Phospholipase C-Related but Catalytically Inactive Protein Modulates Pain Behavior in a Neuropathic Pain Model in Mice

Abstract

BackgroundAn inositol 1,4,5-trisphosphate binding protein, comprising 2 isoforms termed PRIP-1 and PRIP-2, was identified as a novel modulator for GABAA receptor trafficking. It has been reported that naive PRIP-1 knockout mice have hyperalgesic responses.FindingsTo determine the involvement of PRIP in pain sensation, a hind paw withdrawal test was performed before and after partial sciatic nerve ligation (PSNL) in PRIP-1 and PRIP-2 double knockout (DKO) mice. We found that naive DKO mice exhibited normal pain sensitivity. However, DKO mice that underwent PSNL surgery showed increased ipsilateral paw withdrawal threshold. To further investigate the inverse phenotype in PRIP-1 KO and DKO mice, we produced mice with specific siRNA-mediated knockdown of PRIPs in the spinal cord. Consistent with the phenotypes of KO mice, PRIP-1 knockdown mice showed allodynia, while PRIP double knockdown (DKD) mice with PSNL showed decreased pain-related behavior. This indicates that reduced expression of both PRIPs in the spinal cord induces resistance towards a painful sensation. GABAA receptor subunit expression pattern was similar between PRIP-1 KO and DKO spinal cord, while expression of K+-Cl--cotransporter-2 (KCC2), which controls the balance of neuronal excitation and inhibition, was significantly upregulated in DKO mice. Furthermore, in the DKD PSNL model, an inhibitor-induced KCC2 inhibition exhibited an altered phenotype from painless to painful sensations.ConclusionsSuppressed expression of PRIPs induces an elevated expression of KCC2 in the spinal cord, resulting in inhibition of nociception and amelioration of neuropathic pain in DKO mice.

Phospholipase C-related catalytically inactive protein (PRIP) controls KIF5B-mediated insulin secretion

“…Gabarap -siRNA (1, 2) (s80666, s80665) and Kif5b -siRNA (1, 2) (s68783, s68781) were from Life Technologies (Carlsbad, CA, USA). Mouse Prip1 -siRNAs (1, 2, 3) and Prip2 -siRNAs (1, 2, 3) were described previously ( Kitayama et al, 2013 ).…”

Enhanced lateral inhibition in the barrel cortex by deletion of phospholipase C-related catalytically inactive protein-1/2 in mice

“…5d), suggesting that GABA reuptake mechanism is not involved in the prolongation of the decay of eIPSCs/eIPSPs in PRIP-DKO PCs. On the other hand, it has been reported that the deletion of PRIP-1/2 causes changes in subunit composition of GABA A Rs: PRIP-DKO mice exhibited an increased expression of GABA A Rs containing α5 subunits in spinal neurons [9] and that of GABA A Rs containing α6 subunits in cerebellar granule neurons [14]. Indeed, in GABAergic neuron-HEK cell heterosynapses, an incorporation of α6 subunits into GABA A Rs caused a slow decay of IPSCs [23].…”

“…It is reported that in PRIP-DKO mice, the expressions of extrasynaptic GABA A Rs containing α5 and α6 subunits are increased by 25 % in spinal neurons [9] and by 10-30 % in cerebellar granule cells [14], respectively. Therefore, we next examined whether or not tonic GABA current differs between L3 PCs in the two genotypes.…”

The K+–Cl− Cotransporter KCC2 and Chloride Homeostasis: Potential Therapeutic Target in Acute Central Nervous System Injury

“…It is important to note that PNI also elicits activation of the BDNF-TrkB pathway in the dorsal horn neuron, which contributes to KCC2 down-regulation in these neurons and the occurrence of spinal nociception and injury-associated pain following PNI [106]. Inhibition of phospholipase C-related inactive protein (PRIP) expression induces an elevated expression of KCC2 that contributes to suppression of nociception and amelioration of neuropathic pain in PRIP-1 and PRIP-2 double knockdown mice [110].…”