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Updated: May 10, 2026
Isolation of Mouse Megakaryocyte Progenitors
Published on: May 20, 2021
Synergistic effect of hydrogen peroxide on polyploidization during the megakaryocytic differentiation of K562
Yoshihiro Ojima1, Mark Thompson Duncan, Retno Wahyu Nurhayati
1Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan. ojima@cheng.es.osaka-u.ac.jp
Abstract:
The human myelogenous cell line, K562 has been extensively used as a model for the study of megakaryocytic (MK) differentiation, which could be achieved by exposure to phorbol 12-myristate 13-acetate (PMA). In this study, real-time PCR analysis revealed that the expression of catalase (cat) was significantly repressed during MK differentiation of K562 cells induced by PMA. In addition, PMA increased the intracellular reactive oxygen species (ROS) concentration, suggesting that ROS was a key factor for PMA-induced differentiation. PMA-differentiated K562 cells were exposed to hydrogen peroxide (H2O2) to clarify the function of ROS during MK differentiation. Interestingly, the percentage of high-ploidy (DNA content >4N) cells with H2O2 was 34.8±2.3% at day 9, and was 70% larger than that without H2O2 (21.5±0.8%). Further, H2O2 addition during the first 3 days of PMA-induced MK differentiation had the greatest effect on polyploidization. In an effort to elucidate the mechanisms of enhanced polyploidization by H2O2, the BrdU assay clearly indicated that H2O2 suppressed the division of 4N cells into 2N cells, followed by the increased polyploidization of K562 cells. These findings suggest that the enhancement in polyploidization mediated by H2O2 is due to synergistic inhibition of cytokinesis with PMA. Although H2O2 did not increase ploidy during the MK differentiation of primary cells, we clearly observed that cat expression was repressed in both immature and mature primary MK cells, and that treatment with the antioxidant N-acetylcysteine effectively blocked and/or delayed the polyploidization of immature MK cells. Together, these findings suggest that MK cells are more sensitive to ROS levels during earlier stages of maturation.
Insights
Reactive oxygen species (ROS) enhance megakaryocytic differentiation and polyploidization in K562 cells by inhibiting cell division. ROS also appear crucial for primary megakaryocyte maturation, despite not directly increasing ploidy.
Area of Science:
- Cell Biology
- Hematopoiesis
- Oxidative Stress Research
Background:
- K562 cells are a model for megakaryocytic (MK) differentiation induced by phorbol 12-myristate 13-acetate (PMA).
- Catalase (cat) expression is repressed during PMA-induced MK differentiation.
- PMA treatment increases intracellular reactive oxygen species (ROS) concentration.
Purpose of the Study:
- To investigate the role of ROS in PMA-induced MK differentiation and polyploidization.
- To elucidate the mechanisms by which ROS influence K562 cell polyploidization.
- To examine ROS sensitivity in primary MK cells during maturation.
Main Methods:
- Real-time PCR to analyze catalase gene expression.
- Flow cytometry to measure intracellular ROS concentration and DNA content (ploidy).
- Bromodeoxyuridine (BrdU) assay to assess cell division.
- Treatment with hydrogen peroxide (H2O2) and N-acetylcysteine (antioxidant).
Main Results:
- Hydrogen peroxide (H2O2) significantly increased polyploidization in PMA-differentiated K562 cells.
- H2O2 addition, especially early in differentiation, enhanced polyploidization by suppressing 4N cell division.
- Catalase expression was repressed in primary immature and mature MK cells; N-acetylcysteine delayed polyploidization in immature MK cells.
Conclusions:
- ROS, particularly H2O2, synergistically inhibit cytokinesis with PMA, enhancing polyploidization in K562 cells.
- Primary MK cells exhibit sensitivity to ROS levels during early maturation stages.
- These findings highlight the critical role of oxidative stress in megakaryopoiesis.
