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(541) AKT IS EXPRESSED AND PREVENTS APOPTOSIS IN THE MURINE PREIMPLANTATION EMBRYO. Riley, Joan1, Carayannopoulos, Mary1, 2, Wyman, Amanda1, Schlein, Amanda1, Moley, Kelle1, 1 Washington University School of Medicine, St. Louis, MO2 Washington University School of Medicine, St. Louis, MO ABSTRACT- Akt, a serine-threonine kinase, plays an important role in controlling the balance between cell survival and cell death. Akt is activated following growth factor or insulin stimulation of PI3K. To date there is no evidence demonstrating either the presence or function of Akt in murine preimplantation embryos. We found using confocal immunofluorescent microscopy that Akt is expressed from the 1-cell through the blastocyst stage of embryo development. This protein is localized mainly at the plasma membrane from the 1-cell through the morula stage. At a blastocyst stage, Akt exhibits an apical staining pattern in the trophectoderm cells with cytoplasmic staining throughout the remaining embryo. In addition, Akt is active during preimplantation development as it is constitutively phosphorylated on serine residue 473. We have also detected Akt expression in both ES and TS cell lines via western blot analysis. Similar to what was found in the blastocysts Akt was constitutively active in the TS cell lines. Using the TUNEL assay we demonstrated that blastocysts cultured in the presence of an Akt inhibitor displayed increased levels of apoptosis as compared to controls. Moreover preliminary data suggests the increase in apoptosis correlates with a decrease in cell surface expression of the facilitative glucose transporter GLUT-1. Thus Akt activation may in part prevent apoptosis in blastocysts by maintaining GLUT-1 at the cell surface. Taken together these data are the first to demonstrate the presence and function of Akt in murine preimplantation embryos. KEY WORDS: preimplantation embryo, Akt, apoptosis |
