Alpha-synuclein-induced mitochondrial dysfunction is mediated via a sirtuin 3-dependent pathway

Area of Science:

• Neuroscience
• Mitochondrial Biology
• Biochemistry

Background:

• Alpha-synuclein (αsyn) misfolding and aggregation are key features of Parkinson's disease (PD).
• Mitochondrial dysfunction, including impaired dynamics and biogenesis, is central to PD pathogenesis.
• Sirtuin 3 (SIRT3), a mitochondrial NAD+-dependent enzyme, is crucial for mitochondrial function and is downregulated in aging and neurodegenerative diseases.

Purpose of the Study:

• To investigate the association between alpha-synuclein (αsyn) and mitochondrial sirtuin 3 (SIRT3) levels in Parkinson's disease.
• To elucidate the role of SIRT3 in αsyn-induced mitochondrial dysfunction.
• To explore therapeutic strategies targeting SIRT3 for PD.

Main Methods:

• Assessed mitochondrial SIRT3 levels in cells expressing oligomeric αsyn.
• Examined mitochondrial integrity, dynamics, respiration, and stress response markers.
• Validated findings in a rodent PD model and human post-mortem Lewy body disease (LBD) brain tissue.

Main Results:

• αsyn associates with mitochondria, decreasing SIRT3 levels, mitochondrial biogenesis, and oxygen consumption rate (OCR).
• SIRT3 downregulation correlated with impaired mitochondrial dynamics (altered AMPK, CREB, DRP1 phosphorylation).
• Treatment with an AMPK agonist (AICAR) restored SIRT3, improved mitochondrial function, and reduced αsyn oligomers in a SIRT3-dependent manner.

Conclusions:

• Decreased SIRT3 levels contribute to αsyn-induced mitochondrial dysfunction in PD.
• Pharmacological enhancement of SIRT3 can counteract mitochondrial deficits and reduce αsyn pathology.
• SIRT3 plays a protective role in PD-associated pathways, offering a potential therapeutic target.