to proteolytic enzymes from many sources, including bacteria in the vaginal vault and immune cells in the lamina propria and subepithelium. Controlled proteolytic activity is thereby important for maintainance of normal tissue turnover and maintenance of this barrier. It is plausible that the V1 proteolytic activity may contribute to the pathophysiology of POP. A similar trypsinogen secreted from cancer cell lines, degrades subendothelial cell extracellular matrix and it has been shown that enzymes similar to PRSS3 degrade fibronectin and aggrecan. Recently, another serine A-1155463 protease termed HTRA1 with a highly conserved trypsin-like protease domain similar to PRSS3 was shown to alter Bruch��s Membrane composition in vivo and rHTRA1 lacking the N-terminal domain cleaved various extracellular matrix proteins, including fibronectin and fibulin-5. Here, we showed that PRSS3 also cleaved fibulin-5 in vitro. Thus, dysregulated V1 activity during the elastogenesis period may result in excessive cleavage of fibulin-5 and lead to disorganized elastic fibers in the vaginal wall. Since we have previously shown in order Indiplon Fbln52/2 vagina that elastic fibers connecting epidermis and stroma were loose and disrupted, it is fascinating to speculate that uninhibited trypsin-like proteases such as V1/ PRSS3 are involved in destruction of the integrity of connective tissues in subepidermis by cleaving fibulin-5 and other elastogenesis- associated ECM. Although loss of fibulin-5 after the completion of elastogenesis may not influence resting adult tissues, the continuous remodeling of the female reproductive tract during reproductive life which is accelerated after childbirth, and loss of fibulin-5-mediated inhibition of vaginal MMP-9 is predicted to have adverse effects on maintenance of vaginal connective tissues, especially postpartum when fibulin-5 protein levels return to baseline levels. Our findings showing that the imbalance between protease and protease inhibitors are associated with POP phenotype in mouse and human adds complexity to our understanding the pathogenesis of POP. We observed upregulation of MMP-9 as well as a trypsin-like serine protease in the Fbln52/2 vagina, and we confirmed that PRSS3 was indeed expressed in human vaginal tissues. Interestingly, in the human v
