Unformatted text preview: is in mammalian cells are
grouped as intrinisic or extrinsic pathways, which differ in their involvement of Bcl-2 family proteins and in the identity of the caspase that initates
One important role of apoptosis is the elimination of damaged cells, so
apoptosis is stimulated by many forms of cell stress, including DNA damage, viral infection, and growth factor deprivation. These stimuli activate the
intrinsic pathway of apoptosis, which leads to release of cytochrome c from
mitochondria and activation of caspase-9 (see Figure 17.8). As illustrated in
the following examples, the multiple signals that activate this pathway converge on regulation of the BH3-only members of the Bcl-2 family.
DNA damage is a particularly dangerous form of cell stress, because cells
with damaged genomes may have suffered mutations that can lead to the
development of cancer. DNA damage is thus one of the principal triggers of
programmed cell death, leading to the elimination of cells carrying potentially harmful mutations. As discussed in Chapter 16, seve...
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