Embryo

TRAIL and KILLER Are Expressed and Induce Apoptosis in the Murine Preimplantation Embryo

Abstract
TRAIL and KILLER are a death-inducing ligand and receptor pair that belong to the TNF and TNF receptor superfamilies respectively. To date only one apoptosis-inducing TRAIL receptor (murine KILLER, MK) has been identified in mice and it is a homolog of human Death Receptor 5 (DR5). While the expression of other death receptors such as Fas and TNFR1 have been documented in mammalian preimplantation embryos, currently there is no evidence demonstrating either the presence or function of TRAIL and its corresponding death receptor MK. We found using RT-PCR and confocal immunofluorescent microscopy that both TRAIL and MK are expressed from the 1-cell through the blastocyst stage of murine preimplantation embryo development. These proteins are expressed mainly at the cell surface from the 1-cell through the morula stage. At a blastocyst stage, both TRAIL and MK exhibit an apical staining pattern in the trophectoderm cells. Finally, using the TUNEL assay we demonstrated that MK induces apoptosis in blastocysts sensitized to TRAIL via actinomycin D. Taken together these data are the first to demonstrate the presence and function of TRAIL and MK, a death-inducing ligand and its receptor, in mammalian preimplantation embryos.

Key words: Embryo • Immunology • Apoptosis • Cytokines • Early development

This article has been cited by other articles:

				C. Rieger, R. Poppino, R. Sheridan, K. Moley, R. Mitra, and D. Gottlieb Polony analysis of gene expression in ES cells and blastocysts Nucleic Acids Res., December 10, 2007; (2007) gkm1076v1. [Abstract] [Full Text] [PDF]