Related Experiment Videos
Hemosomegenesis and hemoglobin biosynthesis in vertebrates
A Brunner Júnior1, E de Rizzo, D D Morena
1Laboratories of Electron Microscopy, Instituto Butantan, São Paulo, Brasil.
Summary
Researchers discovered novel hemoglobinized organelles, termed hemosomes, within erythroid cells. These hemosomes are crucial sites for hemoglobin biosynthesis and are present across vertebrate classes.
Area of Science:
- Cell Biology
- Hematology
- Biochemistry
Background:
- Erythroid cells are responsible for hemoglobin synthesis.
- The precise intracellular sites of hemoglobin biosynthesis have been debated.
- Mitochondria play a role in cellular energy production and heme synthesis.
Purpose of the Study:
- To identify and characterize novel organelles involved in hemoglobin biosynthesis.
- To investigate the role of these organelles in erythroid cell maturation.
- To determine the presence and function of these organelles across different vertebrate species.
Main Methods:
- Ultrastructural analysis of maturing rabbit embryo erythroid cells.
- Biochemical assays including electrophoresis to confirm hemoglobin content.
- Experimental induction of hemoglobin synthesis in cultured non-erythroid cells.
- Comparative analysis of hemosome frequency in different erythroid cell populations and conditions.
Main Results:
- Identified hemoglobinized organelles (hemosomes) distinct from mitochondria in rabbit erythroid cells.
- Confirmed hemoglobin presence within isolated hemosomes via electrophoresis.
- Observed higher hemosome frequency in peripheral blood erythroid cells correlating with higher hemoglobin synthesis rates.
- Demonstrated hemosome formation and dependence on erythropoietin in induced HeLa and epithelial cells.
- Elucidated the sequential process of hemosomegenesis involving mitochondria differentiation and accumulation of heme and globin components.
- Detected hemosomes and organellar hemoglobin in immature erythrocytes of various vertebrates, including mammals, birds, reptiles, amphibians, and fish.
Conclusions:
- Hemosomes are proposed as the primary sites for heme integration and globin chain assembly in hemoglobin biosynthesis.
- Hemosome formation is tightly linked to the rate of hemoglobin synthesis and erythropoietin induction.
- The identified hemosome dynamics and organellar hemoglobin are conserved across vertebrate erythroid maturation.