Protein of life, protein of death
The same enzyme regulates programmed cell death and embryonic development
By Andrea Rinaldi

Complex, multicellular organisms must finely regulate their inner
environment to assure cells can thrive, but must also initiate apoptosis
(programmed cell death) when necessary. Apoptosis is critical for normal
development and tissue homeostasis, and aberrant apoptosis can lead to
cancer and neural degeneration. In a PNAS article published online December
8, Jianhua Zhang and colleagues at the University of Cincinnati College of
Medicine pinpoint an enzyme that plays an important role in both the
regulation of normal apoptosis and embryogenesis in mammals (PNAS,
DOI:10.1073/pnas.2636393100, December 8, 2003).

Zhang et al. investigated the in vivo function of endonuclease G (EndoG), a
mitochondrial protein encoded in the nucleus, previously reported to be
important for nuclear DNA fragmentation during apoptosis and mitochondrial
DNA replication. The authors studied the consequences of EndoG deficiency in
mice and observed that homozygous mutant embryos died early during
development and had lost normal morphology, while heterozygous animals
developed normally. Mitochondrial numbers were the same in mutant and
wildtype mice, suggesting that EndoG is not involved in mitochondrial DNA
replication. The authors also observed that EndoG mutant cells subjected to
apoptotic stimuli were more resistant to cell death than wildtype control
cells.

Read the rest at The Scientis.com
http://www.biomedcentral.com/news/20031209/02

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