The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Fengquan Zhou - One of the best experts on this subject based on the ideXlab platform.
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time course analysis of sensory Axon regeneration in vivo by directly tracing regenerating Axons
Neural Regeneration Research, 2020Co-Authors: Yiwen Hu, Runshan Duan, Shuguang Yang, Fengquan Zhou, Ruiying WangAbstract:Most current studies quantify Axon regeneration by immunostaining regeneration-associated proteins, representing indirect measurement of Axon lengths from both sensory neurons in the dorsal root ganglia and motor neurons in the spinal cord. Our recently developed method of in vivo electroporation of plasmid DNA encoding for enhanced green fluorescent protein into adult sensory neurons in the dorsal root ganglia provides a way to directly and specifically measure regenerating sensory Axon lengths in whole-mount nerves. A mouse model of sciatic nerve compression was established by squeezing the sciatic nerve with tweezers. Plasmid DNA carrying enhanced green fluorescent protein was transfected by ipsilateral dorsal root ganglion electroporation 2 or 3 days before injury. Fluorescence distribution of dorsal root or sciatic nerve was observed by confocal microscopy. At 12 and 18 hours, and 1, 2, 3, 4, 5, and 6 days of injury, lengths of regenerated Axons after sciatic nerve compression were measured using green fluorescence images. Apoptosis-related protein caspase-3 expression in dorsal root ganglia was determined by western blot assay. We found that in vivo electroporation did not affect caspase-3 expression in dorsal root ganglia. Dorsal root ganglia and sciatic nerves were successfully removed and subjected to a rapid tissue clearing technique. Neuronal soma in dorsal root ganglia expressing enhanced green fluorescent protein or fluorescent dye-labeled microRNAs were imaged after tissue clearing. The results facilitate direct time course analysis of peripheral nerve Axon regeneration. This study was approved by the Institutional Animal Care and Use Committee of Guilin Medical University, China (approval No. GLMC201503010) on March 7, 2014.
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telomerase reverse transcriptase and p53 regulate mammalian peripheral nervous system and cns Axon regeneration downstream of c myc
The Journal of Neuroscience, 2019Co-Authors: Weihua Wang, Zongping Luo, Changmei Liu, Lei Yang, Jianquan Chen, Bin Meng, Huilin Yang, Fengquan ZhouAbstract:Although several genes have been identified to promote Axon regeneration in the CNS, our understanding of the molecular mechanisms by which mammalian Axon regeneration is regulated is still limited and fragmented. Here by using female mouse sensory Axon and optic nerve regeneration as model systems, we reveal an unexpected role of telomerase reverse transcriptase (TERT) in regulation of Axon regeneration. We also provide evidence that TERT and p53 act downstream of c-Myc to control sensory Axon regeneration. More importantly, overexpression of p53 in sensory neurons and retinal ganglion cells is sufficient to promote sensory Axon and optic never regeneration, respectively. The study reveals a novel c-Myc-TERT-p53 signaling pathway, expanding horizons for novel approaches promoting CNS Axon regeneration.SIGNIFICANCE STATEMENT Despite significant progress during the past decade, our understanding of the molecular mechanisms by which mammalian CNS Axon regeneration is regulated is still fragmented. By using sensory Axon and optic nerve regeneration as model systems, the study revealed an unexpected role of telomerase reverse transcriptase (TERT) in regulation of Axon regeneration. The results also delineated a c-Myc-TERT-p53 pathway in controlling Axon growth. Last, our results demonstrated that p53 alone was sufficient to promote sensory Axon and optic nerve regeneration in vivo Collectively, the study not only revealed a new mechanisms underlying mammalian Axon regeneration, but also expanded the pool of potential targets that can be manipulated to enhance CNS Axon regeneration.
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knocking out non muscle myosin ii in retinal ganglion cells promotes long distance optic nerve regeneration
bioRxiv, 2019Co-Authors: Xuewei Wang, Shuguang Yang, Chi Zhang, Y Zhang, Binbin Yang, Yi Lan Weng, Guo Li Ming, Anish R Kosanam, Fengquan ZhouAbstract:Summary In addition to changed gene expression, pathological cytoskeletal dynamics in the Axon is another key intrinsic barrier for Axon regeneration in the central nervous system (CNS). Here we showed that knocking out myosin IIA/B in retinal ganglion cells alone was sufficient to induce marked and sustained optic nerve regeneration. Combined Lin28 overexpression and myosin IIA/B knockout led to remarkable synergistic promoting effect and long-distance Axon regeneration. Immunostaining, RNA-seq and western blot analyses revealed that myosin II deletion did not affect known Axon regeneration signaling pathways or the expression of regeneration associated genes. Instead, it abolished the retraction bulb formation and significantly enhanced the Axon extension efficiency. The study provided clear and strong evidence that directly targeting neuronal cytoskeleton was sufficient to induce strong CNS Axon regeneration, and combining gene expression in the soma and modified cytoskeletal dynamics in the Axon was an optimal approach for long-distance CNS Axon regeneration.
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the telomerase reverse transcriptase tert and p53 regulate mammalian pns and cns Axon regeneration downstream of c myc
bioRxiv, 2019Co-Authors: Weihua Wang, Zongping Luo, Changmei Liu, Lei Yang, Jianquan Chen, Bin Meng, Huilin Yang, Fengquan ZhouAbstract:Summary Although several genes have been identified to promote Axon regeneration in the central nervous system, our understanding of the molecular mechanisms by which mammalian Axon regeneration is regulated is still limited and fragmented. Here by using sensory Axon and optic nerve regeneration as model systems, we revealed an unexpected role of telomerase reverse transcriptase (TERT) in regulation of Axon regeneration. We also provided strong evidence that TERT and p53 acted downstream of c-Myc to control sensory Axon regeneration. More importantly, overexpression of p53 in sensory neurons and retinal ganglion cells (RGCs) was sufficient to promote sensory Axon and optic never regeneration, respectively. The study revealed a novel c-Myc-TERT-p53 signaling pathway, expanding horizons for novel approaches promoting CNS Axon regeneration.
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gsk3 controls Axon growth via clasp mediated regulation of growth cone microtubules
Genes & Development, 2011Co-Authors: Eun Mi Hur, Byoung Dae Lee, Seong Jin Kim, Fengquan ZhouAbstract:Suppression of glycogen synthase kinase 3 (GSK3) activity in neurons yields pleiotropic outcomes, causing both Axon growth promotion and inhibition. Previous studies have suggested that specific GSK3 substrates, such as adenomatous polyposis coli (APC) and collapsin response mediator protein 2 (CRMP2), support Axon growth by regulating the stability of Axonal microtubules (MTs), but the substrate(s) and mechanisms conveying Axon growth inhibition remain elusive. Here we show that CLIP (cytoplasmic linker protein)-associated protein (CLASP), originally identified as a MT plus end-binding protein, displays both plus end-binding and lattice-binding activities in nerve growth cones, and reveal that the two MT-binding activities regulate Axon growth in an opposing manner: The lattice-binding activity mediates Axon growth inhibition induced by suppression of GSK3 activity via preventing MT protrusion into the growth cone periphery, whereas the plus end-binding property supports Axon extension via stabilizing the growing ends of Axonal MTs. We propose a model in which CLASP transduces GSK3 activity levels to differentially control Axon growth by coordinating the stability and configuration of growth cone MTs.
Kenji Sobue - One of the best experts on this subject based on the ideXlab platform.
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caldesmon regulates Axon extension through interaction with myosin ii
Journal of Biological Chemistry, 2012Co-Authors: Tsuyoshi Morita, Taira Mayanagi, Kenji SobueAbstract:To begin the process of forming neural circuits, new neurons first establish their polarity and extend their Axon. Axon extension is guided and regulated by highly coordinated cytoskeletal dynamics. Here we demonstrate that in hippocampal neurons, the actin-binding protein caldesmon accumulates in distal Axons, and its N-terminal interaction with myosin II enhances Axon extension. In cortical neural progenitor cells, caldesmon knockdown suppresses Axon extension and neuronal polarity. These results indicate that caldesmon is an important regulator of Axon development.
Alvaro Sagasti - One of the best experts on this subject based on the ideXlab platform.
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hydrogen peroxide promotes injury induced peripheral sensory Axon regeneration in the zebrafish skin
PLOS Biology, 2011Co-Authors: Sandra Rieger, Alvaro SagastiAbstract:Functional recovery from cutaneous injury requires not only the healing and regeneration of skin cells but also reinnervation of the skin by somatosensory peripheral Axon endings. To investigate how sensory Axon regeneration and wound healing are coordinated, we amputated the caudal fins of zebrafish larvae and imaged somatosensory Axon behavior. Fin amputation strongly promoted the regeneration of nearby sensory Axons, an effect that could be mimicked by ablating a few keratinocytes anywhere in the body. Since injury produces the reactive oxygen species hydrogen peroxide (H2O2) near wounds, we tested whether H2O2 influences cutaneous Axon regeneration. Exposure of zebrafish larvae to sublethal levels of exogenous H2O2 promoted growth of severed Axons in the absence of keratinocyte injury, and inhibiting H2O2 production blocked the Axon growth-promoting effects of fin amputation and keratinocyte ablation. Thus, H2O2 signaling helps coordinate wound healing with peripheral sensory Axon reinnervation of the skin.
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wallerian degeneration of zebrafish trigeminal Axons in the skin is required for regeneration and developmental pruning
Development, 2010Co-Authors: Seanna M Martin, Georgeann S Obrien, Carlos Porteracailliau, Alvaro SagastiAbstract:Fragments of injured Axons that detach from their cell body break down by the molecularly regulated process of Wallerian degeneration (WD). Although WD resembles local Axon degeneration, a common mechanism for refining neuronal structure, several previously examined instances of developmental pruning were unaffected by WD pathways. We used laser axotomy and time-lapse confocal imaging to characterize and compare peripheral sensory Axon WD and developmental pruning in live zebrafish larvae. Detached fragments of single injured Axon arbors underwent three stereotyped phases of WD: a lag phase, a fragmentation phase and clearance. The lag phase was developmentally regulated, becoming shorter as embryos aged, while the length of the clearance phase increased with the amount of Axon debris. Both cell-specific inhibition of ubiquitylation and overexpression of the Wallerian degeneration slow protein (WldS) lengthened the lag phase dramatically, but neither affected fragmentation. Persistent WldS-expressing Axon fragments directly repelled regenerating Axon branches of their parent arbor, similar to self-repulsion among sister branches of intact arbors. Expression of WldS also disrupted naturally occurring local Axon pruning and Axon degeneration in spontaneously dying trigeminal neurons: although pieces of WldS-expressing Axons were pruned, and some WldS-expressing cells still died during development, in both cases detached Axon fragments failed to degenerate. We propose that spontaneously pruned fragments of peripheral sensory Axons must be removed by a WD-like mechanism to permit efficient innervation of the epidermis.
Kei Ito - One of the best experts on this subject based on the ideXlab platform.
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engulfing action of glial cells is required for programmed Axon pruning during drosophila metamorphosis
Current Biology, 2004Co-Authors: Takeshi Awasaki, Kei ItoAbstract:Abstract Background: Axon pruning is involved in establishment and maintenance of functional neural circuits. During metamorphosis of Drosophila , selective pruning of larval Axons is developmentally regulated by ecdysone and caused by local Axon degeneration. Previous studies have revealed intrinsic molecular and cellular mechanisms that trigger this pruning process, but how pruning is accomplished remains essentially unknown. Results: Detailed analysis of morphological changes in the Axon branches of Drosophila mushroom body (MB) neurons revealed that during early pupal stages, clusters of neighboring varicosities, each of which belongs to different Axons, disappear simultaneously shortly before the onset of local Axon degeneration. At this stage, bundles of Axon branches are infiltrated by the processes of surrounding glia. These processes engulf clusters of varicosities and accumulate intracellular degradative compartments. Selective inhibition of cellular functions, including endocytosis, in glial cells via the temperature-sensitive allele of shibire both suppresses glial infiltration and varicosity elimination and induces a severe delay in Axon pruning. Selective inhibition of ecdysone receptors in the MB neurons severely suppressed not only Axon pruning but also the infiltration and engulfing action of the surrounding glia. Conclusions: These findings strongly suggest that glial cells are extrinsically activated by ecdysone-stimulated MB neurons. These glial cells infiltrate the mass of Axon branches to eliminate varicosities and break down Axon branches actively rather than just scavenging already-degraded debris. We therefore propose that neuron-glia interaction is essential for the precisely coordinated Axon-pruning process during Drosophila metamorphosis.
Carlos A. Saura - One of the best experts on this subject based on the ideXlab platform.
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presenilin γ secretase dependent epha3 processing mediates Axon elongation through non muscle myosin iia
eLife, 2019Co-Authors: Miriam Javiertorrent, Sergi Marco, Daniel Rocandio, Peter W. Janes, Martin Lackmann, Joaquim Egea, Maria Ponsvizcarra, Carlos A. SauraAbstract:EphA/ephrin signaling regulates Axon growth and guidance of neurons, but whether this process occurs also independently of ephrins is unclear. We show that presenilin-1 (PS1)/γ-secretase is required for Axon growth in the developing mouse brain. PS1/γ-secretase mediates Axon growth by inhibiting RhoA signaling and cleaving EphA3 independently of ligand to generate an intracellular domain (ICD) fragment that reverses Axon defects in PS1/γ-secretase- and EphA3-deficient hippocampal neurons. Proteomic analysis revealed that EphA3 ICD binds to non-muscle myosin IIA (NMIIA) and increases its phosphorylation (Ser1943), which promotes NMIIA filament disassembly and cytoskeleton rearrangement. PS1/γ-secretase-deficient neurons show decreased phosphorylated NMIIA and NMIIA/actin colocalization. Moreover, pharmacological NMII inhibition reverses Axon retraction in PS-deficient neurons suggesting that NMIIA mediates PS/EphA3-dependent Axon elongation. In conclusion, PS/γ-secretase-dependent EphA3 cleavage mediates Axon growth by regulating filament assembly through RhoA signaling and NMIIA, suggesting opposite roles of EphA3 on inhibiting (ligand-dependent) and promoting (receptor processing) Axon growth in developing neurons.