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AbstractObjectiveMethodsResultsConclusionsThis study aimed to explore the effects of Parkin (Prkn) knockout in a juvenile mouse model of asthma.Prkn knockout (KO) and wild type (WT) mice were utilized to establish a juvenile mouse asthma model. The asthma model involved exposure to hyperoxia/ovalbumin (OVA), encompassing hyperoxia from postnatal day 1 (P1) to P7, sensitization on P21 and P28, and challenge from P36 to P42. Room air/phosphate-buffered saline (PBS) served as the control condition. Following airway resistance measurement, bronchoalveolar lavage fluid (BALF) was collected for cellular analysis, and lung tissues were subjected to histological examination and oxidative stress assessment. Serum levels of ovalbumin-specific immunoglobulin E (IgE), total IgE, interleukin-4 (IL-4), IL-5, and IL-13 were quantified using enzyme-linked immunosorbent assay (ELISA).WT mice exposed to hyperoxia/OVA showed decreased body weight and increased airway resistance compared to those exposed to control condition. Conversely, KO mice exhibited increased body weight under asthma conditions. KO mice with asthma had reduced total cell counts, along with lower levels of lymphocytes, eosinophils, and neutrophils, compared to WT asthma mice. Histological assessment showed attenuated inflammation and reduced collagen deposition in KO mice relative to WT mice, with lower serum levels of inflammatory markers and improved lung oxidative stress profiles. No significant differences were observed between KO and WT mice under room air/PBS conditions.Parkin knockout in juvenile mice mitigates asthma-related alterations in airway resistance, histopathological changes, inflammation status, and oxidative stress. These findings highlight a protective role of Parkin deficiency against asthma-associated pathologies. [ABSTRACT FROM AUTHOR]

Background: High fat-fructose diet is a proinflammatory diet that increases risk of hepatocytes and myocytes steatosis and fibrosis. Finding anti-inflammatory strategies to fight these harmful effects is paid attention to nowadays. This study compared the effects of two widely anti-inflammatory interventions—metformin and intermittent fasting on myocytes and hepatocyte injury induced by proinflammatory diet and tracking possible underlying mechanisms. In this work, rats fed high fat-fructose diet were subdivided into untreated group, treated by metformin, and/or intermittent fasting. Results: Metformin (300 mg/kg/day) and intermittent fasting (3 days/week) specially their combination for 4 weeks showed significant improvement in insulin resistance, lipid profile, antioxidants (p < 0.05), as well as enhanced hepatocytes and myocytes repair and reduced collagen deposition through upregulation of mitophagy-related genes: PINK1, PARKIN, LAMP2, and PPAR-α (p < 0.05). Conclusions: Intermittent fasting has beneficial metabolic and molecular therapeutic effects against proinflammatory diet-induced injury. Their results are like those of metformin sparing its adverse effects. Their combination showed additional effects against diet-induced myocytes and hepatocyte injury by upregulation of mitophagy-related genes without the need of increasing the dose of metformin. [ABSTRACT FROM AUTHOR]

Objective: To investigate the role of Parkin overexpression-induecd mitophagy in alleviating acute lung injury of exertional heat stroke(EHS) rats. Methods: Eighty SD rats were divided into four groups: Control group (CON group), Control Parkin overexpression group (CON + Parkin group), exertional heat stroke group (EHS group), and exertional heat stroke Parkin overexpression group (EHS + Parkin group). Adeno-associated virus carrying the Parkin gene was intravenously injected into the rats to overexpress Parkin in the lung tissue. An exertional heat stroke rat model was established, and survival curves were plotted. Lung Micro-CT was performed, and lung coefficient and pulmonary microvascular permeability were measured. Enzyme-linked immunosorbent assays(ELISA) were used to determine the levels of interleukin-6(IL-6), interleukin-1β(IL-1β), Tumor necrosis factor-α(TNF-α), and reactive oxygen species(ROS). The morphology of mitochondria in type II epithelial cells of lung tissue was observed using transmission electron microscopy. The apoptosis of lung tissue, the level of mitophagy, and the co-localization of Pink1 and Parkin were determined using immunofluorescence. The expression of Pink1, Parkin, MFN2, PTEN-L, PTEN, p62, and microtubule associated protein 1 light chain 3 (LC3) in rat lung tissue was measured by western blot. Results: Compared with the CON group, there were more severe lung injury and more higher levels of IL-6, IL-1β, TNF-α in EHS rats. Both of the LC3-II/LC3-I ratio and the co-localization of LC3 and Tom20 in the lung tissue of EHS rats decreased. Compared with the EHS group, the survival rate of rats in the EHS + Parkin overexpression group was significantly increased, lung coefficient and pulmonary microvascular permeability were reduced, and pathological changes such as exudation and consolidation were significantly alleviated. The levels of IL-6, IL-1β, TNF-α, and ROS were significantly decreased; the degree of mitochondrial swelling in type II alveolar epithelial cells was reduced, and no vacuolization was observed. Lung tissue apoptosis was reduced, and the colocalization fluorescence of Pink1 and Parkin, as well as LC3 and Tom20, were increased. The expression of Parkin and LC3-II/LC3-I ratio in lung tissue were both increased, while the expression of P62, Pink1, MFN2, and PTEN-L was decreased. Conclusion: Pink1/Parkin-mediated mitophagy dysfunction is one of the mechanisms underlying acute lung injury in rats with EHS, and activation of Parkin overexpression induced-mitophagy can alleviate acute lung injury caused by EHS. [ABSTRACT FROM AUTHOR]

Dysregulated autophagy/mitophagy is one of the major causes of cardiac injury in ischemic conditions. Glycogen synthase kinase-3alpha (GSK-3α) has been shown to play a crucial role in the pathophysiology of cardiac diseases. However, the precise role of GSK-3α in cardiac mitophagy remains unknown. Herein, we investigated the role of GSK-3α in cardiac mitophagy by employing AC16 human cardiomyocytes under the condition of acute hypoxia. We observed that the gain-of-GSK-3α function profoundly induced mitophagy in the AC16 cardiomyocytes post-hypoxia. Moreover, GSK-3α overexpression led to increased ROS generation and mitochondrial dysfunction in cardiomyocytes, accompanied by enhanced mitophagy displayed by increased mt-mKeima intensity under hypoxia. Mechanistically, we identified that GSK-3α promotes mitophagy through upregulation of BNIP3, caused by GSK-3α-mediated increase in expression of HIF-1α and FOXO3a in cardiomyocytes post-hypoxia. Moreover, GSK-3α displayed a physical interaction with BNIP3 and, inhibited PINK1 and Parkin recruitment to mitochondria was observed specifically under hypoxia. Taken together, we identified a novel mechanism of mitophagy in human cardiomyocytes. GSK-3α promotes mitochondrial dysfunction and regulates FOXO3a -mediated BNIP3 overexpression in cardiomyocytes to facilitate mitophagy following hypoxia. An interaction between GSK-3α and BNIP3 suggests a role of GSK-3α in BNIP3 recruitment to the mitochondrial membrane where it enhances mitophagy in stressed cardiomyocytes independent of the PINK1/Parkin. [Display omitted] • GSK-3a promotes oxidative stress and mitochondrial dysfunction under hypoxia. • Gain-of-GSK-3α function activates hypoxia-induced mitophagy in cardiomyocytes. • GSK-3α physically interacts with BNIP3 specifically under hypoxia. • GSK-3α inhibits PINK1/Parkin recruitment to mitochondria post-hypoxia. • GSK-3α promotes hypoxia-induces mitophagy through FOXO3a-mediated BNIP3 upregulation. [ABSTRACT FROM AUTHOR]

Parkin is an E3 ubiquitin ligase implicated in early-onset forms of Parkinson's disease. It catalyzes a transthiolation reaction by accepting ubiquitin (Ub) from an E2 conjugating enzyme, forming a short-lived thioester intermediate, and transfers Ub to mitochondrial membrane substrates to signal mitophagy. A major impediment to the development of Parkinsonism therapeutics is the lack of structural and mechanistic detail for the essential, short-lived transthiolation intermediate. It is not known how Ub is recognized by the catalytic Rcat domain in parkin that enables Ub transfer from an E2~Ub conjugate to the catalytic site and the structure of the transthiolation complex is undetermined. Here, we capture the catalytic intermediate for the Rcat domain of parkin in complex with ubiquitin (Rcat-Ub) and determine its structure using NMR-based chemical shift perturbation experiments. We show that a previously unidentified a-helical region near the Rcat domain is unmasked as a recognition motif for Ub and guides the C-terminus of Ub toward the parkin catalytic site. Further, we apply a combination of guided AlphaFold modeling, chemical cross-linking, and single turnover assays to establish and validate a model of full-length parkin in complex with UbcH7, its donor Ub, and phosphoubiquitin, trapped in the process of transthiolation. Identification of this catalytic intermediate and orientation of Ub with respect to the Rcat domain provides important structural insights into Ub transfer by this E3 ligase and explains how the previously enigmatic Parkinson's pathogenic mutation T415N alters parkin activity. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate the role of Pink1/Parkin-mediated mitochondrial autophagy in exertional heat stroke-induced acute lung injury in rats. METHODS: Sixty SD rats were divided into four groups: normal group (CON group), normal Parkin overexpression group (CON + Parkin group), exertional heat stroke group (EHS group), and exertional heat stroke Parkin overexpression group (EHS + Parkin group). Adeno-associated virus carrying the Parkin gene was intravenously injected into the rats to overexpress Parkin in the lung tissue. An exertional heat stroke rat model was established, and survival curves were plotted. Lung micro-CT was performed, and lung coefficient and pulmonary microvascular permeability were measured. RESULTS: Compared with the EHS group, the survival rate of rats in the EHS + Parkin overexpression group was significantly increased, lung coefficient and pulmonary microvascular permeability were reduced, and pathological changes such as exudation and consolidation were significantly reduced. The levels of inflammatory factors IL-6, IL-1β, TNF- α, and ROS were significantly decreased; the degree of mitochondrial swelling in type II alveolar epithelial cells was reduced, and no vacuolization was observed. Lung tissue apoptosis was reduced, and the colocalization fluorescence of Pink1 and Parkin, as well as LC3 and Tom20, were increased. The expression of Parkin and LC3-II/LC3-I ratio in lung tissue were both increased, while the expression of P62, Pink1, MFN2, and PTEN-L was decreased. CONCLUSION: Impairment of Pink1/Parkin-mediated mitochondrial autophagy function is one of the mechanisms of exertional heat stroke-induced acute lung injury in rats. Activation of the Pink1/Parkin pathway can alleviate acute lung injury caused by exertional heat stroke. [ABSTRACT FROM AUTHOR]

Mitochondria are crucial for cellular ATP production. They are highly dynamic organelles, whose morphology and function are controlled through mitochondrial fusion and fission. The specific roles of mitochondria in podocytes, the highly specialized cells of the kidney glomerulus, remain less understood. Given the significant structural, functional, and molecular similarities between mammalian podocytes and Drosophila nephrocytes, we employed fly nephrocytes to explore the roles of mitochondria in cellular function. Our study revealed that alterations in the Pink1–Park (mammalian PINK1–PRKN) pathway can disrupt mitochondrial dynamics in Drosophila nephrocytes. This disruption led to either fragmented or enlarged mitochondria, both of which impaired mitochondrial function. The mitochondrial dysfunction subsequently triggered defective intracellular endocytosis, protein aggregation, and cellular damage. These findings underscore the critical roles of mitochondria in nephrocyte functionality. [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr(VI)) is a hazardous metallic compound commonly used in industrial processes. The liver, responsible for metabolism and detoxification, is the main target organ of Cr(VI). Toxicity experiments were performed to investigate the impacts of low-dose exposure to Cr(VI) on rat livers. It was revealed that exposure of 0.05 mg/kg potassium dichromate (K2Cr2O7) and 0.25 mg/kg K2Cr2O7 notably increased malondialdehyde (MDA) levels and the expressions of P-AMPK, P-ULK, PINK1, P-Parkin, and LC3II/LC3I, and significantly reduced SOD activity and P-mTOR and P62 expression levels in liver. Electron microscopy showed that CR(VI) exposure significantly increased mitophagy and the destruction of mitochondrial structure. This study simulates the respiratory exposure mode of CR(VI) workers through intratracheal instillation of CR(VI) in rats. It confirms that autophagy in hepatocytes is induced by low concentrations of CR(VI) and suggest that the liver damage caused by CR(VI) may be associated with the AMPK-related PINK/Parkin signaling pathway. [ABSTRACT FROM AUTHOR]

The prevalence of age-related neurodegenerative diseases, such as Parkinson's disease (PD) and related disorders continues to grow worldwide. Increasing evidence links intracellular inclusions of misfolded alpha-synuclein (α-syn) aggregates, so-called Lewy bodies (LB) and Lewy neuritis, to the progressive pathology of PD and other synucleinopathies. Our previous findings established that α-syn oligomers induce S-nitrosylation and deregulation of the E3-ubiquitin ligase Parkin, leading to mitochondrial disturbances in neuronal cells. The accumulation of damaged mitochondria as a consequence, together with the release of mitochondrial-derived damage-associated molecular patterns (mtDAMPs) could activate the innate immune response and induce neuroinflammation ("mito-inflammation"), eventually accelerating neurodegeneration. However, the molecular pathways that transmit pro-inflammatory signals from damaged mitochondria are not well understood. One of the proposed pathways could be the cyclic GMP-AMP synthase (cGAS) – stimulator of interferon genes (STING) (cGAS–STING) pathway, which plays a pivotal role in modulating the innate immune response. It has recently been suggested that cGAS–STING deregulation may contribute to the development of various pathological conditions. Especially, its excessive engagement may lead to neuroinflammation and appear to be essential for the development of neurodegenerative brain diseases, including PD. However, the precise molecular mechanisms underlying cGAS–STING pathway activation in PD and other synucleinopathies are not fully understood. This review focuses on linking mitochondrial dysfunction to neuroinflammation in these disorders, particularly emphasizing the role of the cGAS–STING signaling. We propose the cGAS–STING pathway as a critical driver of inflammation in α-syn-dependent neurodegeneration and hypothesize that cGAS–STING–driven "mito-inflammation" may be one of the key mechanisms promoting the neurodegeneration in PD. Understanding the molecular mechanisms of α-syn–induced cGAS–STING–associated "mito-inflammation" in PD and related synucleinopathies may contribute to the identification of new targets for the treatment of these disorders. [ABSTRACT FROM AUTHOR]

Mechanisms that prevent accidental activation of the PINK1/Parkin mitophagy circuit on healthy mitochondria are poorly understood. On the surface of damaged mitochondria, PINK1 accumulates and acts as the input signal to a positive feedback loop of Parkin recruitment, which in turn promotes mitochondrial degradation via mitophagy. However, PINK1 is also present on healthy mitochondria, where it could errantly recruit Parkin and thereby activate this positive feedback loop. Here, we explore emergent properties of the PINK1/Parkin circuit by quantifying the relationship between mitochondrial PINK1 concentrations and Parkin recruitment dynamics. We find that Parkin is recruited to mitochondria only if PINK1 levels exceed a threshold and then only after a delay that is inversely proportional to PINK1 levels. Furthermore, these two regulatory properties arise from the input-coupled positive feedback topology of the PINK1/Parkin circuit. These results outline an intrinsic mechanism by which the PINK1/Parkin circuit can avoid errant activation on healthy mitochondria.

Abstract Background High fat-fructose diet is a proinflammatory diet that increases risk of hepatocytes and myocytes steatosis and fibrosis. Finding anti-inflammatory strategies to fight these harmful effects is paid attention to nowadays. This study compared the effects of two widely anti-inflammatory interventions—metformin and intermittent fasting on myocytes and hepatocyte injury induced by proinflammatory diet and tracking possible underlying mechanisms. In this work, rats fed high fat-fructose diet were subdivided into untreated group, treated by metformin, and/or intermittent fasting. Results Metformin (300 mg/kg/day) and intermittent fasting (3 days/week) specially their combination for 4 weeks showed significant improvement in insulin resistance, lipid profile, antioxidants (p

Abstract Objective To investigate the role of Parkin overexpression-induecd mitophagy in alleviating acute lung injury of exertional heat stroke(EHS) rats. Methods Eighty SD rats were divided into four groups: Control group (CON group), Control Parkin overexpression group (CON + Parkin group), exertional heat stroke group (EHS group), and exertional heat stroke Parkin overexpression group (EHS + Parkin group). Adeno-associated virus carrying the Parkin gene was intravenously injected into the rats to overexpress Parkin in the lung tissue. An exertional heat stroke rat model was established, and survival curves were plotted. Lung Micro-CT was performed, and lung coefficient and pulmonary microvascular permeability were measured. Enzyme-linked immunosorbent assays(ELISA) were used to determine the levels of interleukin-6(IL-6), interleukin-1β(IL-1β), Tumor necrosis factor-α(TNF-α), and reactive oxygen species(ROS). The morphology of mitochondria in type II epithelial cells of lung tissue was observed using transmission electron microscopy. The apoptosis of lung tissue, the level of mitophagy, and the co-localization of Pink1 and Parkin were determined using immunofluorescence. The expression of Pink1, Parkin, MFN2, PTEN-L, PTEN, p62, and microtubule associated protein 1 light chain 3 (LC3) in rat lung tissue was measured by western blot. Results Compared with the CON group, there were more severe lung injury and more higher levels of IL-6, IL-1β, TNF-α in EHS rats. Both of the LC3-II/LC3-I ratio and the co-localization of LC3 and Tom20 in the lung tissue of EHS rats decreased. Compared with the EHS group, the survival rate of rats in the EHS + Parkin overexpression group was significantly increased, lung coefficient and pulmonary microvascular permeability were reduced, and pathological changes such as exudation and consolidation were significantly alleviated. The levels of IL-6, IL-1β, TNF-α, and ROS were significantly decreased; the degree of mitochondrial swelling in type II alveolar epithelial cells was reduced, and no vacuolization was observed. Lung tissue apoptosis was reduced, and the colocalization fluorescence of Pink1 and Parkin, as well as LC3 and Tom20, were increased. The expression of Parkin and LC3-II/LC3-I ratio in lung tissue were both increased, while the expression of P62, Pink1, MFN2, and PTEN-L was decreased. Conclusion Pink1/Parkin-mediated mitophagy dysfunction is one of the mechanisms underlying acute lung injury in rats with EHS, and activation of Parkin overexpression induced-mitophagy can alleviate acute lung injury caused by EHS.

BACKGROUND: The activation of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome has been found to be an important factor in the pathogenesis of gouty arthritis, and the activation of NLPR3 inflammasome can be effectively inhibited by regulating the PTEN-induced kinas 1 (PINK1)/Parkin signaling pathway. OBJECTIVE: To investigate the effect of Duhuo Jisheng Decoction on the PINK1/Parkin/NLRP3 signaling pathway. METHODS: (1) Animal experiment: Male Sprague-Dawley rats were randomly divided into control group, model group, positive control group (Qiushuixian tablets 0.3 mg/kg), and low-, medium-, and high-dose Duhuo Jisheng Decoction groups (6.9, 13.8, and 27.6 g/kg, respectively). A rat gouty arthritis model was constructed by injecting monosodium urate crystal suspension into the right hind ankle joint cavity of rats in all the groups except for the control group. (2) Cell experiment: Human monocytes (THP-1) were divided into blank control group, model group, Duhuo Jisheng Decoction-containing serum group, and PINK1 siRNA+Duhuo Jisheng Decoction-containing serum group. The cells in each group except the blank control group were stimulated with sodium urate to establish an in vitro gouty arthritis model. (3) The swelling degree, joint circumference, gait score, joint inflammation index and degree of pathological grading in the ankle joints of rats were observed. Enzyme-linked immunosorbent assay was used to detect the levels of uric acid, C-reactive protein, NLRP3, and interleukin 1β. Immunoblotting assay was used to detect the levels of proteins related to the PINK1/Parkin/NLRP3 pathway. Tetramethyl azolidine blue assay was used to detect cell activity. Immunofluorescent double staining was performed to detect the level of mitophagy. Immunofluorescence was used to detect the expression of NLRP3 and interleukin 1β. RESULTS AND CONCLUSION: (1) Compared with the control group, rats in the model group showed elevated ankle swelling and ankle circumference at 6-48 hours (P < 0.05), elevated gait scores and joint inflammation indexes at 24 and 48 hours (P < 0.05), elevated serum uric acid and C-reactive protein levels, degree of pathological classification, expression of PINK1, Parkin, and NLRP3 proteins, and interleukin 1β level in synovial tissues (P < 0.05). Compared with the model group, the protein expression levels of PINK1 and Parkin in all the Duhuo Jisheng Decoction groups were elevated, while the levels of the other indexes were decreased (P < 0.05). (2) Compared with the model group, NLRP3 activity, interleukin 1β level and mitochondrial outer membrane translocator protein 20 protein level in the Duhuo Jisheng Decoction-containing serum group were decreased (P < 0.05), while the proliferation inhibition rate, PINK1, Parkin and LC3B protein level were increased (P < 0.05). Compared with the model group, the mitochondrial autophagy level of cells in the Duhuo Jisheng Decoction-containing serum group was elevated (P < 0.05), while NLRP3 and interleukin 1β protein levels were decreased (P < 0.05). (3) Compared with the Duhuo Jisheng Decoction-containing serum group, the mitochondrial autophagy level of cells in the PINK1 siRNA+Duhuo Jisheng Decoction-containing serum group was decreased (P < 0.05), and the expression levels of NLRP3 and interleukin 1β were elevated (P < 0.05). To conclude, Duhuo Jisheng Decoction inhibits the activation of NLRP3 inflammasome by regulating the PINK1/Parkin signaling pathway, thereby exerting a therapeutic effect on gouty arthritis. [ABSTRACT FROM AUTHOR]

Abstract Background Diabetic sarcopenia is a disease‐related skeletal muscle disorder that causes progressive symptoms. The complete understanding of its pathogenesis is yet to be unravelled, which makes it difficult to develop effective therapeutic strategies. This study investigates how MFG‐E8 affects mitophagy and the protective role of D‐pinitol (DP) in diabetic sarcopenia. Methods In vivo, streptozotocin‐induced diabetic SAM‐R1 (STZ‐R1) and SAM‐P8 (STZ‐P8) mice (16‐week‐old) were used, and STZ‐P8 mice were administrated of DP (150 mg/kg per day) for 6 weeks. Gastrocnemius muscles were harvested for histological analysis including transmission electron microscopy. Proteins were evaluated via immunohistochemistry (IHC), immunofluorescence (IF), and western blotting (WB) assay. In vitro, advanced glycation end products (AGEs) induced diabetic and D‐galactose (DG) induced senescent C2C12 models were established and received DP, MFG‐E8 plasmid (Mover)/siRNA (MsiRNA), or 3‐MA/Torin‐1 intervention. Proteins were evaluated by IF and WB assay. Immunoprecipitation (IP) and co‐immunoprecipitation (CO‐IP) were used for hunting the interacted proteins of MFG‐E8. Results In vivo, sarcopenia, mitophagy deficiency, and up‐regulated MFG‐E8 were confirmed in the STZ‐P8 group. DP exerted protective effects on sarcopenia and mitophagy (DP + STZ‐P8 vs. STZ‐P8; all P

Mitochondrial quality control is essential in mitochondrial function. To examine the importance of Parkin-dependent mechanisms in mitochondrial quality control, we assessed the impact of modulating Parkin on proteome flux and mitochondrial function in a context of reduced mtDNA fidelity. To accomplish this, we crossed either the Parkin knockout mouse or ParkinW402A knock-in mouse lines to the Polg mitochondrial mutator line to generate homozygous double mutants. In vivo longitudinal isotopic metabolic labeling was followed by isolation of liver mitochondria and synaptic terminals from the brain, which are rich in mitochondria. Mass spectrometry and bioenergetics analysis were assessed. We demonstrate that slower mitochondrial protein turnover is associated with loss of mtDNA fidelity in liver mitochondria but not synaptic terminals, and bioenergetic function in both tissues is impaired. Pathway analysis revealed loss of mtDNA fidelity is associated with disturbances of key metabolic pathways, consistent with its association with metabolic disorders and neurodegeneration. Furthermore, we find that loss of Parkin leads to exacerbation of Polg-driven proteomic consequences, though it may be bioenergetically protective in tissues exhibiting rapid mitochondrial turnover. Finally, we provide evidence that, surprisingly, dis-autoinhibition of Parkin (ParkinW402A) functionally resembles Parkin knockout and fails to rescue deleterious Polg-driven effects. Our study accomplishes three main outcomes: (1) it supports recent studies suggesting that Parkin dependence is low in response to an increased mtDNA mutational load, (2) it provides evidence of a potential protective role of Parkin insufficiency, and (3) it draws into question the therapeutic attractiveness of enhancing Parkin function. [ABSTRACT FROM AUTHOR]

Twenty-five years have passed since the causative gene for familial Parkinson's disease (PD), Parkin (now PRKN), was identified in 1998; PRKN is the most common causative gene in young-onset PD. Parkin encodes a ubiquitin-protein ligase, and Parkin is involved in mitophagy, a type of macroautophagy, in concert with PTEN-induced kinase 1 (PINK1). Both gene products are also involved in mitochondrial quality control. Among the many genetic PD-causing genes discovered, discovering PRKN as a cause of juvenile-onset PD has significantly impacted other neurodegenerative disorders. This is because the involvement of proteolytic systems has been suggested as a common mechanism in neurodegenerative diseases in which inclusion body formation is observed. The discovery of the participation of PRKN in PD has brought attention to the involvement of the proteolytic system in neurodegenerative diseases. Our research group has successfully isolated and identified CHCHD2, which is involved in the mitochondrial electron transfer system, and prosaposin (PSAP), which is involved in the lysosomal system, in this Parkin mechanism. Hereditary PD is undoubtedly an essential clue to solitary PD, and at least 25 or so genes and loci have been reported so far. This number of genes indicates that PD is a very diverse group of diseases. Currently, the diagnosis of PD is based on clinical symptoms and imaging studies. Although highly accurate diagnostic criteria have been published, early diagnosis is becoming increasingly important in treatment strategies for neurodegenerative diseases. Here, we also describe biomarkers that our group is working on. [ABSTRACT FROM AUTHOR]

Aim: Voltage-gated calcium (CaV) channels play an essential role in maintaining calcium homeostasis and regulating numerous physiological processes in neurons. Therefore, dysregulation of calcium signaling is relevant in many neurological disorders, including Parkinson's disease (PD). This review aims to introduce the role of CaV channels in PD and discuss some novel aspects of channel regulation and its impact on the molecular pathophysiology of the disease. Methods: an exhaustive search of the literature in the field was carried out using the PubMed database of The National Center for Biotechnology Information. Systematic searches were performed from the initial date of publication to May 2022. Results: Although α-synuclein aggregates are the main feature of PD, L-type calcium (CaV1) channels seem to play an essential role in the pathogenesis of PD. Changes in the functional expression of CaV1.3 channels alter Calcium homeostasis and contribute to the degeneration of dopaminergic neurons. Furthermore, recent studies suggest that CaV channel trafficking towards the cell membrane depends on the activity of the ubiquitin-proteasome system (UPS). In PD, there is an increase in the expression of L-type channels associated with a decrease in the expression of Parkin, an E3 enzyme of the UPS. Therefore, a link between Parkin and CaV channels could play a fundamental role in the pathogenesis of PD and, as such, could be a potentially attractive target for therapeutic intervention. Conclusion: The study of alterations in the functional expression of CaV channels will provide a framework to understand better the neurodegenerative processes that occur in PD and a possible path toward identifying new therapeutic targets to treat this condition. [ABSTRACT FROM AUTHOR]

The ubiquitin kinase-ligase pair PINK1-PRKN recognizes and transiently labels damaged mitochondria with ubiquitin phosphorylated at Ser65 (p-S65-Ub) to mediate their selective degradation (mitophagy). Complete loss of PINK1 or PRKN function unequivocally leads to early-onset Parkinson disease, but it is debated whether impairments in mitophagy contribute to disease later in life. While the pathway has been extensively studied in cell culture upon acute and massive mitochondrial stress, basal levels of activation under endogenous conditions and especially in vivo in the brain remain undetermined. Using rodent samples, patient-derived cells, and isogenic neurons, we here identified age-dependent, brain region-, and cell type-specific effects and determined expression levels and extent of basal and maximal activation of PINK1 and PRKN. Our work highlights the importance of defining critical risk and therapeutically relevant levels of PINK1-PRKN signaling which will further improve diagnosis and prognosis and will lead to better stratification of patients for future clinical trials. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a complex and debilitating neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra. The pathogenesis of PD is intimately linked to the roles of two key molecular players, α-synuclein (α-syn) and Parkin. Understanding the intricate interplay between α-syn and Parkin is essential for unravelling the molecular underpinnings of PD. Their roles in synaptic function and protein quality control underscore their significance in neuronal health. Dysregulation of these processes, as seen in PD, highlights the potential for targeted therapeutic strategies aimed at restoring normal protein homeostasis and mitigating neurodegeneration. Investigating the connections between α-syn, Parkin, and various pathological mechanisms provides insights into the complex web of factors contributing to PD pathogenesis and offers hope for the development of more effective treatments for this devastating neurological disorder. The present compilation provides an overview of their structures, regional and cellular locations, associations, physiological functions, and pathological roles in the context of PD. [ABSTRACT FROM AUTHOR]

Parkin regulates protein degradation and mitophagy in dopaminergic neurons. Deficiencies in Parkin expression or function lead to cellular stress, cell degeneration, and the death of dopaminergic neurons, which promotes Parkinson's disease. In contrast, Parkin overexpression promotes neuronal survival. Therefore, the mechanisms of Parkin upregulation are crucial to understand. We describe here the molecular mechanism of AHR-mediated Parkin regulation in human SH-SY5Y neuroblastoma cells. Specifically, we report that the human Parkin gene (PRKN) is transcriptionally upregulated by the aryl hydrocarbon receptor (AHR) through two different selective ligand-dependent pathways. 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), a stress-inducing AHR ligand, indirectly promotes PRKN transcription by inducing ATF4 expression via TCDD-mediated endoplasmic reticulum (ER) stress. In contrast, kynurenine, a nontoxic AHR agonist, induces PRKN transcription by promoting AHR binding to the PRKN promoter without activating ER stress. Our results demonstrate that AHR activation may be a potential pharmacological pathway to induce human Parkin, but such a strategy must carefully consider the choice of AHR ligand to avoid neurotoxic side effects. [Display omitted] • AHR signaling upregulates human PRKN gene in SH-SY5Y neuroblastoma cells. • TCDD-mediated Parkin induction involves ER stress and AHR-dependent ATF4 induction. • Kynurenine-mediated Parkin induction involves the canonic-genomic AHR signaling. • Kynurenine and TCDD induce AHR-dependent Parkin expression by different pathways. [ABSTRACT FROM AUTHOR]

The relationship between mitophagy, a selective form of macroautophagy/autophagy that targets dysfunctional or excessive amounts of irregular mitochondria for degradation, and mycophagy, a selective autophagy mechanism for the removal of dysfunctional/unwanted lysosomes, in the context of intervertebral disc degeneration (IVDD) has not been sufficiently elucidated. This study was conducted to investigate the question, "Can IVDD be delayed or halted through pharmacological targeting of mitophagic or dysphagic signaling pathways?". For this purpose, systematic searches were conducted in the PubMed electronic database without country or language restrictions until March 21, 2024, using sequential searches with keywords related to the topic using "and/or" combinations to select high-evidence studies. Findings from studies meeting the research criteria and undergoing full-text assessment were compiled into an Excel spreadsheet using Microsoft Office. Results are presented in counts and/or frequencies (%). Following a comprehensive literature search, 12.720 studies were encountered, with 11.49% being reviewed. Although no clinical research related to the topic was found, no studies fully encompassed the inclusion criteria or the keywords "mitophagy"/"lysophagy" with "IVDD". Based on the existing literature, it is impossible to determine the level of evidence regarding the effect of mitophagic and/or dysphagic signaling pathways on IVDD or to discuss the effectiveness and reliability of targeting these pathways in treating degeneration. To establish evidence-based conclusions on this research topic, findings from multicenter, double-blind, randomized, and clinical trials involving a larger number of cases in different populations need to be evaluated. [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr(VI)) is a hazardous metallic compound commonly used in industrial processes. The liver, responsible for metabolism and detoxification, is the main target organ of Cr(VI). Toxicity experiments were performed to investigate the impacts of low-dose exposure to Cr(VI) on rat livers. It was revealed that exposure of 0.05 mg/kg potassium dichromate (K2Cr2O7) and 0.25 mg/kg K2Cr2O7 notably increased malondialdehyde (MDA) levels and the expressions of P-AMPK, P-ULK, PINK1, P-Parkin, and LC3II/LC3I, and significantly reduced SOD activity and P-mTOR and P62 expression levels in liver. Electron microscopy showed that CR(VI) exposure significantly increased mitophagy and the destruction of mitochondrial structure. This study simulates the respiratory exposure mode of CR(VI) workers through intratracheal instillation of CR(VI) in rats. It confirms that autophagy in hepatocytes is induced by low concentrations of CR(VI) and suggest that the liver damage caused by CR(VI) may be associated with the AMPK-related PINK/Parkin signaling pathway.

The serine/threonine kinase, PINK1, and the E3 ubiquitin ligase, PRKN/Parkin facilitate LC3-dependent autophagosomal encasement and lysosomal clearance of dysfunctional mitochondria, and defects in this pathway contribute to the pathogenesis of numerous cardiometabolic and neurological diseases. Although dynamic actin remodeling has recently been shown to play an important role in governing spatiotemporal control of mitophagy, the mechanisms remain unclear. We recently found that the RhoGAP, ARHGAP26/GRAF1 is a PRKN-binding protein that is rapidly recruited to damaged mitochondria where upon phosphorylation by PINK1 it serves to coordinate phagophore capture by regulating mitochondrial-associated actin remodeling and by facilitating PRKN-LC3 interactions. Because ARHGAP26 phosphorylation on PINK1-dependent sites is dysregulated in human heart failure and ARHGAP26 depletion in mouse hearts blunts mitochondrial clearance and attenuates compensatory metabolic adaptations to stress, this enzyme may be a tractable target to treat the many diseases associated with mitochondrial dysfunction. [ABSTRACT FROM AUTHOR]

Loss of proteostasis and dysregulated mitochondrial function are part of the traditional hallmarks of aging, and in their last revision impaired macroautophagy and chronic inflammation are also included. Mitophagy is at the intersection of all these processes but whether it undergoes age-associated perturbations was not known. In our recent work, we performed a systematic and systemic analysis of mitolysosome levels in mice and found that, despite the already-known decrease in nonselective macroautophagy, mitophagy remains stable or increases upon aging in all tissues analyzed and is mediated by the PINK1-PRKN-dependent pathway. Further analyses revealed a concomitant increase in mtDNA leakage into the cytosol and activation of the CGAS-STING1 inflammation axis. Notably, both phenomena are also observed in primary fibroblasts from aged human donors. We hypothesized that mitophagy might be selectively upregulated during aging to improve mitochondrial fitness and reduce mtDNA-induced inflammation. Treatment with the mitophagy inducer urolithin A alleviates age-associated neurological decline, including improved synaptic connectivity, cognitive memory and visual function. Supporting our initial hypothesis, urolithin A reduces the levels of cytosolic mtDNA, CGAS-STING1 activation and neuroinflammation. Finally, using an in vitro model of mitochondrial membrane permeabilization we validated that PINK1-PRKN-mediated mitophagy is essential to resolve cytosolic mtDNA-triggered inflammation. These findings open up an integrative approach to tackle aging and increase healthspan via mitophagy induction. [ABSTRACT FROM AUTHOR]

Abstract Aim The present study aimed to examine the association between copy number variations (CNVs) in parkin (PRKN) and schizophrenia (SCZ) and autism spectrum disorder (ASD) in a large case–control sample. Method Array comparative genomic hybridization was performed on 3111 cases with SCZ, 1236 cases with ASD, and 2713 controls. We systematically prioritized likely pathogenic CNVs (LP‐CNVs) in PRKN and examined their association with SCZ and ASD. Results In total, 3014 SCZ cases (96.9%), 1205 ASD cases (97.5%), and 2671 controls (98.5%) passed quality control. We found that monoallelic carriers of LP‐CNVs in PRKN were common (70/6890, 1.02%) and were not at higher risk of SCZ (p = 0.29) or ASD (p = 0.72). We observed that the distribution pattern of LP‐CNVs in the Japanese population was consistent with those in other populations. We also identified a patient diagnosed with SCZ and early‐onset Parkinson's disease carrying biallelic pathogenic CNVs in PRKN. The absence of Parkinson's symptoms in 10 other monoallelic carriers of the same pathogenic CNV further reflects the lack of effect of monoallelic pathogenic variants in PRKN in the absence of a second hit. Conclusion The present findings suggest that monoallelic CNVs in PRKN do not confer a significant risk for SCZ or ASD. However, further studies to investigate the association between biallelic CNVs in PRKN and SCZ and ASD are warranted.

ABSTRACT Aims This research aimed to investigate the specific mechanism of methyltransferase like 3 (METTL3) in the progression of diabetic kidney disease (DKD). Materials and Methods The model of diabetic kidney disease was established with HK‐2 cells and mice in vitro and in vivo. The N6 methyladenosine (m6A) contents in the cells and tissues were detected with a commercial kit and the m6A levels of PTEN induced putative kinase 1 (PINK2) were detected with a MeRIP kit. The mRNA and protein levels were determined with RT‐qPCR and western blot. The ROS, TNF‐α, and IL‐6 levels were assessed with ELISA. The cell proliferative ability was measured by a CCK‐8 assay and cell apoptosis was determined with TUNEL staining. The HE and Masson staining was performed to observe the renal morphology. The RIP assay was conducted to detect the interaction between METTL3/YTHDF2 and PINK1. Results The m6A content and METTL3 levels were prominently elevated in diabetic kidney disease. METTL3 silencing promoted the cell growth and the expression of LC3 II, PINK1, and Parkin, while inhibiting the cell apoptosis and the expression of LC3 I and p62 in the high glucose (HG) stimulated HK‐2 cells. METTL3 silencing also decreased the ROS, TNF‐α, and IL‐6 levels in diabetic kidney disease. PINK1 silencing neutralized the function of sh‐METTL3 in the HG stimulated HK‐2 cells. The HE and Masson staining showed that METTL3 silencing alleviated the kidney injury induced by DKD. METTL3 silencing decreased the m6A levels of PINK1, while increased the mRNA levels of PINK1 which depended on YTHDF2. Conclusions METTL3 silencing could inhibit the progression of diabetic nephropathy in vivo and in vitro by regulating the m6A modification of PINK1, which depends on YTHDF2. Our research lays the theoretical foundation for the precise treatment of diabetic kidney disease and the development of targeted drugs in the future.

Abstract Background Loss-of-function mutations in the PRKN gene, encoding Parkin, are the most common cause of autosomal recessive Parkinson’s disease (PD). We have previously identified mitoch ondrial Stomatin-like protein 2 (SLP-2), which functions in the assembly of respiratory chain proteins, as a Parkin-binding protein. Selective knockdown of either Parkin or SLP-2 led to reduced mitochondrial and neuronal function in neuronal cells and Drosophila, where a double knockdown led to a further worsening of Parkin-deficiency phenotypes. Here, we investigated the minimal Parkin region involved in the Parkin-SLP-2 interaction and explored the ability of Parkin-fragments and peptides from this minimal region to restore mitochondrial function. Methods In fibroblasts, human induced pluripotent stem cell (hiPSC)-derived neurons, and neuroblastoma cells the interaction between Parkin and SLP-2 was investigated, and the Parkin domain responsible for the binding to SLP-2 was mapped. High resolution respirometry, immunofluorescence analysis and live imaging were used to analyze mitochondrial function. Results Using a proximity ligation assay, we quantitatively assessed the Parkin-SLP-2 interaction in skin fibroblasts and hiPSC-derived neurons. When PD-associated PRKN mutations were present, we detected a significantly reduced interaction between the two proteins. We found a preferential binding of SLP-2 to the N-terminal part of Parkin, with a highest affinity for the RING0 domain. Computational modeling based on the crystal structure of Parkin protein predicted several potential binding sites for SLP-2 within the Parkin RING0 domain. Amongst these, three binding sites were observed to overlap with natural PD-causing missense mutations, which we demonstrated interfere substantially with the binding of Parkin to SLP-2. Finally, delivery of the isolated Parkin RING0 domain and a Parkin mini-peptide, conjugated to cell-permeant and mitochondrial transporters, rescued compromised mitochondrial function in Parkin-deficient neuroblastoma cells and hiPSC-derived neurons with endogenous, disease causing PRKN mutations. Conclusions These findings place further emphasis on the importance of the protein–protein interaction between Parkin and SLP-2 for the maintenance of optimal mitochondrial function. The possibility of restoring an abolished binding to SLP-2 by delivering the Parkin RING0 domain or the Parkin mini-peptide involved in this specific protein–protein interaction into cells might represent a novel organelle-specific therapeutic approach for correcting mitochondrial dysfunction in Parkin-linked PD.

Complete loss-of-function mutations in the PRKN gene are a major cause of early-onset Parkinson's disease (PD). PRKN encodes the Parkin protein, an E3 ubiquitin ligase that works in conjunction with the ubiquitin kinase PINK1 in a distinct quality control pathway to tag damaged mitochondria for autophagic clearance, i.e., mitophagy. According to previous structural investigations, Parkin protein is typically kept in an inactive conformation via several intramolecular, auto-inhibitory interactions. Here, we performed molecular dynamics simulations (MDS) to provide insights into conformational changes occurring during the de-repression of Parkin and the gain of catalytic activity. We analyzed four different Parkin-activating mutations that are predicted to disrupt certain aspects of its auto-inhibition. All four variants showed greater conformational motions compared to wild-type protein, as well as differences in distances between domain interfaces and solvent-accessible surface area, which are thought to play critical roles as Parkin gains catalytic activity. Our findings reveal that the studied variants exert a notable influence on Parkin activation as they alter the opening of its closed inactive structure, a finding that is supported by recent structure- and cell-based studies. These findings not only helped further characterize the hyperactive variants but overall improved our understanding of Parkin's catalytic activity and nominated targets within Parkin's structure for potential therapeutic designs. [ABSTRACT FROM AUTHOR]

The PTEN-induced kinase 1 (PINK1)-Parkin pathway plays a vital role in maintaining a healthy pool of mitochondria in higher eukaryotic cells. While the downstream components of this pathway are well understood, the upstream triggers remain less explored. In this study, we conducted an extensive analysis of inhibitors targeting various mitochondrial electron transport chain (ETC) complexes to investigate their potential as activators of the PINK1–Parkin pathway. We identified cloflucarban, an antibacterial compound, as a novel pathway activator that simultaneously inhibits mitochondrial complexes III and V, and V. RNA interference (RNAi) confirmed that the dual inhibition of these complexes activates the PINK1–Parkin pathway. Intriguingly, we discovered that albumin, specifically bovine serum albumin (BSA) and human serum albumin (HSA) commonly present in culture media, can hinder carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-induced pathway activation. However, cloflucarban's efficacy remains unaffected by albumin, highlighting its reliability for studying the PINK1–Parkin pathway. This study provides insights into the activation of the upstream PINK1–Parkin pathway and underscores the influence of culture conditions on research outcomes. Cloflucarban emerges as a promising tool for investigating mitochondrial quality control and neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Background: Bisphenol A (BPA), an endocrine-disrupting agent, is widely used as polycarbonate plastics for producing food containers. BPA exposure at environmentally relevant concentrations can cause reproductive disorders. Objective: The effect of Naringenin (NG) on BPA-induced Sertoli cell toxicity and its mechanism was examined in the present study. Materials and Methods: In this experimental-laboratory study, the mouse TM4 cells were treated to BPA (0.8 µM) or NG for 24 hr at concentrations of 10, 20, and 50 µg/ml. Cell viability, reactive oxygen species (ROS) production, malondialdehyde (MDA) content, antioxidant level, and mitochondrial membrane potential (MMP) were examined. The expression of mitophagy-related genes, including Parkin and PTEN-induced putative kinase 1 (Pink1), was also evaluated. Results: BPA significantly lowered the viability of the Sertoli cells (p = 0.004). Pink1 and Parkin levels of the BPA group were significantly increased (p < 0.001), while the MMP was considerably decreased (p < 0.001). BPA raised MDA and ROS levels (p < 0.001) and reduced antioxidant biomarkers (p = 0.003). NG at the 20 and 50 µg/ml concentrations could significantly improve the viability and MMP of TM4 cells (p = 0.034). NG depending on concentration, could decrease Pink1 and Parkin at mRNA and protein levels compared to the BPA group (p = 0.024). NG enhanced antioxidant factors, while ROS and MDA levels were decreased in the BPA-exposed cells. Conclusion: The beneficial impacts of NG on BPA-exposed Sertoli cells are related to the suppression of mitophagy and the reduction of oxidative stress. [ABSTRACT FROM AUTHOR]

Aim: The present study aimed to examine the association between copy number variations (CNVs) in parkin (PRKN) and schizophrenia (SCZ) and autism spectrum disorder (ASD) in a large case–control sample. Method: Array comparative genomic hybridization was performed on 3111 cases with SCZ, 1236 cases with ASD, and 2713 controls. We systematically prioritized likely pathogenic CNVs (LP‐CNVs) in PRKN and examined their association with SCZ and ASD. Results: In total, 3014 SCZ cases (96.9%), 1205 ASD cases (97.5%), and 2671 controls (98.5%) passed quality control. We found that monoallelic carriers of LP‐CNVs in PRKN were common (70/6890, 1.02%) and were not at higher risk of SCZ (p = 0.29) or ASD (p = 0.72). We observed that the distribution pattern of LP‐CNVs in the Japanese population was consistent with those in other populations. We also identified a patient diagnosed with SCZ and early‐onset Parkinson's disease carrying biallelic pathogenic CNVs in PRKN. The absence of Parkinson's symptoms in 10 other monoallelic carriers of the same pathogenic CNV further reflects the lack of effect of monoallelic pathogenic variants in PRKN in the absence of a second hit. Conclusion: The present findings suggest that monoallelic CNVs in PRKN do not confer a significant risk for SCZ or ASD. However, further studies to investigate the association between biallelic CNVs in PRKN and SCZ and ASD are warranted. [ABSTRACT FROM AUTHOR]

Tank-binding kinase 1 (TBK1) is a Ser/Thr kinase that is involved in many intracellular processes, such as innate immunity, cell cycle, and apoptosis. TBK1 is also important for phosphorylating the autophagy adaptors that mediate the selective autophagic removal of damaged mitochondria. However, the mechanism by which PINK1-Parkin-mediated mitophagy activates TBK1 remains largely unknown. Here, we show that the autophagy adaptor optineurin (OPTN) provides a unique platform for TBK1 activation. Both the OPTN-ubiquitin and the OPTN-pre-autophagosomal structure (PAS) interaction axes facilitate assembly of the OPTN-TBK1 complex at a contact sites between damaged mitochondria and the autophagosome formation sites. At this assembly point, a positive feedback loop for TBK1 activation is initiated that accelerates hetero-autophosphorylation of the protein. Expression of monobodies engineered here to bind OPTN impaired OPTN accumulation at contact sites, as well as the subsequent activation of TBK1, thereby inhibiting mitochondrial degradation. Taken together, these data show that a positive and reciprocal relationship between OPTN and TBK1 initiates autophagosome biogenesis on damaged mitochondria. Synopsis: Tank-binding kinase 1 (TBK1), a Ser/Thr kinase involved in many intracellular processes, is important for the selective autophagic removal of damaged mitochondria. This work addresses the mechanism by which TBK1 becomes activated in this context. The autophagy adaptor optineurin (OPTN) provides a platform for TBK1 activation via autophosphorylation as damaged mitochondria are removed. OPTN accumulates at contact sites between a damaged mitochondrion and the pre-autophagosomal structure (PAS). Not only the interaction between OPTN and ubiquitin but also the interaction between OPTN and the PAS facilitates TBK1 activation. OPTN-TBK1 assembly at the contact site drives a positive feedback loop for TBK1 activation. Monobodies against OPTN physically block OPTN assembly at the contact site and impair the elimination of damaged mitochondria. Tank-binding kinase 1 localizes to clusters of optineurin on the surface of damaged mitochondria, where its autophosphorylation promotes growth of the pre-autophagosomal structure. [ABSTRACT FROM AUTHOR]

PTEN-induced putative kinase 1 (PINK1), a mitochondrial kinase that phosphorylates Parkin and other proteins, plays a crucial role in mitophagy and protection against neurodegeneration. Mutations in PINK1 and Parkin can lead to loss of function and early onset Parkinson’s disease. However, there is a lack of strong in vivo evidence in rodent models to support the theory that loss of PINK1 affects mitophagy and induces neurodegeneration. Additionally, PINK1 knockout pigs (Sus scrofa) do not appear to exhibit neurodegeneration. In our recent work involving non-human primates, we found that PINK1 is selectively expressed in primate brains, while absent in rodent brains. To extend this to other species, we used multiple antibodies to examine the expression of PINK1 in pig tissues. In contrast to tissues from cynomolgus monkeys (Macaca fascicularis), our data did not convincingly demonstrate detectable PINK1 expression in pig tissues. Knockdown of PINK1 in cultured pig cells did not result in altered Parkin and BAD phosphorylation, as observed in cultured monkey cells. A comparison of monkey and pig striatum revealed more PINK1-phosphorylated substrates in the monkey brain. Consistently, PINK1 knockout in pigs did not lead to obvious changes in the phosphorylation of Parkin and BAD. These findings provide new evidence that PINK1 expression is specific to primates, underscoring the importance of non-human primates in investigating PINK1 function and pathology related to PINK1 deficiency. [ABSTRACT FROM AUTHOR]

In recent years, research into Parkinson's disease and similar neurodegenerative disorders has increasingly suggested that these conditions are synonymous with failures in proteostasis. However, the spotlight of this research has remained firmly focused on the tail end of proteostasis, primarily aggregation, misfolding, and degradation, with protein translation being comparatively overlooked. Now, there is an increasing body of evidence supporting a potential role for translation in the pathogenesis of PD, and its dysregulation is already established in other similar neurodegenerative conditions. In this paper, we consider how altered protein translation fits into the broader picture of PD pathogenesis, working hand in hand to compound the stress placed on neurons, until this becomes irrecoverable. We will also consider molecular players of interest, recent evidence that suggests that aggregates may directly influence translation in PD progression, and the implications for the role of protein translation in our development of clinically useful diagnostics and therapeutics. [ABSTRACT FROM AUTHOR]

Introduction: As the most common cause of autosomal recessive early onset Parkinson's disease (EOPD), parkin type Parkinson's disease (PRKN-PD) may affect female patients in childbearing age. Accordingly, issues related to fertility must be adequately addressed. Here, we landscaped fertile life factors and pregnancy course of a PRKN-PD cohort, including both novel cases directly observed at our center and published ones. Methods: Six patients with confirmed PRKN-PD were examined by a structured interview on reproductive factors and associated modifications of PD disturbances, including one case followed up throughout pregnancy which was described in greater detail. Six studies reporting fertile life factors of nine PRKN-PD patients were reviewed collecting homogeneous data on fertile life and pregnancy course. Results: PRKN-PD female patients experienced motor fluctuations with the menstrual cycle, pregnancy, and puerperium, which suggests a role for sex hormones in PD clinical burden. In some cases, abortion and miscarriages occurred during the organogenesis phase in patients receiving oral antiparkinsonian therapy; however, levodopa/benserazide monotherapy resulted to be the safest choice in pregnancy. Conclusion: Collectively these data disclose the importance of pre-conception counseling in childbearing age PRKN-PD patients and EOPD in general. [ABSTRACT FROM AUTHOR]

Parkin is an ubiquitin‐E3 ligase that is involved in cellular mitophagy and was recently shown to contribute to controlling adipose tissue thermogenic plasticity. We found that Parkin expression is induced in brown (BAT) and white (WAT) adipose tissues of aged mice. We determined the potential role of Parkin in the aging-associated decline in the thermogenic capacity of adipose tissues by analyzing subcutaneous WAT, interscapular BAT, and systemic metabolic and physiological parameters in young (5 month-old) and aged (16 month-old) mice with targeted invalidation of the Parkin (Park2) gene, and their wild-type littermates. Our data indicate that suppression of Parkin prevented adipose accretion, increased energy expenditure and improved the systemic metabolic derangements, such as insulin resistance, seen in aged mice. This was associated with maintenance of browning and reduction of the age-associated induction of inflammation in subcutaneous WAT. BAT in aged mice was much less affected by Parkin gene invalidation. Such protection was associated with a dramatic prevention of the age-associated induction of fibroblast growth factor-21 (FGF21) levels in aged Parkin-invalidated mice. This was associated with a parallel reduction in FGF21 gene expression in adipose tissues and liver in aged Parkin-invalidated mice. Additionally, Parkin invalidation prevented the protein down-regulation of β-Klotho (a key co-receptor mediating FGF21 responsiveness in tissues) in aged adipose tissues. We conclude that Parkin down-regulation leads to improved systemic metabolism in aged mice, in association with maintenance of adipose tissue browning and FGF21 system functionality. [ABSTRACT FROM AUTHOR]

Background: Mitochondrial dysfunction and toxic protein aggregates have been shown to be key features in the pathogenesis of neurodegenerative diseases, such as Parkinson's disease (PD). Functional analysis of genes linked to PD have revealed that the E3 ligase Parkin and the mitochondrial kinase PINK1 are important factors for mitochondrial quality control. PINK1 phosphorylates and activates Parkin, which in turn ubiquitinates mitochondrial proteins priming them and the mitochondrion itself for degradation. However, it is unclear whether dysregulated mitochondrial degradation or the toxic build-up of certain Parkin ubiquitin substrates is the driving pathophysiological mechanism leading to PD. The iron-sulphur cluster containing proteins CISD1 and CISD2 have been identified as major targets of Parkin in various proteomic studies. Methods: We employed in vivo Drosophila and human cell culture models to study the role of CISD proteins in cell and tissue viability as well as aged-related neurodegeneration, specifically analysing aspects of mitophagy and autophagy using orthogonal assays. Results: We show that the Drosophila homolog Cisd accumulates in Pink1 and parkin mutant flies, as well as during ageing. We observed that build-up of Cisd is particularly toxic in neurons, resulting in mitochondrial defects and Ser65-phospho-Ubiquitin accumulation. Age-related increase of Cisd blocks mitophagy and impairs autophagy flux. Importantly, reduction of Cisd levels upregulates mitophagy in vitro and in vivo, and ameliorates pathological phenotypes in locomotion, lifespan and neurodegeneration in Pink1/parkin mutant flies. In addition, we show that pharmacological inhibition of CISD1/2 by rosiglitazone and NL-1 induces mitophagy in human cells and ameliorates the defective phenotypes of Pink1/parkin mutants. Conclusion: Altogether, our studies indicate that Cisd accumulation during ageing and in Pink1/parkin mutants is a key driver of pathology by blocking mitophagy, and genetically and pharmacologically inhibiting CISD proteins may offer a potential target for therapeutic intervention. [ABSTRACT FROM AUTHOR]

Background: Loss-of-function mutations in the PRKN gene, encoding Parkin, are the most common cause of autosomal recessive Parkinson's disease (PD). We have previously identified mitoch ondrial Stomatin-like protein 2 (SLP-2), which functions in the assembly of respiratory chain proteins, as a Parkin-binding protein. Selective knockdown of either Parkin or SLP-2 led to reduced mitochondrial and neuronal function in neuronal cells and Drosophila, where a double knockdown led to a further worsening of Parkin-deficiency phenotypes. Here, we investigated the minimal Parkin region involved in the Parkin-SLP-2 interaction and explored the ability of Parkin-fragments and peptides from this minimal region to restore mitochondrial function. Methods: In fibroblasts, human induced pluripotent stem cell (hiPSC)-derived neurons, and neuroblastoma cells the interaction between Parkin and SLP-2 was investigated, and the Parkin domain responsible for the binding to SLP-2 was mapped. High resolution respirometry, immunofluorescence analysis and live imaging were used to analyze mitochondrial function. Results: Using a proximity ligation assay, we quantitatively assessed the Parkin-SLP-2 interaction in skin fibroblasts and hiPSC-derived neurons. When PD-associated PRKN mutations were present, we detected a significantly reduced interaction between the two proteins. We found a preferential binding of SLP-2 to the N-terminal part of Parkin, with a highest affinity for the RING0 domain. Computational modeling based on the crystal structure of Parkin protein predicted several potential binding sites for SLP-2 within the Parkin RING0 domain. Amongst these, three binding sites were observed to overlap with natural PD-causing missense mutations, which we demonstrated interfere substantially with the binding of Parkin to SLP-2. Finally, delivery of the isolated Parkin RING0 domain and a Parkin mini-peptide, conjugated to cell-permeant and mitochondrial transporters, rescued compromised mitochondrial function in Parkin-deficient neuroblastoma cells and hiPSC-derived neurons with endogenous, disease causing PRKN mutations. Conclusions: These findings place further emphasis on the importance of the protein–protein interaction between Parkin and SLP-2 for the maintenance of optimal mitochondrial function. The possibility of restoring an abolished binding to SLP-2 by delivering the Parkin RING0 domain or the Parkin mini-peptide involved in this specific protein–protein interaction into cells might represent a novel organelle-specific therapeutic approach for correcting mitochondrial dysfunction in Parkin-linked PD. [ABSTRACT FROM AUTHOR]

One of the hallmarks of Parkinson’s Disease (PD) is aggregation of incorrectly folded α-synuclein (SNCA) protein resulting in selective death of dopaminergic neurons. Another form of PD is characterized by the loss-of-function of an E3-ubiquitin ligase, parkin. Mutations in SNCA and parkin result in impaired mitochondrial morphology, causing loss of dopaminergic neurons. Despite extensive research on the individual effects of SNCA and parkin, their interactions in dopaminergic neurons remain understudied. Here we employ Drosophila model to study the effect of collective overexpression of SNCA along with the downregulation of parkin in the dopaminergic neurons of the posterior brain. We found that overexpression of SNCA along with downregulation of parkin causes a reduction in the number of dopaminergic neuronal clusters in the posterior region of the adult brain, which is manifested as progressive locomotor dysfunction. Overexpression of SNCA and downregulation of parkin collectively results in altered mitochondrial morphology in a cluster-specific manner, only in a subset of dopaminergic neurons of the brain. Further, we found that SNCA overexpression causes transcriptional downregulation of parkin. However, this downregulation is not further enhanced upon collective SNCA overexpression and parkin downregulation. This suggests that the interactions of SNCA and parkin may not be additive. Our study thus provides insights into a potential link between α-synuclein and parkin interactions. These interactions result in altered mitochondrial morphology in a cluster-specific manner for dopaminergic neurons over a time, thus unraveling the molecular interactions involved in the etiology of Parkinson’s Disease. [ABSTRACT FROM AUTHOR]

Arrestins were discovered for their role in homologous desensitization of G‐protein‐coupled receptors (GPCRs). Later non‐visual arrestins were shown to regulate several signaling pathways. Some of these pathways require arrestin binding to GPCRs, the regulation of others is receptor independent. Here, we demonstrate that arrestin‐3 binds the E3 ubiquitin ligase parkin via multiple sites, preferentially interacting with its RING0 domain. Identification of the parkin domains involved suggests that arrestin‐3 likely relieves parkin autoinhibition and/or stabilizes the enzymatically active “open” conformation of parkin. Arrestin‐3 binding enhances ubiquitination by parkin of the mitochondrial protein mitofusin‐1 and facilitates parkin‐mediated mitophagy in HeLa cells. Furthermore, arrestin‐3 and its mutant with enhanced parkin binding rescue mitofusin‐1 ubiquitination and mitophagy in the presence of the Parkinson's disease‐associated R275W parkin mutant, which is defective in both functions. Thus, modulation of parkin activity via arrestin‐3 might be a novel strategy of anti‐parkinsonian therapy. [ABSTRACT FROM AUTHOR]

Parknson's disease (PD) is the second most common neurodegenerative disease, affecting 1% of people aged over 60. PD is characterized by a wide range of motor symptoms, however the clinical spectrum of PD covers a wide range of non-motor symptoms, as well. Sleep disorders are among the most common non-motor symptoms of PD, can occur at any stage of the disease and significantly affect quality of life. These include rapid eye movement sleep behavior disorder (RBD), restless legs syndrome (RLS), excessive daytime sleepiness (EDS), insomnia, obstructive sleep apnea (OSA) and circadian rhythm disturbances. One of the main challenges in PD research is identifying individuals during the prodromal phase of the disease. Combining genetic and prodromal data may aid the early identification of individuals susceptible to PD. This review highlights current data regarding the genetic component of sleep disorders in PD patients, focusing on genes that have currently been associated with this PD co-morbidity. [ABSTRACT FROM AUTHOR]

This article discusses a case study of a 21-year-old woman with juvenile-onset Parkinson's disease (PD) who was treated with deep brain stimulation (DBS). The study aimed to understand the fluctuation of motor symptoms during different phases of the menstrual cycle. The patient experienced more "off" periods with painful dystonia during the luteal phase of her menstrual cycle. The study found associations between the levels of progesterone and the modulation of beta band activity in the subthalamic nucleus (STN), highlighting the role of sex hormones in the response to medication. The study provides insights into the complex relationship between sex hormones and motor fluctuations in PD. [Extracted from the article]

Oxaliplatin-induced peripheral nerve pain (OIPNP) is a common chemotherapy-related complication, but the mechanism is complex. Mitochondria are vital for cellular homeostasis and regulating oxidative stress. Parkin-mediated mitophagy is a cellular process that removes damaged mitochondria, exhibiting a protective effect in various diseases; however, its role in OIPNP remains unclear. In this study, we found that Parkin-mediated mitophagy was decreased, and reactive oxygen species (ROS) was upregulated in OIPNP rat dorsal root ganglion (DRG) in vivo and in PC12 cells stimulated with oxaliplatin (OXA) in vitro. Overexpression of Parkin indicated that OXA might cause mitochondrial and cell damage by inhibiting mitophagy. We also showed that salidroside (SAL) upregulated Parkin-mediated mitophagy to eliminate damaged mitochondria and promote PC12 cell survival. Knockdown of Parkin indicated that mitophagy is crucial for apoptosis and mitochondrial homeostasis in PC12 cells. In vivo study also demonstrated that SAL enhances Parkin-mediated mitophagy in the DRG and alleviates peripheral nerve injury and pain. These results suggest that Parkin-mediated mitophagy is involved in the pathogenesis of OIPNP and may be a potential therapeutic target for OIPNP. NEW & NOTEWORTHY: This article discusses the effects and mechanisms of Parkin-mediated mitophagy in oxaliplatin-induced peripheral nerve pain (OIPNP) from both in vivo and in vitro. We believe that our study makes a significant contribution to the literature because OIPNP has always been the focus of clinical medicine, and mitochondrial quality regulation mechanisms especially Parkin-mediated mitophagy, have been deeply studied in recent years. We use a variety of molecular biological techniques and animal experiments to support our argument. [ABSTRACT FROM AUTHOR]

Mitochondria are crucial for cellular ATP production. They are highly dynamic organelles, whose morphology and function are controlled through mitochondrial fusion and fission. The specific roles of mitochondria in podocytes, the highly specialized cells of the kidney glomerulus, remain less understood. Given the significant structural, functional, and molecular similarities between mammalian podocytes and Drosophila nephrocytes, we employed fly nephrocytes to explore the roles of mitochondria in cellular function. Our study revealed that alterations in the Pink1–Park (mammalian PINK1–PRKN) pathway can disrupt mitochondrial dynamics in Drosophila nephrocytes. This disruption led to either fragmented or enlarged mitochondria, both of which impaired mitochondrial function. The mitochondrial dysfunction subsequently triggered defective intracellular endocytosis, protein aggregation, and cellular damage. These findings underscore the critical roles of mitochondria in nephrocyte functionality.

BackgroundSarcopenia is characterized by the loss of skeletal muscle mass and strength and is associated with poor prognosis in patients with chronic obstructive pulmonary disease (COPD). Cigarette smoke (CS) exposure, a major cause for COPD, induces mitochondrial damage, which has been implicated in sarcopenia pathogenesis. The current study sought to examine the involvement of insufficient Parkin-mediated mitophagy, a mitochondrion-selective autophagy, in the mechanisms by which dysfunctional mitochondria accumulate with excessive reactive oxygen species (ROS) production in the development of COPD-related sarcopenia.MethodsThe involvement of Parkin-mediated mitophagy was examined using in vitro models of myotube formation, in vivo CS-exposure model using Parkin-/- mice, and human muscle samples from patients with COPD-related sarcopenia.ResultsCigarette smoke extract (CSE) induced myotube atrophy with concomitant 30% reduction in Parkin expression levels (P

Mitochondrial dysregulation, such as mitochondrial complex I deficiency, increased oxidative stress, perturbation of mitochondrial dynamics and mitophagy, has long been implicated in the pathogenesis of PD. Initiating from the observation that mitochondrial toxins cause PD-like symptoms and mitochondrial DNA mutations are associated with increased risk of PD, many mutated genes linked to familial forms of PD, including PRKN, PINK1, DJ-1 and SNCA, have also been found to affect the mitochondrial features. Recent research has uncovered a much more complex involvement of mitochondria in PD. Disruption of mitochondrial quality control coupled with abnormal secretion of mitochondrial contents to dispose damaged organelles may play a role in the pathogenesis of PD. Furthermore, due to its bacterial ancestry, circulating mitochondrial DNAs can function as damage-associated molecular patterns eliciting inflammatory response. In this review, we summarize and discuss the connection between mitochondrial dysfunction and PD, highlighting the molecular triggers of the disease process, the intra- and extracellular roles of mitochondria in PD as well as the therapeutic potential of mitochondrial transplantation. [ABSTRACT FROM AUTHOR]

Parkin, the gene responsible for hereditary Parkinson's disease (PD) called "Autosomal Recessive Juvenile Parkinsonism (AR-JP)" was discovered a quarter of a century ago. Owing to its huge gene structure and unique protein functions, parkin has become a subject of interest to those involved in PD research and researchers and clinicians in various fields and is being vigorously studied worldwide in relation to its nature and disease. The gene structure was registered under the gene name "parkin" in the GenBank in 1997. In 1998, deletion and point mutations in the parkin gene were reported, thereby demonstrating parkin is the causative gene for hereditary PD. Although 25 years have passed since the gene's discovery and many researchers have worked tirelessly to elucidate the function of the Parkin protein and the mechanism of its role against neuronal cell death and pathogenesis remain unknown, which raises a major question concerning the current leading hypothesis. In this review, we present the results of related research on the parkin gene in chronological order and discuss unresolved problems concerning its function and pathology as well as new trends in the research conducted to solve them. The relationship between parkin and tumorigenesis has also been addressed from the perspective of Parkin's redox molecule. [ABSTRACT FROM AUTHOR]