NFATc2-dependent epigenetic downregulation of the TSC2/Beclin-1 pathway is involved in neuropathic pain induced by oxaliplatin.

Neuropathic pain is a common dose-limiting side effect of oxaliplatin, which hampers the effective treatment of tumors. Here, we found that upregulation of transcription factor NFATc2 decreased the expression of Beclin-1, a critical molecule in autophagy, in the spinal dorsal horn, and contributed to neuropathic pain following oxaliplatin treatment. Meanwhile, manipulating autophagy levels by intrathecal injection of rapamycin (RAPA) or 3-methyladenine (3-MA) differentially altered mechanical allodynia in oxaliplatin-treated or naïve rats. Utilizing chromatin immunoprecipitation-sequencing (ChIP-seq) assay combined with bioinformatics analysis, we found that NFATc2 negatively regulated the transcription of tuberous sclerosis complex protein 2 (TSC2), which contributed to the oxaliplatin-induced Beclin-1 downregulation. Further assays revealed that NFATc2 regulated histone H4 acetylation and methylation in the TSC2 promoter site 1 in rats' dorsal horns with oxaliplatin treatment. These results suggested that NFATc2 mediated the epigenetic downregulation of the TSC2/Beclin-1 autophagy pathway and contributed to oxaliplatin-induced mechanical allodynia, which provided a new therapeutic insight for chemotherapy-induced neuropathic pain.

Metformin Relieves Bortezomib-Induced Neuropathic Pain by Regulating AMPKa2-Mediated Autophagy in the Spinal Dorsal Horn.

Chemotherapy-induced neuropathic pain is a major clinical problem with limited treatment options. Here, we show that metformin relieves bortezomib (BTZ)-evoked induction and maintenance of neuropathic pain by preventing the reduction in the expression of Beclin-1, an autophagy marker, in the spinal dorsal horn. Application of rapamycin or 3-methyladenine, autophagy inducer and inhibitor, respectively, affected the mechanical allodynia differently. Co-application of 3-methyladenine and metformin partially inhibited the effect of metformin in recovering Beclin-1 expression and in reducing the pain behavior in rats subjected to BTZ treatment. BTZ treatment also reduced the expression of AMPKa2 in the dorsal horn, which was recovered by metformin treatment. Overexpression of AMPKa2 attenuated the BTZ-evoked reduction in Beclin-1 expression and mechanical allodynia, whereas intrathecal injection of AMPKa2 siRNA decreased the Beclin-1 expression and induced mechanical allodynia in naive rats. Moreover, BTZ treatment increased the GATA3 expression in the dorsal horn, and GATA3 siRNA attenuated the AMPKa2 downregulation and mechanical allodynia induced by BTZ. Chromatin immunoprecipitation further showed that BTZ induced an increased recruitment of GATA3 to multiple sites in the AMPKa2 promoter region. Furthermore, decreased acetylation and increased methylation of histone H3 in the AMPKa2 promoter in the spinal dorsal horn was detected after BTZ treatment. Our findings suggest that metformin may regulate AMPKa2-mediated autophagy in the dorsal horn and alleviate the behavioral hypersensitivity induced by BTZ.

ZEB1 Induces Ddr1 Promoter Hypermethylation and Contributes to the Chronic Pain in Spinal Cord in Rats Following Oxaliplatin Treatment.

Application of chemotherapeutic oxaliplatin represses gene transcription through induction of DNA methylation, which may contribute to oxaliplatin-induced chronic pain. Here, Ddr1, which showed an increased methylation in the promoter, was screened from the SRA methylation database (PRJNA587622) after oxaliplatin treatment. qPCR and MeDIP assays verified that oxaliplatin treatment increased the methylation in Ddr1 promoter region and decreased the expression of DDR1 in the neurons of spinal dorsal horn. In addition, overexpression of DDR1 by intraspinal injection of AAV-hSyn-Ddr1 significantly alleviated the mechanical allodynia induced by oxaliplatin. Furthermore, we found that oxaliplatin treatment increased the expression of DNMT3b and ZEB1 in dorsal horn neurons, and promoted the interaction between DNMT3b and ZEB1. Intrathecal injection of ZEB1 siRNA inhibited the enhanced recruitment of DNMT3b and the hypermethylation in Ddr1 promoter induced by oxaliplatin. Finally, ZEB1 siRNA rescued the DDR1 downregulation and mechanical allodynia induced by oxaliplatin. In conclusion, these results suggested that the ZEB1 recruited DNMT3b to the Ddr1 promoter, which induced the DDR1 downregulation and contributed to the oxaliplatin-induced chronic pain.

Oxaliplatin-induced neuropathic pain involves HOXA6 via a TET1-dependent demethylation of the SOX10 promoter.

Chemotherapy-induced neuropathic pain is a common dose-limiting side effect of cancer treatment but the underlying mechanisms are largely unknown. Here, we used a whole-genome expression microarray and gene ontology analysis to identify the upregulation of a sequence-specific DNA-binding protein, HOXA6, in the spinal dorsal horn on Day 10 after injection of rats with oxaliplatin. Genetic disruption of HOXA6 with siRNAs alleviated mechanical allodynia after oxaliplatin administration. Reduced representation bisulfite sequencing assays indicated that oxaliplatin decreased the methylation levels of the SOX10 promoter but not of HOXA6. TET1 was also upregulated by oxaliplatin. Genetic disruption of TET1 with siRNA blocked the promoter demethylation of SOX10 and the upregulation of HOXA6 and SOX10. Importantly, inhibition of SOX10 by intrathecal application of SOX10 siRNA ameliorated the mechanical allodynia induced by oxaliplatin and downregulated the expression of HOXA6. Consistently, overexpression of SOX10 through intraspinal injection of AAV-SOX10-EGFP produced mechanical allodynia and upregulated the expression of spinal dorsal horn HOXA6. Moreover, chromatin immunoprecipitation assays demonstrated that oxaliplatin increased the binding of SOX10 to the promoter region of HOXA6. Taken together, our data suggest that HOXA6 upregulation through the TET1-mediated promoter demethylation of SOX10 may contribute to oxaliplatin-induced neuropathic pain.

NEFA can serve as good biological markers for the diagnosis of depression in adolescents.

BACKGROUND: The incidence of adolescent depression has markedly risen in recent years, with a high recurrence rate into adulthood. Diagnosis in adolescents is challenging due to subjective factors, highlighting the crucial need for objective diagnostic markers. METHODS: Our study enrolled 204 participants, including healthy controls (n = 88) and first-episode adolescent depression patients (n = 116). Serum samples underwent gas chromatography-mass spectrometry (GC-MS) analysis to assess non-esterified fatty acids (NEFA) expression. Machine learning and ROC analysis were employed to identify potential biomarkers, followed by bioinformatics analysis to explore underlying mechanisms. RESULTS: Nearly all differentially expressed NEFA exhibited significant downregulation. Notably, nonanoic acid, cis-10-pentadecenoic acid, cis-10-carboenoic acid, and cis-11-eicosenoic acid demonstrated excellent performance in distinguishing adolescent depression patients. Metabolite-gene interaction analysis revealed these NEFAs interacted with multiple genes. KEGG pathway analysis on these genes suggested that differentially expressed NEFA may impact PPAR and cAMP signaling pathways. LIMITATIONS: Inclusion of diverse populations for evaluation is warranted. Biomarkers identified in this study require samples that are more in line with the experimental design for external validation, and further basic research is necessary to validate the potential depressive mechanisms of NEFA. CONCLUSIONS: The overall reduction in NEFA expression in first-episode adolescent depression patients suggests a potential mediation of depression symptoms through cAMP and PPAR signaling pathways. NEFA levels show promise as a diagnostic tool for identifying first-episode adolescent depression patients.

Mapping metabolite change in the mouse brain after esketamine injection by ambient mass spectrometry imaging and metabolomics.

Ketamine is a new, fast, and effective antidepression treatment method; however, the possible dissociation effects, sensory changes, abuse risk, and the inability to accurately identify whether patients have a significant response to ketamine limit its clinical use. Further exploration of the antidepressant mechanisms of ketamine will contribute to its safe and practical application. Metabolites, the products of upstream gene expression and protein regulatory networks, play an essential role in various physiological and pathophysiological processes. In traditional metabonomics it is difficult to achieve the spatial localization of metabolites, which limits the further analysis of brain metabonomics by researchers. Here, we used a metabolic network mapping method called ambient air flow-assisted desorption electrospray ionization (AFADESI)-mass spectrometry imaging (MSI). We found the main changes in glycerophospholipid metabolism around the brain and sphingolipid metabolism changed mainly in the globus pallidus, which showed the most significant metabolite change after esketamine injection. The spatial distribution of metabolic changes was evaluated in the whole brain, and the potential mechanism of esketamine's antidepressant effect was explored in this research.

CircFhit Modulates GABAergic Synaptic Transmission via Regulating the Parental Gene Fhit Expression in the Spinal Dorsal Horn in a Rat Model of Neuropathic Pain.

Effective treatments for neuropathic pain are lacking due to our limited understanding of the mechanisms. The circRNAs are mainly enriched in the central nervous system. However, their function in various physiological and pathological conditions have yet to be determined. Here, we identified circFhit, an exon-intron circRNA expressed in GABAergic neurons, which reduced the inhibitory synaptic transmission in the spinal dorsal horn to mediate spared nerve injury-induced neuropathic pain. Moreover, we found that circFhit decreased the expression of GAD65 and induced hyperexcitation in NK1R+ neurons by promoting the expression of its parental gene Fhit in cis. Mechanistically, circFhit was directly bound to the intronic region of Fhit, and formed a circFhit/HNRNPK complex to promote Pol II phosphorylation and H2B monoubiquitination by recruiting CDK9 and RNF40 to the Fhit intron. In summary, we revealed that the exon-intron circFhit contributes to GABAergic neuron-mediated NK1R+ neuronal hyperexcitation and neuropathic pain via regulating Fhit in cis.

CircAnks1a in the spinal cord regulates hypersensitivity in a rodent model of neuropathic pain.

Circular RNAs are non-coding RNAs, and are enriched in the CNS. Dorsal horn neurons of the spinal cord contribute to pain-like hypersensitivity after nerve injury in rodents. Here we show that spinal nerve ligation is associated with an increase in expression of circAnks1a in dorsal horn neurons, in both the cytoplasm and the nucleus. Downregulation of circAnks1a by siRNA attenuates pain-like behaviour induced by nerve injury. In the cytoplasm, we show that circAnks1a promotes the interaction between transcription factor YBX1 and transportin-1, thus facilitating the nucleus translocation of YBX1. In the nucleus, circAnks1a binds directly to the Vegfb promoter, increases YBX1 recruitment to the Vegfb promoter, thereby facilitating transcription. Furthermore, cytoplasmic circAnks1a acts as a miRNA sponge in miR-324-3p-mediated posttranscriptional regulation of VEGFB expression. The upregulation of VEGFB contributes to increased excitability of dorsal horn neurons and pain behaviour induced by nerve injury. We propose that circAnks1a and VEGFB are regulators of neuropathic pain.