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Published on: December 19, 2010
Ca2+/Mg(2+)-dependent endonuclease in marrow CD34 positive and erythroid cells in myelodysplasia
N Anzai1, H Kawabata, T Hishita
1Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Japan.
Abstract:
Endonucleases capable of producing internucleosomal DNA cleavage are one of the key enzymes in apoptosis. We examined endonuclease activities contained in nuclei of CD34+ and erythroid cells in the bone marrow (BM) from 12 patients with the myelodysplastic syndromes. The levels of Mg(2+)-dependent and acidic endonucleases showed little changes as compared with those from normal BM. By contrast, the level of Ca2+/Mg(2+)-dependent endonuclease was appreciably higher in MDS erythroid cells than normal counterparts, although the activity varied markedly in CD34+ and erythroid cells. Our results suggested that Ca2+/Mg(2+)-dependent endonuclease is related to ineffective erythropoiesis in MDS.
Insights
Ca2+/Mg(2+)-dependent endonuclease activity is elevated in myelodysplastic syndromes (MDS) erythroid cells, suggesting a link to ineffective erythropoiesis. This finding highlights a potential mechanism in MDS pathogenesis.
Area of Science:
- Molecular Biology
- Cell Biology
- Hematology
Background:
- Endonucleases are key enzymes in apoptosis, responsible for internucleosomal DNA cleavage.
- Myelodysplastic syndromes (MDS) are a group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis and increased risk of transformation to acute myeloid leukemia.
Purpose of the Study:
- To investigate the activity of different endonuclease types in bone marrow (BM) CD34+ and erythroid cells from MDS patients.
- To determine the relationship between specific endonuclease activities and ineffective erythropoiesis in MDS.
Main Methods:
- Analysis of endonuclease activities (Mg(2+)-dependent, acidic, and Ca(2+)/Mg(2+)-dependent) in nuclear extracts from bone marrow CD34+ and erythroid cells.
- Comparison of enzyme levels between 12 MDS patients and normal bone marrow counterparts.
Main Results:
- Mg(2+)-dependent and acidic endonuclease levels showed minimal changes in MDS cells compared to normal BM.
- Ca(2+)/Mg(2+)-dependent endonuclease activity was significantly higher in MDS erythroid cells than in normal erythroid cells.
- Endonuclease activity levels exhibited considerable variation within CD34+ and erythroid cell populations in MDS.
Conclusions:
- The elevated Ca(2+)/Mg(2+)-dependent endonuclease activity in MDS erythroid cells is strongly associated with ineffective erythropoiesis.
- This specific endonuclease may play a crucial role in the pathogenesis of ineffective erythropoiesis observed in myelodysplastic syndromes.
