Dietary methionine restriction improves colon tight junction barrier function and alters claudin expression pattern

Area of Science:

• Gastroenterology
• Cell Biology
• Nutritional Science

Background:

• Caloric restriction and dietary methionine restriction are known to increase longevity and prevent age-related diseases.
• Previous studies showed reduced methionine improved epithelial barrier function in cell cultures.

Purpose of the Study:

• To investigate the effect of dietary methionine restriction on tight junction (TJ) barrier function in rat gastrointestinal tissue.
• To determine if methionine restriction improves barrier function in a tissue model and for different epithelial cell types.

Main Methods:

• Rats were fed a methionine-restricted (MR) diet for 28 days.
• Transepithelial electrical resistance and paracellular diffusion of (14)C-D-mannitol were measured in colon mucosal sheets.
• RT-PCR and Western blot analysis were used to assess TJ protein composition (claudin-3, occludin).

Main Results:

• MR diet led to reduced plasma and colonocyte methionine levels.
• Improved barrier function was indicated by increased transepithelial electrical resistance and decreased mannitol diffusion.
• Increased claudin-3 abundance and altered occludin modification were observed, suggesting TJ alterations.

Conclusions:

• Dietary methionine restriction enhances epithelial barrier function in the rat colon.
• Altered tight junction protein composition is a key mechanism underlying this improvement.
• Methionine restriction may offer a dietary strategy to improve gastrointestinal health.