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Impaired protein synthesis in erythroblasts enhances their phagocytosis by macrophages
Abstract:
In an attempt to elucidate mechanisms which underly ineffective erythropoiesis, we investigated the effect of impaired macromolecular synthesis in erythroblasts on their phagocytosis by macrophages in vitro. Dimethylsulphoxide-induced murine Friend leukaemia erythroblasts were treated with inhibitors of RNA or protein synthesis and subsequently tested for their interaction with syngeneic mouse peritoneal macrophages in culture. Exposure of the erythroblasts to two reversible inhibitors of protein synthesis, puromycin and cycloheximide, enhanced their association with and phagocytosis by macrophages. The effect was evident after the drugs had caused a partial inhibition of protein synthesis and appeared to be reversible. By contrast, the treatment of erythroblasts with the inhibitor of RNA-synthesis, actinomycin D, which caused a marked depression of RNA but not of protein synthesis, failed to affect the interaction of erythroblats with macrophages. The results are in keeping with previous observations on human bone marrow showing impaired protein synthesis in erythroblasts in some haematological disorders characterized by a marked increase in ineffective erythropoiesis.
Insights
Impaired protein synthesis in erythroblasts, but not RNA synthesis, increases their phagocytosis by macrophages. This finding sheds light on ineffective erythropoiesis mechanisms in certain blood disorders.
Area of Science:
- Hematology
- Cell Biology
- Immunology
Background:
- Ineffective erythropoiesis is a hallmark of several hematological disorders.
- The mechanisms underlying ineffective erythropoiesis, particularly the role of erythroblast macromolecular synthesis, require further elucidation.
Purpose of the Study:
- To investigate the impact of impaired macromolecular synthesis in erythroblasts on their phagocytosis by macrophages.
- To explore the relationship between protein synthesis inhibition and erythroblast-macrophage interactions in vitro.
Main Methods:
- Murine Friend leukaemia erythroblasts were treated with inhibitors of RNA or protein synthesis (puromycin, cycloheximide, actinomycin D).
- Erythroblast interaction and phagocytosis by syngeneic mouse peritoneal macrophages were assessed in cell culture.
Main Results:
- Reversible inhibition of protein synthesis enhanced erythroblast association with and phagocytosis by macrophages.
- Inhibition of RNA synthesis did not affect erythroblast-macrophage interactions.
- These findings correlate with observations of impaired protein synthesis in erythroblasts in human bone marrow disorders.
Conclusions:
- Impaired protein synthesis, rather than RNA synthesis, in erythroblasts contributes to their increased phagocytosis.
- This study provides insights into cellular mechanisms contributing to ineffective erythropoiesis.
- The findings may have implications for understanding hematological disorders characterized by ineffective erythropoiesis.