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Immunocytochemical study on microtubule reorganization in HL-60 leukemia cells undergoing apoptosis
Shahin Ahmadian1, Yaghub Pazhang1, Ahmad Shariftabrizi1
1Department of Biochemistry, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
Background:
Microtubules (MT) are important components of cell cytoskeleton and play key roles in cell motility mitosis and meiosis. They are also the targets of several anticancer agents which indicating their importance in maintaining cell viability. Microtubular reorganization contributing to apoptotic morphology occurs in normal and neoplastic cells undergoing apoptosis induced by cytotoxic drugs. The aim of this study was to correlate the changes in the MT with behavior of the gamma-tubulin in apoptotic cell, and to see if apoptitic MT showed biochemical characteristics of stable MT.
Methods:
Apoptosis was induced in the human leukemia cells (HL-60) by treatment with 1 microM of all-trans retinoic acid over a 5-day period. The time course of changes was assessed using flow cytometry, DNA fragmentation and immunocytochemistry in cells labeled for alpha-tubulins, acetylated alpha-tubulin and gamma-tubulin.
Results:
The results indicated that gamma-tubulin content is increased after cells have gone through the apoptosis with a diffuse cytoplasmic pattern. Alpha-tubulin did not reveal any specific pattern of polymerization in apoptotic cells and acetylated alpha-tubulin content was also decreased in comparison with non-apoptotic cells.
Conclusion:
Our results support the idea that microtubule reorganization is an important factor of the mammalian cells response to apoptosis, and the altered properties of the MT did not reflect changes in function as apoptosis progresses.
Insights
Microtubule reorganization is key in mammalian cell apoptosis. Gamma-tubulin increases, while alpha-tubulin and acetylated alpha-tubulin levels change, indicating altered microtubule properties during programmed cell death.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Microtubules (MT) are crucial for cell motility, mitosis, and meiosis.
- Microtubules are vital for cell viability and are targets for anticancer drugs.
- Microtubule reorganization is observed during apoptosis induced by cytotoxic drugs.
Purpose of the Study:
- To correlate changes in microtubules with gamma-tubulin behavior during apoptosis.
- To determine if apoptotic microtubules exhibit characteristics of stable microtubules.
Main Methods:
- Apoptosis was induced in human leukemia (HL-60) cells using all-trans retinoic acid over 5 days.
- Flow cytometry, DNA fragmentation, and immunocytochemistry were used to assess changes.
- Cells were labeled for alpha-tubulin, acetylated alpha-tubulin, and gamma-tubulin.
Main Results:
- Gamma-tubulin content increased in a diffuse cytoplasmic pattern post-apoptosis.
- Alpha-tubulin showed no specific polymerization pattern in apoptotic cells.
- Acetylated alpha-tubulin levels decreased compared to non-apoptotic cells.
Conclusions:
- Microtubule reorganization is a significant response in mammalian cells undergoing apoptosis.
- Altered microtubule properties during apoptosis do not necessarily reflect functional changes as the process progresses.
