scholarly journals Injury-free priming: induction of Primary Afferent Collateral Sprouting in uninjured sensory neurons in vivo primes them for enhanced axon outgrowth in vitro

2018 ◽  
Author(s):  
Sara Soleman ◽  
Jeffrey C. Petruska ◽  
Lawrence D.F. Moon
Keyword(s):  
Axon Regeneration ◽  
Axonal Injury ◽  
Axon Growth ◽  
Drg Neurons ◽  
Primary Afferent ◽  
Collateral Sprouting ◽  
Axon Elongation ◽  
Defined Media

AbstractPrior “conditioning” nerve lesions can prime DRG neurons for enhanced axon regeneration. Here, we tested the hypothesis that adult DRG neurons can be primed for axon elongation in vitro without axonal injury by prior induction of Primary Afferent Collateral Sprouting (PACS) in vivo. Thoracic cutaneous nerves (T9, T10, T12, T13 but not T11) were transected to create zones of denervated skin. Neurons from the uninjured T11 DRG underwent PACS within the skin, as demonstrated by the expansion of its zones responsive to pinch up to 14 days. At 7 or 14 days after induction of collateral sprouting, DRG neurons were dissociated and cultured for 18 hours in defined media lacking neurotrophins and growth factors. Neurons from the uninjured T11 DRG had longer mean neurite lengths than neurons from naïve DRG. A larger proportion of neurons from the uninjured T11 DRG showed an elongating or arborizing phenotype than neurons from naïve DRG. Transcriptomic analysis of the uninjured T11 DRG and denervated/reinnervated skin reveal regulation of receptor/ligand systems and regulators of growth during collateral sprouting. For example, the glial cell-derived neurotrophic family ligands Artemin and Persephin were upregulated in denervated skin after 7 and/or 14 days. We suggest that extracellular cues in denervated skin modify the intrinsic growth program of uninjured DRG neurons that enhances their ability to elongate or arborize even after explantation. Collectively, these data confirm that induction of collateral sprouting does not induce an injury response yet primes many of these uninjured neurons for in vitro axon growth.

scholarly journals Chronic neuronal activation increases dynamic microtubules to enhance functional axon regeneration after dorsal root crush injury

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Di Wu ◽  
Ying Jin ◽  
Tatiana M. Shapiro ◽  
Abhishek Hinduja ◽  
Peter W. Baas ◽  
...  
Keyword(s):  
Dorsal Root ◽  
Axon Regeneration ◽  
Axon Growth ◽  
Crush Injury ◽  
Neuronal Activation ◽  
Drg Neurons ◽  
Root Entry Zone ◽  
The Status

AbstractAfter a dorsal root crush injury, centrally-projecting sensory axons fail to regenerate across the dorsal root entry zone (DREZ) to extend into the spinal cord. We find that chemogenetic activation of adult dorsal root ganglion (DRG) neurons improves axon growth on an in vitro model of the inhibitory environment after injury. Moreover, repeated bouts of daily chemogenetic activation of adult DRG neurons for 12 weeks post-crush in vivo enhances axon regeneration across a chondroitinase-digested DREZ into spinal gray matter, where the regenerating axons form functional synapses and mediate behavioral recovery in a sensorimotor task. Neuronal activation-mediated axon extension is dependent upon changes in the status of tubulin post-translational modifications indicative of highly dynamic microtubules (as opposed to stable microtubules) within the distal axon, illuminating a novel mechanism underlying stimulation-mediated axon growth. We have identified an effective combinatory strategy to promote functionally-relevant axon regeneration of adult neurons into the CNS after injury.

Essential role of heparan sulfates in axon navigation and targeting in the developing visual system

Development ◽  
1997 ◽  
Vol 124 (12) ◽  
pp. 2421-2430 ◽  
Author(s):  
A. Walz ◽  
S. McFarlane ◽  
Y.G. Brickman ◽  
V. Nurcombe ◽  
P.F. Bartlett ◽  
...  
Keyword(s):  
Visual System ◽  
Core Protein ◽  
Optic Tract ◽  
Axon Growth ◽  
Axon Elongation ◽  
Axon Extension ◽  
Heparan Sulfates

Heparan sulfate (HS) is abundant in the developing brain and is a required co-factor for many types of fibroblast growth factor (FGF) signaling in vitro. We report that some HSs, when added exogenously to the developing Xenopus optic pathway, severely disrupt target recognition causing axons from the retina to bypass their primary target, the optic tectum. Significantly, HS sidechains from a neuroepithelial perlecan variant that preferentially bind FGF-2, HS(FGF-2), cause aberrant targeting, whereas those that preferentially bind FGF-1 do not. Charge-matched fragments of HS(FGF-2) show that the mistargeting activity associates with the FGF-binding fragments. Heparitinase removal of native HSs at the beginning of optic tract formation retards retinal axon elongation; addition of FGF-2 restores axon extension but axons lose directionality. Late HS removal, after axons have extended through the tract, elicits a tectal bypass phenotype indicating a growth promoting and guidance function for native HSs. Our results demonstrate that different HS sidechains from the same core protein differentially affect axon growth in vivo, possibly due to their distinct FGF-binding preferences, and suggest that growth factors and HSs are important partners in regulating axon growth and guidance in the developing visual system.

scholarly journals N6-methyladenine DNA demethylase ALKBH1 regulates mammalian axon regeneration

2020 ◽  
Author(s):  
Qiao Li ◽  
Cheng Qian ◽  
Harry Feng ◽  
Tyger Lin ◽  
Ying Huang ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Neuronal Development ◽  
Axon Regeneration ◽  
Physiological Function ◽  
Axon Growth ◽  
Epigenetic Mechanism ◽  
Sensory Axon ◽  
Functional Roles

AbstractRecent studies have shown that DNA N6-methyladenine (N6-mA) modification is emerging to be a novel and important epigenetic regulator of mammalian gene transcription. Several studies demonstrated DNA N6-mA in human or rodents was regulated by methyltransferase N6AMT1 and demethylase ALKBH1. Moreover, studies in mouse brain or human glioblastoma cells showed that reduced level of N6-mA or higher level of ALKBH1 was correlated with up regulated levels of genes associated with neuronal development. We thus investigated the functional roles of ALKBH1 in sensory axon regeneration. Our results showed that ALKBH1 regulated the level of N6-mA in sensory neurons, and upon peripheral nerve injury ALKBH1 was up regulated in mouse sensory neurons. Functionally, knocking down ALKBH1 in sensory neurons resulted in reduced axon regeneration in vitro and in vivo, which could be rescued by simultaneously knocking down N6AMT1. Moreover, knocking down ALKBH1 led to decreased levels of many neurodevelopment regulatory genes, including neuritin that is well known to enhance axon growth and regeneration. Our study not only revealed a novel physiological function of DNA N6-mA, but also identified a new epigenetic mechanism regulating mammalian axon regeneration.Significance StatementThe study demonstrated that DNA N6-methyladenine (N6-mA) modification played important roles in regulation of sensory axon regeneration, likely through controlling the expression of neurodevelopmental associated genes. The results will add new evidence about the physiological function of DNA N6-mA and its regulatory demethylase ALKBH1 in neurons.

scholarly journals Overexpression of Reticulon 3 enhances CNS axon regeneration and functional recovery after injury

2021 ◽  
Author(s):  
Zubair Ahmed ◽  
Sharif Alhajlah ◽  
Adam Thompson
Keyword(s):  
Spinal Cord ◽  
Optic Nerve ◽  
Neurite Outgrowth ◽  
Functional Recovery ◽  
Axon Regeneration ◽  
Axon Growth ◽  
Dorsal Root Ganglion Neurons ◽  
Ganglion Neurons

CNS neurons are generally incapable of regenerating their axons after injury due to several intrinsic and extrinsic factors, including the presence of axon growth inhibitory molecules. One such potent inhibitor of CNS axon regeneration is Reticulon (RTN) 4 or Nogo-66. Here, we focused on RTN3 as its contribution in CNS axon regeneration is currently unknown. We found that RTN3 expression correlated with an axon regenerative phenotype in dorsal root ganglion neurons (DRGN) after injury to the dorsal columns, a model of spinal cord injury. Overexpression of RTN3 promoted disinhibited DRGN neurite outgrowth in vitro and dorsal column axon regeneration/sprouting and electrophysiological, sensory and locomotor functional recovery after injury in vivo. Knockdown of protrudin however, ablated RTN3-enhanced neurite outgrowth/axon regeneration in vitro and in vivo. Moreover, overexpression of RTN3 in a second model of CNS injury, the optic nerve crush injury model, enhanced retinal ganglion cell (RGC) survival, disinhibited neurite outgrowth in vitro and survival and axon regeneration in vivo, an effect that was also dependent on protrudin. These results demonstrate that RTN3 enhances neurite outgrowth/axon regeneration in a protrudin-dependent manner after both spinal cord and optic nerve injury.

scholarly journals Overexpression of Reticulon 3 Enhances CNS Axon Regeneration and Functional Recovery after Traumatic Injury

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 2015
Author(s):  
Sharif Alhajlah ◽  
Adam M Thompson ◽  
Zubair Ahmed
Keyword(s):  
Spinal Cord ◽  
Optic Nerve ◽  
Neurite Outgrowth ◽  
Functional Recovery ◽  
Axon Regeneration ◽  
Axon Growth ◽  
Dorsal Root Ganglion Neurons ◽  
Ganglion Neurons

CNS neurons are generally incapable of regenerating their axons after injury due to several intrinsic and extrinsic factors, including the presence of axon growth inhibitory molecules. One such potent inhibitor of CNS axon regeneration is Reticulon (RTN) 4 or Nogo-A. Here, we focused on RTN3 as its contribution to CNS axon regeneration is currently unknown. We found that RTN3 expression correlated with an axon regenerative phenotype in dorsal root ganglion neurons (DRGN) after injury to the dorsal columns, a well-characterised model of spinal cord injury. Overexpression of RTN3 promoted disinhibited DRGN neurite outgrowth in vitro and dorsal column axon regeneration/sprouting and electrophysiological, sensory and locomotor functional recovery after injury in vivo. Knockdown of protrudin, however, ablated RTN3-enhanced neurite outgrowth/axon regeneration in vitro and in vivo. Moreover, overexpression of RTN3 in a second model of CNS injury, the optic nerve crush injury model, enhanced retinal ganglion cell (RGC) survival, disinhibited neurite outgrowth in vitro and survival and axon regeneration in vivo, an effect that was also dependent on protrudin. These results demonstrate that RTN3 enhances neurite outgrowth/axon regeneration in a protrudin-dependent manner after both spinal cord and optic nerve injury.

scholarly journals Transcriptional Profiling of Porcine Blastocysts Produced In Vitro in a Chemically Defined Culture Medium

Animals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1414
Author(s):  
Josep M. Cambra ◽  
Emilio A. Martinez ◽  
Heriberto Rodriguez-Martinez ◽  
Maria A. Gil ◽  
Cristina Cuello
Keyword(s):  
Culture Medium ◽  
Embryo Quality ◽  
Transcriptional Profiling ◽  
Defined Medium ◽  
Platelet Factor ◽  
Defined Media ◽  
Defined Culture ◽  
The Impact

The development of chemically defined media is a growing trend in in vitro embryo production (IVP). Recently, traditional undefined culture medium with bovine serum albumin (BSA) has been successfully replaced by a chemically defined medium using substances with embryotrophic properties such as platelet factor 4 (PF4). Although the use of this medium sustains IVP, the impact of defined media on the embryonic transcriptome has not been fully elucidated. This study analyzed the transcriptome of porcine IVP blastocysts, cultured in defined (PF4 group) and undefined media (BSA group) by microarrays. In vivo-derived blastocysts (IVV group) were used as a standard of maximum embryo quality. The results showed no differentially expressed genes (DEG) between the PF4 and BSA groups. However, a total of 2780 and 2577 DEGs were detected when comparing the PF4 or the BSA group with the IVV group, respectively. Most of these genes were common in both in vitro groups (2132) and present in some enriched pathways, such as cell cycle, lysosome and/or metabolic pathways. These results show that IVP conditions strongly affect embryo transcriptome and that the defined culture medium with PF4 is a guaranteed replacement for traditional culture with BSA.

Continuation of fast axonal transport in regenerating axons in vitro

1979 ◽  
Vol 57 (11) ◽  
pp. 1251-1255
Author(s):  
M. A. Bisby ◽  
C. E. Hilton
Keyword(s):  
Sciatic Nerve ◽  
Vagus Nerve ◽  
Axonal Transport ◽  
Nerve Injury ◽  
Axon Regeneration ◽  
Free Medium ◽  
Fast Axonal Transport ◽  
Sensory Axons

A previous study by McLean and co-workers reported that regenerating axons of the rabbit vagus nerve were unable to sustain axonal transport in vitro for several months after nerve injury. In contrast, we found that sensory axons of the rat sciatic nerve were able to transport 3H-labeled protein into their regenerating portions distal to the site of injury within a week after injury when placed in vitro. Transport in vitro was not significantly less than transport in axons maintained in vivo for the same period. Transport occurred in the medium that was used by the McLean group, but was significantly reduced in calcium-free medium. When axon regeneration was delared, only small amounts of activity were present in the nerve distal to the site of injury, showing that labeled protein normally present in that part of the nerve was associated with axons and was not a result of local precursor uptake by nonneural elements in the sciatic nerve. We were not able to explain the failure of McLean and co-workers to demonstrate transport in vitro in regenerating vagus nerve, but we conclude that there is no general peculiarity of growing axons that makes them unable to sustain transport in vitro.

scholarly journals Neurofascin as a novel target for autoantibody-mediated axonal injury

2007 ◽  
Vol 204 (10) ◽  
pp. 2363-2372 ◽  
Author(s):  
Emily K. Mathey ◽  
Tobias Derfuss ◽  
Maria K. Storch ◽  
Kieran R. Williams ◽  
Kimberly Hales ◽  
...  
Keyword(s):  
Axonal Injury ◽  
Dependent Manner ◽  
Nodes Of Ranvier ◽  
Native Form ◽  
Neuronal Protein ◽  
Axonal Pathology ◽  
Immune Mediated ◽  
Novel Target

Axonal injury is considered the major cause of disability in patients with multiple sclerosis (MS), but the underlying effector mechanisms are poorly understood. Starting with a proteomics-based approach, we identified neurofascin-specific autoantibodies in patients with MS. These autoantibodies recognize the native form of the extracellular domains of both neurofascin 186 (NF186), a neuronal protein concentrated in myelinated fibers at nodes of Ranvier, and NF155, the oligodendrocyte-specific isoform of neurofascin. Our in vitro studies with hippocampal slice cultures indicate that neurofascin antibodies inhibit axonal conduction in a complement-dependent manner. To evaluate whether circulating antineurofascin antibodies mediate a pathogenic effect in vivo, we cotransferred these antibodies with myelin oligodendrocyte glycoprotein–specific encephalitogenic T cells to mimic the inflammatory pathology of MS and breach the blood–brain barrier. In this animal model, antibodies to neurofascin selectively targeted nodes of Ranvier, resulting in deposition of complement, axonal injury, and disease exacerbation. Collectively, these results identify a novel mechanism of immune-mediated axonal injury that can contribute to axonal pathology in MS.

scholarly journals Depolarization and electrical stimulation enhance in vitro and in vivo sensory axon growth after spinal cord injury

2018 ◽  
Vol 300 ◽  
pp. 247-258 ◽  
Author(s):  
Ioana Goganau ◽  
Beatrice Sandner ◽  
Norbert Weidner ◽  
Karim Fouad ◽  
Armin Blesch
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Electrical Stimulation ◽  
Axon Growth ◽  
Sensory Axon ◽  
Cord Injury

scholarly journals Exosome-Mediated Delivery of the Neuroprotective Peptide PACAP38 Promotes Retinal Ganglion Cell Survival and Axon Regeneration in Rats With Traumatic Optic Neuropathy

2021 ◽  
Vol 9 ◽  
Author(s):  
Tian Wang ◽  
Yiming Li ◽  
Miao Guo ◽  
Xue Dong ◽  
Mengyu Liao ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Ganglion Cell ◽  
Retinal Ganglion Cell ◽  
Optic Neuropathy ◽  
Axon Regeneration ◽  
Retinal Ganglion ◽  
Traumatic Optic Neuropathy ◽  
Fiber Layer

Traumatic optic neuropathy (TON) refers to optic nerve damage caused by trauma, leading to partial or complete loss of vision. The primary treatment options, such as hormonal therapy and surgery, have limited efficacy. Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38), a functional endogenous neuroprotective peptide, has emerged as a promising therapeutic agent. In this study, we used rat retinal ganglion cell (RGC) exosomes as nanosized vesicles for the delivery of PACAP38 loaded via the exosomal anchor peptide CP05 (EXOPACAP38). EXOPACAP38 showed greater uptake efficiency in vitro and in vivo than PACAP38. The results showed that EXOPACAP38 significantly enhanced the RGC survival rate and retinal nerve fiber layer thickness in a rat TON model. Moreover, EXOPACAP38 significantly promoted axon regeneration and optic nerve function after injury. These findings indicate that EXOPACAP38 can be used as a treatment option and may have therapeutic implications for patients with TON.

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