The effect of progesterone replacement on gene expression in the corpus luteum during induced regression and late luteal phase in the bonnet monkey (Macaca radiata)

Genome-wide differences in DNA methylation changes in caprine ovaries between oestrous and dioestrous phases

Background

DNA methylation plays a vital role in reproduction. Entire genome DNA methylation changes during the oestrous phase (ES) and dioestrous phase (DS) in the ovaries of Guanzhong dairy goats were investigated using bisulphite sequencing to understand the molecular biological mechanisms of these goats’ oestrous cycle.

Results

We discovered distinct genome-wide DNA methylation patterns in ES and DS ovaries. A total of 26,910 differentially methylated regions were upregulated and 21,453 differentially methylated regions were downregulated in the ES samples compared with the DS samples (P-values ≤0.05 and fold change of methylation ratios ≥2). Differentially methylated region analysis showed hypomethylation in the gene body regions and hypermethylation in the joining region between upstream regions and gene bodies. The methylation ratios of the STAR, FGF2, FGF12, BMP5 and SMAD6 genes in the ES samples were lower than those of the DS samples (P-values ≤0.05 and fold change of methylation ratios ≥2). Conversely, the methylation ratios of the EGFR, TGFBR2, IGF2BP1 and MMD2 genes increased in the ES samples compared with the DS samples. In addition, 223 differentially methylated genes were found in the GnRH signalling pathway (KO04912), ovarian steroidogenesis pathway (KO04913), oestrogen signalling pathway (KO04915), oxytocin signalling pathway (KO04921), insulin secretion pathway (KO04911) and MAPK signalling pathway (KO04010).

Conclusions

This study is the first large-scale comparison of the high-resolution DNA methylation landscapes of oestrous and dioestrous ovaries from dairy goats. Previous studies and our investigations have shown that the NR5A2, STAR, FGF2 and BMP5 genes might have potential application value in regulating caprine oestrus.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0301-x) contains supplementary material, which is available to authorized users.

Effects of steroid ablation and progestin replacement on the transcriptome of the primate corpus luteum during simulated early pregnancy

Previous microarray analyses indicated that a portion of the transcriptome in the macaque corpus luteum (CL) of the menstrual cycle was regulated indirectly by luteinizing hormone via the local actions of steroid hormones, notably progesterone (P). The current study was designed to investigate this concept in the CL of early pregnancy by analyzing chorionic gonadotrophin (CG)-regulated genes that are dependent versus independent of local steroid action. Exogenous human chorionic gonadotropin treatment simulating early pregnancy (SEP) began on Day 9 of the luteal phase in female rhesus monkeys with and without concurrent administration of the 3-β-hydroxysteroid dehydrogenase inhibitor trilostane (TRL) with or without the synthetic progestin R5020. Compared with SEP treatment alone, TRL altered 50 mRNA transcripts on Day 10, rising to 95 on Day 15 (P<0.05, ≥2-fold change in gene expression). Steroid-sensitive genes were validated; notably effects of steroid ablation and P replacement varied by day. Expression of some genes previously identified as P-regulated in the macaque CL during the menstrual cycle were not significantly altered by steroid ablation and P replacement during CG exposure in SEP. These data indicate that the majority of CG-regulated luteal transcripts are differentially expressed independently of local steroid actions. However, the steroid-regulated genes in the macaque CL may be essential during early pregnancy, based on previous reports that TRL treatment initiates premature structural regression of the CL during SEP. These data reinforce the concept that the structure, function and regulation of the rescued CL in early pregnancy differs from the CL of the menstrual cycle in primates.

Luteinizing hormone regulates inhibin-α subunit expression through multiple signaling pathways involving steroidogenic factor-1 and beta-catenin in the macaque corpus luteum

We employed different experimental model systems to define the role of GATA4, beta-catenin, and steroidogenic factor (SF-1) transcriptional factors in the regulation of monkey luteal inhibin secretion. Reverse transcription polymerase chain reactions and western blotting analyses show high expression of inhibin-α, GATA4, and beta-catenin in corpus luteum (CL) of the mid-luteal phase. Gonadotropin-releasing hormone receptor antagonist-induced luteolysis model suggested the significance of luteinizing hormone (LH) in regulating these transcriptional factors. Inducible cyclic AMP early repressor mRNA expression was detected in the CL and no change was observed in different stages of CL. Following amino acid sequence analysis, interaction between SF-1 and beta-catenin in mid-stage CL was verified by reciprocal co-immunoprecipitation experiments coupled to immunoblot analysis. Electrophoretic mobility shift analysis support the role of SF-1 in regulating luteal inhibin-α expression. Our results suggest a possible multiple crosstalk of Wnt, cAMP, and SF-1 in the regulation of luteal inhibin secretion.

Microarray analysis of the primate luteal transcriptome during chorionic gonadotrophin administration simulating early pregnancy

To explore chorionic gonadotrophin (CG)-regulated gene expression in the primate corpus luteum (CL), adult female rhesus macaques were treated in a model of simulated early pregnancy (SEP). Total RNA was isolated from individual CL after specific intervals of exposure (1, 3, 6 and 9 days) to recombinant hCG in vivo and hybridized to Affymetrix™ GeneChip Rhesus Macaque Genome Arrays. The mRNA levels of 1192 transcripts changed ≥2-fold [one-way ANOVA, false discovery rate (FDR) correction; P< 0.05] during SEP when compared with Day 10 untreated controls. Real-time PCR validation indicated that 15 of 17 genes matched in expression pattern between PCR and microarray. Protein levels of three genes identified as CG-sensitive, CYP19A1 (aromatase), PGRMC1 (progestin-binding protein) and STAR (steroidogenic acute regulatory protein) were quantified by western blot analysis. To further analyze global changes in gene expression induced by CG exposure, luteal gene expression was compared between SEP (rescued) and regressing CL, utilizing previously banked GeneChip data from the luteal phase of the menstrual cycle. Expression patterns and mRNA levels were analyzed between time-matched intervals. Transcripts for 7677 mRNAs differed in expression patterns ≥2-fold (one-way ANOVA, FDR correction; P< 0.05) between the hCG-exposed (SEP) CL and regressing CL. Regressed CL (at menses) were most unlike all other CL. Pathway analysis of significantly affected transcripts was performed; the pathway most impacted by CG exposure was steroid biosynthesis. Further comparisons of the genome-wide changes in luteal gene expression during CG rescue and luteolysis in the natural menstrual cycle should identify additional key regulatory pathways promoting primate fertility.