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Unformatted text preview: ay of cell death. Autophagic cell death does not require
caspases and, rather than possessing the distinct morphological features of
apoptosis, the dying cells are characterized by an accumulation of lysosomes. Autophagy has been shown to be an important pathway of programmed cell death during salivary gland development in Drosophila and
to be induced by infection with some viruses. In addition, autophagy
appears to provide an alternative pathway to cell death when apoptosis is
blocked. For example, cells of mutant mice lacking Bak and Bax fail to
undergo apoptosis in response to stimuli such as DNA damage, as expected
since Bak and Bax are required for permeabilization of mitochondria (see
Figure 17.8). However, the Bak/Bax-deficient cells die by autophagy
instead, suggesting that autophagy may also be activated by cellular stress
and provide an alternative to apoptosis under these conditions.
It also appears that some forms of necrosis can be a programmed cellular
response, rather than simply representing uncontrolled cell lysis as the
result of an acute injury. In contrast to unregulated necrosis, these forms of
regulated necrotic cell death are indu...
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