RFX6 regulates human intestinal patterning and function upstream of PDX1.

Area of Science:

• Developmental Biology
• Genetics
• Gastroenterology

Background:

• Congenital gastrointestinal malformations arise from rare gene variants, but their molecular basis is poorly understood.
• The gastrointestinal tract's complex development involves intricate patterning and signaling pathways.

Purpose of the Study:

• To investigate the molecular mechanisms by which RFX6 variants cause duodenal malformations.
• To elucidate the role of RFX6 in human intestinal development and regional identity.

Main Methods:

• Generated patient-derived induced pluripotent stem cells and human intestinal organoids (HIOs).
• Utilized CRISPR-mediated gene correction, gain- and loss-of-function studies, and transcriptomics in HIOs and Xenopus embryos.
• Analyzed regional identity of HIOs and human tissues.

Main Results:

• RFX6 variants led to mixed regional identity (gastric, ileal features) in duodenal HIOs and tissues.
• CRISPR correction of RFX6 restored normal duodenal identity.
• Identified PDX1 as a downstream target of RFX6 essential for duodenal development, alongside PDX1-independent pathways regulating GI tract regionalization.

Conclusions:

• RFX6 is a critical regulator of intestinal patterning and regional identity in the proximal intestine.
• RFX6 functions through both PDX1-dependent and independent transcriptional and signaling pathways to ensure proper GI tract development.