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An apoptotic endonuclease activated either by decreasing pH or by increasing calcium
M K Collins1, I J Furlong, P Malde
1CRC Centre for Cell and Molecular Biology, Chester Beatty Laboratories, London, UK.
Journal of Cell Science
|September 1, 1996
Summary
Researchers identified a novel endonuclease in mouse bone marrow cells. This enzyme fragments DNA when pH drops or calcium levels rise, potentially playing a role in apoptosis.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- DNA fragmentation is a hallmark of apoptosis.
- Specific endonucleases are implicated in DNA degradation during programmed cell death.
- The BAF3 cell line, dependent on Interleukin-3 (IL3), provides a model for studying cellular processes.
Purpose of the Study:
- To investigate the mechanisms of DNA fragmentation in BAF3 cells.
- To identify and characterize the endonuclease responsible for DNA cleavage.
- To explore the enzyme's potential role in apoptosis.
Main Methods:
- Induction of DNA fragmentation by altering pH and calcium concentrations in isolated BAF3 cell nuclei.
- Purification of the endonuclease from BAF3 cell nuclei.
- Analysis of DNA digestion products generated by the purified enzyme.
Main Results:
- DNA fragmentation in BAF3 nuclei was stimulated by decreasing pH below 6.5 or adding micromolar calcium.
- A novel endonuclease was purified 10,000-fold from BAF3 cell nuclei.
- The enzyme produced DNA fragments with 5'-hydroxyl and 3'-phosphate termini, distinct from other known mammalian endonucleases.
Conclusions:
- A unique calcium- and pH-sensitive endonuclease exists in BAF3 cells.
- This enzyme's characteristics suggest a specific role in DNA digestion during apoptosis.
- Further research is warranted to elucidate its precise function in programmed cell death.