Targeted transcriptional upregulation of SENP1 by CRISPR activation enhances deSUMOylation pathways to elicit antinociception in the spinal nerve ligation model of neuropathic pain

The voltage-gated sodium channel Na_V1.7 is an essential component of human pain signaling. Changes in Na_V1.7 trafficking are considered critical in the development of neuropathic pain. SUMOylation of collapsin response mediator protein 2 (CRMP2) regulates the membrane trafficking and function of Na_V1.7. Enhanced CRMP2 SUMOylation in neuropathic pain correlates with increased Na_V1.7 activity. Pharmacological and genetic interventions that interfere with CRMP2 SUMOylation in rodents with neuropathic pain have been shown to reverse mechanical allodynia. Sentrin or SUMO-specific proteases (SENPs) are vital for balancing SUMOylation and deSUMOylation of substrates. Overexpression of SENP1 and/or SENP2 in CRMP2-expressing cells results in increased deSUMOylation and decreased membrane expression and currents of Na_V1.7. Although SENP1 is present in the spinal cord and dorsal root ganglia, its role in regulating Na_V1.7 function and pain is not known. We hypothesized that favoring SENP1 expression can enhance CRMP2 deSUMOylation to modulate Na_V1.7 channels. In this study, we used a clustered regularly interspaced short palindromic repeats activation (CRISPRa) SENP1 lentivirus to overexpress SENP1 in dorsal root ganglia neurons. We found that SENP1 lentivirus reduced CRMP2 SUMOylation, Na_V1.7-CRMP2 interaction, and Na_V1.7 membrane expression. SENP1 overexpression decreased Na_V1.7 currents through clathrin-mediated endocytosis, directly linked to CRMP2 deSUMOylation. Moreover, enhancing SENP1 expression did not affect the activity of TRPV1 channels or voltage-gated calcium and potassium channels. Intrathecal injection of CRISPRa SENP1 lentivirus reversed mechanical allodynia in male and female rats with spinal nerve injury. These results provide evidence that the pain-regulating effects of SENP1 overexpression involve, in part, the modulation of Na_V1.7 channels through the indirect mechanism of CRMP2 deSUMOylation.