NOGO-A induction and localization during chick brain development indicate a role disparate from neurite outgrowth inhibition

Yu²,

J of Comparative Neurology

et al. 2017

Using Nogo antibodies with defined binding specificity, Nogo-B, but not Nogo-A, was localized on radial glia in the floor plate of mouse embryos. The presence of Nogo-B was confirmed in Nogo-A knockout mice. In explant cultures of embryonic day (E) 11 and E12 spinal cord, blocking of NgR function with antagonist peptide NEP1-40 reduced the crossing of newly arrived commissural axons, resulting in an accumulation of growth cones in the floor plate. Analysis of growth cone morphology demonstrated an increase in size of growth cones in the floor plate after peptide treatment, which was not detected in axons growing toward the midline. In knockout embryos, midline crossing was not affected by absence of Nogo-A. In co-culture experiments using collagen gel, floor plate showed a strong inhibitory effect on the extension of post-commissural neurites from the spinal cord. This effect was abolished by NEP1-40, and was observed neither in pre-commissural neurites, nor in post-commissural neurites grown with floor plate derived from Nogo-A knockout embryo. Furthermore, western blot analysis of conditioned medium from floor plates showed a truncated form of Nogo with molecular weight of 37 kDa, which could mediate the diffusible effect to axon growth. We conclude that Nogo-B is expressed in the floor plate of mouse embryo, which probably mediates axon crossing in the spinal cord by repelling axons out of the midline when they start upregulate NgR. Nogo acts on axon growth not only through a contact-mediated mechanism, but also through a diffusible mechanism.

Section: Introductionmentioning

confidence: 98%

Nogo‐B is the major form of Nogo at the floor plate and likely mediates crossing of commissural axons in the mouse spinal cord

Yu²,

J of Comparative Neurology

et al. 2017

Cell Biology International

“…As a potential solution to preventing the inhibitory effects of Nogo‐A, some studies have suggested neutralizing/blocking of endogenous Nogo‐A or its receptor Nogo receptor 1 (NgR1), or knockdown of the gene encoding Nogo‐A ( RTN4 ) (Schwab and Strittmatter, 2014). However, this can be quite difficult to achieve because other studies have shown Nogo‐A to potentially play an essential role in neuronal development/identification (Caltharp et al, 2007). Our results show the stability of neuronal morphology, cell alignment, and neurite elongation, as well as MN marker expression in the setting of EpoB at 10 nM differentiation group in the presence of Nogo‐A inhibitor.…”

Section: Discussionmentioning

confidence: 99%

Microtubule stabilizer epothilone B as a motor neuron differentiation agent for human endometrial stem cells

Mahmoodi

Ebrahimi‐Barough

et al. 2020

Microtubule-stabilizing agents (MSAs), until now, have primarily been considered for their anti-proliferative effects in the setting of cancer. However, recent studies have revealed that one particular MSA, epothilone B (EpoB), can promote axonal regeneration after traumatic spinal cord injuries (SCI) even in the presence of inhibitor molecules such as neurite outgrowth inhibitor-A (Nogo-A). On the basis of the importance of having an efficient motor neuron (MN) differentiation protocol for stem cell therapy and the attention of MSAs for SCI treatment, our study investigated the effect of EpoB on human endometrial stem cells (hEnSCs) differentiation into MN-like cells. hEnSCs were isolated and characterized by flow cytometry. The hEnSC cell viability was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. To mimic the in vivo inhibitory environment, hEnSCs were also differentiated in the presence of Nogo-A. After 15 days of differentiation, the expressions of MN-markers were evaluated by real-time reverse-transcriptase polymerase chain reaction and immunofluorescence. According to the MTT assay results, three doses (1, 5, and 10 nM) of EpoB were selected to evaluate their effect on MN-differentiation. All selected doses can increase the efficacy of hEnSCs differentiation into MN-like cells. In particular, the 10 nM EpoB dosage was shown to increase the axon elongation, cell alignment, and upregulation of these MN-markers compared with other doses. EpoB can improve MN differentiation from hEnSC and potentially provide a unique route for neuronal replacement in the setting of SCI.

“…It is known that NOGO‐A is a marker of adult oligodendrocytes and their myelinating elongations, and that this large protein in mammals inhibits axonal sprouting allowing the stabilization of nervous pathways in the SC and brain of mammals (Pernet & Schwab, 2012; Schwab, 2010). However, this does not seem to be the role of NOGO‐A during development, when this protein is instead expressed in neurogenic (stem) cells, migrating neuroblasts, and in developing axons (Baldwin & Giger, 2015; Caltharp et al, 2007; Huber et al, 2002). NOGO‐A tends to limit sprouting and address axon growth into fascicles, thus stabilizing the latter into fixed nervous pathways.…”

Section: Discussionmentioning

confidence: 99%

NOGO‐A immunolabeling is present in glial cells and some neurons of the recovering lumbar spinal cord in lizards

Alibardi

2020

Journal of Morphology

The transected lumbar spinal cord of lizards was studied for its ability to recover after paralysis. At 34 days post‐lesion about 50% of lizards were capable of walking with a limited coordination, likely due to the regeneration of few connecting axons crossing the transection site of the spinal cord. This region, indicated as “bridge”, contains glial cells among which oligodendrocytes and their elongation that are immunolabeled for NOGO‐A. A main reactive protein band occurs at 100–110 kDa but a weaker band is also observed around 240 kDa, suggesting fragmentation of the native protein due to extraction or to physiological processing of the original protein. Most of the cytoplasmic immunolabeling observed in oligodendrocytes is associated with vesicles of the endoplasmic reticulum. Also, the nucleus is labeled in some oligodendrocytes that are myelinating sparse axons observed within the bridge at 22–34 days post‐transection. This suggests that axonal regeneration is present within the bridge region. Immunolabeling for NOGO‐A shows that the protein is also present in numerous reactive neurons, in particular motor‐neurons localized in the proximal stump of the transected spinal cord. Ultrastructural immunolocalization suggests that NOGO is synthesized in the ribosomes of these neurons and becomes associated with the cisternae of the endoplasmic reticulum, probably following a secretory pathway addressed toward the axon. The present observations suggest that, like for the regenerating spinal cord of fish and amphibians, also in lizard NOGO‐A is present in reactive neurons and appears associated to axonal regeneration and myelination.