A regional regulatory axis shapes enteroendocrine cell morphology and function

Area of Science:

• Developmental Biology
• Cell Biology
• Gastrointestinal Physiology

Background:

• Enteroendocrine cells (EEs) are crucial gut epithelial cells with distinct open and closed morphologies.
• The molecular mechanisms driving EE morphological divergence are not fully understood.

Purpose of the Study:

• To elucidate the genetic basis for the regional specificity of closed EE morphology in the Drosophila midgut.
• To identify key regulators controlling EE cell form and function.

Main Methods:

• Utilized Drosophila melanogaster as a model organism.
• Investigated gene expression patterns and cell morphology in different midgut regions.
• Employed genetic manipulation to alter Ptx1 and escargot expression.

Main Results:

• Identified Ptx1 as a region-specific transcription factor essential for closed EE formation in the R3 midgut region.
• Demonstrated that Ptx1 maintains escargot (esg) expression, which suppresses smooth septate junction genes, preventing apical integration.
• Ectopic Ptx1 or esg expression induced closed EE morphology and impaired amino acid sensing in other regions.

Conclusions:

• A regional transcriptional regulatory axis involving Ptx1 and esg controls EE cell morphology in the Drosophila gut.
• EE morphology is directly linked to its luminal sensing capabilities, specifically for dietary amino acids.
• This study provides insights into the developmental mechanisms shaping gut epithelial cell diversity and function.