Woodall, B. J. | Search bioRxiv

bioRxiv2025

Eukaryotic initiation factor 3d Regulates Context-Dependent Pain Hypersensitivity Through the Integrated Stress Response

Eukaryotic translation initiation factor 3 subunit D (eIF3d) is a noncanonical cap binding protein implicated in selective mRNA translation under stress conditions. Here, we investigate the contribution of eIF3d to pain processing using a heterozygous eIF3d knockout (eIF3d+/-) mouse model. We first validated this model, confirming substantial reductions in eIF3d mRNA and protein levels in dorsal root ganglia. Baseline assessments revealed no differences in mechanical, thermal, cold, or spontaneous pain behaviors between eIF3d+/- (HET) and eIF3d+/+ (WT) mice, indicating intact basal nociceptive function. In pain models involving peripheral inflammation and metabolic stress, including methylglyoxal injection, IL-6 administration and paw incision, HET mice displayed significantly reduced mechanical and cold hypersensitivity. In contrast, HET mice exhibited increased second phase nocifensive behavior in the formalin test, possibly indicating enhanced central sensitization. Hyperalgesic priming was comparable between HET and WT mice following IL-6 exposure. Experimental autoimmune encephalomyelitis (EAE) induced mice were unaffected by eIF3d reduction. These findings demonstrate that eIF3d selectively modulates nociceptive plasticity under defined stress conditions and suggests a context dependent role in the regulation of inflammatory and central pain sensitization. HighlightsO_LIBaseline mechanical, thermal, cold and spontaneous pain are intact in eIF3d+/-mice C_LIO_LIMethylglyoxal-evoked ISR activation and mechanical pain is blunted in eIF3d+/-mice C_LIO_LIIL-6-evoked mechanical and cold pain are reduced without altered priming C_LIO_LIMechanical hypersensitivity is reduced in eIF3d+/- mice with paw incision C_LIO_LIEAE pain is unaltered but increased pain in phase II formalin pain in eIF3d+/-mice C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=164 HEIGHT=200 SRC="FIGDIR/small/695844v1_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@26d9aforg.highwire.dtl.DTLVardef@9d7350org.highwire.dtl.DTLVardef@fdbabeorg.highwire.dtl.DTLVardef@1ef1074_HPS_FORMAT_FIGEXP M_FIG C_FIG

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bioRxiv2023

Diroximel fumarate acts through Nrf2 to attenuate methylglyoxal-induced nociception in mice and decreases ISR activation in DRG neurons

Diabetic neuropathic pain is associated with elevated plasma levels of methylglyoxal (MGO). MGO is a metabolite of glycolysis that causes mechanical hypersensitivity in mice by inducing the integrated stress response (ISR), which is characterized by phosphorylation of eukaryotic initiation factor 2 (p-eIF2). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates the expression of antioxidant proteins that neutralize MGO. We hypothesized that activating Nrf2 using diroximel fumarate (DRF) would alleviate MGO-induced pain hypersensitivity. We pretreated male and female C57BL/6 mice daily with oral DRF prior to intraplantar injection of MGO (20 ng). DRF (100 mg/kg) treated animals were protected from developing MGO-induced mechanical and cold hypersensitivity. Using Nrf2 knockout mice we demonstrate that Nrf2 is necessary for the anti-nociceptive effects of DRF. In cultured mouse and human dorsal root ganglion (DRG) sensory neurons, we found that MGO induced elevated levels of p-eIF2. Co-treatment of MGO (1 {micro}M) with monomethyl fumarate (MMF, 10, 20, 50 {micro}M), the active metabolite of DRF, reduced p-eIF2 levels and prevented aberrant neurite outgrowth in human DRG neurons. Our data show that targeting the Nrf2 antioxidant system with DRF is a strategy to potentially alleviate pain associated with elevated MGO levels. PerspectiveThis study demonstrates that activating Nrf2 with DRF prevents the development of pain caused by MGO in mice and reduces ISR in mouse and human DRG in vitro models. We propose that Nrf2 activators like DRF should be tested to alleviate diabetic neuropathic pain associated with elevated MGO in patients. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/572877v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@5e0703org.highwire.dtl.DTLVardef@11e95bforg.highwire.dtl.DTLVardef@f92f2borg.highwire.dtl.DTLVardef@187f12d_HPS_FORMAT_FIGEXP M_FIG C_FIG Article HighlightsO_LIMGO induces mechanical and cold hypersensitivity in mice that is prevented with pre-treatment with DRF. C_LIO_LIDRF pre-treatment does not protect Nrf2-knockout mice from developing pain hypersensitivity suggesting that Nrf2 is necessary for DRFs antinociceptive effects. C_LIO_LIMMF, the active metabolite of DRF, prevents MGO-induced increase in p-eIF2a levels in mouse and human DRG neurons in vitro. C_LIO_LIMMF prevents MGO-induced aberrant neurite outgrowth in human DRG neurons. C_LIO_LINrf2 activators, like the FDA-approved DRF, is an option to alleviate neuropathic pain in patients with diabetes. C_LI

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