therapies for glioblastoma multiforme. Neurol Res Int 2012; 2012:878425. [PMID: 22530127 PMCID: PMC3317017 DOI: 10.1155/2012/878425] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/21/2011] [Accepted: 12/07/2011] [Indexed: 12/21/2022] Open
Abstract
Glioblastoma multiforme (GBM) is one of the most frequently occurring tumors in the central nervous system and the most malignant tumor among gliomas. Despite aggressive treatment including surgery, adjuvant TMZ-based chemotherapy, and radiotherapy, GBM still has a dismal prognosis: the median survival is 14.6 months from diagnosis. To date, many studies report several determinants of resistance to this aggressive therapy: (1) O(6)-methylguanine-DNA methyltransferase (MGMT), (2) the complexity of several altered signaling pathways in GBM, (3) the existence of glioma stem-like cells (GSCs), and (4) the blood-brain barrier. Many studies aim to overcome these determinants of resistance to conventional therapy by using various approaches to improve the dismal prognosis of GBM such as modifying TMZ administration and combining TMZ with other agents, developing novel molecular-targeting agents, and novel strategies targeting GSCs. In this paper, we review up-to-date clinical trials of GBM treatments in order to overcome these 4 hurdles and to aim at more therapeutical effect than conventional therapies that are ongoing or are about to launch in clinical settings and discuss future perspectives.
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Affiliation(s)
- Fumiharu Ohka
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Atsushi Natsume
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Toshihiko Wakabayashi
- Department of Neurosurgery, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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287
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Cell-type specific roles for PTEN in establishing a functional retinal architecture. PLoS One 2012; 7:e32795. [PMID: 22403711 PMCID: PMC3293905 DOI: 10.1371/journal.pone.0032795] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 01/31/2012] [Indexed: 11/23/2022] Open
Abstract
Background The retina has a unique three-dimensional architecture, the precise organization of which allows for complete sampling of the visual field. Along the radial or apicobasal axis, retinal neurons and their dendritic and axonal arbors are segregated into layers, while perpendicular to this axis, in the tangential plane, four of the six neuronal types form patterned cellular arrays, or mosaics. Currently, the molecular cues that control retinal cell positioning are not well-understood, especially those that operate in the tangential plane. Here we investigated the role of the PTEN phosphatase in establishing a functional retinal architecture. Methodology/Principal Findings In the developing retina, PTEN was localized preferentially to ganglion, amacrine and horizontal cells, whose somata are distributed in mosaic patterns in the tangential plane. Generation of a retina-specific Pten knock-out resulted in retinal ganglion, amacrine and horizontal cell hypertrophy, and expansion of the inner plexiform layer. The spacing of Pten mutant mosaic populations was also aberrant, as were the arborization and fasciculation patterns of their processes, displaying cell type-specific defects in the radial and tangential dimensions. Irregular oscillatory potentials were also observed in Pten mutant electroretinograms, indicative of asynchronous amacrine cell firing. Furthermore, while Pten mutant RGC axons targeted appropriate brain regions, optokinetic spatial acuity was reduced in Pten mutant animals. Finally, while some features of the Pten mutant retina appeared similar to those reported in Dscam-mutant mice, PTEN expression and activity were normal in the absence of Dscam. Conclusions/Significance We conclude that Pten regulates somal positioning and neurite arborization patterns of a subset of retinal cells that form mosaics, likely functioning independently of Dscam, at least during the embryonic period. Our findings thus reveal an unexpected level of cellular specificity for the multi-purpose phosphatase, and identify Pten as an integral component of a novel cell positioning pathway in the retina.
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288
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Schouten M, Buijink MR, Lucassen PJ, Fitzsimons CP. New Neurons in Aging Brains: Molecular Control by Small Non-Coding RNAs. Front Neurosci 2012; 6:25. [PMID: 22363255 PMCID: PMC3281214 DOI: 10.3389/fnins.2012.00025] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 01/30/2012] [Indexed: 12/12/2022] Open
Abstract
Adult neurogenesis generates functional neurons from neural stem cells present in specific brain regions. It is largely confined to two main regions: the subventricular zone of the lateral ventricle, and the subgranular zone of the dentate gyrus (DG), in the hippocampus. With age, the function of the hippocampus and particularly the DG is impaired. For instance, adult neurogenesis is decreased with aging, in both proliferating and differentiation of newborn cells, while in parallel an age-associated decline in cognitive performance is often seen. Surprisingly, the synaptogenic potential of adult-born neurons is only marginally influenced by aging. Therefore, although proliferation, differentiation, and synaptogenesis of adult-born new neurons in the DG are closely related to each other, they are differentially affected by aging. In this review we discuss the crucial roles of a novel class of recently discovered modulators of gene expression, the small non-coding RNAs, in the regulation of adult neurogenesis. Multiple small non-coding RNAs are differentially expressed in the hippocampus. In particular a subgroup of the small non-coding RNAs, the microRNAs, fine-tune the progression of adult neurogenesis. This makes small non-coding RNAs appealing candidates to orchestrate the functional alterations in adult neurogenesis and cognition associated with aging. Finally, we summarize observations that link changes in circulating levels of steroid hormones with alterations in adult neurogenesis, cognitive decline, and vulnerability to psychopathology in advanced age, and discuss a potential interplay between steroid hormone receptors and microRNAs in cognitive decline in aging individuals.
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Affiliation(s)
- Marijn Schouten
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands
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289
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Bieberich E. It's a lipid's world: bioactive lipid metabolism and signaling in neural stem cell differentiation. Neurochem Res 2012; 37:1208-29. [PMID: 22246226 DOI: 10.1007/s11064-011-0698-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 12/31/2011] [Indexed: 01/20/2023]
Abstract
Lipids are often considered membrane components whose function is to embed proteins into cell membranes. In the last two decades, studies on brain lipids have unequivocally demonstrated that many lipids have critical cell signaling functions; they are called "bioactive lipids". Pioneering work in Dr. Robert Ledeen's laboratory has shown that two bioactive brain sphingolipids, sphingomyelin and the ganglioside GM1 are major signaling lipids in the nuclear envelope. In addition to derivatives of the sphingolipid ceramide, the bioactive lipids discussed here belong to the classes of terpenoids and steroids, eicosanoids, and lysophospholipids. These lipids act mainly through two mechanisms: (1) direct interaction between the bioactive lipid and a specific protein binding partner such as a lipid receptor, protein kinase or phosphatase, ion exchanger, or other cell signaling protein; and (2) formation of lipid microdomains or rafts that regulate the activity of a group of raft-associated cell signaling proteins. In recent years, a third mechanism has emerged, which invokes lipid second messengers as a regulator for the energy and redox balance of differentiating neural stem cells (NSCs). Interestingly, developmental niches such as the stem cell niche for adult NSC differentiation may also be metabolic compartments that respond to a distinct combination of bioactive lipids. The biological function of these lipids as regulators of NSC differentiation will be reviewed and their application in stem cell therapy discussed.
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Affiliation(s)
- Erhard Bieberich
- Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, 1120 15th Street Room CA4012, Augusta, GA 30912, USA.
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290
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Liu DZ, Ander BP, Tian Y, Stamova B, Jickling GC, Davis RR, Sharp FR. Integrated analysis of mRNA and microRNA expression in mature neurons, neural progenitor cells and neuroblastoma cells. Gene 2012; 495:120-7. [PMID: 22244746 DOI: 10.1016/j.gene.2011.12.041] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 10/24/2011] [Accepted: 12/10/2011] [Indexed: 01/22/2023]
Abstract
Mature neurons (MNs), neural progenitor cells (NPCs) and neuroblastoma cells (NBCs) are all neural-derived cells. However, MNs are unable to divide once differentiated; NPCs are able to divide a limited number of times and differentiate to normal brain cell types; whereas NBCs can divide an unlimited number of times but rarely differentiate. Here, we perform whole transcriptome (mRNA, miRNA) profiling of these cell types and compare expression levels of each cell type to the others. Integrated mRNA-miRNA functional analyses reveal that: 1) several very highly expressed genes (e.g., Robo1, Nrp1, Epha3, Unc5c, Dcc, Pak3, Limk4) and a few under-expressed miRNAs (e.g., miR-152, miR-146b, miR-339-5p) in MNs are associated with one important cellular process-axon guidance; 2) some very highly expressed mitogenic pathway genes (e.g., Map2k1, Igf1r, Rara, Runx1) and under-expressed miRNAs (e.g., miR-370, miR-9, miR-672) in NBCs are associated with cancer pathways. These results provide a library of negative mRNAmiRNA networks that are likely involved in the cellular processes of differentiation and division.
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Affiliation(s)
- Da-Zhi Liu
- Department of Neurology and the M.I.N.D. Institute, University of California at Davis, Sacramento, CA 95817, USA.
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291
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Kinross KM, Montgomery KG, Kleinschmidt M, Waring P, Ivetac I, Tikoo A, Saad M, Hare L, Roh V, Mantamadiotis T, Sheppard KE, Ryland GL, Campbell IG, Gorringe KL, Christensen JG, Cullinane C, Hicks RJ, Pearson RB, Johnstone RW, McArthur GA, Phillips WA. An activating Pik3ca mutation coupled with Pten loss is sufficient to initiate ovarian tumorigenesis in mice. J Clin Invest 2012; 122:553-7. [PMID: 22214849 DOI: 10.1172/jci59309] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 11/16/2011] [Indexed: 01/03/2023] Open
Abstract
Mutations in the gene encoding the p110α subunit of PI3K (PIK3CA) that result in enhanced PI3K activity are frequently observed in human cancers. To better understand the role of mutant PIK3CA in the initiation or progression of tumorigenesis, we generated mice in which a PIK3CA mutation commonly detected in human cancers (the H1047R mutation) could be conditionally knocked into the endogenous Pik3ca locus. Activation of this mutation in the mouse ovary revealed that alone, Pik3caH1047R induced premalignant hyperplasia of the ovarian surface epithelium but no tumors. Concomitantly, we analyzed several human ovarian cancers and found PIK3CA mutations coexistent with KRAS and/or PTEN mutations, raising the possibility that a secondary defect in a co-regulator of PI3K activity may be required for mutant PIK3CA to promote transformation. Consistent with this notion, we found that Pik3caH1047R mutation plus Pten deletion in the mouse ovary led to the development of ovarian serous adenocarcinomas and granulosa cell tumors. Both mutational events were required for early, robust Akt activation. Pharmacological inhibition of PI3K/mTOR in these mice delayed tumor growth and prolonged survival. These results demonstrate that the Pik3caH1047R mutation with loss of Pten is enough to promote ovarian cell transformation and that we have developed a model system for studying possible therapies.
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Affiliation(s)
- Kathryn M Kinross
- Cancer Research Division, Peter MacCallum Cancer Centre (Peter Mac), East Melbourne, Victoria, Australia
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292
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Ichikawa-Tomikawa N, Ogawa J, Douet V, Xu Z, Kamikubo Y, Sakurai T, Kohsaka S, Chiba H, Hattori N, Yamada Y, Arikawa-Hirasawa E. Laminin α1 is essential for mouse cerebellar development. Matrix Biol 2012; 31:17-28. [PMID: 21983115 PMCID: PMC3259268 DOI: 10.1016/j.matbio.2011.09.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Revised: 09/13/2011] [Accepted: 09/16/2011] [Indexed: 11/25/2022]
Abstract
Laminin α1 (Lama1), which is a subunit of laminin-1 (laminin-111), a heterotrimeric ECM protein, is essential for embryonic development and promotes neurite outgrowth in culture. Because the deletion of Lama1 causes lethality at early embryonic stages in mice, the in vivo role of Lama1 in neural development and functions has not yet been possible to determine. In this study, we generated conditional Lama1 knockout (Lama1(CKO)) mice in the epiblast lineage using Sox2-Cre mice. These Lama1(CKO) mice survived, but displayed behavioral disorders and impaired formation of the cerebellum. Deficiency of Lama1 in the pial basement membrane of the meninges resulted in defects in the conformation of the meninges. During cerebellar development, Lama1 deficiency also caused a decrease in the proliferation and migration of granule cell precursors, disorganization of Bergmann glial fibers and endfeet, and a transient reduction in the activity of Akt. A marked reduction in numbers of dendritic processes in Purkinje cells was observed in Lama1(CKO) mice. Together, these results indicate that Lama1 is required for cerebellar development and functions.
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Affiliation(s)
- Naoki Ichikawa-Tomikawa
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Junko Ogawa
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
- National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Vanessa Douet
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Zhuo Xu
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yuji Kamikubo
- Department of Pharmacology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Takashi Sakurai
- Department of Pharmacology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Shinichi Kohsaka
- National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hideki Chiba
- Department of Basic Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yoshihiko Yamada
- National Institute of Dental and Craniofacial Research, NIH, Bethesda, Maryland, U.S.A
| | - Eri Arikawa-Hirasawa
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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293
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Davies EM, Sheffield DA, Tibarewal P, Fedele CG, Mitchell CA, Leslie NR. The PTEN and Myotubularin phosphoinositide 3-phosphatases: linking lipid signalling to human disease. Subcell Biochem 2012; 58:281-336. [PMID: 22403079 DOI: 10.1007/978-94-007-3012-0_8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Two classes of lipid phosphatases selectively dephosphorylate the 3 position of the inositol ring of phosphoinositide signaling molecules: the PTEN and the Myotubularin families. PTEN dephosphorylates PtdIns(3,4,5)P(3), acting in direct opposition to the Class I PI3K enzymes in the regulation of cell growth, proliferation and polarity and is an important tumor suppressor. Although there are several PTEN-related proteins encoded by the human genome, none of these appear to fulfill the same functions. In contrast, the Myotubularins dephosphorylate both PtdIns(3)P and PtdIns(3,5)P(2), making them antagonists of the Class II and Class III PI 3-kinases and regulators of membrane traffic. Both phosphatase groups were originally identified through their causal mutation in human disease. Mutations in specific myotubularins result in myotubular myopathy and Charcot-Marie-Tooth peripheral neuropathy; and loss of PTEN function through mutation and other mechanisms is evident in as many as a third of all human tumors. This chapter will discuss these two classes of phosphatases, covering what is known about their biochemistry, their functions at the cellular and whole body level and their influence on human health.
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Affiliation(s)
- Elizabeth M Davies
- Division of Cell Signalling and Immunology, Wellcome Trust Biocentre, College of Life Sciences, University of Dundee, Dow Street, DD1 5EH, Dundee, Scotland, United Kingdom,
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294
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Mellinghoff IK, Schultz N, Mischel PS, Cloughesy TF. Will kinase inhibitors make it as glioblastoma drugs? Curr Top Microbiol Immunol 2012; 355:135-69. [PMID: 22015553 PMCID: PMC3784987 DOI: 10.1007/82_2011_178] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Kinase inhibitors have emerged as effective cancer therapeutics in a variety of human cancers. Glioblastoma (GBM), the most common malignant brain tumor in adults, represents a compelling disease for kinase inhibitor therapy because the majority of these tumors harbor genetic alterations that result in aberrant activation of growth factor signaling pathways. Attempts to target the Ras-Phosphatidylinositol 3-kinase (PI3K)-mammalian Target of Rapamycin (mTOR) axis in GBM with first generation receptor tyrosine kinase (RTK) inhibitors and rapalogs have been disappointing. However, there is reason for renewed optimism given the now very detailed knowledge of the cancer genome in GBM and a wealth of novel compounds entering the clinic, including next generation RTK inhibitors, class I PI3K inhibitors, mTOR kinase inhibitors (TORKinibs), and dual PI3(K)/mTOR inhibitors. This chapter reviews common genetic alterations in growth factor signaling pathways in GBM, their validation as therapeutic targets in this disease, and strategies for future clinical development of kinase inhibitors for high grade glioma.
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Affiliation(s)
- Ingo K Mellinghoff
- Department and Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
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295
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Abstract
AbstractPTEN (phosphatase and tensin homologue deleted in chromosome 10) was first identified as a candidate tumour suppressor gene located on chromosome 10q23. It is considered as one of the most frequently mutated genes in human malignancies. Emerging evidence shows that the biological function of PTEN extends beyond its tumour suppressor activity. In the central nervous system PTEN is a crucial regulator of neuronal development, neuronal survival, axonal regeneration and synaptic plasticity. Furthermore, PTEN has been linked to the pathogenesis of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis. Recently increased attention has been focused on PTEN as a potential target for the treatment of brain injury and neurodegeneration. In this review we discuss the essential functions of PTEN in the central nervous system and its involvement in neurodegeneration.
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296
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Cesetti T, Fila T, Obernier K, Bengtson CP, Li Y, Mandl C, Hölzl-Wenig G, Ciccolini F. GABAA receptor signaling induces osmotic swelling and cell cycle activation of neonatal prominin+ precursors. Stem Cells 2011; 29:307-19. [PMID: 21732488 DOI: 10.1002/stem.573] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Signal-regulated changes in cell size affect cell division and survival and therefore are central to tissue morphogenesis and homeostasis. In this respect, GABA receptors (GABA(A)Rs) are of particular interest because allowing anions flow across the cell membrane modulates the osmolyte flux and the cell volume. Therefore, we have here investigated the hypothesis that GABA may regulate neural stem cell proliferation by inducing cell size changes. We found that, besides neuroblasts, also neural precursors in the neonatal murine subependymal zone sense GABA via GABA(A) Rs. However, unlike in neuroblasts, where it induced depolarization-mediated [Ca(2+)](i) increase, GABA(A) Rs activation in precursors caused hyperpolarization. This resulted in osmotic swelling and increased surface expression of epidermal growth factor receptors (EGFRs). Furthermore, activation of GABA(A) Rs signaling in vitro in the presence of EGF modified the expression of the cell cycle regulators, phosphatase and tensin homolog and cyclin D1, increasing the pool of cycling precursors without modifying cell cycle length. A similar effect was observed on treatment with diazepam. We also demonstrate that GABA and diazepam responsive precursors represent prominin(+) stem cells. Finally, we show that as in in vitro also in in vivo a short administration of diazepam promotes EGFR expression in prominin(+) stem cells causing activation and cell cycle entry. Thus, our data indicate that endogenous GABA is a part of a regulatory mechanism of size and cell cycle entry of neonatal stem cells. Our results also have potential implications for the therapeutic practices that involve exposure to GABA(A) Rs modulators during neurodevelopment.
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Affiliation(s)
- Tiziana Cesetti
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
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297
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Sakagami K, Chen B, Nusinowitz S, Wu H, Yang XJ. PTEN regulates retinal interneuron morphogenesis and synaptic layer formation. Mol Cell Neurosci 2011; 49:171-83. [PMID: 22155156 DOI: 10.1016/j.mcn.2011.11.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 11/21/2011] [Accepted: 11/26/2011] [Indexed: 11/15/2022] Open
Abstract
The lipid phosphatase PTEN is a critical negative regulator of extracellular signal-induced PI3K activities, yet the roles of PTEN in the neural retina remain poorly understood. Here, we investigate the function of PTEN during retinal development. Deletion of Pten at the onset of neurogenesis in retinal progenitors results in the reduction of retinal ganglion cells and rod photoreceptors, but increased Müller glial genesis. In addition, PTEN deficiency leads to elevated phosphorylation of Akt, especially in the developing inner plexiform layer, where high levels of PTEN are normally expressed. In Pten mutant retinas, various subtypes of amacrine cells show severe dendritic overgrowth, causing specific expansion of the inner plexiform layer. However, the outer plexiform layer remains relatively undisturbed in the Pten deficient retina. Physiological analysis detects reduced rod function and augmented oscillatory potentials originating from amacrine cells in Pten mutants. Furthermore, deleting Pten or elevating Akt activity in individual amacrine cells is sufficient to disrupt dendritic arborization, indicating that Pten activity is required cell autonomously to control neuronal morphology. Moreover, inhibiting endogenous Akt activity attenuates inner plexiform layer formation in vitro. Together, these findings demonstrate that suppression of PI3K/Akt signaling by PTEN is crucial for proper neuronal differentiation and normal retinal network formation.
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Affiliation(s)
- Kiyo Sakagami
- Jules Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
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298
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Paolella BR, Havrda MC, Mantani A, Wray CM, Zhang Z, Israel MA. p53 directly represses Id2 to inhibit the proliferation of neural progenitor cells. Stem Cells 2011; 29:1090-101. [PMID: 21608079 DOI: 10.1002/stem.660] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Neural progenitor cells (NPCs) have the capacity to proliferate and give rise to all major central nervous system cell types and represent a possible cell of origin in gliomagenesis. Deletion of the tumor suppressor gene Tp53 (p53) results in increased proliferation and self-renewal of NPCs and is a common genetic mutation found in glioma. We have identified inhibitor of DNA binding 2 (Id2) as a novel target gene directly repressed by p53 to maintain normal NPC proliferation. p53((-/-)) NPCs express elevated levels of Id2 and suppression of Id2 expression is sufficient to inhibit the increased proliferation and self-renewal which results from p53 loss. Elevated expression of Id2 in wild-type NPCs phenocopies the behavior of p53((-/-)) NPCs by enhancing NPC proliferation and self-renewal. Interestingly, p53 directly binds to a conserved site within the Id2 promoter to mediate these effects. Finally, we have identified elevated Id2 expression in glioma cell lines with mutated p53 and demonstrated that constitutive expression of Id2 plays a key role in the proliferation of glioma stem-like cells. These findings indicate that Id2 functions as a proproliferative gene that antagonizes p53-mediated cell cycle regulation in NPCs and may contribute to the malignant proliferation of glioma-derived tumor stem cells.
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Affiliation(s)
- Brenton R Paolella
- Norris Cotton Cancer Center, Dartmouth Medical School, Hanover, New Hampshire, USA.
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299
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Darido C, Georgy SR, Wilanowski T, Dworkin S, Auden A, Zhao Q, Rank G, Srivastava S, Finlay MJ, Papenfuss AT, Pandolfi PP, Pearson RB, Jane SM. Targeting of the tumor suppressor GRHL3 by a miR-21-dependent proto-oncogenic network results in PTEN loss and tumorigenesis. Cancer Cell 2011; 20:635-48. [PMID: 22094257 DOI: 10.1016/j.ccr.2011.10.014] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 09/02/2011] [Accepted: 10/13/2011] [Indexed: 01/17/2023]
Abstract
Despite its prevalence, the molecular basis of squamous cell carcinoma (SCC) remains poorly understood. Here, we identify the developmental transcription factor Grhl3 as a potent tumor suppressor of SCC in mice, and demonstrate that targeting of Grhl3 by a miR-21-dependent proto-oncogenic network underpins SCC in humans. Deletion of Grhl3 in adult epidermis evokes loss of expression of PTEN, a direct GRHL3 target, resulting in aggressive SCC induced by activation of PI3K/AKT/mTOR signaling. Restoration of Pten expression completely abrogates SCC formation. Reduced levels of GRHL3 and PTEN are evident in human skin, and head and neck SCC, associated with increased expression of miR-21, which targets both tumor suppressors. Our data define the GRHL3-PTEN axis as a critical tumor suppressor pathway in SCC.
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Affiliation(s)
- Charbel Darido
- Department of Medicine, Monash University Central Clinical School, Prahran, Victoria 3181, Australia
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300
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Sustained axon regeneration induced by co-deletion of PTEN and SOCS3. Nature 2011; 480:372-5. [PMID: 22056987 PMCID: PMC3240702 DOI: 10.1038/nature10594] [Citation(s) in RCA: 531] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 09/28/2011] [Indexed: 01/21/2023]
Abstract
A formidable challenge in neural repair in the adult central nervous system (CNS) is the long distances that regenerating axons often need to travel in order to reconnect with their targets. Thus, a sustained capacity for axon regeneration is critical for achieving functional restoration. Although deletion of either Phosphatase and tensin homolog (PTEN), a negative regulator of mammalian target of rapamycin (mTOR), or suppressor of cytokine signaling 3 (SOCS3), a negative regulator of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, in adult retinal ganglion cells (RGCs) individually promoted significant optic nerve regeneration, such regrowth tapered off around two weeks after the crush injury1,2. Remarkably, we now find that simultaneous deletion of both PTEN and SOCS3 enables robust and sustained axon regeneration. We further show that PTEN and SOCS3 regulate two independent pathways that act synergistically to promote enhanced axon regeneration. Gene expression analyses suggest that double deletion not only results in the induction of many growth-related genes, but also allows RGCs to maintain the expression of a repertoire of genes at the physiological level after injury. Our results reveal concurrent activation of mTOR and STAT3 pathways as a key for sustaining long-distance axon regeneration in adult CNS, a crucial step toward functional recovery.
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