The steroidogenic acute regulatory (StAR) protein promotes intramitochondrial delivery of cholesterol to the cholesterol side-chain cleavage system, which catalyzes the first enzymatic step in all steroid synthesis. Intriguingly, substrate cholesterol derived from lipoprotein can upregulate StAR gene expression. Moreover, substrate oxysterols have been suggested to also play a role. To investig...

17alpha-Hydroxylase (CYP17) expression in propagated theca cells isolated from the ovaries of women with polycystic ovary syndrome (PCOS) is persistently elevated, compared with theca cells isolated from normal ovaries. To investigate the mechanism for increased CYP17 messenger RNA accumulation in PCOS theca cells, we examined CYP17 and steroidogenic acute regulatory protein (StAR) promoter act...

The purpose of this study was to evaluate the time-course effect of a 36-h treatment with ACTH (10 M), transforming growth factor-b1 (TGFb1; 10 M), angiotensin II (AngII; 10 M), and insulin-like growth factor I (IGF-I; 10 M) on the steroidogenic capacity of bovine adrenocortical cells (BAC) and on messenger RNA (mRNA) levels of ACTH receptor, cytochrome P450c17, 3b-hydroxysteroid dehydrogenase ...

In salmonid fishes, estradiol-17beta (E2) and 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) are the major steroid hormones controlling oocyte growth (vitellogenesis) and final maturation (resumption of meiosis). The aim of this study was to determine changes in mRNAs encoding ovarian steroidogenic enzymes and steroidogenic acute regulatory protein (StAR) during ovarian development in f...

Mitogen-activated protein kinases (MAPKs) comprise a family of serine/threonine kinases that are activated by a large variety of extracellular stimuli and play integral roles in controlling many cellular processes, from the cell surface to the nucleus. The MAPK family includes four distinct MAPK cascades, that is, extracellular signal-regulated kinase 1/2 (ERK1/2), p38 MAPK, c-Jun N-terminal ki...

DAX-1 is an unusual member of the nuclear hormone receptor superfamily whose expression is mainly, but not uniquely, restricted to steroidogenic tissues. We have recently shown that DAX-1 can block the first and rate-limiting step in steroid biosynthesis by repressing StAR (steroidogenic acute regulatory protein) expression. Here we show that DAX-1 blocks steroid production at multiple levels i...

The nuclear receptor steroidogenic factor 1 (SF-1) is essential for adrenal development and steroidogenesis. The atypical orphan nuclear receptor Dax-1 binds to SF-1 and represses SF-1 target genes. Paradoxically, however, loss-of-function mutations of Dax-1 also cause adrenal hypoplasia, suggesting that Dax-1 may function as an SF-1 coactivator under some circumstances. Indeed, we found that D...

Background: Orexin A, a small-molecule peptide, can regulate female hormones, but limited evidence for its mechanism of activity exists in ovine. Aims: The objective of this study was to investigate the effect of orexin A on progesterone (P4) secretion in cultured granulosa of sheep follicles. Methods: Sheep ovarian granulosa were isolated and ...