Tag Archives: Antioxidant

Ferritin

Ferritins, the senior proteins of iron metabolism by Paolo Arosio

Università degli Studi di Brescia , Department of Molecular and Translational Medicine, Brescia, Italy.

Why ferritins?

  • Ferritin is the first discovered molecule implicated in iron metabolism (1937), about a decade before transferrin.
  • It is among the most ancient molecules of life, expressed in all phila, from archea, eubacteria, plants, animals to humans.
  • It is the protein richest in iron, as it can contain up to thousands of iron atoms in a safe form.   
  • It is everywhere in the cell (cytosol, nucleus, mitochondria, plastids) and also in the extracellular space and body fluids, with various functions.
  • Its levels are tightly regulated by iron in animals and plants (and perhaps also in bacteria), serving as an indicator of cell and systemic iron status in most organisms
  • It is beautifully built by well-designed 4-helical-bundle subunits the make a shell – nanobox or nanocage – and it is so strong that it can withstand harsh conditions and large modifications of amino acid sequences
  • It has a flexible quaternary structure formed by one or more different subunit types that form a 24-mer shell, resulting in hundreds or thousands of different possible isoferritins
  • It is one thing with its iron, which is released and recycled only after protein disruption. Thi is done by a complex and regulated mechanism (ferritinophagy) that takes the protein to the lysosomes for its digestion .
  • Ferritin and transferrin set the foundation of the Bioiron Society, promoted by Pauline Harrison (the ferritin Lady) and Phil Eisen (the transferrin Lord)
  • Last but not least, ferritin and me (PA) have been together for more than 40 years.

What are Ferritins Good For?

  • What ferritins do? Ferritins are good, if not very good. Antioxidant: their ferroxidase activity positively competes with Fenton reaction for Fe(II) and H2O2, thus limiting the production of toxic free radicals in all organisms. Protection from death: they protect cells from apoptosis and probably also from ferroptosis.  Protection from infections: they protect mice from malaria, fishes and shell-fishes from various infections. Organ protection: they protect from cardiac complications, from from acute kidney diseases, from atherosclerosis and also cells from calcification. Other positive functions on photosynthesis, cell proliferation and other mechanisms have been described. 
  • Ferritins are bad only rarely. Few reports claimed that some ferritin types may promote apoptosis. Ferritin was found necessary for the progression of glioblastoma stem-like cells. When mutated the non-ferroxidase L-ferritin may cause neurodegeneration.
  • Ferritins are even useful. Because it their easy to produce, purify, store, and also because of it unique self-assembly and high stability properties, ferritins are the most used protein in bio-nanotechnology.  They are versatile biotech tools for encapsulating various molecules and ionic species, for synthesizing mineral cores, semiconductor particles and metal alloys and for carrying various epitopes/antigens. Ferritins have been used in the production of semiconductors and nanoelectronics, in drug delivery systems, in nanoparticles for biomedical diagnosis and more is to come.

In Summary:

The Ferritins have a remarkable history, are still much alive in present time and promise a bright future to those interested in them.

Download the article (A praise of Ferritin – by: P. AROSIO)