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Mutations in PINK1 and Parkin result in autosomal recessive Parkinson's disease (PD). Cell culture and in vitro studies have elaborated the PINK1-dependent regulation of Parkin and defined how this dyad orchestrates the elimination of damaged mitochondria via mitophagy. PINK1 phosphorylates ubiquitin at serine 65 (Ser65) and Parkin at an equivalent Ser65 residue located within its N-terminal ubiquitin-like domain, resulting in activation; however, the physiological significance of Parkin Ser65 phosphorylation in vivo in mammals remains unknown. To address this, we generated a Parkin Ser65Ala (S65A) knock-in mouse model. We observe endogenous Parkin Ser65 phosphorylation and activation in mature primary neurons following mitochondrial depolarization and reveal this is disrupted in ParkinS65A/S65A neurons. Phenotypically, ParkinS65A/S65A mice exhibit selective motor dysfunction in the absence of any overt neurodegeneration or alterations in nigrostriatal mitophagy. The clinical relevance of our findings is substantiated by the discovery of homozygous PARKIN (PARK2) p.S65N mutations in two unrelated patients with PD. Moreover, biochemical and structural analysis demonstrates that the ParkinS65N/S65N mutant is pathogenic and cannot be activated by PINK1. Our findings highlight the central role of Parkin Ser65 phosphorylation in health and disease.

Mutations in PINK1 and Parkin result in autosomal recessive Parkinson's disease (PD). Cell culture and in vitro studies have elaborated the PINK1-dependent regulation of Parkin and defined how this dyad orchestrates the elimination of damaged mitochondria via mitophagy. PINK1 phosphorylates ubiquitin at serine 65 (Ser65) and Parkin at an equivalent Ser65 residue located within its N-terminal ubiquitin-like domain, resulting in activation; however, the physiological significance of Parkin Ser65 phosphorylation in vivo in mammals remains unknown. To address this, we generated a Parkin Ser65Ala (S65A) knock-in mouse model. We observe endogenous Parkin Ser65 phosphorylation and activation in mature primary neurons following mitochondrial depolarization and reveal this is disrupted in ParkinS65A/S65A neurons. Phenotypically, ParkinS65A/S65A mice exhibit selective motor dysfunction in the absence of any overt neurodegeneration or alterations in nigrostriatal mitophagy. The clinical relevance of our findings is substantiated by the discovery of homozygous PARKIN (PARK2) p.S65N mutations in two unrelated patients with PD. Moreover, biochemical and structural analysis demonstrates that the ParkinS65N/S65N mutant is pathogenic and cannot be activated by PINK1. Our findings highlight the central role of Parkin Ser65 phosphorylation in health and disease.

Mutations in PINK1 and Parkin result in autosomal recessive Parkinson's disease (PD). Cell culture and in vitro studies have elaborated the PINK1-dependent regulation of Parkin and defined how this dyad orchestrates the elimination of damaged mitochondria via mitophagy. PINK1 phosphorylates ubiquitin at serine 65 (Ser65) and Parkin at an equivalent Ser65 residue located within its N-terminal ubiquitin-like domain, resulting in activation; however, the physiological significance of Parkin Ser65 phosphorylation in vivo in mammals remains unknown. To address this, we generated a Parkin Ser65Ala (S65A) knock-in mouse model. We observe endogenous Parkin Ser65 phosphorylation and activation in mature primary neurons following mitochondrial depolarization and reveal this is disrupted in ParkinS65A/S65A neurons. Phenotypically, ParkinS65A/S65A mice exhibit selective motor dysfunction in the absence of any overt neurodegeneration or alterations in nigrostriatal mitophagy. The clinical relevance of our findings is substantiated by the discovery of homozygous PARKIN (PARK2) p.S65N mutations in two unrelated patients with PD. Moreover, biochemical and structural analysis demonstrates that the ParkinS65N/S65N mutant is pathogenic and cannot be activated by PINK1. Our findings highlight the central role of Parkin Ser65 phosphorylation in health and disease.

Although statins are the most prescribed class of lipid-lowering agents, adverse muscular toxicity has been reported, which can lead to the appearance of a myopathy. In the first part, we showed in Humans and animals that statins inhibit directly the mitochondrial respiratory chain, and induce the production of reactive oxygen species (ROS), that trigger apoptotic pathways in glycolytic skeletal muscles, whereas oxidative muscles are not impaired. We then showed in vitro that reductive stress can provoke mitochondrial oxidation, that could lead to an activation of mitochondrial biogenesis pathways. Moreover, the consequent increase in mitochondrial content enabled to protect cells against statin-induced apoptosis. Finally, we showed in vivo that the induction of mitochondrial biogenesis is necessary for statin tolerance in oxidative skeletal muscles. In conclusion, mitochondrial phenotype, both quantitatively and qualitatively, seems to be a key factor in the appearance of statin myopathy., Bien que les statines forment la classe d'hypolipidémiants la plus utilisée, une toxicité musculaire a été reportée, pouvant ainsi provoquer l’apparition d’une myopathie. Dans la première partie, nous avons montré chez l’Homme et l’animal que les statines inhibent directement la chaine respiratoire mitochondriale, et induisent la production de radicaux libres dérivés de l’oxygène (RLO), qui active les voies apoptotiques dans les muscles glycolytiques, alors que les muscles oxydatifs ne sont pas atteints. Nous avons ensuite montré in vitro que le stress réducteur peut engendrer une oxydation mitochondriale, pouvant conduire à une activation de la voie de biogenèse mitochondriale. De plus l’augmentation du contenu mitochondrial induite a permis de protéger les cellules contre l’apoptose induite par les statines. Enfin, nous avons montré in vivo que l’induction des voies de biogenèse mitochondriale est nécessaire à la tolérance des statines dans les muscles oxydatifs. En conclusion, le phénotype mitochondrial, tant au niveau quantitatif que qualitatif, semble être un facteur clé dans l’apparition de la myopathie aux statines.