Expression data from PARK2 overexpression in U251 cells
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ABSTRACT: PARK2 (PARKIN) is an E3 ubiquitin ligase whose dysfunction has been associated with the progression of Parkinsonism and human malignancies, and its role in cancer remains to be explored. In this study, we investigated its role in glioma. We used microarrays to detail the global programme of gene expression upon PARK2 overexpression in U251 cells
Project description:PARK2 (PARKIN) is an E3 ubiquitin ligase whose dysfunction has been associated with the progression of Parkinsonism and human malignancies, and its role in cancer remains to be explored. In this study, we investigated its role in glioma. We used microarrays to detail the global programme of gene expression upon PARK2 overexpression in U251 cells U251 cells with PARK2 overexpression or control (GFP) were subjected for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Parkinson's disease (PD) is a neurodegenerative pathology caused by progressive loss of dopaminergic neurons in the substantia nigra. Juvenile PD is known to be strongly associated with mutations in the PARK2 gene encoding E3 ubiquitin ligase Parkin. Despite numerous studies, molecular mechanisms that trigger PD still remain unknown. Here, we presented the transcriptome profile for neural progenitors (NP) which were obtained from iPSCs of Parkinson's disease patient, transduced with lentiviral particles carrying the full-length copy of cDNA PARK2. Transcriptome profiles were generated on an NextSeq 500 System (Illumina). A comparative transcriptome analysis of this data along with transcriptome profiles for NP of healthy donors and other patients with PD will allow determining the contribution of mutations of the PARK2 gene to PD pathogenesis and identifying genes whose expression depends on PARK2 overexpression.
Project description:Parkin, an E3 ubiquitin ligase, plays an essential role in mitochondrial quality control. However, the mechanisms by which Parkin connects mitochondrial homeostasis to cellular metabolism in adipose tissue remain unclear. Here, we demonstrate that Park2 gene (encodes Parkin) deletion specifically from adipose tissue protects mice against high-fat diet and aging-induced obesity. Despite a mild reduction in mitophagy, mitochondrial DNA (mtDNA) content and mitochondrial function are significantly increased in Park2 deficient white adipocytes. Moreover, Park2 gene deletion robustly elevates mitochondrial biogenesis by increasing Pgc1α protein stability through mitochondrial superoxide-activated Nqo1. Both in vitro and in vivo studies show that Nqo1 overexpression elevates Pgc1α protein level and mtDNA content and enhances mitochondrial activity in mouse and human adipocytes. Taken together, our findings indicate that Parkin regulates mitochondrial homeostasis by balancing mitophagy and Pgc1α-mediated mitochondrial biogenesis in white adipocytes, suggesting a potential therapeutic target in adipocytes to combat obesity and obesity-associated disorders.
Project description: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.
Project description:Parkin is an E3 ubiquitin ligase belonging to the RING-between-RING family. Mutations in the Parkin-encoding gene PARK2 are associated with familial Parkinson’s Disease. Here, we investigate the interplay between Parkin / Parkin-S65P and the inflammatory cytokine-induced ubiquitin-like modifier FAT10.
Project description:Mitochondrial dysfunction plays a major role in the pathogenesis of sporadic Parkinson’s disease (PD) and familial PD caused by mutations in the PARK2 gene. The protein, parkin, is vital for mitochondrial function, but the lack of key PD phenotypes in PARK2 knockout (KO) rodent models has hindered investigations into parkin’s role in PD pathogenesis. Human isogenic induced pluripotent stem cell (iPSC) lines with and without PARK2 KO enable studies of the effect of parkin dysfunction in dopaminergic neuronal cultures.
Project description:Mutations in the parkin gene, which encodes a ubiquitin ligase, are a major cause of autosomal recessive parkinsonism. Interestingly, parkin also plays a role in cancer as a putative tumor suppressor. Consistent with this, the gene is frequently targeted by deletion and inactivation in human malignant tumors. Here, we show that parkin expression is dramatically reduced in glioma cells, which correlates with increased cancer mortality. We further show that restoration of parkin expression in these cells promotes their arrest at G1 phase and significantly mitigates their proliferation rate both in vitro and in vivo. Notably, the level of cyclin D1, but not cyclin E, is reduced in parkin-expressing glioma cells. Moreover, parkin expression also leads to a selective downregulation of Akt serine-473 phosphorylation and VEGF receptor levels. Supporting this, cells derived from parkin null mouse exhibit increased levels of cyclin D1, VEGF receptor and Akt phosphorylation and divide significantly faster compared to their wild type counterparts. Importantly, analysis of parkin pathway activation revealed its predictive power for survival outcome of glioma patients. Taken together, our study provides a mechanism by which parkin exerts its tumor suppressor function and a signature pathway of parkin that is of potential prognostic value. Total RNA obtained from U-87MG cells stably expressing parkin or vector alone. Replicate arrays were performed for each of the 3 vector and parkin-expressing U-87MG clones.
Project description:Mutation of the gene PARK2 is the most common cause of early-onset Parkinson's Disease (PD)1,2. PARK2 encodes a gene product with E3 ubiquitin ligase activity3. In a search for multisite tumor suppressors, we identified PARK2 as a frequently targeted gene on chromosome 6q25.2-q27 in cancer. Here, we describe inactivating somatic mutations and frequent intragenic deletions of PARK2 in human malignancies. The PARK2 mutations in cancer occur in the same domains, and sometimes, at the same residues as the germline mutations causing familial PD. Cancer-specific mutations abrogate the growth suppressive effects of PARK2. PARK2 mutations in cancer decrease the gene product's E3 ligase activity, compromising its ability to ubiquitinate cyclin E and resulting in mitotic instability. These data strongly point to PARK2 as a tumor suppressor on 6q25.2-q27. PARK2, a gene that causes neuronal dysfunction when mutated in the germline, may instead contribute to oncogenesis when altered in non-neuronal somatic cells. Human colorectal samples were profiled on Agilent 244K aCGH arrays per manufacturer's instructions. Pooled reference normal DNA was used as the reference.
Project description:Mutations in the parkin gene, which encodes a ubiquitin ligase, are a major genetic cause of parkinsonism. Interestingly, parkin also plays a role in cancer as a putative tumor suppressor, and the gene is frequently targeted by deletion and inactivation in human malignant tumors. Here, we investigated a potential tumor suppressor role for parkin in gliomas. We found that parkin expression was dramatically reduced in glioma cells. Restoration of parkin expression promoted G1 phase cell cycle arrest and mitigated the proliferation rate of glioma cells in vitro and in vivo. Notably, parkin-expressing glioma cells showed a reduction in levels of cyclin D1, but not cyclin E, and a selective downregulation of Akt serine-473 phosphorylation and VEGF receptor levels. In accordance, cells derived from a parkin null mouse model exhibited increased levels of cyclin D1, VEGF receptor and Akt phosphorylation and divided significantly faster when compared with wild type cells, with suppressionof these changes following parkin re-introduction. Clinically, analysis of parkin pathway activation was predictive for the survival outcome of glioma patients. Taken together, our study provides mechanistic insight into the tumor suppressor function of parkin in brain tumors, and suggests that measurement of parkin pathway activation may be used clinically as a prognostic tool in brain tumor patients.
Project description:Mitochondrial dysfunction plays a major role in the pathogenesis of sporadic Parkinson’s disease (PD) and familial PD caused by mutations in the PARK2 gene. The protein, parkin, is vital for mitochondrial function, but the lack of key PD phenotypes in PARK2 knockout (KO) rodent models has hindered investigations into parkin’s role in PD pathogenesis. Human isogenic induced pluripotent stem cell (iPSC) lines with and without PARK2 KO enable studies of the effect of parkin dysfunction in dopaminergic neuronal cultures.