101
|
Nerve Growth Factor Regulates Transient Receptor Potential Vanilloid 2 via Extracellular Signal-Regulated Kinase Signaling To Enhance Neurite Outgrowth in Developing Neurons. Mol Cell Biol 2015; 35:4238-52. [PMID: 26416880 DOI: 10.1128/mcb.00549-15] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/21/2015] [Indexed: 12/13/2022] Open
Abstract
Neurite outgrowth is key to the formation of functional circuits during neuronal development. Neurotrophins, including nerve growth factor (NGF), increase neurite outgrowth in part by altering the function and expression of Ca(2+)-permeable cation channels. Here we report that transient receptor potential vanilloid 2 (TRPV2) is an intracellular Ca(2+)-permeable TRPV channel upregulated by NGF via the mitogen-activated protein kinase (MAPK) signaling pathway to augment neurite outgrowth. TRPV2 colocalized with Rab7, a late endosome protein, in addition to TrkA and activated extracellular signal-regulated kinase (ERK) in neurites, indicating that the channel is closely associated with signaling endosomes. In line with these results, we showed that TRPV2 acts as an ERK substrate and identified the motifs necessary for phosphorylation of TRPV2 by ERK. Furthermore, neurite length, TRPV2 expression, and TRPV2-mediated Ca(2+) signals were reduced by mutagenesis of these key ERK phosphorylation sites. Based on these findings, we identified a previously uncharacterized mechanism by which ERK controls TRPV2-mediated Ca(2+) signals in developing neurons and further establish TRPV2 as a critical intracellular ion channel in neuronal function.
Collapse
|
102
|
Chen Z, Zhang W, Ni L, Wang G, Cao Y, Wu W, Sun C, Yuan D, Ni H, Wang Y, Yang H. Spatiotemporal Expression of Poly(rC)-Binding Protein PCBP2 Modulates Schwann Cell Proliferation After Sciatic Nerve Injury. Cell Mol Neurobiol 2015; 36:725-35. [PMID: 26250704 DOI: 10.1007/s10571-015-0253-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 07/31/2015] [Indexed: 12/16/2022]
Abstract
Poly(C)-binding proteins (PCBPs), also known as RNA-binding proteins, interact in a sequence-specific fashion with single-stranded poly(C). It was reported that PCBP2 contributed to gastric cancer proliferation and survival through miR-34a, and knockdown of PCBP2 inhibited glioma proliferation through inhibition of cell cycle progression. In addition, PCBP2 might play a critical role in the regulation of cortical neurons apoptosis induced by hypoxia or ischemia. Because of the essential role of PCBP2 in nervous system and cell growth, we investigated the spatiotemporal expression of PCBP2 in a rat sciatic nerve crush (SNC) model. We detected the upregulated expression of PCBP2 in Schwann cell after SNC. Besides, the peak expression of PCBP2 was in parallel with proliferation cell nuclear antigen. In vitro, we observed increased expression of PCBP2 during the process of TNF-α-induced Schwann cell proliferation. Specially, PCBP2-specific siRNA-transfected Schwann cell showed significantly decreased ability for proliferation. Together, all these data indicated that the change of PCBP2 protein expression was associated with Schwann cell proliferation after the trauma of the peripheral nervous system.
Collapse
Affiliation(s)
- Zhigang Chen
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, Jiangsu, People's Republic of China.,Department of Orthopedic Surgery, The Affiliated Hai'an Hospital of Nantong University, 17 Zhongba Middle Road, Hai'an, 226600, Jiangsu, People's Republic of China
| | - Weidong Zhang
- Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Li Ni
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, Jiangsu, People's Republic of China
| | - Genlin Wang
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, Jiangsu, People's Republic of China
| | - Yi Cao
- Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Weijie Wu
- Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Chi Sun
- Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Damin Yuan
- Department of Immunology, Medical College, Nantong University, Nantong, 226001, People's Republic of China
| | - Haidan Ni
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Youhua Wang
- Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | - Huilin Yang
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, Jiangsu, People's Republic of China.
| |
Collapse
|
103
|
Kegler K, Spitzbarth I, Imbschweiler I, Wewetzer K, Baumgärtner W, Seehusen F. Contribution of Schwann Cells to Remyelination in a Naturally Occurring Canine Model of CNS Neuroinflammation. PLoS One 2015. [PMID: 26196511 PMCID: PMC4510361 DOI: 10.1371/journal.pone.0133916] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Gliogenesis under pathophysiological conditions is of particular clinical relevance since it may provide evidence for regeneration promoting cells recruitable for therapeutic purposes. There is evidence that neurotrophin receptor p75 (p75NTR)-expressing cells emerge in the lesioned CNS. However, the phenotype and identity of these cells, and signals triggering their in situ generation under normal conditions and certain pathological situations has remained enigmatic. In the present study, we used a spontaneous, idiopathic and inflammatory CNS condition in dogs with prominent lympho-histiocytic infiltration as a model to study the phenotype of Schwann cells and their relation to Schwann cell remyelination within the CNS. Furthermore, the phenotype of p75NTR-expressing cells within the injured CNS was compared to their counter-part in control sciatic nerve and after peripheral nerve injury. In addition, organotypic slice cultures were used to further elucidate the origin of p75NTR-positive cells. In cerebral and cerebellar white and grey matter lesions as well as in the brain stem, p75NTR-positive cells co-expressed the transcription factor Sox2, but not GAP-43, GFAP, Egr2/Krox20, periaxin and PDGFR-α. Interestingly, and contrary to the findings in control sciatic nerves, p75NTR-expressing cells only co-localized with Sox2 in degenerative neuropathy, thus suggesting that such cells might represent dedifferentiated Schwann cells both in the injured CNS and PNS. Moreover, effective Schwann cell remyelination represented by periaxin- and P0-positive mature myelinating Schwann cells, was strikingly associated with the presence of p75NTR/Sox2-expressing Schwann cells. Intriguingly, the emergence of dedifferentiated Schwann cells was not affected by astrocytes, and a macrophage-dominated inflammatory response provided an adequate environment for Schwann cells plasticity within the injured CNS. Furthermore, axonal damage was reduced in brain stem areas with p75NTR/Sox2-positive cells. This study provides novel insights into the involvement of Schwann cells in CNS remyelination under natural occurring CNS inflammation. Targeting p75NTR/Sox2-expressing Schwann cells to enhance their differentiation into competent remyelinating cells appears to be a promising therapeutic approach for inflammatory/demyelinating CNS diseases.
Collapse
Affiliation(s)
- Kristel Kegler
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
- Center of Systems Neuroscience, Hannover, Germany
| | - Ingo Spitzbarth
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
- Center of Systems Neuroscience, Hannover, Germany
| | - Ilka Imbschweiler
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
| | - Konstantin Wewetzer
- Center of Systems Neuroscience, Hannover, Germany
- Department of Functional and Applied Anatomy, Center of Anatomy, Hannover Medical School, Hannover, Germany
| | - Wolfgang Baumgärtner
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
- Center of Systems Neuroscience, Hannover, Germany
- * E-mail:
| | - Frauke Seehusen
- Department of Pathology, University of Veterinary Medicine, Hannover, Germany
| |
Collapse
|
104
|
Abstract
Eye pain is an unpleasant sensory and emotional experience including sensory-discriminative, emotional, cognitive, and behavioral components and supported by distinct, interconnected peripheral and central nervous system elements. Normal or physiological pain results of the stimulation by noxious stimuli of sensory axons of trigeminal ganglion (TG) neurons innervating the eye. These are functionally heterogeneous. Mechano-nociceptors are only excited by noxious mechanical forces. Polymodal nociceptors also respond to heat, exogenous irritants, and endogenous inflammatory mediators, whereas cold thermoreceptors detect moderate temperature changes. Their distinct sensitivity to stimulating forces is determined by the expression of specific classes of ion channels: Piezo2 for mechanical forces, TRPV1 and TRPA1 for heat and chemical agents, and TRPM8 for cold. Pricking pain is evoked by mechano-nociceptors, while polymodal nociceptors are responsible of burning and stinging eye pain; sensations of dryness appear to be mainly evoked by cold thermoreceptors. Mediators released by local inflammation, increase the excitability of eye polymodal nociceptors causing their sensitization and the augmented pain sensations. During chronic inflammation, additional, long-lasting changes in the expression and function of stimulus-transducing and voltage-sensitive ion channels develop, thereby altering polymodal terminal's excitability and evoking chronic inflammatory pain. When trauma, infections, or metabolic processes directly damage eye nerve terminals, these display aberrant impulse firing due to an abnormal expression of transducing and excitability-modulating ion channels. This malfunction evokes 'neuropathic pain' which may also result from abnormal function of higher brain structures where ocular TG neurons project. Eye diseases or ocular surface surgery cause different levels of inflammation and/or nerve injury, which in turn activate sensory fibers of the eye in a variable degree. When inflammation dominates (allergic or actinic kerato-conjunctivitis), polymodal nociceptors are primarily stimulated and sensitized, causing pain. In uncomplicated photorefractive surgery and moderate dry eye, cold thermoreceptors appear to be mainly affected, evoking predominant sensations of unpleasant dryness.
Collapse
Affiliation(s)
- Carlos Belmonte
- />Instituto de Neurociencias, Universidad Miguel Hernández-CSIC San Juan de Alicante, Avenida de la Universidad, s/n, 03202 Alicante, Spain
- />Instituto Fernandez Vega, Fundación de Investigación Oftalmológica, Av Doctores Fernández Vega, 34, 33012 Oviedo, Asturias Spain
| | - M. Carmen Acosta
- />Instituto de Neurociencias, Universidad Miguel Hernández-CSIC San Juan de Alicante, Avenida de la Universidad, s/n, 03202 Alicante, Spain
| | - Jesus Merayo-Lloves
- />Instituto Fernandez Vega, Fundación de Investigación Oftalmológica, Av Doctores Fernández Vega, 34, 33012 Oviedo, Asturias Spain
| | - Juana Gallar
- />Instituto de Neurociencias, Universidad Miguel Hernández-CSIC San Juan de Alicante, Avenida de la Universidad, s/n, 03202 Alicante, Spain
| |
Collapse
|
105
|
Zhang W, Zhu X, Liu Y, Chen M, Yan S, Mao X, Liu Z, Wu W, Chen C, Xu X, Wang Y. Nur77 Was Essential for Neurite Outgrowth and Involved in Schwann Cell Differentiation After Sciatic Nerve Injury. J Mol Neurosci 2015; 57:38-47. [PMID: 25957997 DOI: 10.1007/s12031-015-0575-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/29/2015] [Indexed: 12/23/2022]
Abstract
Nur77, together with Nurr1 and NOR-1, constitutes the NR4A subgroup of orphan nuclear receptors and plays critical roles in cell proliferation, differentiation, migration, and apoptosis. Among them, Nur77 is universally well known to contribute to neurite outgrowth. However, information regarding its regulation and possible function in the peripheral nervous system is still limited. In this study, we performed a sciatic nerve injury model in adult rats and detected an increased expression of Nur77 in the sciatic nerve, which was similar to the expression of Oct-6. Immunofluorescence indicated that Nur77 was located in both axons and Schwann cells. In vitro, we observed enhanced expression of Nur77 during the process of both basic fibroblast growth factor (bFGF)-induced Schwann cells differentiation and nerve growth factor (NGF)-induced PC12 cell neurite outgrowth. In vitro and in vivo experiments indicated that inhibiting the function of Nur77 by specific short hairpin RNA could depress Schwann cells myelinization and axons regeneration. Collectively, all these results suggested that upregulation of Nur77 might be involved in Schwann cells differentiation and neurite elongation following sciatic nerve crush.
Collapse
Affiliation(s)
- Weidong Zhang
- Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
106
|
Hoyng SA, De Winter F, Gnavi S, van Egmond L, Attwell CL, Tannemaat MR, Verhaagen J, Malessy MJA. Gene delivery to rat and human Schwann cells and nerve segments: a comparison of AAV 1–9 and lentiviral vectors. Gene Ther 2015; 22:767-80. [DOI: 10.1038/gt.2015.47] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 03/29/2015] [Accepted: 04/27/2015] [Indexed: 12/17/2022]
|
107
|
Østergaard L, Finnerup NB, Terkelsen AJ, Olesen RA, Drasbek KR, Knudsen L, Jespersen SN, Frystyk J, Charles M, Thomsen RW, Christiansen JS, Beck-Nielsen H, Jensen TS, Andersen H. The effects of capillary dysfunction on oxygen and glucose extraction in diabetic neuropathy. Diabetologia 2015; 58:666-77. [PMID: 25512003 PMCID: PMC4351434 DOI: 10.1007/s00125-014-3461-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 11/06/2014] [Indexed: 12/14/2022]
Abstract
Diabetic neuropathy is associated with disturbances in endoneurial metabolism and microvascular morphology, but the roles of these factors in the aetiopathogenesis of diabetic neuropathy remain unclear. Changes in endoneurial capillary morphology and vascular reactivity apparently predate the development of diabetic neuropathy in humans, and in manifest neuropathy, reductions in nerve conduction velocity correlate with the level of endoneurial hypoxia. The idea that microvascular changes cause diabetic neuropathy is contradicted, however, by reports of elevated endoneurial blood flow in early experimental diabetes, and of unaffected blood flow when early histological signs of neuropathy first develop in humans. We recently showed that disturbances in capillary flow patterns, so-called capillary dysfunction, can reduce the amount of oxygen and glucose that can be extracted by the tissue for a given blood flow. In fact, tissue blood flow must be adjusted to ensure sufficient oxygen extraction as capillary dysfunction becomes more severe, thereby changing the normal relationship between tissue oxygenation and blood flow. This review examines the evidence of capillary dysfunction in diabetic neuropathy, and whether the observed relation between endoneurial blood flow and nerve function is consistent with increasingly disturbed capillary flow patterns. The analysis suggests testable relations between capillary dysfunction, tissue hypoxia, aldose reductase activity, oxidative stress, tissue inflammation and glucose clearance from blood. We discuss the implications of these predictions in relation to the prevention and management of diabetic complications in type 1 and type 2 diabetes, and suggest ways of testing these hypotheses in experimental and clinical settings.
Collapse
Affiliation(s)
- Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Institute of Clinical Medicine, Aarhus University Hospital, Building 10G, Nørrebrogade 44, DK-8000, Aarhus C, Denmark,
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
108
|
Castorina A, Waschek JA, Marzagalli R, Cardile V, Drago F. PACAP interacts with PAC1 receptors to induce tissue plasminogen activator (tPA) expression and activity in schwann cell-like cultures. PLoS One 2015; 10:e0117799. [PMID: 25658447 PMCID: PMC4319891 DOI: 10.1371/journal.pone.0117799] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 12/31/2014] [Indexed: 12/13/2022] Open
Abstract
Regeneration of peripheral nerves depends on the abilities of rejuvenating axons to migrate at the injury site through cellular debris and altered extracellular matrix, and then grow along the residual distal nerve sheath conduit and reinnervate synaptic targets. Considerable evidence suggest that glial cells participate in this process, although the mechanisms remain to be clarified. In cell culture, regenerating neurites secrete PACAP, a peptide shown to induce the expression of the protease tissue plasminogen activator (tPA) in neural cell types. In the present studies, we tested the hypothesis that PACAP can stimulate peripheral glial cells to produce tPA. More specifically, we addressed whether or not PACAP promoted the expression and activity of tPA in the Schwann cell line RT4-D6P2T, which shares biochemical and physical properties with Schwann cells. We found that PACAP dose- and time-dependently stimulated tPA expression both at the mRNA and protein level. Such effect was mimicked by maxadilan, a potent PAC1 receptor agonist, but not by the PACAP-related homolog VIP, suggesting a PAC1-mediated function. These actions appeared to be mediated at least in part by the Akt/CREB signaling cascade because wortmannin, a PI3K inhibitor, prevented peptide-driven CREB phosphorylation and tPA increase. Interestingly, treatment with BDNF mimicked PACAP actions on tPA, but acted through both the Akt and MAPK signaling pathways, while causing a robust increase in PACAP and PAC1 expression. PACAP6-38 totally blocked PACAP-driven tPA expression and in part hampered BDNF-mediated effects. We conclude that PACAP, acting through PAC1 receptors, stimulates tPA expression and activity in a Akt/CREB-dependent manner to promote proteolytic activity in Schwann-cell like cultures.
Collapse
Affiliation(s)
- Alessandro Castorina
- Department of Biomedical Sciences and Biotechnologies, Section of Human Anatomy and Histology, University of Catania, Catania, Italy
- * E-mail:
| | - James A. Waschek
- Semel Institute/Department of Psychiatry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Rubina Marzagalli
- Department of Biomedical Sciences and Biotechnologies, Section of Human Anatomy and Histology, University of Catania, Catania, Italy
| | - Venera Cardile
- Department of Biomedical Sciences and Biotechnologies, Section of Physiology, University of Catania, Catania, Italy
| | - Filippo Drago
- Department of Biomedical Sciences and Biotechnologies, Section of Pharmacology, University of Catania, Catania, Italy
| |
Collapse
|
109
|
Vaegter CB. Neurotrophins and their receptors in satellite glial cells following nerve injury. Neural Regen Res 2015; 9:2038-9. [PMID: 25657715 PMCID: PMC4316462 DOI: 10.4103/1673-5374.147924] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2014] [Indexed: 11/28/2022] Open
Affiliation(s)
- Christian Bjerggaard Vaegter
- Danish Research Institute of Translational Neuroscience DANDRITE, Nordic EMBL Partnership, and The Lundbeck Foundation Research Center MIND, Department of Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus C, Denmark
| |
Collapse
|
110
|
Mattsson P, Hydman J, Svensson M. Recovery of laryngeal function after intraoperative injury to the recurrent laryngeal nerve. Gland Surg 2015; 4:27-35. [PMID: 25713777 PMCID: PMC4321052 DOI: 10.3978/j.issn.2227-684x.2015.01.10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 01/26/2015] [Indexed: 11/14/2022]
Abstract
Loss of function in the recurrent laryngeal nerve (RLN) during thyroid/parathyroid surgery, despite a macroscopically intact nerve, is a challenge which highlights the sensitivity and complexity of laryngeal innervation. Furthermore, the uncertain prognosis stresses a lack of capability to diagnose the reason behind the impaired function. There is a great deal of literature considering risk factors, surgical technique and mechanisms outside the nerve affecting the incidence of RLN paresis during surgery. To be able to prognosticate recovery in cases of laryngeal dysfunction and voice changes after thyroid surgery, the surgeon would first need to define the presence, location, and type of laryngeal nerve injury. There is little data describing the events within the nerve and the neurobiological reasons for the impaired function related to potential recovery and prognosis. In addition, very little data has been presented in order to clarify any differences between the transient and permanent injury of the RLN. This review aims, from an anatomical and neurobiological perspective, to provide an update on the current understandings of surgically-induced injury to the laryngeal nerves.
Collapse
Affiliation(s)
- Per Mattsson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Jonas Hydman
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Mikael Svensson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
111
|
Drummond PD, Dawson LF, Finch PM, Drummond ES, Wood FM, Fear MW. Up-regulation of cutaneous α1-adrenoceptors after a burn. Burns 2015; 41:1227-34. [PMID: 25630693 DOI: 10.1016/j.burns.2014.12.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 12/22/2014] [Accepted: 12/26/2014] [Indexed: 01/02/2023]
Abstract
Stimulation of α1-adrenoceptors evokes inflammatory cytokine production, boosts neurogenic inflammation and pain, and influences cellular migration and proliferation. As expression of α1-adrenoceptors increases on dermal nerves and keratinocytes after peripheral nerve injury, the aim of this study was to determine whether another form of tissue injury (a cutaneous burn) triggered a similar response. In particular, changes in expression of α1-adrenoceptors were investigated on dermal nerve fibres, keratinocytes and fibroblast-like cells using immunohistochemistry 2-12 weeks after a full thickness burn in Wistar rats. Within two weeks of the burn, local increases in α1-adrenoceptor expression were seen in the re-forming epidermis, in dense bands of spindle-shaped cells in the upper dermis (putatively infiltrating immune cells and fibroblasts), and on nerve fibres in the deep dermis. In addition, nerve fibre density increased approximately three-fold in the deep dermis, and this response persisted for several more weeks. In contrast, α1-adrenoceptor labelled cells and staining intensity in the upper dermis decreased contralateral to the burn, as did nerve fibre density in the deep dermis. These findings suggest that inflammatory mediators and/or growth factors at the site of a burn trigger the synthesis of α1-adrenoceptors on resident epidermal cells and nerve fibres, and an influx of α1-adrenoceptor labelled cells. The heightened expression of α1-adrenoceptors in injured tissue could shape inflammatory and wound healing responses.
Collapse
Affiliation(s)
- Peter D Drummond
- Centre for Research on Chronic Pain and Inflammatory Diseases, Murdoch University, Perth, Western Australia, Australia.
| | - Linda F Dawson
- Centre for Research on Chronic Pain and Inflammatory Diseases, Murdoch University, Perth, Western Australia, Australia
| | - Philip M Finch
- Centre for Research on Chronic Pain and Inflammatory Diseases, Murdoch University, Perth, Western Australia, Australia
| | - Eleanor S Drummond
- Centre for Research on Chronic Pain and Inflammatory Diseases, Murdoch University, Perth, Western Australia, Australia
| | - Fiona M Wood
- Burn Injury Research Unit, School of Surgery, University of Western Australia, Australia; The Fiona Wood Foundation, Perth, Western Australia, Australia; The Burns Service of Western Australia, WA Department of Health, Western Australia, Australia
| | - Mark W Fear
- Burn Injury Research Unit, School of Surgery, University of Western Australia, Australia; The Fiona Wood Foundation, Perth, Western Australia, Australia
| |
Collapse
|
112
|
Meeker R, Williams K. Dynamic nature of the p75 neurotrophin receptor in response to injury and disease. J Neuroimmune Pharmacol 2014; 9:615-28. [PMID: 25239528 DOI: 10.1007/s11481-014-9566-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 09/03/2014] [Indexed: 12/23/2022]
Abstract
Neurotrophins and their respective tropomyosin related kinase (Trk) receptors (TrkA, TrkB, and TrkC) and the p75 neurotrophin receptor (p75(NTR)) play a fundamental role in the development and maintenance of the nervous system making them important targets for treatment of neurodegenerative diseases. Whereas Trk receptors are directly activated by specific neurotrophins, the p75(NTR) is a multifunctional receptor that exerts its effects via heterodimeric interactions with TrkA, TrkB, TrkC, sortilin or the Nogo receptor to regulate a wide array of cellular functions. By partnering with different receptors the p75(NTR) regulates binding of mature versus pro-neurotrophins and activation of different signaling pathways with outcomes ranging from growth and survival to cell death. While the developmental downregulation of the p75(NTR) has raised questions regarding its role in the mature nervous system, recent data have revealed widespread expression of low levels, a role in synaptic plasticity and adult neurogenesis and upregulation in response to injury or disease. Studies are needed to better understand these processes, particularly in the damaged nervous system, but will be complicated by expression of p75(NTR) on immune cells including macrophages and microglia that are intimately involved in disease and repair processes. Recent approaches that regulate p75(NTR) function with small non-peptide ligands have demonstrated potent neuroprotection in models of injury and neurodegenerative diseases that highlight the importance of the p75(NTR) as a therapeutic target. Future studies hold the promise of revealing a wealth of information on the multifaceted actions of the p75(NTR) that will inform the design of new neurotrophin-based therapies.
Collapse
Affiliation(s)
- Rick Meeker
- Department of Neurology, University of North Carolina, CB #7025 6109F Neuroscience Research Building, 115 Mason Farm Road, Chapel Hill, NC, 27599, USA,
| | | |
Collapse
|