Effects of aging on gene expression and mitochondrial DNA in the equine oocyte and follicle cells

Abstract

We hypothesised that advanced mare age is associated with follicle and oocyte gene alterations. The aims of the study were to examine quantitative and temporal differences in mRNA for LH receptor (LHR), amphiregulin (AREG) and epiregulin (EREG) in granulosa cells, phosphodiesterase (PDE) 4D in cumulus cells and PDE3A, G-protein-coupled receptor 3 (GPR3), growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15) and mitochondrial (mt) DNA in oocytes. Samples were collected from dominant follicles of Young (3-12 years) and Old (≥20 years) mares at 0, 6, 9 and 12h after administration of equine recombinant LH. LHR mRNA declined after 0h in Young mares, with no time effect in Old mares. For both ages, gene expression of AREG was elevated at 6 and 9h and EREG was expression was elevated at 9h, with higher expression in Old than Young mares. Cumulus cell PDE4D expression increased by 6h (Old) and 12h (Young). Oocyte GPR3 expression peaked at 9 and 12h in Young and Old mares, respectively. Expression of PDE3A increased at 6h, with the increase greater in oocytes from Old than Young mares at 6 and 9h. Mean GDF9 and BMP15 transcripts were higher in Young than Old, with a peak at 6h. Copy numbers of mtDNA did not vary over time in oocytes from Young mares, but a temporal decrease was observed in oocytes from Old mares. The results support an age-associated asynchrony in the expression of genes that are essential for follicular and oocyte maturation before ovulation.

A genome-wide association study for harness racing success in the Norwegian-Swedish coldblooded trotter reveals genes for learning and energy metabolism

“…The protein encoded by the PDE3A gene, a gene on ECA6 in which a single genome-wide significant SNP associated with career earnings is located, plays a critical role in cardiovascular function [ 89 – 91 ]. The encoded protein regulates vascular smooth muscle contraction and relaxation and has been linked to familial hypertension, cardiovascular disease, and fertility [ 89 – 92 ]. Healthy cardiovascular function is important for racing success as the act of racing undeniably requires a higher than resting-level of oxygen to support the horse’s increased muscle activity.…”

Identification of new progestogen-associated networks in mammalian ovulation using bioinformatics

“…This suggested that Pde3a was a major isoform of oocyte PDE, Pde4d was the major granulosa cell PDE isoforms and PDE10A was expressed in cumulus cells. Cell-specific expression of cAMP-PDEs in ovarian follicles has implications for understanding the hormonal regulation of folliculogenesis [ 45 ]. Further studies are needed to determine how Pde10a-Adcy1 participates in progestogenic pathways.…”

The development of in vitro embryo production in the horse

“…Overall, the main factors which appear to influence the developmental potential of equine oocytes are mare factors such as age , follicle development stage, oocyte storage and tailoring the in vitro maturation protocol to these criteria . In well‐managed clinical programmes nuclear maturation rates of 60–80% are expected .…”