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

THE ROLE OF GLUCOSE-6-PHOSPHATE ISOMERASE IN EMBRYO IMPLANTATION IN THE FERRET (M. putorius).

Clamon, Laura¹, Bahr, Janice¹, ¹

ABSTRACT- In contrast to rodent models of embryo implantation, ferret (Mustela putorius) implantation cannot be terminated by administration of estrogen. Instead, a protein extracted from corpora lutea (CL) on pregnancy or pseudopregnancy days 6-9 has been shown to trigger implantation in ovariectomized (ovx), progesterone(P4)-treated mink and ferrets. Previously, an unidentified, basic 60 kilodalton (kD) protein was isolated from ferret corpora lutea (CL) on days 6-9 of pseudopregnancy. Injection of this protein triggered implantation in an ovx ferret. The aim of our research was to identify and characterize this ferret luteal implantation protein. Ovaries were removed from ferrets on day 8 of pseudopregnancy and CL were processed for chromatography. A 60 kDA, basic protein was isolated from the homogenate by chromatofocusing. Two fragments of the protein were sequenced and displayed 100% homology to pig glucose-6-phosphate-isomerase (GPI). GPI is a glycolytic enzyme also known to function as a neural growth factor (neuroleukin) and tumor motility factor (AMF). A 750 base-pair region of ferret GPI cDNA was amplified by PCR and sequenced, revealing 90% similarity to both pig and rabbit GPI. Plasma levels of GPI, as determined by enzymatic activity, were found to be significantly elevated on days 6 and 9, the time at which CL homogenates had been found effective in inducing implantation. To test whether GPI triggers implantation, 7 mated, ovx ferrets were treated with P4 and rabbit GPI from days 6-9 of pregnancy. Intact, mated ferrets served as positive controls and mated, ovx, P4 and saline-treated ferrets served as negative controls. Implantation occurred in all positive controls, 3 of 7 GPI-treated ferrets and none of the negative controls. Next, a chicken antibody to ferret GPI was produced for future passive immunization of pregnant ferrets. We conclude that GPI plays a crucial role in embryo implantation in the domestic ferret. It is expressed during the critical pre-implantation period, and can trigger embryonic invasion of the maternal epithelium. This action represents a novel function of GPI, which may be related to its role in tumor cell motility. In addition, the role of GPI in implantation may be pivotal in the regulation of delayed implantation in mustelids. Supported by U of I Research Board and NIH PHS2T32HD07028.

KEY WORDS: delayed implantation, glucose-6-phosphate isomerase (GPI) (AMF)(neuroleukin), ferret ( Mustela putorius furo)