Gene expression profiling of bovine preovulatory follicles: gonadotropin surge and prostanoid-dependent up-regulation of genes potentially linked to the ovulatory process

Abstract

The molecular mechanisms of ovulation and luteinization have not been well established, partially due to lack of a comprehensive understanding of functionally significant genes up-regulated in response to an ovulatory stimulus and the signaling pathways involved. In the present study, transcripts increased in bovine preovulatory follicles following a GnRH-induced LH surge were identified using microarray technology. Increased expression of 368 and 878 genes was detected at 12 (368 genes) and 20 h (878 genes) following GnRH injection. The temporal, cell specific and prostanoid-dependent regulation of selected genes (ADAM10,DBI,CD36,MTSS1,TFG, andRABGAP1) identified from microarray studies and related genes (ADAM17andAREG) of potential significance were also investigated. Expression of mRNA forDBIandCD36was simultaneously up-regulated in theca and granulosa cells (GC) following the LH surge, whereas temporal regulation ofADAM10,MTSS1,TFG, andRABGAP1was distinct in the two cell compartments and increased granulosaTFGandRABGAP1mRNA were prostanoid dependent.AREGmRNA was increased in theca and GCs at 12 and 24 h following GnRH injection.ADAM17mRNA was increased in theca, but reduced in GCs 24 h following GnRH injection. The increasedADAM17andAREGmRNA were prostanoid dependent. ADAM10 and ADAM17 protein were increased specifically in the apex but not the base of preovulatory follicles and the increase in ADAM17 was prostanoid dependent. Results reveal novel information on the regulation of preovulatory gene expression and suggest a potential functional role for ADAM10 and ADAM17 proteins in the region of follicle rupture.