PARK6 PINK1 mutants are defective in maintaining mitochondrial membrane potential and inhibiting ROS formation of substantia nigra dopaminergic neurons

Department of Physiology and Pharmacology, Chang Gung University School of Medicine, Kwei-San, Tao-Yuan, Taiwan, ROC.
Biochimica et Biophysica Acta (Impact Factor: 4.66). 03/2011; 1812(6):674-84. DOI: 10.1016/j.bbadis.2011.03.007
Source: PubMed


Mutations in PTEN-induced kinase 1 (PINK1) gene cause recessive familial type 6 of Parkinson's disease (PARK6). PINK1 is believed to exert neuroprotective effect on SN dopaminergic cells by acting as a mitochondrial Ser/Thr protein kinase. Autosomal recessive inheritance indicates the involvement of loss of PINK1 function in PARK6 pathogenesis. In the present study, confocal imaging of cultured SN dopaminergic neurons prepared from PINK1 knockout mice was performed to investigate physiological importance of PINK1 in maintaining mitochondrial membrane potential (ΔΨ(m)) and mitochondrial morphology and test the hypothesis that PARK6 mutations cause the loss of PINK1 function. PINK1-deficient SN dopaminergic neurons exhibited a depolarized ΔΨ(m). In contrast to long thread-like mitochondria of wild-type neurons, fragmented mitochondria were observed from PINK1-null SN dopaminergic cells. Basal level of mitochondrial superoxide and oxidative stressor H(2)O(2)-induced ROS generation were significantly increased in PINK1-deficient dopaminergic neurons. Overexpression of wild-type PINK1 restored hyperpolarized ΔΨ(m) and thread-like mitochondrial morphology and inhibited ROS formation in PINK1-null dopaminergic cells. PARK6 mutant (G309D), (E417G) or (CΔ145) PINK1 failed to rescue mitochondrial dysfunction and inhibit oxidative stress in PINK1-deficient dopaminergic neurons. Mitochondrial toxin rotenone-induced cell death of dopaminergic neurons was augmented in PINK1-null SN neuronal culture. These results indicate that PINK1 is required for maintaining normal ΔΨ(m) and mitochondrial morphology of cultured SN dopaminergic neurons and exerts its neuroprotective effect by inhibiting ROS formation. Our study also provides the evidence that PARK6 mutant (G309D), (E417G) or (CΔ145) PINK1 is defective in regulating mitochondrial functions and attenuating ROS production of SN dopaminergic cells.

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Available from: Chin-Song Lu, Aug 11, 2014
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    • "Thedecreaseinmitochondrialmembranepotentialisnotdueto aprotonleak,buttorespiratorychaindefectslikecomplexIand complexIIIdeficiency(Amoetal.,2011,2014).Therefore,PINK1 isrequiredformaintainingnormalmitochondrialmorphology ofSNpcDAneuronsincultureandexertsitsneuroprotective effectbyinhibitingROSformation(Wangetal.,2011).Inanimal models,studiesshowthatthelackofPINK1resultedinabnormal mitochondrialmorphology,lossofSNpcDAneurons,reduction incomplexIactivity,andenhancedvulnerabilitytooxidative stress(Clarketal.,2006;Kitadaetal.,2007;Gautieretal.,2008). Thesedefectscanbeamelioratedandrescuedbytheenhanced expressionofparkin(Yangetal.,2006;Exneretal.,2007).This lastscenarioseemstoinvolvePINK1andParkininacommon pathwaythatregulatesmitochondrialphysiologyandcellsurvival inwhichPINK1seemstobefunctioningupstreamofParkin,at leastasobservedinDrosophiladiseasemodels(Clarketal.,2006). "
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    • "TMRM was excited at 543 nm with a HeNe green laser, and the emitted fluorescent signal at 560–620 nm was collected. Z-stacks of 15 confocal TMRM fluorescence images (with an acquisition interval along the z-axis of 0.3 μm) were processed and analyzed by LAS AF software (Leica) as previously described (Wang et al., 2011). Confocal MitoSox Red staining was performed to visualize mitochondrial level of superoxide anion in SH-SY5Y cells and SN dopaminergic neurons. "
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