Y FSLLRY-NH2, a selective PAR2 antagonist, in transfected CHO cells and DRG neurons. Nevertheless, neither PAR2-AP nor trypsin had an effect on ASIC3 currents in CHO cells expressing alone ASIC3, but not expressing PAR2. These results indicated that a functional interaction occurred amongst PAR2 and ASIC3. The present study showed that PAR2-AP potentiation of ASIC3 currents was blocked by intracellular dialysis of GDP–S, indicating that G proteins were involved in the intracellular mechanisms of this potentiation. PAR2 mostly couple the Gq11 subtype of G protein family, which activates PLC [1]. Lack from the potentiating effect in cells treated with PLC inhibitor U-73122 indicated a PLC-dependent pathway is predominantly involved in functional interaction in between PAR2 and ASIC3. On the list of consequences of PLC activation is the breakdown of PIP2 into DAG and inositol triphosphate, followed by mobilization of calcium and activation of PKC. Our observation that PKC inhibitor GF109203X also prevented the potentiation of ASIC3 currents by PAR2-AP indicated that activation of PKC played a major role in PAR2-induced sensitization of ASIC3. Similarly, electrophysiological studies have recommended that PAR2 sensitizes TRPV1, TRPV4, and TRPA1, which was blocked by a PLC inhibitor [14, 16, 18]. It has been shown that ASIC3 is modulated by proinflammatory mediators for instance serotonin and bradykinin by means of a PKC pathway [413]. We lately reported that Gq11-coupled metabotropic receptor activation for example glutamate (mGluRs), ATP (P2Y), and serotonin (5-HT2) receptors causes potentiation of ASICs inside a PKC-dependent manner in rat DRG neurons [346]. PAR2 has been located to sensitize TRPV1, TRPV4, and P2X3 ATP receptor in a PKC- and PKA-dependent manner [16, 37, 44]. Our observation that inhibition of PKA with H-89 reduced the potentiation of ASIC3 currents by PAR2-AP indicated that PKA also mediated PAR2-induced sensitization of ASIC3. It has been shown that heteromeric ASIC3ASIC2b channels, but not homomeric ASIC3 channels, are regulated by PKC and this regulation calls for PICK1 [42]. The present study showed that PAR2-induced sensitization of homomeric ASIC3 channels necessary simultaneous activation of PKC and PKA, due to the fact blocking either on the these kinases prevented the potentiation of ASIC3 currents by PAR2-AP. It remains to be determined irrespective of whether these kinases act sequentially or in parallel. The present study showed that PAR2-AP potentiated acidosis-evoked currents and membrane excitability indissociated rat DRG neurons, indicating that PAR2 activation also sensitized ASIC3 in rat sensory neurons. In constant with our prior report [346], a speedy reduction of extracellular pH evoked an ASIC3 existing in most native DRG neurons, since the proton-evoked currents were blocked by APETx2. Related to that observed in CHO cells co-expressing ASIC3 and PAR2, pre-application of PAR2-AP or trypsin also enhanced the proton-evoked currents through PAR2 in some DRG neurons sensitive to acidic stimuli. Lately, it has been reported that the activation of PAR2 enhances weak acid-induced ATP Linuron Biological Activity release by means of the sensitization of TRPV1 and ASIC3 in human esophageal epithelial cells [45]. Extracellular acidic stimuli open ASICs and mainly induce sodium influx, which can depolarize membrane potentials to the threshold of excitability and lead to bursts of action potentials. The current study showed that acidosis-evoked action potentials had been enhanced by PAR2-AP. The incr.
