Gonadotrophin regulation of production of tissue inhibitor of metalloproteinases-1 by luteinized human granulosa cells: a potential mechanism for luteal rescue

Abstract

Human granulosa cells were maintained in culture with extracellular matrix in the presence or absence of human chorionic gonadotrophin (HCG) using a defined culture medium. Such cultures are maintained by gonadotrophin in a manner suggesting that features of 'luteal rescue' may be occurring in vitro. Western analysis of culture medium demonstrated that the granulosa cells produced tissue inhibitor of metalloproteinases (TIMP)-1 but not TIMP-2. The presence of TIMP-1 in cultured cells was also detected immunocytochemically. Immunoassay of TIMP-1 output revealed that HCG exposure for 7 days caused a 2-fold increase in TIMP-1 production versus control reaching maximum at approximately 1 ng HCG/ml. The sensitivity of this response to HCG was similar to that observed for stimulation of progesterone production. Delayed addition of HCG, from day 4 of culture, elicited increases in TIMP-1 which were evident within 24 hours, and were not explained by changes in cell replication or survival. Removal of HCG from cultures previously luteinized with HCG for 6 days resulted in a fall in TIMP-1 production. Thus TIMP-1 production by luteinized granulosa cells in culture is gonadotrophin dependent. We speculate that prolonged cellular function associated with 'luteal rescue' may result from increased extracellular matrix stability mediated by up-regulation of TIMP-1 production.

Membrane-bound carboxypeptidase-M is expressed on human ovarian follicles and corpora lutea of menstrual cycle and early pregnancy

“…We have reported that the membrane-bound aminopeptidases expressed on ovarian cells are involved in ovarian cell function and differentiation by regulating the extracellular peptide concentrations (Fujiwara et al, 1992a,b;Nakamura et al, 1996;Tachibana et al, 1996). Recently matrix metalloproteinases and their inhibitor, named the tissue inhibitor of metalloproteinases, are also reported to regulate ovarian function as local regulators of the ovary (Hulboy et al, 1997;O'Sullivan et al, 1997). Similarly, CP-M can be proposed as a local regulator of granulosa and theca cell function, which regulates biologically active peptide concentrations by the removal of carboxy-terminal basic amino acids from these peptides.…”

ATP-induced apoptosis of human granulosa luteal cells cultured in vitro

“…It is also well established that when gonadotropins, such as LH, FSH, and hCG, added to human granulosa luteal cells in culture affect luteal function through control of apoptosis (47). The role of hCG in luteal rescue has been attributed to up-regulation of a tissue inhibitor of metalloproteinase by human granulosa luteal cells (48) or down-regulation of P 2Y receptor message in human granulosa luteal cells (49). In either case, continued presence of hCG during early pregnancy could prevent human granulosa luteal cells from entering into apoptosis, thereby possibly leading to maintenance of secretion of steroids from the rescued corpus luteum.…”

The human corpus luteum: remodelling during luteolysis and maternal recognition of pregnancy

“…Indeed, there is some supporting evidence for this hypothesis. Induced luteolysis resulted in decreased TIMP-1 expression in the corpus luteum of non-human primates (Duncan et al, 1996a) and hCG increased TIMP-1 expression in luteinized granulosa cells in vitro (O'Sullivan et al, 1997). However, in cows, induced luteolysis increased the concentrations of TIMP-1, in contrast to the normal luteal phase, where expression tended to decrease (Smith et al, 1996).…”