Document Type : Original Article
Department of Biology, Faculty of Science, Science and Research Branch Islamic Azad University, Tehran, Iran;Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, T
Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
Department of Embryology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
4Department of Endocrinology and Female Infertility, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
The diminished ovarian reserve (DOR) is a condition characterized by a reduction in the number and/or quality of oocytes. This primary infertility disorder is usually accompanied with an increase in the follicle-stimulating hormone (FSH) levels and regular menses. Although there are many factors contributing to the DOR situation, it is likely that many of idiopathic cases have genetic/epigenetic bases. The association between the FMR1 premutation (50-200 CGG repeats) and the premature ovarian failure (POF) suggests that epigenetic disorders of FMR1 can act as a risk factor for the DOR as well. The aim of this study was to analyze the mRNA expression and epigenetic alteration (histone acetylation/methylation) of the FMR1 gene in blood and granulosa cells of 20 infertile women.
Materials and Methods
In this case-control study, we analyzed the mRNA expression and epigenetic altration of the FMR1 gene in blood and granulosa cells of 20 infertile women. These women were referred to the Royan Institute, having been clinically diagnosed as DOR patients. Our control group consisted of 20 women with normal antral follicle numbers and serum FSH level. All these women had normal karyotype and no history of genetic disorders. The number of CGG triplet repeats in the exon 1 of the FMR1 gene was analyzed in all samples.
Results clearly demonstrated significantly higher expression of the FMR1 gene in blood and granulosa cells of the DOR patients with the FMR1 premutation compared to the control group. In addition, epigenetic marks of histone 3 lysine 9 acetylation (H3K9ac) and di-metylation (H3K9me2) showed significantly higher incorporations in the regulatory regions of the FMR1 gene, including the promoter and the exon 1, whereas tri-metylation (H3K9me3) mark showed no significant difference between two groups.
Our data demonstrates, for the first time, the dynamicity of gene expression and histone modification pattern in regulation of FMR1 gene, and implies the key role played by epigenetics in the development of the ovarian function.