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Poly(ADP-ribose) polymerase-1 in the nervous system
1Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA.
Abstract:
Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme, activated by DNA strand breaks to participate in DNA repair. Overactivation of PARP by cellular insults depletes its substrate NAD(+) and then ATP, leading to a major energy deficit and cell death. This mechanism appears to be prominent in vascular stroke and other neurodegenerative processes in which PARP gene deletion and PARP-inhibiting drugs provide major protection. Cell death associated with PARP-1 overactivation appears to be predominantly necrotic while apoptosis is associated with PARP-1 cleavage, which may conserve energy needed for the apoptotic process. Novel forms of PARP derived from distinct genes and lacking classic DNA-binding domains may have nonnuclear functions, perhaps linked to cellular energy dynamics.
Insights
Poly(ADP-ribose) polymerase-1 (PARP-1) overactivation causes cell death by depleting cellular energy. Inhibiting PARP-1 shows promise in protecting against neurodegenerative diseases like stroke.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme crucial for DNA repair.
- PARP-1 activation by DNA damage can lead to cellular energy depletion (NAD+ and ATP loss) and cell death.
- This energy depletion mechanism is implicated in neurodegenerative conditions such as vascular stroke.
Purpose of the Study:
- To investigate the role of PARP-1 overactivation in cell death mechanisms.
- To explore the protective effects of PARP inhibition in neurodegenerative processes.
- To examine the distinct functions of novel PARP forms.
Main Methods:
- Enzyme activity assays
- Gene deletion studies
- Pharmacological inhibition of PARP
- Cell death pathway analysis (necrosis vs. apoptosis)
Main Results:
- PARP-1 overactivation leads to significant NAD+ and ATP depletion, resulting in cell death.
- PARP gene deletion and PARP-inhibiting drugs demonstrate substantial neuroprotection in models of stroke.
- PARP-1 overactivation predominantly induces necrotic cell death, whereas PARP-1 cleavage is linked to apoptosis.
- Novel PARP variants may possess non-nuclear functions related to cellular energy.
Conclusions:
- PARP-1 overactivation is a key driver of cell death in neurodegenerative conditions due to energy depletion.
- Targeting PARP-1 offers a promising therapeutic strategy for neuroprotection in stroke and related disorders.
- Distinct PARP family members may have diverse roles in cellular energy homeostasis and non-nuclear functions.