The molecular signature of cumulus cells is compromised in infertile women of advanced maternal age

Abstract

It is well known that women in their forties experience a decline in their fertility. Compromised folliculogenesis leading to poor oocyte quality contributes to a reduction in implantation potential. This study investigated the molecular signature of cumulus cells from infertile women in their early-mid forties relative to young fertile oocyte donors. Research study Patients donated with consent cumulus cells during routine IVF treatment: Group A = young fertile oocyte donors (n = 20) and Group B = infertile normal responders with normal ovarian reserve in their early-mid forties (n = 28). Proteomic analysis of pooled cumulus cells involved liquid chromatography tandem mass spectrometry (LC-MS) and Western blotting. Cumulus cell gene expression analysis was performed by quantitative real-time PCR relative to a constant housekeeping gene. LC-MS identified 1423 proteins across these cumulus cell samples. Statistical analysis revealed 64 proteins with increased expression in Group B, including proteins involved in fatty acid metabolism e.g., ACAT2 and HSD17B4 (P<0.05; >1.5 fold change). In addition, 48 proteins showed decreased expression in Group B, including pre-mRNA splicing factors e.g., KHSRP, SFPQ and DDX46 (P<0.05; >1.5 fold change). Western blotting successfully validated the LC-MS data confirming differential expression of ACAT2, KHSRP, SFPQ and DDX46. Cumulus cell gene expression of ACAT2, HSD17B4, ACSL3, CPT2, SCD and FASN further confirmed the up-regulation of fatty acid metabolism genes relative to infertility and maternal aging (P<0.05). In a novel approach, this study examined protein and gene expression of cumulus cells with respect to infertility and maternal age. A compromised molecular environment was observed with a deficiency in pre-mRNA splicing factors and increased fatty acid metabolism in infertile aged cumulus cells. Investigation of these pathways may contribute to improvements in patient care and success for infertile women in their forties.