First Hospital of China Medical University

This study investigates the mechanism of the TRPV1 channel in neuropathic pain (NP), focusing on the c/EBPβ/Uchl3/TRPV1 axis and mitochondrial dynamics. Using male rats chronic constriction injury (CCI) model and an LPS-induced dorsal root ganglion (DRG) cell model, we measured paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL), assessed expression changes of related molecules via Real-time quantitative reverse transcription PCR (RT-qPCR) and Western blot, observed mitochondrial fission via transmission electron microscopy (TEM) and Tomm20 immunofluorescence, evaluated mitochondrial function via JC-1 and MitoSOX, and examined neuronal excitability via calcium imaging. Co-immunoprecipitation (Co-IP) confirmed Uchl3-TRPV1 binding, and ubiquitination assay combined with Cycloheximide (CHX) chase and proteasome inhibition assays demonstrated that Uchl3 inhibits TRPV1 degradation via deubiquitination. Luciferase and Chromatin immunoprecipitation (ChIP) assays verified c/EBPβ as a transcriptional activator of Uchl3. Results showed that TRPV1 activation promoted mitochondrial fission, dysfunction, and neuronal excitability, driving NP. Uchl3 stabilized TRPV1 by removing its ubiquitination, altering mitochondrial dynamics. c/EBPβ transcriptionally upregulated Uchl3, forming a regulatory cascade. Intrathecal si-c/EBPβ in CCI rats downregulated c/EBPβ, Uchl3, and TRPV1, restored mitochondrial homeostasis, and alleviated pain behavior. In conclusion, the c/EBPβ/Uchl3/TRPV1 pathway regulates NP through mitochondrial dynamics in male rats, presenting a novel therapeutic target for NP treatment.

Sonic hedgehog subgroup medulloblastoma (SHH-MB), an aggressive pediatric brain tumor that originates from granule neuron precursors, faces the challenge of poor treatment owing to its unclear molecular mechanisms. Here, we show that sialic acid-binding immunoglobulin-like receptor 15 (Siglec-15), an immunosuppressive membrane protein, is upregulated and mediates SHH-MB growth through its translocation to the lysosomal membrane. We found that SHH-MB cells use the cation-independent mannose 6-phosphate receptor (CI-MPR) to transport Siglec-15 from the trans-Golgi network (TGN) to lysosomes, where Siglec-15 induces lysosomal Ca2+ release by interacting with mucolipin TRP cation channel 1 (TRPML1), leading to the nuclear translocation of the transcription factor EB (TFEB). Blockade of Siglec-15, TRPML1, or TFEB hinders SHH-MB growth in vitro and in vivo. Importantly, aryl hydrocarbon receptor (AhR), a cytoplasmic transcription factor, upregulates Siglec-15 expression. AhR inhibition by CH-223191 or StemRegenin 1 (SR1) achieved therapeutic efficacy against orthotopic SHH-MB xenografts in mice. These findings reveal an essential role for the AhR-Siglec-15 axis in SHH-MB development, providing a potential strategy for SHH-MB treatment.