Ash2l interacts with Oct4-stemness circuitry to promote super-enhancer-driven pluripotency network

Area of Science:

• Cell Biology
• Epigenetics
• Developmental Biology

Background:

• Super-enhancers regulate cell fates, but their precise mechanisms in pluripotency remain unclear.
• Understanding stemness gene regulation is key to controlling cell differentiation and self-renewal.

Purpose of the Study:

• To elucidate the mechanism by which Ash2l regulates pluripotency and self-renewal in pluripotent stem cells.
• To identify the direct role of Ash2l in modulating super-enhancer activity of stemness genes.

Main Methods:

• Investigated Ash2l's interaction with super-enhancers of key pluripotency genes (Jarid2, Nanog, Sox2, Oct4).
• Utilized Ash2l knockdown and CRISPRi/dCas9-mediated gene editing to assess functional impact.
• Examined the role of Ash2l-Oct4 interaction using a W118A mutation in rescue experiments.

Main Results:

• Ash2l directly binds to super-enhancers of stemness genes, recruiting the Oct4/Sox2/Nanog (OSN) complex.
• Ash2l knockdown or disruption of its binding motifs abrogated OSN recruitment and enhancer activation.
• Ash2l-Oct4 interaction is essential for Ash2l-mediated enhancer activation and pluripotency gene upregulation.

Conclusions:

• Ash2l forms an enhancer-bound complex with OSN to drive enhancer activation and maintain the pluripotent circuitry.
• This mechanism highlights Ash2l's critical role in governing the pluripotency network and stemness circuitry.
• The findings provide novel insights into the epigenetic regulation of stem cell identity.