抄録
TRPV3 and TRPV4 are heat-activated cation channels expressed in keratinocytes. It has been proposed that heat-activation of TRPV3 and/or TRPV4 in the skin may release diffusible molecules which would then activate termini of neighboring dorsal root ganglion (DRG) neurons. Here, using in vitro co-culture systems, we show that ATP is such a candidate molecule released from keratinocytes upon heating (– 40°C). Using TRPV1 deficient DRG neurons, we show that increase in cytosolic Ca2+-concentration in DRG neurons upon heating was observed only when neurons were co-cultured with keratinocytes, and this increase was blocked by PPADS (100 μM), a P2 purinoreceptor antagonist. In a co-culture of keratinocytes with HEK293 cells (transfected with P2X2 cDNA to serve as a bio-sensor), we show that heat-activation of keratinocytes secretes ATP, and that ATP release is compromised in keratinocytes from TRPV3 deficient mice. Release of serotonin and gulutamate was denied using the co-culture system with HEK293 cells expressing 5-HT3 and NMDA receptors, respectively. ATP-induced whole-cell currents were also observed in the co-culture of mouse keratinocytes and DRG neurons. This study provides direct evidence that ATP is a messenger molecule for TRPV3-mediated thermotransduction in skin. [J Physiol Sci. 2007;57 Suppl:S99]
