Small DNA fragments isolated from human T-cell clones are enriched in sequences involved in DNA bending.
IL-2 deprivation induces apoptosis in human IL-2-dependent T-cell clones. This process is characterized by typical cell morphology, changes in the cellular membranes and fragmentation of chromatin into units of single and multiple nucleosomes. We isolated apoptotic DNA of an IL-2-deprived T-cell clone and sequenced randomly selected fragments representing single and multiple nucleosomes.The frequency of phased adenosine tracts was markedly increased in the small apoptotic fragments as compared to oligonucleosomes. Our results thus indicate that chromatin fragmentation in human apoptotic T-cells is not random but preferentially involves DNA sequences with the capability to form bent DNA. Whether this indicates a colocalization of DNase cleavage sites and phased adenosine tracts on the chromosomes or a bias in selecting sites for apoptotic DNA fragmentation is discussed. Analysing the underlying mechanisms will shed new light on DNA degradation in apoptosis.
Herrmann
M
M
Institute of Clinical Immunology and Rheumatology, Department of Medicine III, Friedrich-Alexander-University, Erlangen, Germany.
Voll
R
R
Woith
W
W
Hagenhofer
M
M
Lorenz
H M
HM
Manger
B
B
Kalden
J R
JR