Mitochondrial peroxiredoxin-5 as potential modulator of mitochondria-ER crosstalk in MPP+-induced cell death

Area of Science:

• Cell Biology
• Neuroscience
• Biochemistry

Background:

• Peroxiredoxin-5 (PRDX5) is an antioxidant enzyme with broad subcellular distribution, particularly in mitochondria.
• Mitochondrial PRDX5 offers cytoprotection against oxidative stress.
• Mitochondrial dysfunction and disrupted calcium (Ca²⁺) homeostasis are linked to neurodegeneration, with endoplasmic reticulum (ER) involvement in Ca²⁺ regulation.

Purpose of the Study:

• To investigate the role of mitochondrial PRDX5 in protecting SH-SY5Y cells against 1-methyl-4-phenylpyridinium (MPP⁺)-induced cell death.
• To elucidate the mechanisms by which PRDX5 influences MPP⁺-induced apoptosis and Ca²⁺ homeostasis.

Main Methods:

• Overexpression of mitochondrial PRDX5 in SH-SY5Y neuroblastoma cells.
• Induction of cell death using MPP⁺.
• Assessment of apoptosis markers (caspase-9 activation, mitochondrial DNA damage).
• Measurement of intracellular Ca²⁺ levels.
• Analysis of calpain activation and Bax cleavage.
• Use of Ca²⁺ channel inhibitors (Nimodipine, Dantrolene, 2-APB) to identify Ca²⁺ release sources.

Main Results:

• Mitochondrial PRDX5 overexpression prevented MPP⁺-induced mitochondria-dependent apoptosis, including caspase-9 activation and mitochondrial DNA damage.
• PRDX5 overexpression inhibited the rise in intracellular Ca²⁺, Ca²⁺-dependent calpain activation, and Bax cleavage.
• Ca²⁺ release was primarily identified to originate from ER stores via 1,4,5-inositol-trisphosphate receptors (IP3 R).

Conclusions:

• Mitochondrial PRDX5 plays a crucial role in protecting against MPP⁺-induced apoptosis.
• PRDX5 regulates MPP⁺-induced cell death by modulating intracellular Ca²⁺ homeostasis, potentially involving redox mechanisms affecting ER-mitochondria crosstalk.
• These findings highlight PRDX5 as a potential therapeutic target for neurodegenerative diseases involving oxidative stress and calcium dysregulation.