Dax1 associates with Esrrb and regulates its function in embryonic stem cells

Area of Science:

• Stem cell biology
• Molecular endocrinology
• Transcriptional regulation

Background:

• Embryonic stem (ES) cells possess self-renewal and pluripotency, governed by the Oct3/4 transcriptional network.
• Nuclear hormone receptor Dax1 is integral to this network.
• Identifying novel interactions is crucial for understanding ES cell regulation.

Purpose of the Study:

• To identify novel proteins interacting with Dax1.
• To elucidate the regulatory role of Esrrb in the Oct3/4 network.
• To characterize the interaction between Dax1 and Esrrb.

Main Methods:

• Co-immunoprecipitation to confirm Dax1-Esrrb interaction.
• Luciferase reporter assays to assess promoter activity.
• Western blotting to analyze protein expression levels.
• Quantitative PCR to measure gene expression.

Main Results:

• Esrrb was identified as a Dax1-interacting protein.
• Esrrb enhances Dax1 gene promoter activity via direct binding.
• Esrrb regulates Dax1 expression independently of Oct3/4.
• Dax1 represses the transcriptional activity of Esrrb.
• Oct3/4, Dax1, and Esrrb exhibit competitive inhibition within their complexes.

Conclusions:

• Dax1 and Esrrb form a regulatory loop critical for ES cell pluripotency and self-renewal.
• Dax1 acts as a negative regulator for both Esrrb and Oct3/4.
• Esrrb can maintain Dax1 expression independently of Oct3/4, highlighting its regulatory role.