TY - JOUR
T1 - Conditional knockout of CRMP2 in neurons, but not astrocytes, disrupts spinal nociceptive neurotransmission to control the initiation and maintenance of chronic neuropathic pain
AU - Boinon, Lisa
AU - Yu, Jie
AU - Madura, Cynthia L.
AU - Chefdeville, Aude
AU - Feinstein, Douglas L.
AU - Moutal, Aubin
AU - Khanna, Rajesh
N1 - Funding Information:
The study allowed us to narrow the role of CRMP2 to glutamatergic transmission in the spinal cord. This is supported by several salient findings. First, the suppression of CRMP2 expression decreased sEPSC frequency and amplitude in rats and mice. Second, there was no effect on sIPSCs recorded from superficial dorsal horn neurons in acute spinal cord slices. Third, no effect was noted on mEPSCs and mIPSCs. Single-cell RNA-seq studies found negligible traces of CRMP2 (dpysl2) transcripts in GABAergic neurons in the spinal cord, thus supporting our findings of CRMP2's action being restricted to glutamatergic synapses in the SDH. Miniature currents are recorded in the presence of TTX, a blocker of VGSCs, which allows for the separation of neurotransmitter release from presynaptic activity. A postsynaptic action of CRMP2 would have been supported by a diminution of the amplitude of the miniature currents. Nevertheless, the impact of loss of CRMP2 on sEPSC amplitude is significant. This may be explained by an atypical function of CRMP2 as a neurotransmitter. Collapsin response mediator protein 2 can be released from injured nerves and directly activate NMDA receptors. These receptors are localized both presynaptically and postsynaptically in the SDH. Loss of their activation through extracellular CRMP2 may account for at least part of the decreased frequency and amplitude of sEPSCs observed in our studies. Thus, a reasonable inference from our findings is that CRMP2 function is limited to the presynaptic sites of the SDH.
Publisher Copyright:
© 2021 International Association for the Study of Pain
PY - 2022/2/1
Y1 - 2022/2/1
N2 - Mechanistic studies principally focusing on primary afferent nociceptive neurons uncovered the upregulation of collapsin response mediator protein 2 (CRMP2)-a dual trafficking regulator of N-type voltage-gated calcium (Cav2.2) as well as Nav1.7 voltage-gated sodium channels-as a potential determinant of neuropathic pain. Whether CRMP2 contributes to aberrant excitatory synaptic transmission underlying neuropathic pain processing after peripheral nerve injury is unknown. Here, we interrogated CRMP2's role in synaptic transmission and in the initiation or maintenance of chronic pain. In rats, short-interfering RNA-mediated knockdown of CRMP2 in the spinal cord reduced the frequency and amplitude of spontaneous excitatory postsynaptic currents, but not spontaneous inhibitory postsynaptic currents, recorded from superficial dorsal horn neurons in acute spinal cord slices. No effect was observed on miniature excitatory postsynaptic currents and inhibitory postsynaptic currents. In a complementary targeted approach, conditional knockout of CRMP2 from mouse neurons using a calcium/calmodulin-dependent protein kinase II alpha promoter to drive Cre recombinase expression reduced the frequency and amplitude of spontaneous excitatory postsynaptic currents, but not miniature excitatory SCss. Conditional knockout of CRMP2 from mouse astrocytes using a glial fibrillary acidic protein promoter had no effect on synaptic transmission. Conditional knockout of CRMP2 in neurons reversed established mechanical allodynia induced by a spared nerve injury in both male and female mice. In addition, the development of spared nerve injury-induced allodynia was also prevented in these mice. Our data strongly suggest that CRMP2 is a key regulator of glutamatergic neurotransmission driving pain signaling and that it contributes to the transition of physiological pain into pathological pain.
AB - Mechanistic studies principally focusing on primary afferent nociceptive neurons uncovered the upregulation of collapsin response mediator protein 2 (CRMP2)-a dual trafficking regulator of N-type voltage-gated calcium (Cav2.2) as well as Nav1.7 voltage-gated sodium channels-as a potential determinant of neuropathic pain. Whether CRMP2 contributes to aberrant excitatory synaptic transmission underlying neuropathic pain processing after peripheral nerve injury is unknown. Here, we interrogated CRMP2's role in synaptic transmission and in the initiation or maintenance of chronic pain. In rats, short-interfering RNA-mediated knockdown of CRMP2 in the spinal cord reduced the frequency and amplitude of spontaneous excitatory postsynaptic currents, but not spontaneous inhibitory postsynaptic currents, recorded from superficial dorsal horn neurons in acute spinal cord slices. No effect was observed on miniature excitatory postsynaptic currents and inhibitory postsynaptic currents. In a complementary targeted approach, conditional knockout of CRMP2 from mouse neurons using a calcium/calmodulin-dependent protein kinase II alpha promoter to drive Cre recombinase expression reduced the frequency and amplitude of spontaneous excitatory postsynaptic currents, but not miniature excitatory SCss. Conditional knockout of CRMP2 from mouse astrocytes using a glial fibrillary acidic protein promoter had no effect on synaptic transmission. Conditional knockout of CRMP2 in neurons reversed established mechanical allodynia induced by a spared nerve injury in both male and female mice. In addition, the development of spared nerve injury-induced allodynia was also prevented in these mice. Our data strongly suggest that CRMP2 is a key regulator of glutamatergic neurotransmission driving pain signaling and that it contributes to the transition of physiological pain into pathological pain.
KW - CRMP2
KW - Conditional knockout
KW - Mechanical allodynia
KW - Synaptic transmission
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UR - http://www.scopus.com/inward/citedby.url?scp=85123461518&partnerID=8YFLogxK
U2 - 10.1097/j.pain.0000000000002344
DO - 10.1097/j.pain.0000000000002344
M3 - Article
C2 - 35029600
AN - SCOPUS:85123461518
SN - 0304-3959
VL - 163
SP - E368-E381
JO - Pain
JF - Pain
IS - 2
ER -