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Teixeira CA, Miranda CO, Sousa VF, Santos TE, Malheiro AR, Solomon M, Maegawa GH, Brites P, Sousa MM. Early axonal loss accompanied by impaired endocytosis, abnormal axonal transport, and decreased microtubule stability occur in the model of Krabbe's disease. Neurobiol Dis 2014; 66:92-103. [PMID: 24607884 PMCID: PMC4307018 DOI: 10.1016/j.nbd.2014.02.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 02/21/2014] [Accepted: 02/27/2014] [Indexed: 12/12/2022] Open
Abstract
In Krabbe's disease (KD), a leukodystrophy caused by β-galactosylceramidase deficiency, demyelination and a myelin-independent axonopathy contributes to the severe neuropathology. Beyond axonopathy, we show that in Twitcher mice, a model of KD, a decreased number of axons both in the PNS and in the CNS, and of neurons in dorsal root ganglia (DRG), occurred before the onset of demyelination. Despite the early axonal loss, and although in vitro Twitcher neurites degenerated over time, Twitcher DRG neurons displayed an initial neurite overgrowth and, following sciatic nerve injury, Twitcher axons were regeneration-competent, at a time point where axonopathy was already ongoing. Psychosine, the toxic substrate that accumulates in KD, induced lipid raft clustering. At the mechanistic level, TrkA recruitment to lipid rafts was dysregulated in Twitcher neurons, and defective activation of the ERK1/2 and AKT pathways was identified. Besides defective recruitment of signaling molecules to lipid rafts, the early steps of endocytosis and the transport of endocytic and synaptic vesicles were impaired in Twitcher DRG neurons. Defects in axonal transport, specifically in the retrograde component, correlated with decreased levels of dynein, abnormal levels of post-translational tubulin modifications and decreased microtubule stability. The identification of the axonal defects that precede demyelination in KD, together with the finding that Twitcher axons are regeneration-competent when axonopathy is already installed, opens new windows of action to effectively correct the neuropathology that characterizes this disorder.
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Affiliation(s)
- Carla Andreia Teixeira
- Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Catarina Oliveira Miranda
- Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Largo Prof. Abel Salazar, 2, 4099-003 Porto, Portugal
| | - Vera Filipe Sousa
- Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Largo Prof. Abel Salazar, 2, 4099-003 Porto, Portugal
| | - Telma Emanuela Santos
- Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Ana Rita Malheiro
- Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Melani Solomon
- McKusick-Nathans Institute of Genetic Medicine and Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Gustavo H Maegawa
- McKusick-Nathans Institute of Genetic Medicine and Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Pedro Brites
- Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
| | - Mónica Mendes Sousa
- Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
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Abstract
Structurally destabilizing mutations in acid beta-glucosidase (GCase) can result in Gaucher disease (GD). The iminosugar isofagomine (IFG), a competitive inhibitor and a potential pharmacological chaperone of GCase, is currently undergoing clinical evaluation for the treatment of GD. An X-ray crystallographic study of the GCase-IFG complex revealed a hydrogen bonding network between IFG and certain active site residues. It was suggested that this network may translate into greater global stability. Here it is demonstrated that IFG does increase the global stability of wild-type GCase, shifting its melting curve by approximately 15 degrees C and that it enhances mutant GCase activity in pre-treated N370S/N370S and F213I/L444P patient fibroblasts. Additionally, amide hydrogen/deuterium exchange mass spectroscopy (H/D-Ex) was employed to identify regions within GCase that undergo stabilization upon IFG-binding. H/D-Ex data indicate that the binding of IFG not only restricts the local protein dynamics of the active site, but also propagates this effect into surrounding regions.
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Affiliation(s)
- Gregory J Kornhaber
- ExSAR Corporation, 11 Deer Park Drive, Suite 103, Monmouth Junction, NJ 08852, USA
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Tropak MB, Kornhaber GJ, Rigat BA, Maegawa GH, Buttner JD, Blanchard JE, Murphy C, Tuske SJ, Coales SJ, Hamuro Y, Brown ED, Mahuran DJ. Identification of pharmacological chaperones for Gaucher disease and characterization of their effects on beta-glucocerebrosidase by hydrogen/deuterium exchange mass spectrometry. Chembiochem 2009; 9:2650-62. [PMID: 18972510 DOI: 10.1002/cbic.200800304] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Point mutations in beta-glucocerebrosidase (GCase) can result in a deficiency of both GCase activity and protein in lysosomes thereby causing Gaucher Disease (GD). Enzyme inhibitors such as isofagomine, acting as pharmacological chaperones (PCs), increase these levels by binding and stabilizing the native form of the enzyme in the endoplasmic reticulum (ER), and allow increased lysosomal transport of the enzyme. A high-throughput screen of the 50,000-compound Maybridge library identified two, non-carbohydrate-based inhibitory molecules, a 2,4-diamino-5-substituted quinazoline (IC(50) 5 microM) and a 5-substituted pyridinyl-2-furamide (IC(50) 8 microM). They raised the levels of functional GCase 1.5-2.5-fold in N370S or F213I GD fibroblasts. Immunofluorescence confirmed that treated GD fibroblasts had decreased levels of GCase in their ER and increased levels in lysosomes. Changes in protein dynamics, monitored by hydrogen/deuterium-exchange mass spectrometry, identified a domain III active-site loop (residues 243-249) as being significantly stabilized upon binding of isofagomine or either of these two new compounds; this suggests a common mechanism for PC enhancement of intracellular transport.
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Affiliation(s)
- Michael B Tropak
- Research Institute, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G1X8, Canada
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Tropak MB, Kornhaber GJ, Rigat BA, Maegawa GH, Buttner JD, Blanchard JE, Murphy C, Tuske SJ, Coales SJ, Hamuro Y, Brown ED, Mahuran DJ. Cover Picture: Identification of Pharmacological Chaperones for Gaucher Disease and Characterization of Their Effects on β-Glucocerebrosidase by Hydrogen/Deuterium Exchange Mass Spectrometry (ChemBioChem 16/2008). Chembiochem 2008. [DOI: 10.1002/cbic.200890061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Werneck LC, Scola RH, Maegawa GH, Werneck MC. Comparative analysis of PCR-deletion detection and immunohistochemistry in Brazilian Duchenne and Becker muscular dystrophy patients. Am J Med Genet 2001; 103:115-20. [PMID: 11568916 DOI: 10.1002/ajmg.1508] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We studied 48 patients with dystrophinopathies (29 Duchenne muscular dystrophy (DMD), 13 Becker muscular dystrophy (BMD), four possible carriers, one female with DMD, and one intermediate form, using polymerase chain reaction (PCR) analysis of muscle tissue for 20 exons and compared them with immunohistochemistry studies for dystrophin. Of these, 42 (87.5%) showed at least one intragenic deletion. Most of them (47.45%) involved exons 2 to 20. All BMD patients presented deletions on the dystrophin gene. The 29 patients with DMD showed abnormal dystrophin in immunohistochemistry studies, some with total absence (17/29), others with residual (3/29), and the remaining with scattered positive fiber (9/29). The majority of the 13 patients with BMD had abnormal immunohistochemistry studies with diffuse reduction in the majority of muscle fibers (10/13), a few with patch discontinuation in the sarcolemma (2/13), and one normal (1/13). The immunohistochemistry exam for dystrophin is still the gold-standard method for DMD/BMD diagnosis. An ethnic difference, the analysis of several exons, the sample size, and the use of muscle tissue could explain this high frequency of deletions in the dystrophin gene found in our cases.
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Affiliation(s)
- L C Werneck
- Neuromuscular Disorders Unit, Neurology Division, Internal Medicine Department, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba Brazil.
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Abstract
True neurogenic thoracic outlet syndrome is caused by compression of the lower trunk of the brachial plexus usually by a cervical rib, fibrous band or an elongated transverse process of C7. We describe two cases of female patients (23 and 19 years old) with pain in the right superior limb and progressive muscular weakness and atrophy of the intrinsic muscles of hand. Electrodiagnostic studies showed reduced amplitude of compound muscle action potential of median nerve and decreased amplitude of ulnar sensory nerve action potential. Motor and sensory nerve conduction velocities were normal in both patients. Needle electromyography were findings compatible with chronic denervation in the intrinsic muscles of the right hand of both patients. Radiological investigation showed cervical ribs in one case and elongated transverse process of C7 in the other. A discussion about the clinical and electrophysiological features and the treatment of the syndrome was performed.
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Affiliation(s)
- R H Scola
- Departamento de Clínica Médica, Hospital de Clínicas, Universidade Federal do Paraná (UFPR), Brasil.
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Scola RH, Werneck LC, Iwamoto FM, Cabral NL, Maegawa GH, Rogacheski E. [Ossification of the posterior longitudinal ligament in the cervical spine: case report]. Arq Neuropsiquiatr 1998; 56:480-5. [PMID: 9754433 DOI: 10.1590/s0004-282x1998000300021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ossification of the posterior longitudinal ligament (OPLL) is an uncommon cause of compressive myelopathy in the Caucasian population. A case of spastic paraparesis in a Caucasian man whose radiological investigation showed OPLL is presented. The radiographs of the cervical spine showed a strip of bony density posterior to the vertebral bodies, extending from C2 to T1. Computerized tomography (CT) and CT myelography showed OPLL at the same level. Magnetic resonance showed an area of increased signal on T2-weighted sequences at C7-T1 level suggestive of myelomalacia. The patient underwent an open-door laminoplasty (C2 to C7) with improvement of the paraparesis. OPLL should be included in the differential diagnosis of cervical myelopathy. It can be easily detected by plain radiographs and CT of the cervical spine. A review of the clinical and radiological features and the treatment of OPLL is presented.
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Affiliation(s)
- R H Scola
- Departamento de Clínica Médica, Hospital de Clínicas, Universidade Federal do Paraná (UFPR), Brasil.
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