Hypomethylation of specific CpG sites in the promoter region of steroidogeneic genes (GATA6 and StAR) in prenatally androgenized rats.

INTRODUCTION: The methylation level of promoters is one of the most studied and well-known epigenetic mechanisms that programs the amount of gene expression. Over expression of steroidogenesis genes via epigenetic control can result in hypetandrogenism, which is the main endocrine aspect of polycystic ovarian syndrome (PCOS).

AIMS: In the present study we aimed to determine and compare the promoter methylation levels of three steroidogenic genes, CYP17, GATA6 and StAR, in theca cells of prenatally androgenized (PNA) rats to those of controls.

MATERIALS AND METHODS: Pregnant Wistar rats in the PNA group received 5 mg free testosterone, dissolved in 500 ml solvent, subcutaneously injected on day 20 of pregnancy, while controls were injected with 500 ml of solvent only. Theca cell samples, taken from the ovaries of eight to ten female offspring of both the PNA and control groups, were measured for promoter methylation levels of the aforementioned genes, using the bisulfite sequence PCR (BSP) method.

KEY FINDINGS: Although the promoters of all three genes were slightly hypomethylated in the PNA group, the differences observed were not significant compared to the control group. The methylation of -520 and -822 positions, in the GATA6 and the StAR promoter respectively, were significantly decreased in the PNA group.

SIGNIFICANCES: The results of this study suggest that alterations in the steroidogenesis pathway after exposure to excess androgen may be a result of changes in the pattern of the methylation of the relevant genes.