Effect of murine GM-CSF on the expression of GLUT isoforms during mouse preimplantation embryo development

Abstract

Objective: Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been known to promote glucose uptake in murine preimplantation embryo. However, the role of the facilitated glucose transporter (GLUT) isoforms on GM-CSF-stimulated glucose uptake during murine preimplantation development has not been examined. The aim of this study was to investigate the role of GLUT isoforms in GM-CSF stimulated mouse preimplantation embryos in vitro. Design: We examined the effect of GM-CSF on the mouse embryo development and determined the expression of the GLUT isoforms in the mouse blastocysts using semiquantitative RT-PCR. Materials/Methods: Mouse 2-cell embryos were collected from the oviducts of 6-week-old ICR mice at 48 hours after hCG injection. Embryos were cultured in P-1 medium supplemented with mouse GM-CSF (0, 1, 5 and 10 ng/ml) for 3 days. Total RNA was isolated from 50 blastocysts and was reverse transcribed into cDNA and amplified by PCR using specific primers for beta-actin, GLUT 1, 2, 3, and 8 target genes between the GM-CSF supplemented groups and control group. Results: The percentage of blastocyst formation correlated with the GM-CSF concentrations (65.5% for control and 68.6%, 73.0%, 76.1% for 1, 5 and 10 ng/ml, respectively). The mean cell number in a blastocyst was significantly higher in the GM-CSF supplemented groups (95.1 ± 20.8, 91.6 ± 12.4, and 92.0 ± 12.4 for 1, 5, and 10 ng/ml, respectively) compared to the control group (67.9. ± 17.1). GLUT 1, 3, and 8 were detected from mouse blastocysts in both the GM-CSF supplemented groups and the control group. Unlike GLUT 1, 3, and 8, GLUT 2 was not expressed in any groups. And there was no significant difference in the expression of GLUT 1, 3, and 8 between in the GM-CSF supplemented groups and the control group. Conclusions: The results of this study suggest that GLUT isoforms may not be responsible for GM-CSF stimulated glucose uptake in mouse preimplantaion embryo. Thus, the further investigation is necessary to identify the mechanism of GM-CSF-stimulated glucose uptake during mouse preimplantation development.