Gene expression change in the lingual nerve and the traumatic neuromas after the injured lingual nerve.
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ABSTRACT: The lingual nerves are incidentally injured in many oral and maxillofacial surgical procedures, traumatic neuroma was observed at the proximal stump of the injured lingual nerve in patients with severe lingual nerve disturbance. Various genes including genes related to nerve regeneration are expressed in the rat and mouse traumatic neuroma, as regeneration mechanism works after lingual nerve injury. Few reported have showed the expressed genes in the traumatic neuroma of the human lingual nerve. In this study, we compared the gene expression between pooled RNA sample from three traumatic neuromas removed in microneurosurgery in the lingual nerve and an RNA sample from the normal lingual nerve on the unaffected side of the removed tongue with cancer. The 2,357 genes increased more than twofold in the traumatic neuroma compared with the normal lingual nerve. Then, we analyzed the upregulated genes in DAVID and DAVID indicated that the 20 upregulated genes were associated with protein secretion to the extracellular space in the pathways. This study identified the 20 candidate genes at the nerve regeneration stage in the traumatic neuroma in the human lingual nerve.
Project description:Peripheral nerve repair and functional recovery depend on the rate of nerve regeneration and the quality of target reinnervation. It is important to fully understand the cellular and molecular basis underlying the specificity of peripheral nerve regeneration, which means the achieving of respective correct pathfinding and accurate target reinnervation for regrowing motor and sensory axons. In this study, a quantitative proteomic technique, based on isobaric tags for relative and absolute quantitation (iTRAQ) was used to profile the protein expression pattern between single motor and sensory nerves at 14 days after peripheral nerve transection. Among a total of 1259 proteins identified, 176 proteins showed the differential expressions between injured motor and sensory nerves. Quantitative real-time RT-PCR and Western blot analysis were applied to validate the proteomic data on representative differentially expressed proteins. Functional categorization indicated that differentially expressed proteins were linked to a diverse array of molecular functions, including axonogenesis, response to axon injury, tissue remodeling, axon ensheathment, cell proliferation and adhesion, vesicle-mediated transport, response to oxidative stress, internal signal cascade, and macromolecular complex assembly, which might play an essential role in peripheral motor and sensory nerve regeneration. Overall, we hope that the proteomic database obtained in this study could serve as a solid foundation for the comprehensive investigation of differentially expressed proteins between injured motor and sensory nerves and for the mechanism elucidation of the specificity of peripheral nerve regeneration.
Project description:ChIP-seq of H3K4me3 in rat peripheral nerve was used to identify transcription start sites associated with Schwann cell-expressed genes. The analysis was performed in injured and control nerve to identify injury-responsive changes in Schwann cells. H3K4me3 ChIP samples were prepared from rat sciatic nerve at 1 day post-transection using both the distal stump of the injured nerve and the contralateral (sham) nerve.
Project description:To gain a better understanding of the factors necessary for successful CNS regeneration, a temporal analysis of the changes in gene expression in the eye caused by optic nerve injury was conducted. Dual color oligonucleotide microarrays were used to compare total RNA harvested from the eyes of sham-operated and optic nerve-injured fish at 3, 24, and 168 hours following surgery. Optic nerve injured fish are compared to sham-operated fish in order to eliminate gene expression due to non-neuronal damage and inflammatory response. Statistical analyses identified 131 genes with a 2.0-fold or greater difference in expression. Wild type zebrafish were obtained from a local pet store. Optic nerve injury was conducted using a severing model accomplished as follows. Zebrafish were anesthetized in 0.2% MS-222 dissolved in tank water. The muscles surrounding the eye were cut and the eye angled rostrally to expose the nerve. The optic nerve was then severed using microsissors without damaging the ophthalmic artery. In sham operated fish the muscles surrounding the eye were severed but the nerve was not damaged. RNA was extracted from the eye at three time points following surgery 3 hours, 24 hours, and 168 hours. RNA was pooled from multiple fish to achieve 10 ug total RNA. Samples were collected in triplicate per time point. Gene expression was analyzed on a dual color oligonucleotide array where the optic nerve injured fish were compared to sham-operated fish. Four samples of RNA were also collected from control fish and compared to each other on the microarray to confirm that processing did not create expression differences.
Project description:To gain a better understanding of the factors necessary for successful CNS regeneration, a temporal analysis of the changes in gene expression in the eye caused by optic nerve injury was conducted. Dual color oligonucleotide microarrays were used to compare total RNA harvested from the eyes of sham-operated and optic nerve-injured fish at 3, 24, and 168 hours following surgery. Optic nerve injured fish are compared to sham-operated fish in order to eliminate gene expression due to non-neuronal damage and inflammatory response. Statistical analyses identified 131 genes with a 2.0-fold or greater difference in expression.
Project description:Sciatic nerve crush (SNC) triggers sterile inflammation within the distal nerve and de-afferented dorsal root ganglia (DRGs). In the nerve, neutrophils and pro-inflammatory Ly6Chigh monocytes appear first and rapidly give way to Ly6Clow resolving macrophages. Transcriptional profiling of injured nerve tissue identifies six macrophage subpopulations, repair Schwann cells and mesenchymal cells as the main cell types. Macrophages at the nerve crush site are distinct from macrophages associated with degenerating nerve fibers. Monocytes and macrophages in the injured nerve “eat” apoptotic cell corpses of leukocytes and thereby contribute to an anti-inflammatory milieu. Studies with chimeric mice show that following SNC few blood-derived immune cells enter DRGs. Myeloid cells in the injured nerve, but not DRGs, express the receptor for the chemokine GM-CSF. In the absence of GM-CSF, conditioning-lesion induced regeneration of DRG neuron central projections is abrogated. Thus, a carefully orchestrated immune response in the nerve is required for conditioning-lesion induced neurorepair.
Project description:Peripheral glial Schwann cells switch to a repair state after nerve injury, proliferate to supply lost cell population, migrate to form regeneration tracks, and generates a permissive microenvironment for nerve regeneration. Exploring essential regulators of the repair responses of Schwann cells may benefit the clinical treatment for peripheral nerve injury. In the present study, FOSL1 regulates Schwann cell phenotype modulation and provided a novel therapeutic approach to orchestrate the regeneration and functional recovery of injured peripheral nerves.
Project description:Severe peripheral nerve injury (PNI) often causes significant movement disorders and intractable pain. Therefore, promoting nerve regeneration while avoiding neuropathic pain, a problem that remains unsolved, is key to the clinical treatment of PNI patients. Here, we establish a novel spared nerve crush (SNC) rat model that successfully reproduces axonal regeneration and neuropathic pain after PNI. Subsequently, we obtained single-cell RNA sequencing (scRNA-seq) data from rat directly injured and indirectly injured rat dorsal root ganglion (DRG) neurons at various time points after SNC and found that the PEP1 neuronal subtype in directly injured DRG is of particular interest. Through experimental design, sc-RNA sequence processing (EDSSP) and functional verification, we identified a potential key gene, Adcyap1, that encodes a key molecule linking nerve regeneration and pain after PNI. Our study sheds new light on the intrinsic link between axonal regeneration and neuropathic pain following PNI and provides new molecular targets and ideas for therapeutic intervention.
Project description:Sciatic nerve crush (SNC) triggers sterile inflammation within the distal nerve and deafferented dorsal root ganglia (DRGs). Granulocytes and pro-inflammatory Ly6Chigh monocytes infiltrate the nerve first, and rapidly give way to Ly6C- inflammation-resolving macrophages. Inflammation in DRGs is dominated by tissue resident macrophages, with little contribution from hematogenous leukocytes. Single-cell transcriptomics analysis of injured nerve identified six macrophage subpopulations, repair Schwann cells, and mesenchymal cells as the main cell types. Macrophages at the nerve crush site are distinct from macrophages associated with degenerating nerve fibers. Monocytes and macrophages in the injured nerve “eat” cell corpses of apoptotic leukocytes and thereby promote an anti-inflammatory milieu. Myeloid cells in the injured nerve, but not DRGs, strongly express the receptor for the chemokine GM-CSF. In the absence of GM-CSF, conditioning-lesion induced regeneration of DRG neuron central projections is abolished. Thus, a carefully orchestrated immune response in the nerve is required for conditioning-lesion induced neurorepair.
Project description:Fibro-adipogenic progenitors (FAPs) are muscle-resident mesenchymal progenitors that can contribute to muscle tissue homeostasis and regeneration, as well as postnatal maturation and lifelong maintenance of the neuromuscular system. Recently, traumatic injury to the peripheral nerve was shown to activate FAPs, suggesting that FAPs can respond to nerve injury. However, questions of how FAPs can sense the anatomically distant peripheral nerve injury and whether FAPs can directly contribute to nerve regeneration remained unanswered. Here, utilizing single-cell transcriptomics and mouse models, we discovered that a subset of FAPs expressing GDNF receptors Ret and Gfra1 can respond to peripheral nerve injury by sensing GDNF secreted by Schwann cells. Upon GDNF sensing, this subset becomes activated and expresses Bdnf. FAP-specific inactivation of Bdnf (Prrx1-Cre; Bdnf-fl/fl) resulted in delayed nerve regeneration owing to defective remyelination, indicating that GDNF-sensing FAPs play an important role in the remyelination process during peripheral nerve regeneration. In aged mice, significantly reduced Bdnf expression in FAPs was observed upon nerve injury, suggesting the clinical relevance of FAP-derived BDNF in the age-related delays in nerve regeneration. Collectively, our study revealed the previously unidentified role of FAPs in peripheral nerve regeneration, and the molecular mechanism behind FAPs’ response to peripheral nerve injury.