PARENT SESSION
SLIDE SESSION 12: IMPLANTATION & EARLY DEVELOPMENT
Chairs: Richard Leach, Carol Brenner, Jeff Reese (Trainee)
Univ Ottawa-Monpetit 202
1:30 PM-3:30 PM

ISOLATION OF A NOVEL GENE EXPRESSED IN THE RAT ENDOMETRIUM AT THE TIME OF MAXIMAL SENSITIZATION FOR THE DECIDUAL CELL REACTION.

Simmons, David¹, Kennedy, Thomas¹, ¹

ABSTRACT- Endometrial receptivity for implantation and sensitization for decidualization in rodents is a transient state under the control of the ovarian steroid hormones progesterone and estrogen. Although its precise timing, length and regulation has been characterized in detail, it remains unclear what molecular events mediate the onset of uterine receptivity. Suppressive subtraction hybridization (SSH) was used in an attempt to isolate genes differentially expressed in uteri maximally sensitized for the decidual cell reaction and potentially involved in uterine receptivity. Briefly, ovariectomized rats were treated with estradiol and progesterone to differentially sensitize their uteri for decidualization. mRNA from maximally sensitized uteri (equivalent of day 5 of pseudopregnancy) and temporally non-sensitized uteri (equivalent of day 4 of pseudopregnancy) was used in the SSH to identify genes expressed specifically in the day 5, maximally sensitized uteri. Herein we describe the isolation of a novel gene, termed C2, with expression restricted to the day 5, maximally sensitized uteri. After isolating the gene fragment, both 5' and 3' RACE was performed in order to obtain a full-length nucleotide sequence. Results of a database search revealed no significant homology of C2 to any know genes. Northern blot analysis indicated at least a 15 fold increase in C2 mRNA expression that was restricted to the day 5 endometrium and its expression was down-regulated by day 6, both in the presence and absence of decidualization. In situ hybridization experiments showed that C2 mRNA up-regulation on day 5 of pseudopregnancy occurred within the glandular epithelium. C2 mRNA showed limited tissue distribution and was detected at low levels in the brain, kidney, cervix, vagina, oviduct, and ovary by northern blot analysis. Considering the tight restriction of expression of C2, it is a good candidate as a new marker of the window of receptivity for implantation in the rat.

KEY WORDS: uterine receptivity, implantation, endometrium, suppressive subtraction hybridization