PKC-NF-κB are involved in CCL2-induced Nav1.8 expression and channel function in dorsal root ganglion neurons.
CCL2 [chemokine (C-C motif) ligand 2] contributes to the inflammation-induced neuropathic pain through activating VGSC (voltage-gated sodium channel)-mediated nerve impulse conduction, but the underlying mechanism is currently unknown. Our study aimed to investigate whether PKC (protein kinase C)-NF-κB (nuclear factor κB) is involved in CCL2-induced regulation of voltage-gated sodium Nav1.8 currents and expression. DRG (dorsal root ganglion) neurons were prepared from adult male Sprague-Dawley rats and incubated with various concentration of CCL2 for 24 h. Whole-cell patch-clamps were performed to record the Nav1.8 currents in response to the induction by CCL2. After being pretreated with 5 and10 nM CCL2 for 16 h, CCR2 [chemokine (C-C motif) receptor 2] and Nav1.8 expression significantly increased and the peak currents of Nav1.8 elevated from the baseline 46.53±4.53 pA/pF to 64.28±3.12 pA/pF following 10 nM CCL2 (P<0.05). Compared with the control, significant change in Nav1.8 current density was observed when the CCR2 inhibitor INCB3344 (10 nM) was applied. Furthermore, inhibition of PKC by AEB071 significantly eliminated CCL2-induced elevated Nav1.8 currents. In vitro PKC kinase assays and autoradiograms suggested that Nav1.8 within DRG neurons was a substrate of PKC and direct phosphorylation of the Nav1.8 channel by PKC regulates its function in these neurons. Moreover, p65 expression was significantly higher in CCL2-induced neurons (P<0.05), and was reversed by treatment with INCB3344 and AEB071. PKC-NF-κB are involved in CCL2-induced elevation of Nav1.8 current density by promoting the phosphorylation of Nav1.8 and its expression.
*Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
Rui
R
Zhao
*Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
Guo-Xian
GX
Pei
*Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
Rui
R
Cong
*Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
Hang
H
Zhang
*Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
Cheng-Wu
CW
Zang
*Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
Tong
T
Tian
D000818:Animals; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D017136:Ion Transport / Q000502:physiology; D008297:Male; D062559:NAV1.8 Voltage-Gated Sodium Channel / Q000096:biosynthesis*; D009474:Neurons / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051996:Transcription Factor RelA / Q000096:biosynthesis*
C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D062559:NAV1.8 Voltage-Gated Sodium Channel; C498145:Rela protein, rat; C568319:Scn10a protein, rat; D051996:Transcription Factor RelA; D011493:Protein Kinase C