Expression of Caspase and BCL-2 Apoptotic Family Members in Mouse Preimplantation Embryos

Apoptosis, as determined by blastomere and DNA fragmentation, occurs in many preimplantation mouse embryos. To investigate which genes contribute to apoptosis in preimplantation embryos, we used the reverse transcription-polymerase chain reaction to assess mRNA levels for seven genes in the caspase...

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Bibliographic Details
Published in:Biology of reproduction 1999-07, Vol.61 (1), p.231-239
Main Authors: Exley, G E, Tang, C, McElhinny, A S, Warner, C M
Format: Article
Language:English
Subjects:
Ageing, cell death
Animals
Apoptosis - genetics
bcl-2-Associated X Protein
Biological and medical sciences
Blastocyst - chemistry
Caspases - genetics
Caspases - metabolism
Cell physiology
DNA Fragmentation
Embryonic Development
Female
Fluorescent Antibody Technique
Fundamental and applied biological sciences. Psychology
Gene Expression
In Situ Nick-End Labeling
Mice
Mice, Inbred C57BL
Molecular and cellular biology
Oocytes - chemistry
Pregnancy
Proto-Oncogene Proteins - analysis
Proto-Oncogene Proteins c-bcl-2 - analysis
Proto-Oncogene Proteins c-bcl-2 - genetics
RNA, Messenger - analysis
Zygote - chemistry
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Summary:Apoptosis, as determined by blastomere and DNA fragmentation, occurs in many preimplantation mouse embryos. To investigate which genes contribute to apoptosis in preimplantation embryos, we used the reverse transcription-polymerase chain reaction to assess mRNA levels for seven genes in the caspase family and seven genes in the BCL-2 family. All caspase mRNAs were detectable in oocytes, while expression in preimplantation embryos varied in a stage-specific manner. An assay for group II caspase enzymatic activity showed that although transcripts for these caspases could not be detected in zygotes, proteolytic activity could be detected in polar bodies, fragmented zygotes, and zygotes treated with staurosporine. This suggests that maternal caspases are inherited during oogenesis. Transcripts for some members of the BCL-2 family could be detected at every stage of preimplantation development. Transcripts for other members were rarely detected. When BCL-2 and BAX protein levels were assessed using immunofluorescence, both proteins were detected in zygotes and in blastocysts. When fragmented blastocysts were compared to normal blastocysts, levels of BCL-2 immunofluorescence tended to be lower in fragmented blastocysts. This result supports a model in which the ratio of BCL-2 to BAX is altered in apoptotic embryos.
ISSN:0006-3363
1529-7268
DOI:10.1095/biolreprod61.1.231