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

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.

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

10.1101/2021.05.24.445420 ◽

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.

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Complement Protein C1q Modulates Neurite Outgrowth In Vitro and Spinal Cord Axon Regeneration In Vivo

Journal of Neuroscience ◽

10.1523/jneurosci.4473-12.2015 ◽

2015 ◽

Vol 35 (10) ◽

pp. 4332-4349 ◽

Cited By ~ 23

Author(s):

S. L. Peterson ◽

H. X. Nguyen ◽

O. A. Mendez ◽

A. J. Anderson

Keyword(s):

Spinal Cord ◽

Neurite Outgrowth ◽

Axon Regeneration ◽

Complement Protein

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Transplantation of Neuregulin1-Overexpressing Bone Marrow Mesenchymal Cells Accelerates Motor Functional Recovery by Facilitating Neurite Outgrowth and Reducing Cell Apoptosis in Rat after Spinal Cord Injury

10.21203/rs.3.rs-67905/v1 ◽

2020 ◽

Author(s):

Geng Wu ◽

Herui Liu ◽

Mei Zhu ◽

Yang Wu ◽

Yunlong Bai ◽

...

Keyword(s):

Spinal Cord ◽

Bone Marrow ◽

Neurite Outgrowth ◽

Pc12 Cells ◽

Functional Recovery ◽

Cell Apoptosis ◽

Cord Injury ◽

Neuronal Chromatolysis

Abstract Background: Bone marrow mesenchymal stem cells (BMSCs) transplantation offers an attractive strategy for treating multiply neurological diseases. Neuregulin1 (NRG1) plays fundamental roles in nervous system development and nerve repair. In this study, we aimed to investigate whether transplantation of NRG1-overexpressing BMSCs could alleviate spinal cord injury (SCI), and to explore the possible underling mechanisms. Methods: In vitro, NRG1-overexpressing BMSCs were constructed via plasmid transfection, and co-cultured with PC12 cells subjected to oxygen-glucose deprivation (OGD). Neurite outgrowth, cell viability and apoptosis of PC12 cells were evaluated. In vivo, BMSCs, empty-vector BMSCs and NRG1-overexpressing BMSCs were transplanted respectively into rats with SCI. Rat locomotor functions, neuronal chromatolysis, neurite outgrowth and cell apoptosis were assessed respectively. Results: The results showed that NRG1-overexpressing BMSCs in vitro significantly expedited neurite growth, elevated growth-associated protein 43 expression, enhanced cell viability and rescued ODG-induced apoptosis in PC12 cells. In vivo, transplantation of NRG1-overexpressing BMSCs notably accelerated rat motor functional recovery, attenuated neuronal chromatolysis, promoted neurite outgrowth and reduced cell apoptosis after SCI. Moreover, NRG1-overexpressing BMSCs were also able to regulate apoptosis-related proteins expression after SCI. Conclusions: These findings demonstrate that NRG1-overexpressing BMSCs can accelerate motor functional recovery by facilitating neurite outgrowth and reducing cell apoptosis after SCI, suggesting that NRG1-overexpressing BMSCs may be a promising candidate for the treatment of SCI.

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PDK1 is a negative regulator of axon regeneration

Molecular Brain ◽

10.1186/s13041-021-00748-z ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Hyemin Kim ◽

Jinyoung Lee ◽

Yongcheol Cho

Keyword(s):

Nervous System ◽

Axon Regeneration ◽

Dorsal Root Ganglion Neurons ◽

Negative Regulator ◽

Protein Levels ◽

Adult Mice ◽

The Central Nervous System ◽

Ganglion Neurons

AbstractAxon regeneration in the central nervous system is inefficient. However, the neurons in the peripheral nervous system display robust regeneration after injury, indicating that axonal regeneration is differentially controlled under various conditions. To identify those molecules regulating axon regeneration, comparative analysis from dorsal root ganglion neurons at embryonic or adult stages is utilized, which reveals that PDK1 is functions as a negative regulator of axon regeneration. PDK1 is downregulated in embryonic neurons after axotomy. In contrast, sciatic nerve axotomy upregulated PDK1 at protein levels from adult mice. The knockdown of PDK1 or the chemical inhibition of PDK1 promotes axon regeneration in vitro and in vivo. Here we present PDK1 as a new player to negatively regulate axon regeneration and as a potential target in the development of therapeutic applications.

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Ligand-Induced GPR110 Activation Facilitates Axon Growth after Injury

International Journal of Molecular Sciences ◽

10.3390/ijms22073386 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3386

Author(s):

Heungsun Kwon ◽

Karl Kevala ◽

Hu Xin ◽

Samarjit Patnaik ◽

Juan Marugan ◽

...

Keyword(s):

Optic Nerve ◽

Neurite Outgrowth ◽

Nerve Injury ◽

Cortical Neurons ◽

Axon Growth ◽

Neurite Growth ◽

Nerve Crush ◽

Developing Neurons

Recovery from axonal injury is extremely difficult, especially for adult neurons. Here, we demonstrate that the activation of G-protein coupled receptor 110 (GPR110, ADGRF1) is a mechanism to stimulate axon growth after injury. N-docosahexaenoylethanolamine (synaptamide), an endogenous ligand of GPR110 that promotes neurite outgrowth and synaptogenesis in developing neurons, and a synthetic GPR110 ligand stimulated neurite growth in axotomized cortical neurons and in retinal explant cultures. Intravitreal injection of GPR110 ligands following optic nerve crush injury promoted axon extension in adult wild-type, but not in gpr110 knockout, mice. In vitro axotomy or in vivo optic nerve injury rapidly induced the neuronal expression of gpr110. Activating the developmental mechanism of neurite outgrowth by specifically targeting GPR110 that is upregulated upon injury may provide a novel strategy for stimulating axon growth after nerve injury in adults.

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

Experimental Neurology ◽

10.1016/j.expneurol.2017.11.011 ◽

2018 ◽

Vol 300 ◽

pp. 247-258 ◽

Cited By ~ 12

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

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

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.659783 ◽

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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Docosahexaenoic Acid-Loaded Polylactic Acid Core-Shell Nanofiber Membranes for Regenerative Medicine after Spinal Cord Injury: In Vitro and In Vivo Study

International Journal of Molecular Sciences ◽

10.3390/ijms21197031 ◽

2020 ◽

Vol 21 (19) ◽

pp. 7031

Author(s):

Zhuo-Hao Liu ◽

Yin-Cheng Huang ◽

Chang-Yi Kuo ◽

Chao-Ying Kuo ◽

Chieh-Yu Chin ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Docosahexaenoic Acid ◽

Neurite Outgrowth ◽

Polylactic Acid ◽

In Vivo Study ◽

Core Shell ◽

Cord Injury

Spinal cord injury (SCI) is associated with disability and a drastic decrease in quality of life for affected individuals. Previous studies support the idea that docosahexaenoic acid (DHA)-based pharmacological approach is a promising therapeutic strategy for the management of acute SCI. We postulated that a nanostructured material for controlled delivery of DHA at the lesion site may be well suited for this purpose. Toward this end, we prepare drug-loaded fibrous mats made of core-shell nanofibers by electrospinning, which contained a polylactic acid (PLA) shell for encapsulation of DHA within the core, for delivery of DHA in situ. In vitro study confirmed sustained DHA release from PLA/DHA core-shell nanofiber membrane (CSNM) for up to 36 days, which could significantly increase neurite outgrowth from primary cortical neurons in 3 days. This is supported by the upregulation of brain-derived neurotropic factor (BDNF) and neurotrophin-3 (NT-3) neural marker genes from qRT-PCR analysis. Most importantly, the sustained release of DHA could significantly increase the neurite outgrowth length from cortical neuron cells in 7 days when co-cultured with PLA/DHA CSNM, compared with cells cultured with 3 μM DHA. From in vivo study with a SCI model created in rats, implantation of PLA/DHA CSNM could significantly improve neurological functions revealed by behavior assessment in comparison with the control (no treatment) and the PLA CSNM groups. According to histological analysis, PLA/DHA CSNM also effectively reduced neuron loss and increased serotonergic nerve sprouting. Taken together, the PLA/DHA CSNM may provide a nanostructured drug delivery system for DHA and contribute to neuroprotection and promoting neuroplasticity change following SCI.

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Nitrous Oxide Impairs Axon Regeneration after Nervous System Injury in Male Rats

Anesthesiology ◽

10.1097/aln.0000000000002906 ◽

2019 ◽

Vol 131 (5) ◽

pp. 1063-1076

Author(s):

Krista J. Stewart ◽

Bermans J. Iskandar ◽

Brenton M. Meier ◽

Elias B. Rizk ◽

Nithya Hariharan ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Nervous System ◽

Nitrous Oxide ◽

Folic Acid ◽

Functional Recovery ◽

Axon Regeneration ◽

Retinal Ganglion ◽

Cord Injury

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Nitrous oxide can induce neurotoxicity. The authors hypothesized that exposure to nitrous oxide impairs axonal regeneration and functional recovery after central nervous system injury. Methods The consequences of single and serial in vivo nitrous oxide exposures on axon regeneration in four experimental male rat models of nervous system injury were measured: in vitro axon regeneration in cell culture after in vivo nitrous oxide administration, in vivo axon regeneration after sharp spinal cord injury, in vivo axon regeneration after sharp optic nerve injury, and in vivo functional recovery after blunt contusion spinal cord injury. Results In vitro axon regeneration 48 h after a single in vivo 70% N2O exposure is less than half that in the absence of nitrous oxide (mean ± SD, 478 ± 275 um; n = 48) versus 210 ± 152 um (n = 48; P < 0.0001). A single exposure to 80% N2O inhibits the beneficial effects of folic acid on in vivo axonal regeneration after sharp spinal cord injury (13.4 ± 7.1% regenerating neurons [n = 12] vs. 0.6 ± 0.7% regenerating neurons [n = 4], P = 0.004). Serial 80% N2O administration reverses the benefit of folic acid on in vivo retinal ganglion cell axon regeneration after sharp optic nerve injury (1277 ± 180 regenerating retinal ganglion cells [n = 7] vs. 895 ± 164 regenerating retinal ganglion cells [n = 7], P = 0.005). Serial 80% N2O exposures reverses the benefit of folic acid on in vivo functional recovery after blunt spinal cord contusion (estimate for fixed effects ± standard error of the estimate: folic acid 5.60 ± 0.54 [n = 9] vs. folic acid + 80% N2O 5.19 ± 0.62 [n = 7], P < 0.0001). Conclusions These data indicate that nitrous oxide can impair the ability of central nervous system neurons to regenerate axons after sharp and blunt trauma.

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B-RAF kinase drives developmental axon growth and promotes axon regeneration in the injured mature CNS

Journal of Experimental Medicine ◽

10.1084/jem.20131780 ◽

2014 ◽

Vol 211 (5) ◽

pp. 801-814 ◽

Cited By ~ 53

Author(s):

Kevin J. O’Donovan ◽

Kaijie Ma ◽

Hengchang Guo ◽

Chen Wang ◽

Fang Sun ◽

...

Keyword(s):

Optic Nerve ◽

Axon Regeneration ◽

Axon Growth ◽

Loss Of Function ◽

Pten Loss ◽

Raf Kinase ◽

Central Nervous Systems ◽

Neurotrophin Signaling ◽

Peripheral Sensory

Activation of intrinsic growth programs that promote developmental axon growth may also facilitate axon regeneration in injured adult neurons. Here, we demonstrate that conditional activation of B-RAF kinase alone in mouse embryonic neurons is sufficient to drive the growth of long-range peripheral sensory axon projections in vivo in the absence of upstream neurotrophin signaling. We further show that activated B-RAF signaling enables robust regenerative growth of sensory axons into the spinal cord after a dorsal root crush as well as substantial axon regrowth in the crush-lesioned optic nerve. Finally, the combination of B-RAF gain-of-function and PTEN loss-of-function promotes optic nerve axon extension beyond what would be predicted for a simple additive effect. We conclude that cell-intrinsic RAF signaling is a crucial pathway promoting developmental and regenerative axon growth in the peripheral and central nervous systems.

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