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Heras-Sandoval D, Avila-Muñoz E, Arias C. The Phosphatidylinositol 3-Kinase/mTor Pathway as a Therapeutic Target for Brain Aging and Neurodegeneration. Pharmaceuticals (Basel) 2011. [PMCID: PMC4058660 DOI: 10.3390/ph4081070] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Many pathological conditions are associated with phosphatidylinositol 3-kinase (PI3K) dysfunction, providing an incentive for the study of the effects of PI3K modulation in different aspects of diabetes, cancer, and aging. The PI3K/AKT/mTOR pathway is a key transducer of brain metabolic and mitogenic signals involved in neuronal proliferation, differentiation, and survival. In several models of neurodegenerative diseases associated with aging, the PI3K/AKT pathway has been found to be dysregulated, suggesting that two or more initiating events may trigger disease formation in an age-related manner. The search for chemical compounds able to modulate the activity of the PI3K/AKT/mTOR pathway is emerging as a potential therapeutic strategy for the treatment and/or prevention of some metabolic defects associated with brain aging. In the current review, we summarize some of the critical actions of PI3K in brain function as well as the evidence of its involvement in aging and Alzheimer's disease.
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Affiliation(s)
| | | | - Clorinda Arias
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +52-55-56229215; Fax: +52-55-56229182
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52
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Babiarz JE, Hsu R, Melton C, Thomas M, Ullian EM, Blelloch R. A role for noncanonical microRNAs in the mammalian brain revealed by phenotypic differences in Dgcr8 versus Dicer1 knockouts and small RNA sequencing. RNA (NEW YORK, N.Y.) 2011; 17:1489-501. [PMID: 21712401 PMCID: PMC3153973 DOI: 10.1261/rna.2442211] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 05/11/2011] [Indexed: 05/24/2023]
Abstract
Noncanonical microRNAs (miRNAs) and endogenous small interfering RNAs (endo-siRNAs) are distinct subclasses of small RNAs that bypass the DGCR8/DROSHA Microprocessor but still require DICER1 for their biogenesis. What role, if any, they have in mammals remains unknown. To identify potential functional properties for these subclasses, we compared the phenotypes resulting from conditional deletion of Dgcr8 versus Dicer1 in post-mitotic neurons. The loss of Dicer1 resulted in an earlier lethality, more severe structural abnormalities, and increased apoptosis relative to that from Dgcr8 loss. Deep sequencing of small RNAs from the hippocampus and cortex of the conditional knockouts and control littermates identified multiple noncanonical microRNAs that were expressed at high levels in the brain relative to other tissues, including mirtrons and H/ACA snoRNA-derived small RNAs. In contrast, we found no evidence for endo-siRNAs in the brain. Taken together, our findings provide evidence for a diverse population of highly expressed noncanonical miRNAs that together are likely to play important functional roles in post-mitotic neurons.
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Affiliation(s)
- Joshua E. Babiarz
- The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Center for Reproductive Sciences, University of California, San Francisco, San Francisco, California 94143, USA
- Department of Urology, University of California, San Francisco, San Francisco, California 94143, USA
| | - Ruby Hsu
- Department of Ophthalmology and Physiology, University of California, San Francisco, San Francisco, California 94143, USA
| | - Collin Melton
- The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Center for Reproductive Sciences, University of California, San Francisco, San Francisco, California 94143, USA
- Department of Urology, University of California, San Francisco, San Francisco, California 94143, USA
- Program in Biomedical Sciences, University of California, San Francisco, San Francisco, California 94143, USA
| | - Molly Thomas
- Program in Biomedical Sciences, University of California, San Francisco, San Francisco, California 94143, USA
| | - Erik M. Ullian
- Department of Ophthalmology and Physiology, University of California, San Francisco, San Francisco, California 94143, USA
| | - Robert Blelloch
- The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Center for Reproductive Sciences, University of California, San Francisco, San Francisco, California 94143, USA
- Department of Urology, University of California, San Francisco, San Francisco, California 94143, USA
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53
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Phosphoinositide-3-kinase activation controls synaptogenesis and spinogenesis in hippocampal neurons. J Neurosci 2011; 31:2721-33. [PMID: 21414895 DOI: 10.1523/jneurosci.4477-10.2011] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The possibility of changing the number of synapses may be an important asset in the treatment of neurological diseases. In this context, the synaptogenic role of the phosphoinositide-3-kinase (PI3K) signaling cascade has been previously demonstrated in Drosophila. This study shows that treatment with a PI3K-activating transduction peptide is able to promote synaptogenesis and spinogenesis in primary cultures of rat hippocampal neurons, as well as in CA1 hippocampal neurons in vivo. In culture, the peptide increases synapse density independently of cell density, culture age, dendritic complexity, or synapse type. The induced synapses also increase neurotransmitter release from cultured neurons. The synaptogenic signaling pathway includes PI3K-Akt. Furthermore, the treatment is effective on adult neurons, where it induces spinogenesis and enhances the cognitive behavior of treated animals in a fear-conditioning assay. These findings demonstrate that functional synaptogenesis can be induced in mature mammalian brains through PI3K activation.
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54
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Liu Z, Gao W, Wang Y, Zhang W, Liu H, Li Z. Neuregulin-1β regulates outgrowth of neurites and migration of neurofilament 200 neurons from dorsal root ganglial explants in vitro. Peptides 2011; 32:1244-8. [PMID: 21515322 DOI: 10.1016/j.peptides.2011.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2011] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 01/05/2023]
Abstract
Neuregulin-1β (NRG-1β) signaling has multiple functions in neurons. To assess NRG-1β on neurite outgrowth and neuronal migration in vitro, organotypic dorsal root ganglion (DRG) neuronal culture model was established. Neurite outgrowth and neuronal migration were evaluated using this culture model in the presence (5nmol/L, 10nmol/L, 20nmol/L) or absence of NRG-1β. Neurofilament 200 (NF-200)-immunoreactive (IR) neurons were determined as the migrating neurons. The number of nerve fiber bundles extended from DRG explant increased significantly in the presence of NRG-1β (5nmol/L, 23.0±2.2, P<0.05; 10nmol/L, 27.0±2.7, P<0.001; 20nmol/L, 30.8±3.7, P<0.001) as compared with that in the absence of NRG-1β (19.0±2.2). The number of neurons migrating from DRG explants increased significantly in the presence of NRG-1β (5nmol/L, 39.6±5.0, P<0.05; 10nmol/L, 54.6±6.7, P<0.001; 20nmol/L, 62.2±5.7, P<0.001) as compared with that in the absence of NRG-1β (31.6±4.0). Moreover, the increase of the number of nerve fiber bundles and the number of migrating NF-200-IR neurons was dose-dependent for NRG-1β addition. The data in this study imply that NRG-1β promotes neurite outgrowth and neuronal migration from DRG explants in vitro.
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Affiliation(s)
- Zhen Liu
- Department of Anatomy, Shandong University School of Medicine, 44 Wenhua Xi Road, Jinan, Shandong Province 250012, China
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55
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Salcedo-Tello P, Ortiz-Matamoros A, Arias C. GSK3 Function in the Brain during Development, Neuronal Plasticity, and Neurodegeneration. Int J Alzheimers Dis 2011; 2011:189728. [PMID: 21660241 PMCID: PMC3109514 DOI: 10.4061/2011/189728] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 03/07/2011] [Indexed: 02/06/2023] Open
Abstract
GSK3 has diverse functions, including an important role in brain pathology. In this paper, we address the primary functions of GSK3 in development and neuroplasticity, which appear to be interrelated and to mediate age-associated neurological diseases. Specifically, GSK3 plays a pivotal role in controlling neuronal progenitor proliferation and establishment of neuronal polarity during development, and the upstream and downstream signals modulating neuronal GSK3 function affect cytoskeletal reorganization and neuroplasticity throughout the lifespan. Modulation of GSK3 in brain areas subserving cognitive function has become a major focus for treating neuropsychiatric and neurodegenerative diseases. As a crucial node that mediates a variety of neuronal processes, GSK3 is proposed to be a therapeutic target for restoration of synaptic functioning and cognition, particularly in Alzheimer's disease.
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Affiliation(s)
- Pamela Salcedo-Tello
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, AP 70-228, 04510 Ciudad de México, Mexico
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56
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Pretreatment with phosphatase and tensin homolog deleted on chromosome 10 (PTEN) inhibitor SF1670 augments the efficacy of granulocyte transfusion in a clinically relevant mouse model. Blood 2011; 117:6702-13. [PMID: 21521784 DOI: 10.1182/blood-2010-09-309864] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The clinical outcome of granulocyte transfusion therapy is often hampered by short ex vivo shelf life, inefficiency of recruitment to sites of inflammation, and poor pathogen-killing capability of transplanted neutrophils. Here, using a recently developed mouse granulocyte transfusion model, we revealed that the efficacy of granulocyte transfusion can be significantly increased by elevating intracellular phosphatidylinositol (3,4,5)-trisphosphate signaling with a specific phosphatase and tensin homolog deleted on chromosome 10 (PTEN) inhibitor SF1670. Neutrophils treated with SF1670 were much sensitive to chemoattractant stimulation. Neutrophil functions, such as phagocytosis, oxidative burst, polarization, and chemotaxis, were augmented after SF1670 treatment. The recruitment of SF1670-pretreated transfused neutrophils to the inflamed peritoneal cavity and lungs was significantly elevated. In addition, transfusion with SF1670-treated neutrophils led to augmented bacteria-killing capability (decreased bacterial burden) in neutropenic recipient mice in both peritonitis and bacterial pneumonia. Consequently, this alleviated the severity of and decreased the mortality of neutropenia-related pneumonia. Together, these observations demonstrate that the innate immune responses can be enhanced and the severity of neutropenia-related infection can be alleviated by augmenting phosphatidylinositol (3,4,5)-trisphosphate in transfused neutrophils with PTEN inhibitor SF1670, providing a therapeutic strategy for improving the efficacy of granulocyte transfusion.
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57
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Tolias KF, Duman JG, Um K. Control of synapse development and plasticity by Rho GTPase regulatory proteins. Prog Neurobiol 2011; 94:133-48. [PMID: 21530608 DOI: 10.1016/j.pneurobio.2011.04.011] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 04/13/2011] [Accepted: 04/15/2011] [Indexed: 12/21/2022]
Abstract
Synapses are specialized cell-cell contacts that mediate communication between neurons. Most excitatory synapses in the brain are housed on dendritic spines, small actin-rich protrusions extending from dendrites. During development and in response to environmental stimuli, spines undergo marked changes in shape and number thought to underlie processes like learning and memory. Improper spine development, in contrast, likely impedes information processing in the brain, since spine abnormalities are associated with numerous brain disorders. Elucidating the mechanisms that regulate the formation and plasticity of spines and their resident synapses is therefore crucial to our understanding of cognition and disease. Rho-family GTPases, key regulators of the actin cytoskeleton, play essential roles in orchestrating the development and remodeling of spines and synapses. Precise spatio-temporal regulation of Rho GTPase activity is critical for their function, since aberrant Rho GTPase signaling can cause spine and synapse defects as well as cognitive impairments. Rho GTPases are activated by guanine nucleotide exchange factors (GEFs) and inhibited by GTPase-activating proteins (GAPs). We propose that Rho-family GEFs and GAPs provide the spatiotemporal regulation and signaling specificity necessary for proper Rho GTPase function based on the following features they possess: (i) existence of multiple GEFs and GAPs per Rho GTPase, (ii) developmentally regulated expression, (iii) discrete localization, (iv) ability to bind to and organize specific signaling networks, and (v) tightly regulated activity, perhaps involving GEF/GAP interactions. Recent studies describe several Rho-family GEFs and GAPs that uniquely contribute to spinogenesis and synaptogenesis. Here, we highlight several of these proteins and discuss how they occupy distinct biochemical niches critical for synaptic development.
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Affiliation(s)
- Kimberley F Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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58
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Insulin receptor substrate-1 and -2 mediate resistance to glucose-induced caspase-3 activation in human neuroblastoma cells. Biochim Biophys Acta Mol Basis Dis 2011; 1812:573-80. [PMID: 21354306 DOI: 10.1016/j.bbadis.2011.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 02/08/2011] [Accepted: 02/15/2011] [Indexed: 12/19/2022]
Abstract
Hyperglycemia in patients with type 2 diabetes causes multiple neuronal complications, e.g., diabetic polyneuropathy, cognitive decline, and embryonic neural crest defects due to increased apoptosis. Possible mechanisms of neuronal response to increased glucose burden are still a matter of debate. Insulin and insulin-like growth factor-1 (IGF-1) receptor signaling inhibits glucose-induced caspase-3 activation and apoptotic cell death. The insulin receptor substrates (IRS) are intracellular adapter proteins mediating insulin's and IGF-1's intracellular effects. Even though all IRS proteins have similar function and structure, recent data suggest different actions of IRS-1 and IRS-2 in mediating their anti-apoptotic effects in glucose neurotoxicity. We therefore investigated the role of IRS-1/-2 in glucose-induced caspase-3 activation using human neuroblastoma cells. Overexpression of IRS-1 or IRS-2 caused complete resistance to glucose-induced caspase-3 cleavage. Inhibition of PI3-kinase reversed this protective effect of IRS-1 or IRS-2. However, MAP-kinases inhibition had only minor impact. IRS overexpression increased MnSOD abundance as well as BAD phosphorylation while Bim and BAX levels remained unchanged. Since Akt promotes cell survival at least partially via phosphorylation and inhibition of downstream forkhead box-O (FoxO) transcription factors, we generated neuroblastoma cells stably overexpressing a dominant negative mutant of FoxO1 mimicking activation of the insulin/IGF-1 pathway on FoxO-mediated transcription. Using these cells we showed that FoxO1 is not involved in neuronal protection mediated by increased IRS-1/-2 expression. Thus, overexpression of both IRS-1 and IRS-2 induces complete resistance to glucose-induced caspase-3 activation via PI3-kinase mediated BAD phosphorylation and MnSOD expression independent of FoxO1.
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59
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Takeda S, Sato N, Rakugi H, Morishita R. Molecular mechanisms linking diabetes mellitus and Alzheimer disease: beta-amyloid peptide, insulin signaling, and neuronal function. MOLECULAR BIOSYSTEMS 2011; 7:1822-7. [DOI: 10.1039/c0mb00302f] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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60
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Liu T, Jin H, Sun QR, Xu JH, Hu HT. Neuroprotective effects of emodin in rat cortical neurons against beta-amyloid-induced neurotoxicity. Brain Res 2010; 1347:149-60. [PMID: 20573598 DOI: 10.1016/j.brainres.2010.05.079] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/24/2010] [Accepted: 05/25/2010] [Indexed: 12/21/2022]
Abstract
Accumulation of beta-amyloid protein (Abeta) in the brain plays an important role in the pathogenesis of Alzheimer's disease (AD). In this study, the neuroprotective effect of emodin extracted from the traditional Chinese medicinal herb Polygonum cuspidatum Sieb. et Zucc against Abeta(25-35)-induced cell death in cultured cortical neurons was investigated. We found that pre-treatment with emodin prevented the cultured cortical neurons from beta-amyloid-induced toxicity. The preventive effect of emodin was blocked by pre-treatment with a phosphatidylinositol-3-kinase (PI3K) pathway inhibitor LY294002 or an estrogen receptor (ER) specific antagonist ICI182780, but not by pre-treatment with an extracellular signal-related kinases (ERK) inhibitor U0126. Furthermore, we found that emodin exposure induced the activation of the Akt serine/threonine kinase and increased the level of Bcl-2 expression. Moreover, the application of emodin for 24h was able to induce the activation of Abeta(25-35)-suppressed Akt and decrease the activation of the Jun-N-terminal kinases (JNK), but not of ERK. Interestingly, the up-regulation of Akt and Bcl-2 did not occur in the presence of LY294002 or ICI182780, suggesting that emodin-up-regulated Bcl-2 is mediated via the ER and PI3K/Akt pathway. Taken together, our results suggest that emodin is an effective neuroprotective drug and is a viable candidate for treating AD.
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Affiliation(s)
- Tao Liu
- Department of Human Anatomy and Histology & Embryology, Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
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61
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Zoubaa S, Konrad R, Piontek G, Schlegel J. Inhibition of NGF-induced neurite outgrowth of rat pheochromocytoma cells (PC12) following administration of dioxyamphetamine. Neurosci Lett 2010; 476:113-8. [PMID: 20138971 DOI: 10.1016/j.neulet.2010.01.070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 01/12/2010] [Accepted: 01/28/2010] [Indexed: 10/19/2022]
Abstract
Amphetamine analogs are known to induce not only neurotoxicity at serotonergic axon terminals but also neocortical neuronal degeneration. However, a much less studied aspect involves the impact of amphetamine exposure on neuronal development. The present study investigated whether pretreatment of PC12 cells with dioxyamphetamine (DA) alters differentiation of PC12 cells by NGF and, if so, which components of the Ras/Raf/MEK/ERK pathway known to be involved in the differentiation response to NGF are particularly affected. Though exposure of PC12 cells to DA 1h prior to NGF treatment resulted in apopotosis, several PC12 cells survived. However, neurite outgrowth of these NGF-responsive cells was repressed. Immunoblots of whole cell extracts revealed a strong induction rather than inhibition of ERK phosphorylation up to 48h after DA/NGF treatment. Our results indicate that NGF-mediated neurite outgrowth was inhibited by pretreatment with DA, and this blockage of NGF-induced neuritogenesis was not due to an inhibition of ERK phosphorylation.
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Affiliation(s)
- S Zoubaa
- Institute of Pathology, Division of Neuropathology, Technical University, Ismaninger Strasse 22, D-81675 Munich, Germany.
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62
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Gilardino A, Farcito S, Zamburlin P, Audisio C, Lovisolo D. Specificity of the second messenger pathways involved in basic fibroblast growth factor-induced survival and neurite growth in chick ciliary ganglion neurons. J Neurosci Res 2010; 87:2951-62. [PMID: 19405103 DOI: 10.1002/jnr.22116] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Basic fibroblast growth factor (bFGF) exerts multiple neurotrophic actions on cultured neurons from the ciliary ganglion of chick embryo, among them promotion of neuronal survival and of neurite outgrowth. To understand the specificity of the signal transduction cascades involved in the control of these processes, we used pharmacological inhibitors of the three main effectors known to act downstream of the bFGF receptor (FGFR): phospholipase Cgamma (PLCgamma), mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3-K). Neuronal survival was assessed at 24 and 48 hr; neurite growth was analyzed both on dissociated neurons and on explants of whole ganglia. Our data show that only the PI3-K pathway is involved in the survival-promoting effect of bFGF; on the other hand, all three effectors converge on the enhancement of neurite outgrowth, both on isolated neurons and in whole ganglia.
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63
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Kitazawa H, Numakawa T, Adachi N, Kumamaru E, Tuerxun T, Kudo M, Kunugi H. Cyclophosphamide promotes cell survival via activation of intracellular signaling in cultured cortical neurons. Neurosci Lett 2010; 470:139-44. [PMID: 20056130 DOI: 10.1016/j.neulet.2009.12.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Revised: 12/16/2009] [Accepted: 12/29/2009] [Indexed: 12/12/2022]
Abstract
Cyclophosphamide (CP) has been used as an antitumour agent or immunosuppressant clinically, though the potential biological role of CP in the central nervous system (CNS) has not been clarified. In the present study, we found that pretreatment with CP prevented neuronal cell death caused by serum deprivation in cultured cortical neurons. Interestingly, CP stimulated activation of PI3K (phosphatidylinositol 3 kinase) and MAPK/ERK (mitogen-activated protein kinase/extracellular signal-regulated kinase) pathways, which are known as survival-promoting intracellular signalings. Furthermore, CP increased the expression of Bcl2, an anti-apoptotic factor. In the presence of inhibitors for PI3K or MAPK/ERK pathways, the CP-dependent neuronal survival and Bcl-2 up-regulation were both abolished. Importantly, significant increase in BDNF (brain-derived neurotrophic factor) expression was induced by CP application, implying that BDNF up-regulation is involved in the CP effect. We propose that CP has a protective effect on CNS neurons via the activation of intracellular signalings, and up-regulation of Bcl2 and BDNF.
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Affiliation(s)
- Hiromi Kitazawa
- Department of Pathology, Tokyo Medical University, Tokyo 160-8401, Japan
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64
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SA4503, a sigma-1 receptor agonist, prevents cultured cortical neurons from oxidative stress-induced cell death via suppression of MAPK pathway activation and glutamate receptor expression. Neurosci Lett 2010; 469:303-8. [DOI: 10.1016/j.neulet.2009.12.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 11/19/2009] [Accepted: 12/09/2009] [Indexed: 11/23/2022]
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65
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Cardoso S, Santos R, Correia S, Carvalho C, Zhu X, Lee HG, Casadesus G, Smith MA, Perry G, Moreira PI. Insulin and Insulin-Sensitizing Drugs in Neurodegeneration: Mitochondria as Therapeutic Targets. Pharmaceuticals (Basel) 2009; 2:250-286. [PMID: 27713238 PMCID: PMC3978547 DOI: 10.3390/ph2030250] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 12/21/2009] [Accepted: 12/22/2009] [Indexed: 12/13/2022] Open
Abstract
Insulin, besides its glucose lowering effects, is involved in the modulation of lifespan, aging and memory and learning processes. As the population ages, neurodegenerative disorders become epidemic and a connection between insulin signaling dysregulation, cognitive decline and dementia has been established. Mitochondria are intracellular organelles that despite playing a critical role in cellular metabolism are also one of the major sources of reactive oxygen species. Mitochondrial dysfunction, oxidative stress and neuroinflammation, hallmarks of neurodegeneration, can result from impaired insulin signaling. Insulin-sensitizing drugs such as the thiazolidinediones are a new class of synthetic compounds that potentiate insulin action in the target tissues and act as specific agonists of the peroxisome proliferator-activated receptor gamma (PPAR-γ). Recently, several PPAR agonists have been proposed as novel and possible therapeutic agents for neurodegenerative disorders. Indeed, the literature shows that these agents are able to protect against mitochondrial dysfunction, oxidative damage, inflammation and apoptosis. This review discusses the role of mitochondria and insulin signaling in normal brain function and in neurodegeneration. Furthermore, the potential protective role of insulin and insulin sensitizers in Alzheimer´s, Parkinson´s and Huntington´s diseases and amyotrophic lateral sclerosis will be also discussed.
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Affiliation(s)
- Susana Cardoso
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Renato Santos
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Sonia Correia
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Cristina Carvalho
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Xiongwei Zhu
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Hyoung-Gon Lee
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Gemma Casadesus
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mark A Smith
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - George Perry
- College of Sciences, The University of Texas at San Antonio, TX 78249, USA
| | - Paula I Moreira
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal.
- Institute of Physiology, Faculty of Medicine, University of Coimbra, 3000-354 Coimbra, Portugal.
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66
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Glucocorticoid attenuates brain-derived neurotrophic factor-dependent upregulation of glutamate receptors via the suppression of microRNA-132 expression. Neuroscience 2009; 165:1301-11. [PMID: 19958814 DOI: 10.1016/j.neuroscience.2009.11.057] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 11/02/2009] [Accepted: 11/23/2009] [Indexed: 11/21/2022]
Abstract
Brain-specific microRNAs (miRs) may be involved in synaptic plasticity through the control of target mRNA translation. Brain-derived neurotrophic factor (BDNF) also contributes to the regulation of synaptic function. However, the possible involvement of miRs in BDNF-regulated synaptic function is poorly understood. Importantly, an increase in glucocorticoid levels and the downregulation of BDNF are supposed to be involved in the pathophysiology of depressive disorders. Previously, we reported that glucocorticoid exposure inhibited BDNF-regulated synaptic function via weakening mitogen-activated protein kinase/extracellular signal-regulated kinase1/2 (MAPK/ERK) and/or phospholipase C-gamma (PLC-gamma) intracellular signaling in cultured neurons [Kumamaru et al (2008) Mol Endocrinol 22:546-558; Numakawa et al (2009) Proc Natl Acad Sci U S A 106:647-652]. Therefore, in this study, we investigate the possible influence of glucocorticoid on BDNF/miRs-stimulated biological responses in cultured cortical neurons. Significant upregulation of miR-132 was caused by BDNF, although miR-9, -124, -128a, -128b, -134, -138, and -16 were intact. Transfection of exogenous ds-miR-132 induced marked upregulation of glutamate receptors (NR2A, NR2B, and GluR1), suggesting that miR-132 has a positive effect on the increase in postsynaptic proteins levels. Consistently, transfection of antisense RNA to inhibit miR-132 function decreased the BDNF-dependent increase in the expression of postsynaptic proteins. U0126, an inhibitor of the MAPK/ERK pathway, suppressed the BDNF-increased miR-132, suggesting that BDNF upregulates miR-132 via the MAPK/ERK1/2 pathway. Interestingly, pretreatment with glucocorticoid (dexamethasone, DEX) reduced BDNF-increased ERK1/2 activation, miR-132 expression, and postsynaptic proteins. We demonstrate that the exposure of neurons to an excess glucocorticoid results in a decrease in the BDNF-dependent neuronal function via suppressing miR-132 expression.
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67
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Zhou Z, Peng X, Insolera R, Fink DJ, Mata M. Interleukin-10 provides direct trophic support to neurons. J Neurochem 2009; 110:1617-27. [PMID: 19575707 DOI: 10.1111/j.1471-4159.2009.06263.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Interleukin (IL)-10, a prototypical anti-inflammatory cytokine, has been shown to provide beneficial effects in neuronal injury in vivo but the full range of actions has not been established. In order to understand the neuronal mechanisms underlying IL-10-mediated neuroprotection, we examined the effect of IL-10 on primary neurons in culture. We found that IL-10 exerted a direct trophic influence on spinal cord neurons, and that activation of the neuronal IL-10 receptor provided trophic support and survival cues to overcome the neurotoxic effects of glutamate in vitro. IL-10 treatment resulted in activation of janus-associated kinases/signal transducers and transcription factors and phosphatidylinositol 3-kinase-AKT pathways in neurons to enhance expression of Bcl-2 and Bcl-x(L); under stress conditions IL-10 blocks cytochrome c release and caspase cleavage. IL-10 activation of the canonical nuclear factor kappaB pathway enhanced translocation of p50 and p65 and enhanced their binding to kappaB DNA sequences, with p50 playing a more prominent role in neuronal survival. These data indicate that in addition to known anti-inflammatory effects through astroglia in other inflammatory cells, IL-10 has direct neuronal effects with important implications for development and neuroprotection.
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Affiliation(s)
- Zhigang Zhou
- Department of Neurology, University of Michigan and Ann Arbor VA Healthcare System, Ann Arbor, Michigan, USA
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68
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Mukuno H, Nakamura M, Kanamori A, Nagai A, Negi A, Seigel G. Unoprostone isopropyl rescues retinal progenitor cells from apoptosisin vitro. Curr Eye Res 2009; 29:457-64. [PMID: 15764090 DOI: 10.1080/02713680490889465] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE Unoprostone isopropyl is an ocular hypotensive that was originally produced as a prostaglandin F2alpha analogue and is eventually recognized as a synthetic docosanoid. The compound is recently suggested to have potent neuroprotective ability in the retina. The purpose of this study is to test whether and how the biologically active metabolites of unoprostone isopropyl rescue retinal neuro-glial progenitor cells from apoptosis. METHODS R28 cells were deprived of serum for 24 hr with or without varying concentrations of unoprostone metabolite M1 or M2 or vehicle in the presence or absence of specific inhibitors against several types of signal transduction proteins. Immunocytochemistry against activated caspase-3 with Hoechst nuclear staining was performed. RESULTS Up to 15%of R28 cells became pyknotic and activated caspase-3 immunoreactive after 24-hr serum withdrawal. M1, but not M2, significantly reduced apoptotic cells in a dose-dependent fashion with a maximal effect at 100 microM (p < .0001). LY294002, the phosphatidylinositol 3-OH kinase (PI3K) inhibitor, and KT5823, the protein kinase G (PKG) inhibitor, reversed the antiapoptotic effect of M1. CONCLUSIONS The unoprostone metabolite M1 protects retinal neuro-glial progenitor R28 cells from apoptosis induced by serum deprivation via the PI3K and PKG pathways.
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Affiliation(s)
- Hirokazu Mukuno
- Department of Organ Therapeutics, Division of Ophthalmology, Kobe University Graduate School of Medicine, Chuo-Ku, Kobe, Japan
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69
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Bonnici B, Kapfhammer JP. Modulators of signal transduction pathways can promote axonal regeneration in entorhino-hippocampal slice cultures. Eur J Pharmacol 2009; 612:35-40. [PMID: 19375417 DOI: 10.1016/j.ejphar.2009.04.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 03/24/2009] [Accepted: 04/07/2009] [Indexed: 10/20/2022]
Abstract
Axonal regeneration after lesions is usually not possible in the adult central nervous system but can occur in the embryonic and young postnatal nervous system. In this study we used the model system of mouse entorhino-hippocampal slice cultures to assess the potential of pharmacological treatments with compounds targeting signal transduction pathways to promote growth of entorhinal fibers after mechanical lesions across the lesion site to their target region in the dentate gyrus. Compounds acting on the cyclic AMP-system, protein kinase C and G-proteins have been shown before to be able to promote regeneration. In this study we have confirmed the potential of drugs affecting these systems to promote axonal regeneration in the central nervous system. In addition we have found that inhibition of the phosphoinositide 3-kinase pathway and of the inositol triphosphate receptor also promoted axonal growth across the lesion site and are thus potential novel drug targets for promoting axonal regeneration after central nervous system lesions. Our findings demonstrate that slice culture models can be used to evaluate compounds for their potential to promote axonal regeneration and that the pharmacological modulation of signal transduction pathways is a promising approach for promoting axonal repair.
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Affiliation(s)
- Brenda Bonnici
- Anatomical Institute, Department of Biomedicine Basel, University of Basel, 4056 Basel, Switzerland
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70
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Regulation of microtubule nucleation from membranes by complexes of membrane-bound γ-tubulin with Fyn kinase and phosphoinositide 3-kinase. Biochem J 2008; 416:421-30. [DOI: 10.1042/bj20080909] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The molecular mechanisms controlling microtubule formation in cells with non-centrosomal microtubular arrays are not yet fully understood. The key component of microtubule nucleation is γ-tubulin. Although previous results suggested that tyrosine kinases might serve as regulators of γ-tubulin function, their exact roles remain enigmatic. In the present study, we show that a pool of γ-tubulin associates with detergent-resistant membranes in differentiating P19 embryonal carcinoma cells, which exhibit elevated expression of the Src family kinase Fyn (protein tyrosine kinase p59Fyn). Microtubule-assembly assays demonstrated that membrane-associated γ-tubulin complexes are capable of initiating the formation of microtubules. Pretreatment of the cells with Src family kinase inhibitors or wortmannin blocked the nucleation activity of the γ-tubulin complexes. Immunoprecipitation experiments revealed that membrane-associated γ-tubulin forms complexes with Fyn and PI3K (phosphoinositide 3-kinase). Furthermore, in vitro kinase assays showed that p85α (regulatory p85α subunit of PI3K) serves as a Fyn substrate. Direct interaction of γ-tubulin with the C-terminal Src homology 2 domain of p85α was determined by pull-down experiments and immunoprecipitation experiments with cells expressing truncated forms of p85α. The combined results suggest that Fyn and PI3K might take part in the modulation of membrane-associated γ-tubulin activities.
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71
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Arboleda G, Morales LC, Benítez B, Arboleda H. Regulation of ceramide-induced neuronal death: cell metabolism meets neurodegeneration. ACTA ACUST UNITED AC 2008; 59:333-46. [PMID: 18996148 DOI: 10.1016/j.brainresrev.2008.10.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 10/09/2008] [Accepted: 10/13/2008] [Indexed: 12/14/2022]
Abstract
The present review explores the role of ceramides in neuronal apoptosis, as well as the recent discovery of the signaling pathways involved in this process placing particular emphasis on the correlation between cellular metabolism and neuronal death. Endogenous levels of ceramides are increased following various pro-apoptotic stimuli which have been identified as potential causes of chronic and acute neurodegenerative diseases. Ceramides induce changes in multiple enzymes and cell signaling components. The early inhibition of the neuronal survival pathway regulated by phosphatidil-inositol-3-kinase/protein kinase B or AKT mediated by ceramide may be a relevant early event in the decision of neuronal survival/death. It may perturb several molecular and metabolic functions. In particular it might decrease glycolysis through rapid modulation of hexokinase activity. This would in turn generate limited amounts of mitochondrial substrates leading to mitochondrial dysfunction and neuronal apoptosis. Subtle and early metabolic alterations caused by inhibition of the PI3K/AKT pathway mediated by ceramide may potentially work with genes associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Together they may be determinant steps in downstream events leading to neuronal apoptosis. Therefore, reinforcement of the PI3K/AKT pathway could constitute an important neuroprotective strategy.
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Affiliation(s)
- Gonzalo Arboleda
- Grupo de Neurociencias, Departamento de Patología, Facultad de Medicina, Universidad Nacional de Colombia, Bogotá, Colombia.
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72
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Sui L, Wang J, Li BM. Role of the phosphoinositide 3-kinase-Akt-mammalian target of the rapamycin signaling pathway in long-term potentiation and trace fear conditioning memory in rat medial prefrontal cortex. Learn Mem 2008; 15:762-76. [DOI: 10.1101/lm.1067808] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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73
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Krivosheya D, Tapia L, Levinson JN, Huang K, Kang Y, Hines R, Ting AK, Craig AM, Mei L, Bamji SX, El-Husseini A. ErbB4-neuregulin signaling modulates synapse development and dendritic arborization through distinct mechanisms. J Biol Chem 2008; 283:32944-56. [PMID: 18819924 DOI: 10.1074/jbc.m800073200] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Perturbations in neuregulin-1 (NRG1)/ErbB4 function have been associated with schizophrenia. Affected patients exhibit altered levels of these proteins and display hypofunction of glutamatergic synapses as well as altered neuronal circuitry. However, the role of NRG1/ErbB4 in regulating synapse maturation and neuronal process formation has not been extensively examined. Here we demonstrate that ErbB4 is expressed in inhibitory interneurons at both excitatory and inhibitory postsynaptic sites. Overexpression of ErbB4 postsynaptically enhances size but not number of presynaptic inputs. Conversely, knockdown of ErbB4 using shRNA decreases the size of presynaptic inputs, demonstrating a specific role for endogenous ErbB4 in synapse maturation. Using ErbB4 mutant constructs, we demonstrate that ErbB4-mediated synapse maturation requires its extracellular domain, whereas its tyrosine kinase activity is dispensable for this process. We also demonstrate that depletion of ErbB4 decreases the number of primary neurites and that stimulation of ErbB4 using a soluble form of NRG1 results in exuberant dendritic arborization through activation of the tyrosine kinase domain of ErbB4 and the phosphoinositide 3-kinase pathway. These findings demonstrate that NRG1/ErbB4 signaling differentially regulates synapse maturation and dendritic morphology via two distinct mechanisms involving trans-synaptic signaling and tyrosine kinase activity, respectively.
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Affiliation(s)
- Daria Krivosheya
- Department of Psychiatry, the Brain Research Center, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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74
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McIntyre RS, Vagic D, Swartz SA, Soczynska JK, Woldeyohannes HO, Voruganti LP, Konarski JZ. Insulin, insulin-like growth factors and incretins: neural homeostatic regulators and treatment opportunities. CNS Drugs 2008; 22:443-53. [PMID: 18484789 DOI: 10.2165/00023210-200822060-00001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mood disorders may be conceptualized as progressive neurodegenerative disorders associated with cognitive decline. Novel treatments capable of preserving and/or enhancing cognitive function represent an area of priority for research in the future. Insulin, insulin-like growth factor (IGF)-1 and incretins may play a critical role in both physiological and pathophysiological processes of the CNS. An emerging paradigm regarding the pathophysiology of mood disorders posits that alterations in biological networks that mediate stress compromise optimal neuronal and glial function. A growing body of evidence indicates that central administration of insulin may enhance cognitive function in both healthy and cognitively impaired individuals. The neuroactive peptides, insulin, IGF-1 and incretins, or agents that facilitate their central effects (e.g. insulin-sensitizing agents), may constitute novel and possibly disease-modifying neurocognitive treatments.
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Affiliation(s)
- Roger S McIntyre
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
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75
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Dwivedi Y, Rizavi HS, Teppen T, Zhang H, Mondal A, Roberts RC, Conley RR, Pandey GN. Lower phosphoinositide 3-kinase (PI 3-kinase) activity and differential expression levels of selective catalytic and regulatory PI 3-kinase subunit isoforms in prefrontal cortex and hippocampus of suicide subjects. Neuropsychopharmacology 2008; 33:2324-40. [PMID: 18075493 DOI: 10.1038/sj.npp.1301641] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phosphoinositide 3 (PI 3)-kinase is one of the key signaling enzymes that participates in a myriad of physiological functions in brain and is utilized by neurotrophins to mediate neuronal plasticity, cell survival, and inhibition of apoptosis for several neuronal subtypes. Our recent demonstration that expression of neurotrophic factors and activation of the receptor tyrosine kinase B are significantly altered in postmortem brain of suicide subjects led us to examine whether suicide brain is associated with alterations in PI 3-kinase signaling. In prefrontal cortex (PFC), hippocampus, and cerebellum of suicide (n=28) and nonpsychiatric control (n=21) subjects we examined catalytic activation of PI 3-kinase, and mRNA and protein levels of regulatory (p85alpha, p85beta) and catalytic (p110alpha, p110beta) subunits of PI 3-kinase. It was observed that the catalytic activity of PI 3-kinase was significantly reduced in PFC and hippocampus of suicide subjects compared with nonpsychiatric control subjects. Competitive PCR analysis revealed significantly reduced mRNA expression of p85beta and p110alpha and increased expression of p85alpha subunit isoforms in PFC and hippocampus of suicide subjects. Alterations in these catalytic and regulatory subunits were accompanied by changes in their respective protein levels. These changes were not present in cerebellum of suicide subjects. Also, these changes were present in all suicide subjects irrespective of psychiatric diagnosis. Our findings of reduced activation and altered expression of specific PI 3-kinase regulatory and catalytic subunit isoforms demonstrate abnormalities in this signaling pathway in postmortem brain of suicide subjects and suggest possible involvement of aberrant PI 3-kinase signaling in the pathogenic mechanisms of suicide.
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Affiliation(s)
- Yogesh Dwivedi
- Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL 60612, USA.
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76
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Zunder ER, Knight ZA, Houseman BT, Apsel B, Shokat KM. Discovery of drug-resistant and drug-sensitizing mutations in the oncogenic PI3K isoform p110 alpha. Cancer Cell 2008; 14:180-92. [PMID: 18691552 PMCID: PMC2720137 DOI: 10.1016/j.ccr.2008.06.014] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 05/19/2008] [Accepted: 06/25/2008] [Indexed: 11/27/2022]
Abstract
p110 alpha (PIK3CA) is the most frequently mutated kinase in human cancer, and numerous drugs targeting this kinase are currently in preclinical development or early-stage clinical trials. Clinical resistance to protein kinase inhibitors frequently results from point mutations that block drug binding; similar mutations in p110 alpha are likely, but currently none have been reported. Using a S. cerevisiae screen against a structurally diverse panel of PI3K inhibitors, we have identified a potential hotspot for resistance mutations (I800), a drug-sensitizing mutation (L814C), and a surprising lack of resistance mutations at the "gatekeeper" residue. Our analysis further reveals that clinical resistance to these drugs may be attenuated by using multitargeted inhibitors that simultaneously inhibit additional PI3K pathway members.
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Affiliation(s)
- Eli R. Zunder
- Graduate Group in Biophysics, University of California, San Francisco, California 94158
| | - Zachary A. Knight
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021
| | - Benjamin T. Houseman
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94143
| | - Beth Apsel
- Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, CA 94158, USA
| | - Kevan M. Shokat
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94143
- Howard Hughes Medical Institute, University of California, San Francisco, California 94143
- Department of Chemistry, University of California, Berkeley, California 94720
- Correspondence: , phone: 415-514-0472, fax: 415-514-0822
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77
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Mercado-Gómez O, Hernández-Fonseca K, Villavicencio-Queijeiro A, Massieu L, Chimal-Monroy J, Arias C. Inhibition of Wnt and PI3K signaling modulates GSK-3beta activity and induces morphological changes in cortical neurons: role of tau phosphorylation. Neurochem Res 2008; 33:1599-609. [PMID: 18461448 DOI: 10.1007/s11064-008-9714-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 04/09/2008] [Indexed: 01/27/2023]
Abstract
Glycogen synthase kinase GSK-3beta has been identified as one of the major candidates mediating tau hyperphosphorylation at the same sites as those present in tau protein in brain from Alzheimer's disease (AD) patients. However, the signal transduction pathways involved in the abnormal activation of GSK-3beta, have not been completely elucidated. GSK-3beta activity is repressed by the canonical Wnt signaling pathway, but it is also modulated through the PI3K/Akt route. Recent studies have suggested that Wnt signaling might be involved in the pathophysiology of AD. On the other hand, modulators of the PI3K pathway might be reduced during aging leading to a sustained activation of GSK-3beta, which in turn would increase the risk of tau hyperphosphorylation. The role of Wnt and PI3K signaling inhibition on the extent of tau phosphorylation and neuronal morphology has not been completely elucidated. Thus, in the present investigation we analyzed the effects of different negative modulators of the Wnt and the PI3K pathways on GSK-3beta activation and phosphorylation of tau at the PHF-1 epitope in cortical cultured neurons and hippocampal slices from adult rat brain. Changes in the microtubule network were also studied. We found that a variety of Wnt and PI3K inhibitors, significantly increased tau phosphorylation at the PHF-1 site, induced the disarrangement of the microtubule network and the accumulation of tau within cell bodies. These changes correlated with alterations in neuronal morphology.
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Affiliation(s)
- Octavio Mercado-Gómez
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, P.O. Box AP 70-228, Mexico, DF, 04510, Mexico
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78
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Lavin MF, Gueven N, Grattan-Smith P. Defective responses to DNA single- and double-strand breaks in spinocerebellar ataxia. DNA Repair (Amst) 2008; 7:1061-76. [PMID: 18467193 DOI: 10.1016/j.dnarep.2008.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Failure to maintain the integrity of DNA/chromatin can result in genome instability and an increased risk of cancer. The description of a number of human genetic disorders characterised not only by cancer predisposition but by a broader phenotype including neurodegeneration suggests that maintaining genome stability is also important for preserving post-mitotic neurons. The identification of genes associated with other neurodegenerative disorders provides further evidence for the importance of DNA damage response and DNA repair genes in protecting against neurodegeneration. This theme is further developed in this review.
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Affiliation(s)
- Martin F Lavin
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia.
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79
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Hausott B, Schlick B, Vallant N, Dorn R, Klimaschewski L. Promotion of neurite outgrowth by fibroblast growth factor receptor 1 overexpression and lysosomal inhibition of receptor degradation in pheochromocytoma cells and adult sensory neurons. Neuroscience 2008; 153:461-73. [DOI: 10.1016/j.neuroscience.2008.01.083] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 01/28/2008] [Accepted: 01/28/2008] [Indexed: 11/24/2022]
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80
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Kim BW, Choi M, Kim YS, Park H, Lee HR, Yun CO, Kim EJ, Choi JS, Kim S, Rhim H, Kaang BK, Son H. Vascular endothelial growth factor (VEGF) signaling regulates hippocampal neurons by elevation of intracellular calcium and activation of calcium/calmodulin protein kinase II and mammalian target of rapamycin. Cell Signal 2008; 20:714-25. [DOI: 10.1016/j.cellsig.2007.12.009] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 12/12/2007] [Accepted: 12/12/2007] [Indexed: 01/17/2023]
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81
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Kumamaru E, Numakawa T, Adachi N, Yagasaki Y, Izumi A, Niyaz M, Kudo M, Kunugi H. Glucocorticoid prevents brain-derived neurotrophic factor-mediated maturation of synaptic function in developing hippocampal neurons through reduction in the activity of mitogen-activated protein kinase. Mol Endocrinol 2007; 22:546-58. [PMID: 18096693 DOI: 10.1210/me.2007-0264] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
An increased level of glucocorticoid may be related to the pathophysiology of depressive disorder. The involvement of brain-derived neurotrophic factor (BDNF) in the antidepressive effect has also been suggested; however, the possible influence of glucocorticoid on the action of BDNF in the developing central nervous system has not been elucidated. In this study, we investigated the effect of glucocorticoid (dexamethasone, DEX) on synaptic maturation and function enhanced by BDNF in early developing hippocampal neurons. In the immature stage, BDNF increased the outgrowth of dendrites and the expression of synaptic proteins including glutamate receptors and presynaptic proteins. Pretreatment with DEX significantly inhibited the BDNF-dependent up-regulation of both dendritic outgrowth and synaptic proteins. In the more mature stage, the BDNF-reinforced postsynaptic Ca(2+) influx was decreased by DEX. BDNF-enhanced presynaptic glutamate release was also suppressed. RU486, a glucocorticoid receptor antagonist, canceled the DEX-dependent blocking effect on the action of BDNF. After down-regulation of glucocorticoid receptor by small interfering RNA application, no inhibitory effect of DEX on the BDNF-increased synaptic proteins was observed. Interestingly, the BDNF-activated MAPK/ERK pathway, which is an essential intracellular signaling pathway for the BDNF-increased synaptic proteins, was reduced by DEX. These results suggest that BDNF-mediated synaptic maturation is disturbed after neurons are exposed to high-level glucocorticoid in their development stage.
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Affiliation(s)
- Emi Kumamaru
- Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1, Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
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82
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Duchemin AM, Ren Q, Neff NH, Hadjiconstantinou M. GM1-induced activation of phosphatidylinositol 3-kinase: involvement of Trk receptors. J Neurochem 2007; 104:1466-77. [DOI: 10.1111/j.1471-4159.2007.05088.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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83
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Eickholt BJ, Ahmed AI, Davies M, Papakonstanti EA, Pearce W, Starkey ML, Bilancio A, Need AC, Smith AJH, Hall SM, Hamers FP, Giese KP, Bradbury EJ, Vanhaesebroeck B. Control of axonal growth and regeneration of sensory neurons by the p110delta PI 3-kinase. PLoS One 2007; 2:e869. [PMID: 17846664 PMCID: PMC1959241 DOI: 10.1371/journal.pone.0000869] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Accepted: 08/16/2007] [Indexed: 12/13/2022] Open
Abstract
The expression and function of the 8 distinct catalytic isoforms of PI 3-kinase (PI3K) in the nervous system are unknown. Whereas most PI3Ks have a broad tissue distribution, the tyrosine kinase-linked p110δ isoform has previously been shown to be enriched in leukocytes. Here we report that p110δ is also highly expressed in the nervous system. Inactivation of p110δ in mice did not affect gross neuronal development but led to an increased vulnerability of dorsal root ganglia neurons to exhibit growth cone collapse and decreases in axonal extension. Loss of p110δ activity also dampened axonal regeneration following peripheral nerve injury in adult mice and impaired functional recovery of locomotion. p110δ inactivation resulted in reduced neuronal signaling through the Akt protein kinase, and increased activity of the small GTPase RhoA. Pharmacological inhibition of ROCK, a downstream effector of RhoA, restored axonal extension defects in neurons with inactive p110δ, suggesting a key role of RhoA in p110δ signaling in neurons. Our data identify p110δ as an important signaling component for efficient axonal elongation in the developing and regenerating nervous system.
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Affiliation(s)
- Britta J Eickholt
- Medical Research Council Centre for Developmental Neurobiology, King's College London, London, United Kingdom.
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84
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Nizhynska V, Neumueller R, Herbst R. Phosphoinositide 3-kinase acts through RAC and Cdc42 during agrin-induced acetylcholine receptor clustering. Dev Neurobiol 2007; 67:1047-58. [PMID: 17565704 DOI: 10.1002/dneu.20371] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The formation of the neuromuscular junction (NMJ) is regulated by the nerve-derived heparan sulfate proteoglycan agrin and the muscle-specific kinase MuSK. Agrin induces a signal transduction pathway via MuSK, which promotes the reorganization of the postsynaptic muscle membrane. Activation of MuSK leads to the phosphorylation and redistribution of acetylcholine receptors (AChRs) and other postsynaptic proteins to synaptic sites. The accumulation of high densities of AChRs at postsynaptic regions represents a hallmark of NMJ formation and is required for proper NMJ function. Here we show that phosphoinositide 3-kinase (PI3-K) represents a component of the agrin/MuSK signaling pathway. Muscle cells treated with specific PI3-K inhibitors are unable to form full-size AChR clusters in response to agrin and AChR phosphorylation is reduced. Moreover, agrin-induced activation of Rac and Cdc42 is impaired in the presence of PI3-K inhibitors. PI3-K is localized to the postsynaptic muscle membrane consistent with a role during agrin/MuSK signaling. These results put PI3-K downstream of MuSK as regulator of AChR phosphorylation and clustering. Its role during agrin-stimulated Rac and Cdc42 activation suggests a critical function during cytoskeletal reorganizations, which lead to the redistribution of actin-anchored AChRs.
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Affiliation(s)
- Viktoria Nizhynska
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
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85
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Jia Y, Subramanian KK, Erneux C, Pouillon V, Hattori H, Jo H, You J, Zhu D, Schurmans S, Luo HR. Inositol 1,3,4,5-tetrakisphosphate negatively regulates phosphatidylinositol-3,4,5- trisphosphate signaling in neutrophils. Immunity 2007; 27:453-67. [PMID: 17825589 PMCID: PMC2084373 DOI: 10.1016/j.immuni.2007.07.016] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2007] [Revised: 06/15/2007] [Accepted: 07/30/2007] [Indexed: 01/24/2023]
Abstract
Many neutrophil functions are regulated by phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3) that mediates protein membrane translocation via binding to pleckstrin homolog (PH) domains within target proteins. Here we show that inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4), a cytosolic small molecule, bound the same PH domain of target proteins and competed for binding to PtdIns(3,4,5)P3. In neutrophils, chemoattractant stimulation triggered rapid elevation in Ins(1,3,4,5)P4 concentration. Depletion of Ins(1,3,4,5)P4 by deleting the gene encoding InsP3KB, which converts Ins(1,4,5)P3 to Ins(1,3,4,5)P4, enhanced membrane translocation of the PtdIns(3,4,5)P3-specific PH domain. This led to enhanced sensitivity to chemoattractant stimulation, elevated superoxide production, and enhanced neutrophil recruitment to inflamed peritoneal cavity. On the contrary, augmentation of intracellular Ins(1,3,4,5)P4 concentration blocked PH domain-mediated membrane translocation of target proteins and dramatically decreased the sensitivity of neutrophils to chemoattractant stimulation. These findings establish a role for Ins(1,3,4,5)P4 in cellular signal transduction pathways and provide another mechanism for modulating PtdIns(3,4,5)P3 signaling in neutrophils.
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Affiliation(s)
- Yonghui Jia
- Department of Pathology, Harvard Medical School, Dana-Farber/Harvard Cancer Center, Department of Lab Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115, USA
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86
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Moore CD, Thacker EE, Larimore J, Gaston D, Underwood A, Kearns B, Patterson SI, Jackson T, Chapleau C, Pozzo-Miller L, Theibert A. The neuronal Arf GAP centaurin alpha1 modulates dendritic differentiation. J Cell Sci 2007; 120:2683-93. [PMID: 17635995 PMCID: PMC2810648 DOI: 10.1242/jcs.006346] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Centaurin alpha1 is an Arf GTPase-activating protein (GAP) that is highly expressed in the nervous system. In the current study, we show that endogenous centaurin alpha1 protein is localized in the synaptosome fraction, with peak expression in early postnatal development. In cultured dissociated hippocampal neurons, centaurin alpha1 localizes to dendrites, dendritic spines and the postsynaptic region. siRNA-mediated knockdown of centaurin alpha1 levels or overexpression of a GAP-inactive mutant of centaurin alpha1 leads to inhibition of dendritic branching, dendritic filopodia and spine-like protrusions in dissociated hippocampal neurons. Overexpression of wild-type centaurin alpha1 in cultured hippocampal neurons in early development enhances dendritic branching, and increases dendritic filopodia and lamellipodia. Both filopodia and lamellipodia have been implicated in dendritic branching and spine formation. Following synaptogenesis in cultured neurons, wild-type centaurin alpha1 expression increases dendritic filopodia and spine-like protrusions. Expression of a GAP-inactive mutant diminishes spine density in CA1 pyramidal neurons within cultured organotypic hippocampal slice cultures. These data support the conclusion that centaurin alpha1 functions through GAP-dependent Arf regulation of dendritic branching and spines that underlie normal dendritic differentiation and development.
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Affiliation(s)
- Carlene D. Moore
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Erin E. Thacker
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jennifer Larimore
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - David Gaston
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Alison Underwood
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Brian Kearns
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Sean I. Patterson
- IHEM-CONICET, Departmento de Morfo-Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Trevor Jackson
- Departments of Physiology and Dermatology, School of Clinical and Laboratory Sciences, Medical School, University of Newcastle upon Tyne, NE2 4HH, UK
| | - Chris Chapleau
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lucas Pozzo-Miller
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Anne Theibert
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Author for correspondence ()
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87
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Buxbaum JD, Cai G, Chaste P, Nygren G, Goldsmith J, Reichert J, Anckarsäter H, Rastam M, Smith CJ, Silverman JM, Hollander E, Leboyer M, Gillberg C, Verloes A, Betancur C. Mutation screening of the PTEN gene in patients with autism spectrum disorders and macrocephaly. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:484-91. [PMID: 17427195 PMCID: PMC3381648 DOI: 10.1002/ajmg.b.30493] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mutations in the PTEN gene are associated with a broad spectrum of disorders, including Cowden syndrome (CS), Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome, and Lhermitte-Duclos disease. In addition, PTEN mutations have been described in a few patients with autism spectrum disorders (ASDs) and macrocephaly. In this study, we screened the PTEN gene for mutations and deletions in 88 patients with ASDs and macrocephaly (defined as >or=2 SD above the mean). Mutation analysis was performed by direct sequencing of all exons and flanking regions, as well as the promoter region. Dosage analysis of PTEN was carried out using multiplex ligation-dependent probe amplification (MLPA). No partial or whole gene deletions were observed. We identified a de novo missense mutation (D326N) in a highly conserved amino acid in a 5-year-old boy with autism, mental retardation, language delay, extreme macrocephaly (+9.6 SD) and polydactyly of both feet. Polydactyly has previously been described in two patients with Lhermitte-Duclos disease and CS and is thus likely to be a rare sign of PTEN mutations. Our findings suggest that PTEN mutations are a relatively infrequent cause of ASDs with macrocephaly. Screening of PTEN mutations is warranted in patients with autism and pronounced macrocephaly, even in the absence of other features of PTEN-related tumor syndromes.
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Affiliation(s)
- Joseph D. Buxbaum
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Guiqing Cai
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Pauline Chaste
- INSERM U513, Créteil, France
- Service de Psychopathologie de l’Enfant et de l’Adolescent, AP-HP, Hôpital Robert Debré, Paris, France
| | - Gudrun Nygren
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
| | - Juliet Goldsmith
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Jennifer Reichert
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Henrik Anckarsäter
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
| | - Maria Rastam
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
| | - Christopher J. Smith
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Jeremy M. Silverman
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Eric Hollander
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Marion Leboyer
- INSERM U513, Créteil, France
- Department of Psychiatry, AP-HP, Hôpital Henri Mondor et Hôpital Albert Chenevier, Créteil, France
| | - Christopher Gillberg
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
- Department of Psychiatry, Saint George’s Hospital Medical School, London, United Kingdom
| | - Alain Verloes
- Department of Genetics, AP-HP, Hôpital Robert Debré, Paris, France
| | - Catalina Betancur
- INSERM U513, Créteil, France
- Correspondence to: Dr. Catalina Betancur, INSERM U513, Faculté de Médecine, 8 rue du Général Sarrail, 94010 Créteil, Cedex, France.
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88
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Martins RAP, Pearson RA. Control of cell proliferation by neurotransmitters in the developing vertebrate retina. Brain Res 2007; 1192:37-60. [PMID: 17597590 DOI: 10.1016/j.brainres.2007.04.076] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 04/04/2007] [Accepted: 04/20/2007] [Indexed: 01/24/2023]
Abstract
In the developing vertebrate retina, precise coordination of retinal progenitor cell proliferation and cell-cycle exit is essential for the formation of a functionally mature retina. Unregulated or disrupted cell proliferation may lead to dysplasia, retinal degeneration or retinoblastoma. Both cell-intrinsic and -extrinsic factors regulate the proliferation of progenitor cells during CNS development. There is now growing evidence that in the developing vertebrate retina, both slow and fast neurotransmitter systems modulate the proliferation of retinal progenitor cells. Classic neurotransmitters, such as GABA (gamma-amino butyric acid), glycine, glutamate, ACh (acetylcholine) and ATP (adenosine triphosphate) are released, via vesicular or non-vesicular mechanisms, into the immature retinal environment. Furthermore, these neurotransmitters signal through functional receptors even before synapses are formed. Recent evidence indicates that the activation of purinergic and muscarinic receptors may regulate the cell-cycle machinery and consequently the expansion of the retinal progenitor pool. Interestingly, GABA and glutamate appear to have opposing roles, inducing retinal progenitor cell-cycle exit. In this review, we present recent findings that begin to elucidate the roles of neurotransmitters as regulators of progenitor cell proliferation at early stages of retinal development. These studies also raise several new questions, including how these neurotransmitters regulate specific cell-cycle pathways and the mechanisms by which retinal progenitor cells integrate the signals from neurotransmitters and other exogenous factors during vertebrate retina development.
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Affiliation(s)
- Rodrigo A P Martins
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, MS323, Memphis, TN 38105, USA.
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89
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Cosker KE, Eickholt BJ. Phosphoinositide 3-kinase signalling events controlling axonal morphogenesis. Biochem Soc Trans 2007; 35:207-10. [PMID: 17371239 DOI: 10.1042/bst0350207] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The establishment of neuronal morphology is essential for the formation of the nervous system. In general, neurons undergo a developmental programme during which their immature processes are specified into one axon and several dendrites. Extension of axons and dendrites is then critical for the establishment of appropriate connectivity. A body of work implicates the PI3K (phosphoinositide 3-kinase) signalling pathway to be crucial during the various events leading to the formation of neuronal circuit. In this review, we will focus specifically on the function of PI3K and downstream signalling cascades that control the establishment of axonal specification and elongation.
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Affiliation(s)
- K E Cosker
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
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90
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Niyaz M, Numakawa T, Matsuki Y, Kumamaru E, Adachi N, Kitazawa H, Kunugi H, Kudo M. MCI-186 prevents brain tissue from neuronal damage in cerebral infarction through the activation of intracellular signaling. J Neurosci Res 2007; 85:2933-42. [PMID: 17628025 DOI: 10.1002/jnr.21412] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The mechanism by which MCI-186 (3-methyl-1-phenyl-2-prazolin-5-one) exerts protective effects during cerebral infarction, other than its function as a radical scavenger, has not been fully elucidated. Here, we found that MCI-186 stimulates intracellular survival signaling in vivo and in vitro. In a rat infarction model, the infarct area was significantly smaller and the degree of edema was reduced in MCI-186-treated animals. In the MCI-186-treated rats, the number of single stranded (ss) DNA-positive damaged cells in the peri-infarct area was decreased compared with the control, suggesting that MCI-186 protects cerebral tissues from cell damage. To clarify the mechanisms underlying the effect of MCI-186, we also examined the survival-promoting effect of this agent on cultured cortical neurons. In this in vitro system, MCI-186 blocked serum-free induced neuronal cell death. Interestingly, an increase in the activation of both Akt (a component of the PI3 kinase pathway) and ERK (a component of the MAP kinase pathway) was observed in the cortical cultures after MCI-186 exposure. Furthermore, the MCI-186-dependent survival effect in vitro was blocked by U0126, an MEK (an upstream of ERK) inhibitor, and also by LY294002, a PI3 kinase inhibitor. We also observed similar increases in the activation of Akt and ERK in the in vivo model, further suggesting that the antiapoptotic role of MCI-186 is mediated via the PI3 kinase and MAP kinase signaling pathways. We therefore conclude that, in addition to its role as a free radical scavenger, MCI-186 functions as an antiapoptotic factor by enhancing intracellular survival signaling.
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Affiliation(s)
- Madinyet Niyaz
- Department of Pathology, Tokyo Medical University, Tokyo, Japan
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91
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Zhu D, Hattori H, Jo H, Jia Y, Subramanian KK, Loison F, You J, Le Y, Honczarenko M, Silberstein L, Luo HR. Deactivation of phosphatidylinositol 3,4,5-trisphosphate/Akt signaling mediates neutrophil spontaneous death. Proc Natl Acad Sci U S A 2006; 103:14836-41. [PMID: 16988010 PMCID: PMC1595438 DOI: 10.1073/pnas.0605722103] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Indexed: 01/24/2023] Open
Abstract
Neutrophil spontaneous death plays essential roles in neutrophil homeostasis and resolution of inflammation, whereas the underlying molecular mechanisms are still ill-defined. Neutrophils die because of programmed cell death or apoptosis. However, treatment with inhibitor of caspases, which are responsible for the majority of apoptotic cell deaths, does not prevent the spontaneous death of neutrophils. PKB/Akt possesses prosurvival and antiapoptotic activities in a variety of cells. In this study, we show that Akt activity decreases dramatically during the course of neutrophil death. Both phosphatidylinositol 3-kinase and Akt inhibitors enhance neutrophil death. Conditions delaying neutrophil death, such as treatment with granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, or IFN-gamma, restore Akt activity. Finally, we demonstrate that neutrophils depleted of PTEN, a phosphatidylinositol 3'-phosphatase that negatively regulates Akt activity, live much longer than WT neutrophils. Thus, we establish Akt deactivation as a causal mediator of neutrophil spontaneous death.
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Affiliation(s)
- Daocheng Zhu
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Hidenori Hattori
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Hakryul Jo
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Yonghui Jia
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Kulandayan K. Subramanian
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Fabien Loison
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Jian You
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Yi Le
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Marek Honczarenko
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Leslie Silberstein
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
| | - Hongbo R. Luo
- Department of Pathology, Joint Program in Transfusion Medicine, Harvard Medical School, and Department of Laboratory Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115
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92
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van der Heide LP, Ramakers GMJ, Smidt MP. Insulin signaling in the central nervous system: Learning to survive. Prog Neurobiol 2006; 79:205-21. [PMID: 16916571 DOI: 10.1016/j.pneurobio.2006.06.003] [Citation(s) in RCA: 299] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 06/19/2006] [Accepted: 06/23/2006] [Indexed: 12/23/2022]
Abstract
Insulin is best known for its role in peripheral glucose homeostasis. Less studied, but not less important, is its role in the central nervous system. Insulin and its receptor are located in the central nervous system and are both implicated in neuronal survival and synaptic plasticity. Interestingly, over the past few years it has become evident that the effects of insulin, on neuronal survival and synaptic plasticity, are mediated by a common signal transduction cascade, which has been identified as "the PI3K route". This route has turned out to be a major integrator of insulin signaling in the brain. A pronounced feature of this insulin-activated route is that it promotes survival by directly inactivating the pro-apoptotic machinery. Interestingly, it is this same route that is required for the induction of long-term potentiation and depression, basic processes underlying learning and memory. This leads to the hypothesis that the PI3K route forms a direct link between learning and memory and neuronal survival. The implications of this hypothesis are far reaching, since it provides an explanation why insulin has beneficial effects on learning and memory and how synaptic activity can prevent cellular degeneration. Applying this knowledge may provide novel therapeutic approaches in the treatment of neurodegenerative diseases such as Alzheimer's disease.
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Affiliation(s)
- Lars P van der Heide
- Rudolf Magnus Institute of Neuroscience, Department of Pharmacology and Anatomy, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
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93
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Tohda C, Hashimoto I, Kuboyama T, Komatsu K. Metabolite 1 of protopanaxadiol-type saponins, an axonal regenerative factor, stimulates teneurin-2 linked by PI3-kinase cascade. Neuropsychopharmacology 2006; 31:1158-64. [PMID: 16292329 DOI: 10.1038/sj.npp.1300943] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We previously showed that 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (M1), a metabolite of protopanaxadiol-type ginseng saponins by intestinal bacteria had axonal extension activity in degenerated neurons, and improved memory disorder and synaptic loss induced by an active fragment of amyloid beta, Abeta(25-35). It is unknown how M1 shows these effects in neurons. To clarify the signal transduction mechanism of M1-induced axonal extension, phosphorylated proteins by M1 stimulation were identified because most cellular signal pathways are regulated by phosphorylation/dephosphorylation. The combination of immunoprecipitation and MALDI-TOF-MS revealed that teneurin-2 and mPar3 were specifically phosphorylated by M1 stimulation. Because mPar3 is known as an axonal specifying molecule and to be regulated by phosphatidylinositol 3-kinase (PI3-kinase), the involvement of teneurin-2 and PI3-kinase in the M1 signal was studied. In teneurin-2-deficient cortical neurons, M1-induced axonal extension and PI3-kinase activation were significantly inhibited. In addition, treatment with PI3-kinase inhibitor also reduced M1-induced axonal extension. These results suggest that M1 induces axonal outgrowth through the teneurin-2-PI3-kinase cascade.
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Affiliation(s)
- Chihiro Tohda
- Division of Biofunctional Evaluation, Research Center for Ethnomedicine, Institute of Natural Medicine, University of Toyama, Sugitani, Toyama, Japan.
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94
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Numakawa Y, Numakawa T, Matsumoto T, Yagasaki Y, Kumamaru E, Kunugi H, Taguchi T, Niki E. Vitamin E protected cultured cortical neurons from oxidative stress-induced cell death through the activation of mitogen-activated protein kinase and phosphatidylinositol 3-kinase. J Neurochem 2006; 97:1191-202. [PMID: 16686696 DOI: 10.1111/j.1471-4159.2006.03827.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The role of vitamin E in the CNS has not been fully elucidated. In the present study, we found that pre-treatment with vitamin E analogs including alphaT (alpha-tocopherol), alphaT3 (alpha -tocotrienol), gammaT, and gammaT3 for 24 h prevented the cultured cortical neurons from cell death in oxidative stress stimulated by H2O2, while Trolox, a cell-permeable analog of alphaT, did not. The preventive effect of alphaT was dependent on de novo protein synthesis. Furthermore, we found that alphaT exposure induced the activation of both the MAP kinase (MAPK) and PI3 kinase (PI3K) pathways and that the alphaT-dependent survival effect was blocked by the inhibitors, U0126 (an MAPK pathway inhibitor) or LY294002 (a PI3K pathway inhibitor). Interestingly, the up-regulation of Bcl-2 (survival promoting molecule) was induced by alphaT application. The up-regulation of Bcl-2 did not occur in the presence of U0126 or LY294002, suggesting that alphaT-up-regulated Bcl-2 is mediated by these kinase pathways. These observations suggest that vitamin E analogs play an essential role in neuronal maintenance and survival in the CNS.
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Affiliation(s)
- Yumiko Numakawa
- Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Midorigaoka, Ikeda, Osaka, Japan.
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95
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Tornieri K, Welshhans K, Geddis MS, Rehder V. Control of neurite outgrowth and growth cone motility by phosphatidylinositol-3-kinase. ACTA ACUST UNITED AC 2006; 63:173-92. [PMID: 16463277 DOI: 10.1002/cm.20115] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Phosphatidylinositol-3-kinase (PI-3K) has been reported to affect neurite outgrowth both in vivo and in vitro. Here we investigated the signaling pathways by which PI-3K affects neurite outgrowth and growth cone motility in identified snail neurons in vitro. Inhibition of PI-3K with wortmannin (2 microM) or LY 294002 (25 microM) resulted in a significant elongation of filopodia and in a slow-down of neurite outgrowth. Experiments using cytochalasin and blebbistatin, drugs that interfere with actin polymerization and myosin II activity, respectively, demonstrated that filopodial elongation resulting from PI-3K inhibition was dependent on actin polymerization. Inhibition of strategic kinases located downstream of PI-3K, such as Akt, ROCK, and MEK, also caused significant filopodial elongation and a slow-down in neurite outgrowth. Another growth cone parameter, filopodial number, was not affected by inhibition of PI-3K, Akt, ROCK, or MEK. A detailed study of growth cone behavior showed that the filopodial elongation induced by inhibiting PI-3K, Akt, ROCK, and MEK was achieved by increasing two motility parameters: the rate with which filopodia extend (extension rate) and the time that filopodia spend elongating. Whereas the inhibition of ROCK or Akt (both activated by the lipid kinase activity of PI-3K) and MEK (activated by the protein kinase activity of PI-3K) had additive effects, simultaneous inhibition of Akt and ROCK showed no additive effect. We further demonstrate that the effects on filopodial dynamics investigated were calcium-independent. Taken together, our results suggest that inhibition of PI-3K signaling results in filopodial elongation and a slow-down of neurite advance, reminiscent of growth cone searching behavior.
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Affiliation(s)
- Karine Tornieri
- Department of Biology, Georgia State University, Atlanta, Georgia 30302, USA
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96
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Jaworski J, Spangler S, Seeburg DP, Hoogenraad CC, Sheng M. Control of dendritic arborization by the phosphoinositide-3'-kinase-Akt-mammalian target of rapamycin pathway. J Neurosci 2006; 25:11300-12. [PMID: 16339025 PMCID: PMC6725892 DOI: 10.1523/jneurosci.2270-05.2005] [Citation(s) in RCA: 467] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The molecular mechanisms that determine the size and complexity of the neuronal dendritic tree are unclear. Here, we show that the phosphoinositide-3' kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway promotes the growth and branching of dendrites in cultured hippocampal neurons. Constitutively active mutants of Ras, PI3K, and Akt, or RNA interference (RNAi) knockdown of lipid phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome Ten), induced growth and elaboration of dendrites that was blocked by mTOR inhibitor rapamycin and/or by overexpression of eIF-4E binding protein 1 (4E-BP1), which inhibits translation of 5' capped mRNAs. The effect of PI3K on dendrites was lost in more mature neurons (>14 d in vitro). Dendritic complexity was reduced by inhibition of PI3K and by RNAi knockdown of mTOR or p70 ribosomal S6 kinase (p70S6K, an effector of mTOR). A rapamycin-resistant mutant of mTOR "rescued" the morphogenetic effects of PI3K in the presence of rapamycin. By regulating global and/or local protein translation, and as a convergence point for multiple signaling pathways, mTOR could play a central role in the control of dendrite growth and branching during development and in response to activity.
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Affiliation(s)
- Jacek Jaworski
- The Picower Institute for Learning and Memory, The Institute of Physical and Chemical Research (RIKEN), Massachusetts Institute of Technology Neuroscience Research Center, Cambridge, Massachusetts 02139, USA
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97
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Kumar V, Zhang MX, Swank MW, Kunz J, Wu GY. Regulation of dendritic morphogenesis by Ras-PI3K-Akt-mTOR and Ras-MAPK signaling pathways. J Neurosci 2006; 25:11288-99. [PMID: 16339024 PMCID: PMC6725910 DOI: 10.1523/jneurosci.2284-05.2005] [Citation(s) in RCA: 466] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Dendritic arborization and spine formation are critical for the functioning of neurons. Although many proteins have been identified recently as regulators of dendritic morphogenesis, the intracellular signaling pathways that control these processes are not well understood. Here we report that the Ras-phosphatidylinositol 3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway plays pivotal roles in the regulation of many aspects of dendrite formation. Whereas the PI3K-Akt-mTOR pathway alone controlled soma and dendrite size, a coordinated activation together with the Ras-mitogen-activated protein kinase signaling pathway was required for increasing dendritic complexity. Chronic inhibition of PI3K or mTOR reduced soma and dendrite size and dendritic complexity, as well as density of dendritic filopodia and spines, whereas a short-term inhibition promoted the formation of mushroom-shaped spines on cells expressing constitutively active mutants of Ras, PI3K, or Akt, or treated with the upstream activator BDNF. Together, our data underscore the central role of a spatiotemporally regulated key cell survival and growth pathway on trophic regulation of the coordinated development of dendrite size and shape.
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Affiliation(s)
- Vikas Kumar
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA
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98
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Giachino C, De Marchis S, Giampietro C, Parlato R, Perroteau I, Schütz G, Fasolo A, Peretto P. cAMP response element-binding protein regulates differentiation and survival of newborn neurons in the olfactory bulb. J Neurosci 2006; 25:10105-18. [PMID: 16267218 PMCID: PMC6725785 DOI: 10.1523/jneurosci.3512-05.2005] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The transcription factor cAMP response element-binding protein (CREB) is involved in multiple aspects of neuronal development and plasticity. Here, we demonstrate that CREB regulates specific phases of adult neurogenesis in the subventricular zone/olfactory bulb (SVZ/OB) system. Combining immunohistochemistry with bromodeoxyuridine treatments, cell tracer injections, cell transplants, and quantitative analyses, we show that although CREB is expressed by the SVZ neuroblasts throughout the neurogenic process, its phosphorylation is transient and parallels neuronal differentiation, increasing during the late phase of tangential migration and decreasing after dendrite elongation and spine formation. In vitro, inhibition of CREB function impairs morphological differentiation of SVZ-derived neuroblasts. Transgenic mice lacking CREB, in a null CREM genetic background, show reduced survival of newborn neurons in the OB. This finding is further supported by peripheral afferent denervation experiments resulting in downregulation of CREB phosphorylation in neuroblasts, the survival of which appears heavily impaired. Together, these findings provide evidence that CREB regulates differentiation and survival of newborn neurons in the OB.
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Affiliation(s)
- Claudio Giachino
- Department of Animal and Human Biology, University of Turin, 10123 Turin, Italy
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99
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Weisman GA, Wang M, Kong Q, Chorna NE, Neary JT, Sun GY, González FA, Seye CI, Erb L. Molecular determinants of P2Y2 nucleotide receptor function: implications for proliferative and inflammatory pathways in astrocytes. Mol Neurobiol 2006; 31:169-83. [PMID: 15953819 DOI: 10.1385/mn:31:1-3:169] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 11/15/2004] [Indexed: 01/05/2023]
Abstract
In the mammalian nervous system, P2 nucleotide receptors mediate neurotransmission, release of proinflammatory cytokines, and reactive astrogliosis. Extracellular nucleotides activate multiple P2 receptors in neurons and glial cells, including G protein-coupled P2Y receptors and P2X receptors, which are ligand-gated ion channels. In glial cells, the P2Y2 receptor subtype, distinguished by its ability to be equipotently activated by ATP and UTP, is coupled to pro-inflammatory signaling pathways. In situ hybridization studies with rodent brain slices indicate that P2Y2 receptors are expressed primarily in the hippocampus and cerebellum. Astrocytes express several P2 receptor subtypes, including P2Y2 receptors whose activation stimulates cell proliferation and migration. P2Y2 receptors, via an RGD (Arg-Gly-Asp) motif in their first extracellular loop, bind to alphavbeta3/beta5 integrins, whereupon P2Y2 receptor activation stimulates integrin signaling pathways that regulate cytoskeletal reorganization and cell motility. The C-terminus of the P2Y2 receptor contains two Src-homology-3 (SH3)-binding domains that upon receptor activation, promote association with Src and transactivation of growth factor receptors. Together, our results indicate that P2Y2 receptors complex with both integrins and growth factor receptors to activate multiple signaling pathways. Thus, P2Y2 receptors present novel targets to control reactive astrogliosis in neurodegenerative diseases.
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Affiliation(s)
- Gary A Weisman
- Department of Biochemistry and Neuroscience Program, University of Missouri-Columbia, Columbia, MO, USA.
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100
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Pocklington AJ, Cumiskey M, Armstrong JD, Grant SGN. The proteomes of neurotransmitter receptor complexes form modular networks with distributed functionality underlying plasticity and behaviour. Mol Syst Biol 2006; 2:2006.0023. [PMID: 16738568 PMCID: PMC1681474 DOI: 10.1038/msb4100041] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 11/22/2005] [Indexed: 12/31/2022] Open
Abstract
Neuronal synapses play fundamental roles in information processing, behaviour and disease. Neurotransmitter receptor complexes, such as the mammalian N-methyl-D-aspartate receptor complex (NRC/MASC) comprising 186 proteins, are major components of the synapse proteome. Here we investigate the organisation and function of NRC/MASC using a systems biology approach. Systematic annotation showed that the complex contained proteins implicated in a wide range of cognitive processes, synaptic plasticity and psychiatric diseases. Protein domains were evolutionarily conserved from yeast, but enriched with signalling domains associated with the emergence of multicellularity. Mapping of protein-protein interactions to create a network representation of the complex revealed that simple principles underlie the functional organisation of both proteins and their clusters, with modularity reflecting functional specialisation. The known functional roles of NRC/MASC proteins suggest the complex co-ordinates signalling to diverse effector pathways underlying neuronal plasticity. Importantly, using quantitative data from synaptic plasticity experiments, our model correctly predicts robustness to mutations and drug interference. These studies of synapse proteome organisation suggest that molecular networks with simple design principles underpin synaptic signalling properties with important roles in physiology, behaviour and disease.
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Affiliation(s)
| | - Mark Cumiskey
- Division of Neuroscience, Edinburgh University, Edinburgh, UK
- Wellcome Trust Sanger Institute, Cambridge, UK
| | | | - Seth G N Grant
- Division of Neuroscience, Edinburgh University, Edinburgh, UK
- Wellcome Trust Sanger Institute, Cambridge, UK
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