How does ferroportin contribute to maintaining iron levels?
Ferroportin is the sole cellular efflux channel for iron and is regulated by the iron regulatory hormone hepcidin, which binds ferroportin and induces its internalization and degradation. New studies of ferroportin knockout mice define a key role for this transporter in physiological iron balance.
What protein causes anemia by inhibiting ferroportin?
In the first group, anemia is due to the inhibitory effect exerted by hepcidin on iron absorption and recycling that leads to systemic iron deficiency; in the second group, anemia is due to hepcidin suppression by an expanded abnormal erythropoiesis (Camaschella and Nai, 2016). Figure 1.
What does hepcidin do to ferroportin?
The serum level of iron in humans is tightly controlled by the action of the hormone hepcidin on the iron efflux transporter ferroportin. Hepcidin regulates iron absorption and recycling by inducing the internalization and degradation of ferroportin1.
What happens to hepcidin in iron deficiency?
Serum hepcidin is increased by high iron stores, blocks intestinal iron absorption, and impairs storage iron release. Conversely, iron deficiency lowers hepcidin levels and enhances intestinal iron absorption and the release of storage iron. As with ferritin, hepcidin is an acute phase reactant.
How is Ferroportin regulated?
Ferroportin is regulated by hepcidin, a hormone produced by the liver; hepcidin binds to Fpn and limits its iron-efflux activity, thereby reducing iron delivery to the blood plasma. Therefore, the interaction between Fpn and hepcidin controls systemic iron homeostasis.
Where is ferroportin found?
Ferroportin is found on the basolateral membranes of intestinal epithelia of mammals, including: Enterocytes in the duodenum. Hepatocytes. Macrophages of the reticuloendothelial system.
How does hepcidin hinder ferroportin activity?
When hepcidin levels are high, hepcidin binds and occludes the central cavity, which prevents the conformational transition and iron export. When hepcidin levels decrease under iron deficiency, hepcidin does not occupy the central cavity, which enables Fpn to resume iron export.
Does hepcidin increase iron absorption?
Conversely, hepcidin is suppressed in iron deficiency, allowing increased absorption of dietary iron and replenishment of iron stores. Increased erythropoietic activity also suppresses hepcidin production.
What is driving iron through ferroportin?
Ferroportin is a transmembrane protein that transports iron from the inside of a cell to the outside of the cell. Ferroportin is the only known iron exporter. After dietary iron is absorbed into the cells of the small intestine, ferroportin allows that iron to be transported out of those cells and into the bloodstream.
What cells have ferroportin?
Early work confirmed that ferroportin is highly expressed by cells and tissues associated with iron transport: duodenal enterocytes, liver Kupffer cells and splenic red pulp macrophages, periportal hepatocytes, and the placental syncytiotrophoblast (Figure 1).
What is ferroportin-associated iron overload?
Ferroportin-associated iron overload is an autosomal dominant disorder in iron metabolism resulting from a mutation of the SLC40A1 gene on chromosome 2q32. 60 The ferroportin protein is normally involved in iron transport out of macrophages; consequently, ferroportin mutation results in an accumulation of iron in hepatic macrophages.
Does ferroportin or hepcidin have a direct anti-bacterial effect in macrophages?
Ferroportin (via hepcidin) mediates iron sequestration in response to infection and controls proliferation of intracellular bacteria (Theurl et al., 2008; Zhang et al., 2011 ), although it is controversial whether ferroportin or hepcidin in macrophages exerts a direct anti-bacterial effect ( Nairz et al., 2018 ).
Where is ferritinoprotein (Fpn) expressed?
In mammals, FPN is expressed at high levels in cell types that play key roles in iron metabolism, including at the basolateral membrane of duodenal enterocytes ( Fig. 12.2 ), in hepatic and splenic macrophages ( Fig. 12.2B ), and in placental syncytiotrophoblasts [ 290–292, 294, 295 ].
What is ferferroportin (SLC40A1)?
Ferroportin (SLC40A1) is a transporter that plays a role in intestinal absorption of iron and also in the release of iron from the interior of a cell.
