Hair cycle-dependent expression of hepatocyte growth factor (HGF) activator, other proteinases, and proteinase inhibitors correlates with the expression of HGF in rat hair follicles

We previously reported that hepatocyte growth factor (HGF) had a stimulator y effect on hair growth in vivo and in vitro. The secreted inactive form of HGF is processed into an active form by serine proteinases such as HGF act ivator and urokinase, The mRNA expressions of various proteinases and their inhibitors in relation to HGF activation in hair growth were examined usin g animals with a synchronous hair cycle. Total RNA were extracted from the anterior dorsal skin of rats in different hair cycle stages, and mRNA expre ssions of the specific genes were compared using semiquantitative reverse t ranscription polymerase chain reaction. The mRNA of HGF, HGF activator, uro kinase, plasminogen activator inhibitor (PAI)-1, nexin-1, matrix metallopro teinase (MMP)-2, and tissue inhibitor of metalloproteinase (TIMP)-1 were ex pressed strongly in anagen tissue and slightly in telogen tissue. Moreover, topical application of 1% minoxidil sulfate to the anterior dorsal skin of rats in telogen stimulated hair growth and increased the mRNA expressions of HGF and MMP-2, These findings suggest that some proteinases and their in hibitors, strongly expressed in anagen, may act as hair growth regulatory m olecules, and may also be involved in processing the latent form of HGF.