scholarly journals PDK1 is a negative regulator of axon regeneration

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.

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 Experimental Model Systems for Understanding Human Axonal Injury Responses

2021 ◽  
Vol 22 (2) ◽  
pp. 474
Author(s):  
Bohm Lee ◽  
Yongcheol Cho
Keyword(s):  
Nervous System ◽  
Neurological Disorders ◽  
Axon Regeneration ◽  
Experimental Models ◽  
Model Systems ◽  
The Central Nervous System ◽  
Experimental Model Systems ◽  
Do So

Neurons are structurally unique and have dendrites and axons that are vulnerable to injury. Some neurons in the peripheral nervous system (PNS) can regenerate their axons after injuries. However, most neurons in the central nervous system (CNS) fail to do so, resulting in irreversible neurological disorders. To understand the mechanisms of axon regeneration, various experimental models have been utilized in vivo and in vitro. Here, we collate the key experimental models that revealed the important mechanisms regulating axon regeneration and degeneration in different systems. We also discuss the advantages of experimenting with the rodent model, considering the application of these findings in understanding human diseases and for developing therapeutic methods.

scholarly journals mTORC1 is necessary but mTORC2 and GSK3β are inhibitory for AKT3-induced axon regeneration in the central nervous system

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Linqing Miao ◽  
Liu Yang ◽  
Haoliang Huang ◽  
Feisi Liang ◽  
Chen Ling ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Axon Regeneration ◽  
Nodal Point ◽  
Mtor Signaling ◽  
Negative Regulator ◽  
Molecular Dissection ◽  
Parallel Pathways ◽  
Downstream Effectors ◽  
The Central Nervous System

Injured mature CNS axons do not regenerate in mammals. Deletion of PTEN, the negative regulator of PI3K, induces CNS axon regeneration through the activation of PI3K-mTOR signaling. We have conducted an extensive molecular dissection of the cross-regulating mechanisms in axon regeneration that involve the downstream effectors of PI3K, AKT and the two mTOR complexes (mTORC1 and mTORC2). We found that the predominant AKT isoform in CNS, AKT3, induces much more robust axon regeneration than AKT1 and that activation of mTORC1 and inhibition of GSK3β are two critical parallel pathways for AKT-induced axon regeneration. Surprisingly, phosphorylation of T308 and S473 of AKT play opposite roles in GSK3β phosphorylation and inhibition, by which mTORC2 and pAKT-S473 negatively regulate axon regeneration. Thus, our study revealed a complex neuron-intrinsic balancing mechanism involving AKT as the nodal point of PI3K, mTORC1/2 and GSK3β that coordinates both positive and negative cues to regulate adult CNS axon regeneration.

Design, fabrication, and testing of a bioprinted nerve graft

2016 ◽  
Author(s):  
◽  
Christopher M. Owens
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Graft ◽  
Loss Of Function ◽  
Vitro Assay ◽  
Central Nervous System Damage ◽  
In Vivo Animal Model ◽  
The Central Nervous System

Injuries to nerves vary in their consequences, from weakened sensation and motor function to partial or complete paralysis. In the latter case, affecting about twenty thousand Americans yearly, the injury is debilitating and results in a significant decrease in quality of life. Currently there is no effective treatment for damage to the central nervous system, in particular the spinal cord. Compared to the injuries to the central nervous system, damage in the peripheral nerves, is more common, with about sixty thousand occurrences annually. The cost of associated surgical procedures and due to loss of function is in the billions. In this thesis we present work towards the construction and testing of a fully cellular, patented nerve graft, one amongst the first of its kind. For the fabrication of the graft we are the first to employ bioprinting (either implemented through a special purpose 3D bioprinter or manually), a novel tissue engineering method rapidly gaining acceptance and utility. We first review the status of bioprinting. We then detail the fabrication process. Next we report on the testing of the graft in an in vivo animal model through electrophysiology and histology. This is followed by the introduction of a novel in vitro model, aimed at providing a fast, inexpensive and reliable method to test engineered nerve grafts. We describe our work on the optimization of the in vitro assay and then the testing of the graft using the optimized assay. We conclude with a summary of our accomplishments and make suggestions for some exciting future applications of our approach.

scholarly journals 3D in vitro peripheral nervous system organoid using mouse primary dorsal root ganglion neurons and Schwann cells

IBRO Reports ◽  
2019 ◽  
Vol 6 ◽  
pp. S124
Author(s):  
Woon-Hae Kim ◽  
Hyun-Gyu Kang ◽  
Taehoon H. Kim ◽  
Yoon Jeong Mo ◽  
Yu Seon Kim ◽  
...  
Keyword(s):  
Nervous System ◽  
Dorsal Root Ganglion ◽  
Peripheral Nervous System ◽  
Schwann Cells ◽  
Dorsal Root ◽  
Dorsal Root Ganglion Neurons ◽  
Ganglion Neurons

Myo-inositol transport in the central nervous system

1975 ◽  
Vol 228 (5) ◽  
pp. 1510-1518 ◽  
Author(s):  
R Spector ◽  
AV Lorenzo
Keyword(s):  
Central Nervous System ◽  
Cerebrospinal Fluid ◽  
Nervous System ◽  
Choroid Plexus ◽  
Intraventricular Injection ◽  
Affinity Constant ◽  
Rapid Injection ◽  
The Central Nervous System

Free myo-inositol (inositol) transport into the cerebrospinal fluid (CSF), brain, and choroid plexus and out of the cerebrospinal fluid was measured in rabbits. In vivo, inositol transport from blood into choroid plexus, CSF, and brain was saturable with an apparent affinity constant (K-t) of approximately 0.1 mM. The relative turnover of free inositol in choroid plexus (16 percent/h) was higher than in CSF 4percent/h) and brain (0.3percent/h) when meausred by tissue penetration of tracer [3-H]-labeled inositol injected into blood. However, the passage of tracer inositol was not greater than the passage of mannitol into brain when measured 15 s after a rapid injection of inositol and mannitol into the left common carotid artery. From the CSF, the clearance of inositol relative to inulin was saturable after the intraventricular injection of various concentrations of inositol and inulin. Moreover, a portion of the inositol cleared from the CSF entered brain by a saturable mechanism. In vitro, choroid plexuses, isolated from rabbits and incubated in artificial CSF, accumulated [3-H-labeled myo-inositol against a concentration gradient by a specific, active, saturable process with a K-t of 0.2 mM inositol. These results were interpreted as showing that the entry of inositol into the central nervous system from blood is regulated by a saturable transport system, and that the locus of this system may be, in part, in the choroid plexus.

scholarly journals Characterization of More Selective Central Nervous System Nrf2-Activating Novel Vinyl Sulfoximine Compounds Compared to Dimethyl Fumarate

2020 ◽  
Vol 17 (3) ◽  
pp. 1142-1152 ◽  
Author(s):  
Karl E. Carlström ◽  
Praveen K. Chinthakindi ◽  
Belén Espinosa ◽  
Faiez Al Nimer ◽  
Elias S. J. Arnér ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
De Novo ◽  
Dimethyl Fumarate ◽  
The Novel ◽  
The Central Nervous System ◽  
Demyelinating Disorders ◽  
Target Effects

Abstract The Nrf2 transcription factor is a key regulator of redox reactions and considered the main target for the multiple sclerosis (MS) drug dimethyl fumarate (DMF). However, exploration of additional Nrf2-activating compounds is motivated, since DMF displays significant off-target effects and has a relatively poor penetrance to the central nervous system (CNS). We de novo synthesized eight vinyl sulfone and sulfoximine compounds (CH-1–CH-8) and evaluated their capacity to activate the transcription factors Nrf2, NFκB, and HIF1 in comparison with DMF using the pTRAF platform. The novel sulfoximine CH-3 was the most promising candidate and selected for further comparison in vivo and later an experimental model for traumatic brain injury (TBI). CH-3 and DMF displayed comparable capacity to activate Nrf2 and downstream transcripts in vitro, but with less off-target effects on HIF1 from CH-3. This was verified in cultured microglia and oligodendrocytes (OLs) and subsequently in vivo in rats. Following TBI, DMF lowered the number of leukocytes in blood and also decreased axonal degeneration. CH-3 preserved or increased the number of pre-myelinating OL. While both CH-3 and DMF activated Nrf2, CH-3 showed less off-target effects and displayed more selective OL associated effects. Further studies with Nrf2-acting compounds are promising candidates to explore potential myelin protective or regenerative effects in demyelinating disorders.

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