Functional roles of cell surface peptidases in reproductive organs.

A number of biologically active peptides have been proposed to regulate function and differentiation of reproductive organs in an autocrine and/or paracrine fashion. Regulation of the local concentrations of these peptides is one of the important factors influencing their physiological effects on target cells. Membrane-bound cell surface peptidases can activate or inactivate biologically active peptides before peptide factors access their receptors on the cell surface. Aminopeptidase A (EC 3.4.11.7), placental leucine aminopeptidase (EC 3.4.11.3), aminopeptidase-N/CD13 (EC 3.4.11.2), dipeptidyl peptidases IV/CD26 (EC.3.4.14.5), carboxypeptidase-M (EC 3.4.17.12), neutral endopeptidase/CD10 (EC 3.4.24.11) and endothelin converting enzyme-1 (EC 3.4.23) are differentially expressed on the ovary, endometrium and placenta. The inhibition of enzyme activity affects steroid hormone production by granulosa and thecal cells, decidualization of endometrium and migration of extravillous trophoblasts. These findings suggest that membrane-bound cell surface peptidases are local regulators for cellular growth and differentiation in reproductive organs by controlling extracellular concentration of peptide factors. (Reprod Med Biol 2004; 3: 165 -176).