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Shpakov AO, Zorina II, Derkach KV. Hot Spots for the Use of Intranasal Insulin: Cerebral Ischemia, Brain Injury, Diabetes Mellitus, Endocrine Disorders and Postoperative Delirium. Int J Mol Sci 2023; 24:3278. [PMID: 36834685 PMCID: PMC9962062 DOI: 10.3390/ijms24043278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/27/2023] [Accepted: 01/31/2023] [Indexed: 02/11/2023] Open
Abstract
A decrease in the activity of the insulin signaling system of the brain, due to both central insulin resistance and insulin deficiency, leads to neurodegeneration and impaired regulation of appetite, metabolism, endocrine functions. This is due to the neuroprotective properties of brain insulin and its leading role in maintaining glucose homeostasis in the brain, as well as in the regulation of the brain signaling network responsible for the functioning of the nervous, endocrine, and other systems. One of the approaches to restore the activity of the insulin system of the brain is the use of intranasally administered insulin (INI). Currently, INI is being considered as a promising drug to treat Alzheimer's disease and mild cognitive impairment. The clinical application of INI is being developed for the treatment of other neurodegenerative diseases and improve cognitive abilities in stress, overwork, and depression. At the same time, much attention has recently been paid to the prospects of using INI for the treatment of cerebral ischemia, traumatic brain injuries, and postoperative delirium (after anesthesia), as well as diabetes mellitus and its complications, including dysfunctions in the gonadal and thyroid axes. This review is devoted to the prospects and current trends in the use of INI for the treatment of these diseases, which, although differing in etiology and pathogenesis, are characterized by impaired insulin signaling in the brain.
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Affiliation(s)
- Alexander O. Shpakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223 St. Petersburg, Russia
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Jana M, Ghosh S, Pahan K. Upregulation of Myelin Gene Expression by a Physically-Modified Saline via Phosphatidylinositol 3-Kinase-Mediated Activation of CREB: Implications for Multiple Sclerosis. Neurochem Res 2017; 43:407-419. [PMID: 29143164 PMCID: PMC5799355 DOI: 10.1007/s11064-017-2435-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 10/03/2017] [Accepted: 11/09/2017] [Indexed: 12/29/2022]
Abstract
An increase in central nervous system (CNS) remyelination and a decrease in CNS inflammation are important steps to halt the progression of multiple sclerosis (MS). RNS60 is a bioactive aqueous solution generated by subjecting normal saline to Taylor–Couette–Poiseuille flow under elevated oxygen pressure. Recently we have demonstrated that RNS60 exhibits anti-inflammatory properties. Here, we describe promyelinating property of RNS60. RNS60, but not normal saline (NS), RNS10.3 (TCP-modified saline without excess oxygen) or PNS60 (saline containing excess oxygen without TCP modification), stimulated the expression of myelin-specific genes and proteins (myelin basic protein, MBP; myelin oligodendrocyte glycoprotein, MOG and proteolipid protein, PLP) in primary mouse oligodendroglia and mixed glial cells. While investigating the mechanisms, we found that RNS60 treatment induced the activation of cAMP response element binding protein (CREB) in oligodendrocytes, ultimately leading to the recruitment of CREB to the promoters of myelin-specific genes. Furthermore, activation of type 1A p110β/α, but not type 1B p110γ, phosphatidylinositol-3 (PI-3) kinase by RNS60 together with abrogation of RNS60-mediated activation of CREB and upregulation of myelin genes by LY294002 (a specific inhibitor of PI-3 kinase) suggest that RNS60 upregulates the activation of CREB and the expression of myelin-specific molecules in oligodendrocytes via activation of PI3 kinase. These results highlight a novel promyelinating property of RNS60, which may be of benefit for MS and other demyelinating disorders.
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Affiliation(s)
- Malabendu Jana
- Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison St, Suite 310, Chicago, IL, 60612, USA
| | - Supurna Ghosh
- Revalesio Corporation, 1200 East D Street, Tacoma, WA, 98421, USA
| | - Kalipada Pahan
- Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison St, Suite 310, Chicago, IL, 60612, USA.
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Wang L, Sanford MT, Xin Z, Lin G, Lue TF. Role of Schwann cells in the regeneration of penile and peripheral nerves. Asian J Androl 2016; 17:776-82. [PMID: 25999359 PMCID: PMC4577590 DOI: 10.4103/1008-682x.154306] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Schwann cells (SCs) are the principal glia of the peripheral nervous system. The end point of SC development is the formation of myelinating and nonmyelinating cells which ensheath large and small diameter axons, respectively. They play an important role in axon regeneration after injury, including cavernous nerve injury that leads to erectile dysfunction (ED). Despite improvement in radical prostatectomy surgical techniques, many patients still suffer from ED postoperatively as surgical trauma causes traction injuries and local inflammatory changes in the neuronal microenvironment of the autonomic fibers innervating the penis resulting in pathophysiological alterations in the end organ. The aim of this review is to summarize contemporary evidence regarding: (1) the origin and development of SCs in the peripheral and penile nerve system; (2) Wallerian degeneration and SC plastic change following peripheral and penile nerve injury; (3) how SCs promote peripheral and penile nerve regeneration by secreting neurotrophic factors; (4) and strategies targeting SCs to accelerate peripheral nerve regeneration. We searched PubMed for articles related to these topics in both animal models and human research and found numerous studies suggesting that SCs could be a novel target for treatment of nerve injury-induced ED.
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Affiliation(s)
| | | | | | - Guiting Lin
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, CA, USA,
| | - Tom F Lue
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, CA, USA,
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mTORC1 is essential for early steps during Schwann cell differentiation of amniotic fluid stem cells and regulates lipogenic gene expression. PLoS One 2014; 9:e107004. [PMID: 25221943 PMCID: PMC4164523 DOI: 10.1371/journal.pone.0107004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 08/04/2014] [Indexed: 01/18/2023] Open
Abstract
Schwann cell development is hallmarked by the induction of a lipogenic profile. Here we used amniotic fluid stem (AFS) cells and focused on the mechanisms occurring during early steps of differentiation along the Schwann cell lineage. Therefore, we initiated Schwann cell differentiation in AFS cells and monitored as well as modulated the activity of the mechanistic target of rapamycin (mTOR) pathway, the major regulator of anabolic processes. Our results show that mTOR complex 1 (mTORC1) activity is essential for glial marker expression and expression of Sterol Regulatory Element-Binding Protein (SREBP) target genes. Moreover, SREBP target gene activation by statin treatment promoted lipogenic gene expression, induced mTORC1 activation and stimulated Schwann cell differentiation. To investigate mTORC1 downstream signaling we expressed a mutant S6K1, which subsequently induced the expression of the Schwann cell marker S100b, but did not affect lipogenic gene expression. This suggests that S6K1 dependent and independent pathways downstream of mTORC1 drive AFS cells to early Schwann cell differentiation and lipogenic gene expression. In conclusion our results propose that future strategies for peripheral nervous system regeneration will depend on ways to efficiently induce the mTORC1 pathway.
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Wnt/Rspondin/β-catenin signals control axonal sorting and lineage progression in Schwann cell development. Proc Natl Acad Sci U S A 2013; 110:18174-9. [PMID: 24151333 DOI: 10.1073/pnas.1310490110] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
During late Schwann cell development, immature Schwann cells segregate large axons from bundles, a process called "axonal radial sorting." Here we demonstrate that canonical Wnt signals play a critical role in radial sorting and assign a role to Wnt and Rspondin ligands in this process. Mice carrying β-catenin loss-of-function mutations show a delay in axonal sorting; conversely, gain-of-function mutations result in accelerated sorting. Sorting deficits are accompanied by abnormal process extension, differentiation, and aberrant cell cycle exit of the Schwann cells. Using primary cultured Schwann cells, we analyze the upstream effectors, Wnt and Rspondin ligands that initiate signaling, and downstream genetic programs that mediate the Wnt response. Our analysis contributes to a better understanding of the mechanisms of Schwann cell development and fate decisions.
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Miyamoto N, Maki T, Pham LDD, Hayakawa K, Seo JH, Mandeville ET, Mandeville JB, Kim KW, Lo EH, Arai K. Oxidative stress interferes with white matter renewal after prolonged cerebral hypoperfusion in mice. Stroke 2013; 44:3516-21. [PMID: 24072001 DOI: 10.1161/strokeaha.113.002813] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND PURPOSE White matter injury caused by cerebral hypoperfusion may contribute to the pathophysiology of vascular dementia and stroke, but the underlying mechanisms remain to be fully defined. Here, we test the hypothesis that oxidative stress interferes with endogenous white matter repair by disrupting renewal processes mediated by oligodendrocyte precursor cells (OPCs). METHODS In vitro, primary rat OPCs were exposed to sublethal CoCl2 for 7 days to induce prolonged chemical hypoxic stress. Then, OPC proliferation/differentiation was assessed. In vivo, prolonged cerebral hypoperfusion was induced by bilateral common carotid artery stenosis in mice. Then, reactive oxygen species production, myelin density, oligodendrocyte versus OPC counts, and cognitive function were evaluated. To block oxidative stress, OPCs and mice were treated with the radical scavenger edaravone. RESULTS Prolonged chemical hypoxic stress suppressed OPC differentiation in vitro. Radical scavenging with edaravone ameliorated these effects. After 28 days of cerebral hypoperfusion in vivo, reactive oxygen species levels were increased in damaged white matter, along with the suppression of OPC-to-oligodendrocyte differentiation and loss of myelin staining. Concomitantly, mice showed functional deficits in working memory. Radical scavenging with edaravone rescued OPC differentiation, ameliorated myelin loss, and restored working memory function. CONCLUSIONS Our proof-of-concept study demonstrates that after prolonged cerebral hypoperfusion, oxidative stress interferes with white matter repair by disrupting OPC renewal mechanisms. Radical scavengers may provide a potential therapeutic approach for white matter injury in vascular dementia and stroke.
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Affiliation(s)
- Nobukazu Miyamoto
- From the Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (N.M., T.M., L.-D.D.P., K.H., J.H.S., E.T.M., E.H.L., K.A.); Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA (J.B.M.); and NeuroVascular Coordination Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences (J.H.S., K.-W.K.) and Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology (K.-W.K.), Seoul National University, Seoul, Korea
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Chen HL, Chew LJ, Packer RJ, Gallo V. Modulation of the Wnt/beta-catenin pathway in human oligodendroglioma cells by Sox17 regulates proliferation and differentiation. Cancer Lett 2013; 335:361-71. [PMID: 23474492 DOI: 10.1016/j.canlet.2013.02.058] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/19/2013] [Accepted: 02/24/2013] [Indexed: 02/07/2023]
Abstract
Oligodendrogliomas originate from oligodendrocyte progenitor cells (OPCs), whose development is regulated by the Sonic hedgehog and Wnt/beta-catenin pathways. We investigated the contribution of these pathways in the proliferation and differentiation of human oligodendroglioma cells (HOG). Inhibition of Hedgehog signaling with cyclopamine decreased cell survival and increased phosphorylated beta-catenin without altering myelin protein levels. Conversely, treatment of HOG with the Wnt antagonist secreted frizzled related protein (SFRP1), led to increased myelin protein levels and reduced cell proliferation, suggesting cell cycle arrest and differentiation. Unlike normal primary human OPCs, beta-catenin in HOG cells is not associated with endogenous Sox17 protein despite high levels of both proteins. Retroviral overexpression of recombinant Sox17 increased HOG cell cycle exit and apoptosis, and raised myelin protein levels and the percentage of O4(+) cells, indicating increased differentiation. Recombinant Sox17 also increased beta-catenin-TCF4-Sox17 complex formation and decreased total cellular levels of beta-catenin. These changes were associated with increased SFRP1, and reduced expression of Wnt-1 and Frizzled-1, -3 and -7 RNA, indicating that Sox17 induced a Hedgehog target, and regulated Wnt signaling at multiple levels. Our studies indicate that Wnt signaling regulates HOG cell cycle arrest and differentiation, and that recombinant Sox17 mediates modulation of the Wnt pathway through changes in beta-catenin, SFRP1 and Wnt/Frizzled expression. Our results thus identify Sox17 as a potential molecular target to include in HOG therapeutic strategies.
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Affiliation(s)
- Hui-Ling Chen
- Center for Neuroscience Research, Children's National Medical Center, Washington, DC 20010, USA
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Jana M, Mondal S, Gonzalez FJ, Pahan K. Gemfibrozil, a lipid-lowering drug, increases myelin genes in human oligodendrocytes via peroxisome proliferator-activated receptor-β. J Biol Chem 2012; 287:34134-48. [PMID: 22879602 DOI: 10.1074/jbc.m112.398552] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
An increase in CNS remyelination and a decrease in CNS inflammation are important steps to halt the progression of multiple sclerosis. Earlier studies have shown that gemfibrozil, a lipid-lowering drug, has anti-inflammatory properties. The current study identified another novel property of gemfibrozil in stimulating the expression of myelin-specific genes (myelin basic protein, myelin oligodendrocyte glycoprotein, 2',3'-cyclic-nucleotide 3'-phosphodiesterase, and proteolipid protein (PLP)) in primary human oligodendrocytes, mixed glial cells, and spinal cord organotypic cultures. Although gemfibrozil is a known activator of peroxisome proliferator-activated receptor-α (PPAR-α), we were unable to detect PPAR-α in either gemfibrozil-treated or untreated human oligodendrocytes, and gemfibrozil increased the expression of myelin genes in oligodendrocytes isolated from both wild type and PPAR-α(-/-) mice. On the other hand, gemfibrozil markedly increased the expression of PPAR-β but not PPAR-γ. Consistently, antisense knockdown of PPAR-β, but not PPAR-γ, abrogated the stimulatory effect of gemfibrozil on myelin genes in human oligodendrocytes. Gemfibrozil also did not up-regulate myelin genes in oligodendroglia isolated from PPAR-β(-/-) mice. Chromatin immunoprecipitation analysis showed that gemfibrozil induced the recruitment of PPAR-β to the promoter of PLP and myelin oligodendrocyte glycoprotein genes in human oligodendrocytes. Furthermore, gemfibrozil treatment also led to the recruitment of PPAR-β to the PLP promoter in vivo in the spinal cord of experimental autoimmune encephalomyelitis mice and suppression of experimental autoimmune encephalomyelitis symptoms in PLP-T cell receptor transgenic mice. These results suggest that gemfibrozil stimulates the expression of myelin genes via PPAR-β and that gemfibrozil, a prescribed drug for humans, may find further therapeutic use in demyelinating diseases.
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Affiliation(s)
- Malabendu Jana
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois 60612, USA
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Salis C, Davio C, Usach V, Urtasun N, Goitia B, Martinez-Vivot R, Pasquini JM, Setton-Avruj CP. Iron and holotransferrin induce cAMP-dependent differentiation of Schwann cells. Neurochem Int 2012; 61:798-806. [PMID: 22776360 DOI: 10.1016/j.neuint.2012.06.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 06/21/2012] [Accepted: 06/26/2012] [Indexed: 10/28/2022]
Abstract
The differentiation of myelin-forming Schwann cells (SC) is completed with the appearance of myelin proteins MBP and P(0) and a concomitant downregulation of markers GFAP and p75NTR, which are expressed by immature and adult non-myelin-forming SC. We have previously demonstrated that holotransferrin (hTf) can prevent SC dedifferentiation in culture (Salis et al., 2002), while apotransferrin (aTf) cannot. As a consequence, we used pure cultured SC and submitted them to serum deprivation in order to promote dedifferentiation and evaluate the prodifferentiating ability of ferric ammonium citrate (FAC) through the expression of MBP, P(0), p75NTR and c-myc. The levels of cAMP, CREB and p-CREB were also measured. Results show that Fe(3+), either in its free form or as hTf, can prevent the dedifferentiation promoted by serum withdrawal. Both FAC and hTf were proven to promote differentiation, probably through the increase in cAMP levels and CREB phosphorylation, as well as levels of reactive oxygen species. This effect was inhibited by deferroxamine (Dfx, an iron chelator), H9 (a cAMP-PKA antagonist) and N-acetylcysteine (NAC, a powerful antioxidant).
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Affiliation(s)
- C Salis
- Instituto de Química y Fisicoquímica Biológica (IQUIFIB), UBA-CONICET, Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires C1113AAD, Argentina
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10
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SRY-box containing gene 17 regulates the Wnt/β-catenin signaling pathway in oligodendrocyte progenitor cells. J Neurosci 2011; 31:13921-35. [PMID: 21957254 DOI: 10.1523/jneurosci.3343-11.2011] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The SRY-box (Sox) transcription factors regulate oligodendrocyte differentiation, but their signaling targets are largely unknown. We have identified a major signal transduction pathway regulated by Sox containing gene 17 (Sox17) in the oligodendrocyte lineage. Microarray analysis in oligodendrocyte progenitor cells (OPCs) after Sox17 attenuation revealed upregulated genes associated with cell cycle control and activation of the Wingless and integration site (Wnt)/β-catenin pathway. Sox17 knockdown also increases the levels of cyclin D1, Axin2, and activated β-catenin. In OPCs, the expression pattern of Sox17, cyclin D1, and secreted Frizzled-related protein-1 in the presence of platelet-derived growth factor (PDGF) was coordinately accelerated by addition of thyroid hormone, indicating differentiation-induced regulation of Sox17 targets. In developing white matter, decreased total β-catenin, activated β-catenin, and cyclin D1 levels coincided with the peak of Sox17 expression, and immunoprecipitates showed a developmentally regulated interaction among Sox17, T-cell transcription factor 4, and β-catenin proteins. In OPCs, PDGF stimulated phosphorylation of glycogen synthase 3β and the Wnt coreceptor LRP6, and enhanced β-catenin-dependent gene expression. Sox17 overexpression inhibited PDGF-induced TOPFLASH and cyclin D1 promoter activity, and decreased endogenous cyclin D1, activated β-catenin, as well as total β-catenin levels. Recombinant Sox17 prevented Wnt3a from repressing myelin protein expression, and inhibition of Sox17-mediated proteasomal degradation of β-catenin blocked myelin protein induction. These results indicate that Sox17 suppresses cyclin D1 expression and cell proliferation by directly antagonizing β-catenin, whose activity in OPCs is stimulated not only by Wnt3a, but also by PDGF. Our identification of downstream targets of Sox17 thus defines signaling pathways and molecular mechanisms in OPCs that are regulated by Sox17 during cell cycle exit and the onset of differentiation in oligodendrocyte development.
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11
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Doucette JR, Jiao R, Nazarali AJ. Age-related and cuprizone-induced changes in myelin and transcription factor gene expression and in oligodendrocyte cell densities in the rostral corpus callosum of mice. Cell Mol Neurobiol 2010; 30:607-29. [PMID: 20063055 DOI: 10.1007/s10571-009-9486-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 12/11/2009] [Indexed: 12/11/2022]
Abstract
During aging, there is a decrease both in the stability of central nervous system (CNS) myelin once formed and in the efficiency of its repair by oligodendrocytes (OLs). To study CNS remyelination during aging, we used the cuprizone (a copper chelator) mouse model. Inclusion of cuprizone in the diet kills mature OLs and demyelinates axons in the rostral corpus callosum (CC) of mice, which enabled us to characterize age-related changes (i.e., 2-16 months of age) in glial cell response during the recruitment (i.e., demyelination) and differentiation (i.e., remyelination) phases of myelin repair. We have found that the time between 12 and 16 months of age is a critical period during which there is an age-related decrease in the number of OL lineage cells (Olig2(Nuc)+ve/GFAP-ve cells) in the rostral CC of both control mice and mice recovering from cuprizone-induced demyelination. Our results also show there was an age-related impaired recruitment of progenitor cells to replace lost OLs in spite of there being no major age-related decrease in the size of the progenitor cell pool (PDGFalphaR+ve/GFAP-ve, and Olig2(Nuc) +ve/PDGFalphaR+ve cells). However, there were cuprizone-induced increased numbers of astrocyte progenitor cells (Olig2(Cyto)+ve/PDGFalphaR+ve) in these same mice; thus PDGFalphaR+ve progenitor cells in mice as old as 16 months of age retain the ability to differentiate into astrocytes, with this fate choice occurring following cytoplasmic translocation of Olig2. These data reveal for the first time age-related differences in the differentiation of PDGFalphaR+ve progenitor cells into OLs and astrocytes and lead us to suggest that during aging there must be a transcriptional switch mechanism in the progenitor cell fate choice in favor of astrocytes. This may at least partially explain the age-related decrease in efficiency of OL myelination and remyelination.
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Affiliation(s)
- J Ronald Doucette
- Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
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12
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p38 Mitogen-activated protein kinase regulates myelination. J Mol Neurosci 2007; 35:23-33. [PMID: 17994198 DOI: 10.1007/s12031-007-9011-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 09/15/2007] [Indexed: 12/16/2022]
Abstract
The p38 mitogen-activated protein kinase family is emerging as a crucial signaling molecule for a vast number of cellular functions including cell migration, proliferation, and differentiation. The function of p38 in myelination has only been recently addressed. Using pyridinyl imidazole-based p38 alpha/beta selective inhibitors, we have reported a critical role for this kinase in the regulation of myelination, specifically, in controlling the differentiation of Schwann cells, and oligodendrocytes, the myelinating glia of the peripheral and central nervous systems, respectively. These compounds inhibited the accumulation of myelin-cell-specific markers, including myelin-specific glycosphingolipids, myelin-associated glycoprotein, and myelin basic protein. More significantly, myelination of dorsal root ganglia neurons by oligodendrocytes was irreversibly blocked by p38 inhibitors. Our current studies are focusing on the molecular mechanisms by which p38 regulates oligodendrocyte and Schwann cell differentiation and its role in models of myelination and remyelination.
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Wegner M. A matter of identity: transcriptional control in oligodendrocytes. J Mol Neurosci 2007; 35:3-12. [PMID: 18401762 DOI: 10.1007/s12031-007-9008-8] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 08/26/2007] [Indexed: 01/30/2023]
Abstract
Oligodendrocyte development progresses from specification to terminal differentiation through several phases. By now, a number of transcription factors have been identified that are essential for one or more of these phases. They stem from transcription factor families with known roles in many developmental processes. Basic helix-loop-helix, homeodomain, and high-mobility-group containing transcription factors such as the Olig, Nkx, and Sox proteins have been particularly well studied. A complex picture has emerged in which these transcription factors interact in transcriptional networks and thereby combine and influence their respective activities as repressors or activators in such a way that stage- and cell-type specific gene expression is achieved during oligodendrocyte development.
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Affiliation(s)
- Michael Wegner
- Institut für Biochemie, Emil-Fischer-Zentrum, Universität Erlangen, Fahrstrasse 17, 91054 Erlangen, Germany.
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He Y, Dupree J, Wang J, Sandoval J, Li J, Liu H, Shi Y, Nave KA, Casaccia-Bonnefil P. The transcription factor Yin Yang 1 is essential for oligodendrocyte progenitor differentiation. Neuron 2007; 55:217-30. [PMID: 17640524 PMCID: PMC2034312 DOI: 10.1016/j.neuron.2007.06.029] [Citation(s) in RCA: 213] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 05/24/2007] [Accepted: 06/21/2007] [Indexed: 11/17/2022]
Abstract
The progression of progenitors to oligodendrocytes requires proliferative arrest and the activation of a transcriptional program of differentiation. While regulation of cell cycle exit has been extensively characterized, the molecular mechanisms responsible for the initiation of differentiation remain ill-defined. Here, we identify the transcription factor Yin Yang 1 (YY1) as a critical regulator of oligodendrocyte progenitor differentiation. Conditional ablation of yy1 in the oligodendrocyte lineage in vivo induces a phenotype characterized by defective myelination, ataxia, and tremor. At the cellular level, lack of yy1 arrests differentiation of oligodendrocyte progenitors after they exit from the cell cycle. At the molecular level, YY1 acts as a lineage-specific repressor of transcriptional inhibitors of myelin gene expression (Tcf4 and Id4), by recruiting histone deacetylase-1 to their promoters during oligodendrocyte differentiation. Thus, we identify YY1 as an essential component of the transcriptional network regulating the transition of oligodendrocyte progenitors from cell cycle exit to differentiation.
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Affiliation(s)
- Ye He
- Department of Neuroscience and Cell Biology, R. Wood Johnson Medical School, Piscataway, NJ 08854, USA
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15
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Lindsley A, Snider P, Zhou H, Rogers R, Wang J, Olaopa M, Kruzynska-Frejtag A, Koushik SV, Lilly B, Burch JB, Firulli AB, Conway. SJ. Identification and characterization of a novel Schwann and outflow tract endocardial cushion lineage-restricted periostin enhancer. Dev Biol 2007; 307:340-55. [PMID: 17540359 PMCID: PMC1995123 DOI: 10.1016/j.ydbio.2007.04.041] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 04/17/2007] [Accepted: 04/30/2007] [Indexed: 10/23/2022]
Abstract
Periostin is a fasciclin-containing adhesive glycoprotein that facilitates the migration and differentiation of cells that have undergone epithelial-mesenchymal transformation during embryogenesis and in pathological conditions. Despite the importance of post-transformational differentiation as a general developmental mechanism, little is known how periostin's embryonic expression is regulated. To help resolve this deficiency, a 3.9-kb periostin proximal promoter was isolated and shown to drive tissue-specific expression in the neural crest-derived Schwann cell lineage and in a subpopulation of periostin-expressing cells in the cardiac outflow tract endocardial cushions. In order to identify the enhancer and associated DNA binding factor(s) responsible, in vitro promoter dissection was undertaken in a Schwannoma line. Ultimately a 304-bp(peri) enhancer was identified and shown to be capable of recapitulating 3.9 kb(peri-lacZ)in vivo spatiotemporal patterns. Further mutational and EMSA analysis helped identify a minimal 37-bp region that is bound by the YY1 transcription factor. The 37-bp enhancer was subsequently shown to be essential for in vivo 3.9 kb(peri-lacZ) promoter activity. Taken together, these studies identify an evolutionary-conserved YY1-binding 37-bp region within a 304-bp periostin core enhancer that is capable of regulating simultaneous novel tissue-specific periostin expression in the cardiac outflow-tract cushion mesenchyme and Schwann cell lineages.
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Affiliation(s)
- Andrew Lindsley
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Paige Snider
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Hongming Zhou
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Rhonda Rogers
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Jian Wang
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Michael Olaopa
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
| | | | | | - Brenda Lilly
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia, GA 30912
| | - John B.E. Burch
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111
| | - Anthony B. Firulli
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Simon J. Conway.
- Cardiovascular Development Group, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202
- Address correspondence to: Simon J. Conway, Riley Hospital for Children, 1044 West Walnut Street, Room R4 W379, Indiana University School of Medicine, Indianapolis, IN 46202, USA. phone: (317) 278-8780; fax: (317) 278-5413; e-mail:
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16
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Aruga J, Yoshikawa F, Nozaki Y, Sakaki Y, Toyoda A, Furuichi T. An oligodendrocyte enhancer in a phylogenetically conserved intron region of the mammalian myelin gene Opalin. J Neurochem 2007; 102:1533-1547. [PMID: 17442045 DOI: 10.1111/j.1471-4159.2007.04583.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Opalin is a transmembrane protein detected specifically in mammalian oligodendrocytes. Opalin homologs are found only in mammals and not in the genome sequences of other animal classes. We first determined the nucleotide sequences of Opalin orthologs and their flanking regions derived from four prosimians, a group of primitive primates. A global comparison revealed that an evolutionarily conserved region exists in the first intron of Opalin. When the conserved domain was assayed for its enhancer activity in transgenic mice, oligodendrocyte-directed expression was observed. In an oligodendroglial cell line, Oli-neu, the conserved domain showed oligodendrocyte-directed expression. The conserved domain is composed of eight subdomains, some of which contain binding sites for Myt1 and cAMP-response element binding protein (CREB). Deletion analysis and cotransfection experiments revealed that the subdomains have critical roles in Opalin gene expression. Over-expression of Myt1, treatment of the cell with leukemia inhibitory factor (LIF), and cAMP analog (CREB activator) enhanced the expression of endogenous Opalin in Oli-neu cells and activated the oligodendrocyte enhancer. These results suggest that LIF, cAMP signaling cascades and Myt1 play significant roles in the differentiation of oligodendrocytes through their action on the Opalin oligodendrocyte enhancer.
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Affiliation(s)
- Jun Aruga
- Laboratory for Comparative Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanLaboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanSequence Technology Team, RIKEN Genomic Science Center, Yokohama, Japan
| | - Fumio Yoshikawa
- Laboratory for Comparative Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanLaboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanSequence Technology Team, RIKEN Genomic Science Center, Yokohama, Japan
| | - Yayoi Nozaki
- Laboratory for Comparative Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanLaboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanSequence Technology Team, RIKEN Genomic Science Center, Yokohama, Japan
| | - Yoshiyuki Sakaki
- Laboratory for Comparative Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanLaboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanSequence Technology Team, RIKEN Genomic Science Center, Yokohama, Japan
| | - Atsushi Toyoda
- Laboratory for Comparative Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanLaboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanSequence Technology Team, RIKEN Genomic Science Center, Yokohama, Japan
| | - Teiichi Furuichi
- Laboratory for Comparative Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanLaboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama, JapanSequence Technology Team, RIKEN Genomic Science Center, Yokohama, Japan
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17
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Bhat NR, Zhang P, Mohanty SB. p38 MAP kinase regulation of oligodendrocyte differentiation with CREB as a potential target. Neurochem Res 2007; 32:293-302. [PMID: 17235686 DOI: 10.1007/s11064-006-9274-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Accepted: 09/06/2006] [Indexed: 10/23/2022]
Abstract
Despite a substantial understanding of the factors regulating oligodendrocyte differentiation, the signaling mechanisms involved in this process are not well-understood. This study elaborates on the findings (Bhat NR, Zhang P (1997) FASEB J 11:A925; Baron W, Metz B, Bansal R, Hoekstra D, de Vries H (2000) Mol Cell Neurosci 15:314-329) of a role for p38 MAP kinase signaling in oligodendrocyte differentiation and myelin gene expression. When proliferating oligodendrocyte progenitors were switched to a growth factor-free differentiation medium, there was a rapid activation of p38 kinase that correlated with an increased phosphorylation of CREB, a down-stream target and a factor involved in oligodendrocyte differentiation. Addition of forskolin, a known inducer of intracellular c-AMP and of oligodendrocyte differentiation, also stimulated CREB phosphorylation in a p38 kinase dependent way. Pharmacological inhibition of p38 interfered with the morphological and antigenic changes associated with differentiating oligodendrocytes as well as with the developmental and forskolin-induced expression of myelin basic protein, thereby supporting an essential role for p38 MAPK pathway in oligodendrocyte differentiation.
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Affiliation(s)
- Narayan R Bhat
- Department of Neurosciences, Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC 29425, USA.
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18
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Füle T, Máthé M, Suba Z, Csapó Z, Szarvas T, Tátrai P, Paku S, Kovalszky I. The presence of human papillomavirus 16 in neural structures and vascular endothelial cells. Virology 2006; 348:289-96. [PMID: 16499942 DOI: 10.1016/j.virol.2005.12.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Revised: 11/17/2005] [Accepted: 12/01/2005] [Indexed: 11/16/2022]
Abstract
Human papillomavirus (HPV) is known as a strictly epitheliotropic pathogen. Our results raised the possibility that HPV 16 is present in neural cells and in the vascular endothelium. By in situ hybridization, we have detected HPV 16 E6 ORF sequence in small blood vessels and peripheral nerves adjacent to oral and cervical cancers. The same structures have clearly shown immunohistochemical reactivity for the E6 oncoprotein. These results were verified by PCR applied to E6 and L1 ORFs following microscopic laser dissection of the immunohistochemically positive nerves and vessels. These observations suggest that HPV 16 DNA and protein are present in neurons and endothelial cells in the vicinity of HPV-associated tumors. The HPV 16 genome presumably exists in a non-replicating form in the neurons and constitutively produces high levels of E6 and E7 proteins with an unknown neuropathological outcome.
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Affiliation(s)
- Tibor Füle
- Department of Molecular Pathology, Joint Research Organization of the Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
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19
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Campagnoni AT, Skoff RP. The pathobiology of myelin mutants reveal novel biological functions of the MBP and PLP genes. Brain Pathol 2006; 11:74-91. [PMID: 11145205 PMCID: PMC8098301 DOI: 10.1111/j.1750-3639.2001.tb00383.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Substantial biological data indicate that the myelin basic protein (MBP) and myelin proteolipid protein (PLP/DM20) genes produce products with functions beyond that of serving as myelin structural proteins. Much of this evidence comes from studies on naturally-occurring and man-made mutations of these genes in mice and other species. This review focuses upon recent evidence showing the existence of other products of these genes that may account for some of these other functions, and recent studies providing evidence for alternative biological functions of PLP/DM20. The MBP and PLP/DM20 genes each encode the classic MBP and PLP isoforms, as well as a second family of proteins that are not involved in myelin structure. The biological roles of these other products of the genes are becoming clarified. The non-classic MBP gene products appear to be components of transcriptional complexes in the nucleus, and they also may be involved in signaling pathways in T-cells and in neural cells. The non-classic PLP/DM20 gene products appear to be components of intracellular transport vesicles in oligodendrocytes. There is evidence for other functions of the classic PLP/DM20 proteins, including a role in neural cell death mechanisms, autocrine and paracrine regulation of oligodendrocytes and neurons, intracellular transport and oligodendrocyte migration.
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Affiliation(s)
- A T Campagnoni
- Neuropsychiatric Institute, UCLA School of Medicine, 90024, USA.
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20
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Boyle K, Azari MF, Cheema SS, Petratos S. TNFalpha mediates Schwann cell death by upregulating p75NTR expression without sustained activation of NFkappaB. Neurobiol Dis 2006; 20:412-27. [PMID: 15905096 DOI: 10.1016/j.nbd.2005.03.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 03/17/2005] [Accepted: 03/20/2005] [Indexed: 11/30/2022] Open
Abstract
Administration of tumour necrosis factor alpha (TNFalpha) to axotomised mouse neonatal sciatic nerves increased Schwann cell apoptosis in the distal nerve segments, 5-fold greater than axotomy alone. TNFalpha upregulated the low affinity neurotrophin receptor, p75NTR, indicative of phenotype reversion in Schwann cells. Furthermore, re-expression of p75NTR and downregulation of the pro-myelinating transcription factor, Oct 6, in Schwann cells occurred by treatment with TNFalpha, even after the maturation of these cells with brain derived neurotrophic factor (BDNF). TNFalpha treatment of Schwann cells produced only a transient activation of NFkappaB. More importantly, in NFkappaB (p65) mutant mice, axotomy increased Schwann cell apoptosis further than that seen in mice expressing NFkappaB (p65), implicating a survival role for NFkappaB. Collectively, these data suggest that TNFalpha can potentiate Schwann cell death through the modulation of their phenotype. Immature Schwann cells express a high level of p75NTR and as a consequence are susceptible to extracellular death stimuli because of the lack of sustained NFkappaB translocation.
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Affiliation(s)
- Kristy Boyle
- The Walter and Eliza Hall Institute of Medical Research, Department of Medical Biology, University of Melbourne, Post Office, The Royal Melbourne Hospital, Victoria 3050, Australia
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21
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Yaden BC, Garcia M, Smith TPL, Rhodes SJ. Two promoters mediate transcription from the human LHX3 gene: involvement of nuclear factor I and specificity protein 1. Endocrinology 2006; 147:324-37. [PMID: 16179410 DOI: 10.1210/en.2005-0970] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The LHX3 transcription factor is required for pituitary and nervous system development in mammals. Mutations in the human gene are associated with hormone-deficiency diseases. The gene generates two mRNAs, hLHX3a and hLHX3b, which encode three proteins with different properties. Here, the cis elements and trans-acting factors that regulate the basal transcription of the two mRNAs are characterized. A comparative approach was taken featuring analysis of seven mammalian Lhx3 genes, with a focus on the human gene. Two conserved, TATA-less, GC-rich promoters that are used to transcribe the mRNAs precede exons 1a and 1b of hLHX3. Transcription start sites were mapped for both promoters. Deletion experiments showed most activity for reporter genes containing the basal promoters in the context of -2.0 kb of hLHX3a and 1.8 kb of intron 1a (hLHX3b). Transfection, site-directed mutation, electrophoretic mobility shift, Southwestern blot, and chromatin immunoprecipitation approaches were used to characterize the interaction of transcription factors with conserved elements in the promoters. Specificity protein 1 is a regulator of both promoters through interaction with GC boxes. In addition, a distal element within intron 1a that is recognized by nuclear factor I is critical for hLHX3b promoter function. We conclude that dual promoters allow regulated production of two hLHX3 mRNAs.
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Affiliation(s)
- Benjamin C Yaden
- Department of Biology (B.C.Y., M.G.), Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
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22
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LeBlanc SE, Jang SW, Ward RM, Wrabetz L, Svaren J. Direct regulation of myelin protein zero expression by the Egr2 transactivator. J Biol Chem 2005; 281:5453-60. [PMID: 16373334 DOI: 10.1074/jbc.m512159200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
During myelination of the peripheral nervous system, the myelin protein zero (Mpz) gene is induced to produce the most abundant protein component (P(0)) of mature myelin. Although the basal embryonic expression of Mpz in Schwann cells has been attributed to regulation by Sox10, the molecular mechanism for the profound up-regulation of this gene during myelination has not been established. In this study, we have identified a highly conserved element within the first intron of the Mpz gene, which contains binding sites for the early growth response 2 (Egr2/Krox20) transcription factor, a critical regulator of peripheral nerve myelination. Egr2 can transactivate the intron element, and the induction is blocked by two known repressors of Egr2 activity. Using chromatin immunoprecipitation assays, we find that Egr2 binds in vivo to the intron element, but not to the Mpz promoter. Known inducers of Mpz expression such as forskolin and insulin-like growth factor-1 also activate the element in an Egr2-dependent manner. In addition, we found that Egr2 can act synergistically with Sox10 to activate this intron element, suggesting a model in which cooperative interactions between Egr2 and Sox10 mediate a large increase in Mpz expression to the high levels found in myelinating Schwann cells.
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Affiliation(s)
- Scott E LeBlanc
- Molecular and Cellular Pharmacology Program, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Drive, Madison, WI 53705, USA
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23
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Abstract
During the development of peripheral nerves, neural crest cells generate myelinating and non-myelinating glial cells in a process that parallels gliogenesis from the germinal layers of the CNS. Unlike central gliogenesis, neural crest development involves a protracted embryonic phase devoted to the generation of, first, the Schwann cell precursor and then the immature Schwann cell, a cell whose fate as a myelinating or non-myelinating cell has yet to be determined. Embryonic nerves therefore offer a particular opportunity to analyse the early steps of gliogenesis from transient multipotent stem cells, and to understand how this process is integrated with organogenesis of peripheral nerves.
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Affiliation(s)
- Kristjan R Jessen
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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24
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Leblanc SE, Srinivasan R, Ferri C, Mager GM, Gillian-Daniel AL, Wrabetz L, Svaren J. Regulation of cholesterol/lipid biosynthetic genes by Egr2/Krox20 during peripheral nerve myelination. J Neurochem 2005; 93:737-48. [PMID: 15836632 DOI: 10.1111/j.1471-4159.2005.03056.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Myelination of peripheral nerves by Schwann cells requires a large amount of lipid and cholesterol biosynthesis. To understand the transcriptional coordination of the myelination process, we have investigated the developmental relationship between early growth response 2 (Egr2)/Krox20--a pivotal regulator of peripheral nerve myelination--and the sterol regulatory element binding protein (SREBP) pathway, which controls expression of cholesterol/lipid biosynthetic genes. During myelination of sciatic nerve, there is a very significant induction of SREBP1 and SREBP2, as well as their target genes, suggesting that the SREBP transactivators are important regulators in the myelination process. Egr2/Krox20 does not appear to directly regulate the levels of SREBP pathway components, but rather, we found that Egr2/Krox20 and SREBP transactivators can synergistically activate promoters of several SREBP target genes, indicating that direct induction of cholesterol/lipid biosynthetic genes by Egr2/Krox20 is a part of the myelination program regulated by this transactivator.
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Affiliation(s)
- Scott E Leblanc
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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25
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Friedrich RP, Schlierf B, Tamm ER, Bösl MR, Wegner M. The class III POU domain protein Brn-1 can fully replace the related Oct-6 during schwann cell development and myelination. Mol Cell Biol 2005; 25:1821-9. [PMID: 15713637 PMCID: PMC549364 DOI: 10.1128/mcb.25.5.1821-1829.2005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Accepted: 11/20/2004] [Indexed: 11/20/2022] Open
Abstract
For differentiation, Schwann cells rely on the class III POU domain transcription factor Oct-6, which is expressed transiently when Schwann cells have established a one-to-one relation with axons but have not yet started to myelinate. Loss of Oct-6 leads to a transient arrest in this promyelinating stage and a delay in myelination. Although the closely related POU domain protein Brn-2 is coexpressed with Oct-6 in Schwann cells, its loss has only mild consequences. Combined loss of both POU domain proteins, in contrast, dramatically increases the myelination delay, raising the question of how related POU domain proteins compare to each other in their activities. Here, we have replaced Oct-6 expression in the mouse with expression of the class III POU domain protein Brn-1. Although this protein is not normally expressed in Schwann cells, Brn-1 was capable of fully replacing Oct-6. Brn-1 efficiently induced Krox-20 expression as a prerequisite for myelination. Onset and extent of myelination were also indistinguishable from that of the wild type in mice that carried only Brn-1 instead of Oct-6 alleles. Similar to Oct-6, Brn-1 down-regulated its own expression at later stages of myelination. Thus, class III POU domain proteins can fully replace each other in Schwann cell development.
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Affiliation(s)
- Ralf P Friedrich
- Institut für Biochemie, Universität Erlangen, Fahrstrasse 17, 91054 Erlangen, Germany
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26
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Fishbein L, Eady B, Sanek N, Muir D, Wallace MR. Analysis of somatic NF1 promoter methylation in plexiform neurofibromas and Schwann cells. ACTA ACUST UNITED AC 2005; 157:181-6. [PMID: 15721644 DOI: 10.1016/j.cancergencyto.2004.08.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Revised: 07/26/2004] [Accepted: 07/28/2004] [Indexed: 12/31/2022]
Abstract
Neurofibromatosis 1 (NF1) is an autosomal dominant disorder with the characteristic feature being the neurofibroma. It is believed that both NF1 alleles must be inactivated as the first step in tumorigenesis. However, often the somatic mutations are not identified, suggesting that epigenetic changes such as methylation could account for the "second hit" in some tumors. The literature reports that the region of the NF1 promoter surrounding the transcription start site is completely unmethylated in several normal tissues and some NF1-related dermal and plexiform neurofibromas. We analyzed the methylation state of the NF1 promoter in normal Schwann cells (the cell type clonally expanded in neurofibromas) and in NF1-related plexiform tumor samples with unidentified somatic mutations. In a region of 451 bp surrounding the transcription start site, a low level of methylation was found at several specific cytosines in 12 of 18 tumor samples. Overall, epigenetic silencing through methylation does not appear to be a major mechanism for the second hit. However, this study, which analyzed the largest number of NF1-related plexiform tumors and is the first to include Schwann cell-enriched tumor cultures, detected greater methylation than in any previous reports. This suggests that methylation, especially at potential transcription factor binding sites, is moderately perturbed in some plexiform neurofibromas and should be investigated further.
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Affiliation(s)
- Lauren Fishbein
- Department of Molecular Genetics and Microbiology, University of Florida, 1600 SW Archer Road, ARB R2-220, P.O. Box 100266, Gainesville, FL 32610-0266, USA
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27
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Tencomnao T, Kapitonov D, Bieberich E, Yu RK. Transcriptional regulation of the human UDP-galactose:ceramide galactosyltransferase (hCGT) gene expression: functional role of GC-box and CRE. Glycoconj J 2005; 20:339-51. [PMID: 15229398 DOI: 10.1023/b:glyc.0000033630.58533.16] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
UDP-galactose:ceramide galactosyltransferase (CGT, EC 2.4.1.45) is a key enzyme in the biosynthetic pathway of galactocerebroside (GalC), the most abundant glycolipid in myelin. Using a GalC expressing cell line, human oligodendroglioma (HOG), one which does not express GalC, human neuroblastoma (LAN-5), we previously demonstrated that the human CGT (hCGT) gene promoter functions in a cell-specific manner. Because the proximal (-292/-256) and distal (-747/-688) positive domains were shown to be critically involved in regulating the expression of several myelin-specific genes, we further investigated the functional roles of these two motifs in hCGT expression. Mutation analysis confirmed that a GC-box (-267/-259) and a CRE (-697/-690) were critical for hCGT expression. Electrophoretic mobility shift assay (EMSA) demonstrated that these motifs specifically bound to nuclear extracts from both cell lines. Using antibodies to Sp1, Sp3, pCREB-1, and ATF-1, these proteins were shown to be components of the EMSA complexes. However, the only difference between the HOG and LAN-5 cells was found in the EMSA profile of the CRE complexes. This difference may account for the differential transcription of the hCGT gene in the two cell types. Furthermore, the expression levels of ATF-1 detected were much higher in HOG cells than in LAN-5 cells. Thus, our data suggest that the GC-box and CRE function cooperatively, and that the CRE regulates the cell-specific expression of the hCGT gene.
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Affiliation(s)
- Tewin Tencomnao
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912-2697, USA
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28
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Wei Q, Miskimins WK, Miskimins R. Stage-specific expression of myelin basic protein in oligodendrocytes involves Nkx2.2-mediated repression that is relieved by the Sp1 transcription factor. J Biol Chem 2005; 280:16284-94. [PMID: 15695521 DOI: 10.1074/jbc.m500491200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The homeodomain-containing protein Nkx2.2 is critical for the development of oligodendrocyte lineage cells, but the target genes of Nkx2.2 regulation have not been identified. In the present study, we found that the myelin basic protein gene is one of the genes that is regulated by Nkx2.2. Expression of Nkx2.2 represses the expression of myelin basic protein in oligodendrocyte progenitors. Two regulatory elements in the myelin basic protein promoter were identified and found to interact with Nkx2.2 in vitro. Despite their sequence divergence, both sites were involved in the Nkx2.2-mediated repression of the myelin basic protein promoter. Binding of Nkx2.2 also blocked and disrupted the binding of the transcriptional activator Puralpha to the myelin basic protein promoter. Additionally Nkx2.2 recruited a histone deacetylase 1-mSin3A complex to the myelin basic protein promoter. We also found that the transcription factor Sp1 was able to compete off the binding of Nkx2.2 to its consensus binding site in vitro and reversed the repressive effect of Nkx2.2 in vivo. Our data revealed a novel role for Nkx2.2 in preventing the precocious expression of myelin basic protein in immature oligodendrocytes. Based on this study and our previous reports, a model for myelin basic protein gene control is proposed.
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Affiliation(s)
- Qiou Wei
- Division of Basic Biomedical Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069, USA
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29
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Maier M, Castagner F, Berger P, Suter U. Distinct elements of the peripheral myelin protein 22 (PMP22) promoter regulate expression in Schwann cells and sensory neurons. Mol Cell Neurosci 2003; 24:803-17. [PMID: 14664827 DOI: 10.1016/s1044-7431(03)00246-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genetic disease mechanisms in the demyelinating peripheral neuropathies Charcot-Marie-Tooth disease type 1A (CMTA) and hereditary neuropathy with liability to pressure palsies (HNPP) as well as transgenic animals with altered PMP22 gene dosage revealed that alterations in PMP22 gene expression have profound effects on the development and maintenance of peripheral nerves. Consequently, the regulation of PMP22 is a crucial aspect in understanding the function of this protein in health and disease. In this study, we dissected and analyzed different cis-acting elements in the 5'-flanking region of the Pmp22 gene in vivo. We found two separate elements that contribute to different aspects of Pmp22 expression. The first is located 5' distally to promoter 1 and is involved in gene regulation during late phases of myelination in development ["late myelination Schwann cell-specific element" (LMSE)] and in remyelination after injury. The second element was identified upstream of promoter 2 and guides Pmp22 expression in sensory neurons. These results suggest that multiple distinct signaling pathways regulating Pmp22 expression in myelination as well as in neurons converge on distinct segments of the PMP22 promoter region. The underlying molecular mechanisms are likely to be crucially involved in the maintenance of the integrity of myelinated peripheral nerves.
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Affiliation(s)
- Marcel Maier
- Institute of Cell Biology, Department of Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zurich, Switzerland
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30
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Vourc'h P, Dessay S, Mbarek O, Marouillat Védrine S, Müh JP, Andres C. The oligodendrocyte-myelin glycoprotein gene is highly expressed during the late stages of myelination in the rat central nervous system. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 144:159-68. [PMID: 12935913 DOI: 10.1016/s0165-3806(03)00167-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Oligodendrocyte-myelin glycoprotein (OMgp) is expressed on the surface of oligodendrocytes and neurones and is thought to inhibit axonal regeneration after brain injury in adult, like Nogo and myelin-associated glycoprotein (MAG). We previously observed that the OMgp gene locus on chromosome 17 could be associated with autism, a developmental disorder. The aim of the present study was to characterise the developmental expression of OMgp mRNA in the central nervous system. First we determined the rat OMgp gene sequence and compared it with the human and mouse sequences. Several regions, putative sites for the fixation of transcription factors, are conserved between these three species in the unique intron of this gene. Using quantitative and semi-quantitative RT-PCR, we studied OMgp gene expression in rat brain during post-natal development. We found that OMgp mRNA expression was developmentally regulated, with a peak of expression in the late stages of myelination. We observed a similar profile in oligodendrocyte cultures, in absence of neurones, suggesting that OMgp mRNA expression by oligodendrocytes was independent of axonal influence. Our observations suggest that OMgp is a late marker of myelination, which could be implicated in the arrest of oligodendrocyte proliferation, arrest of myelination or compaction of myelin.
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Affiliation(s)
- Patrick Vourc'h
- Génétique de l'autisme et de la déficience mentale, INSERM U 316, 2 bis, Boulevard Tonnellé, 37032 Tours Cedex, France
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Wei Q, Miskimins WK, Miskimins R. Cloning and characterization of the rat myelin basic protein gene promoter. Gene 2003; 313:161-7. [PMID: 12957387 DOI: 10.1016/s0378-1119(03)00675-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Expression of myelin basic protein in differentiating oligodendrocytes is mainly regulated at the transcriptional level. To better understand the regulation of myelin basic protein gene expression in mammalian cells, we cloned and characterized the rat myelin basic protein promoter by a genome walking technique. Extensive sequence homology has been found among mouse, rat and human MBP promoters. Alignment of the proximal core promoter of mouse and rat reveals highly conserved cis-elements that are important for regulating myelin basic protein gene transcription. One major transcription start site along with two minor sites have been identified in both mouse and rat myelin basic protein gene promoters using RNA ligase-mediated rapid amplification of 5' cDNA ends. The amplified rat myelin basic protein promoter was cloned into a luciferase reporter construct. Transient transfection experiments show that both mouse and rat myelin basic protein promoters yield increased expression when oligodendrocytes differentiate. The sequence and characterization of the rat MBP promoter provide a useful tool to investigate MBP gene regulation in mammalian cells.
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Affiliation(s)
- Qiou Wei
- Division of Basic Biomedical Sciences, University of South Dakota School of Medicine, Vermillion, SD 57069, USA
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Abstract
We have used lactacystin, a specific inhibitor of the 26S proteasome, in oligodendroglial cell (OLGc) primary cultures to explore the possible participation of the proteasome-ubiquitin-dependent pathway in the decision of the OLGcs to arrest their proliferation and start differentiation. Addition of lactacystin at various concentrations to cultures containing a majority of OLGc was found to produce their withdrawal from the cell cycle and to induce their biochemical and morphological differentiation, with the appearance of extensive myelin-like sheets. The three classic proteolytic activities of the proteasome were significantly decreased in the lactacystin-treated cultures, and the immunocytochemical analysis showed an increase in the number of O4-, O1-, myelin basic protein-, and myelin proteolipid protein-positive cells and a decrease in A2B5-reacting cells. Quantitative immunochemical evaluation of the expression of certain proteins controlling the cell cycle showed an increase in p27kip1-, cyclin D-, and cdk4-positive cells, with a decrease in cyclin E- and cdk2-positive cells. In the lactacystin-treated OLGcs, there was a dose-dependent decrease in the number of cells incorporating bromodeoxyuridine and in the activity of the complexes cyclin D-cdk4 and cyclin E-cdk2. Furthermore, increased levels of expression of several STAT factors were found, suggesting that proteasome inhibition in OLGcs could stabilize signals of survival and differentiation that might be processed through the JAK/STAT signaling cascade.
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Roth AD, Leisewitz AV, Jung JE, Cassina P, Barbeito L, Inestrosa NC, Bronfman M. PPAR gamma activators induce growth arrest and process extension in B12 oligodendrocyte-like cells and terminal differentiation of cultured oligodendrocytes. J Neurosci Res 2003; 72:425-35. [PMID: 12704804 DOI: 10.1002/jnr.10596] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are key transcription factors in the control of lipid homeostasis and cell differentiation, but little is known about their function in oligodendrocytes, the major lipid-synthesizing cells in the central nervous system (CNS). Using the B12 oligodendrocyte-like cell line and rat spinal cord-derived oligodendrocytes, we evaluated the importance of PPARgamma in the maturation process of these cells. B12 cells express all PPAR isoforms (alpha, beta/delta, and gamma), as assessed by RT-PCR, Western-blot, and transactivation assays. B12 cells respond specifically to PPARgamma agonists by arresting cell proliferation and extending cell processes, events that are blocked by the PPARgamma antagonist GW9662. In addition, alkyl-dihydroxyacetone phosphate synthase (ADAPS), a key peroxisomal enzyme involved in the synthesis of myelin-rich lipid plasmalogens, is increased in PPARgamma agonist-treated B12 cells. In contrast with B12 cells, both immature and mature isolated spinal cord oligodendrocytes presented a high and similar expression level of ADAPS, as assessed by immunocytochemistry. However, as in B12 cells, isolated spinal cord oligodendrocytes were also found to respond specifically to PPARgamma agonists with a four-fold increase in the number of mature cells. Our data suggest a relevant role for PPARgamma in oligodendrocyte lipid metabolism and differentiation.
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Affiliation(s)
- Alejandro D Roth
- Centro de Regulación Celular y Patología, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
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Abstract
Oligodendrocytes, myelin-forming glial cells of the central nervous system, are vulnerable to damage in a variety of neurologic diseases. Much is known of primary myelin injury, which occurs in settings of genetic dysmyelination or demyelinating disease. There is growing awareness that oligodendrocytes are also targets of injury in acute ischemia. Recognition of oligodendrocyte damage in animal models of ischemia requires attention to their distinct histologic features or use of specific immunocytochemical markers. Like neurons, oligodendrocytes are highly sensitive to injury by oxidative stress, excitatory amino acids, trophic factor deprivation, and activation of apoptotic pathways. Understanding mechanisms of oligodendrocyte death may suggest new therapeutic strategies to preserve or restore white matter function and structure after ischemic insults.
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Affiliation(s)
- Deborah Dewar
- Division of Clinical Neuroscience, University of Glasgow, Wellcome Surgical Institute, Garscube Estate, Bearsden Road, Glasgow C61 1QH, Scotland, UK.
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Oertle T, Huber C, van der Putten H, Schwab ME. Genomic structure and functional characterisation of the promoters of human and mouse nogo/rtn4. J Mol Biol 2003; 325:299-323. [PMID: 12488097 DOI: 10.1016/s0022-2836(02)01179-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The reticulon-family member Nogo-A is a potent neurite growth inhibitory protein in vitro and may play a role in the restriction of axonal regeneration after injury and of structural plasticity in the CNS of higher vertebrates. Of the three major isoforms of Nogo, Nogo-A is mostly expressed in the brain, Nogo-B is found in a ubiquitous pattern, and Nogo-C is most highly expressed in muscle. Seven additional splice-variants derived both from differential splicing and differential promoter usage have been identified. Analysis of the TATA-less Nogo-A/B promoter (P1) shows that conserved GC-boxes and a CCAAT-box within the first 500bp upstream of the transcription start are responsible for its regulation. No major differences in the methylation status of the P1 CpG-island in tissues expressing or not expressing Nogo-A/B could be detected, suggesting that silencer elements are involved in the regulation. The specific expression pattern of Nogo-A/B is due to differential splicing. The basal Nogo-C promoter (P2) is regulated by a proximal and a distal element. The 5'UTR of Nogo-C harbours a negative control element. These data may help to identify factors that can modulate Nogo transcription, thus offering an alternative approach for Nogo neutralisation.
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Affiliation(s)
- Thomas Oertle
- Brain Research Institute, University of Zurich and Department of Biology, Swiss Federal Institute of Technology, Switzerland.
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Szuchet S, Seeger MA. Oligodendrocyte phenotypical and morphological heterogeneity: a reexamination of old concepts in view of new findings. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1569-2558(03)31002-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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Ghazvini M, Mandemakers W, Jaegle M, Piirsoo M, Driegen S, Koutsourakis M, Smit X, Grosveld F, Meijer D. A cell type-specific allele of the POU gene Oct-6 reveals Schwann cell autonomous function in nerve development and regeneration. EMBO J 2002; 21:4612-20. [PMID: 12198163 PMCID: PMC125415 DOI: 10.1093/emboj/cdf475] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
While an important role for the POU domain transcription factor Oct-6 in the developing peripheral nerve has been well established, studies into its exact role in nerve development and regeneration have been hampered by the high mortality rate of newborn Oct-6 mutant animals. In this study we have generated a Schwann cell-specific Oct-6 allele through deletion of the Schwann cell-specific enhancer element (SCE) in the Oct-6 locus. Analysis of mice homozygous for this allele (deltaSCE allele) reveals that rate-limiting levels of Oct-6 in Schwann cells are dependent on the SCE and that this element does not contribute to Oct-6 regulation in other cell types. We demonstrate a Schwann cell autonomous function for Oct-6 during nerve development as well as in regenerating nerve. Additionally, we show that Krox-20, an important regulatory target of Oct-6 in Schwann cells, is activated, with delayed kinetics, through an Oct-6-independent mechanism in these mice.
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Affiliation(s)
- Merhnaz Ghazvini
- Department of Cell Biology and Genetics, Erasmus University Rotterdam, PO Box 1738, 3000DR Rotterdam, The Netherlands
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Reyes SD, Campagnoni AT. Two separate domains in the golli myelin basic proteins are responsible for nuclear targeting and process extension in transfected cells. J Neurosci Res 2002; 69:587-96. [PMID: 12210824 DOI: 10.1002/jnr.10319] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The golli products of the myelin basic protein (MBP) gene are expressed in neurons and oligodendrocytes (OLs). In certain neuronal populations, golli proteins undergo translocation between the nucleus and cytoplasm/processes during development. The proteins consist of two domains, a golli domain of 133 amino acids and an MBP domain of variable length. One objective of this study was to identify the sequences responsible for nuclear targeting. Site-directed mutagenesis and deletion analyses were used to generate a series of golli-green fluorescent protein (GFP) DNA constructs that were transfected into OL and neuronal cell lines to follow localization by confocal microscopy. The results indicated that a 36-residue stretch in the MBP domain is essential for nuclear targeting, and the sequence appears to be a nontraditional localization signal motif. The studies also revealed that overexpression of golli proteins could induce dramatic changes in cell morphology. In OL lines, overexpression of intact golli proteins, or golli peptide alone, caused an increase in the length and number of processes, and the elaboration of membrane sheets. In the neuronal lines, there was a dramatic increase in number and length of extensions. The results, consistent with the timing of golli expression in cells during neural development, suggest that golli proteins may be involved in process formation/extension in OLs and neurons during development. These studies have defined two functional domains in the golli protein. Sequences in the MBP domain target the protein into the nucleus and sequences within the golli domain induce process sheet extension in OLs and neurons.
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Affiliation(s)
- Samuel D Reyes
- Developmental Biology Group, Neuropsychiatric Institute, University of California, Los Angeles, School of Medicine, Los Angeles, California, USA
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40
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Abstract
Schwann cells are the major glial population of the vertebrate peripheral nervous system. In the adult, they build a protecting sheath around neuronal processes and myelinate large-caliber axons. Already early in development, Schwann cells and neurons establish close contacts. Later development and the maintenance of peripheral nerves are crucially dependent on the controlled bi-directional dialogue between these two cell types. Several major phases can be distinguished in the life of a Schwann cell: determination, differentiation, and potentially myelination. The aim of this review is to summarize the molecular and cellular characteristics of the first steps in the life of a Schwann cell, the development from a multipotent neural crest cell to a differentiated Schwann cell.
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Affiliation(s)
- Christian S Lobsiger
- Institute of Cell Biology, Department of Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, Zurich
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Afshari FS, Chu AK, Sato-Bigbee C. Recovery of adult oligodendrocytes is preceded by a "lag period" accompanied by upregulation of transcription factors expressed in developing young cells. J Neurosci Res 2002; 67:174-84. [PMID: 11782961 DOI: 10.1002/jnr.10091] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cell cultures prepared from oligodendrocytes directly obtained from adult rat brain are composed of mature cells that lose their cell processes and myelin membrane during their isolation and therefore represent a very useful model to investigate the factors that could stimulate their recovery. We have observed that mature oligodendrocytes isolated from adult animals remain as round cells that lack processes for the first 3-4 days in culture. At the end of this lag period, however, the majority of the adult oligodendrocytes show a remarkable recovery, rapidly growing complex and extensive cell processes. Interestingly, the end of this lag period is accompanied by a dramatic upregulation in the expression of thyroid hormone (T(3)) receptor (TR). The functional importance of this increase in TR levels is supported by the observation that the majority of the cells cultured in the presence of T(3) show significantly more extensive and complex process outgrowth than the control cells in cultures lacking this hormone. In addition, this reactivation of the adult cells was also preceded by an increased expression of glucocorticoid receptor (GR) and cyclic AMP-response element binding protein (CREB), two transcription factors that together with TR appear to play important roles in the control of neonatal oligodendrocyte development. Thus, it is possible to hypothesize that upregulation of these proteins may be part of the metabolic changes that occur during the lag period required for recovery of the adult oligodendrocytes. These observations raise the question of whether these transcription factors may play any significant role during remyelination after demyelinating lesions of adult CNS.
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Affiliation(s)
- Fatemah S Afshari
- Department of Biochemistry and Molecular Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298-0614, USA
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42
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Mercier G, Turque N, Schumacher M. Early activation of transcription factor expression in Schwann cells by progesterone. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 97:137-48. [PMID: 11750070 DOI: 10.1016/s0169-328x(01)00311-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Progesterone (PROG) promotes the myelination of sciatic nerves during regeneration after cryolesion. But, little is known about the molecular mechanisms by which the hormone exerts its effects. This could be initiated by the regulation of transcription factor expression in Schwann cells, which produce the myelin sheaths in the peripheral nervous system. We investigated by RT-PCR whether PROG activated expression of transcription factors: Egr-1 (Krox-24) Egr-2 (Krox-20), Egr-3, c-jun, jun B, jun D, c-Fos, Fos B, Fra-1, Fra-2, CREB, ATF 4, SCIP and Sox-10 in cultured Schwann cells. PROG triggered a quick (visible as soon as 15 min), strong (6 to 18-fold) and transient (1-2 h) stimulation of Egr-1, Egr-2, Egr-3 and Fos B genes expression. Expression of other genes remained unaffected by PROG treatment. The same expression pattern was obtained in the MSC 80 line (mouse Schwann cells), but not in the NIH-3T3 and CHO lines. Estradiol and testosterone induced different patterns of transcription factor gene activation in Schwann cells. Serum stimulated all genes activated by PROG in addition c-fos, fra-1 and fra-2. The PROG effects were blocked by Actinomycin D and by RU 486. This suggests that the activation of these genes occurs at the transcriptional level via the interaction of the hormone with its cognate receptor. Thus, PROG can regulate Schwann cell functions and differentiation by transiently activating specific transcription factors.
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Affiliation(s)
- G Mercier
- U 488 Inserm, 80 rue du Général Leclerc, 94276 Kremlin-Bicêtre, France.
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43
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Paratore C, Goerich DE, Suter U, Wegner M, Sommer L. Survival and glial fate acquisition of neural crest cells are regulated by an interplay between the transcription factor Sox10 and extrinsic combinatorial signaling. Development 2001; 128:3949-61. [PMID: 11641219 DOI: 10.1242/dev.128.20.3949] [Citation(s) in RCA: 243] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The transcription factor Sox10 is required for proper development of various neural crest-derived cell types. Several lineages including melanocytes, autonomic and enteric neurons, and all subtypes of peripheral glia are missing in mice homozygous for Sox10 mutations. Moreover, haploinsufficiency of Sox10 results in neural crest defects that cause Waardenburg/Hirschsprung disease in humans. We provide evidence that the cellular basis to these phenotypes is likely to be a requirement for Sox10 by neural crest stem cells before lineage segregation. Cell death is increased in undifferentiated, postmigratory neural crest cells that lack Sox10, suggesting a role of Sox10 in the survival of neural crest cells. This function is mediated by neuregulin, which acts as a survival signal for postmigratory neural crest cells in a Sox10-dependent manner. Furthermore, Sox10 is required for glial fate acquisition, as the surviving mutant neural crest cells are unable to adopt a glial fate when challenged with different gliogenic conditions. In Sox10 heterozygous mutant neural crest cells, survival appears to be normal, while fate specifications are drastically affected. Thereby, the fate chosen by a mutant neural crest cell is context dependent. Our data indicate that combinatorial signaling by Sox10, extracellular factors such as neuregulin 1, and local cell-cell interactions is involved in fine-tuning lineage decisions by neural crest stem cells. Failures in fate decision processes might thus contribute to the etiology of Waardenburg/Hirschsprung disease.
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Affiliation(s)
- C Paratore
- Institute of Cell Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zurich, Switzerland
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Tanaka K, Nogawa S, Ito D, Suzuki S, Dembo T, Kosakai A, Fukuuchi Y. Phosphorylation of cyclic adenosine monophosphate response element binding protein in oligodendrocytes in the corpus callosum after focal cerebral ischemia in the rat. J Cereb Blood Flow Metab 2001; 21:1177-88. [PMID: 11598495 DOI: 10.1097/00004647-200110000-00006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Phosphorylation of cyclic adenosine monophosphate (AMP) response element binding protein (CREB) was examined immunohistochemically in the corpus callosum of the rat brain at various time points after 90-minute focal cerebral ischemia. Focal ischemia was induced by occlusion of the middle cerebral artery (MCA) using the intraluminal suture method. Sham animals showed that numerous oligodendrocytes (OLGs) constitutively express unphosphorylated CREB. Local cerebral blood flow (lCBF) measured by the 14C-iodoantipyrine method was reduced from 44.2 +/- 15.4 (mL 100 g(-1) min(-1)) to 18.4 +/- 3.8 and from 53.9 +/- 14.4 to 4.8 +/- 4.5 in the medial and the lateral regions of the corpus callosum, respectively, during MCA occlusion (MCAO). After release of the MCAO, lCBF recovered to the control level in each region. The medial region of the corpus callosum showed a marked increase in phosphorylated CREB-positive OLGs at 3.5 hours of recirculation, and it remained increased until 2 weeks of recirculation as it gradually declined. The activation of CREB phosphorylation in the OLGs was accompanied by expression of antiapoptotic protein bcl-2, normal staining with cresyl violet, and negative TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling) staining. Myelination detected by immunostaining with anti-myelin basic protein (MBP) antibody and anti-myelin associated glycoprotein (MAG) antibody remained normal in the medial region of the corpus callosum. The lateral region of the corpus callosum showed a significant but only transient increase in phosphorylated CREB-positive OLGs at 3.5 hours of recirculation, which was followed by a rapid decrease during the subsequent recirculation period. Expression of bcl-2 was suppressed in this region, and demyelination became apparent. These findings suggest that signal transduction through CREB phosphorylation may be closely associated with survival of OLGs and maintenance of myelination in the corpus callosum after cerebral ischemia.
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Affiliation(s)
- K Tanaka
- Department of Neurology, School of Medicine, Keio University, Tokyo, Japan
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Hai M, Bidichandani SI, Patel PI. Identification of a positive regulatory element in the myelin-specific promoter of the PMP22 gene. J Neurosci Res 2001; 65:508-19. [PMID: 11550219 DOI: 10.1002/jnr.1181] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Over- and under expression of the 22 kDa peripheral myelin protein (PMP22) results in dysmyelinating peripheral neuropathies, such as Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy, with the liability to pressure palsies (HNPP). Expression of the PMP22 gene is driven by two alternative promoters, P1 and P2, with transcripts originating from P1 associated with peripheral nerve myelination by Schwann cells. Transient transfections of constructs containing P1 (3.5 kb) or P2 (2.5 kb) resulted in high levels of reporter gene expression in the RT4-D6P2T schwannoma cell line. Serial deletions of P1 revealed that region P1-A (-105 to -43), situated upstream of the minimal promoter, contained a positive regulatory element. The 62 bp P1-A region conferred in cis a sevenfold increase in expression of luciferase driven by a heterologous promoter in an orientation-dependent manner. Interspecies comparison of the P1-A region revealed a 98% degree of identity between the human, mouse, and rat sequences. A prominent sequence-dependent DNA-protein complex (C-I) was detected in electrophoretic mobility shift assays with P1-A using RT4-D6P2T nuclear extract and was localized to a minimal 21 bp region within P1-A. Site-directed mutagenesis of this region revealed nucleotides at positions -46 to -43 as being necessary for formation of C-I. Functional analysis of the mutated P1-A element indicated that positions -46 and -45 were essential for transactivation mediated by this element. Characterization of the transacting factor(s) interacting with this key regulatory element will shed light on its role in regulating peripheral nerve myelination.
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Affiliation(s)
- M Hai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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Bichenkov E, Ellingson JS. Ethanol exerts different effects on myelin basic protein and 2',3'-cyclic nucleotide 3'-phosphodiesterase expression in differentiating CG-4 oligodendrocytes. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2001; 128:9-16. [PMID: 11356257 DOI: 10.1016/s0165-3806(01)00142-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Evidence suggests that abnormal myelination is one factor contributing to the neuoropathology associated with fetal alcohol syndrome. We investigated the potential teratogenic effects of ethanol (EtOH) on myelin formation by determining its effects on the developmentally regulated increased expression of myelin basic protein (MBP) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in differentiating CG-4 oligodendrocytes (OLGs). By using CG-4 OLGs in vitro we identified processes altered by ethanol actions exerted directly on OLGs. During the first 8 days of development, EtOH decreased the expression of the major structural 18.5 and 14 kDa MBP isoforms by at least 40% at 4 days of development. EtOH concentrations between 25 and 75 mM inhibited MBP expression in a dose-dependent manner. Adding or withdrawing EtOH on specific days of differentiation reversibly modulated the expression of MBP, and the degree of inhibition was directly related to the length of ethanol exposure. As little as two consecutive days of EtOH exposure either early or late during development caused at least a 20% inhibition, however, no short critical time window of EtOH vulnerability for the inhibition was observed. The ethanol effect was selective for MBP expression, as EtOH did not alter the developmentally-regulated increased expression of CNP isozymes or enzyme activity. The results indicate that one factor contributing to the development of fetal alcohol syndrome may be defective myelination resulting from delayed and decreased MBP expression.
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Affiliation(s)
- E Bichenkov
- Department of Pathology, Anatomy, and Cell Biology, Medical College of Thomas Jefferson University, 269 Jefferson Alumni Hall, 1020 Locust Street, Philadelphia, PA 19107, USA
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Berndt JA, Kim JG, Tosic M, Kim C, Hudson LD. The transcriptional regulator Yin Yang 1 activates the myelin PLP gene. J Neurochem 2001; 77:935-42. [PMID: 11331422 DOI: 10.1046/j.1471-4159.2001.00307.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Inauguration of the myelin program in developing oligodendrocytes requires the activation of those genes that encode the myelin proteins and the enzymes responsible for the synthesis and degradation of myelin lipids. An activator of the most abundantly expressed myelin protein, proteolipid protein (PLP), has been identified in a yeast one-hybrid system. The ubiquitously expressed zinc finger protein Yin Yang 1 (YY1) recognizes the myelin PLP promoter in vitro and in vivo. When overexpressed in an oligodendrocyte cell line, YY1 enhances transcription of the PLP promoter. A truncated version of YY1 that includes only the four zinc finger domains has little effect. The binding site for YY1 in the PLP promoter (site 3) fits the YY1 consensus site and DNA-protein complexes containing site 3 can be supershifted with an antibody directed against YY1 protein. Moreover, oligonucleotides with a mutated version of the PLP promoter site 3 are unable to bind to nuclear proteins or to compete for binding in a gel shift system. Finally, mutation of this site greatly reduces the activity of a 1-kb PLP promoter region in transfected glial cells. Our results suggest that PLP is a target gene for the transcriptional regulator YY1. This versatile transcription factor and nuclear matrix protein may boost transcription of the PLP gene to meet the demands of actively myelinating oligodendrocytes.
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Affiliation(s)
- J A Berndt
- Laboratory of Developmental Neurogenetics, National Institute of Neurologic Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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Tencomnao T, Yu RK, Kapitonov D. Characterization of the human UDP-galactose:ceramide galactosyltransferase gene promoter. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1517:416-23. [PMID: 11342220 DOI: 10.1016/s0167-4781(00)00283-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
UDP-galactose:ceramide galactosyltransferase (CGT, EC 2.4.1.45) is a key enzyme in the biosynthesis of galactocerebroside, the most abundant glycosphingolipid in the myelin sheath. An 8 kb fragment upstream from the transcription initiation site of CGT gene was isolated from a human genomic DNA library. Primer extension analysis revealed a single transcription initiation site 329 bp upstream from the ATG start codon. Neither a consensus TATA nor a CCAAT box was identified in the proximity to the transcription start site; however, this region contains a high GC content and multiple putative regulatory elements. To investigate the transcriptional regulation of CGT, a series of 5' deletion constructs of the 5'-flanking region were generated and cloned upstream from the luciferase reporter gene. By comparing promoter activity in the human oligodendroglioma (HOG) and human neuroblastoma (LAN-5) cell lines, we found that the CGT promoter functions in a cell type-specific manner. Three positive cis-acting regulatory regions were identified, including a proximal region at -292/-256 which contains the potential binding sites for known transcription factors (TFs) such as Ets and SP1 (GC box), a distal region at -747/-688 comprising a number of binding sites such as the ERE half-site, NF1-like, TGGCA-BP, and CRE, and a third positive cis-acting region distally localized at -1325/-1083 consisting of binding sites for TFs such as nitrogen regulatory, TCF-1, TGGCA-BP, NF-IL6, CF1, bHLH, NF1-like, GATA, and gamma-IRE. A negative cis-acting domain localized in a far distal region at -1594/-1326 was also identified. Our results suggest the presence of both positive and negative cis-regulatory regions essential for the cell-specific expression in the TATA-less promoter of the human CGT gene.
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Affiliation(s)
- T Tencomnao
- Department of Biochemistry and Molecular Biophysics, Medical College of Virginia Commonwealth University, Richmond 23298-0614, USA
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