Rab7—a novel redox target that modulates inflammatory pain processing

Abstract

Chronic pain is accompanied by production of reactive oxygen species (ROS) in various cells that are important for nociceptive processing. Recent data indicate that ROS can trigger specific redox-dependent signaling processes, but the molecular targets of ROS signaling in the nociceptive system remain largely elusive. Here, we performed a proteome screen for pain-dependent redox regulation using an OxICAT approach, thereby identifying the small GTPase Rab7 as a redox-modified target during inflammatory pain in mice. Prevention of Rab7 oxidation by replacement of the redox-sensing thiols modulates its GTPase activity. Immunofluorescence studies revealed Rab7 expression to be enriched in central terminals of sensory neurons. Knockout mice lacking Rab7 in sensory neurons showed normal responses to noxious thermal and mechanical stimuli; however, their pain behavior during inflammatory pain and in response to ROS donors was reduced. The data suggest that redox-dependent changes in Rab7 activity modulate inflammatory pain sensitivity.

FOXO3/Rab7-Mediated Lipophagy and Its Role in Zn-Induced Lipid Metabolism in Yellow Catfish (Pelteobagrus fulvidraco)

“…NRF2 and STAT3 are key regulators of cellular antioxidant and immune responses. Our results suggested that rab7 may be essential for maintaining the antioxidant and immune balance, as supported by other studies [ 46 , 47 , 48 , 49 , 50 ]. Most importantly, we predicted multiple FOXO3 transcription factor binding sites in the rab7 promoter region ( Figure 2 ), confirming our initial hypothesis.…”

Rab27a Contributes to the Processing of Inflammatory Pain in Mice

“…Zymosan- and Complete Freund′s Adjuvant (CFA)-induced paw inflammation. Induction of paw inflammation by zymosan and CFA has been described previously [ 6 , 36 ]. Briefly, 15 µL of a zymosan A suspension (5 mg/mL in 0.1 M PBS, pH 7.4; Sigma-Aldrich, Steinheim, Germany) or 20 µL of complete Freund‘s adjuvant (CFA; containing 1 mg/mL heat-killed Mycobacterium tuberculosis in paraffin oil 85% and mannide monooleate 15%; Sigma-Aldrich) was injected into the plantar subcutaneous space of a hind paw [ 37 ].…”

“…Tissue preparation and immunofluorescence staining were performed as described previously [ 6 , 31 , 36 ]. Shortly, mice were intracardially perfused with 4% paraformaldehyde in PBS (pH 7.4) and the lumbar spinal cord (L4–L5) and dorsal root ganglia (DRGs) (L4–L6) were dissected, post-fixed, and cryoprotected in 20% sucrose overnight.…”

“…Tissue was then incubated in 20% sucrose in PBS at 4 • C overnight, embedded in tissue freezing medium (Leica, Wetzlar, Germany), and cryostat sections were cut at a thickness of 14 µm and stored at −80 • C. In situ hybridization (ISH) was performed using an QuantiGene ViewRNA Tissue Assay (Thermo Fisher Scientific, Frankfurt, Germany). Experiments were performed according to the instructions of the manufacturer and included extensive washing steps as described previously [6]. Probes specific for mouse Rab27a (catalog # VB1-3028872, Thermo Fisher, NCBI # NM_001301230.1) and scramble control for type 1 (catalog # VF1-17155) were incubated overnight at 40 • C (Thermobrite, Leica, Wetzlar, Germany).…”

“…More than 60 Rab proteins have been identified, which are involved in basic cellular processes such as cellular trafficking, vesicular trafficking and synaptic plasticity. In a previous study, we found that Rab7 contributes to the processing of inflammatory pain in a redox-dependent manner [ 6 ]. Moreover, expression of Rab7 is upregulated after peripheral nerve injury [ 7 ] and Rab7-mediated lysosomal targeting of µ-opioid receptors leads to a loss in opioid antinociception in diabetic neuropathic pain [ 8 ].…”