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Caspase-activated DNase/DNA fragmentation factor 40 mediates apoptotic DNA fragmentation in transient cerebral

G Cao1, W Pei, J Lan

  • 1Department of Neurology, Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
|June 27, 2001
PubMed

Insights

This study identifies caspase-activated deoxyribonuclease (CAD)/DNA fragmentation factor 40 (DFF40) as the key enzyme responsible for DNA fragmentation in ischemic neurons. This finding elucidates a crucial mechanism in neuronal apoptosis following brain insults.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Biochemistry

Background:

  • Neuronal apoptosis involves nuclear changes like DNA fragmentation, but the precise molecular mechanisms in cerebral ischemia remain unclear.
  • Caspase-3 is a suspected mediator of nuclear degradation in ischemic neurons.

Purpose of the Study:

  • To elucidate the molecular mechanism of internucleosomal DNA fragmentation in ischemic neurons.
  • To investigate the role of caspase-activated deoxyribonuclease (CAD)/DNA fragmentation factor 40 (DFF40) in neuronal apoptosis after transient global ischemia.

Main Methods:

  • Cloning of rat brain homolog cDNA encoding CAD/DFF40.
  • Investigating CAD/DFF40 expression and activity in vivo (rat model of transient global ischemia) and in vitro (primary neuronal cultures under ischemia-like conditions).
  • Assessing CAD/DFF40 activation via caspase-3 and its interaction with its inhibitor ICAD.

Main Results:

  • CAD/DFF40 mRNA and protein were induced in hippocampal CA1 neurons post-ischemia (8-72 hr).
  • Ischemia induced delayed activation (>24 hr) of CAD/DFF40 by nuclear translocation and ICAD cleavage by caspase-3.
  • CAD/DFF40 DNA degradation activity was confirmed in nuclear extracts and inhibited by ICAD.

Conclusions:

  • CAD/DFF40 is the endogenous endonuclease mediating caspase-3-dependent internucleosomal DNA degradation in ischemic neurons.
  • This research clarifies a key pathway in nuclear alterations during neuronal apoptosis in brain insults.

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