Premium
Activation of DNA‐Dependent Protein Kinase May Play a Role in Apoptosis of Human Neuroblastoma Cells
Author(s) -
Chakravarthy Balu R,
Walker Teena,
Rasquinha Ingrid,
Hill Irene E,
MacManus John P
Publication year - 1999
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1999.0720933.x
Subject(s) - staurosporine , dna fragmentation , apoptosis , microbiology and biotechnology , programmed cell death , biology , dna laddering , fragmentation (computing) , protein kinase a , apoptotic dna fragmentation , dna damage , dna , kinase , biochemistry , ecology
: Treating SH‐SY5Y human neuroblastoma cells with 1μ M staurosporine resulted in a three‐ to fourfold higherDNA‐dependent protein kinase (DNA‐PK) activity compared with untreated cells.Time course studies revealed a biphasic effect of staurosporine on DNA‐PKactivity : an initial increase that peaked by 4 h and a rapid decline thatreached ~5‐10% that of untreated cells by 24 h of treatment. Staurosporineinduced apoptosis in these cells as determined by the appearance ofinternucleosomal DNA fragmentation and punctate nuclear morphology. Themaximal stimulation of DNA‐PK activity preceded significant morphologicalchanges that occurred between 4 and 8 h (40% of total number of cells) andincreased with time, reaching 70% by 48 h. Staurosporine had no effect oncaspase‐1 activity but stimulated caspase‐3 activity by 10‐15‐fold in atime‐dependent manner, similar to morphological changes. Similartime‐dependent changes in DNA‐PK activity, morphology, and DNA fragmentationoccurred when the cells were exposed to either 100 μ M ceramide or UV radiation. In all these cases the increase in DNA‐PK activity preceded the appearance of apoptotic markers, whereas the loss in activity was coincident with cell death. A cell‐permeable inhibitor of DNA‐PK, OK‐1035, significantly reduced staurosporine‐induced punctate nuclear morphology and DNA fragmentation. Collectively, these results suggest an intriguing possibility that activation of DNA‐PK may be involved with the induction of apoptotic cell death.