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Ovarian transforming growth factor-beta (TGF beta): cellular site(s), and mechanism(s) of action
E Y Adashi1, C E Resnick, E R Hernandez
1Department of Obstetrics/Gynecology, University of Maryland School of Medicine, Baltimore 21201.
Abstract:
It is the objective of the experiments reported herein to examine the possible relevance of transforming growth factor-beta (TGF beta) to theca-interstitial cell function, and to further characterize the established interaction of TGF beta with the granulosa cell. In examining the interaction of TGF beta (10 ng/ml) with murine theca-interstitial cells, no significant effect was observed on either basal or human chorionic gonadotropin (hCG)-stimulated androsterone accumulation. In contrast, given murine granulosa cells, TGF beta (10 ng/ml) produced dose- and time-dependent augmentation of follicle-stimulating hormone (FSH)-supported aromatase activity with a minimal and median effective doses of 20 +/- 3 and 123 +/- 24 pg/ml, respectively and a minimal time requirement of less than or equal to 48 h. The ability of TGF beta to augment FSH hormonal action could not be accounted for by alteration(s) of specific FSH binding (13965 +/- 298 and 12614 +/- 694 cpm/4 X 10(5) cells for FSH and FSH + TGF beta). However, TGF beta proved capable of exerting a direct upregulatory effect on stimulatable adenylate cyclase activity, further enhancement occurring at site(s) distal to cAMP generation (dibutyryl cyclic AMP (Bt2cAMP) = 1.4 +/- 0.2 ng/culture; Bt2cAMP + TGF beta = 4.1 +/- 0.6 ng/culture). Taken together, our findings are in keeping with the notion that TGF beta, possibly of intraovarian origin, comprises the central signal of autocrine or paracrine loop(s) capable of amplifying gonadotropin action at the level of the granulosa, but not theca-interstitial cell.
Insights
Transforming growth factor-beta (TGF beta) amplifies follicle-stimulating hormone (FSH) action in granulosa cells but not theca-interstitial cells. This suggests TGF beta plays a key role in ovarian paracrine signaling to enhance gonadotropin effects.
Area of Science:
- Reproductive biology
- Endocrinology
- Cell signaling
Background:
- Transforming growth factor-beta (TGF beta) is a key signaling molecule in the ovary.
- Its precise role in theca-interstitial and granulosa cell function requires further elucidation.
- Understanding TGF beta's interaction with gonadotropins is crucial for reproductive health research.
Purpose of the Study:
- To investigate the role of TGF beta in theca-interstitial cell function.
- To further characterize the interaction between TGF beta and granulosa cells.
- To determine the mechanism by which TGF beta influences FSH action.
Main Methods:
- Murine theca-interstitial and granulosa cells were cultured.
- Cells were treated with TGF beta and/or human chorionic gonadotropin (hCG) or follicle-stimulating hormone (FSH).
- Androsterone accumulation, aromatase activity, FSH binding, and adenylate cyclase activity were measured.
Main Results:
- TGF beta did not affect basal or hCG-stimulated androsterone accumulation in theca-interstitial cells.
- TGF beta dose- and time-dependently augmented FSH-supported aromatase activity in granulosa cells.
- TGF beta directly upregulated adenylate cyclase activity and downstream signaling.
Conclusions:
- TGF beta amplifies FSH action in granulosa cells, but not theca-interstitial cells.
- TGF beta may act as an intraovarian signal in autocrine or paracrine loops.
- This action enhances gonadotropin signaling within the ovary.