Impact of the LH surge on granulosa cell transcript levels as markers of oocyte developmental competence in cattle

Abstract

In the case of in vitro embryonic production, it is known that not all oocytes detain the developmental capacity to form an embryo. This capacity appears to be acquired through completion of folliculogenesis, during which the oocyte and follicular cells influence their respective destinies. The differentiation status of granulosa cells (GCs) could therefore offer an indicator of oocyte quality. The aim of this study was to compare mRNA transcript abundance in GCs associated with oocytes that subsequently reach or not the blastocyst stage. GCs were collected from cattle following an ovarian stimulation protocol that did or did not include the administration of LH. GCs were classified according to the developmental stage achieved by the associated oocytes. Transcript abundance was measured by microarray. Follicles (nZ189) obtained from cows before and after the LH surge were essentially similar and the rates of oocytes reaching the blastocyst stage were not significantly different (52 vs 41%), but blastocyst quality was significantly better in the post-LH-surge group. In GCs from the pre-LH-surge group and associated with developmentally competent oocytes, 18 overexpressed and 22 underexpressed transcripts were found, including novel uncharacterized transcripts, whereas no differentially expressed transcripts were associated with developmentally different oocytes in the post-LH-surge group. The novel transcriptomic response associated with LH appeared to mask the difference. Based on oocyte developmental competence, the period prior to the LH surge appears best suited for studying competence-associated mRNA transcripts in bovine follicle cells.

Differential gene expression of granulosa cells after ovarian superstimulation in beef cattle

“…However, results of this study suggest that the multiple pre-ovulatory follicles that develop after superstimulation are not typical dominant follicles. The list of upregulated genes in the superstimulation group in this study is similar to those of other studies (Gilbert et al 2011(Gilbert et al , 2012 from dominant follicles before the LH surge at day 14 of the estrous cycle. It is important to note that the granulosa cells from our superstimulation group were collected 24 h after exogenous LH surge (i.e.…”

“…In this study, some upregulated genes in the matrix-remodeling network (HPSE, early growth response 1 (EGR1), tissue inhibitor metalloproteinase 1 (TIMP1), and plasminogen activator (PLAT)) are markers of the initiation of ovulatory process (Gilbert et al 2011(Gilbert et al , 2012. HPSE encodes heparanase that cleaves heparan sulfate (one of the tissue glycosaminoglycans) during matrix remodeling and is highly expressed in bovine granulosa cells 12 h after GNRH treatment.…”

“…Further, expression of three other genes involved in matrix remodeling, SERPINE, FN1, and IGF2 was also elevated in the superstimulation group. SERPINE is downregulated in bovine granulosa cells after LH treatment (Gilbert et al 2012) and FN1 expression is reported to be inversely related to follicle maturation (Colman-Lerner et al 1999, Yasuda et al 2005, Berkholtz et al 2006b). IGF proteins are produced by the granulosa cells and have been shown to have a synergetic effect with FSH to induce cellular growth and proliferation (Hammond et al 1985).…”

Granulosa cell function and oocyte competence: Super-follicles, super-moms and super-stimulation in cattle

“…The superstimulation protocol used in this study included exogenous administration of FSH over 4 days after follicular wave synchronization and LH 24 h after progesterone-device removal. Therefore, previously documented biomarker genes of early-and late-LH response (those related to vascularization, lipid synthesis, protein localization and intracellular transport) were expected to be already upregulated (Gilbert et al, 2011(Gilbert et al, , 2012Barros et al, 2012). The transcriptomic profile of granulosa cells after superstimulation, however, displayed up-regulation of only a few markers of the LH surge compared to granulosa cells from natural dominant follicles; differentially expressed genes were related to matrix remodeling (i.e., tissue proliferation), disturbance of angiogenesis, apoptosis, and oxidative stress response (Fig.…”

A Genetical Genomics Methodology to Identify Genetic Markers of a Bovine Fertility Phenotype Based on CYP19A1 Gene Expression

“…22 The coagulation pathway seems to be important in competent follicles according to this study and recent publications from mouse studies 23 and our group have further identified SERPINE1 (Serpin peptidase inhibitor, clade E (nexin, plasminogen activator inhibitor type 1), member 1), SERPINA5 (serpin peptidase inhibitor, clade A [alpha-1 antiproteinase, antitrypsin], member 5), F3 (coagulation factor III (thromboplastin, tissue factor), A2M (alpha-2-macroglobulin), PLAUR (plasminogen activator, urokinase receptor), and F2R (coagulation factor II [thrombin] receptor) as a determinant of oocyte quality. 24,25 Gene selection. In this study, genes with high fold change values, interesting positions in pathways, and good genetic opportunities (availabilities of SNPs and their MAFs) were selected.…”