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Paternal exposure to cyclophosphamide dysregulates the gene activation program in rat preimplantation embryos
W Harrouk1, S Khatabaksh, B Robaire
1Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
Abstract:
Although there has been progress in determining the mechanisms by which maternal toxicant exposure affects progeny, there is little information on the actions of drugs administered to the father. We investigated the effects of pre-conceptional paternal exposure to cyclophosphamide, an anti-cancer agent, on embryonic gene activation in the rat. The male pronucleus was formed earlier in embryos sired by cyclophosphamide-treated male rats than in those sired by controls; early male pronucleus formation was followed by alterations in the gene activation program. BrUTP incorporation into RNA and Sp1 transcription factor immunostaining were increased and spread over both cytoplasmic and nuclear compartments in 2-cell embryos sired by cyclophosphamide-treated males compared to controls. Total RNA synthesis was constant in 1-8 cell embryos sired by drug-treated fathers, while in control embryos RNA synthesis increased four-fold to peak at the 4-cell stage. In 2-cell embryos sired by drug-treated males, the relative abundance of candidate imprinted genes was elevated significantly above control; a peak in the expression of these genes was not observed until the 8-cell stage in control embryos. Thus, paternal drug exposure temporally and spatially dysregulated rat zygotic gene activation, altering the developmental clock.
Insights
Paternal exposure to cyclophosphamide (an anti-cancer drug) altered gene activation in rat embryos. This drug exposure disrupted the embryonic developmental clock by affecting gene expression timing and patterns.
Area of Science:
- Reproductive toxicology
- Developmental biology
- Epigenetics
Background:
- Maternal toxicant exposure effects on offspring are known.
- Paternal drug exposure impacts on progeny are poorly understood.
- Investigating paternal drug effects on early embryonic development is crucial.
Purpose of the Study:
- To investigate the effects of pre-conceptional paternal exposure to cyclophosphamide on embryonic gene activation in rats.
- To understand how paternal drug exposure influences the timing and pattern of gene expression during early embryonic development.
Main Methods:
- Rats were exposed to cyclophosphamide before conception.
- Embryos from exposed and control fathers were analyzed for male pronucleus formation, RNA synthesis, and gene expression.
- Techniques included BrUTP incorporation, Sp1 transcription factor immunostaining, and analysis of candidate imprinted genes.
Main Results:
- Early male pronucleus formation observed in embryos from cyclophosphamide-treated fathers.
- Increased RNA synthesis and altered Sp1 transcription factor distribution in 2-cell embryos.
- Dysregulated temporal and spatial gene activation, including elevated abundance of imprinted genes in early embryos.
Conclusions:
- Pre-conceptional paternal exposure to cyclophosphamide dysregulates rat zygotic gene activation.
- Paternal drug exposure alters the embryonic developmental clock.
- Findings highlight the impact of paternal environmental exposures on offspring development.