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Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
SIRT3 expression alleviates microglia activation‑induced dopaminergic neuron injury through the mitochondrial pathway
De-Qi Jiang1, Qing-Min Zang1, Li-Lin Jiang1
1College of Biology and Pharmacy, Guangxi Key Laboratory of Agricultural Resources Chemistry and Biotechnology, Yulin Normal University, Yulin, Guangxi Zhuang Autonomous Region 537000, P.R. China.
Abstract:
The mitochondrial protein sirtuin 3 (SIRT3) can counteract cell damage caused by oxidative stress and inflammation, and contribute to cell survival primarily by improving mitochondrial function. However, the effects of SIRT3 in dopaminergic neuronal cells (DACs) remain unclear. In our previous studies, microglia activation-associated cytotoxicity was observed to promote the apoptosis of DACs, along with the decrease of SIRT3 expression. The aim of the present study was to explore the potential neuroprotective effect of SIRT3 expression against dopaminergic neuron injury caused by microglia activation, and clarify its possible mechanisms. SIRT3 overexpression in DACs reduced the production of intracellular reactive oxygen species (ROS), cell apoptosis rate, mitochondrial membrane potential (ΔΨm) depolarization, opening of mitochondrial permeability transition pore (mPTP) and cyclophilin D (CypD) protein level, and promoted cell cycle progression. However, SIRT3 siRNA-mediated knockdown further aggravated microglia activation-mediated cytotoxicity, including ROS accumulation, increased cell apoptosis and mPTP opening, elevated the CypD level, enhanced mitochondrial ΔΨm depolarization, concomitant to cell cycle arrest at G0/G1 phase. The mechanisms of SIRT3 mitigated microglia activation-induced DAC dysfunction, which included decreased mPTP opening and Bax/Bcl-2 ratio, inhibition of mitochondrial cytochrome c release to the cytoplasm, reduced caspase-3/9 activity, increased LC3II/LC3I and beclin-1 protein expression levels, and decreased nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain-containing protein 3 (NLRP3), caspase-1, IL-1β and IL-18 protein expression. In conclusion, these results indicated that SIRT3 expression attenuated cell damage caused by microglia activation through the mitochondrial apoptosis pathway in DACs. The mitophagy-NLRP3 inflammasome pathway may also be associated with this neuroprotection. These findings may provide new intervention targets for the survival of dopaminergic neurons and the prevention and treatment of Parkinson's disease.
Insights
Sirtuin 3 (SIRT3) protects dopaminergic neurons from microglia-induced damage by improving mitochondrial function and reducing inflammation. Upregulating SIRT3 offers a potential therapeutic strategy for neurodegenerative diseases like Parkinson's.
Area of Science:
- Neuroscience
- Cell Biology
- Mitochondrial Biology
Background:
- Microglia activation contributes to dopaminergic neuronal cell death.
- Sirtuin 3 (SIRT3) is a mitochondrial protein involved in cellular protection.
- The role of SIRT3 in dopaminergic neuronal cells (DACs) under inflammatory conditions is not well understood.
Purpose of the Study:
- To investigate the neuroprotective effects of SIRT3 against microglia activation-induced injury in DACs.
- To elucidate the underlying molecular mechanisms of SIRT3-mediated neuroprotection.
Main Methods:
- Overexpression and siRNA-mediated knockdown of SIRT3 in DACs.
- Assessment of reactive oxygen species (ROS) production, apoptosis rates, and mitochondrial function (membrane potential, mPTP opening).
- Analysis of key proteins involved in apoptosis (Bax, Bcl-2, caspase-3/9, cytochrome c), mitophagy (LC3II/LC3I, beclin-1), and inflammasome activation (NLRP3, caspase-1, IL-1β, IL-18).
Main Results:
- SIRT3 overexpression reduced ROS, apoptosis, mitochondrial dysfunction, and cell cycle arrest, while promoting cell cycle progression.
- SIRT3 knockdown exacerbated microglia-induced DAC injury.
- SIRT3 mitigated injury by inhibiting the mitochondrial apoptosis pathway, decreasing the Bax/Bcl-2 ratio, reducing cytochrome c release, and lowering caspase-3/9 activity.
- SIRT3 also modulated mitophagy and suppressed the NLRP3 inflammasome pathway.
Conclusions:
- SIRT3 exerts neuroprotection in DACs against microglia activation-induced damage via the mitochondrial apoptosis pathway.
- The mitophagy-NLRP3 inflammasome pathway is implicated in SIRT3's neuroprotective mechanism.
- SIRT3 represents a potential therapeutic target for dopaminergic neuron survival and Parkinson's disease treatment.
