Related Experiment Video
Updated: Jun 23, 2026
09:43
Measurement of Heme Synthesis Levels in Mammalian Cells
Published on: July 9, 2015
Ferritin metabolism in reticulated-siderocytes
The Journal of Clinical Investigation
|March 1, 1970
Summary
Reticulated-siderocytes rapidly lose iron granules, releasing soluble ferritin. This process is oxygen-dependent, with monocytes then taking up the ferritin, forming a novel reticulocyte-plasma-monocyte iron pathway.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Reticulated-siderocytes, a specific type of reticulocyte containing siderotic granules, are found in circulation.
- Iron metabolism in these cells and its subsequent fate is not fully understood.
Purpose of the Study:
- To investigate the in vitro behavior of siderotic granules within reticulated-siderocytes.
- To elucidate the metabolic pathways involved in granule degradation and ferritin release.
- To determine the interaction of monocytes with released ferritin.
Main Methods:
- Incubation of reticulated-siderocytes obtained from pigs post-phlebotomy.
- Monitoring of siderotic granule disappearance and soluble ferritin accumulation in the media over 24 hours.
- Assessment of oxygen dependency and the effect of metabolic inhibitors (cyanide, dinitrophenol).
- Observation of ferritin uptake and granule formation in monocytes.
Main Results:
- Siderotic granules rapidly disappeared from reticulated-siderocytes within 24 hours.
- Soluble ferritin accumulated in the incubation media concurrently with granule loss.
- Granule disappearance and ferritin release were oxygen-dependent and inhibited by cyanide and dinitrophenol.
- Monocytes acquired soluble ferritin from the media and formed new siderotic granules.
Conclusions:
- Ferritin aggregates within reticulated-siderocyte granules are dispersed intracellularly into soluble ferritin.
- Soluble ferritin is excreted from the cell, a process dependent on oxidative metabolism.
- Blood monocytes actively uptake soluble ferritin and convert it into siderotic granules.
- A novel reticulocyte-plasma-monocyte pathway for ferritin transport has been identified.
Related Concept Videos
01:28The Early Endosome: Endocytosis of Transferrin
Essential proteins such as insulin or low-density lipoprotein (LDL) and micronutrients such as iron enter a eukaryotic cell through receptor-mediated endocytosis. Subsequently, the early endosomes fuse with the vesicles containing such receptor-ligand complexes and play a vital role in sorting the incoming ligands and receptors. While the ligands are either degraded inside the vesicle or released into the cytosol, their receptors are returned to the plasma membrane for further rounds of...
01:14Erythropoiesis
Red blood cells (RBCs) transport oxygen to all body tissues. These cells survive only for 120 days and then need to be replenished. Erythropoiesis is the process of RBC production. In healthy individuals, erythropoiesis ensures all tissues are amply supplied with oxygen. In addition, blood loss due to injury leads to a drop in the physiological oxygen level that will cause erythropoiesis. Any defect in erythropoiesis leads to several physiological disorders, including thalassemia, anemia, and...
01:22Lifecycle of Erythrocytes
Erythrocytes, also known as red blood cells, constantly move through blood capillaries. As a result, they damage their plasma membrane due to the continuous friction. Typically, after 100 to 120 days, erythrocytes become rigid and fragile as they wear out. As they pass through small vessels in the spleen and liver, they can get trapped and break apart into fragments.
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
01:28Microbial Nutrition
Organisms exhibit remarkable metabolic diversity, categorized based on how they acquire energy and carbon. These strategies enable survival in various ecological niches and are essential for maintaining energy flow and nutrient cycling within ecosystems.Energy and Carbon SourcesOrganisms are classified as phototrophs or chemotrophs based on energy acquisition. Phototrophs use light as their energy source, while chemotrophs rely on oxidizing chemical compounds. Further differentiation arises...
01:20Sulfur Assimilation
Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to become...
01:24Microbes and Other Elemental Cycles
Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of stratified aquatic environments. These cycles are driven by microbial transformations between oxidized and reduced forms of the metals, allowing organisms to exploit them for metabolic energy and structural purposes.Iron Cycling Across Redox GradientsIn neutral, oxygen-rich surface waters, iron is predominantly found in its oxidized, insoluble ferric...