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Published on: January 17, 2016
Eya1 and Eya2 gene expression is down-regulated during somitic myogenesis in the cadmium-induced omphalocele chick
Takashi Doi1, Prem Puri, John Bannigan
1National Children's Research Centre, Our Lady's Children's Hospital, Dublin 12, Ireland.
Purpose:
The molecular mechanisms underlying omphalocele are still largely unknown. Recently, established cadmium (Cd)-induced omphalocele chick model has been used to investigate the pathogenesis of omphalocele. The earliest histologic changes in this model has been observed in somites 4 hours posttreatment, leading us to hypothesize that disruption of migration of somite-derived cells ventrally may cause omphalocele phenotype. Eyes absent (Eya) genes are expressed in the somite (dermomyotome) and play a key role in somitic myogenesis. We designed this study to investigate the hypothesis that Eya1 and Eya2 gene expression is down-regulated during the critical period of early embryogenesis in the Cd-induced omphalocele chick model.
Methods:
After 60 hours of incubation, chicks were exposed to either chick saline or Cd and divided into control and Cd (n = 24 for each group). Chicks were then harvested 1 hour, 4 hours, and 8 hours posttreatment. Real-time quantitative polymerase chain reaction was performed to evaluate gene expression levels of Eya1 and Eya2 in the chick embryo, and they were statistically analyzed. Immunofluorescence confocal microscopy was also performed to evaluate protein expression and distribution pattern of Eya1 and Eya2.
Results:
At 4 hours posttreatment, the relative messenger RNA expression levels of Eya1 and Eya2 were significantly down-regulated in the Cd group compared with controls (P < .05). The intensity of Eya1 and Eya2 immunofluorescence was also markedly diminished at 4 hours in the Cd-treated embryos, whereas in control embryos, strong intensity of immunofluorescence of them was expressed in the dermomyotomal cells.
Conclusion:
Down-regulation of Eya genes during the critical period of early embryogenesis may contribute to omphalocele phenotype in the Cd chick model, interfering with migration of embryonic body wall ventrally.
Insights
Cadmium exposure down-regulates Eya1 and Eya2 gene expression in chick embryos, potentially causing omphalocele by disrupting cell migration. This finding sheds light on omphalocele pathogenesis in a developmental model.
Area of Science:
- Developmental biology
- Teratology
- Molecular genetics
Background:
- Omphalocele pathogenesis remains largely unknown.
- A cadmium (Cd)-induced chick model reveals early somite changes, suggesting disrupted ventral cell migration.
- Eyes absent (Eya) genes are crucial for somite development and myogenesis.
Purpose of the Study:
- To investigate the hypothesis that Eya1 and Eya2 gene expression is reduced during early embryogenesis in the Cd-induced omphalocele chick model.
- To explore the role of Eya genes in Cd-induced omphalocele.
Main Methods:
- Chick embryos were exposed to Cd or saline and harvested at 1, 4, and 8 hours posttreatment.
- Real-time quantitative polymerase chain reaction assessed Eya1 and Eya2 messenger RNA levels.
- Immunofluorescence confocal microscopy evaluated Eya1 and Eya2 protein expression and distribution.
Main Results:
- Eya1 and Eya2 messenger RNA levels were significantly down-regulated at 4 hours post-Cd exposure (P < .05).
- Eya1 and Eya2 protein immunofluorescence intensity was markedly diminished in Cd-treated embryos at 4 hours.
- Control embryos showed strong Eya1 and Eya2 expression in dermomyotomal cells.
Conclusions:
- Down-regulation of Eya genes during critical embryogenesis may contribute to omphalocele phenotype in the Cd chick model.
- Interference with embryonic ventral body wall migration is a potential consequence of Eya gene down-regulation.
- This study provides insights into the molecular mechanisms of Cd-induced omphalocele.
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