Effects of insulin-like growth factors and binding protein 1 on bovine granulosa cell division in anchorage-independent culture

Abstract

5). An increase in the number of cells in the presence of IGF-I was also confirmed by DNA measurement (P < 0.05, n = 5) and by western immunoblotting analyses of La antigen (n = 3). IGFBP-1 significantly inhibited cell division stimulated by IGF-I (P < 0.001) and IGF-II (P < 0.001), but not that stimulated by the analogue, LR3IGF-I, which has low affinity for IGFBPs. Other factors also known to affect IGF synthesis or effectiveness (FSH, oestradiol, growth hormone) did not appear to influence division of granulosa cells when cultured under anchorage-independent conditions, while dibutyryl cAMP significantly inhibited cell division (P < 0.01, n = 5). In (Adashi et al, 1991). Furthermore, these cells can produce specific IGF-binding proteins (IGFBPs) (Hsu and Hammond, 1987;Ramasharma and Li, 1987;Voutilainen and Miller, 1987;Mondschein et al, 1990;Adashi et al, 1991;Stanko et al, 1994). (Koistinen et al, 1990) and that these cells synthesize and secrete IGFBP-1 (Suikkari et al, 1989 Correspondence.Received 5 January 1996. mitotic index first increasing and then decreasing (Lussier et al, 1987 Materials and Methods Isolation of granulosa cellsThe procedure for the isolation of bovine granulosa cells and their subsequent culture under anchorage-independent con¬ ditions used in this study was a modification of the method described by (Fig. 1) (Fig. 1). IGF-I enhanced the rate above that of controls after 48 h of culture (Fig. 1) (Fig. 2) [3H]thymidine incorporation are shown (Fig. 3) (Francis et al, 1992), was examined. IGFBP-1 had no effect on the stimulatory effect of longR3IGF-I (108 ± 10% of the mean ± sem concentrations observed with longR3IGF-I alone, = 3), suggesting that the inhibitory effect of IGFBP-I on IGF-stimulated cell division was via its ability to bind IGF-I. In another set of experiments (Fig. 4), IGF-I increased the total content of DNA (per dish) but the effect was not significant.

Morphological Characterization of Bovine Primordial Follicles and their Environment in Vivo1

“…Our recent observations go further than the suggestion that not all granulosa cells have equipotential for mitosis; they suggest that there may be a population of stem cells in each follicle. Certainly a proportion of granulosa cells exhibit some of the properties of stem cells-mitosis is not inhibited by cell contact in vivo and mitosis is not dependent upon anchorage in vitro [30,42,43]. Thus, the fate and properties of the 24 granulosa cells in primordial follicles has still to be determined.…”

Effects of α-enolase gene silencing on reproductive-related hormone receptor expression and steroid hormone synthesis of primary granulosa cells from goose F1 follicles

“…IGF-1 may be an important regulator of follicular granulosa cells maintaining their sensitivity to LH and FSH. IGFBP-1 is synthesised and secreted in human ovarian granulosa cells, which regulate IGF-1-mediated biological effects by modulating serum IGF-1 concentration (11). In the present study, the expression of IGFBP-1 mRNA decreased after ENO1 interference, indicating that its binding capacity to and inhibitory effect on IGF-1 decreased, thus indirectly leading to oestrogen secretion.…”

The Clinical Application of Growth Hormone and Its Biological and Molecular Mechanisms in Assisted Reproduction

“…An in vitro study also confirmed that the inhibition of IGF1 signaling restored GH-induced stimulation of FSH-induced progesterone production, which suggested that endogenous IGF1 could be functionally involved with the effects of GH on progesterone production [140]. The biological effects of IGF1 have been further demonstrated to be mediated by IGF1 binding proteins, which are synthesized and secreted in human ovarian GCs [162]. Interestingly, increased free IGF1 has been demonstrated to decrease the synthesis of IGF2R, thereby allowing for more IGF2 to be bioavailable (free) for the induction of steroidogenesis and mitogenesis via the IGF1R [163].…”