Granzyme G is expressed in the two-cell stage mouse embryo and is required for the maternal-zygotic transition
- Equal contributors
1 Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
2 Department of Physiology, National Cheng Kung University, Tainan 701, Taiwan
3 Department of Animal Science and Biotechnology, Tunghai University, Taichung 407, Taiwan
4 Division of Infertility Clinic, Lee Women's Hospital, and Chung Shan Medical University, Taichung 406, Taiwan
5 Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan 333, Taiwan
BMC Developmental Biology 2010, 10:88 doi:10.1186/1471-213X-10-88Published: 12 August 2010
Detailed knowledge of the molecular and cellular mechanisms that direct spatial and temporal gene expression in pre-implantation embryos is critical for understanding the control of the maternal-zygotic transition and cell differentiation in early embryonic development. In this study, twenty-three clones, expressed at different stages of early mouse development, were identified using differential display reverse transcription polymerase chain reaction (DDRT-PCR). One of these clones, which is expressed in 2-cell stage embryos at 48 hr post-hCG injection, shows a perfect sequence homology to the gene encoding the granzyme G protein. The granzyme family members are serine proteases that are present in the secretory granules of cytolytic T lymphocytes. However, the pattern of granzyme G expression and its function in early mouse embryos are entirely unknown.
Upon the introduction of an antisense morpholino (2 mM) against granzyme G to knock-down endogenous gene function, all embryos were arrested at the 2- to 4-cell stages of egg cleavage, and the de novo synthesis of zygotic RNAs was decreased. The embryonic survival rate was dramatically decreased at the late 2-cell stage when serine protease-specific inhibitors, 0.1 mM 3,4-dichloroisocoumarin (3,4-DCI), and 2 mM phenyl methanesulphonyl fluoride (PMSF), were added to the in vitro embryonic culture medium. Survival was not affected by the addition of 0.5 mM EDTA, a metalloproteinase inhibitor.
We characterized for the first time the expression and function of granzyme G during early stage embryogenesis. Our data suggest that granzyme G is an important factor in early mouse embryonic development and may play a novel role in the elimination of maternal proteins and the triggering of zygotic gene expression during the maternal-zygotic transition.