Dataset Information

Exploring the impact of PARK2 mutations on the total and mitochondrial proteome of human skin fibroblasts

ABSTRACT: Mutations in PARK2 gene are the most frequent cause of familial forms of Parkinson’s disease (PD). This gene encodes Parkin, an E3 ubiquitin ligase involved in several cellular mechanisms, such as the mitophagic process. Mutations in this gene, which cause the loss of function of Parkin, are responsible for the accumulation of damaged mitochondria. This improper disposal may generate increased levels of ROS, lower ATP production and apoptosis activation. Given the importance of mitochondrial dysfunctions and mitophagy impairment in PD pathogenesis, the aim of the present project was to investigate both whole-cell and mitochondrial proteome alterations in human skin fibroblasts of PARK2-mutated patients. To this purpose, total and mitochondrial-enriched protein fractions from fibroblasts of five PARK2-mutated patients and five control subjects were analyzed by quantitative shotgun proteomics, in order to identify proteins specifically altered by Parkin loss. Both the network-based and the GSEA analysis of proteomics results pointed out the importance of pathways in which Rab GTPase proteins are involved. An alteration of their levels also in the mitochondrial fraction may indicate a re-localization of these GTP/GDP molecular switches, master regulators of membrane trafficking. To have a more comprehensive view of the mitochondrial alterations due to PARK2 mutations, we investigated the impact of Parkin loss on mitochondrial function and network morphology. We unveiled that the mitochondrial membrane potential was reduced in PARK2-mutated patients. Nevertheless, PINK1 did not accumulate on depolarized mitochondria. Even after the treatment with CCCP, an ionophore that triggers mitophagy, the accumulation of PINK1 was less efficient in PARK2-mutated patients than in controls derived fibroblasts. The analysis of the mitochondrial network morphology showed a filamentous network with mitochondria distributed all over the cell that was comparable between PARK2-mutated patients and control subjects. Thus, our results suggested that the network morphology was not influenced by the mitochondrial depolarization and by the lack of Parkin, revealing a possible impairment of fission and, more in general, of mitochondrial dynamics. In conclusion, the present work highlighted new molecular factors and pathways altered by PARK2 mutations. Furthermore, we obtained a definition of the mitochondrial landscape and molecular mechanisms underlying the PARK2 form of Parkinson’s disease, which will help to unravel possible biochemical pathways altered also in the sporadic form of the disease. Indeed, it is known that in sporadic cases the genetic/epigenetic background and the environment lead over time to mitochondria impairment and to the accumulation of damaged organelles.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Skin, Fibroblast

DISEASE(S): Parkinson's Disease

SUBMITTER: Federica Marini

LAB HEAD: Luisa Pieroni

PROVIDER: PXD015880 | Pride | 2020-05-11

REPOSITORIES: Pride

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			Action	DRS
	Export for Pride submission.DerivedFromSearche0bf3fb2-57d4-404c-9b6f-19d814d41123.pride.mgf.gz	Mgf
	Export for Pride submission.pride.mztab.gz	Mztab
	ExportforPridesubmission.DerivedFromSearche0bf3fb2-57d4-404c-9b6f-19d814d41123.mgf	Mgf
	ExportforPridesubmission.mzid.gz	Mzid
	IC_FibroParkS10_30102017_A.raw.zip	Raw

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Publications

Exploring the Impact of <i>PARK2</i> Mutations on the Total and Mitochondrial Proteome of Human Skin Fibroblasts.

Zilocchi Mara M Colugnat Ilaria I Lualdi Marta M Meduri Monica M Marini Federica F Corasolla Carregari Victor V Moutaoufik Mohamed Taha MT Phanse Sadhna S Pieroni Luisa L Babu Mohan M Garavaglia Barbara B Fasano Mauro M Alberio Tiziana T

Frontiers in cell and developmental biology 20200611

Mutations in <i>PARK2</i> gene are the most frequent cause of familial forms of Parkinson's disease (PD). This gene encodes Parkin, an E3 ubiquitin ligase involved in several cellular mechanisms, including mitophagy. Parkin loss-of-function is responsible for the cellular accumulation of damaged mitochondria, which in turn determines an increment of reactive oxygen species (ROS) levels, lower ATP production, and apoptosis activation. Given the importance of mitochondrial dysfunction and mitophag ...[more]

PMID: 32596240

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Project description:Mutations in the E3 ubiquitin ligase Parkin cause autosomal recessive Parkinson’s disease. In concert with PINK1, Parkin regulates the clearance of dysfunctional mitochondria via lysosomes. In response, new mitochondria are generated through an interplay of nuclear- and mitochondrial-encoded proteins. Mouse and overexpression models suggests that Parkin also influences these processes, both in the nuclear cascade and at the level of the mitochondrial genome. Additionally, Parkin has been shown to prevent mitochondrial membrane permeation, impeding the escape of mitochondrial DNA (mtDNA). In line with this, serum from Parkin mutation carriers showed higher levels of circulating cell-free mtDNA (ccf-mtDNA) and inflammatory cytokines – a result of the innate immune response - which can be triggered by cytosolic mtDNA. However, Parkin’s relationship with the mitochondrial genome and the mitogenesis pathway has not been explored in patient-derived neurons. To investigate this aspect of Parkin’s cellular function endogenously, we generated induced pluripotent stem cell (iPSC)-derived midbrain neurons from Parkin mutation carriers and healthy controls. In Parkin-deficient cells, several factors in the mitochondrial biogenesis pathway were significantly reduced, resulting in impaired mtDNA homeostasis - a phenomenon that was exacerbated in dopaminergic neurons. Moreover, in response to a lack of freely accessible NAD+, the energy sensor Sirtuin 1, which simultaneously controls mtDNA maintenance processes and mitophagy, was downregulated in Parkin-deficient neurons. However, while impaired lysosomal degradation of mitochondria was only detectable in oxidative conditions, biogenesis defects were already apparent in untreated patient neurons. This may suggest that mitophagy disruption occurs in response to acute stress. By contrast, the biogenesis pathway may be continually impaired in Parkin-associated Parkinson’s disease. Next, using a mutagenic stress model in combination with Parkin knockdown, we detected an increase in ccf-mtDNA and the cytosolic DNA sensor cGAS. To explore if ccf-mtDNA can act as damage-associated molecular pattern in the brain, we used postmortem tissue from a Parkin mutation carrier and performed single-cell RNA sequencing. In the midbrain lacking Parkin, we found a higher percentage of microglia along with an upregulation of proinflammatory cytokines in these cells. Together, our findings suggest a role for Parkin in the control of mitochondrial biogenesis and mtDNA maintenance, which protects midbrain neurons from neuroinflammation-induced degeneration. Future research in iPSC-derived neuron-microglia co-culture systems could aim at developing PD treatment approaches that target the neuronal release or microglial uptake of ccf-mtDNA.