Internalization and Decrease of Duodenal DMT1 Involved in Transient Suppression of Iron Uptake in Short-Acting...

Area of Science:

• Physiology
• Nutritional Science
• Gastroenterology

Background:

• Oral iron administration can induce a mucosal block (MB), suppressing intestinal iron absorption.
• A recently identified short-acting mucosal block (SAMB) involves transient iron uptake suppression without gene changes, specific to iron-deficient rats.
• The roles of nonheme iron transporters, divalent metal transporter 1 (DMT1) and ferroportin (FPN), in SAMB remain unclear.

Purpose of the Study:

• To investigate the involvement of DMT1 and FPN in the transient suppression of iron uptake during SAMB.
• To elucidate the molecular mechanisms underlying SAMB in iron-deficient rats.

Main Methods:

• SAMB was induced by infusing 1 mg of iron into the duodenal loop of iron-sufficient and iron-deficient rats.
• Duodenal tissue was analyzed for DMT1 and FPN expression and intracellular distribution using fluorescence intensity and puncta imaging.
• Changes in DMT1-IRE protein levels and localization were assessed at 15 and 60 minutes post-iron loading.

Main Results:

• Iron deficiency increased total duodenal DMT1 and DMT1-IRE expression.
• Following 1 mg iron loading, duodenal DMT1 fluorescence intensity decreased in iron-deficient rats to levels similar to iron-sufficient rats.
• Internalization of DMT1-IRE into puncta increased significantly at 60 minutes post-iron loading; FPN intracellular distribution was unaffected.

Conclusions:

• The decrease and internalization of DMT1-IRE protein are likely involved in the iron uptake suppression observed in SAMB.
• SAMB represents a rapid, post-transcriptional regulatory mechanism for intestinal iron absorption.
• These findings highlight DMT1's dynamic regulation in response to luminal iron availability.