Parkin and PINK1 mitigate STING-induced inflammation

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Parkinson's disease (PD) is linked to elevated pro-inflammatory cytokines, but the role of inflammation in neurodegeneration is unclear.
• Mutations in parkin (PRKN) and PINK1 cause early-onset PD and are involved in mitophagy, a pathway for removing damaged mitochondria.
• The in vivo function of mitophagy and its connection to inflammation remain poorly understood, partly due to a lack of relevant phenotypes in knockout mice.

Purpose of the Study:

• To investigate the role of PINK1 and parkin in regulating innate immunity and inflammation in vivo.
• To determine if mitophagy, mediated by PINK1 and parkin, restrains inflammatory responses.
• To explore the link between inflammation, mitophagy defects, and neurodegeneration in Parkinson's disease models.

Main Methods:

• Generation and analysis of Prkn-/- and Pink1-/- mice, including Prkn-/-;mutator mice with mitochondrial DNA mutations.
• Induction of inflammatory phenotypes through exhaustive exercise and mitochondrial DNA mutation.
• Assessment of inflammatory responses and rescue by genetic deletion of STING (Stimulator of Interferon Genes).
• Evaluation of dopaminergic neuron loss and motor defects in aged Prkn-/-;mutator mice and the effect of STING deletion.

Main Results:

• Prkn-/- and Pink1-/- mice exhibit significant inflammatory phenotypes following exhaustive exercise or in the presence of mitochondrial DNA mutations.
• Inflammation induced by exercise or mitochondrial DNA damage is completely resolved in mice lacking STING.
• Loss of STING also rescues dopaminergic neuron loss and motor deficits in aged Prkn-/-;mutator mice, indicating inflammation's role in these PD-relevant phenotypes.
• Elevated cytokines are observed in human patients with PRKN mutations.

Conclusions:

• PINK1 and parkin, through mitophagy, play a crucial role in restraining innate immune responses.
• Mitochondrial dysfunction and subsequent inflammation, regulated by STING, contribute to neurodegeneration in Parkinson's disease models.
• These findings highlight a critical link between mitochondrial quality control, inflammation, and the pathogenesis of Parkinson's disease.