Dataset Information

Mutual exacerbation of peroxisome proliferator-activated receptor ? coactivator 1? deregulation and ?-synuclein oligomerization.

ABSTRACT: Aggregation of ?-synuclein (?-syn) and ?-syn cytotoxicity are hallmarks of sporadic and familial Parkinson disease (PD), with accumulating evidence that prefibrillar oligomers and protofibrils are the pathogenic species in PD and related synucleinopathies. Peroxisome proliferator-activated receptor ? coactivator 1? (PGC-1?), a key regulator of mitochondrial biogenesis and cellular energy metabolism, has recently been associated with the pathophysiology of PD. Despite extensive effort on studying the function of PGC-1? in mitochondria, no studies have addressed whether PGC-1? directly influences oligomerization of ?-syn or whether ?-syn oligomers impact PGC-1? expression.We tested whether pharmacological or genetic activation of PGC-1? or PGC-11? knockdown could modulate the oligomerization of ?-syn in vitro by using an ?-syn -fragment complementation assay.In this study, we found that both PGC-1? reference gene (RG-PGC-1?) and the central nervous system (CNS)-specific PGC-1? (CNS-PGC-1?) are downregulated in human PD brain, in A30P ?-syn transgenic animals, and in a cell culture model for ?-syn oligomerization. Importantly, downregulation of both RG-PGC-1? and CNS-PGC-1? in cell culture or neurons from RG-PGC-1?-deficient mice leads to a strong induction of ?-syn oligomerization and toxicity. In contrast, pharmacological activation or genetic overexpression of RG-PGC-1? reduced ?-syn oligomerization and rescued ?-syn-mediated toxicity.Based on our results, we propose that PGC-1? downregulation and ?-syn oligomerization form a vicious circle, thereby influencing and/or potentiating each other. Our data indicate that restoration of PGC-1? is a promising approach for development of effective drugs for the treatment of PD and related synucleinopathies.

SUBMITTER: Eschbach J

PROVIDER: S-EPMC4293280 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Mutual exacerbation of peroxisome proliferator-activated receptor γ coactivator 1α deregulation and α-synuclein oligomerization.

Eschbach Judith J von Einem Björn B Müller Kathrin K Bayer Hanna H Scheffold Annika A Morrison Bradley E BE Rudolph K Lenhard KL Thal Dietmar R DR Witting Anke A Weydt Patrick P Otto Markus M Fauler Michael M Liss Birgit B McLean Pamela J PJ Spada Albert R La AR Ludolph Albert C AC Weishaupt Jochen H JH Danzer Karin M KM

Annals of neurology 20141219 1

<h4>Objective</h4>Aggregation of α-synuclein (α-syn) and α-syn cytotoxicity are hallmarks of sporadic and familial Parkinson disease (PD), with accumulating evidence that prefibrillar oligomers and protofibrils are the pathogenic species in PD and related synucleinopathies. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a key regulator of mitochondrial biogenesis and cellular energy metabolism, has recently been associated with the pathophysiology of PD. Despite extensive ...[more]

PMID: 25363075

Similar Datasets

Project description:ObjectiveThe etiology of chondrocyte mitochondrial dysfunction in osteoarthritis (OA) is not completely understood. OA chondrocytes are deficient in the metabolic biosensors active AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT-1), which modulate the mitochondrial biogenesis "master regulator" peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α). Moreover, PGC-1α critically mediates AMPK anticatabolic activity in chondrocytes. The aim of this study was to test the hypothesis that mitochondrial biogenesis is deficient in human OA chondrocytes and that this deficiency functionally increases chondrocyte procatabolic responses, which are reversed by activation of the AMPK/SIRT-1/PGC-1α pathway.MethodsWe assessed the expression and activity (phosphorylation) of AMPKα, SIRT-1, and PGC-1α in human knee chondrocytes and human and mouse knee cartilage, and we defined and compared the content and function of mitochondria, including oxidative phosphorylation and expression of mitochondrial biogenesis factors (mitochondrial transcriptional factor A [TFAM] and nuclear respiratory factors [NRFs]).ResultsHuman knee OA chondrocytes had a decreased mitochondrial biogenesis capacity, which was linked to reduced AMPKα activity and decreased expression of SIRT-1, PGC-1α, TFAM, NRF-1, and NRF-2. Human knee OA and aging mouse knee cartilage had decreased expression of TFAM and ubiquinol-cytochrome c reductase core protein, a subunit of mitochondrial complex III, in situ. Chondrocyte TFAM knockdown inhibited mitochondrial biogenesis and enhanced procatabolic responses to interleukin-1β. Finally, activation of AMPK by A-769662 increased PGC-1α expression via SIRT-1 and reversed impairments in mitochondrial biogenesis, oxidative phosphorylation, and intracellular ATP in human knee OA chondrocytes.ConclusionMitochondrial biogenesis is deficient in human OA chondrocytes, and this deficiency promotes chondrocyte procatabolic responses. TFAM-mediated activation of the AMPK/SIRT-1/PGC-1α pathway reverses these effects, suggesting translational potential of pharmacologic AMPK activators to limit OA progression.

Project description:BackgroundDespite advances in diagnosing and treating chronic heart failure (HF), the underlying mechanisms in different HF phenotypes remain unclear. Mitochondrial energy metabolism is crucial in HF etiology. Our study aimed to explore the value of metabolic-associated biomarker peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) in identifying different HF phenotypes.MethodsA total of 172 participants were enrolled in the Affiliated Hospital of Xuzhou Medical University and were subsequently divided into four groups based on the European Society of Cardiology HF management guideline: the non-HF control (Control, N = 46), heart failure with reduced ejection fraction (HFrEF, N = 54), heart failure with mildly reduced ejection fraction (HFmrEF, N = 22), and heart failure with preserved ejection fraction (HFpEF, N = 50) groups. Each participant's baseline data were recorded, blood samples were taken, and echocardiography was conducted. The level of PGC1α expression was determined using an enzyme-linked immunosorbent assay (ELISA) kit. The receiver operative characteristics (ROC) curve was further established in the four groups to assess the diagnostic value for overall HF and each HF phenotype with the calculation of the area under the curve (AUC) and 95% confidence interval (CI).ResultsPGC1α expression was significantly increased in HF patients (315.0 ± 69.58 nmol/L) compared to non-HF participants (233.3 ± 32.69 nmol/L). Considering different HF phenotypes, PGC1α expression was considerably higher in the HFmrEF group (401.6 ± 45.1 nmol/L)than in the other two phenotypes (299.5 ± 62.27 nmol/L for HFrEF and 293.5 ± 56.37 nmol/L for HFpEF, respectively).Furthermore, the AUCs of PGC1α in overall HF and each HF phenotype were all over 0.8, showing the ideal diagnostic value. Additionally, we provided the cut-off criteria for clinical use, which needs further validation. There was no significant correlation between PGC1α and N-terminal (NT)-prohormone B-type natriuretic peptide (BNP)/blood glucose, suggesting that PGC1α might exert a unique function in HF yet in a different pattern.ConclusionWe discovered that PGC1α could be used as a potential biomarker for differentiating HF patients from those without HF and for distinguishing HFmrEF from HFrEF and HFpEF.

Project description:PGC-1a is a transcriptional coactivator known to regulate a broad gene program of nutrient and mitochondrial metabolism. Many splice variants of this protein have been identified, but their functions were unknown. This experiment was designed to delineate the downstream targets of two different PGC-1alpha isoforms (PGC-1a1 and PGC-1a4) in hepatocytes, and to determine whether inflammatory signaling (via TNFR activation) modulated these targets Liver is exposed to constantly changing metabolic and inflammatory environments. It must quickly sense and adapt to metabolic need while balancing resources required to protect itself from harmful inflammatory molecules. PGC-1α is a transcriptional coactivator that mediates cellular adaptation to diverse stimuli including inflammation. PGC-1α has a protective role against inflammation in several organs, including brain, heart, kidney, muscle, and liver. However, it is not known how hepatic PGC-1α integrates extracellular signals to mitigate inflammatory outcomes. PGC-1α exists as multiple, alternatively spliced variants whose expression is differentially regulated by different gene promoters. In human liver, we found that inflammatory conditions preferentially activated the alternative versus proximal PPARGC1A promoter. Gene expression analysis performed in primary mouse hepatocytes identified many shared and isoform-specific roles for PGC-1α variants during acute inflammation. PGC-1α1 primarily impacted gene programs of nutrient and mitochondrial metabolism, while TNFα treatment revealed that PGC-1α4 uniquely influenced several pathways related to innate immunity and cell death. Gain- and loss-of-function models showed that PGC-1α4 specifically attenuated apoptosis in response to TNFα or LPS, in contrast to PGC-1α1, which reduced expression of a wide inflammatory gene network. We conclude that PGC-1α variants have distinct, yet complimentary roles in hepatic responses to inflammation, with PGC-1α4 being an important mitigator of apoptosis.

Project description:Hepatic peroxisomes are essential for lipid conversions that include the formation of mature conjugated bile acids, the degradation of branched chain fatty acids, and the synthesis of docosahexaenoic acid. Through unresolved mechanisms, deletion of functional peroxisomes from mouse hepatocytes (L-Pex5(-/-) mice) causes severe structural and functional abnormalities at the inner mitochondrial membrane. We now demonstrate that the peroxisomal and mitochondrial anomalies trigger energy deficits, as shown by increased AMP/ATP and decreased NAD(+)/NADH ratios. This causes suppression of gluconeogenesis and glycogen synthesis and up-regulation of glycolysis. As a consequence, L-Pex5(-/-) mice combust more carbohydrates resulting in lower body weights despite increased food intake. The perturbation of carbohydrate metabolism does not require a long term adaptation to the absence of functional peroxisomes as similar metabolic changes were also rapidly induced by acute elimination of Pex5 via adenoviral administration of Cre. Despite its marked activation, peroxisome proliferator-activated receptor α (PPARα) was not causally involved in these metabolic perturbations, because all abnormalities still manifested when peroxisomes were eliminated in a peroxisome proliferator-activated receptor α null background. Instead, AMP-activated kinase activation was responsible for the down-regulation of glycogen synthesis and induction of glycolysis. Remarkably, PGC-1α was suppressed despite AMP-activated kinase activation, a paradigm not previously reported, and they jointly contributed to impaired gluconeogenesis. In conclusion, lack of functional peroxisomes from hepatocytes results in marked disturbances of carbohydrate homeostasis, which are consistent with adaptations to an energy deficit. Because this is primarily due to impaired mitochondrial ATP production, these L-Pex5-deficient livers can also be considered as a model for secondary mitochondrial hepatopathies.

Dataset Information

Mutual exacerbation of peroxisome proliferator-activated receptor ? coactivator 1? deregulation and ?-synuclein oligomerization.

Publications

Mutual exacerbation of peroxisome proliferator-activated receptor γ coactivator 1α deregulation and α-synuclein oligomerization.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets