Figure 5.

PARP-1-dependent signalling in apoptosis. Excessive oxidative stress leads to hyperactivation of PARP-1 in the nucleus. PAR formation and NAD⁺ depletion can trigger a cascade of events which can lead to the release of apoptotic inducing factor (AIF). AIF can migrate to the nucleus where it can trigger cell death. AIF can also promote release of cytochrome c (cyt c) through upregulation of Beclin-2 protein (Bcl-2) which can cause apoptosis via a downstream signalling through caspase activation.