Parkin deficiency exacerbate ethanol-induced dopaminergic neurodegeneration by P38 pathway dependent inhibition of autophagy and mitochondrial function

Vitexin enhances mitophagy and improves renal ischemia-reperfusion injury by regulating the p38/MAPK pathway

Vitexin (VI) is a naturally occurring flavonoid derived from the leaves and seeds of Vitex, recognized for its strong antioxidant properties. This study aims to explore its effects on renal ischemia-reperfusion injury (IRI) and investigate the underlying mechanisms. We utilized hypoxia-reoxygenation (H/R) models with HK-2 cell lines and renal ischemia-reperfusion (I/R) models in mice, applying vitexin preconditioning to assess its influence on renal IRI. Our findings reveal that vitexin mitigated oxidative stress, decreased cell apoptosis, and reduced the expression of renal damage indicators such as kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL), along with an overall improvement in renal function. To further investigate the mechanism, we used network pharmacology and molecular docking techniques to predict potential vitexin targets in renal IRI. Results from Western blotting and immunofluorescence assays indicate that vitexin may promote mitophagy by suppressing the phosphorylation of the pivotal p38 protein in the p38/MAPK signaling pathway, offering protection against renal IRI. The findings indicate that vitexin could potentially be used as a therapeutic agent to alleviate renal IRI.

Parkin inhibits iron overload-induced cardiomyocyte ferroptosis by ubiquitinating ACSL4 and modulating PUFA-phospholipids metabolism

Iron overload is strongly associated with heart disease. Ferroptosis is a new form of regulated cell death indicated in cardiac ischemia-reperfusion (I/R) injury. However, the specific molecular mechanism of myocardial injury caused by iron overload in the heart is still unclear, and the involvement of ferroptosis in iron overload-induced myocardial injury is not fully understood. In this study, we observed that ferroptosis participated in developing of iron overload and I/R-induced cardiomyopathy. Mechanistically, we discovered that Parkin inhibited iron overload-induced ferroptosis in cardiomyocytes by promoting the ubiquitination of long-chain acyl-CoA synthetase 4 (ACSL4), a crucial protein involved in ferroptosis-related lipid metabolism pathways. Additionally, we identified p53 as a transcription factor that transcriptionally suppressed Parkin expression in iron-overloaded cardiomyocytes, thereby regulating iron overload-induced ferroptosis. In animal studies, cardiac-specific Parkin knockout mice (Myh6-CreER T2 /Parkin fl/fl ) fed a high-iron diet presented more severe myocardial damage, and the high iron levels exacerbated myocardial I/R injury. However, the ferroptosis inhibitor Fer-1 significantly suppressed iron overload-induced ferroptosis and myocardial I/R injury. Moreover, Parkin effectively protected against impaired mitochondrial function and prevented iron overload-induced mitochondrial lipid peroxidation. These findings unveil a novel regulatory pathway involving p53-Parkin-ACSL4 in heart disease by inhibiting of ferroptosis.

Roles of Oxidative Stress and Autophagy in Alcohol-Mediated Brain Damage

Excessive alcohol consumption significantly impacts human health, particularly the brain, due to its susceptibility to oxidative stress, which contributes to neurodegenerative conditions. Alcohol metabolism in the brain occurs primarily via catalase, followed by CYP2E1 pathways. Excess alcohol metabolized by CYP2E1 generates reactive oxygen/nitrogen species (ROS/RNS), leading to cell injury via altering many different pathways. Elevated oxidative stress impairs autophagic processes, increasing post-translational modifications and further exacerbating mitochondrial dysfunction and ER stress, leading to cell death. The literature highlights that alcohol-induced oxidative stress disrupts autophagy and mitophagy, contributing to neuronal damage. Key mechanisms include mitochondrial dysfunction, ER stress, epigenetics, and the accumulation of oxidatively modified proteins, which lead to neuroinflammation and impaired cellular quality control. These processes are exacerbated by chronic alcohol exposure, resulting in the suppression of protective pathways like NRF2-mediated antioxidant responses and increased susceptibility to neurodegenerative changes in the brain. Alcohol-mediated neurotoxicity involves complex interactions between alcohol metabolism, oxidative stress, and autophagy regulation, which are influenced by various factors such as drinking patterns, nutritional status, and genetic/environmental factors, highlighting the need for further molecular studies to unravel these mechanisms and develop targeted interventions.

Uncovering potential molecular markers and pathological mechanisms of Parkinson's disease and myocardial infarction based on bioinformatics analysis

BACKGROUND

The direct association between Parkinson's disease (PD) and Myocardial infarction (MI) has been the subject of relatively limited research.

OBJECTIVE

The purpose of this study was to identify the genes most associated with PD and MI to explore their common pathogenesis.

METHODS

The gene expression profiles of PD and MI were downloaded from GEO database. Differential expression analysis was performed to identify the common differential expression genes (DEGs) of PD and MI, followed by functional annotation. Subsequently, protein-protein interaction network were constructed, and hub DEGs were identified based on CytoHubba plugin and LASSO regression analysis. To explore the potential molecular mechanism of hub DEGs, GSEA analysis, immune correlation analysis, drug prediction and molecular docking were performed, and transcription factors (TF) and lncRNA-miRNA-mRNA (ceRNA) regulatory networks were constructed.

RESULTS

A total of 48 DEGs with the same expression trend were identified in the MI vs. normal control (NC) and PD vs. NC groups. Functional annotation results showed that the common DEGs were significantly enriched in immune and inflammation-related pathways. RPS4Y1 and UTY were the most relevant hub DEGs for PD and MI, and may be involved in the HALLMARK_MYC_TARGETS_V1 and HALLMARK_PROTEIN_SECRETION pathways. TP63 was a common TF of RPS4Y1 and UTY. The PVT1/KCNQ1OT1-hsa-miR-31-5p-RPS4Y1 and KCNQ1OT1-hsa-let-7a-5p/hsa-miR-19b-3p-UTY axes may play an important role in regulating PD and MI. CYCLOHEXIMIDE and ATALAREN may be potential drugs for the treatment of PD and MI comorbidity. In addition, PD and MI exhibit different patterns of immune cell infiltration and immune function status, which may be related to the specific pathological processes of the disease.

CONCLUSIONS

This study revealed for the first time that RPS4Y1 and UTY may be common biomarkers of PD and MI and may be potential therapeutic targets. This study provides new perspective on the common molecular mechanisms between PD and MI.

The NRF2 activator RTA-408 ameliorates chronic alcohol exposure-induced cognitive impairment and NLRP3 inflammasome activation by modulating impaired mitophagy initiation

BACKGROUND

Chronic alcohol exposure induces cognitive impairment and NLRP3 inflammasome activation in the mPFC (medial prefrontal cortex). Mitophagy plays a crucial role in neuroinflammation, and dysregulated mitophagy is associated with behavioral deficits. However, the potential relationships among mitophagy, inflammation, and cognitive impairment in the context of alcohol exposure have not yet been studied. NRF2 promotes the process of mitophagy, while alcohol inhibits NRF2 expression. Whether NRF2 activation can ameliorate defective mitophagy and neuroinflammation in the presence of alcohol remains unknown.

METHODS

BV2 cells and primary microglia were treated with alcohol. C57BL/6J mice were repeatedly administered alcohol intragastrically. BNIP3-siRNA, PINK1-siRNA, CCCP and bafilomycin A1 were used to regulate mitophagy in BV2 cells. RTA-408 acted as an NRF2 activator. Mitochondrial dysfunction, mitophagy and NLRP3 inflammasome activation were assayed. Behavioral tests were used to assess cognition.

RESULTS

Chronic alcohol exposure impaired the initiation of both receptor-mediated mitophagy and PINK1-mediated mitophagy in the mPFC and in vitro microglial cells. Silencing BNIP3 or PINK1 induced mitochondrial dysfunction and aggravated alcohol-induced NLRP3 inflammasome activation in BV2 cells. In addition, alcohol exposure inhibited the NRF2 expression both in vivo and in vitro. NRF2 activation by RTA-408 ameliorated NLRP3 inflammasome activation and mitophagy downregulation in microglia, ultimately improving cognitive impairment in the presence of alcohol.

CONCLUSION

Chronic alcohol exposure-induced impaired mitophagy initiation contributed to NLRP3 inflammasome activation and cognitive deficits, which could be alleviated by NRF2 activation via RTA-408.

Alcohol Exposure Induces Nucleolar Stress and Apoptosis in Mouse Neural Stem Cells and Late-Term Fetal Brain

Prenatal alcohol exposure (PAE) is a leading cause of neurodevelopmental disability through its induction of neuronal growth dysfunction through incompletely understood mechanisms. Ribosome biogenesis regulates cell cycle progression through p53 and the nucleolar cell stress response. Whether those processes are targeted by alcohol is unknown. Pregnant C57BL/6J mice received 3 g alcohol/kg daily at E8.5-E17.5. Transcriptome sequencing was performed on the E17.5 fetal cortex. Additionally, primary neural stem cells (NSCs) were isolated from the E14.5 cerebral cortex and exposed to alcohol to evaluate nucleolar stress and p53/MDM2 signaling. Alcohol suppressed KEGG pathways involving ribosome biogenesis (rRNA synthesis/processing and ribosomal proteins) and genes that are mechanistic in ribosomopathies (Polr1d, Rpl11; Rpl35; Nhp2); this was accompanied by nucleolar dissolution and p53 stabilization. In primary NSCs, alcohol reduced rRNA synthesis, caused nucleolar loss, suppressed proliferation, stabilized nuclear p53, and caused apoptosis that was prevented by dominant-negative p53 and MDM2 overexpression. Alcohol's actions were dose-dependent and rapid, and rRNA synthesis was suppressed between 30 and 60 min following alcohol exposure. The alcohol-mediated deficits in ribosomal protein expression were correlated with fetal brain weight reductions. This is the first report describing that pharmacologically relevant alcohol levels suppress ribosome biogenesis, induce nucleolar stress in neuronal populations, and involve the ribosomal/MDM2/p53 pathway to cause growth arrest and apoptosis. This represents a novel mechanism of alcohol-mediated neuronal damage.

Microarray-based Analysis of Differential Gene Expression Profile in Rotenone-induced Parkinson's Disease Zebrafish Model

BACKGROUND & OBJECTIVES

Despite much clinical and laboratory research that has been performed to explore the mechanisms of Parkinson's disease (PD), its pathogenesis remains elusive to date. Therefore, this study aimed to identify possible regulators of neurodegeneration by performing microarray analysis of the zebrafish PD model's brain following rotenone exposure.

METHODS

A total of 36 adult zebrafish were divided into two groups: control (n = 17) and rotenonetreated (n = 19). Fish were treated with rotenone water (5 μg/L water) for 28 days and subjected to locomotor behavior analysis. Total RNA was extracted from the brain tissue after rotenone treatment. The cDNA synthesized was subjected to microarray analysis and subsequently validated by qPCR.

RESULTS

Administration of rotenone has significantly reduced locomotor activity in zebrafish (p < 0.05), dysregulated dopamine-related gene expression (dat, th1, and th2, p < 0.001), and reduced dopamine level in the brain (p < 0.001). In the rotenone-treated group, genes involved in cytotoxic T lymphocytes (gzm3, cd8a, p < 0.001) and T cell receptor signaling (themis, lck, p < 0.001) were upregulated significantly. Additionally, gene expression involved in microgliosis regulation (tyrobp, p < 0.001), cellular response to IL-1 (ccl34b4, il2rb, p < 0.05), and regulation of apoptotic process (dedd1, p < 0.001) were also upregulated significantly.

CONCLUSION

The mechanisms of T cell receptor signaling, microgliosis regulation, cellular response to IL-1, and apoptotic signaling pathways have potentially contributed to PD development in rotenonetreated zebrafish.

Exploring the Central Mechanisms of Botulinum Toxin in Parkinson's Disease: A Systematic Review from Animal Models to Human Evidence

Botulinum toxin (BoNT) is an effective and safe therapy for the symptomatic treatment of several neurological disturbances. An important line of research has provided numerous pieces of evidence about the mechanisms of action of BoNT in the central nervous system, especially in the context of dystonia and spasticity. However, only a few studies focused on the possible central effects of BoNT in Parkinson's disease (PD). We performed a systematic review to describe and discuss the evidence from studies focused on possible central effects of BoNT in PD animal models and PD patients. To this aim, a literature search in PubMed and SCOPUS was performed in May 2023. The records were screened according to title and abstract by two independent reviewers and relevant articles were selected for full-text review. Most of the papers highlighted by our review report that the intrastriatal administration of BoNT, through local anticholinergic action and the remodulation of striatal compensatory mechanisms secondary to dopaminergic denervation, induces an improvement in motor and non-motor symptoms in the absence of neuronal loss in animal models of PD. In human subjects, the data are scarce: a single neurophysiological study in tremulous PD patients found that the change in tremor severity after peripheral BoNT administration was associated with improved sensory-motor integration and intracortical inhibition measures. Further clinical, neurophysiological, and neuroimaging studies are necessary to clarify the possible central effects of BoNT in PD.

Mitochondrial Hydrogen Peroxide Activates PTEN and Inactivates Akt Leading to Autophagy Inhibition-Dependent Cell Death in Neuronal Models of Parkinson's Disease

Defective autophagy relates to the pathogenesis of Parkinson's disease (PD), a typical neurodegenerative disease. Our recent study has demonstrated that PD toxins (6-OHDA, MPP+, or rotenone) induce neuronal apoptosis by impeding the AMPK/Akt-mTOR signaling. Here, we show that treatment with 6-OHDA, MPP+, or rotenone triggered decreases of ATG5/LC3-II and autophagosome formation with a concomitant increase of p62 in PC12, SH-SY5Y cells, and primary neurons, suggesting inhibition of autophagy. Interestingly, overexpression of wild-type ATG5 attenuated the inhibitory effect of PD toxins on autophagy, reducing neuronal apoptosis. The effects of PD toxins on autophagy and apoptosis were found to be associated with activation of PTEN and inactivation of Akt. Overexpression of dominant negative PTEN, constitutively active Akt and/or pretreatment with rapamycin rescued the cells from PD toxins-induced downregulation of ATG5/LC3-II and upregulation of p62, as well as consequential autophagosome diminishment and apoptosis in the cells. The effects of PD toxins on autophagy and apoptosis linked to excessive intracellular and mitochondrial hydrogen peroxide (H2O2) production, as evidenced by using a H2O2-scavenging enzyme catalase, a mitochondrial superoxide indicator MitoSOX and a mitochondria-selective superoxide scavenger Mito-TEMPO. Furthermore, we observed that treatment with PD toxins reduced the protein level of Parkin in the cells. Knockdown of Parkin alleviated the effects of PD toxins on H2O2 production, PTEN/Akt activity, autophagy, and apoptosis in the cells, whereas overexpression of wild-type Parkin exacerbated these effects of PD toxins, implying the involvement of Parkin in the PD toxins-induced oxidative stress. Taken together, the results indicate that PD toxins can elicit mitochondrial H2O2, which can activate PTEN and inactivate Akt leading to autophagy inhibition-dependent neuronal apoptosis, and Parkin plays a critical role in this process. Our findings suggest that co-manipulation of the PTEN/Akt/autophagy signaling by antioxidants may be exploited for the prevention of neuronal loss in PD.

Impaired autophagy aggravates oxidative stress in mammary gland of dairy cows with clinical ketosis

When ketosis occurs, supraphysiological levels of free fatty acids (FFA) can cause oxidative injury to the mammary gland and autophagy can regulate the cellular oxidative status. The aim of this study was to investigate the autophagy status of mammary tissue and its associations with oxidative stress in healthy and clinically ketotic dairy cows. Mammary tissue and blood samples were collected from healthy cows [n = 15, β-hydroxybutyrate (BHB) <0.6 mM] and clinically ketotic cows (n = 15, BHB >3.0 mM) at 3 to 15 (average = 7) days in milk. For in vitro study, bovine mammary epithelial cells (BMEC) isolated from healthy cows were treated with 0, 0.3, 0.6, or 1.2 mM FFA for 24 h. Furthermore, BMEC were pretreated with 100 nM rapamycin, an autophagy activator, for 4 h or 50 mM 3-methyladenine (3-MA), an autophagy inhibitor, for 1 h, followed by treatment with or without FFA (1.2 mM) for another 24 h. Oxidation indicators and autophagy-related protein abundance were measured. Compared with healthy cows, serum concentrations of FFA, BHB, and malondialdehyde were greater in clinically ketotic cows, but milk production (kg/d), milk protein (kg/d), activities of superoxide dismutase, catalase, and glutathione peroxidase were lower. Abundances of mRNA and protein of autophagy-related gene 5 (ATG5) and 7 (ATG7) were lower, but sequestosome-1 (SQSTM1, also called p62) greater in mammary tissue of clinically ketotic cows. The mRNA abundance of microtubule-associated protein 1 light chain 3 (MAP1LC3, also called LC3) and protein abundance of LC3-II were lower in mammary tissue of clinically ketotic cows. In vitro, exogenous FFA increased the content of malondialdehyde and reactive oxygen species, but decreased the activities of superoxide dismutase, catalase, and plasma glutathione peroxidase. Compared with the 0 mM FFA group, abundance of ATG5, ATG7, LC3-II was greater, but p62 was lower in the 0.6 mM FFA-treated cells. Similarly, abundance of ATG5, ATG7, and LC3-II was lower, but p62 greater in the 1.2 mM FFA-treated cells relative to 0 mM FFA group. Culture with rapamycin alleviated oxidative stress induced by 1.2 mM FFA, whereas 3-MA aggravated it. Overall, results indicated that a low concentration (0.6 mM) of FFA can induce oxidative stress and activate autophagy in BMEC. At higher concentrations of FFA (1.2 mM), autophagy is impaired and oxidative stress is aggravated. Autophagy is a mechanism for BMEC to counteract FFA-induced stress. As such, it could serve as a potential target for further development of novel strategies against oxidative stress.

Triptolide promotes autophagy to inhibit mesangial cell proliferation in IgA nephropathy via the CARD9/p38 MAPK pathway

Background

Mesangial cell proliferation is the most basic pathological feature of immunoglobulin A nephropathy (IgAN); however, the specific underlying mechanism and an appropriate therapeutic strategy are yet to be unearthed. This study aimed to investigate the therapeutic effect of triptolide (TP) on IgAN and the mechanism by which TP regulates autophagy and proliferation of mesangial cells through the CARD9/p38 MAPK pathway.

Methods

We established a TP‐treated IgAN mouse model and produced IgA1‐induced human mesangial cells (HMC) and divided them into control, TP, IgAN, and IgAN+TP groups. The levels of mesangial cell proliferation (PCNA, cyclin D1, cell viability, and cell cycle) and autophagy (P62, LC3 II, and autophagy flux rate) were measured, with the autophagy inhibitor 3‐Methyladenine used to explore the relationship between autophagy and proliferation. We observed CARD9 expression in renal biopsies from patients and analyzed its clinical significance. CARD9 siRNA and overexpression plasmids were constructed to investigate the changes in mesangial cell proliferation and autophagy as well as the expression of CARD9 and p‐p38 MAPK/p38 MAPK following TP treatment.

Results

Administering TP was safe and effectively alleviated mesangial cell proliferation in IgAN mice. Moreover, TP inhibited IgA1‐induced HMC proliferation by promoting autophagy. The high expression of CARD9 in IgAN patients was positively correlated with the severity of HMC proliferation. CARD9/p38 MAPK was involved in the regulation of HMC autophagy and proliferation, and TP promoted autophagy to inhibit HMC proliferation by downregulating the CARD9/p38 MAPK pathway in IgAN.

Conclusion

TP promotes autophagy to inhibit mesangial cell proliferation in IgAN via the CARD9/p38 MAPK pathway.

Polydatin attenuates chronic alcohol consumption-induced cardiomyopathy through a SIRT6-dependent mechanism

Polydatin has attracted much attention as a potential cardioprotective agent against ischemic heart disease and diabetic cardiomyopathy. However, the effect and mechanism of polydatin supplementation on alcoholic cardiomyopathy (ACM) are still unknown. This study aimed to determine the therapeutic effect of polydatin against ACM and to explore the molecular mechanisms with a focus on SIRT6-AMP-activated protein kinase (AMPK) signaling and mitochondrial function. The ACM model was established by feeding C57/BL6 mice with an ethanol Lieber-DeCarli diet for 12 weeks. The mice received polydatin (20 mg kg^-1) or vehicle treatment. We showed that polydatin treatment not only improved cardiac function but also reduced myocardial fibrosis and dynamin-related protein 1 (Drp-1)-mediated mitochondrial fission, and enhanced PTEN-induced putative kinase 1 (PINK1)-Parkin-dependent mitophagy in alcohol-treated myocardium. Importantly, these beneficial effects were mimicked by SIRT6 overexpression but abolished by the infection of recombinant serotype 9 adeno-associated virus (AAV9) carrying SIRT6-specific small hairpin RNA. Mechanistically, alcohol consumption induced a gradual decrease in the myocardial SIRT6 level, while polydatin effectively activated SIRT6-AMPK signaling and modulated mitochondrial dynamics and mitophagy, thus reducing oxidative stress damage and preserving mitochondrial function. In summary, these data present new information regarding the therapeutic actions of polydatin, suggesting that the activation of SIRT6 signaling may represent a new approach for tackling ACM-related cardiac dysfunction.

Roflupram attenuates α-synuclein-induced cytotoxicity and promotes the mitochondrial translocation of Parkin in SH-SY5Y cells overexpressing A53T mutant α-synuclein

We have previously shown that inhibition of cAMP-specific 3',5'-cyclic phosphodiesterase 4 (PDE4) protects against cellular toxicity in neuronal cells. Since α-synuclein (α-syn) toxicity contributes to the neurodegeneration of Parkinson's disease (PD). The aim of this study was to explore the effects and mechanisms of PDE4 on α-syn-induced neuronal toxicity. Using mutant human A53T α-syn overexpressed SH-SY5Y cells, we found that PDE4B knockdown reduced cellular apoptosis. Roflupram (ROF, 20 μM), a selective PDE4 inhibitor, produced similar protective effects and restored the morphological alterations of mitochondria. Mechanistic studies identified that α-syn enhanced the phosphorylation of Parkin at Ser131, followed by the decreased mitochondrial translocation of Parkin. Whereas both PDE4B knockdown and PDE4 inhibition by ROF blocked the effects of α-syn on Parkin phosphorylation and mitochondrial translocation. Moreover, PDE4 inhibition reversed the increase in the phosphorylation of p38 mitogen-activated protein kinase (MAPK) induced by α-syn. ROF treatment also reduced the binding of p38 MAPK to Parkin. Consistently, overexpression of PDE4B blocked the roles of ROF on p38 MAPK phosphorylation, Parkin phosphorylation, and the subsequent mitochondrial translocation of parkin. Furthermore, PDE4B overexpression attenuated the protective role of ROF, as evidenced by reduced mitochondria membrane potential and increased cellular apoptosis. Interestingly, ROF failed to suppress α-syn-induced cytotoxicity in the presence of a protein kinase A (PKA) inhibitor H-89. Our findings indicate that PDE4 facilitates α-syn-induced cytotoxicity via the PKA/p38 MAPK/Parkin pathway in SH-SY5Y cells overexpressing A53T mutant α-synuclein. PDE4 inhibition by ROF is a promising strategy for the prevention and treatment of α-syn-induced neurodegeneration.

Botulinum Toxin A Ameliorates Neuroinflammation in the MPTP and 6-OHDA-Induced Parkinson's Disease Models

Recently, increasing evidence suggests that neuroinflammation may be a critical factor in the development of Parkinson's disease (PD) in addition to the ratio of acetylcholine/dopamine because dopaminergic neurons are particularly vulnerable to inflammatory attack. In this study, we investigated whether botulinum neurotoxin A (BoNT-A) was effective for the treatment of PD through its anti-neuroinflammatory effects and the modulation of acetylcholine and dopamine release. We found that BoNT-A ameliorated MPTP and 6-OHDA-induced PD progression, reduced acetylcholine release, levels of IL-1β, IL-6 and TNF-α as well as GFAP expression, but enhanced dopamine release and tyrosine hydroxylase expression. These results indicated that BoNT-A had beneficial effects on MPTP or 6-OHDA-induced PD-like behavior impairments via its anti-neuroinflammation properties, recovering dopamine, and reducing acetylcholine release.

Rotenone-Induced Neurodegeneration Is Enabled by a p38-Parkin-ROS Signaling Feedback Loop

Rotenone, a component of pesticides, is widely used in agriculture and potentially causes Parkinson's disease (PD). However, the regulatory mechanisms of rotenone-induced PD are unclear. Here, we revealed a novel feedback mechanism of p38-Parkin-ROS regulating rotenone-induced PD. Rotenone treatment led to not only the activation of p38 but also Parkin inactivation and reactive oxygen species (ROS) overproduction in SN4741 cells. Meanwhile, p38 activation regulated Parkin phosphorylation at serine 131 to disrupt Parkin-mediated mitophagy. Notably, both p38 inhibition and Parkin overexpression decreased ROS levels. Additionally, the ROS inhibitor N-acetyl-l-cysteine (NAC) inhibited p38 and activated Parkin-mediated mitophagy. Both p38 inhibition and the ROS inhibitor NAC exerted a protective effect by restoring cell death and mitochondrial function in rotenone-induced PD models. Based on these results, the p38-Parkin-ROS signaling pathway is involved in neurodegeneration. This pathway represents a valuable treatment strategy for rotenone-induced PD, and our study provides basic research evidence for the safe use of rotenone in agriculture.

Free fatty acids impair autophagic activity and activate nuclear factor kappa B signaling and NLR family pyrin domain containing 3 inflammasome in calf hepatocytes

Free fatty acids (FFA)-induced hepatic inflammation agravates liver injury and metabolic dysfunction in dairy cows with ketosis or fatty liver. Under stressful conditions, autophagy is generally considered as a cell protection mechanism, but whether the FFA-induced inflammatory and stress effect on hepatocytes involves an autophagy response is not well known. Thus, the objective of this study was to investigate the effects of FFA on autophagy and the role of autophagy in the activation of NF-κB (nuclear factor kappa B) signaling and NLRP3 (NLR family pyrin domain containing 3) inflammasome in calf hepatocytes. Calf hepatocytes were isolated from 3 healthy Holstein female new-born calves (1 d of age, 30-40 kg) and exposed to various concentrations of FFA (0, 0.3, 0.6, or 1.2 mM) after treatment with or without the autophagy inhibitor chloroquine (CQ) or the autophagy activator rapamycin. Expression of autophagy markers, LC3 (microtubule-associated protein 1 light chain 3) and p62 (sequestosome 1), NF-κB signaling, and NLRP3 inflammasome-related molecules were analyzed via western blot and quantitative real-time PCR. Results revealed that 0.6 and 1.2 mM FFA activated NF-κB signaling and NLRP3 inflammasome as indicated by an elevated ratio of p-NF-κB/NF-κB, protein abundance of NLRP3 and CASP1 (caspase 1), activity of CASP1, and mRNA abundance of IL1B and IL18. In addition, hepatocyte treated with 0.6 and 1.2 mM FFA or autophagy inhibitor CQ displayed increased protein abundance of p62 and LC3-II. Moreover, there was no difference in protein abundance of p62 and LC3-II between calf hepatocytes treated with 1.2 mM FFA and 1.2 mM FFA plus CQ, indicating that FFA inhibits autophagic activity in calf hepatocytes. Treatment with CQ led to overactivation of NF-κB signaling and NLRP3 inflammasome. Furthermore, CQ plus 1.2 mM FFA aggravated FFA-induced inflammation. In contrast, induction of autophagy by rapamycin ameliorated the FFA-activated NF-κB signaling and NLRP3 inflammasome as demonstrated by a lower ratio of p-NF-κB/NF-κB, protein abundance of NLRP3 and CASP1, activity of CASP1, and mRNA abundance of IL1B and IL18. Overall, inhibition of autophagy exacerbated, whereas induction of autophagy alleviated, FFA-induced inflammatory processes in calf hepatocytes, suggesting that impairment of autophagy might be partly responsible for hepatic inflammation and subsequent liver injury in dairy cows with ketosis or fatty liver. As such, regulation of autophagy may be an effective therapeutic strategy for controlling overt inflammatory responses in vivo.

Exploring the Role of Autophagy Dysfunction in Neurodegenerative Disorders

Autophagy is a catabolic pathway by which misfolded proteins or damaged organelles are engulfed by autophagosomes and then transported to lysosomes for degradation. Recently, a great improvement has been done to explain the molecular mechanisms and roles of autophagy in several important cellular metabolic processes. Besides being a vital clearance pathway or a cell survival pathway in response to different stresses, autophagy dysfunction, either upregulated or down-regulated, has been suggested to be linked with numerous neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, Huntington's disease, and Amyotrophic lateral sclerosis. Impairment at different stages of autophagy results in the formation of large protein aggregates and damaged organelles, which leads to the onset and progression of different neurodegenerative disorders. This article elucidates the recent progress about the role of autophagy in neurodegenerative disorders and explains how autophagy dysfunction is linked with the pathogenesis of such disorders as well as the novel potential autophagy-associated therapies for treating them.

Propionate alleviates palmitic acid-induced endoplasmic reticulum stress by enhancing autophagy in calf hepatic cells

Negative energy balance-induced high blood concentrations of free fatty acids during the early postpartum period in dairy cows is a major cause of liver injury. Cows in severe negative energy balance often have suboptimal intakes of feed, which contributes to shortfalls in production of ruminal propionate and circulating glucose. Although increasing propionate production by the rumen through feed additives such as propylene glycol is effective in helping cows alleviate the shortfall in dietary energy supply, mechanisms whereby propionate affects liver function beyond gluconeogenesis are unknown. Therefore, the objective of this study was to investigate whether propionate could protect calf hepatic cells from palmitic acid (PA)-induced lipotoxicity and the underlying mechanisms. Calf hepatic cells were isolated from 5 healthy calves (1 d old, female, 30-40 kg, fasting) and treated with various concentrations of PA (0, 100, 200, or 400 μM) and propionate (0, 1, 2, or 4 mM) after being administered with or without autophagic inhibitor. Propionate enhanced autophagic activity in calf hepatic cells, as indicated by elevated expression of autophagy markers LC3-II (microtubule-associated protein 1 light chain 3-II, encoded by MAP1LC3) and decreased expression of SQSTM1 (sequestosome-1, also called p62). Conversely, PA suppressed autophagic activity and decreased cell viability, which was improved by propionate in calf hepatic cells. In addition, propionate decreased the phosphorylation of proteins EIF2AK3 (kinase R/PKR like ER kinase) and ERN1 (inositol-requiring enzyme 1α) and cleaved ATF6 (activating transcription factor 6) in PA-treated calf hepatic cells, indicating the suppression effect of propionate on endoplasmic reticulum (ER) stress. However, inhibition of autophagic activity by chloroquine or bafilomycin A1 impede the beneficial effects of propionate on ER stress and cell viability. These results demonstrated that propionate alleviates ER stress and elevates cell viability in PA-treated calf hepatic cells by enhancing autophagy, which implies that autophagy may be a promising target in improving liver injury of dairy cows during transition period.

Genes Implicated in Familial Parkinson's Disease Provide a Dual Picture of Nigral Dopaminergic Neurodegeneration with Mitochondria Taking Center Stage

The mechanism of nigral dopaminergic neuronal degeneration in Parkinson's disease (PD) is unknown. One of the pathological characteristics of the disease is the deposition of α-synuclein (α-syn) that occurs in the brain from both familial and sporadic PD patients. This paper constitutes a narrative review that takes advantage of information related to genes (SNCA, LRRK2, GBA, UCHL1, VPS35, PRKN, PINK1, ATP13A2, PLA2G6, DNAJC6, SYNJ1, DJ-1/PARK7 and FBXO7) involved in familial cases of Parkinson's disease (PD) to explore their usefulness in deciphering the origin of dopaminergic denervation in many types of PD. Direct or functional interactions between genes or gene products are evaluated using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. The rationale is to propose a map of the interactions between SNCA, the gene encoding for α-syn that aggregates in PD, and other genes, the mutations of which lead to early-onset PD. The map contrasts with the findings obtained using animal models that are the knockout of one of those genes or that express the mutated human gene. From combining in silico data from STRING-based assays with in vitro and in vivo data in transgenic animals, two likely mechanisms appeared: (i) the processing of native α-syn is altered due to the mutation of genes involved in vesicular trafficking and protein processing, or (ii) α-syn mutants alter the mechanisms necessary for the correct vesicular trafficking and protein processing. Mitochondria are a common denominator since both mechanisms require extra energy production, and the energy for the survival of neurons is obtained mainly from the complete oxidation of glucose. Dopamine itself can result in an additional burden to the mitochondria of dopaminergic neurons because its handling produces free radicals. Drugs acting on G protein-coupled receptors (GPCRs) in the mitochondria of neurons may hopefully end up targeting those receptors to reduce oxidative burden and increase mitochondrial performance. In summary, the analysis of the data of genes related to familial PD provides relevant information on the etiology of sporadic cases and might suggest new therapeutic approaches.

Intracellular signaling molecules of nerve tissue progenitors as pharmacological targets for treatment of ethanol-induced neurodegeneration

OBJECTIVES

The development of approaches to the treatment of neurodegenerative diseases caused by alcohol abuse by targeted pharmacological regulation of intracellular signaling transduction of progenitor cells of nerve tissue is promising. We studied peculiarities of participation of NF-кB-, сАМР/РКА-, JAKs/STAT3-, ERK1/2-, p38-pathways in the regulation of neural stem cells (NSC) and neuronal-committed progenitors (NCP) in the simulation of ethanol-induced neurodegeneration in vitro and in vivo.

METHODS

In vitro, the role of signaling molecules (NF-кB, сАМР, РКА, JAKs, STAT3, ERK1/2, p38) in realizing the growth potential of neural stem cells (NSC) and neuronal-committed progenitors (NCP) in ethanol-induced neurodegeneration modeled in vitro and in vivo was studied. To do this, the method of the pharmacological blockade with the use of selective inhibitors of individual signaling molecules was used.

RESULTS

Several of fundamental differences in the role of certain intracellular signaling molecules (SM) in proliferation and specialization of NSC and NCP have been revealed. It has been shown that the effect of ethanol on progenitors is accompanied by the formation of a qualitatively new pattern of signaling pathways. Data have been obtained on the possibility of stimulation of nerve tissue regeneration in ethanol-induced neurodegeneration by NF-кB and STAT3 inhibitors. It has been found that the blockage of these SM stimulates NSC and NCP in conditions of ethanol intoxication and does not have a «negative» effect on the realization of the growth potential of intact progenitors (which will appear de novo during therapy).

CONCLUSIONS

The results may serve as a basis for the development of fundamentally new drugs to the treatment of alcoholic encephalopathy and other diseases of the central nervous system associated with alcohol abuse.

Melatonin and Autophagy in Aging-Related Neurodegenerative Diseases

With aging, the nervous system gradually undergoes degeneration. Increased oxidative stress, endoplasmic reticulum stress, mitochondrial dysfunction, and cell death are considered to be common pathophysiological mechanisms of various neurodegenerative diseases (NDDs) such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), organophosphate-induced delayed neuropathy (OPIDN), and amyotrophic lateral sclerosis (ALS). Autophagy is a cellular basic metabolic process that degrades the aggregated or misfolded proteins and abnormal organelles in cells. The abnormal regulation of neuronal autophagy is accompanied by the accumulation and deposition of irregular proteins, leading to changes in neuron homeostasis and neurodegeneration. Autophagy exhibits both a protective mechanism and a damage pathway related to programmed cell death. Because of its "double-edged sword", autophagy plays an important role in neurological damage and NDDs including AD, PD, HD, OPIDN, and ALS. Melatonin is a neuroendocrine hormone mainly synthesized in the pineal gland and exhibits a wide range of biological functions, such as sleep control, regulating circadian rhythm, immune enhancement, metabolism regulation, antioxidant, anti-aging, and anti-tumor effects. It can prevent cell death, reduce inflammation, block calcium channels, etc. In this review, we briefly discuss the neuroprotective role of melatonin against various NDDs via regulating autophagy, which could be a new field for future translational research and clinical studies to discover preventive or therapeutic agents for many NDDs.

Dietary Antioxidants and Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder caused by the depletion of dopaminergic neurons in the basal ganglia, the movement center of the brain. Approximately 60,000 people are diagnosed with PD in the United States each year. Although the direct cause of PD can vary, accumulation of oxidative stress-induced neuronal damage due to increased production of reactive oxygen species (ROS) or impaired intracellular antioxidant defenses invariably occurs at the cellular levels. Pharmaceuticals such as dopaminergic prodrugs and agonists can alleviate some of the symptoms of PD. Currently, however, there is no treatment to halt the progression of PD pathology. Due to the nature of PD, a long and progressive neurodegenerative process, strategies to prevent or delay PD pathology may be well suited to lifestyle changes like dietary modification with antioxidant-rich foods to improve intracellular redox homeostasis. In this review, we discuss cellular and genetic factors that increase oxidative stress in PD. We also discuss neuroprotective roles of dietary antioxidants including vitamin C, vitamin E, carotenoids, selenium, and polyphenols along with their potential mechanisms to alleviate PD pathology.

Parkin deficiency accentuates chronic alcohol intake-induced tissue injury and autophagy defects in brain, liver and skeletal muscle

Alcoholism leads to organ injury including mitochondrial defect and apoptosis with evidence favoring a role for autophagy dysregulation in alcoholic damage. Parkin represents an autosomal recessive inherited gene for Parkinson's disease and an important member of selective autophagy for mitochondria. The association between Parkinson's disease and alcoholic injury remains elusive. This study aimed to examine the effect of parkin deficiency on chronic alcohol intake-induced organ injury in brain, liver and skeletal muscle (rectus femoris muscle). Adult parkin-knockout (PRK-/-) and wild-type mice were placed on Liber-De Carli alcohol liquid diet (4%) for 12 weeks prior to assessment of liver enzymes, intraperitoneal glucose tolerance, protein carbonyl content, apoptosis, hematoxylin and eosin morphological staining, and mitochondrial respiration (cytochrome c oxidase, NADH:cytochrome c reductase and succinate:cytochrome c reductase). Autophagy protein markers were monitored by western blot analysis. Our data revealed that chronic alcohol intake imposed liver injury as evidenced by elevated aspartate aminotransferase and alanine transaminase, glucose intolerance, elevated protein carbonyl formation, apoptosis, focal inflammation, necrosis, microvesiculation, autophagy/mitophagy failure and dampened mitochondrial respiration (complex IV, complexes I and III, and complexes II and III) in the brain, liver and rectus femoris skeletal muscle. Although parkin ablation itself did not generate any notable effects on liver enzymes, insulin sensitivity, tissue carbonyl damage, apoptosis, tissue morphology, autophagy or mitochondrial respiration, it accentuated alcohol intake-induced tissue damage, apoptosis, morphological change, autophagy/mitophagy failure and mitochondrial injury without affecting insulin sensitivity. These data suggest that parkin plays an integral role in the preservation against alcohol-induced organ injury, apoptosis and mitochondrial damage.

Polyphenols from Toona sinensiss Seeds Alleviate Neuroinflammation Induced by 6-Hydroxydopamine Through Suppressing p38 MAPK Signaling Pathway in a Rat Model of Parkinson's Disease

Polyphenols from Toona sinensis seeds (PTSS) have demonstrated anti-inflammatory effects in various diseases, while the anti-neuroinflammatory effects still remain to be investigated. We aimed to investigate the effects of PTSS on Parkinson's disease and underlying mechanisms using a rat model. We employed 6-hydroxydopamine (6-OHDA) to male Sprague Dawley (SD) rats and PC12 cells to construct the in vivo and vitro models of PD and dopaminergic (DA) neuron injury, respectively. Cell viability was detected by cell counting kit-8 (CCK-8) assay and protein levels of inflammatory mediators and some p38 MAPK pathway molecules were investigated by immunohistochemistry and Western blot analyses. The results showed that 6-OHDA significantly increased protein levels of inflammatory mediators, such as cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and tumor necrosis factor α (TNF-α), which could be reversed by PTSS through suppressing the p38 MAPK pathway. The anti-inflammatory effects of PTSS were significantly enhanced by the specific p38 inhibitor of SB203580 in vitro. The present work suggests that PTSS can exert anti-inflammatory effects on PD models, which may be attributed to the suppression of p38 MAPK signaling pathway.

α-Synuclein Regulates Iron Homeostasis via Preventing Parkin-Mediated DMT1 Ubiquitylation in Parkinson's Disease Models

Iron metabolism imbalance plays a key role in the neurodegeneration of Parkinson's disease (PD), thus iron homeostasis should be tightly controlled by iron transporters. α-Synuclein (α-Syn) serves as a ferrireductase and iron-binding protein, which is supposed to be linked with iron metabolism, but little is known about how α-Syn affects iron homeostasis in PD. Our previous findings that up-regulation of divalent metal transporter 1 (DMT1) accounted for the nigral iron accumulation in PD raised the question whether α-Syn disturbed iron homeostasis by modulating DMT1 expression. Using α-Syn overexpressed SH-SY5Y cells and mutant human A53T α-Syn transgenic mice, we found that α-Syn could up-regulate DMT1 protein levels, followed by enhanced ferrous iron influx and subsequent aggravated oxidative stress injury. Mechanistic studies identified that α-Syn-induced p38 mitogen-activated protein kinase (MAPK) activation phosphorylated parkin at Ser131, which inactivated parkin's E3 ubiquitin ligase activity and further reduced DMT1 ubiquitylation level. Our findings revealed that α-Syn affected brain iron homeostasis through modulating DMT1 protein stability and altering cellular iron uptake, which might provide direct evidence for the involvement of α-Syn in iron metabolism dysfunction and provide insight into PD-associated nigral iron deposition.

Neuroprotective Effects of Grape Seed Procyanidins on Ethanol-Induced Injury and Oxidative Stress in Rat Hippocampal Neurons

Aims

Ethanol is a small molecule capable of interacting with numerous targets in the brain, the mechanisms of which are complex and still poorly understood. Studies have revealed that ethanol-induced hippocampal neuronal injury is associated with oxidative stress. Grape seed procyanidin (GSP) is a new type of antioxidant that is believed to scavenge free radicals and be anti-inflammatory. This study evaluated the ability and mechanism by which the GSP improves ethanol-induced hippocampal neuronal injury.

Methods

Primary cultures of hippocampal neurons were exposed to ethanol (11, 33 and 66 mM, 1, 4, 8, 12 and 24 h) and the neuroprotective effects of GSP were assessed by evaluating the activity of superoxide dismutase (SOD), the levels of malondialdehyde (MDA) and lactate dehydrogenase (LDH) and cell morphology.

Results

Our results indicated that GSP prevented ethanol-induced neuronal injury by reducing the levels of MDA and LDH, while increasing the activity of SOD. In addition, GSP increased the number of primary dendrites and total dendritic length per cell.

Conclusion

Together with previous findings, these results lend further support to the significance of developing GSP as a therapeutic tool for use in the treatment of alcohol use disorders.

(E)-2-methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) Phenol Ameliorates MPTP-Induced Dopaminergic Neurodegeneration by Inhibiting the STAT3 Pathway

Neuroinflammation is implicated in dopaminergic neurodegeneration. We have previously demonstrated that (E)-2-methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol (MMPP), a selective signal transducer and activator of transcription 3 (STAT3) inhibitor, has anti-inflammatory properties in several inflammatory disease models. We investigated whether MMPP could protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic cell loss and behavioral impairment. Imprinting control region (ICR) mice (8 weeks old, n = 10 per group) were administered MMPP (5 mg/kg) in drinking water for 1 month, and injected with MPTP (15 mg/kg, four times with 2 h intervals) during the last 7 days of treatment. MMPP decreased MPTP-induced behavioral impairments in rotarod, pole, and gait tests. We also showed that MMPP ameliorated dopamine depletion in the striatum and inflammatory marker elevation in primary cultured neurons by high-performance liquid chromatography and immunohistochemical analysis. Increased activation of STAT3, p38, and monoamine oxidase B (MAO-B) were observed in the substantia nigra and striatum after MPTP injection, effects that were attenuated by MMPP treatment. Furthermore, MMPP inhibited STAT3 activity and expression of neuroinflammatory proteins, including ionized calcium binding adaptor molecule 1 (Iba1), inducible nitric oxide synthase (iNOS), and glial fibrillary acidic protein (GFAP) in 1-methyl-4-phenylpyridinium (MPP⁺; 0.5 mM)-treated primary cultured cells. However, mitogen-activated protein kinase (MAPK) inhibitors augmented the activity of MMPP. Collectively, our results suggest that MMPP may be an anti-inflammatory agent that attenuates dopaminergic neurodegeneration and neuroinflammation through MAO-B and MAPK pathway-dependent inhibition of STAT3 activation.

Recent progress in the role of autophagy in neurological diseases

Autophagy (here refers to macroautophagy) is a catabolic pathway by which large protein aggregates and damaged organelles are first sequestered into a double-membraned structure called autophago-some and then delivered to lysosome for destruction. Recently, tremen-dous progress has been made to elucidate the molecular mechanism and functions of this essential cellular metabolic process. In addition to being either a rubbish clearing system or a cellular surviving program in response to different stresses, autophagy plays important roles in a large number of pathophysiological conditions, such as cancer, diabetes, and especially neurodegenerative disorders. Here we review recent progress in the role of autophagy in neurological diseases and discuss how dysregulation of autophagy initiation, autophagosome formation, maturation, and/or au-tophagosome-lysosomal fusion step contributes to the pathogenesis of these disorders in the nervous system.

Ethanol-Induced Mitochondrial Damage in Sertoli Cells is Associated with Parkin Overexpression and Activation of Mitophagy

This study was conducted to elucidate the involvement of the PINK1-Parkin pathway in ethanol-induced mitophagy among Sertoli cells (SCs). In the research, adult rats were given intraperitoneal injections of ethanol (5 gm/kg) and sacrificed at various time periods within 24 h. Transmission electron microscopy was applied to reveal enhanced mitochondrial damage in SCs of the ethanol-treated rats (ETRs) in association with a significant increase in numbers of mitophagic vacuoles (mitophagosomes and autolysosomes) in contrast to very low levels in a control group treated with phosphate-buffered saline (PBS). This enhancement was ultra-structurally verified via observation of trapped mitochondria within LC3-labeled membranes, upregulation of LC3 protein levels, colocalization of LC3 and cytochrome c, and reduced expression of mitochondrial proteins. Importantly, Parkin expression was found to be upregulated in ETR SCs, specifically in mitochondria and mitophagosomes in addition to colocalization with PINK1 and pan-cathepsin, indicating augmented mitophagy. Transcription factor EB (TFEB, a transcription factor for autophagy and mitophagy proteins) was also found to be upregulated in nuclei of ETR SCs and associated with enhanced expression of iNOS. Enhanced Parkin-related mitophagy in ETR SCs may be a protective mechanism with therapeutic implications. To the authors' knowledge, this is the first report demonstrating the ultrastructural characteristics and molecular mechanisms of Parkin-related mitophagy in ETR SCs.

Impaired hepatic autophagic activity in dairy cows with severe fatty liver is associated with inflammation and reduced liver function

The ability of liver to respond to changes in nutrient availability is essential for the maintenance of metabolic homeostasis. Autophagy encompasses mechanisms of cell survival, including capturing, degrading, and recycling of intracellular proteins and organelles in lysosomes. During negative nutrient status, autophagy provides substrates to sustain cellular metabolism and hence, tissue function. Severe negative energy balance in dairy cows is associated with fatty liver. The aim of this study was to investigate the hepatic autophagy status in dairy cows with severe fatty liver and to determine associations with biomarkers of liver function and inflammation. Liver and blood samples were collected from multiparous cows diagnosed as clinically healthy (n = 15) or with severe fatty liver (n = 15) at 3 to 9 d in milk. Liver tissue was biopsied by needle puncture, and serum samples were collected on 3 consecutive days via jugular venipuncture. Concentrations of free fatty acids and β-hydroxybutyrate were greater in cows with severe fatty liver. Milk production, dry matter intake, and concentration of glucose were all lower in cows with severe fatty liver. Activities of serum aspartate aminotransferase, alanine aminotransferase, glutamate dehydrogenase, and γ-glutamyl transferase were all greater in cows with severe fatty liver. Serum concentrations of haptoglobin and serum amyloid A were also markedly greater in cows with severe fatty liver. The mRNA expression of autophagosome formation-related gene ULK1 was lower in the liver of dairy cows with severe fatty liver. However, the expression of other autophagosome formation-related genes, beclin 1 (BECN1), phosphatidylinositol 3-kinase catalytic subunit type 3 (PIK3C3), autophagy-related gene (ATG) 3, ATG5, and ATG12, did not differ. More important, ubiquitinated proteins, protein expression of sequestosome-1 (SQSTM1, also called p62), and microtubule-associated protein 1 light chain 3 (MAP1LC3, also called LC3)-II was greater in cows with severe fatty liver. Transmission electron microscopy revealed an increased number of autophagosomes in the liver of dairy cows with severe fatty liver. Taken together, these results indicate that excessive lipid infiltration of the liver impairs autophagic activity that may lead to cellular damage and inflammation.

Role of Mitogen Activated Protein Kinase Signaling in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder caused by insufficient dopamine production due to the loss of 50% to 70% of dopaminergic neurons. A shortage of dopamine, which is predominantly produced by the dopaminergic neurons within the substantia nigra, causes clinical symptoms such as reduction of muscle mass, impaired body balance, akinesia, bradykinesia, tremors, postural instability, etc. Lastly, this can lead to a total loss of physical movement and death. Since no cure for PD has been developed up to now, researchers using cell cultures and animal models focus their work on searching for potential therapeutic targets in order to develop effective treatments. In recent years, genetic studies have prominently advocated for the role of improper protein phosphorylation caused by a dysfunction in kinases and/or phosphatases as an important player in progression and pathogenesis of PD. Thus, in this review, we focus on the role of selected MAP kinases such as JNKs, ERK1/2, and p38 MAP kinases in PD pathology.

Phosphorylation of Parkin at serine 131 by p38 MAPK promotes mitochondrial dysfunction and neuronal death in mutant A53T α-synuclein model of Parkinson's disease

α-synuclein abnormal accumulation and mitochondria dysfunction are involved in the pathogenesis of Parkinson’s disease. Selective autophagy of mitochondria (mitophagy) is a crucial component of the network controlling the mitochondrial homeostasis. However, the underlying mechanism that mutant α-synuclein induces mitochondrial abnormality through mitophagy impairment is not fully understood. Here, we showed that mutant A53T α-synuclein accumulation impaired mitochondrial function and Parkin-mediated mitophgy in α-synucleinA53T model. α-synucleinA53T overexpression caused p38 MAPK activation, then p38 MAPK directly phosphorylated Parkin at serine 131 to disrupt the Parkin’s protective function. The p38 MAPK inhibition significantly reduced cellular apoptosis, restored mitochondrial membrane potential as well as increased synaptic density both in SN4741 cells and primary midbrain neurons. These findings show that the p38 MAPK-Parkin signaling pathway regulates mitochondrial homeostasis and neuronal degeneration, which may be a potential therapeutic strategy of PD via enhancing mitochondrial turn-over and maintenance.

Activation of Ca2+-sensing receptor as a protective pathway to reduce Cadmium-induced cytotoxicity in renal proximal tubular cells

Cadmium (Cd), as an extremely toxic metal could accumulate in kidney and induce renal injury. Previous studies have proved that Cd impact on renal cell proliferation, autophagy and apoptosis, but the detoxification drugs and the functional mechanism are still in study. In this study, we used mouse renal tubular epithelial cells (mRTECs) to clarify Cd-induced toxicity and signaling pathways. Moreover, we proposed to elucidate the prevent effect of activation of Ca²⁺ sensing receptor (CaSR) by Calcimimetic (R-467) on Cd-induced cytotoxicity and underlying mechanisms. Cd induced intracellular Ca²⁺ elevation through phospholipase C-inositol 1, 4, 5-trisphosphate (PLC) followed stimulating p38 mitogen-activated protein kinases (MAPK) activation and suppressing extracellular signal-regulated kinase (ERK) activation, which leaded to increase apoptotic cell death and inhibit cell proliferation. Cd induced p38 activation also contribute to autophagic flux inhibition that aggravated Cd induced apoptosis. R-467 reinstated Cd-induced elevation of intracellular Ca²⁺ and apoptosis, and it also increased cell proliferation and restored autophagic flux by switching p38 to ERK pathway. The identification of the activation of CaSR-mediated protective pathway in renal cells sheds light on a possible cellular protective mechanism against Cd-induced kidney injury.

Activation of AMPK/mTORC1-Mediated Autophagy by Metformin Reverses Clk1 Deficiency-Sensitized Dopaminergic Neuronal Death

The autophagy-lysosome pathway (ALP) plays a critical role in the pathology of Parkinson's disease (PD). Clk1 (coq7) is a mitochondrial hydroxylase that is essential for coenzyme Q (ubiquinone) biosynthesis. We have reported previously that Clk1 regulates microglia activation via modulating microglia metabolic reprogramming, which contributes to dopaminergic neuronal survival. This study explores the direct effect of Clk1 on dopaminergic neuronal survival. We demonstrate that Clk1 deficiency inhibited dopaminergic neuronal autophagy in cultured MN9D dopaminergic neurons and in the substantia nigra pars compacta of Clk+/- mutant mice and consequently sensitized dopaminergic neuron damage and behavioral defects. These mechanistic studies indicate that Clk1 regulates the AMP-activated protein kinase (AMPK)/rapamycin complex 1 pathway, which in turn impairs the ALP and TFEB nuclear translocation. As a result, Clk1 deficiency promotes dopaminergic neuronal damage in vivo and in vitro, which ultimately contributes to sensitizing 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neuronal death and behavioral impairments in Clk1-deficient mice. Moreover, we found that activation of autophagy by the AMPK activator metformin increases dopaminergic neuronal survival in vitro and in the MPTP-induced PD model in Clk1 mutant mice. These results reveal that Clk1 plays a direct role in dopaminergic neuronal survival via regulating ALPs that may contribute to the pathologic development of PD. Modulation of Clk1 activity may represent a potential therapeutic target for PD.