3. IRON METABOLISM
Dietary Iron:
Iron is essential element and must be
precisely regulated.
On the lumen side of small intestine iron is
reduced from its ferric form(Fe3+) to ferrous
form(Fe2+).
Ferrous iron is then transported in
enterocytes by DMT1(divalent metal
transporter).
4. Iron can be either stored within the
enterocyte as ferritin or it can be transferred
across the basolateral membrane to the
plasma by transport protein FERROPORTIN1
and MTP1.
(Requires oxidation of Ferrous to Ferric by
hephaestin.)
5. TRANSPORT PROTEINS
DMT1 (Divalent Metal Transporter 1)
(Tranports from lumen into the enterocytes)
FERROPORTIN1
(Transports from enterocytes to circulation)
8. What is HEPICIDIN??
Is a peptide hormone which was first
identified in human urine and plasma in 2000.
Its molecular weight is 25 Kda.
Highly folded structure.
Present in inactive form;prohepcidin(60aa)
and its active form is hepicidin(25aa).
10. Hepicidin, Primary regulator
Increased expression of hepicidin leads to
Decrease iron absorption and release.
Mutation :Hemochromatosis
Increased expression:Iron deficiency
Hepicidin mRna expression is increased by
erythropoetin,hypoxia & inflammation.
Also binds to ferroportin.
12. Mechanism of action of hepicidin
The major mechanism of hepicidin is THE
REGULATION OF TRANSMEMBRANE IRON
TRANSPORT.
It binds to FERROPORTIN ,forms hepicidin-
ferroportin complex ,which is degraded in the
lysosomes and iron is locked inside the
cells(mainly enterocytes,hepatocytes and
macrophages).
13. SO
• Hepcidin lowers iron absorption in the
intestine ,lowers iron releasing from
hepatocytes and macrophages
Serum iron is decreased.
14. Hepicidin Regulation
So when hepicidin levels are low ,iron exporting cells have abundant ferroportin and thus
releases iron into plasma.When hepicidin concentration increases it binds to ferroportin
and thus iron is retained in the cells.
16. Regulation of Hepcidin synthesis by
anemia and hypoxia
• Oxygen Hepcidin
Uptake of diet iron
Iron release from hepatocytes
Iron release from macrophages
17. Regulation of Hepcidin synthesis by
inflammation
Interleukin-6 Hepcidin
iron anemia of chronic
disease.
Generally when iron level ,ROS(Reactive
oxygen species) that leads to in
thiobarbutyric acid activation of NF Kappa
proteins activates IL-6 , hepicidin synthesis
19. The role of Hepcidin in hereditary
hemochromatosis
• Hereditary hemochromatosis:
-excessive intestinal iron absorption
-Saturation of transferrin
-Iron deposition in vital organs
20. Overall summary
Hepcidin
-Is a recently discovered liver produced 25
amino-acid peptide
-Is a regulator of iron metabolism that controls
iron absorption and macrophage iron release.
-Is regulated by erythropoietic needs( ) ,body
iron stores( ) and inflammation( )