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Khan S, Carrasco DI, Isaacson R, English AW. Proportions of four distinct classes of sensory neurons are retained even when axon regeneration is enhanced following peripheral nerve injury. Front Neuroanat 2023; 17:1303888. [PMID: 38020215 PMCID: PMC10657864 DOI: 10.3389/fnana.2023.1303888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Recovery from peripheral nerve injuries is poor because axon regeneration is slow and inefficient. Experimental therapies that increase signaling of neuronal brain-derived neurotrophic factor (BDNF) through its TrkB receptor or through its downstream effectors enhance axon regeneration, increasing the number of motor and sensory neurons whose axons successfully regenerate and reinnervate muscle targets. The goal of this study was to compare the proportions of four different classes of sensory (dorsal root ganglion, DRG) neurons that successfully reinnervate two different muscle targets in control mice and mice treated pharmacologically to enhance axon regeneration. Methods Following sciatic nerve transection and repair, C57BL/6 J mice were treated for 2 weeks, either with R13, a prodrug that releases the small molecule TrkB ligand, 7,8-dihydroxyflavone, with compound 11 (CP11), an inhibitor of asparaginyl endopeptidase (δ-secretase), or with a control vehicle. Four weeks after injury, different fluorescent retrograde tracers were injected into the gastrocnemius and tibialis anterior muscles to mark DRG neurons that had successfully reinnervated these muscles. Using immunofluorescence, retrogradely labeled DRG neurons also expressing markers of four different sensory neuronal classes were counted. Results and discussion Treatments with R13 or CP11 resulted in muscle reinnervation by many more DRG neurons than vehicletreated controls, but neurons expressing proteins associated with the different classes of DRG neurons studied were largely in the same proportions found in intact mice.
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Affiliation(s)
| | | | | | - Arthur W. English
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
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Isaacson RH, Carrasco DI, Holliday H, Kang SS, Khan S, Kim D, Liu X, Ye K, English AW. Treatments with the specific δ-secretase inhibitor, compound 11, promote the regeneration of motor and sensory axons after peripheral nerve injury. Eur J Neurosci 2023; 58:3555-3568. [PMID: 37608574 DOI: 10.1111/ejn.16126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/21/2023] [Accepted: 08/09/2023] [Indexed: 08/24/2023]
Abstract
Limited axon regeneration following peripheral nerve injury may be related to activation of the lysosomal protease, asparaginyl endopeptidase (AEP, δ-secretase) and its degradation of the microtubule associated protein, Tau. Activity of AEP was increased at the site of sciatic nerve transection and repair but blocked in mice treated systemically with a specific AEP inhibitor, compound 11 (CP11). Treatments with CP11 enhanced axon regeneration in vivo. Amplitudes of compound muscle action potentials recorded 4 weeks after nerve transection and repair and 2 weeks after daily treatments with CP11 were double those of vehicle-treated mice. At that time after injury, axons of significantly more motor and sensory neurons had regenerated successfully and reinnervated the tibialis anterior and gastrocnemius muscles in CP11-treated mice than vehicle-treated controls. In cultured adult dorsal root ganglion neurons derived from wild type mice that were treated in vitro for 24 h with CP11, neurites were nearly 50% longer than in vehicle-treated controls and similar to neurite lengths in cultures treated with the TrkB agonist, 7,8-dihydroxyflavone (7,8-DHF). Combined treatment with CP11 and 7,8-DHF did not enhance outgrowth more than treatments with either one alone. Enhanced neurite outgrowth produced by CP11 was found also in the presence of the TrkB inhibitor, ANA-12, indicating that the enhancement was independent of TrkB signalling. Longer neurites were found after CP11 treatment in both TrkB+ and TrkB- neurons. Delta secretase inhibition by CP11 is a treatment for peripheral nerve injury with great potential.
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Affiliation(s)
- Robin H Isaacson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Dario I Carrasco
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Hannah Holliday
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Seong Su Kang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Samia Khan
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - David Kim
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Xia Liu
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Keqiang Ye
- Faculty of Life and Health Sciences, and Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology (SIAT), Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Arthur W English
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
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Jin MY, Weaver TE, Farris A, Gupta M, Abd-Elsayed A. Neuromodulation for Peripheral Nerve Regeneration: Systematic Review of Mechanisms and In Vivo Highlights. Biomedicines 2023; 11:biomedicines11041145. [PMID: 37189763 DOI: 10.3390/biomedicines11041145] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 03/24/2023] [Accepted: 04/07/2023] [Indexed: 05/17/2023] Open
Abstract
While denervation can occur with aging, peripheral nerve injuries are debilitating and often leads to a loss of function and neuropathic pain. Although injured peripheral nerves can regenerate and reinnervate their targets, this process is slow and directionless. There is some evidence supporting the use of neuromodulation to enhance the regeneration of peripheral nerves. This systematic review reported on the underlying mechanisms that allow neuromodulation to aid peripheral nerve regeneration and highlighted important in vivo studies that demonstrate its efficacy. Studies were identified from PubMed (inception through September 2022) and the results were synthesized qualitatively. Included studies were required to contain content related to peripheral nerve regeneration and some form of neuromodulation. Studies reporting in vivo highlights were subject to a risk of bias assessment using the Cochrane Risk of Bias tool. The results of 52 studies indicate that neuromodulation enhances natural peripheral nerve regeneration processes, but still requires other interventions (e.g., conduits) to control the direction of reinnervation. Additional human studies are warranted to verify the applicability of animal studies and to determine how neuromodulation can be optimized for the greatest functional restoration.
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Affiliation(s)
- Max Y Jin
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Tristan E Weaver
- Department of Anesthesiology, The Ohio State University Wexner Medical Center, Columbus, OH 43214, USA
| | - Adam Farris
- Department of Anesthesiology, The Ohio State University Wexner Medical Center, Columbus, OH 43214, USA
| | - Mayank Gupta
- Kansas Pain Management & Neuroscience Research Center, Overland Park, KS 66210, USA
| | - Alaa Abd-Elsayed
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Tian T, Harris A, Owyoung J, SiMa H, Ward PJ. Conditioning electrical stimulation fails to enhance sympathetic axon regeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.03.527071. [PMID: 36778305 PMCID: PMC9915730 DOI: 10.1101/2023.02.03.527071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Peripheral nerve injuries are common, and there is a critical need for the development of novel therapeutics to complement surgical repair. Conditioning electrical stimulation (CES) is a novel variation to the well-studied perioperative electrical stimulation, both of which have displayed success in enhancing the regeneration of motor and sensory axons in an injured peripheral nerve. CES is a clinically attractive alternative not only because of its ability to be performed at the bedside prior to a scheduled nerve repair surgery, but it has also been shown to be superior to perioperative electrical stimulation in the enhancement of motor and sensory regeneration. However, the effects of CES on sympathetic regeneration are unknown. Therefore, we tested the effects of two clinically relevant CES paradigms on sympathetic axon regeneration and distal target reinnervation. Because of the long history of evidence for the enhancement of motor and sensory axons in response to electrical stimulation, we hypothesize that CES will also enhance sympathetic axon regeneration. Our results indicate that the growth of sympathetic axons is acutely inhibited by CES; however, at a longer survival time point post-injury, there is no difference between sham CES and the CES groups. There has been evidence to suggest that the growth of sympathetic axons is inhibited by a conditioning lesion, and that sympathetic axons may respond to electrical stimulation by sprouting rather than elongation. Our data indicate that sympathetic axons may retain some regenerative ability after CES, but no enhancement is exhibited, which may be accounted for by the inability of the current clinically relevant electrical stimulation paradigm to recruit the small-caliber sympathetic axons into activity. Further studies will be needed to optimize electrical stimulation parameters in order to enhance the regeneration of all neuron types.
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Solberg R, Lunde NN, Forbord KM, Okla M, Kassem M, Jafari A. The Mammalian Cysteine Protease Legumain in Health and Disease. Int J Mol Sci 2022; 23:ijms232415983. [PMID: 36555634 PMCID: PMC9788469 DOI: 10.3390/ijms232415983] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/05/2022] [Accepted: 12/10/2022] [Indexed: 12/23/2022] Open
Abstract
The cysteine protease legumain (also known as asparaginyl endopeptidase or δ-secretase) is the only known mammalian asparaginyl endopeptidase and is primarily localized to the endolysosomal system, although it is also found extracellularly as a secreted protein. Legumain is involved in the regulation of diverse biological processes and tissue homeostasis, and in the pathogenesis of various malignant and nonmalignant diseases. In addition to its proteolytic activity that leads to the degradation or activation of different substrates, legumain has also been shown to have a nonproteolytic ligase function. This review summarizes the current knowledge about legumain functions in health and disease, including kidney homeostasis, hematopoietic homeostasis, bone remodeling, cardiovascular and cerebrovascular diseases, fibrosis, aging and senescence, neurodegenerative diseases and cancer. In addition, this review addresses the effects of some marketed drugs on legumain. Expanding our knowledge on legumain will delineate the importance of this enzyme in regulating physiological processes and disease conditions.
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Affiliation(s)
- Rigmor Solberg
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, N-0316 Oslo, Norway
- Correspondence: (R.S.); (A.J.); Tel.: +47-22-857-514 (R.S.); +45-35-337-423 (A.J.)
| | - Ngoc Nguyen Lunde
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, N-0316 Oslo, Norway
| | - Karl Martin Forbord
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, N-0316 Oslo, Norway
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
| | - Meshail Okla
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 12372, Saudi Arabia
| | - Moustapha Kassem
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
- Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Abbas Jafari
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
- Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Correspondence: (R.S.); (A.J.); Tel.: +47-22-857-514 (R.S.); +45-35-337-423 (A.J.)
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Song XJ, Zhou HY, Sun YY, Huang HC. Phosphorylation and Glycosylation of Amyloid-β Protein Precursor: The Relationship to Trafficking and Cleavage in Alzheimer's Disease. J Alzheimers Dis 2021; 84:937-957. [PMID: 34602469 DOI: 10.3233/jad-210337] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder in the central nervous system, and this disease is characterized by extracellular senile plaques and intracellular neurofibrillary tangles. Amyloid-β (Aβ) peptide is the main constituent of senile plaques, and this peptide is derived from the amyloid-β protein precursor (AβPP) through the successive cleaving by β-site AβPP-cleavage enzyme 1 (BACE1) and γ-secretase. AβPP undergoes the progress of post-translational modifications, such as phosphorylation and glycosylation, which might affect the trafficking and the cleavage of AβPP. In the recent years, about 10 phosphorylation sites of AβPP were identified, and they play complex roles in glycosylation modification and cleavage of AβPP. In this article, we introduced the transport and the cleavage pathways of AβPP, then summarized the phosphorylation and glycosylation sites of AβPP, and further discussed the links and relationship between phosphorylation and glycosylation on the pathways of AβPP trafficking and cleavage in order to provide theoretical basis for AD research.
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Affiliation(s)
- Xi-Jun Song
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, China.,Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing, China
| | - He-Yan Zhou
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, China.,Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing, China
| | - Yu-Ying Sun
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, China.,Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing, China
| | - Han-Chang Huang
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing, China.,Research Institute of Functional Factors and Brain Science, Beijing Union University, Beijing, China
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