Growth differentiation factor 9 (GDF9) stimulates proliferation and inhibits steroidogenesis by bovine theca cells: influence of follicle size on responses to GDF9.

Ovarian follicular development is controlled by numerous paracrine and endocrine regulators, including oocyte-derived growth differentiation factor 9 (GDF9), and a localized increase in bioavailable insulin-like growth factor 1 (IGF1). The effects of GDF9 on function of theca cells collected from small (3-6 mm) and large (8-22 mm) ovarian follicles were investigated. In small-follicle theca cells cultured in the presence of both LH and IGF1, GDF9 increased cell numbers and DNA synthesis, as measured by a (3)H-thymidine incorporation assay, and dose-dependently decreased both progesterone and androstenedione production.

Overview of steroidogenic enzymes in the pathway from cholesterol to active steroid hormones.

Significant advances have taken place in our knowledge of the enzymes involved in steroid hormone biosynthesis since the last comprehensive review in 1988. Major developments include the cloning, identification, and characterization of multiple isoforms of 3beta-hydroxysteroid dehydrogenase, which play a critical role in the biosynthesis of all steroid hormones and 17beta-hydroxysteroid dehydrogenase where specific isoforms are essential for the final step in active steroid hormone biosynthesis. Advances have taken place in our understanding of the unique manner that determines tissue-specific expression of P450aromatase through the utilization of alternative promoters.

Transcription enhancer factor-5 and a GATA-like protein determine placental-specific expression of the Type I human 3beta-hydroxysteroid dehydrogenase gene, HSD3B1.

The enzyme 3beta-hydroxysteroid dehydrogenase/isomerase (3betaHSD) is required for the biosynthesis of all active steroid hormones. It exists as multiple isoforms in humans and rodents, each a product of a distinct gene. Two isoforms, 3betaHSD I and II, are expressed in a tissue-specific manner in humans.

Proplatelet formation of megakaryocytes is triggered by autocrine-synthesized estradiol.

A matured megakaryocyte releases thousands of platelets through a drastic morphological change, proplatelet formation (PPF). The megakaryocyte/erythrocyte-specific transcription factor, p45 NF-E2, is essential for initiating PPF, but the factor regulating PPF has not been identified. Here we report that estradiol synthesized in megakaryocytes triggers PPF.

Müllerian inhibiting substance blocks the protein kinase A-induced expression of cytochrome p450 17alpha-hydroxylase/C(17-20) lyase mRNA in a mouse Leydig cell line independent of cAMP responsive element binding protein phosphorylation.

Müllerian inhibiting substance (MIS) is produced by fetal Sertoli cells and causes regression of the Müllerian duct in male fetuses shortly after commitment of the bipotential embryonic gonad to testes differentiation. MIS is also produced by the Sertoli cells and granulosa cells of the adult gonads where it plays an important role in regulating steroidogenesis. We have previously shown that MIS can dramatically reduce testosterone synthesis in Leydig cells by inhibiting the expression of cytochrome P450 17alpha-hydroxylase/C(17-20) lyase (Cyp17) mRNA in vitro and in vivo.

Uterine and placental expression of steroidogenic genes during rodent pregnancy.

The ontogeny and functional role of steroidogenesis during mammalian gestation is poorly understood. This review provides a summary of our recent findings on the spatio-temporal expression of key steroidogenic genes controlling progesterone synthesis in the uterus during mouse pregnancy. We have shown that onset of cholesterol side chain cleavage cytochrome P450 (P450scc) and a newly identified isoform of murine 3beta-hydroxysteroid dehydrogenase/isomerase type VI (3betaHSD VI) expression occurs upon decidualization of the uterine wall induced by implantation.

The murine 3beta-hydroxysteroid dehydrogenase (3beta-HSD) gene family: a postulated role for 3beta-HSD VI during early pregnancy.

The enzyme 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) is essential for the biosynthesis of all active steroid hormones. The 3beta-HSD enzyme consists in multiple isoforms, each the product of a distinct gene. In the mouse, six tissue-specific isoforms have been identified.

AP-2 gamma and the homeodomain protein distal-less 3 are required for placental-specific expression of the murine 3 beta-hydroxysteroid dehydrogenase VI gene, Hsd3b6.

The enzyme 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta-HSD) is essential for the biosynthesis of all active steroid hormones. It exists as multiple isoforms in humans and rodents, each the product of a distinct gene. Human 3 beta-HSD I in placenta is essential for placental progesterone biosynthesis and thus is essential for the maintenance of pregnancy.