Physiology

Dying For Iron

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Science  25 Jan 2008:
Vol. 319, Issue 5862, pp. 387
DOI: 10.1126/science.319.5862.387a

Food supplements, such as the blue-green alga popularly referred to as spirulina, are used worldwide and can serve as valuable sources of vitamins and minerals. Iron is one of the many elements that are needed for life yet are toxic in excess. In the small intestine—particularly in the first 12-finger-width segment known as the duodenum—epithelial cells express the iron-regulatory proteins (IRP1 and IRP2) that maintain iron homeostasis by adjusting the expression of proteins that absorb, metabolize, and export this essential dietary component. By selectively eliminating the expression of IRPs in these cells in mice, Galy et al. demonstrate that they are also required for intestinal development. They observed that mice deficient in IRPs suffered from weight loss and dehydration and died a few weeks after birth. Surprisingly, the mice manifested close to normal blood and liver iron content; on the other hand, intestinal villi were malformed, and duodenal epithelia displayed degenerated mitochondria (perhaps a sign of diminished iron-sulfur cluster synthesis) and increased cell death, which probably contributed to impaired water and nutrient absorption. Thus, although the absence of IRPs in the intestinal epithelium does not acutely alter systemic iron levels, it does affect intracellular processes that control intestinal morphogenesis and survival. — LDC

Cell Metab. 7, 79 (2008).

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