ASIC2b-dependent regulation of ASIC3, an essential acid-sensing ion channel subunit in sensory neurons via the partner protein PICK-1.

ASIC3, an acid-sensing ion channel subunit expressed essentially in sensory neurons, has been proposed to be involved in pain. We show here for the first time that native ASIC3-like currents were increased in cultured dorsal root ganglion (DRG) neurons following protein kinase C (PKC) stimulation. This increase was induced by the phorbol ester PDBu and by pain mediators, such as serotonin, which are known to activate the PKC pathway through their binding to G protein-coupled receptors. We demonstrate that this regulation involves the silent ASIC2b subunit, an ASIC subunit also expressed in sensory neurons. Indeed, heteromultimeric ASIC3/ASIC2b channels, but not homomeric ASIC3 channels, are positively regulated by PKC. The increase of ASIC3/ASIC2b current is accompanied by a shift in its pH dependence toward more physiological pH values and may lead to an increase of sensory neuron excitability. This regulation by PKC requires PICK-1 (protein interacting with C kinase), a PDZ domain-containing protein, which interacts with the ASIC2b C terminus.