Thermal Adaptation Inhibits the Wnt Signaling Pathway Regulating Autophagy and Improving the Development of Embryos

Area of Science:

• Reproductive biology
• Developmental biology
• Cellular stress response

Background:

• Heat stress negatively impacts reproductive capacity and embryo development.
• Thermal adaptation strategies may offer protective benefits against heat-induced damage.
• Understanding the molecular mechanisms of thermal adaptation is crucial for improving assisted reproductive technologies.

Purpose of the Study:

• To elucidate the molecular mechanisms by which a specific thermal adaptation protocol enhances the quality of in vitro cultured mouse morula-stage embryos.
• To investigate the impact of thermal adaptation on key gene and protein expression related to embryo development and quality.
• To determine the role of Wnt signaling and autophagy pathways in mediating the beneficial effects of thermal adaptation.

Main Methods:

• Mouse morula-stage embryos were subjected to a thermal adaptation protocol (39°C for 1 hour, followed by recovery at 37°C for 3 hours).
• Quantitative gene expression analysis (RT-qPCR) was performed for selected genes, including Cdh1, Gja1, Dnmt1, Wnt, mTOR, GSK3β, LC3B, and Beclin-1.
• Protein expression levels for Wnt and autophagy markers were assessed.
• Embryo quality was evaluated by assessing the blastocyst rate and morphological integrity.

Main Results:

• Thermal adaptation significantly increased the expression of embryo quality-associated genes (Cdh1, Gja1, Dnmt1).
• A decrease in Wnt and mTOR gene and protein expression was observed following thermal adaptation.
• Upregulation of GSK3β and autophagy-related markers (LC3B, Beclin-1) was evident after thermal adaptation.
• The blastocyst rate and overall embryo quality were significantly improved in the thermally adapted group.

Conclusions:

• Thermal adaptation enhances the developmental competence of early mouse embryos.
• The beneficial effects are mediated by the inhibition of the Wnt signaling pathway and the activation of autophagy.
• This study provides insights into optimizing in vitro embryo culture conditions for improved reproductive outcomes.