Expression data from progesterone receptor knockout versus heterozygous mouse oviducts

The oviducts play a critical role in gamete and embryo transport, as well as supporting fertilization and early embryo development. Progesterone receptor (PGR) is a transcription factor highly expressed in oviductal cells, while it’s activating ligand, progesterone (P4), surges to peak levels as ovulation approaches. P4 is known to regulate oviduct cilia beating and muscular contractions in vitro, but how PGR may mediate this in vivo is poorly understood. We used PGR-knockout (PRKO) mice to determine how PGR regulates oviductal function during the periovulatory period, in particular oviductal transport and embryo support. We used microarrays to identify putative PGR-regulated genes in the oviduct during the periovulatory period, a time when the oviduct is preparing to receive the newly-ovulated COC. The mutant strain used in this experiment were PRlacZ knock-in mice which originated from Assoc Prof John Lydon, Baylor College of Medicine, Houston TX, USA. The lacZ insertion results in disruption of transcription of both isoforms of PGR (Ismail et al, 2002, Mol Endocrinol 16:2475-2489), and therefore mice homozygous for the lacZ insertion are a phenocopy of the knockout strain described by Lydon et al. (1995, Genes Dev. 9:2266-2278) and are hereafter referred to as PRKO. Heterozygous mice (PR+/-) are a phenocopy of WT and have normal fertility (Ismail et al, 2002) and are therefore appropriate controls. Whole oviducts were collected from pre-pubertal PRKO and PR+/- mice 8 h after a standard protocol for hormonal induction of ovulation. Day 21-23 old mice were injected i.p. with 5IU of equine chorionic gonadotropin (eCG) to stimulate follicle growth, followed 44-47 h later by i.p. injection of 5 IU of human chorionic gonadotropin (hCG) to trigger ovulatory processes. Oviducts from 15 animals were collected per genotype, with oviducts from 3 animals pooled per sample for a total of n = 5 samples per genotype.