scholarly journals Deletion of SIRPα (signal regulatory protein-α) promotes phagocytic clearance of myelin debris in Wallerian degeneration, axon regeneration, and recovery from nerve injury

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Gerard Elberg ◽  
Sigal Liraz-Zaltsman ◽  
Fanny Reichert ◽  
Takashi Matozaki ◽  
Michael Tal ◽  
...  
Keyword(s):  
Nerve Injury ◽  
Wallerian Degeneration ◽  
Axon Regeneration ◽  
Recovery Of Function ◽  
Regulatory Protein ◽  
Wild Type ◽  
Myelin Debris ◽  
Dependent Inhibition ◽  
Severed Axons

Abstract Background Recovery of function from traumatic nerve injury depends on the ability of severed axons to grow/regenerate back to their target tissues. This is achieved by successfully crossing the lesion site where physical impact severed axons, determined by the type of trauma, followed by successfully growing throughout the Wallerian degenerating nerve segment located distal to and beyond the lesion site, determined by the nature of Wallerian degeneration. The protracted removal of myelin debris in Wallerian degeneration, which leads residual myelin debris to slow down axon growth, impedes recovery of function. We focused in this study on mechanism(s) that delay the removal of myelin debris in Wallerian degeneration and so impede recovery. Previously, we showed that myelin debris inhibited its own phagocytosis in primary cultured macrophages and microglia as CD47 on myelin ligated SIRPα (signal regulatory protein-α) on phagocytes, and sequentially, SIRPα generated “don’t eat me” signaling. We also demonstrated that serum inhibited phagocytosis in a SIRPα-dependent manner. Herein, we aimed to determine whether SIRPα-dependent inhibition of phagocytosis in macrophages impedes the in vivo removal of myelin debris in Wallerian degeneration, further leading to impaired healing. Methods Using SIRPα null (SIRPα−/−) and littermate wild-type (SIRPα+/+) mice, we studied the recovery of sensory and motor functions from nerve injury and, further, axon regeneration, SIRPα expression, myelin debris removal, and the phagocytic capacity and presence of macrophages in Wallerian degeneration. Results Myelin debris removal, axon regeneration, and the recovery of functions were all faster in SIRPα−/− mice than in wild-type mice. Between the two cell types that mostly scavenge myelin debris, macrophages but not Schwann cells expressed SIRPα in wild-type mice, and furthermore, SIRPα−/− macrophages phagocytosed significantly more than wild-type macrophages. Conclusions Our findings suggest an intrinsic normally occurring SIRPα-dependent mechanism that impedes the in vivo removal of myelin debris in Wallerian degeneration by inhibiting the phagocytosis of myelin debris in macrophages, hence preventing fast growing axons from fully implementing their regenerative potential. Thus, accelerating the removal of myelin debris by eliminating SIRPα-dependent inhibition of phagocytosis will most likely advance recovery of functions from nerve injury.

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 Interaction between transcriptional activator protein LAC9 and negative regulatory protein GAL80.

1989 ◽  
Vol 9 (7) ◽  
pp. 2950-2956 ◽  
Author(s):  
J M Salmeron ◽  
S D Langdon ◽  
S A Johnston
Keyword(s):  
Transcriptional Activation ◽  
Kluyveromyces Lactis ◽  
Regulatory Protein ◽  
Wild Type ◽  
Galactose Metabolism ◽  
Metabolism Regulation ◽  
Transcriptional Activator Protein ◽  
The Difference ◽  
Carboxy Terminal

In Saccharomyces cerevisiae, transcriptional activation mediated by the GAL4 regulatory protein is repressed in the absence of galactose by the binding of the GAL80 protein, an interaction that requires the carboxy-terminal 28 amino acids of GAL4. The homolog of GAL4 from Kluyveromyces lactis, LAC9, activates transcription in S. cerevisiae and is highly similar to GAL4 in its carboxyl terminus but is not repressed by wild-type levels of GAL80 protein. Here we show that GAL80 does repress LAC9-activated transcription in S. cerevisiae if overproduced. We sought to determine the molecular basis for the difference in the responses of the LAC9 and GAL4 proteins to GAL80. Our results indicate that this difference is due primarily to the fact that under wild-type conditions, the level of LAC9 protein in S. cerevisiae is much higher than that of GAL4, which suggests that LAC9 escapes GAL80-mediated repression by titration of GAL80 protein in vivo. The difference in response to GAL80 is not due to amino acid sequence differences between the LAC9 and GAL4 carboxyl termini. We discuss the implications of these results for the mechanism of galactose metabolism regulation in S. cerevisiae and K. lactis.

scholarly journals RICK Promotes Inflammation and Lethality after Gram-Negative Bacterial Infection in Mice Stimulated with Lipopolysaccharide

2009 ◽  
Vol 77 (4) ◽  
pp. 1569-1578 ◽  
Author(s):  
Jong-Hwan Park ◽  
Yun-Gi Kim ◽  
Gabriel Núñez
Keyword(s):  
Protein Kinase ◽  
Regulatory Protein ◽  
Mitogen Activated Protein Kinase ◽  
Gram Negative Bacteria ◽  
Wild Type ◽  
Proinflammatory Response ◽  
Interacting Protein ◽  
Gram Negative ◽  
Mitogen Activated Protein

ABSTRACT RICK (receptor-interacting protein-like interacting caspase-like apoptosis regulatory protein kinase), a serine-threonine kinase, functions downstream of the pattern recognition receptors Nod1 and Nod2 to mediate NF-κB and mitogen-activated protein kinase (MAPK) activation in response to specific microbial stimuli. However, the function of RICK in the recognition and host defense of gram-negative bacteria remains poorly understood. We report here that infection of wild-type and RICK-deficient macrophages with Pseudomonas aeruginosa and Escherichia coli elicited comparable activation of NF-κB and MAPKs as well as secretion of proinflammatory cytokines. However, production of interleukin 6 (IL-6) and IL-1β induced by these gram-negative bacteria was impaired in RICK-deficient macrophages when the cells had previously been stimulated with lipopolysaccharide (LPS) or E. coli. The diminished proinflammatory response of RICK-deficient macrophages to bacteria was associated with reduced activation of NF-κB and MAPKs. Importantly, mutant mice deficient in RICK were less susceptible than wild-type mice to P. aeruginosa infection when the animals had previously been stimulated with LPS. The reduced lethality of RICK-deficient mice infected with P. aeruginosa was independent of pathogen clearance but was associated with diminished production of proinflammatory molecules in vivo. These results demonstrate that RICK contributes to the induction of proinflammatory responses and susceptibility to gram-negative bacteria after exposure to LPS, a condition that is associated with reduced Toll-like receptor signaling.

scholarly journals Intracellular phospholipase A2 group IVA and group VIA play important roles in Wallerian degeneration and axon regeneration after peripheral nerve injury

Brain ◽  
2008 ◽  
Vol 131 (10) ◽  
pp. 2620-2631 ◽  
Author(s):  
Rubèn López-Vales ◽  
Xavier Navarro ◽  
Takao Shimizu ◽  
Constantinos Baskakis ◽  
George Kokotos ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Phospholipase A2 ◽  
Nerve Injury ◽  
Peripheral Nerve Injury ◽  
Wallerian Degeneration ◽  
Axon Regeneration ◽  
Group Iva

scholarly journals Promoting axon regeneration by enhancing the non-coding function of the injury-responsive coding gene Gpr151

2021 ◽  
Author(s):  
Bohm Lee ◽  
Jinyoung Lee ◽  
Yewon Jeon ◽  
Hyemin Kim ◽  
Minjae Kwon ◽  
...  
Keyword(s):  
Nerve Injury ◽  
Rna Binding ◽  
Axon Regeneration ◽  
Rna Binding Proteins ◽  
Nerve Repair ◽  
Coding Regions ◽  
Protein Functions ◽  
Injury Models

AbstractGene expression profiling in response to nerve injury has been mainly focused on protein functions of coding genes to understand mechanisms of axon regeneration and to identify targets of potential therapeutics for nerve repair. However, the protein functions of several highly injury-induced genes including Gpr151 for regulating the regenerative ability remain unclear. Here we present an alternative approach focused on non-coding functions of the coding genes, which led to the identification of the non-coding function of Gpr151 RNA interacting with RNA-binding proteins such as CSDE1. Gpr151 promotes axon regeneration by the function of its 5’-untranslated region (5’UTR) and expression of an engineered form of the 5’UTR improves regenerative capacity in vitro and in vivo in both sciatic nerve and optic nerve injury models. Our data suggest that searching injury-induced coding genes potentially functioning by their non-coding regions is required for the RNA-based gene therapy for improving axon regeneration.

scholarly journals Collapsin Response Mediator Protein 4 (CRMP4) Facilitates Wallerian Degeneration and Axon Regeneration following Sciatic Nerve Injury

eNeuro ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. ENEURO.0479-19.2020
Author(s):  
Marie-Pier Girouard ◽  
Tristan Simas ◽  
Luyang Hua ◽  
Barbara Morquette ◽  
Mohamad R. Khazaei ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Nerve Injury ◽  
Wallerian Degeneration ◽  
Axon Regeneration ◽  
Sciatic Nerve Injury ◽  
Collapsin Response Mediator Protein ◽  
Mediator Protein

scholarly journals Changes in Liver Gene Expression of Azin1 Knock-out Mice

2010 ◽  
Vol 65 (7-8) ◽  
pp. 519-527 ◽  
Author(s):  
Tao Wan ◽  
Yuan Hu ◽  
Ailong Huang ◽  
Ken-ichi Yamamura ◽  
Hua Tang
Keyword(s):  
Ornithine Decarboxylase ◽  
Regulatory Protein ◽  
Fold Change ◽  
Oligonucleotide Array ◽  
Wild Type ◽  
Polyamine Biosynthesis ◽  
Knock Out ◽  
Knock Out Mice

The ornithine decarboxylase antizyme inhibitor (AZI) was discovered as a protein that binds to the regulatory protein antizyme and inhibits the ability of antizyme to interact with the enzyme ornithine decarboxylase (ODC). Several studies showed that the AZI protein is important for cell growth in vitro. However, the function of this gene in vivo remained unclear. In our study, we analyzed the transcriptional profiles of livers on the 19th day of pregnancy of Azin1 knock-out mice and wild-type mice using the Agilent oligonucleotide array. Compared to the wild-type mice, in the liver of Azin1 knock-out mice 1812 upregulated genes (fold change ≥ 2) and 1466 downregulated genes (fold change ≤ 0.5) were showed in the microarray data. Altered genes were then assigned to functional categories and mapped to signaling pathways. These genes have functions such as regulation of the metabolism, transcription and translation, polyamine biosynthesis, embryonic morphogenesis, regulation of cell cycle and proliferation signal transduction cascades, immune response and apoptosis. Real-time PCR was used to confirm the differential expression of some selected genes. Overall, our study provides novel understanding of the biological functions of AZI in vivo.

scholarly journals DNA Bending by AraC: a Negative Mutant

1998 ◽  
Vol 180 (16) ◽  
pp. 4227-4232 ◽  
Author(s):  
Beatrice Saviola ◽  
Robert R. Seabold ◽  
Robert F. Schleif
Keyword(s):  
Dna Binding ◽  
Leucine Zipper ◽  
Dna Bending ◽  
Regulatory Protein ◽  
Transcription Activation ◽  
Binding Domain ◽  
Dominant Negative ◽  
Dna Binding Domain ◽  
Wild Type

ABSTRACT We sought a mutation in the DNA binding domain of the arabinose operon regulatory protein, AraC, of Escherichia coli that allows the protein to bind DNA normally but not activate transcription. The mutation was isolated by mutagenizing a plasmid overproducing a chimeric leucine zipper-AraC DNA binding domain and screening for proteins that were trans dominant negative with regard to wild-type AraC protein. The mutant with the lowest transcription activation of the araBAD promoter was studied further. It proved to alter a residue that had previously been demonstrated to contact DNA. Because the overproduced mutant protein still bound DNA in vivo, it is deficient in transcription activation for some reason other than absence of DNA binding. Using the phase-sensitive DNA bending assay, we found that wild-type AraC bends DNA about 90° whereas the mutant bends DNA by a smaller amount.

Interaction between transcriptional activator protein LAC9 and negative regulatory protein GAL80

1989 ◽  
Vol 9 (7) ◽  
pp. 2950-2956
Author(s):  
J M Salmeron ◽  
S D Langdon ◽  
S A Johnston
Keyword(s):  
Transcriptional Activation ◽  
Kluyveromyces Lactis ◽  
Regulatory Protein ◽  
Wild Type ◽  
Galactose Metabolism ◽  
Metabolism Regulation ◽  
Transcriptional Activator Protein ◽  
The Difference ◽  
Carboxy Terminal

In Saccharomyces cerevisiae, transcriptional activation mediated by the GAL4 regulatory protein is repressed in the absence of galactose by the binding of the GAL80 protein, an interaction that requires the carboxy-terminal 28 amino acids of GAL4. The homolog of GAL4 from Kluyveromyces lactis, LAC9, activates transcription in S. cerevisiae and is highly similar to GAL4 in its carboxyl terminus but is not repressed by wild-type levels of GAL80 protein. Here we show that GAL80 does repress LAC9-activated transcription in S. cerevisiae if overproduced. We sought to determine the molecular basis for the difference in the responses of the LAC9 and GAL4 proteins to GAL80. Our results indicate that this difference is due primarily to the fact that under wild-type conditions, the level of LAC9 protein in S. cerevisiae is much higher than that of GAL4, which suggests that LAC9 escapes GAL80-mediated repression by titration of GAL80 protein in vivo. The difference in response to GAL80 is not due to amino acid sequence differences between the LAC9 and GAL4 carboxyl termini. We discuss the implications of these results for the mechanism of galactose metabolism regulation in S. cerevisiae and K. lactis.

scholarly journals Screening for axon regeneration promoting compounds with human iPSC-derived motor neurons

2021 ◽  
Author(s):  
Tammy Szu-Yu Ho ◽  
J. Tabitha Hees ◽  
Zhuqiu Xu ◽  
Riki Kawaguchi ◽  
Natalia P Biscola ◽  
...  
Keyword(s):  
Nerve Injury ◽  
Motor Neurons ◽  
Large Scale ◽  
Axon Regeneration ◽  
Induced Pluripotent Stem Cell ◽  
Screening Strategy ◽  
Therapeutic Interventions ◽  
Induced Pluripotent ◽  
Human Ipsc

CNS neurons do not regenerate after injury, leading to permanent functional deficits. Although sensory and motor neuron axons do regrow after peripheral nerve injury, functional outcome is limited due to the incomplete and slow regrowth. The lack of human-relevant assays suitable for large-scale drug screens has limited neuro-repair therapy discovery. To address this we developed a phenotypic screening strategy using human induced pluripotent stem cell-derived motor neurons to identify axon-regeneration promoting compounds and targets. The screens involve both re-plating human motor neurons on chondroitin sulfate proteoglycans and measuring regeneration responses to laser axotomy in spot cultures, and from them we identified multiple hits that promote injured axon regrowth. The top hit blebbistatin, a non-muscle myosin II inhibitor, accelerated axon regeneration and functional recovery after sciatic nerve injury in vivo. Human injury in a dish assays are suitable, therefore, to screen for therapeutic interventions that can induce or accelerate axon regeneration.

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