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Parkin‐Mediated Ubiquitination of Mitofilin Mediates Dopaminergic Neuron Death in Response to PD Stressors
Author(s) -
Aliagan Abdulhafiz Imam,
Feng Yansheng,
Tombo Nathalie,
Bopassa Jean C.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.08895
Subject(s) - parkin , programmed cell death , microbiology and biotechnology , dopaminergic , pink1 , substantia nigra , mitochondrion , biology , parkinson's disease , apoptosis , neuroscience , dopamine , medicine , disease , biochemistry
Background Parkinson’s disease (PD) is a neurodegenerative disease characterized by a gradual and preferential loss of dopaminergic neurons in the substantia nigra. Mitochondrial dysfunction plays a critical role in the pathophysiology of dopaminergic neuron death induced by parkinsonian neurotoxins (PD stressors) that cause Parkinson’s disease (PD). However, the exact mitochondrial‐dependent mechanisms resulting in PD stressor‐induced dopaminergic neuron death remains elusive. The inner mitochondrial membrane (IMM) protein, Mitofilin, has been shown to play a key role of controlling and maintaining mitochondrial cristae morphology and its dysregulation has deleterious effects. Here, we investigated the role of Parkin‐Mitofilin interaction in PD stressor‐induced neuron death. Methods N27‐A dopaminergic neural cell line was used to determine the mitochondrial‐dependent mechanisms by which dopamine (Dopa) and Rotenone (Rot) induce cell death. Mitochondrial dysfunction was assessed by measuring mitochondrial membrane potential (MMP), reactive oxygen species (ROS) production as well as mitochondrial integrity. Cell death was measured by flow cytometry using Annexin V/7AAD dyes and cell viability assessed by MTT assay. Protein quantification was measured using biochemical techniques including Western blot analysis, immunoprecipitation, and confocal microscopy. Results We found that PD stressors treatment increased Parkin translocation in to mitochondria where it interacts with Mitofilin in the IMM. This interaction promotes Mitofilin degradation via ubiquitination, which was associated with reduced MMP and increased ROS production, effects that were concomitant with abnormal mitochondrial structure and increased neuron death including by apoptosis. Further, we found that Dopa treated cells did not activate mitophagy process, while Rot treated cells exhibited excessive mitophagy. In addition, overexpressing the mitochondrial deubiquitinase, USP30, attenuated cell death induced by Rot, but not Dopa, suggesting that Parkin mediates two distinctive mechanisms leading to neuron death. Conversely, we found that Dopa treatment triggered an increase in mitochondrial calpain activity, cleavage and release of AIF into the cytosol, as well as apoptosis via AIF‐PARP dependent mechanism. Conclusions Together, our study reveals a novel role for Parkin‐Mitofilin interaction in PD pathogenesis, which leads to the ubiquitination and degradation of Mitofilin. The degradation of Mitofilin results in mitochondrial structural damage and dysfunction that causes apoptosis via AIF‐PARP pathway. Support or Funding Information National Institutes of Health [R01 grant HL138093 (JCB)]; Perry and Ruby Stevens Parkinson’s Disease Center of Excellence pilot grant (JCB).