Arid1a is essential for intestinal stem cells through Sox9 regulation

Area of Science:

• Cell Biology
• Genetics
• Gastroenterology

Background:

• Inactivating mutations in ARID1A, a component of the SWI/SNF chromatin remodeling complex, are prevalent in human cancers.
• While intestinal ARID1A deletion induces colorectal cancer in mice, its specific role in intestinal homeostasis is not fully understood.

Purpose of the Study:

• To elucidate the functional significance of ARID1A in maintaining intestinal homeostasis and stem cell function in mice.

Main Methods:

• Intestinal deletion of Arid1a in adult mice.
• Lineage-tracing experiments in Lgr5+ intestinal stem cells (ISCs).
• Analysis of Wnt signaling pathway components and Sox9 expression.
• Sox9 overexpression studies in Arid1a-deficient intestinal epithelial cells.

Main Results:

• Intestinal Arid1a deletion led to loss of ISCs, reduced Paneth and goblet cells, disrupted crypt-villous structures, and increased apoptosis.
• Arid1a deficiency impaired Lgr5+ ISC self-renewal and downregulated Wnt signaling.
• Arid1a directly binds the Sox9 promoter, supporting its expression.
• Sox9 overexpression rescued ISC loss and spheroid formation defects but not Wnt signaling restoration.

Conclusions:

• ARID1A is indispensable for intestinal stem cell maintenance and homeostasis in mice, primarily through regulating SOX9 expression.
• These findings reveal key molecular mechanisms underlying intestinal stem cell regulation and homeostasis.