079 Expression of protease-activated receptors and urokinase-type plasminogen activator receptor in epithelial and mesenchymal portion of human hair follicles

Takashi Anan, Tadashige Sonoda, Yuji Asada, Susumu Takayasu Department of Dermatology, Oita Medical University, Oita, Japan

(Background) Protease nexin-1 (PN1) is a potent inhibitor of serine protease including thrombin, urokinase-type plasminogen activator (u-PA) and trypsin. Its mRNA is expressed specifically by the dermal papilla during anagen. However, biological roles of PN1 in hair growth are still unclear. We hypothesized that PN1 controls signal transduction by thrombin and u-PA through their receptors, like in the platelet, vasculature and brain. In this study, we examined the expression of mRNA by RT-PCR for proteaseactivated receptors (PAR-1, 2 and 3) and u-PA receptor (u-PAR) in human scalp hair follicles which were dissected into upper and lower connective tissue sheath (UCTS and LCTS), dermal papilla (DP), and upper and lower epithelial compartments (UEC and LEC). PAR-1 and 3 are receptors for thrombin, and PAR-2 for trypsin and mast cell tryptase. (Result) The expression of mRNA of PAR-1 was detected in almost all mesenchymal compartments, namely in UCTS, LCTS and DP. PAR-3 was detected in UCTS or LCTS of some individuals. Neither PAR-1 nor PAR-3 was expressed in epithelial compartments. PAR-2 expression was not detected in any compartments of hair follicles. U-PAR was expressed in almost all compartments. These results suggest the possible role of PN1, which might inhibit thrombin and u-PA at their receptor level, although physiological roles of thrombin and urokinase in hair follicle are unknown.calp hair can be explained, at least in part, by down-regulation of basic FGF in hair follicle.