Project description:Nociceptors are neurons responsible for the detection of pain producing stimuli. Persistent changes in their activity, termed plasticity, benefit survival through injury avoidance and are regulated on a translational basis. Yet, the mRNAs whose translation facilitates plasticity are unknown. Here, we apply ribosome profiling to dorsal root ganglion and identify a small number of transcripts that are selectively translated in response to plasticity mediators. Among them are Arc and Fos, genes implicated in episodic learning in the brain. We demonstrate that the ribosomal S6 kinase 1 is responsible for their production in nociceptors. Blocking S6 driven translation also reduces pain associated behavioral responses in vivo. In addition to translation of coding regions of mRNA, we detect pervasive ribosome occupancy in 5’ untranslated regions. We find that peptides encoded by open reading frames in the 5’ untranslated regions of Calca and Egr2 increase neuronal excitability in vitro and are sufficient to induce pain-like behaviors in vivo. Together, our findings uncover new targets of translational control that drive changes in plasticity and suggest new mechanisms for targeted pain therapeutics that disrupt pain signaling.
Project description:Many eukaryotic RNAs have been considered non-coding as they only contain short open reading frames (sORFs). There is increasing evidence for the translation of these sORFs into bioactive peptides. Yet only a few small peptides are annotated in the model organism Arabidopsis thaliana. To aid the functional annotation of small peptides, we have developed ARA-PEPs, a repository and webserver of putative peptides encoded by sORFs in the Arabidopsis genome from in house Tiling arrays, RNA sequencing and from publicly available datasets. In order to identify novel oxidative stress-induced peptides in Arabidopsis thaliana a tiling array analysis (GeneChip® Arabidopsis Tiling 1.0R Arrays ) was performed on mRNA extracted from leaves inoculated with Botrytis cinerea (BC). Normalized log signals were obtained using the Affymetrix Tiling Analysis Software - Version 1.1, Build 2. ON and OFF probes were selected using a threshold, based on positive controls. Next, groups of 4-13 successive ON probes were combined into short TARs and a selection was made of TARs having an average signal intensity at least 2.6-fold higher after BC treatment compared to the control treatment, resulting in 195 BC induced TARs.
Project description:Sensitization of spinal nociceptive circuits plays a cardinal role in neuropathic pain. This sensitization depends on new gene expression that is primarily regulated via transcriptional and translational control mechanisms. The relative roles of these mechanisms in regulating gene expression in the clinically relevant chronic phase of neuropathic pain are not well understood. Here, we show that changes in gene expression in the spinal cord during the chronic phase of neuropathic pain are substantially regulated at the translational level. Downregulating spinal translation at the chronic phase alleviated pain hypersensitivity. Cell-type-specific profiling revealed that spinal inhibitory neurons exhibited greater changes in translation after peripheral nerve injury compared to excitatory neurons. Notably, increasing translation selectively in all inhibitory neurons or parvalbumin-positive (PV + ) interneurons, but not excitatory neurons, promoted mechanical pain hypersensitivity. Furthermore, increasing translation in PV + neurons decreased their intrinsic excitability and spiking activity, whereas reducing translation in spinal PV + neurons prevented the nerve injury-induced decrease in excitability. Thus, translational control mechanisms in the spinal cord, primarily in inhibitory neurons, play a critical role in mediating neuropathic pain hypersensitivity.
Project description:Neuropathic pain is a refractory condition that involves de novo protein synthesis in the nociceptive pathway. The mechanistic target of rapamycin (mTOR) is a master regulator of protein synthesis; however, mechanisms underlying its role in neuropathic pain remain elusive. Using spared nerve injury-induced neuropathic pain model, we found mTOR activation in large-diameter dorsal root ganglion (DRG) neurons and spinal microglia. However, selective ablation of mTOR in DRG neurons, rather than microglia, alleviated neuropathic pain. Combining transcriptomic profiling, electrophysiological recording and pharmacologic manipulations, we demonstrated that activated mTOR promoted neuropeptide Y (NPY) induction in mechanoreceptors and that NPY acted on Y2 receptors (Y2R) but not Y1R to enhance nociceptor excitability. Peripheral replenishment of NPY reversed pain alleviation upon mTOR removal, whereas Y2R antagonists prevented its function. Our findings reveal an unexpected link between mTOR and NPY in promoting nociceptor sensitization and neuropathic pain, through NPY/Y2R signaling-mediated intra-ganglionic transmission.
Project description:Nociceptive neurons respond to inflammation, initiating protective reflexes and alerting the host. Here we found that TRPV1 nociceptors express and activate the cytosolic DNA-sensing protein Stimulator of Interferon Genes (STING) in response to inflammation. Neuronal activation of STING promotes signaling through TBK1 and triggers a Type I interferon (IFN-I) response. The absence of STING led to heightened pain responses to chemical irritants or heat. In contrast, mice expressing a nociceptor-specific gain-of-function mutation in STING exhibited an IFN gene signature that reduced nociceptor excitability and inflammatory hyperalgesia. Importantly, several IFN-regulated genes (IRGs) were specific to nociceptor ion channels responsible for controlling neuronal activity and pain threshold. Therefore, STING promotes a pain-resolving IFN-I signaling pathway in nociceptors, thereby preventing sensitization and persistent pain
Project description:Background: Mirror-image pain (MIP), which develops from the healthy body region contralateral to the actual injured site, is a mysterious pain phenomenon accompanying many chronic pain conditions, including complex regional pain syndrome (CRPS). However, the pathogenesis of MIP still remained largely unknown. The purpose of this study is to perform an expression profiling to identify genes related with MIP in an animal model of CRPS-I. Methods: We established a rat chronic post-ischemic pain (CPIP) model to mimic human CRPS-I. RNA-sequencing (RNA-Seq), bioinformatics, qPCR, immunostaining and animal behavioral assays were used to screen potential genes in contralateral dorsal root ganglia (DRG) that may be involved in MIP. Results: The CPIP model rats developed robust and persistent MIP in contralateral hind paws. Bilateral DRG neurons did not exhibit obvious neuronal damage. RNA-Seq of contralateral DRG from CPIP model rats identified a total 527 differentially expressed genes (DEGs) vs. control rats. The expression changes of several representative DEGs were verified by qPCR. Bioinformatics analysis indicated that immune system process, innate immune response and cell adhesion were among the mostly enriched biological processes, which are all important processes involved in pain sensitization, neuroinflammation and chronic pain. We further identified DEGs potentially involved in pain mechanisms or enriched in small- to medium-sized sensory neurons or TRPV1-lineage nociceptors. By comparing with published datasets summarizing genes enriched in pain mechanisms, we sorted out a core set of genes which might contribute to nociception and pain mechanism in MIP. Conclusions: We provided by far the first study to profile gene expression changes and pathway analysis of contralateral DRG for investigating MIP mechanisms. This work may provide novel insights into understanding the mysterious mechanisms underlying MIP.
Project description:Studies have revealed dozens of functional peptides in putative ‘noncoding’ regions and raised the question of how many proteins are encoded by noncanonical open reading frames (ORFs). We comprehensively annotated genome-wide translated ORFs across five eukaryotic by analyzing ribosome profiling reads. We revealed pervasive translation in annotated untranslated regions of mRNAs or off-frame regions (i.e., uORFs, dORFs, and iORFs). We developed a logistic regression model based on ORF features to calculate the peptide functional probability in humans. Systematic ectopic expression experiments showed that peptides encoded by ncORFs follow the basic principles governing conventional protein subcellular localization and carry out diverse biological functions.
Project description:Background: The pathogenesis of neuropathic pain and the reasons for the prolonged unhealing are still unknown. Increasing evidence suggests that oestrogen sex differences play a role in pain sensitivity, but few studies focused on the role of oestrogen receptor which maybe an important molecular component contributing to peripheral pain transduction. We aimed to investigate the impact of ooestrogen receptors in nociceptive neuronal response in the dorsal root ganglion (DRG) and spinal dorsal horn using a spared nerve injury (SNI) rat model of chronic pain. Methods: We used a class of oestrogen receptors antagonists and agonists intrathecal (i.t.) administrated to male rats with SNI or normal rats to identify the main receptor. Moreover, we applied genes identified through genomic metabolic analysis to determine the key metabolism point and elucidate potential mechanisms mediating continuous neuronal sensitisation and neuroinflammation responses in neuropathic pain. The excitability of DRG neurons was detected using the patch clamp technique. Primary culture was used to extract microglia and DRG neurons, and siRNA transfection was used to silence receptor protein expression. Immunofluorescence, Western blotting, qPCR and behavioral testing were used to assess the expressions, cellular distributions, and actions of main receptor and its related signaling molecules. Results: Increasing the expression and function of G protein-coupled oestrogen receptor (GPER), but not oestrogen receptor-α (ERα) and oestrogen receptor-β (ERβ), in the DRG neuron and microglia, but not the dorsal spinal cord, contributed to SNI-induced neuronal sensitisation. Inhibiting GPER expression in the DRG alleviated SNI-induced pain behaviours and neuroinflammation by downregulating iNOS, IL-1β and IL-6 expression as well as restoring GABAα2 expression simultaneously. Additionally, the positive interaction between GPER and β-alanine, β-alanine accumulation enhances pain sensation and promotes chronic pain development. Conclusion: GPER activation in the DRG causes a positive interaction of β-alanine with iNOS, IL-1β and IL-6 expression and represses GABAα2 involved in post-SNI neuropathic pain development. Blocking GPER and eliminating β-alanine in the DRG neuron and microglia may prevent neuropathic pain development.