Parkin deficiency modulates NLRP3 inflammasome activation by attenuating an A20‐dependent negative feedback loop

Neuroinflammation and mitochondrial dysfunction, key mechanisms in the pathogenesis of Parkinson's disease (PD), are usually explored independently. Loss‐of‐function mutations of PARK2 and PARK6, encoding the E3 ubiquitin protein ligase Parkin and the mitochondrial serine/threonine kinase PINK1, account for a large proportion of cases of autosomal recessive early‐onset PD. PINK1 and Parkin regulate mitochondrial quality control and have been linked to the modulation of innate immunity pathways. We report here an exacerbation of NLRP3 inflammasome activation by specific inducers in microglia and bone marrow‐derived macrophages from Park2^?/? and Pink1^?/? mice. The caspase 1‐dependent release of IL‐1β and IL‐18 was, therefore, enhanced in Park2^?/? and Pink1^?/? cells. This defect was confirmed in blood‐derived macrophages from patients with PARK2 mutations and was reversed by MCC950, which specifically inhibits NLRP3 inflammasome complex formation. Enhanced NLRP3 signaling in Parkin‐deficient cells was accompanied by a lack of induction of A20, a well‐known negative regulator of the NF‐κB pathway recently shown to attenuate NLRP3 inflammasome activity. We also found an inverse correlation between A20 abundance and IL‐1β release, in human macrophages challenged with NLRP3 inflammasome inducers. Overall, our observations suggest that the A20/NLRP3‐inflammasome axis participates in the pathogenesis of PARK2‐linked PD, paving the way for the exploration of its potential as a biomarker and treatment target.     

Mechanisms and roles of mitophagy in neurodegenerative diseases

Mitochondria are double‐membrane‐encircled organelles existing in most eukaryotic cells and playing important roles in energy production, metabolism, Ca²⁺ buffering, and cell signaling. Mitophagy is the selective degradation of mitochondria by autophagy. Mitophagy can effectively remove damaged or stressed mitochondria, which is essential for cellular health. Thanks to the implementation of genetics, cell biology, and proteomics approaches, we are beginning to understand the mechanisms of mitophagy, including the roles of ubiquitin‐dependent and receptor‐dependent signals on damaged mitochondria in triggering mitophagy. Mitochondrial dysfunction and defective mitophagy have been broadly associated with neurodegenerative diseases. This review is aimed at summarizing the mechanisms of mitophagy in higher organisms and the roles of mitophagy in the pathogenesis of neurodegenerative diseases. Although many studies have been devoted to elucidating the mitophagy process, a deeper understanding of the mechanisms leading to mitophagy defects in neurodegenerative diseases is required for the development of new therapeutic interventions, taking into account the multifactorial nature of diseases and the phenotypic heterogeneity of patients.     

Parkin is ubiquitinated by Nrdp1 and abrogates Nrdp1-induced oxidative stress

Parkin plays an important role in the pathogenesis of Parkinson's disease. We previously described that Nrdp1, a RING-finger ubiquitin E3 ligase, interacted with Parkin by the yeast two-hybrid assay and by co-immunoprecipitation. Here we further demonstrated that overexpression of Nrdp1 significantly reduced the endogenous Parkin level in an Nrdp1 dosage-dependent and proteasome-dependent manner. More importantly, Nrdp1 ubiquitinated Parkin and catalyzed the poly-ubiquitin chains on Parkin in vitro as well as in cells, indicating Parkin is an Nrdp1 substrate. In addition, we demonstrated that overexpression of Nrdp1 increased the production of reactive oxygen species (ROS), which was abrogated by co-expression of Parkin. Conversely, suppression of Nrdp1 by shRNA conferred SH-SY5Y cells a lower ROS level. Together, we provided evidence that interactions between Nrdp1 and Parkin negatively regulated Parkin level and affected ROS production, suggesting that Nrdp1 may play a role in Parkinson's disease.     

Protective effects of Buyinqianzheng Formula on mitochondrial morphology by PINK1/Parkin pathway in SH-SY5Y cells induced by MPP+

ObjectiveBuyinqianzheng Formula (BYQZF) is clinically employed in traditional Chinese medicine to treat Parkinson’s disease (PD) by improving mitochondrial dysfunction. However, the underlying mechanisms by which BYQZF affects mitochondrial morphology remain unknown. Therefore, we observed the effects of BYQZF on mitochondria from the perspective of the PINK1/Parkin pathway.MethodsCell survival rates were assessed by Cell Counting Kit-8 assay. Expression levels of PINK1 and Parkin mRNA were examined by qRT-PCR. Protein expression levels of PINK1, PINK1-Ser228, Parkin, Parkin-Ser65, Drp1, and Drp1-Ser637 were examined by western blotting. PINK1, Parkin, and MitoTracker® Red CMXRos (MTR) were stained by triple-labeled immunofluorescence, and observed under laser confocal microscopy.ResultsCell survival rate, mitochondrial form factor, mean length and number of mitochondrial network branches, mitochondrial activity, mRNA expression levels of PINK1 and Parkin, and protein expression levels of PINK1, Parkin, and Drp1-Ser637 were reduced after 1-methyl-4-phenylpyridinium (MPP⁺) intervention. In contrast, Pearson’s correlation coefficients between PINK1 and Parkin, and between Parkin and MTR, as well as protein expression levels of PINK1-Ser228, Parkin-Ser65, and Drp1 increased significantly after MPP⁺ intervention. Treatment with BYQZF increased cell survival rate, mitochondrial form factor, mean length and number of mitochondrial network branches, mitochondrial activity, mRNA expression levels of PINK1 and Parkin, and expression of PINK1, Parkin, and Drp1-Ser637 proteins. Pearson’s correlation coefficients between PINK1 and Parkin, and between Parkin and MTR, as well as protein expression levels of PINK1-Ser228, Parkin-Ser65, and Drp1 decreased after BYQZF treatment.ConclusionThese results demonstrate that BYQZF has a protective effect on mitochondrial molecular mechanisms in the PD cell model, and the mechanism is related to the PINK1/Parkin pathway.     

野生型Parkin基因对肝癌细胞生长的影响

目的 探讨野生型及突变型Parkin基因表达对人肝癌细胞株Huh-7在体内外生长情况的影响.方法 利用脂质体介导的基因转染法将野生型及突变型Parkin基因真核表达载体转染肝癌细胞株Huh-7,筛选稳定表达细胞株,通过逆转录-聚合酶链反应(RT-PCR)进行鉴定并送测序分析.细胞增殖实验和裸鼠致瘤性实验检测各稳定表达株的体内外生长情况.结果 成功建立了稳定表达野生型和突变型Parkin基因的Huh-7细胞株.以转染空载体的Huh-7细胞作为对照,野生型Parkin基因的表达可明显抑制肝癌细胞在体外的生长(t=3.875,P=0.031),可显著减缓裸鼠皮下瘤的生长速度并减小其体积(t=8.228,P=0.003).突变型Parkin基因的表达对肝癌细胞的生长影响不大(P＞0.05).结论 野生型Parkin的重表达有助于肝癌细胞恶性表型的逆转.野生型Parkin基因是一个肝癌相关的抑癌基因.     

Parkin蛋白在鼻咽癌中表达及临床意义

目的 研究Parkin蛋白在鼻咽癌中表达及临床意义.方法 运用Elivision TM S-P免疫组化技术的方法检测54例鼻咽癌组织和16例正常鼻咽上皮组织Parkin蛋白表达水平,分析Parkin蛋白表达与鼻咽癌患者临床病理特征关系.结果 54例鼻咽癌组织Parkin蛋白表达水平为“-”23例,“＋”12例,“＋＋”7例,“＋＋＋”12例,16例正常鼻咽上皮组织Parkin蛋白表达水平为“-”0例,“＋”0例,“＋＋”3例,“＋＋＋”13例,鼻咽癌组织Parkin蛋白表达明显降低（P＜0.05）,Parkin蛋白表达与患者年龄、性别、T分期、TNM分期、病理类型无明显关系（P＞0.05）,而与淋巴结转移有关（P＜0.05）.结论 Parkin基因在鼻咽癌的发生发展中起抑癌基因作用,Parkin蛋白表达可作为判断鼻咽癌临床预后预测指标.     

Parkin mutation and deep brain stimulation outcome

Patients with parkin mutations are expected to be good candidates for deep brain stimulation (DBS) because of an excellent levodopa response and frequent occurrence of levodopa-induced dyskinesia. However, there are insufficient data on surgical outcome in patients with parkin mutations. This study aimed to compare the outcome of subthalamic nucleus DBS in patients with early-onset Parkinson’s disease with and without parkin mutations. Fourteen patients with early-onset Parkinson’s disease who underwent bilateral subthalamic nucleus DBS surgery were screened for parkin mutations and assessed for surgical outcomes at baseline and 2–5 years after surgery. Three patients had homozygote/compound heterozygote mutations; two had single heterozygote mutations; and nine had no mutations. Patients with homozygote/compound heterozygote mutations were younger at disease onset and had longer disease duration than patients without a parkin mutation. Postoperatively, there were no significant differences in improvement on the Unified Parkinson’s Disease Rating Scale part II, III, and IV, or the reduction of levodopa equivalent daily doses between patients with and without parkin mutations. The therapeutic effect of DBS did not differ between patients with and without parkin mutations.     

Minocycline protects,rescues and prevents knockdown transgenic parkin Drosophila against paraquat/iron toxicity: Implications for autosomic recessive juvenile parkinsonism

Autosomal recessive Juvenile Parkinsonism (AR-JP) is a chronic, progressive neurodegenerative disorder caused by mutation in the PARKIN gene, and invariably associated with dopaminergic (DAergic) neuronal loss and brain iron accumulation. Since current medical therapy is symptomatic and lacks significant disease-modifying effects, other treatment approaches are urgently needed it. In the present work, we investigate the role of minocycline (MC) in paraquat (PQ)/iron-induced neurotoxicity in the Drosophila TH > parkin-RNAi/+ (w[*]; UAS-parkin-RNAi; TH-GAL4) fly and have shown the following: (i) MC increased life span and restored the locomotor activity of knockdown (KD) transgenic parkin flies in comparison with the control (vehicle) group; (ii) MC at low (0.1 and 0.3 mM) and middle (0.5 mM) concentrations protected, rescued and prevented KD parkin Drosophila against PQ toxicity. However, MC at high (1 mM) concentration aggravated the toxic effect of PQ; (iii) MC protected and rescued DAergic neurons against the PQ toxic effect according to tyrosine hydroxylase (TH) > green-fluorescent protein (GFP) reporter protein microscopy and anti-TH Western blotting analysis; (iv) MC protected DAergic neurons against PQ/iron toxicity; (v) MC significantly abridged lipid peroxidation (LPO) in the protection, rescue and prevention treatment in TH > parkin-RNAi/+ flies against PQ or iron alone or combined (PQ/iron)-induced neuronal oxidative stress (OS). Our results suggest that MC exerts neuroprotection against PQ/iron-induced OS in DAergic neurons most probably by the scavenging activity of reactive oxygen species (ROS), and by chelating iron. Therefore, MC might be a potential therapeutic drug to delay, revert, or prevent AR-JP.     

Determination of gestational age: Comparative accuracy of different methods

One hundred new-born infants were studied in an attempt to test the accuracy of selected methods of post-natal assessment of gestational age. The Finnstrom method using seven external characteristics was found to be relatively more accurate both in preterm and term infants. Dubowitz and Cappuro method were accurate in premature infants only. However in a limited number of post-term infants Cappuro method yielded better results. The Finnstrom method can be recommended for routine assessment of gestational age.