Abstract: 375

INSULIN-LIKE GROWTH FACTOR-1 REGULATION OF PORCINE ENDOMETRIAL SPERMIDINE/SPERMINE N¹-ACETYLTRANSFERASE (SSAT) GENE EXPRESSION AT PERI-IMPLANTATION.

C Rodriguez-Sallaberry^{1 *}, I Kwak¹ , FJ Michel¹ , FA Simmen¹ , RCM Simmen^{1 *}
Interdisciplinary Concentration in Animal Molecular and Cell Biology, University of Florida, Gainesville, FL ¹

Insulin-like growth factor (IGF-1), highly expressed by the early pregnant pig endometrium, may act locally on this tissue to mediate the synthesis of gene products that affect periimplantation events. To evaluate a regulatory role for IGF-1 in endometrial gene expression, we used mRNA differential display to identify IGF-1 regulated genes in glandular epithelial (GE) cells from day (D) 12 pregnant endometrium. Treatment of GE cells with IGF-1 (50 ng/ml) for 12 h, and subsequent analysis of RNA resulted in the isolation of cDNA clones that were either up- or down-regulated by IGF-1 compared to control. One IGF-1 down-regulated gene was identified to be SSAT, the rate-limiting enzyme in cellular polyamine catabolism. Northern and Dot blot analysis of total RNA confirmed a reduction in SSAT mRNA levels at 3 h (P<0.1) and 12 h (P<0.05), with no difference from control levels at 24 h (P>0.5). Analysis of endometrial RNA from D10, 12, 13, 14, 19, 30 and 60 of pregnancy demonstrated high SSAT mRNA levels at D10-13, which rapidly decreased from D14 to D60. Other putative conceptus-derived proteins were tested for their ability to modulate SSAT mRNA levels in GE cells. Interferon-γ (IFN-γ), but not interleukin-1, inhibited (P<0.01) SSAT mRNA levels in GE cells after 24 h treatment. Results suggest that IGF-1 and IFN-γ may contribute to the transient expression of endometrial SSAT gene during implantation. Since SSAT regulates the availability of polyamines which are potent regulators of cell growth and apoptosis, its transient regulation by IGF-1 might be one mechanism by which, in concert with conceptus cytokines, it mediates the coordinate development of maternal endometrium and conceptuses during early pregnancy. Supported by NIH HD21961.

    This abstract is being presented on Monday, August 2 at 2:30 PM at Todd 133.