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Adhesion Molecule Profile and the Effect of Anti-VLA-4 mAb Treatment in Experimental Autoimmune Encephalomyelitis, a Mouse Model of Multiple Sclerosis. Int J Mol Sci 2022; 23:ijms23094637. [PMID: 35563027 PMCID: PMC9101715 DOI: 10.3390/ijms23094637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 11/22/2022] Open
Abstract
In the course of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), the infiltration of lymphocytes and other inflammatory cells across the blood–brain barrier is associated with interactions between adhesion molecules expressed by infiltrating cells and vascular endothelium. Monoclonal antibodies (mAb) against the α4 subunit of α4-β1 integrin (VLA-4) show beneficial effects in both MS and EAE. (1) Background: The aim of this study was to examine the expression of selected adhesion molecules: VLA-4, VCAM-1, LFA-1, ICAM-1 and PECAM-1 in the successive phases of EAE and the effect of anti-VLA-4 mAb treatment on that expression. (2) Methods: EAE was induced in C57BL/6 mice by immunization with MOG35–55 peptide. The animals were killed in three successive phases of the disease: onset (day 13), peak (day 18) and chronic (day 28). Frozen sections of the lumbar spinal cord were examined by quantitative immunofluorescence microscopy. The expression of the studied molecules was quantified as the percentage of the cross-sectioned spinal cord lesion area occupied by immunopositive structures. (3) Results: The expression of the studied molecules showed two temporal patterns: (1) an increase in the onset phase, a maximum in the peak phase and a decrease in the chronic phase, which corresponded to the temporal pattern of the clinical score, the number of lesions and the inflammation level (ICAM-1, LFA-1 and PECAM-1), and (2) an increase in the peak phase and no significant change or further increase in the chronic phase (VCAM-1, VLA-4). Among the molecules studied, ICAM-1 and LFA-1 exhibited the highest expression levels in the peak phase of EAE. Anti-VLA-4 mAb inhibited the expression of not only VLA-4 but also other adhesion molecules. (4) Conclusions: The interactions of adhesion molecules governing the migration of leukocytes across the blood–brain barrier change in the successive phases of EAE. The therapeutic mechanism of anti-VLA-4 mAb treatment seems to include a complex influence on a variety of adhesion molecules expressed by infiltrating cells and vascular endothelium.
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Chawla R, Nath M, Moksha L, Nag TC, Velpandian T. An experimental study to evaluate safety/toxicity of intravitreal natalizumab. Indian J Ophthalmol 2018; 66:1441-1445. [PMID: 30249830 PMCID: PMC6173036 DOI: 10.4103/ijo.ijo_425_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Purpose: The purpose of this prospective experimental study was to evaluate the safety/toxicity of α4β1 integrin blockade in rabbit retina using its monoclonal antibody (Natalizumab). Methods: Twelve New Zealand albino rabbits were divided into three groups (n = 4). Unilateral intravitreal injections of three different concentrations of natalizumab were performed in every rabbit of each group (Group A: 0.625 mg, Group B: 1.25 mg, and Group C: 2.5 mg). Baseline electroretinogram (ERG) and fundus photography were performed prior to injection. At days 1, 7, and 21 postinjection, ERG and fundus photography of each eye were performed. At last follow-up, Group C animals with highest drug concentration were sacrificed and the enucleated eyes were evaluated for retinal toxicity using transmission electron microscopy (TEM). Results: No difference in ERG responses was observed in eyes injected with low and intermediate concentration of natalizumab between day 0 and day 21. Furthermore, rabbits injected intravitreally with highest dose showed reduction in amplitude of “a” wave (P = 0.0017) and a reduction in amplitude of “b” wave of ERG at day 21 (P = 0.0117). TEM revealed changes in the outer plexiform layer and inner nuclear layer, suggestive of toxicity primarily to the photoreceptor synaptic terminals and bipolar cells. Conclusion: Low-dose (0.625 mg) and intermediate-dose (1.25 mg) intravitreal injection of natalizumab appears safe for rabbit retina. However, functional and anatomical changes were observed in rabbit retina following a high-dose (2.5 mg) intravitreal injection of a monoclonal antibody blocking α4β1 integrin.
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Affiliation(s)
- Rohan Chawla
- Department of Ophthalmology, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, India
| | - Madhu Nath
- Department of Ocular Pharmacology and Pharmacy, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, India
| | - Laxmi Moksha
- Department of Ocular Pharmacology and Pharmacy, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, India
| | - Tapas C Nag
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Thirumurthy Velpandian
- Department of Ocular Pharmacology and Pharmacy, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, India
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Gramage E, Li J, Hitchcock P. The expression and function of midkine in the vertebrate retina. Br J Pharmacol 2014; 171:913-23. [PMID: 24460673 PMCID: PMC3925030 DOI: 10.1111/bph.12495] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 10/21/2013] [Accepted: 10/24/2013] [Indexed: 12/20/2022] Open
Abstract
The functional role of midkine during development, following injury and in disease has been studied in a variety of tissues. In this review, we summarize what is known about midkine in the vertebrate retina, focusing largely on recent studies utilizing the zebrafish (Danio rerio) as an animal model. Zebrafish are a valuable animal model for studying the retina, due to its very rapid development and amazing ability for functional neuronal regeneration following neuronal cell death. The zebrafish genome harbours two midkine paralogues, midkine-a (mdka) and midkine-b (mdkb), which, during development, are expressed in nested patterns among different cell types. mdka is expressed in the retinal progenitors and mdkb is expressed in newly post-mitotic cells. Interestingly, studies of loss-and gain-of-function in zebrafish larvae indicate that midkine-a regulates cell cycle kinetics. Moreover, both mdka and mdkb are expressed in different cell types in the normal adult zebrafish retina, but after light-induced death of photoreceptors, both are up-regulated and expressed in proliferating Müller glia and photoreceptor progenitors, suggesting an important and (perhaps) coincident role for these cytokines during stem cell-based neuronal regeneration. Based on its known role in other tissues and the expression and function of the midkine paralogues in the zebrafish retina, we propose that midkine has an important functional role both during development and regeneration in the retina. Further studies are needed to understand this role and the mechanisms that underlie it.
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Affiliation(s)
- E Gramage
- Department of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, MI, USA
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Gaublomme D, Buyens T, De Groef L, Stakenborg M, Janssens E, Ingvarsen S, Porse A, Behrendt N, Moons L. Matrix metalloproteinase 2 and membrane type 1 matrix metalloproteinase co-regulate axonal outgrowth of mouse retinal ganglion cells. J Neurochem 2014; 129:966-79. [PMID: 24611815 DOI: 10.1111/jnc.12703] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 01/15/2023]
Abstract
Restoration of correct neural activity following central nervous system (CNS) damage requires the replacement of degenerated axons with newly outgrowing, functional axons. Unfortunately, spontaneous regeneration is largely lacking in the adult mammalian CNS. In order to establish successful regenerative therapies, an improved understanding of axonal outgrowth and the various molecules influencing it, is highly needed. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Using an ex vivo retinal explant model, we were able to show that broad-spectrum MMP inhibition reduces axon outgrowth of mouse retinal ganglion cells (RGCs), implicating MMPs as beneficial factors in axonal regeneration. Additional studies, using more specific MMP inhibitors and MMP-deficient mice, disclosed that both MMP-2 and MT1-MMP, but not MMP-9, are involved in this process. Furthermore, administration of a novel antibody to MT1-MMP that selectively blocks pro-MMP-2 activation revealed a functional co-involvement of these proteinases in determining RGC axon outgrowth. Subsequent immunostainings showed expression of both MMP-2 and MT1-MMP in RGC axons and glial cells. Finally, results from combined inhibition of MMP-2 and β1-integrin were suggestive for a functional interaction between these molecules. Overall, our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules. Axonal regeneration in the central nervous system is lacking in adult mammals, thereby impeding recovery from injury to the nervous system. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Inhibition of specific MMPs reduced neurite outgrowth from mouse retinal explants. Our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules and show a possible link between MMP-2 and β1-integrin in axon outgrowth.
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Affiliation(s)
- Djoere Gaublomme
- Department of Biology, Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, KU Leuven, Leuven, Belgium
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Proregenerative properties of ECM molecules. BIOMED RESEARCH INTERNATIONAL 2013; 2013:981695. [PMID: 24195084 PMCID: PMC3782155 DOI: 10.1155/2013/981695] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/04/2013] [Accepted: 08/07/2013] [Indexed: 12/27/2022]
Abstract
After traumatic injuries to the nervous system, regrowing axons encounter a complex microenvironment where mechanisms that promote regeneration compete with inhibitory processes. Sprouting and axonal regrowth are key components of functional recovery but are often counteracted by inhibitory molecules. This review covers extracellular matrix molecules that support neuron axonal outgrowth.
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Gaublomme D, Buyens T, Moons L. Automated Analysis of Neurite Outgrowth in Mouse Retinal Explants. ACTA ACUST UNITED AC 2012; 18:534-43. [DOI: 10.1177/1087057112471989] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Despite intensive research efforts over the past years, regeneration of injured axons in the central nervous system remains elusive. In the quest for neurostimulatory agents that promote regeneration, well-defined models and analysis methods are required. Tissue explant cultures closely resemble the in vivo situation, making them ideal to study the effect of compounds on the neuro-glial network. This study reports the optimization of an explant culture technique using retinas of neonatal mice and the development of an analysis script that allows for rapid and automated analysis of neurite outgrowth from these explants. The key features of this script (i.e., local thresholding and form selection) allow for swift and unbiased detection of neurite outgrowth. The novel analysis method is compared with two commonly used manual methods and successfully validated by performing dose-response studies with molecules known to either inhibit (anti–β1-integrin antibody) or stimulate (brain-derived neurotrophic factor and ciliary neurotrophic factor) neurite outgrowth from retinal explants. Finally, the new analysis script is used to study whether retinal explant origin has any effect on neurite outgrowth.
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Affiliation(s)
- Djoere Gaublomme
- Department of Biology, KU Leuven, Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, Leuven, Belgium
| | - Tom Buyens
- Department of Biology, KU Leuven, Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, Leuven, Belgium
| | - Lieve Moons
- Department of Biology, KU Leuven, Laboratory of Neural Circuit Development and Regeneration, Animal Physiology and Neurobiology Section, Leuven, Belgium
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7
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Osteopontin is upregulated after mechanical brain injury and stimulates neurite growth from hippocampal neurons through β1 integrin and CD44. Neuroreport 2012; 23:647-52. [PMID: 22692550 DOI: 10.1097/wnr.0b013e328355380e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Brain trauma induces a multitude of reactions at molecular, cellular, and tissue levels, some of which are beneficial to recovery, whereas others are detrimental. Osteopontin (OPN), a glycosylated phosphoprotein, can be found in both the soluble form and as an extracellular matrix constituent in several tissues in the vertebrate body, but its function after brain injury is largely unknown. In this study, the expression of OPN after an experimental traumatic brain injury in rats was examined and its effects on hippocampal neurons and cortical astrocytes were studied using cell-culture techniques. OPN had no influence astrocyte behavior in a scratch assay. However, hippocampal neurons grew well on an OPN substrate with growth comparable to that seen on laminin, but showed a higher degree of primary neurites. Finally, growth on OPN was mediated through β1 intregrins and CD44. These findings indicate that injury-induced OPN may support neurite sprouting, suggesting a role for this molecule in recovery from central nervous system trauma.
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Tonge DA, de Burgh HT, Docherty R, Humphries MJ, Craig SE, Pizzey J. Fibronectin supports neurite outgrowth and axonal regeneration of adult brain neurons in vitro. Brain Res 2012; 1453:8-16. [PMID: 22483961 PMCID: PMC3989037 DOI: 10.1016/j.brainres.2012.03.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 03/03/2012] [Accepted: 03/09/2012] [Indexed: 12/09/2022]
Abstract
The molecular basis of axonal regeneration of central nervous system (CNS) neurons remains to be fully elucidated. In part, this is due to the difficulty in maintaining CNS neurons in vitro. Here, we show that dissociated neurons from the cerebral cortex and hippocampus of adult mice may be maintained in culture for up to 9 days in defined medium without added growth factors. Outgrowth of neurites including axons was observed from both CNS sources and was significantly greater on plasma fibronectin than on other substrata such as laminin and merosin. Neurite outgrowth on fibronectin appears to be mediated by α5β1 integrin since a recombinant fibronectin fragment containing binding sites for this receptor was as effective as intact fibronectin in supporting neurite outgrowth. Conversely, function-blocking antibodies to α5 and β1 integrin sub-units inhibited neurite outgrowth on intact fibronectin. These results suggest that the axonal regeneration seen in in vivo studies using fibronectin-based matrices is due to the molecule itself and not a consequence of secondary events such as cellular infiltration. They also indicate the domains of fibronectin that may be responsible for eliciting this response.
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Affiliation(s)
- David A Tonge
- Wolfson-Centre for Age-Related Disease, King's College London, Hodgkin Building, Guy's Campus, London SE1 1UL, UK
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9
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Myers JP, Santiago-Medina M, Gomez TM. Regulation of axonal outgrowth and pathfinding by integrin-ECM interactions. Dev Neurobiol 2011; 71:901-23. [PMID: 21714101 PMCID: PMC3192254 DOI: 10.1002/dneu.20931] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Developing neurons use a combination of guidance cues to assemble a functional neural network. A variety of proteins immobilized within the extracellular matrix (ECM) provide specific binding sites for integrin receptors on neurons. Integrin receptors on growth cones associate with a number of cytosolic adaptor and signaling proteins that regulate cytoskeletal dynamics and cell adhesion. Recent evidence suggests that soluble growth factors and classic axon guidance cues may direct axon pathfinding by controlling integrin-based adhesion. Moreover, because classic axon guidance cues themselves are immobilized within the ECM and integrins modulate cellular responses to many axon guidance cues, interactions between activated receptors modulate cell signals and adhesion. Ultimately, growth cones control axon outgrowth and pathfinding behaviors by integrating distinct biochemical signals to promote the proper assembly of the nervous system. In this review, we discuss our current understanding how ECM proteins and their associated integrin receptors control neural network formation.
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Affiliation(s)
- Jonathan P Myers
- Department of Neuroscience, Neuroscience Training Program, University of Wisconsin, Madison, Wisconsin 53706, USA
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10
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Gardiner NJ. Integrins and the extracellular matrix: Key mediators of development and regeneration of the sensory nervous system. Dev Neurobiol 2011; 71:1054-72. [DOI: 10.1002/dneu.20950] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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11
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Schwinn MK, Gonzalez JM, Gabelt BT, Sheibani N, Kaufman PL, Peters DM. Heparin II domain of fibronectin mediates contractility through an alpha4beta1 co-signaling pathway. Exp Cell Res 2010; 316:1500-12. [PMID: 20302860 DOI: 10.1016/j.yexcr.2010.03.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 02/26/2010] [Accepted: 03/10/2010] [Indexed: 01/12/2023]
Abstract
In the trabecular meshwork (TM) of the eye, regulation of tissue contractility by the PPRARI sequence within the Heparin II (HepII) domain of fibronectin is believed to control the movement of aqueous humor and dictate the level of intraocular pressure. This study shows that the HepII domain utilizes activated alpha4beta1 integrin and collagen to mediate a co-signaling pathway that down-regulates contractility in TM cells. siRNA silencing of alpha4beta1 integrin blocked the actin disrupting effects of both PPRARI and the HepII domain. The down-regulation of the actin cytoskeleton and contractility did not involve syndecan-4 or other heparan sulfate proteoglycans (HSPGs) since siRNA silencing of syndecan-4 expression or heparitinase removal of cell surface HSPGs did not prevent the HepII-mediated disruption of the actin cytoskeleton. HepII-mediated disruption of the cytoskeleton depended upon the presence of collagen in the extracellular matrix, and cell binding studies indicated that HepII signaling involved cross-talk between alpha4beta1 and alpha1/alpha2beta1 integrins. This is the first time that the PPRARI sequence in the HepII domain has been shown to serve as a physiological alpha4beta1 ligand, suggesting that alpha4beta1 integrin may be a key regulator of tissue contractility.
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Affiliation(s)
- Marie K Schwinn
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706, USA
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12
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Ma CHE, Bampton ETW, Evans MJ, Taylor JSH. Synergistic effects of osteonectin and brain-derived neurotrophic factor on axotomized retinal ganglion cells neurite outgrowth via the mitogen-activated protein kinase-extracellular signal-regulated kinase 1/2 pathways. Neuroscience 2010; 165:463-74. [PMID: 19837135 DOI: 10.1016/j.neuroscience.2009.10.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 10/06/2009] [Accepted: 10/13/2009] [Indexed: 11/19/2022]
Abstract
Our previous study identified osteonectin (ON) in a screen of factors made by Schwann cells (SCs) which promoted peripheral and central neurons survival and neuritogenesis, however, the mechanisms of ON promoting effects are largely unknown. In the present study, we investigated the effects of ON-deficient SC-conditioned medium (SCCM) and molecular mechanisms of ON, in regulating retinal ganglion cells (RGCs) survival and neurite outgrowth. Neonatal rat RGCs and SCs were purified by immunopanning technique. RGC survival and neuritogenesis reduced significantly when treated with either ON-null mice SCCM or ON-immunodepleted (IP) SCCM (P<0.05). In contrast to wild type SCCM, in the presence of a tyrosine kinase receptor (Trk) inhibitor (K252a), ON-null mice SCCM-induced neuritogenesis were further reduced by 24%. The Trk-mediated signaling pathways became more sensitive to K252a inhibition in the absence of ON. We also showed the synergistic effects of ON and brain-derived neurotrophic factor (BDNF) in promoting RGCs growth and the involvement of ON in two major neurotrophin-mediated signaling pathways, PI-3K-Akt and MAPK-Erk1/2. ON alone activated Akt phosphorylation and increased survival. Blockage of TrkB signalling pathway by TrkB-Fc chimera (BDNF scavenger) or K252a in ON-treated cultures reduced Akt-P level significantly. This suggests that ON induces BDNF synthesis and secretion from RGCs. The enhancement of neuritogenesis and Erk1/2 phosphorylation by ON in BDNF-treated cultures further demonstrate the signaling pathways responsible for the synergistic effect of ON on BDNF-induced neurite outgrowth. To the best of our knowledge, this is the first report showing the synergistic effects of ON on classical neurotrophins which participate in the same signalling pathways in regulating RGC neurite outgrowth.
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Affiliation(s)
- C H E Ma
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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Ries A, Goldberg JL, Grimpe B. A novel biological function for CD44 in axon growth of retinal ganglion cells identified by a bioinformatics approach. J Neurochem 2007; 103:1491-505. [PMID: 17760872 PMCID: PMC2901540 DOI: 10.1111/j.1471-4159.2007.04858.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The failure of CNS regeneration and subsequent motor and sensory loss remain major unsolved questions despite massive accumulation of experimental observations and results. The sheer volume of data and the variety of resources from which these data are generated make it difficult to integrate prior work to build new hypotheses. To address these challenges we developed a prototypic suite of computer programs to extract protein names from relevant publications and databases and associated each of them with several general categories of biological functions in nerve regeneration. To illustrate the usefulness of our data mining approach, we utilized the program output to generate a hypothesis for a biological function of CD44 interaction with osteopontin (OPN) and laminin in axon outgrowth of CNS neurons. We identified CD44 expression in retinal ganglion cells and when these neurons were plated on poly-l-lysine 3% of them initiated axon growth, on OPN 15%, on laminin-111 (1x) 41%, on laminin-111 (0.5x) 56%, and on a mixture of OPN and laminin (1x) 67% of neurons generated axon growth. With the aid of a deoxyribozyme (DNA enzyme) to CD44 that digests the target mRNA, we demonstrated that a reduction of CD44 expression led to reduced axon initiation of retinal ganglion cells on all substrates. We suggest that such an integrative, applied systems biology approach to CNS trauma will be critical to understand and ultimately overcome the failure of CNS regeneration.
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Affiliation(s)
- Albert Ries
- Department of Cell Biology, Max Planck Institute of Biochemistry, Munich, Germany
| | | | - Barbara Grimpe
- The Miami Project to Cure Paralysis, University of Miami, Miami, Florida, USA
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Marsh BC, Kerr NC, Isles N, Denhardt DT, Wynick D. Osteopontin expression and function within the dorsal root ganglion. Neuroreport 2007; 18:153-7. [PMID: 17301681 PMCID: PMC2725313 DOI: 10.1097/wnr.0b013e328010d4fa] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Osteopontin expression has previously been demonstrated in the adult rat dorsal root ganglion, although its function remains unclear. Here, we demonstrate, using real-time reverse transcription-polymerase (RT-PCR) chain reaction, that osteopontin mRNA expression is increased 1 and 3 weeks following sciatic nerve section (axotomy). Further, immunohistochemical staining suggests that this increase is restricted to neurons already expressing the protein. Osteopontin knock-out animals have significantly increased mechanosensory thresholds in the intact adult compared with the wild-type controls; however no differences in allodynia are noted between genotypes using a model of neuropathic pain. Lastly, exogenous recombinant osteopontin has no effect on neurite outgrowth from adult wild-type sensory neurons, nor were differences in neurite outgrowth observed in osteopontin knock-out animals compared with wild-type controls.
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Affiliation(s)
- Barnaby C.L. Marsh
- Departments of Pharmacology and Clinical Sciences at South Bristol,University of Bristol, Bristol,UK
| | - Niall C. Kerr
- Departments of Pharmacology and Clinical Sciences at South Bristol,University of Bristol, Bristol,UK
| | - Nathalie Isles
- Departments of Pharmacology and Clinical Sciences at South Bristol,University of Bristol, Bristol,UK
| | - David T. Denhardt
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, USA
| | - David Wynick
- Departments of Pharmacology and Clinical Sciences at South Bristol,University of Bristol, Bristol,UK
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15
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Wingerd KL, Wayne WC, Jackson DY, Clegg DO. Involvement of alpha4 integrins in maintenance of cardiac sympathetic axons. Auton Neurosci 2005; 122:58-68. [PMID: 16181811 DOI: 10.1016/j.autneu.2005.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 08/01/2005] [Accepted: 08/06/2005] [Indexed: 11/15/2022]
Abstract
Sympathetic neurons extend and maintain axons that innervate the myocardium, and proper innervation is important for cardiac function. However, the molecular basis for axon outgrowth and maintenance is not well understood. We have shown previously that the integrin alpha4beta1 is expressed on developing axons, and the alpha4 function is important for the development of innervation in vivo [Wingerd, K.L., Goodman, N.L., Tresser, J.W., Smail, M.M., Leu, S.T., Rohan, S.J., Pring, J.L., Jackson, D.Y., and Clegg, D.O., 2002. Alpha 4 integrins and vascular cell adhesion molecule-1 play a role in sympathetic innervation of the heart. J. Neurosci. 22,10772-10780]. Here we examine the function of alpha4beta1 integrins in the maintenance of cardiac sympathetic innervation in vitro and in vivo, and investigate integrin expression and function after myocardial infarction and in hypertensive rats. On substrates of vascular cell adhesion molecule-1 (VCAM-1), alpha4beta1 was required for both initial outgrowth and maintenance of neurites in vitro. On fibronectin substrates, initial outgrowth requires only alpha4 integrins, but maintenance requires both alpha4 integrins and RGD-dependent integrins. In vivo, in adult Long Evans rats, inhibition of alpha4 integrins resulted in decreased maintenance of sympathetic fibers innervating the apex of the heart. However, alpha4 integrins were not detected on most sympathetic axons that sprout after myocardial infarction, and alpha4 function was not required for sprouting. Spontaneously hypertensive rats (SHR) have increased numbers of cardiac sympathetic fibers compared to the parental Wistar strain, but many of these lack alpha4 expression, and alpha4 function is not required for maintenance of these fibers in the heart. These results suggest that developing sympathetic axons and sprouting sympathetic axons use different mechanisms of outgrowth, and that maintenance of cardiac sympathetic innervation involves alpha4 integrins in some rat strains.
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Affiliation(s)
- Kevin L Wingerd
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
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16
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Leu ST, Jacques SAL, Wingerd KL, Hikita ST, Tolhurst EC, Pring JL, Wiswell D, Kinney L, Goodman NL, Jackson DY, Clegg DO. Integrin α4β1 function is required for cell survival in developing retina. Dev Biol 2004; 276:416-30. [PMID: 15581875 DOI: 10.1016/j.ydbio.2004.09.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2004] [Revised: 08/31/2004] [Accepted: 09/01/2004] [Indexed: 11/24/2022]
Abstract
In the retina, integrins in the beta1 family have been shown to be important in many phases of neuronal development, particularly neuroblast migration and axon outgrowth. However, the functions of specific integrin heterodimers are not well defined. In this study, we investigated the functions of beta1 integrins in developing chicken retina by expression of a dominant-negative beta1A construct using a replication-competent retrovirus. Inhibition of integrins using this approach resulted in alteration of cell morphology and increased apoptosis, but did not preclude migration and axon elongation. In an attempt to identify which specific beta1 heterodimer was important, expression and function of the alpha4beta1 heterodimer were also investigated. At early developmental stages, alpha4 protein and mRNA were detected in undifferentiated neuroblasts throughout the retina. At later stages, expression was confined to retinal ganglion cells (RGCs) and amacrine cells. A small molecule antagonist of alpha4 integrins was shown to inhibit neurite outgrowth on recombinant soluble vascular cell adhesion molecule-1 (VCAM-1), a known ligand of alpha4beta1. Introduction of alpha4 antagonist in vivo gave rise to increased apoptosis and led to a thinning of the retina and reduced numbers of retinal ganglion cells (RGCs). We conclude that the integrin alpha4beta1 is important for survival of developing retinal neurons, including RGCs.
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Affiliation(s)
- Sergiu T Leu
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
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Wingerd KL, Goodman NL, Leu ST, Clegg DO. Expression and function of integrin ?4?1 and vascular cell adhesion molecule-1 (VCAM-1) during sympathetic innervation of the heart. Dev Dyn 2004; 231:359-69. [PMID: 15366013 DOI: 10.1002/dvdy.20120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The interaction between the integrin alpha4beta1 receptor on superior cervical ganglion (SCG) neurons and vascular cell adhesion molecule-1 (VCAM-1) in cardiac tissue has been implicated in proper development of the sympathetic innervation of the heart (Wingerd et al. [2002] J Neurosci 22:10772-10780). In this study, we examined the expression and function of alpha4beta1 and VCAM-1 in developing rat SCG and heart. In vitro, the alpha4beta1-dependent neurite outgrowth on VCAM-1 decreased by approximately 50% from postnatal day 1 to 6. This down-regulation was correlated with a shift in alpha4 isoform and a shift in alpha4 localization from neurites to cell bodies. This altered localization was also observed in vivo but on a different time scale. alpha4 was detected on most developing SCG neurons and on macrophages and blood vessels. In the heart, alpha4 was detected on sympathetic axons, but the percentage of alpha4-positive fibers decreased with age. VCAM-1 immunoreactivity was abundant in heart tissue throughout development, in close proximity to sympathetic axons. The regulation of alpha4beta1 function, and localization of alpha4 and VCAM-1, are consistent with a role for the alpha4beta1--VCAM-1 interaction in extension of sympathetic axons into the myocardium.
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Affiliation(s)
- Kevin L Wingerd
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA
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