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Petrie CN, Smithson LJ, Crotty AM, Michalski B, Fahnestock M, Kawaja MD. Overexpression of nerve growth factor by murine smooth muscle cells: Role of the p75 neurotrophin receptor on sympathetic and sensory sprouting. J Comp Neurol 2013; 521:2621-43. [DOI: 10.1002/cne.23302] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 11/06/2012] [Accepted: 01/03/2013] [Indexed: 01/06/2023]
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Willand MP, Holmes M, Bain JR, Fahnestock M, De Bruin H. Electrical muscle stimulation after immediate nerve repair reduces muscle atrophy without affecting reinnervation. Muscle Nerve 2013; 48:219-25. [PMID: 23637030 DOI: 10.1002/mus.23726] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2012] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Electrical stimulation of denervated muscle has been shown to minimize atrophy and fibrosis and increase force in animal and human models. However, electrical stimulation after nerve repair is controversial due to questions of efficacy. METHODS Using a rat model, we investigated the efficacy of short-term electrical muscle stimulation for increasing reinnervation and preventing muscle atrophy. After tibial nerve transection and immediate repair with the fibular nerve, 1 month of electrical stimulation was applied 5 days/week for 1 hour to the gastrocnemius muscle via implanted electrodes. RESULTS After 2 months of further recovery without stimulation, muscle weights, twitch forces, and type I fiber areas were significantly greater in stimulated animals than in repaired controls without stimulation. Motor unit size and numbers were not different between the 2 groups. CONCLUSIONS Short-term electrical muscle stimulation after nerve repair significantly reduces muscle atrophy and does not affect motor reinnervation.
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Ubhi K, Rockenstein E, Vazquez-Roque R, Mante M, Inglis C, Patrick C, Adame A, Fahnestock M, Doppler E, Novak P, Moessler H, Masliah E. Cerebrolysin modulates pronerve growth factor/nerve growth factor ratio and ameliorates the cholinergic deficit in a transgenic model of Alzheimer's disease. J Neurosci Res 2013; 91:167-77. [PMID: 23152192 DOI: 10.1002/jnr.23142] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 08/19/2012] [Accepted: 08/21/2012] [Indexed: 11/09/2022]
Abstract
Alzheimer's disease (AD) is characterized by degeneration of neocortex, limbic system, and basal forebrain, accompanied by accumulation of amyloid-β and tangle formation. Cerebrolysin (CBL), a peptide mixture with neurotrophic-like effects, is reported to improve cognition and activities of daily living in patients with AD. Likewise, CBL reduces synaptic and behavioral deficits in transgenic (tg) mice overexpressing the human amyloid precursor protein (hAPP). The neuroprotective effects of CBL may involve multiple mechanisms, including signaling regulation, control of APP metabolism, and expression of neurotrophic factors. We investigate the effects of CBL in the hAPP tg model of AD on levels of neurotrophic factors, including pro-nerve growth factor (NGF), NGF, brain-derived neurotrophic factor (BDNF), neurotropin (NT)-3, NT4, and ciliary neurotrophic factor (CNTF). Immunoblot analysis demonstrated that levels of pro-NGF were increased in saline-treated hAPP tg mice. In contrast, CBL-treated hAPP tg mice showed levels of pro-NGF comparable to control and increased levels of mature NGF. Consistently with these results, immunohistochemical analysis demonstrated increased NGF immunoreactivity in the hippocampus of CBL-treated hAPP tg mice. Protein levels of other neurotrophic factors, including BDNF, NT3, NT4, and CNTF, were unchanged. mRNA levels of NGF and other neurotrophins were also unchanged. Analysis of neurotrophin receptors showed preservation of the levels of TrKA and p75(NTR) immunoreactivity per cell in the nucleus basalis. Cholinergic cells in the nucleus basalis were reduced in the saline-treated hAPP tg mice, and treatment with CBL reduced these cholinergic deficits. These results suggest that the neurotrophic effects of CBL might involve modulation of the pro-NGF/NGF balance and a concomitant protection of cholinergic neurons.
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Willand MP, Holmes M, Bain JR, Fahnestock M, de Bruin H. Determining the effects of electrical stimulation on functional recovery of denervated rat gastrocnemius muscle using motor unit number estimation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:1977-80. [PMID: 22254721 DOI: 10.1109/iembs.2011.6090557] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The use of electrical muscle stimulation to treat denervated muscle prior to delayed reinnervation has been widely debated. There is evidence showing both positive and negative results following different protocols of electrical stimulation. In this study we investigated the role electrical stimulation has on muscle reinnervation following immediate and delayed nerve repair using motor unit estimation techniques. Rat gastrocnemius muscle was denervated and repaired using the peroneal nerve either immediately or following three-months with and without electrical stimulation. Motor unit counts, average motor unit sizes, and maximum compound action potentials were measured three-months following peroneal nerve repair. Motor unit counts in animals that were denervated and stimulated were significantly higher than those that were denervated and not stimulated. Both average motor unit sizes and maximum compound action potentials showed no significant differences between denervated and denervated-stimulated animals. These results provide evidence that electrical stimulation prior to delayed nerve repair increases muscle receptivity to regenerating axons and may be a worthwhile treatment for peripheral nerve injuries.
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Kawaja MD, Smithson LJ, Elliott J, Trinh G, Crotty AM, Michalski B, Fahnestock M. Nerve growth factor promoter activity revealed in mice expressing enhanced green fluorescent protein. J Comp Neurol 2011; 519:2522-45. [PMID: 21456011 DOI: 10.1002/cne.22629] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nerve growth factor (NGF) and its precursor proNGF are perhaps the best described growth factors of the mammalian nervous system. There remains, however, a paucity of information regarding the precise cellular sites of proNGF/NGF synthesis. Here we report the generation of transgenic mice in which the NGF promoter controls the ectopic synthesis of enhanced green fluorescent protein (EGFP). These transgenic mice provide an unprecedented resolution of both neural cells (e.g., neocortical and hippocampal neurons) and non-neural cells (e.g., renal interstitial cells and thymic reticular cells) that display NGF promoter activity from postnatal development to adulthood. Moreover, the transgene is inducible by injury. At 2 days after sciatic nerve ligation, a robust population of EGFP-positive cells is seen in the proximal nerve stump. These transgenic mice offer novel insights into the cellular sites of NGF promoter activity and can be used as models for investigating the regulation of proNGF/NGF expression after injury.
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Bercik P, Park AJ, Sinclair D, Khoshdel A, Lu J, Huang X, Deng Y, Blennerhassett PA, Fahnestock M, Moine D, Berger B, Huizinga JD, Kunze W, McLean PG, Bergonzelli GE, Collins SM, Verdu EF. The anxiolytic effect of Bifidobacterium longum NCC3001 involves vagal pathways for gut-brain communication. NEUROGASTROENTEROLOGY AND MOTILITY : THE OFFICIAL JOURNAL OF THE EUROPEAN GASTROINTESTINAL MOTILITY SOCIETY 2011. [PMID: 21988661 DOI: 10.1111/j.1365-2982.2011.01796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND The probiotic Bifidobacterium longum NCC3001 normalizes anxiety-like behavior and hippocampal brain derived neurotrophic factor (BDNF) in mice with infectious colitis. Using a model of chemical colitis we test whether the anxiolytic effect of B. longum involves vagal integrity, and changes in neural cell function. Methods Mice received dextran sodium sulfate (DSS, 3%) in drinking water during three 1-week cycles. Bifidobacterium longum or placebo were gavaged daily during the last cycle. Some mice underwent subdiaphragmatic vagotomy. Behavior was assessed by step-down test, inflammation by myeloperoxidase (MPO) activity and histology. BDNF mRNA was measured in neuroblastoma SH-SY5Y cells after incubation with sera from B. longum- or placebo-treated mice. The effect of B. longum on myenteric neuron excitability was measured using intracellular microelectrodes. KEY RESULTS Chronic colitis was associated with anxiety-like behavior, which was absent in previously vagotomized mice. B. longum normalized behavior but had no effect on MPO activity or histological scores. Its anxiolytic effect was absent in mice with established anxiety that were vagotomized before the third DSS cycle. B. longum metabolites did not affect BDNF mRNA expression in SH-SY5Y cells but decreased excitability of enteric neurons. CONCLUSIONS & INFERENCES In this colitis model, anxiety-like behavior is vagally mediated. The anxiolytic effect of B. longum requires vagal integrity but does not involve gut immuno-modulation or production of BDNF by neuronal cells. As B. longum decreases excitability of enteric neurons, it may signal to the central nervous system by activating vagal pathways at the level of the enteric nervous system.
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Fahnestock M. Brain-derived neurotrophic factor: the link between amyloid-β and memory loss. FUTURE NEUROLOGY 2011. [DOI: 10.2217/fnl.11.44] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is a critical molecule for learning and memory. Brain BDNF levels correlate with cognitive status. BDNF is downregulated in Alzheimer’s disease, in age-related cognitive impairment and in a variety of other neurodegenerative and psychiatric disorders exhibiting cognitive deficits. BDNF is downregulated in the Alzheimer’s disease brain by soluble, aggregated amyloid-β, acting via a pathway involving the transcription factor cAMP response element binding protein, which activates BDNF transcript IV. The complete pathway by which BDNF is downregulated is still unclear, and the diagnostic and therapeutic use of BDNF in neurodegenerative disease has not yet been exploited.
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Willand MP, Lopez JP, de Bruin H, Fahnestock M, Holmes M, Bain JR. A New System and Paradigm for Chronic Stimulation of Denervated Rat Muscle. J Med Biol Eng 2011; 31:87-92. [PMID: 22973186 DOI: 10.5405/jmbe.828] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Traditionally, animal studies employing electrical stimulation for conditioning denervated muscle rely on 24-hour-based stimulation paradigms, most employing implantable stimulators. While these stimulators provide the necessary current to cause muscular contraction, they have problems with battery life, programmability, and long-term robustness. Continuous 24-hour stimulation, while shown to be effective in animals, is not easily translatable to a clinical setting. It is also difficult to evaluate animal comfort and muscular contraction throughout a 24-hour period. We have developed a system and stimulation paradigm that can stimulate up to five animals at one time for one hour per day. The constant current stimulator is a USB-powered device that can, under computer control, output trains of pulses with selectable shapes, widths, durations and repetition rates. It is an external device with no implantable parts in the animal except for the stimulating electrodes. We tested the system on two groups of rats with denervated gastrocnemius muscles. One group was stimulated using a one-hour-per-day, 5-days-per-week stimulation paradigm for one month, while the other group had electrodes implanted but received no stimulation. Muscle weight and twitch force were significantly larger in the stimulated group than the non-stimulated group. Presently, we are using the stimulator to investigate electrical stimulation coupled with other therapeutic interventions that can minimize functional deficits after peripheral nerve injuries.
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Perez SE, He B, Muhammad N, Oh KJ, Fahnestock M, Ikonomovic MD, Mufson EJ. Cholinotrophic basal forebrain system alterations in 3xTg-AD transgenic mice. Neurobiol Dis 2010; 41:338-52. [PMID: 20937383 DOI: 10.1016/j.nbd.2010.10.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 09/07/2010] [Accepted: 10/02/2010] [Indexed: 12/29/2022] Open
Abstract
The cholinotrophic system, which is dependent upon nerve growth factor and its receptors for survival, is selectively vulnerable in Alzheimer's disease (AD). But, virtually nothing is known about how this deficit develops in relation to the hallmark lesions of this disease, amyloid plaques and tau containing neurofibrillary tangles. The vast majority of transgenic models of AD used to evaluate the effect of beta amyloid (Aβ) deposition upon the cholinotrophic system over-express the amyloid precursor protein (APP). However, nothing is known about how this system is affected in triple transgenic (3xTg)-AD mice, an AD animal model displaying Aβ plaque- and tangle-like pathology in the cortex and hippocampus, which receive extensive cholinergic innervation. We performed a detailed morphological and biochemical characterization of the cholinotrophic system in young (2-4 months), middle-aged (13-15 months) and old (18-20 months) 3xTg-AD mice. Cholinergic neuritic swellings increased in number and size with age, and were more conspicuous in the hippocampal-subicular complex in aged female than in 3xTg-AD male mice. Stereological analysis revealed a reduction in choline acetyltransferase (ChAT) positive cells in the medial septum/vertical limb of the diagonal band of Broca in aged 3xTg-AD mice. ChAT enzyme activity levels decreased significantly in the hippocampus of middle-aged 3xTg-AD mice compared to age-matched non-transgenic (or wild type) mice. ProNGF protein levels increased in the cortex of aged 3xTg-AD mice, whereas TrkA protein levels were reduced in a gender-dependent manner in aged mutant mice. In contrast, p75(NTR) protein cortical levels were stable but increased in the hippocampus of aged 3xTg-AD mice. These data demonstrate that cholinotrophic alterations in 3xTg-AD mice are age- and gender-dependent and more pronounced in the hippocampus, a structure more severely affected by Aβ plaque pathology.
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Francis BM, Kim J, Barakat ME, Fraenkl S, Yücel YH, Peng S, Michalski B, Fahnestock M, McLaurin J, Mount HTJ. Object recognition memory and BDNF expression are reduced in young TgCRND8 mice. Neurobiol Aging 2010; 33:555-63. [PMID: 20447730 DOI: 10.1016/j.neurobiolaging.2010.04.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 03/22/2010] [Accepted: 04/05/2010] [Indexed: 01/17/2023]
Abstract
The TgCRND8 mouse model of Alzheimer's disease exhibits progressive cortical and hippocampal β-amyloid accumulation, resulting in plaque pathology and spatial memory impairment by 3 months of age. We tested whether TgCRND8 cognitive function is disrupted prior to the appearance of macroscopic plaques in an object recognition task. We found profound deficits in 8-week-old mice. Animals this age were not impaired on the Morris water maze task. TgCRND8 and littermate controls did not differ in their duration of object exploration or optokinetic responses. Thus, visual and motor dysfunction did not confound the phenotype. Object memory deficits point to the frontal cortex and hippocampus as early targets of functional disruption. Indeed, we observed altered levels of brain-derived neurotrophic factor (BDNF) messenger ribonucleic acid (mRNA) in these brain regions of preplaque TgCRND8 mice. Our findings suggest that object recognition provides an early index of cognitive impairment associated with amyloid exposure and reduced brain-derived neurotrophic factor expression in the TgCRND8 mouse.
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Fahnestock M, Marchese M, Head E, Pop V, Michalski B, Milgram W, Cotman C. BDNF increases with behavioral enrichment and an antioxidant diet in the aged dog. J Vet Behav 2010. [DOI: 10.1016/j.jveb.2009.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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63
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Fahnestock M, Ioannou MS, Masoudi R. The biological activity of proNGF is determined by the relative levels of TrkA and p75NTR receptors. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1010.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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64
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Amundson JM, Fahnestock M, Truffer M, Brown J, Lüthi MP, Motyka RJ. Ice mélange dynamics and implications for terminus stability, Jakobshavn Isbræ, Greenland. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jf001405] [Citation(s) in RCA: 258] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Masoudi R, Ioannou MS, Coughlin MD, Pagadala P, Neet KE, Clewes O, Allen SJ, Dawbarn D, Fahnestock M. Biological activity of nerve growth factor precursor is dependent upon relative levels of its receptors. J Biol Chem 2009; 284:18424-33. [PMID: 19389705 PMCID: PMC2709390 DOI: 10.1074/jbc.m109.007104] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Indexed: 01/19/2023] Open
Abstract
Nerve growth factor (NGF) is produced as a precursor called pro-nerve growth factor (proNGF), which is secreted by many tissues and is the predominant form of NGF in the central nervous system. In Alzheimer disease brain, cholinergic neurons degenerate and can no longer transport NGF as efficiently, leading to an increase in untransported NGF in the target tissue. The protein that accumulates in the target tissue is proNGF, not the mature form. The role of this precursor is controversial, and both neurotrophic and apoptotic activities have been reported for recombinant proNGFs. Differences in the protein structures, protein expression systems, methods used for protein purification, and methods used for bioassay may affect the activity of these proteins. Here, we show that proNGF is neurotrophic regardless of mutations or tags, and no matter how it is purified or in which system it is expressed. However, although proNGF is neurotrophic under our assay conditions for primary sympathetic neurons and for pheochromocytoma (PC12) cells, it is apoptotic for unprimed PC12 cells when they are deprived of serum. The ratio of tropomyosin-related kinase A to p75 neurotrophin receptor is low in unprimed PC12 cells compared with primed PC12 cells and sympathetic neurons, altering the balance of proNGF-induced signaling to favor apoptosis. We conclude that the relative level of proNGF receptors determines whether this precursor exhibits neurotrophic or apoptotic activity.
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Bain JR, Fahnestock M. Erratum. J Neurosurg 2009; 110:197. [DOI: 10.3171/jns.2009.110.1.197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Bain JR, Fahnestock M, Hason Y, Quartly C, Veltri K. Erratum. J Neurosurg 2009. [DOI: 10.3171/jns.2009.110.1.0197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Bain JR, Hason Y, Veltri K, Fahnestock M, Quartly C. Clinical application of sensory protection of denervated muscle. J Neurosurg 2008; 109:955-61. [PMID: 18976091 DOI: 10.3171/jns/2008/109/11/0955] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Following proximal peripheral nerve injury, motor recovery is often poor due to prolonged muscle denervation and loss of regenerative potential. The transfer of a sensory nerve to denervated muscle results in improved functional recovery in experimental models. The authors here report the first clinical case of sensory protection. Following a total hip arthroplasty, this patient experienced a complete sciatic nerve palsy with no recovery at 3 months postsurgery and profound denervation confirmed electrodiagnostically. He underwent simultaneous neurolysis of the sciatic nerve and saphenous nerve transfers to the tibialis anterior branch of the peroneal nerve and gastrocnemius branch from the tibial nerve. He noted an early proprioceptive response. Electromyography demonstrated initially selective amelioration of denervation potentials followed by improved motor recovery in sensory protected muscles only. The patient reported clinically significant functional improvements in activities of daily living. The authors hypothesize that the presence of a sensory nerve during muscle denervation can improve functional motor recovery.
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Fahnestock M, Peng S, Marchese M, Delvaux ER, Coleman PD. P1‐345: BDNF mRNA levels are decreased in peripheral blood samples from subjects with Alzheimer's disease. Alzheimers Dement 2008. [DOI: 10.1016/j.jalz.2008.05.926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Hines J, Groll M, Fahnestock M, Crews CM. Proteasome inhibition by fellutamide B induces nerve growth factor synthesis. CHEMISTRY & BIOLOGY 2008; 15:501-12. [PMID: 18482702 PMCID: PMC2485210 DOI: 10.1016/j.chembiol.2008.03.020] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 03/20/2008] [Accepted: 03/25/2008] [Indexed: 01/26/2023]
Abstract
Neurotrophic small molecules have the potential to aid in the treatment of neuronal injury and neurodegenerative diseases. The natural product fellutamide B, originally isolated from Penicillium fellutanum, potently induces nerve growth factor (NGF) release from fibroblasts and glial-derived cells, although the mechanism for this neurotrophic activity has not been elucidated. Here, we report that fellutamide B potently inhibits proteasome catalytic activity. High-resolution structural information obtained from cocrystallization of the 20S proteasome reveals novel aspects regarding beta-subunit binding and adduct formation by fellutamide B to inhibit their hydrolytic activity. We demonstrate that fellutamide B and other proteasome inhibitors increased NGF gene transcription via a cis-acting element (or elements) in the promoter. These results demonstrate an unrecognized connection between proteasome inhibition and NGF production, suggesting a possible new strategy in the development of neurotrophic agents.
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Michalski B, Bain JR, Fahnestock M. Long-term changes in neurotrophic factor expression in distal nerve stump following denervation and reinnervation with motor or sensory nerve. J Neurochem 2008; 105:1244-52. [PMID: 18194437 DOI: 10.1111/j.1471-4159.2008.05224.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Several factors have been proposed to account for poor motor recovery after prolonged denervation, including motor neuron cell death and incomplete or poor regeneration of motor fibers into the muscle. Both may result from failure of the muscle and the distal motor nerve stump to continue expression of neurotrophic factors following delayed muscle reinnervation. This study investigated whether regenerating motor or sensory axons modulate distal nerve neurotrophic factor expression. We found that transected distal tibial nerve up-regulated brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) mRNA, down-regulated neurotrophin-3 and ciliary neurotrophic factor mRNA, and that although these levels returned to normal with regeneration, the chronically denervated distal nerve stump continued to express these neurotrophic factors for at least 6 months following injury. A sensory nerve (the cutaneous saphenous nerve) sutured to distal tibial nerve lowered injury-induced BDNF and GDNF mRNA levels in distal stump, but repair with a mixed nerve (peroneal, containing muscle and cutaneous axons) was more effective. Repair with sensory or mixed nerves did not affect nerve growth factor or neurotrophin-3 expression. Thus, distal nerve contributed to a neurotrophic environment for nerve regeneration for at least 6 months, and sensory nerve repair helped normalize distal nerve neurotrophic factor mRNA expression following denervation. Furthermore, as BDNF and GDNF levels in distal stump increased following denervation and returned to control levels following reinnervation, their levels serve as markers for the status of regeneration by either motor or sensory nerve.
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Mufson EJ, Counts SE, Fahnestock M, Ginsberg SD. Cholinotrophic Molecular Substrates of Mild Cognitive Impairment in the Elderly. Curr Alzheimer Res 2007; 4:340-50. [PMID: 17908035 DOI: 10.2174/156720507781788855] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholinergic nucleus basalis (NB) neurons provide the major cholinergic innervation to the cortical mantle, are selectively vulnerable in late stage Alzheimer's disease (AD) and require the neurotrophin, nerve growth factor (NGF) and its receptors (TrkA and p75(NTR)), for their survival. The molecular events underlying the demise of these neurons in AD were investigated using tissue harvested from participants in a longitudinal clinical pathological study of aging and AD who agreed to an annual clinical evaluation providing a categorization of no cognitive impairment (NCI), mild cognitive impairment (MCI) or AD and postmortem brain donation. Although the number of choline acetyltransferase (ChAT)-positive neurons was unchanged, TrkA and p75(NTR) receptor-containing neurons, which co-localize with ChAT, were significantly reduced in the NB of subjects with MCI and AD compared to those with NCI. These observations indicate a phenotypic down-regulation rather than frank NB neuronal degeneration in MCI. Expression profiling of single cholinergic NB neurons revealed TrkA but not p75(NTR) mRNA is reduced in MCI, suggesting that decreased neurotrophin responsiveness may be an early biomarker for AD. The NGF precursor molecule, proNGF, is increased in the cortex in MCI and AD. Since proNGF accumulates in the presence of reduced cortical TrkA and sustained levels of p75(NTR), a shift in the balance between cell survival and death molecules may occur in prodromal AD. Coincident with these phenomena, brain derived neurotrophic factor (BDNF) and its precursor molecule, proBDNF, are reduced in the MCI cortex, potentially depriving CBF neurons of additional trophic factor support. Moreover, there is a shift in the ratio of 3 repeat tau to 4 repeat tau gene expression, whereas total tau message is stable in NB neurons during the disease process. These data suggest there is a shift in cholinotrophic molecular events in MCI and early AD which may lead to cell dysfunction and eventual cell death over the course of the disease. These findings support the concept that from a neurotrophic pathobiologic perspective, MCI is already early AD.
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Hulbe C, Fahnestock M. Century-scale discharge stagnation and reactivation of the Ross ice streams, West Antarctica. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jf000603] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Garzon DJ, Fahnestock M. Oligomeric amyloid decreases basal levels of brain-derived neurotrophic factor (BDNF) mRNA via specific downregulation of BDNF transcripts IV and V in differentiated human neuroblastoma cells. J Neurosci 2007; 27:2628-35. [PMID: 17344400 PMCID: PMC6672502 DOI: 10.1523/jneurosci.5053-06.2007] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Alzheimer's disease (AD) is a senile dementia characterized by amyloid plaques, neurofibrillary tangles, and synaptic and cell loss. The "amyloid cascade" hypothesis suggests that amyloid-beta (Abeta), the peptide deposited as amyloid plaques, is the primary insult in AD. However, debate continues over the mechanism of Abeta toxicity and whether fibrillar or oligomeric Abeta is the active species of the peptide that ultimately causes the synaptic loss and dementia associated with AD. Brain-derived neurotrophic factor (BDNF) is required for survival and function of cells compromised in AD. Decreased BDNF causes defects in long-term potentiation and memory and correlates with cognitive decline. We previously demonstrated that BDNF reduction occurs early in the course of AD, suggesting that decreased BDNF may promote neuronal dysfunction in AD. We also demonstrated that three of seven human BDNF transcripts are specifically downregulated in AD. What pathological feature(s) of AD leads to the decreased BDNF is unknown. In this study, we administered both fibrillar and oligomeric conformations of Abeta(1-42) to differentiated SH-SY5Y, a human neuroblastoma cell line, and measured both phosphorylated cAMP response element-binding protein (CREB), a regulator of BDNF transcription, and BDNF total mRNA. We found that oligomeric but not fibrillar preparations of Abeta(1-42) significantly decrease both phosphorylated CREB and total BDNF mRNA. Furthermore, oligomeric Abeta(1-42) decreases BDNF transcripts IV and V in these cells, demonstrating that Abeta(1-42) downregulates the major BDNF transcript decreased in vivo in the AD brain. Thus, oligomeric Abeta(1-42) could compromise neuronal function, causing memory loss and cognitive dysfunction by downregulation of BDNF in AD.
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Buttigieg H, Kawaja MD, Fahnestock M. Neurotrophic activity of proNGF in vivo. Exp Neurol 2007; 204:832-5. [PMID: 17270174 DOI: 10.1016/j.expneurol.2006.12.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 12/12/2006] [Accepted: 12/14/2006] [Indexed: 01/19/2023]
Abstract
Ectopic expression of nerve growth factor (NGF) in transgenic mice results in the directional growth of sympathetic and/or sensory fibers. For instance, mice that over-express NGF under the control of the glial fibrillary acidic protein (GFAP) promoter exhibit robust axonal sprouting into the cerebellum, with no apparent loss of neurons in peripheral ganglia. Given the disagreement in the literature over whether pro-NGF exerts neurotrophic or apoptotic effects, we assessed the relative levels of proNGF and mature NGF in the cerebella of these transgenic mice. Blinded western blot analyses revealed that proNGF was the major species in both transgenic and wild type mice, with very low levels of mature NGF expression. While transgenic mice displayed significantly higher levels of cerebellar proNGF protein as compared to wild type mice, both strains possessed comparable levels of mature NGF. These data reveal that the ectopic expression of NGF in the cerebellum results in an increase in proNGF rather than mature NGF levels. Together with the robust axonal growth and lack of neuronal death in the ganglia in these animals, our results are clearly consistent with proNGF exhibiting neurotrophic activity in vivo.
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